U.S. patent application number 14/203409 was filed with the patent office on 2014-11-06 for methods and apparatus for forming multi-layer structures using adhered masks.
The applicant listed for this patent is Microfabrica Inc.. Invention is credited to Adam L. Cohen, Uri Frodis, Marvin M. Kilgo, III, Michael S. Lockard, Dennis R. Smalley, Jill R. Thomassian.
Application Number | 20140326607 14/203409 |
Document ID | / |
Family ID | 33457101 |
Filed Date | 2014-11-06 |
United States Patent
Application |
20140326607 |
Kind Code |
A1 |
Cohen; Adam L. ; et
al. |
November 6, 2014 |
Methods and Apparatus for Forming Multi-Layer Structures Using
Adhered Masks
Abstract
Numerous electrochemical fabrication methods and apparatus are
provided for producing multi-layer structures (e.g. having
meso-scale or micro-scale features) from a plurality of layers of
deposited materials using adhered masks (e.g. formed from liquid
photoresist or dry film), where two or more materials may be
provided per layer where at least one of the materials is a
structural material and one or more of any other materials may be a
sacrificial material which will be removed after formation of the
structure. Materials may comprise conductive materials that are
electrodeposited or deposited in an electroless manner. In some
embodiments special care is undertaken to ensure alignment between
patterns formed on successive layers.
Inventors: |
Cohen; Adam L.; (Dallas,
TX) ; Thomassian; Jill R.; (Los Angeles, CA) ;
Lockard; Michael S.; (Lake Elizabeth, CA) ; Kilgo,
III; Marvin M.; (Oakland, CA) ; Frodis; Uri;
(Los Angeles, CA) ; Smalley; Dennis R.; (Newhall,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Microfabrica Inc. |
Van Nuys |
CA |
US |
|
|
Family ID: |
33457101 |
Appl. No.: |
14/203409 |
Filed: |
March 10, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13206133 |
Aug 9, 2011 |
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14203409 |
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12479638 |
Jun 5, 2009 |
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13206133 |
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10841272 |
May 7, 2004 |
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12479638 |
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60468741 |
May 7, 2003 |
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60474625 |
May 29, 2003 |
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Current U.S.
Class: |
205/128 ;
205/136 |
Current CPC
Class: |
C25D 1/20 20130101; C25D
5/02 20130101; C25D 5/022 20130101; C25D 5/10 20130101; C25D 1/003
20130101; C25D 5/50 20130101; C25D 5/14 20130101; C25D 1/00
20130101; C25D 5/48 20130101 |
Class at
Publication: |
205/128 ;
205/136 |
International
Class: |
C25D 5/02 20060101
C25D005/02 |
Claims
1. A method for forming a three-dimensional structure, comprising:
(A) forming a plurality of successively formed layers, wherein each
successive layer comprises at least two materials and is formed on
and adhered to a previously formed layer, one of the at least two
materials is a structural material and the other of the at least
two materials is a sacrificial material, and wherein each
successive layer defines a successive cross-section of the
three-dimensional structure, and wherein the forming of each of the
plurality of successive layers comprises: (i) depositing a first of
the at least two materials; (ii) depositing a second of the at
least two materials; (iii) planarizing the first and second
materials to set a boundary level for the layer; and wherein the
forming of a given one of the plurality of successively formed
layers comprises: (i) applying a 1st patternable mold material
(PMM) on the layer; (ii) patterning the 1st PMM to form a 1st
pattern; (iii) depositing a 1st material in the 1st pattern; (iv)
removing the 1st PMM to expose areas of the layer not having the
1st material deposited thereon; (v) depositing a 2nd PMM over the
layer; (vi) patterning the 2nd PMM to form a 2nd pattern, the 2nd
pattern including an aperture adjacent to the 1st material and
exposing a top portion of the 1st material; (vii) depositing a 2nd
material in the 2nd pattern formed and over the exposed top portion
of the 1st material; (viii) removing the 2nd PMM to expose areas of
the layer not having the 1st or 2nd materials deposited thereon;
(ix) depositing a third material over the 1st and 2nd materials and
over the exposed areas of the layer; and (x) planarizing the
deposited first--third materials to set a boundary level for the
given layer. (B) after the forming of the plurality of successive
layers, separating at least a portion of the sacrificial material
from multiple layers of the structural material to reveal the
three-dimensional structure.
2. The method of claim 1 wherein the PMM is a photoresist.
3. The method of claim 1 wherein the forming the three-dimensional
structure comprises the forming of a plurality of three-dimensional
structures simultaneously.
4. The method of claim 1 wherein at least one of the depositing
steps comprises electroplating.
5. The method of claim 1 wherein the depositing of the first
material comprises electroplating, the depositing of the second
material comprises electroplating, and the depositing of the third
material comprises electroplating.
6. The method of claim 1 wherein the first of the least two
materials deposited is a structural material.
7. The method of claim 1 wherein the first of the least two
materials deposited is a sacrificial material.
8. The method of claim 1 wherein the given one of the layers
comprises at least two layers.
9. An electroplating method for fabricating a multi-layer
three-dimensional structure, comprising: (A) forming a first layer
comprising depositing at least a first structural material and at
least a first sacrificial material and planarizing the at least one
deposited first structural material and the at least one deposited
first sacrificial material to set a boundary level of the first
layer; (B) forming additional layers with an initial additional
layer formed on and adhered to the first layer and with subsequent
additional layers formed on and adhered to previously formed
additional layers, wherein the forming of each additional layer
comprises depositing at least one additional structural material
and depositing at least one additional sacrificial material and
planarizing the at least one deposited additional structural
material and the at least one additional sacrificial material to
set a boundary level for each additional layer; (C) after forming
the plurality of successive layers, etching away a portion of the
sacrificial material from multiple layers of the structural
material to reveal a portion of the three-dimensional structures,
wherein the steps of depositing and of planarizing during forming
of a given one of the layers comprises: (i) applying a 1st
patternable mold material (PMM) on the layer; (ii) patterning the
1st PMM to form a 1st pattern; (iii) depositing a 1st material in
the 1st pattern; (iv) removing the 1st PMM to expose areas of the
layer not having the 1st material deposited thereon; (v) depositing
a 2nd PMM over the layer; (vi) patterning the 2nd PMM to form a 2nd
pattern, the 2nd pattern including an aperture adjacent to the 1st
material and exposing a top portion of the 1st material; (vii)
depositing a 2nd material in the 2nd pattern formed and over the
exposed top portion of the 1st material; (viii) removing the 2nd
PMM to expose areas of the layer not having the 1st or 2nd
materials deposited thereon; (ix) depositing a third material over
the 1st and 2nd materials and over the exposed areas of the layer;
and (x) planarizing the deposited first--third materials to set a
boundary level for the given layer, and wherein at least one of the
first--third materials is a structural material and at least one of
the first--third materials is a sacrificial material.
10. The method of claim 9 wherein the PMM is a photoresist.
11. The method of claim 9 wherein the forming the three-dimensional
structure comprises the forming of a plurality of three-dimensional
structures simultaneously.
12. The method of claim 9 wherein at least one of the depositing
steps comprises electroplating.
13. The method of claim 9 wherein the depositing of the first
material comprises electroplating, the depositing of the second
material comprises electroplating, and the depositing of the third
material comprises electroplating.
14. The method of claim 9 wherein the given one of the layers
comprises at least two layers.
15. An electroplating method for fabricating a multi-layer
three-dimensional structure, comprising: (A) forming a first layer
comprising depositing at least a first structural material and at
least a first sacrificial material and planarizing the at least one
deposited first structural material and the at least one deposited
first sacrificial material to set a boundary level of the first
layer; (B) forming additional layers with an initial additional
layer formed on and adhered to the first layer and with subsequent
additional layers formed on and adhered to previously formed
additional layers, wherein the forming of each additional layer
comprises depositing at least one additional structural material
and depositing at least one additional sacrificial material and
planarizing the at least one deposited additional structural
material and the at least one additional sacrificial material to
set a boundary level for each additional layer; (C) after forming
the plurality of successive layers, etching away a portion of the
sacrificial material from multiple layers of the structural
material to reveal a portion of the three-dimensional structures,
wherein the steps of depositing and of planarizing during forming
of a given one of the layers comprises depositing first, second and
third materials wherein a patternable mold material (PMM) is formed
over the 1st deposited material and is patterned to form an
aperture adjacent to the 1st material, the aperture exposing a side
portion and a top portion of the 1st material and wherein the
aperture receives the second material during depositing of the
second material.
16. The method of claim 15 wherein the PMM is a photoresist.
17. The method of claim 15 wherein the forming the
three-dimensional structure comprises the forming of a plurality of
three-dimensional structures simultaneously.
18. The method of claim 15 wherein at least one of the depositing
steps comprises electroplating.
19. The method of claim 15 wherein the depositing of the first
material comprises electroplating, the depositing of the second
material comprises electroplating, and the depositing of the third
material comprises electroplating.
20. The method of claim 15 wherein the given one of the layers
comprises at least two layers.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 13/206,133 (Microfabrica Docket No.
P-US098-C-MF), filed Aug. 9, 2011. The '133 application is a
continuation of U.S. patent application Ser. No. 12/479,638
(Microfabrica Docket No. P-US098-B-MF), filed Jun. 5, 2009. The
'638 application is a divisional of U.S. patent application Ser.
No. 10/841,272 (US098-A), filed May 7, 2004 which in turn claims
benefit of U.S. Provisional Application Nos. 60/468,741 and
60/474,625 filed on May 7, 2003 and May 29, 2003, respectively.
These referenced applications are hereby incorporated herein by
reference as if set forth in full herein.
FIELD OF THE INVENTION
[0002] Embodiments of the invention relate generally to the field
of electrochemical fabrication and the associated formation of
three-dimensional structures (e.g. microscale or mesoscale
structures). In particular, they relate to the formation of such
structures using patterned masks that are temporarily adhered to
substrates or to previously formed deposits that may be used for
performing selective patterning of or on the substrates or
previously deposited material.
BACKGROUND OF THE INVENTION
[0003] A technique for forming three-dimensional structures (e.g.
parts, components, devices, and the like) from a plurality of
adhered layers was invented by Adam L. Cohen and is known as
Electrochemical Fabrication. It is being commercially pursued by
Microfabrica.RTM. Inc. of Van Nuys, Calif. under the name
EFAB.RTM.. This technique was described in U.S. Pat. No. 6,027,630,
issued on Feb. 22, 2000. This electrochemical deposition technique
allows the selective deposition of a material using a unique
masking technique that involves the use of a mask that includes
patterned conformable material on a support structure that is
independent of the substrate onto which plating will occur. When
desiring to perform an electrodeposition using the mask, the
conformable portion of the mask is brought into contact with a
substrate while in the presence of a plating solution such that the
contact of the conformable portion of the mask to the substrate
inhibits deposition at selected locations. For convenience, these
masks might be generically called conformable contact masks; the
masking technique may be generically called a conformable contact
mask plating process. More specifically, in the terminology of
Microfabrica.RTM. Inc. of Van Nuys, Calif. such masks have come to
be known as INSTANT MASKS.TM. and the process known as INSTANT
MASKING or INSTANT MASK.TM. plating. Selective depositions using
conformable contact mask plating may be used to form single layers
of material or may be used to form multi-layer structures. The
teachings of the '630 patent are hereby incorporated herein by
reference as if set forth in full herein.
[0004] Since the filing of the patent application that led to the
above noted patent, various papers about conformable contact mask
plating (i.e. INSTANT MASKING) and electrochemical fabrication have
been published: [0005] (1) A. Cohen, G. Zhang, F. Tseng, F.
Mansfeld, U. Frodis and P. Will, "EFAB: Batch production of
functional, fully-dense metal parts with micro-scale features",
Proc. 9th Solid Freeform Fabrication, The University of Texas at
Austin, p161, Aug. 1998. [0006] (2) A. Cohen, G. Zhang, F. Tseng,
F. Mansfeld, U. Frodis and P. Will, "EFAB: Rapid, Low-Cost Desktop
Micromachining of High Aspect Ratio True 3-D MEMS", Proc. 12th IEEE
Micro Electro Mechanical Systems Workshop, IEEE, p244, Jan 1999.
[0007] (3) A. Cohen, "3-D Micromachining by Electrochemical
Fabrication", Micromachine Devices, March 1999. [0008] (4) G.
Zhang, A. Cohen, U. Frodis, F. Tseng, F. Mansfeld, and P. Will,
"EFAB: Rapid Desktop Manufacturing of True 3-D Microstructures",
Proc. 2nd International Conference on Integrated
MicroNanotechnology for Space Applications, The Aerospace Co., Apr.
1999. [0009] (5) F. Tseng, U. Frodis, G. Zhang, A. Cohen, F.
Mansfeld, and P. Will, "EFAB: High Aspect Ratio, Arbitrary 3-D
Metal Microstructures using a Low-Cost Automated Batch Process",
3rd International Workshop on High Aspect Ratio MicroStructure
Technology (HARMST'99), June 1999. [0010] (6) A. Cohen, U. Frodis,
F. Tseng, G. Zhang, F. Mansfeld, and P. Will, "EFAB: Low-Cost,
Automated Electrochemical Batch Fabrication of Arbitrary 3-D
Microstructures", Micromachining and Microfabrication Process
Technology, SPIE 1999 Symposium on Micromachining and
Microfabrication, September 1999. [0011] (7) F. Tseng, G. Zhang, U.
Frodis, A. Cohen, F. Mansfeld, and P. Will, "EFAB: High Aspect
Ratio, Arbitrary 3-D Metal Microstructures using a Low-Cost
Automated Batch Process", MEMS Symposium, ASME 1999 International
Mechanical Engineering Congress and Exposition, November, 1999.
[0012] (8) A. Cohen, "Electrochemical Fabrication (EFABTM)",
Chapter 19 of The MEMS Handbook, edited by Mohamed Gad-El-Hak, CRC
Press, 2002. [0013] (9) "Microfabrication--Rapid Prototyping's
Killer Application", pages 1-5 of the Rapid Prototyping Report,
CAD/CAM Publishing, Inc., June 1999.
[0014] The disclosures of these nine publications are hereby
incorporated herein by reference as if set forth in full
herein.
[0015] The electrochemical deposition process may be carried out in
a number of different ways as set forth in the above patent and
publications. In one form, this process involves the execution of
three separate operations during the formation of each layer of the
structure that is to be formed: [0016] 1. Selectively depositing at
least one material by electrodeposition upon one or more desired
regions of a substrate. [0017] 2. Then, blanket depositing at least
one additional material by electrodeposition so that the additional
deposit covers both the regions that were previously selectively
deposited onto, and the regions of the substrate that did not
receive any previously applied selective depositions. [0018] 3.
Finally, planarizing the materials deposited during the first and
second operations to produce a smoothed surface of a first layer of
desired thickness having at least one region containing the at
least one material and at least one region containing at least the
one additional material.
[0019] After formation of the first layer, one or more additional
layers may be formed adjacent to the immediately preceding layer
and adhered to the smoothed surface of that preceding layer. These
additional layers are formed by repeating the first through third
operations one or more times wherein the formation of each
subsequent layer treats the previously formed layers and the
initial substrate as a new and thickening substrate.
[0020] Once the formation of all layers has been completed, at
least a portion of at least one of the materials deposited is
generally removed by an etching process to expose or release the
three-dimensional structure that was intended to be formed.
[0021] The preferred method of performing the selective
electrodeposition involved in the first operation is by conformable
contact mask plating. In this type of plating, one or more
conformable contact (CC) masks are first formed. The CC masks
include a support structure onto which a patterned conformable
dielectric material is adhered or formed. The conformable material
for each mask is shaped in accordance with a particular
cross-section of material to be plated. At least one CC mask is
needed for each unique cross-sectional pattern that is to be
plated.
[0022] The support for a CC mask is typically a plate-like
structure formed of a metal that is to be selectively electroplated
and from which material to be plated will be dissolved. In this
typical approach, the support will act as an anode in an
electroplating process. In an alternative approach, the support may
instead be a porous or otherwise perforated material through which
deposition material will pass during an electroplating operation on
its way from a distal anode to a deposition surface. In either
approach, it is possible for CC masks to share a common support,
i.e. the patterns of conformable dielectric material for plating
multiple layers of material may be located in different areas of a
single support structure. When a single support structure contains
multiple plating patterns, the entire structure is referred to as
the CC mask while the individual plating masks may be referred to
as "submasks". In the present application such a distinction will
be made only when relevant to a specific point being made.
[0023] In preparation for performing the selective deposition of
the first operation, the conformable portion of the CC mask is
placed in registration with and pressed against a selected portion
of the substrate (or onto a previously formed layer or onto a
previously deposited portion of a layer) on which deposition is to
occur. The pressing together of the CC mask and substrate occur in
such a way that all openings, in the conformable portions of the CC
mask contain plating solution. The conformable material of the CC
mask that contacts the substrate acts as a barrier to
electrodeposition while the openings in the CC mask that are filled
with electroplating solution act as pathways for transferring
material from an anode (e.g. the CC mask support) to the
non-contacted portions of the substrate (which act as a cathode
during the plating operation) when an appropriate potential and/or
current are supplied.
[0024] An example of a CC mask and CC mask plating are shown in
FIGS. 1A-1C. FIG. 1A shows a side view of a CC mask 508 consisting
of a conformable or deformable (e.g. elastomeric) insulator 510
patterned on an anode 512. The anode has two functions. FIG. 1A
also depicts a substrate 506 separated from mask 508. One is as a
supporting material for the patterned insulator 510 to maintain its
integrity and alignment since the pattern may be topologically
complex (e.g., involving isolated "islands" of insulator material).
The other function is as an anode for the electroplating operation.
CC mask plating selectively deposits material 522 onto a substrate
506 by simply pressing the insulator against the substrate then
electrodepositing material through apertures 526a and 526b in the
insulator as shown in FIG. 1B. After deposition, the CC mask is
separated, preferably non-destructively, from the substrate 506 as
shown in FIG. 1C. The CC mask plating process is distinct from a
"through-mask" plating process in that in a through-mask plating
process the separation of the masking material from the substrate
would occur destructively. As with through-mask plating, CC mask
plating deposits material selectively and simultaneously over the
entire layer. The plated region may consist of one or more isolated
plating regions where these isolated plating regions may belong to
a single structure that is being formed or may belong to multiple
structures that are being formed simultaneously. In CC mask plating
as individual masks are not intentionally destroyed in the removal
process, they may be usable in multiple plating operations.
[0025] Another example of a CC mask and CC mask plating is shown in
FIGS. 1D-1F. FIG. 1D shows an anode 512' separated from a mask 508'
that includes a patterned conformable material 510' and a support
structure 520. FIG. 1D also depicts substrate 506 separated from
the mask 508'. FIG. 1E illustrates the mask 508' being brought into
contact with the substrate 506. FIG. 1F illustrates the deposit
522' that results from conducting a current from the anode 512' to
the substrate 506. FIG. 1G illustrates the deposit 522' on
substrate 506 after separation from mask 508'. In this example, an
appropriate electrolyte is located between the substrate 506 and
the anode 512' and a current of ions coming from one or both of the
solution and the anode are conducted through the opening in the
mask to the substrate where material is deposited. This type of
mask may be referred to as an anodeless INSTANT MASK.TM. (AIM) or
as an anodeless conformable contact (ACC) mask.
[0026] Unlike through-mask plating, CC mask plating allows CC masks
to be formed completely separate from the fabrication of the
substrate on which plating is to occur (e.g. separate from a
three-dimensional (3D) structure that is being formed). CC masks
may be formed in a variety of ways, for example, a
photolithographic process may be used. All masks can be generated
simultaneously, prior to structure fabrication rather than during
it. This separation makes possible a simple, low-cost, automated,
self-contained, and internally-clean "desktop factory" that can be
installed almost anywhere to fabricate 3D structures, leaving any
required clean room processes, such as photolithography to be
performed by service bureaus or the like.
[0027] An example of the electrochemical fabrication process
discussed above is illustrated in FIGS. 2A-2F. These figures show
that the process involves deposition of a first material 502 which
is a sacrificial material and a second material 504 which is a
structural material. The CC mask 508, in this example, includes a
patterned conformable material (e.g. an elastomeric dielectric
material) 510 and a support 512 which is made from deposition
material 502. The conformal portion of the CC mask is pressed
against substrate 506 with a plating solution 514 located within
the openings 516 in the conformable material 510. An electric
current, from power supply 518, is then passed through the plating
solution 514 via (a) support 512 which doubles as an anode and (b)
substrate 506 which doubles as a cathode. FIG. 2A, illustrates that
the passing of current causes material 502 within the plating
solution and material 502 from the anode 512 to be selectively
transferred to and plated on the cathode 506. After electroplating
the first deposition material 502 onto the substrate 506 using CC
mask 508, the CC mask 508 is removed as shown in FIG. 2B. FIG. 2C
depicts the second deposition material 504 as having been
blanket-deposited (i.e. non-selectively deposited) over the
previously deposited first deposition material 502 as well as over
the other portions of the substrate 506. The blanket deposition
occurs by electroplating from an anode (not shown), composed of the
second material, through an appropriate plating solution (not
shown), and to the cathode/substrate 506. The entire two-material
layer is then planarized to achieve precise thickness and flatness
as shown in FIG. 2D. After repetition of this process for all
layers, the multi-layer structure 520 formed of the second material
504 (i.e. structural material) is embedded in first material 502
(i.e. sacrificial material) as shown in FIG. 2E. The embedded
structure is etched to yield the desired device, i.e. structure
520, as shown in FIG. 2F.
[0028] Various components of an exemplary manual electrochemical
fabrication system 532 are shown in FIGS. 3A-3C. The system 532
consists of several subsystems 534, 536, 538, and 540. The
substrate holding subsystem 534 is depicted in the upper portions
of each of FIGS. 3A to 3C and includes several components: (1) a
carrier 548, (2) a metal substrate 506 onto which the layers are
deposited, and (3) a linear slide 542 capable of moving the
substrate 506 up and down relative to the carrier 548 in response
to drive force from actuator 544. Subsystem 534 also includes an
indicator 546 for measuring differences in vertical position of the
substrate which may be used in setting or determining layer
thicknesses and/or deposition thicknesses. The subsystem 534
further includes feet 568 for carrier 548 which can be precisely
mounted on subsystem 536.
[0029] The CC mask subsystem 536 shown in the lower portion of FIG.
3A includes several components: (1) a CC mask 508 that is actually
made up of a number of CC masks (i.e. submasks) that share a common
support/anode 512, (2) precision X-stage 554, (3) precision Y-stage
556, (4) frame 572 on which the feet 568 of subsystem 534 can
mount, and (5) a tank 558 for containing the electrolyte 516.
Subsystems 534 and 536 also include appropriate electrical
connections (not shown) for connecting to an appropriate power
source for driving the CC masking process.
[0030] The blanket deposition subsystem 538 is shown in the lower
portion of FIG. 3B and includes several components: (1) an anode
562, (2) an electrolyte tank 564 for holding plating solution 566,
and (3) frame 574 on which the feet 568 of subsystem 534 may sit.
Subsystem 538 also includes appropriate electrical connections (not
shown) for connecting the anode to an appropriate power supply for
driving the blanket deposition process.
[0031] The planarization subsystem 540 is shown in the lower
portion of FIG. 3C and includes a lapping plate 552 and associated
motion and control systems (not shown) for planarizing the
depositions.
[0032] In addition to teaching the use of CC masks for
electrodeposition purposes, the '630 patent also teaches that the
CC masks may be placed against a substrate with the polarity of the
voltage reversed and material may thereby be selectively removed
from the substrate. It indicates that such removal processes can be
used to selectively etch, engrave, and polish a substrate, e.g., a
plaque.
[0033] The '630 patent further indicates that the electroplating
methods and articles disclosed therein allow fabrication of devices
from thin layers of materials such as, e.g., metals, polymers,
ceramics, and semiconductor materials. It further indicates that
although the electroplating embodiments described therein have been
described with respect to the use of two metals, a variety of
materials, e.g., polymers, ceramics and semiconductor materials,
and any number of metals can be deposited either by the
electroplating methods therein, or in separate processes that occur
throughout the electroplating method. It indicates that a thin
plating base can be deposited, e.g., by sputtering, over a deposit
that is insufficiently conductive (e.g., an insulating layer) so as
to enable subsequent electroplating. It also indicates that
multiple support materials (i.e. sacrificial materials) can be
included in the electroplated element allowing selective removal of
the support materials.
[0034] Another method for forming microstructures from
electroplated metals (i.e. using electrochemical fabrication
techniques) is taught in U.S. Pat. No. 5,190,637 to Henry Guckel,
entitled "Formation of Microstructures by Multiple Level Deep X-ray
Lithography with Sacrificial Metal layers". This patent teaches the
formation of metal structure utilizing mask exposures. A first
layer of a primary metal is electroplated onto an exposed plating
base to fill a void in a photoresist, the photoresist is then
removed and a secondary metal is electroplated over the first layer
and over the plating base. The exposed surface of the secondary
metal is then machined down to a height which exposes the first
metal to produce a flat uniform surface extending across the both
the primary and secondary metals. Formation of a second layer may
then begin by applying a photoresist layer over the first layer and
then repeating the process used to produce the first layer. The
process is then repeated until the entire structure is formed and
the secondary metal is removed by etching. The photoresist is
formed over the plating base or previous layer by casting and the
voids in the photoresist are formed by exposure of the photoresist
through a patterned mask via X-rays or UV radiation.
[0035] Further teachings concerning the formation of
microstructures from electroplated metals (i.e. using
electrochemical fabrication techniques) is taught in U.S. Pat. No.
5,718,618 by Henry Guckel, entitled "Lapping and Polishing Method
and Apparatus for Planarizing Photoresist and Metal Microstructure
Layers". This patent teaches a method and apparatus for planarizing
photoresist and/or metal microstructure layers. Planarization is
achieved by removing material from a workpiece by lapping using a
diamond containing lapping slurry. A lapping machine is furnished
with a lapping plate made of a soft metal material. The lapping
plate is furnished with ridges of controlled height using a diamond
conditioning ring with a specified grit size. Free diamonds in a
liquid slurry are then sprayed onto the plate and embedded therein
by a second conditioning ring. After the lapping plate is
conditioned, the piece to be lapped is mounted on the lapping
plate. A vacuum hold fixture or flat steel or glass mounting plate
may be used. During lapping, additional diamond slurry is sprayed
onto the lapping plate and driven into the plate by a ceramic
conditioning ring. The size of diamonds in the diamond slurry is
selected to control the shear forces applied to the surface being
lapped and to achieve a desired surface finish. Polishing, using a
cloth covered hard metal polishing plate and loose diamond slurry,
may be employed after lapping to provide a smooth optical surface
finish. The lapping and polishing method and apparatus described
may be used for z-dimension height control, re-planarization, and
surface finishing of precise single or multiple level
photoresist-metal layers, or of individual preformed photoresist
sheets or laminates thereof.
[0036] Further teachings concerning the formation of
microstructures from electroplated metals is taught in U.S. Pat.
Nos. 5,378,583, 5,496,668, and 5,576,147 by Henry Guckel, and each
entitled "Formation of Microstructures Using a Preformed
Photoresist Sheet". These patents teach the formation of
microstructures using a preformed sheet of photoresist, such as
polymethylmethacrylate (PMMA), which is strain free, and that may
be milled down before or after adherence to a substrate to a
desired thickness. The photoresist is patterned by exposure through
a mask to radiation, such as X-rays, and developed using a
developer to remove the photoresist material which has been
rendered susceptible to the developer. Micrometal structures may be
formed by electroplating metal into the areas from which the
photoresist has been removed. The photoresist itself may form
useful microstructures, and can be removed from the substrate by
utilizing a release layer between the substrate and the preformed
sheet which can be removed by a remover which does not affect the
photoresist. Multiple layers of patterned photoresist can be built
up to allow complex three dimensional microstructures to be
formed.
[0037] Further teachings concerning the formation of
microstructures from electroplated metals (i.e. using
electrochemical fabrication techniques) is taught in US Patent
(Another method for forming microstructures from electroplated
metals (i.e. using electrochemical fabrication techniques) is
taught in U.S. Pat. Nos. 5,866,281 and 5,908,719 by Henry Guckel,
both entitled "Alignment Method for Multi-Level Deep X-Ray
Lithography Utilizing Alignment Holes and Posts". These patents
teach a procedure for achieving accurate alignment between an X-ray
mask and a device substrate for the fabrication of multi-layer
microstructures. A first photoresist layer on the substrate is
patterned by a first X-ray mask to include first alignment holes
along with a first layer microstructure pattern. Mask photoresist
layers are attached to second and subsequent masks that are used to
pattern additional photoresist layers attached to the
microstructure device substrate. The mask photoresist layers are
patterned to include mask alignment holes that correspond in
geometry to the first alignment holes in the first photoresist
layer on the device substrate. Alignment between a second mask and
the first photoresist layer is achieved by assembly of the second
mask onto the first photoresist layer using alignment posts placed
in the first alignment holes in the first photoresist layer that
penetrate into the mask alignment holes in the mask photoresist
layers. The alignment procedure is particularly applicable to the
fabrication of multi-layer metal microstructures using deep X-ray
lithography and electroplating. The alignment procedure may be
extended to multiple photoresist layers and larger device heights
using spacer photoresist sheets between subsequent masks and the
first photoresist layer that are joined together using alignment
posts.
[0038] Even though electrochemical fabrication methods as taught
and practiced to date, have greatly enhanced the capabilities of
microfabrication, and in particular added greatly to the number of
metal layers that can be incorporated into a structure,
electrochemical fabrication can still benefit from improved methods
and apparatus for forming multi-layer structures.
SUMMARY OF THE DISCLOSURE
[0039] It is an object of some aspects of the invention to provide
enhanced masking materials for use in electrochemically fabricating
multi-layer structures.
[0040] It is an object of some aspects of the invention to provide
enhanced techniques for electrochemically fabricating multi-layer
structures that include more than two materials on at least some
layers.
[0041] It is an object of some aspects of the invention to reduce
costs of electrochemically fabricating multi-layer structures.
[0042] It is an object of some aspects of the invention to provide
more reliable electrochemically fabricated multi-layer
structures.
[0043] It is an object of some aspects of the invention to provide
electrochemically fabricated multi-layer structures having improved
structural properties.
[0044] It is an object of some aspects of the invention to reduce
the fabrication time of producing electrochemically fabricated
multi-layer structures.
[0045] Other objects and advantages of various aspects of the
invention will be apparent to those of skill in the art upon review
of the teachings herein. The various aspects of the invention, set
forth explicitly herein or otherwise ascertained from the teachings
herein, may address any one of the above objects alone or in
combination, or alternatively it may not address any of the objects
set forth above but instead address some other object of the
invention which may be ascertained from the teachings herein. It is
not intended that all of these objects be addressed by any single
aspect of the invention even though that may be the case with
regard to some aspects.
[0046] In a first aspect of the invention a process for forming a
multilayer three-dimensional structure, comprising: (a) forming and
adhering a layer of material to a substrate or previously formed
layer; and (b) repeating the forming and adhering operation of (a)
a plurality of times to build up a three-dimensional structure from
a plurality of adhered layers, where successive layers are adhered
to previously formed layers; wherein the formation of at least one
layer comprises: (i) forming and adhering a desired pattern of
masking material on the substrate or previously formed layer,
wherein the patterning of the masking material results in at least
one void in the material that exposes a portion of the substrate or
of a previously formed layer; (ii) depositing a conductive material
into the at least one void in the masking material; and wherein the
masking material comprises a dry film photoresist.
[0047] In a second aspect of the invention a carrier for holding a
substrate, the carrier including a carrier body being perforated by
at least one aperture formed through the carrier body, wherein the
substrate is bonded to the carrier body by a material formed in the
at least one aperture.
[0048] In a third aspect of the invention a carrier for holding a
substrate during formation of at least one layer of material on the
substrate, the carrier including a carrier body having a fixed
reference surface for controlling a thickness of the at least one
layer of material formed on the substrate.
[0049] In a fourth aspect of the invention a carrier for holding a
substrate during formation of one or more layers of material on the
substrate, the carrier including a carrier body having a surface
that provides a reference for measuring a thickness of the one or
more layers of material formed on the substrate.
[0050] In a fifth aspect of the invention a system for
electrodepositing layers of material on a substrate, the system
including: an electrodeposition tank having electrodeposition bath
therein; a carrier acting as a first electrode having a first
polarity, the carrier having a carrier body to which the substrate
is electrically connected, the substrate being immersed in the
electrodeposition tank; a second electrode having a second polarity
opposite from the first polarity, the second electrode being
immersed in the electrodeposition tank; and a power source
electrically connected to the carrier and the second electrode such
that material from the second electrode is electrodeposited onto
the substrate through the electrodeposition bath.
[0051] In a sixth aspect of the invention a system for controlling
thickness of layers formed on a substrate, including: a carrier for
holding the substrate during formation of one or more layers of
material on the substrate, the carrier including a carrier body
having a surface that provides a reference for measuring a
thickness of the one or more layers of material formed on the
substrate; and a planarization fixture for supporting the carrier
body during planarization of the one or more layers of material,
the planarization fixture having at least one surface adapted to
mate with the reference surface of the carrier body such that
surfaces of the one or more layers of material formed on the
substrate are parallel to the reference surface after
planarization.
[0052] In a seventh aspect of the invention a method for forming
one or more layers of material on a substrate, including providing
a carrier for holding the substrate during formation of the one or
more layers of material on the substrate, the carrier including a
carrier body having a surface providing a reference for measuring a
thickness of the one or more layers of material formed on the
substrate.
[0053] In an eighth aspect of the invention a method for forming
one or more layers of material on a layer formation surface of a
substrate, including providing a carrier for holding the substrate
during formation of the one or more layers, the carrier including a
carrier body having a surface that is substantially coplanar with
the layer formation surface.
[0054] In a ninth aspect of the invention an imaging system for
target alignment, including: a first imaging device for focusing on
a first target to produce a first image; a second imaging device
for focusing on a second target to produce a second image; and
means for comparing the first and second images to determine a
degree of misalignment between the first and second targets.
[0055] In a tenth aspect of the invention a method for aligning
targets, including: providing a first imaging device for focusing
on a first target to produce a first image; providing a second
imaging device for focusing on a second target to produce a second
image; and comparing the first and second images to determine a
degree of misalignment between the first and second targets.
[0056] In an eleventh aspect of the invention a method for
determining a priority for forming a sacrificial material and a
structural material on a substrate, including: (a) analyzing
features to be formed on the substrate; (b) determining whether a
feature to be formed on the substrate has a predefined
characteristic; (c) determining whether a feature determined in (b)
to have the predefined characteristic is a positive feature or a
negative feature; (d) forming the structural material first if it
is determined in (c) that the feature is a negative feature; and
(e) forming the sacrificial material first if it is determined in
(c) that the feature is a positive feature.
[0057] In a twelfth aspect of the invention a method for forming
both small positive and negative features in the same layer of a
substrate, including: (a) depositing a first patternable mold
material on the layer; (b) patterning the first patternable mold
material to form a first pattern; (c) depositing a first material
in the first pattern formed in (b); (d) removing the first
patternable mold material to expose areas of the layer not having
the first material deposited thereon; (e) depositing a second
patternable mold material over the layer; (f) patterning the second
patternable mold material to form a second pattern; (g) depositing
a second material in the second pattern formed in (f); (h) removing
the second patternable mold material to expose areas of the layer
not having the first or second materials deposited thereon; (i)
blanket depositing the first material over the second material and
the exposed areas of the layer; and (j) planarizing the layer.
[0058] In a thirteenth aspect of the invention a method for forming
more than two materials on the same layer, including: (a)
depositing a first patternable mold material on the layer; (b)
patterning the first patternable mold material to form a first
pattern; (c) depositing a first material in the first pattern
formed in (b); (d) removing the first patternable mold material to
expose areas of the layer not having the first material deposited
thereon; (e) depositing a second patternable mold material over the
layer; (f) patterning the second patternable mold material to form
a second pattern; (g) depositing a second material in the second
pattern formed in (f); (h) removing the second patternable mold
material to expose areas of the layer not having the first or
second materials deposited thereon; (i) blanket depositing a third
material over the second material and the exposed areas of the
layer; and (j) planarizing the layer.
[0059] In a fourteenth aspect of the invention a method for forming
more than two materials on the same layer wherein two or more
different materials are adjacent to each other, including: (a)
depositing a first patternable mold material on the layer; (b)
patterning the first patternable mold material to form a first
pattern; (c) depositing a first material in the first pattern
formed in (b); (d) removing the first patternable mold material to
expose areas of the layer not having the first material deposited
thereon; (e) depositing a second patternable mold material over the
layer; (f) patterning the second patternable mold material to form
a second pattern, the second pattern including an aperture adjacent
to the first material and exposing a top portion of the first
material; (g) depositing a second material in the second pattern
formed in (f) and over the exposed top portion of the first
material; (h) removing the second patternable mold material to
expose areas of the layer not having the first or second materials
deposited thereon; (i) blanket depositing a third material over the
first and second materials and over the exposed areas of the layer;
and (j) planarizing the layer.
[0060] In a fifteenth aspect of the invention a method for forming
more than two materials on the same layer wherein two or more
different materials are adjacent to each other, including: (a)
depositing a first patternable mold material on the layer; (b)
patterning the first patternable mold material to form a first
pattern; (c) depositing a first material in the first pattern
formed in (b); (d) depositing a second patternable mold material
over the first material and the first patternable mold material;
(e) patterning the first and second patternable mold materials to
form a second pattern, the second pattern including an aperture
adjacent to the first material and exposing a top portion of the
first material; (f) depositing a second material in the second
pattern formed in (e) and over the exposed top portion of the first
material; (g) removing the first and second patternable mold
materials to expose areas of the layer not having the first or
second materials deposited thereon; (h) blanket depositing a third
material over the first and second materials and over the exposed
areas of the layer; and (i) planarizing the layer.
[0061] In a sixteenth aspect of the invention a method for forming
more than two materials on the same layer wherein two or more
different materials are adjacent to each other, including: (a)
depositing a patternable mold material on the layer; (b) patterning
the patternable mold material a first time to form a first pattern;
(c) depositing a first material in the first pattern formed in (b);
(d) patterning the patternable mold material a second time to form
a second pattern, the second pattern including an aperture adjacent
to the first material; (e) depositing a second material in the
second pattern formed in (d); (f) removing the patternable mold
material to expose areas of the layer not having the first or
second materials deposited thereon; (g) blanket depositing a third
material over the first and second materials and over the exposed
areas of the layer; and (h) planarizing the layer.
[0062] In a seventeenth aspect of the invention a method for
forming more than two materials on the same layer wherein two or
more different materials are adjacent to each other, including: (a)
forming an ablatable material on the layer; (b) ablating the
ablatable material a first time to form a first pattern; (c)
depositing a first material in the first pattern formed in (b); (d)
ablating the ablatable material a second time to form a second
pattern, the second pattern including an aperture adjacent to the
first material and exposing a top portion of the first material;
(e) depositing a second material in the second pattern formed in
(d) and over the exposed top portion of the first material; (f)
removing the ablatable material to expose areas of the layer not
having the first or second materials deposited thereon; (g) blanket
depositing a third material over the first and second materials and
over the exposed areas of the layer; and (h) planarizing the
layer.
[0063] In an eighteenth aspect of the invention a method for
forming more than two materials on the same layer wherein two or
more different materials are adjacent to each other, including: (a)
depositing a first patternable mold material on the layer; (b)
patterning the first patternable mold material to form a first
pattern; (c) depositing a first material in the first pattern
formed in (b); (d) depositing a second patternable mold material
over the first material and the first patternable mold material;
(e) patterning the first and second patternable mold materials to
form a second pattern, the second pattern including an aperture
adjacent to the first material and exposing a top portion of the
first material.
[0064] In a nineteenth aspect of the invention a method for
preparing a layer having formed thereon a feature consisting of a
first material for deposition of a second material adjacent to the
first material, including: (a) depositing a patternable mold
material over the first material; and (b) patterning the
patternable mold material to form an aperture adjacent to the first
material, the aperture exposing a side portion and a top portion of
the first material.
[0065] In a twentieth aspect of the invention a method for forming
an alignment target on a substrate, including: forming a first
patternable mold material on the substrate; patterning the first
patternable mold material to form a first aperture; forming a first
material in the first aperture to form an alignment target within
the first aperture; removing the first patternable mold material;
forming a second patternable mold material on the substrate so as
to cover the alignment target; and forming the second patternable
mold material to form a second aperture wider than and fully
enclosing the alignment target.
[0066] In a twenty-first aspect of the invention a method for
forming an alignment target, including: providing a substrate
having a non-conductive surface; forming a conductive layer over
the non-conductive surface; and forming a target portion of the
conductive layer such that the target portion is electrically
isolated from the remainder of the conductive layer by the
non-conductive surface.
[0067] In a twenty-second aspect of the invention an alignment
target formed from a conductive layer deposited on a non-conductive
surface of a substrate such that the alignment target is
electrically isolated from the remainder of the conductive layer by
the non-conductive surface.
[0068] In a twenty-third aspect of the invention a method for
forming an alignment target, including: providing a substrate;
forming a non-conductive material on a portion of a surface of the
substrate; forming a conductive layer over the non-conductive
material; and forming a target portion of the conductive layer such
that the target portion is electrically isolated from the remainder
of the conductive layer by the non-conductive material.
[0069] In a twenty-fourth aspect of the invention a method for
electroplating a layer of material on a substrate, including:
forming a conductive layer over a non-conductive surface of the
substrate; forming a target in the conductive layer such that the
target is electrically isolated from the remainder of the
conductive layer by the non-conductive surface of the substrate;
and electroplating the layer of material over the conductive layer
such that the conductive layer is plated and the target is
un-plated.
[0070] In a twenty-fifth aspect of the invention a method for
patterning odd and even layers of patternable material formed
sequentially on a substrate, including: patterning the odd layers
using first photomasks having a first layout of alignment shapes
and new target shapes, the first layout having a first orientation
relative to the substrate; and patterning the even layers using
second photomasks having a second layout of alignment shapes and
new target shapes, the second layout having a second orientation
relative to the substrate different from the first orientation.
[0071] In a twenty-sixth aspect of the invention a photomask used
in patterning layers on a substrate, the photomask including a
plurality of patterns for a corresponding plurality of layers to be
patterned on the substrate, at least two of the plurality of
patterns having orientations different from each other relative to
an orientation of the substrate, each of the different orientations
being alignable with the orientation of the substrate.
[0072] In a twenty-seventh aspect of the invention a method for
selecting a patternable mold material used in patterning a layer
formed on a substrate, including: (a) analyzing geometrical
characteristics of features to be formed on the layer; and (b)
selecting a patternable mold material for patterning the layer
based on the results of the analysis performed in (a).
[0073] In a twenty-eighth aspect of the invention a method for
forming layers on a substrate, including: providing a first
patternable mold material of a first type to be used in forming a
first layer on the substrate; and providing a second patternable
mold material of a second type used in forming a second layer on
the substrate.
[0074] In a twenty-ninth aspect of the invention a template for
carrying a substrate having layers formed thereon, the template
including an upper surface with an aperture formed therein for
receiving the substrate such that an uppermost layer formed on the
substrate is substantially flush with the upper surface.
[0075] In a thirtieth aspect of the invention a method for
laminating layers formed on a substrate, including providing a
template for carrying through a laminator a substrate having layers
formed thereon to be laminated, the template including an upper
surface with an aperture formed therein for receiving the
substrate.
[0076] In a thirty-first aspect of the invention a method for
laminating layers formed on a substrate using a laminator,
including: (a) determining a thermal mass of the layers formed on
the substrate; and (b) adjusting parameters of the laminator based
the thermal mass determined in (a).
[0077] In a thirty-second aspect of the invention a method for
forming layers on a substrate, including: forming a first layer of
a patternable mold material on the substrate; forming at least one
additional layer of the patternable mold material on the first
layer; and patterning the first layer and the at least one
additional layer.
[0078] In a thirty-third aspect of the invention a method for
forming layers on a substrate, including: forming a layer of dry
film resist having a first thickness on a substrate; and thinning
the layer such that the layer has a second thickness less than the
first thickness.
[0079] In a thirty-fourth aspect of the invention a method for
fabricating a multi-layer structure, including patterning at least
one layer of the multi-layer structure using a dry film resist.
[0080] In a thirty-fifth aspect of the invention a method for
fabricating a Microelectromechanical System (MEMS), including
patterning at least one layer used to fabricate the
Microelectromechanical System (MEMS) using a dry film resist.
[0081] In a thirty-sixth aspect of the invention a method for
forming on a surface a layer of material having an object
incorporated therein, the method including: forming a first layer
of patternable mold material on a first surface; forming a first
aperture in the first layer of patternable mold material for
receiving an object; placing the object in the first aperture; and
forming a first material in the first aperture such that the first
material encases the object.
[0082] In a thirty-seventh aspect of the invention a structure
formed on a substrate, including a plurality of layers of
structural material formed one over another, at least one of the
plurality of layers having an object incorporated therein.
[0083] In a thirty-eighth aspect of the invention a structure,
including: a first layer of material formed on a substrate, the
first layer of material having a first aperture formed therein; at
least one object held loosely within the first aperture; and a
second layer of material formed over the first layer of material
for securing the object in the first aperture.
[0084] In a thirty-ninth aspect of the invention a structure,
including: a first layer of material formed on a substrate, the
first layer of material having a track formed therein; a plurality
of objects held loosely within the track; and a second layer of
material formed over the first layer of material for securing the
objects in the track.
[0085] In a fortieth aspect of the invention a method for forming
on a surface a layer of material for incorporating an object
therein, including: forming a first patternable mold material on
the surface; patterning apertures in the first patternable mold
material; depositing a first material into the apertures to form at
least two portions of the first material separated by the first
patternable mold material; removing the first patternable mold
material to form a cavity between the at least two portions of the
first material for receiving the object; forming a second
patternable mold material to provide a barrier against deposition
of a second material into the cavity; depositing the second
material; and removing the second patternable mold material.
[0086] In a forty-first aspect of the invention a method for
forming a structure on a surface, including: building a plurality
of layers on the surface, the plurality of layers including both a
structural material and a sacrificial material; and after building
the plurality of layers, removing the sacrificial material from the
plurality of layers; wherein the sacrificial material is a
patternable mold material.
[0087] In a forty-second aspect of the invention a method for
forming a structure on a surface, including: forming a first layer
of patternable mold material; patterning first apertures in the
first layer of patternable mold material; depositing a first
structural material into the first apertures; forming a second
layer of patternable mold material over the first layer of
patternable mold material and the first structural material;
patterning second apertures into the second layer of patternable
mold material; and depositing a second structural material into the
second apertures.
[0088] In a forty-third aspect of the invention a method for
forming a structure on a surface, including: forming a first layer
of patternable mold material; patterning first apertures in the
first layer of patternable mold material; depositing a first
conductive material into the first apertures; applying a coating of
conductive particles over the first layer of patternable mold
material; forming a second layer of patternable mold material;
patterning second apertures in the second layer of patternable mold
material to expose portions of the coating of conductive particles
and the first conductive material; and depositing a second
conductive material into the second apertures.
[0089] In a forty-fourth aspect of the invention a method for
forming a structure on a surface, including: forming a first layer
of patternable mold material; patterning first apertures in the
first layer of patternable mold material; depositing a first
conductive material into the first apertures; forming a second
layer of patternable mold material; patterning second apertures in
the second layer of patternable mold material to expose areas of
the first layer of patternable mold material and areas of the first
conductive material; depositing a coating of conductive particles
into the second apertures such that they are secured in the exposed
areas of the first layer of patternable mold material; and
depositing a second conductive material into the second
apertures.
[0090] In a forty-fifth aspect of the invention a method for
forming a structure on a surface, including: forming a first layer
of patternable mold material; patterning apertures in the first
layer of patternable mold material; depositing a first metal into
the apertures; removing the first layer of patternable mold
material; and depositing a non-metallic conductive material such
that the non-metallic conductive material electrically couples
portions of the first metal to each other to form a plating base
for plating a second metal.
[0091] In a forty-sixth aspect of the invention a method for
forming a structure on a surface, including: forming a first layer
of patternable mold material having conductive particles dispersed
therein; and driving the conductive particles to an upper surface
of the first layer of patternable mold material to form a plating
surface for plating a subsequent layer of material.
[0092] In a forty-seventh aspect of the invention a method for
forming structures and dicing lanes on a substrate, including:
forming a first layer of patternable mold material on a surface;
patterning first apertures in the first layer of patternable mold
material; forming a first material in the first apertures; and
removing the first layer of patternable mold material to expose
portions of the surface, a plurality of the exposed portions of the
surface functioning as dicing lanes.
[0093] In a forty-eighth aspect of the invention a method for
forming an array of structures, including: forming a first layer of
patternable mold material on a surface; exposing the first layer of
patternable mold material using a first photomask to form a first
pattern of soluble and insoluble portions of the first layer of
patternable mold material, the first pattern for forming an array
of structures having a first number of structures; and exposing the
first pattern using a second photomask different from the first
photomask to form a second pattern of soluble and insoluble
portions of the first layer of patternable mold material from the
first pattern, the second pattern for forming an array of
structures having a second number of structures different from the
first number of structures.
[0094] In a forty-ninth aspect of the invention a method for
forming structures, including: forming a first layer on a surface,
the first layer including first portions of structural material and
first portions of sacrificial material; forming a second layer over
the first layer, the second layer including second portions of
structural material and second portions of sacrificial material,
some of the second portions of structural material being formed
over the first portions of structural material and others of the
second portions of structural material being formed over the first
portions of sacrificial material; and removing the first and second
portions of sacrificial material such that the second portions of
structural material being formed over the first portions of
sacrificial material are also removed.
[0095] In a fiftieth aspect of the invention a method for forming
an array of structures, including exposing a layer of patternable
mold material using a first photomask having a first pattern for
forming an array of structures having a first number of structures
and a second photomask having a second pattern for forming an array
of structures having a second number of structures different from
the first number of structures, the first and second photomasks
being used simultaneously to expose the first layer of patternable
mold material.
[0096] In a fifty-first aspect of the invention a process for
forming a multilayer three-dimensional structure, comprising: (a)
forming and adhering a layer of material to a substrate or
previously formed layer; and (b) repeating the forming and adhering
operation of (a) a plurality of times to build up a
three-dimensional structure from a plurality of adhered layers,
where successive layers are adhered to previously formed layers;
wherein the formation of at least one layer comprises: (i) forming
and adhering a desired pattern of masking material on the substrate
or previously formed layer, wherein the patterning of the masking
material results in at least one void in the material that exposes
a portion of the substrate or of a previously formed layer; (ii)
depositing a conductive material into the at least one void in the
masking material; and wherein the formation of the at least one
layer additionally comprises removing the masking material,
depositing a second material, and planarizing the deposited first
and second materials to a desired height.
[0097] In a fifty-second aspect of the invention a process for
forming a multilayer three-dimensional structure, comprising: (a)
forming and adhering a layer of material to a substrate or
previously formed layer; and (b) repeating the forming and adhering
operation of (a) a plurality of times to build up a
three-dimensional structure from a plurality of adhered layers,
where successive layers are adhered to previously formed layers;
wherein the formation of at least one layer comprises: (i) forming
and adhering a desired pattern of masking material on the substrate
or previously formed layer, wherein the patterning of the masking
material results in at least one void in the material that exposes
a portion of the substrate or of a previously formed layer; (ii)
depositing a conductive material into the at least one void in the
masking material; and wherein the formation of the at least one
layer additionally comprises removing the masking material and
depositing a dielectric material, and wherein the formation of a
subsequent layer comprises depositing a seed layer on at least a
portion of the at least one layer.
[0098] In a fifty-third aspect of the invention a process for
forming a multilayer three-dimensional structure, comprising: (a)
forming and adhering a layer of material to a substrate or
previously formed layer; and (b) repeating the forming and adhering
operation of (a) a plurality of times to build up a
three-dimensional structure from a plurality of adhered layers,
where successive layers are adhered to previously formed layers;
wherein the formation of at least one layer comprises: (i) forming
and adhering a desired pattern of masking material on the substrate
or previously formed layer, wherein the patterning of the masking
material results in at least one void in the material that exposes
a portion of the substrate or of a previously formed layer; (ii)
depositing a conductive material into the at least one void in the
masking material; and wherein the formation of the at least one
layer additionally comprises depositing a seed layer on the
substrate, or previously formed layer, which comprises only
conductive material, prior to forming and adhering the mask
material.
[0099] In a fifty-fourth aspect of the invention a process for
forming a multilayer three-dimensional structure, comprising: (a)
forming and adhering a layer of material to a substrate or
previously formed layer; and (b) repeating the forming and adhering
operation of (a) a plurality of times to build up a
three-dimensional structure from a plurality of adhered layers,
where successive layers are adhered to previously formed layers;
wherein the formation of at least one layer comprises: (i) forming
and adhering a desired pattern of masking material on the substrate
or previously formed layer, wherein the patterning of the masking
material results in at least one void in the material that exposes
a portion of the substrate or of a previously formed layer; (ii)
depositing a conductive material into the at least one void in the
masking material; and wherein the at least one layer, after it is
completed, comprises at least three different materials located in
different lateral positions on the layer.
[0100] In a fifty-fifth aspect of the invention a process for
forming a multilayer three-dimensional structure, comprising: (a)
forming and adhering a layer of material to a substrate or
previously formed layer; and (b) repeating the forming and adhering
operation of (a) a plurality of times to build up a
three-dimensional structure from a plurality of adhered layers,
where successive layers are adhered to previously formed layers;
wherein the formation of at least one layer comprises: (i) forming
and adhering a desired pattern of masking material on the substrate
or previously formed layer, wherein the patterning of the masking
material results in at least one void in the material that exposes
a portion of the substrate or of a previously formed layer; (ii)
depositing a conductive material into the at least one void in the
masking material; and wherein the formation of the at least one
layer additionally comprises optically aligning a position of the
patterning of the dielectric material by using a focused image of
an alignment mark that is located at on least one of (1) the
substrate, (2) a carrier on which the substrate sits, or (3)
previously deposited material that is located on the substrate.
[0101] Further aspects of the invention will be understood by those
of skill in the art upon reviewing the teachings herein. Other
aspects of the invention may involve combinations of the above
noted aspects of the invention and/or addition of various features
of one or more embodiments. Other aspects of the invention may
involve apparatus that are configured to implement one or more of
the above method aspects of the invention. These other aspects of
the invention may provide various combinations of the aspects
presented above as well as provide other configurations,
structures, functional relationships, and processes that have not
been specifically set forth above.
BRIEF DESCRIPTION OF THE DRAWINGS
[0102] FIGS. 1A-1C schematically depict side views of various
stages of a CC mask plating process, while FIGS. 1D-1G
schematically depict side views of various stages of a CC mask
plating process using a different type of CC mask.
[0103] FIGS. 2A-2F schematically depict side views of various
stages of an electrochemical fabrication process as applied to the
formation of a particular structure where a sacrificial material is
selectively deposited while a structural material is blanket
deposited.
[0104] FIGS. 3A-3C schematically depict side views of various
example subassemblies that may be used in manually implementing the
electrochemical fabrication method depicted in FIGS. 2A-2F.
[0105] FIGS. 4A-4I schematically depict the formation of a first
layer of a structure using adhered mask plating where the blanket
deposition of a second material overlays both the openings between
deposition locations of a first material and the first material
itself.
[0106] FIGS. 5A-5II illustrate an apparatus and method, according
to an embodiment of the invention where a carrier is used to hold a
substrate during at least part of the process of forming a
three-dimensional structure.
[0107] FIGS. 6A-6C depict side views of an alternative carrier body
configuration that allows interlocked bonding between the carrier
and a substrate.
[0108] FIGS. 7A-7B each depict a top, side, and perspective view of
a carrier body, respectively, having a conical shaped aperture or
an elongated v-shaped aperture.
[0109] FIG. 8 depicts a side view of rollers of a dry film
laminator along with a sheet of dry film that is wrapped around one
of the rollers and a substrate that will be feed between the
rollers.
[0110] FIGS. 9A and 9B depict perspective views of circular
substrates and rectangular templates for holding the substrates
when being fed into a laminator.
[0111] FIGS. 10A-10B depict sectional side views of the substrate
and template of FIG. 9B along with shims that may be located
beneath the substrate to ensure appropriate matching of the upper
surfaces of the substrate and the template.
[0112] FIGS. 11A-11E depict side views of various stages of an
example process where multiple layers of photoresist are added to a
substrate prior to patterning them.
[0113] FIGS. 12A-12B depict, respectively, examples of a small
positive feature and a small negative feature resulting from a
selective deposition of material.
[0114] FIG. 13 depicts a side view of a narrow feature that exists
in a first deposited material into which a blanket deposited
material does not completely fill as a result, at least in part, of
the aspect ratio (i.e. height/width) of the feature.
[0115] FIGS. 14A-14H depict schematic side views of various states
of a process for forming a narrow positive feature such as that
shown in FIG. 12A.
[0116] FIGS. 15A-15E depict schematic side views of various states
of a process for forming a narrow negative feature such as that
shown in FIG. 12B.
[0117] FIG. 16 provides a flowchart of a process for determining
priority of deposition based on the existence of certain features
on a layer.
[0118] FIGS. 17A-17H depict schematic side views of various states
of a process for forming a layer containing both narrow negative
and narrow positive features where the patternable mold material
cannot generally produce small features of both types.
[0119] FIGS. 18A-18K depict a process for depositing more than two
materials on a single layer.
[0120] FIGS. 19A-19K depict a process of a first exemplary
embodiment for depositing more than two materials on a single layer
where two or more different materials are adjacent to each
other.
[0121] FIGS. 20A-20J depict a process of a second exemplary
embodiment for depositing more than two materials on a single layer
where two or more different materials are adjacent to each
other.
[0122] FIGS. 21A-21I depict a process of a third exemplary
embodiment for depositing more than two materials on a single layer
where two or more different materials are adjacent to each
other.
[0123] FIGS. 22A-22I depict a process of a fourth exemplary
embodiment for depositing more than two materials on a single layer
where two or more different materials may be adjacent to each
other.
[0124] FIGS. 23A-23B depict, respectively, side views of structures
that expand and contract with the formation of successive layers
forming at least part of a multi-layer structure.
[0125] FIGS. 24A-24G depict schematic side views of various states
of a process for forming an expanding structure, such as that shown
in FIG. 23A, where photoresist is exposed in a plurality of layer
operations but where development occurs only after exposure of
multiple layers of photoresist occur and then back filling of the
created void with a structural material occurs.
[0126] FIGS. 25A-25G illustrate an embodiment of a process for
forming a contracting structure like that shown in FIG. 23B.
[0127] FIG. 26 depicts a side view of a plurality of offset
layers.
[0128] FIG. 27 provides a flowchart of a process for analyzing
features on a layer to determine if a seed layer needs to be
deposited.
[0129] FIGS. 28A-28B provide side views of two operations involved
in an embodiment that uses backside alignment to ensure
registration of patterning masks
[0130] FIGS. 29A-29X depict various stages of an embodiment of the
invention where alignment targets may be formed by
electrodepositing material.
[0131] FIGS. 30A-30R depict various stages of an embodiment of the
invention where alignment targets are formed in an adhesion layer
and/or in a seed layer.
[0132] FIG. 31 shows a top view of a substrate, layer, and
alignment targets according to an embodiment of the invention.
[0133] FIGS. 32A-32C show examples, respectively, of an alignment
target that may be located on a previous layer, an alignment target
that may be located on an alignment mask, and an overlaying of the
two.
[0134] FIGS. 33A-33D depict a series of mask and layer alignment
targets that may be used on alternating layers according to some
embodiments of the invention.
[0135] FIGS. 34A-34B depict a substrate, FIG. 34A, having a single
quadrant on which useful structures will be formed and a mask, FIG.
34B, having differently oriented patterns in each of four
quadrants, such that upon each 90.degree. rotation of the mask a
different portion of the photomask may be used in patterning the
substrate which may reduce the net number of photomasks needed to
produce small quantities of structures.
[0136] FIGS. 35A-35B depict how substrate and mask alignment
targets may be aligned upon rotation according to some embodiments
of the invention.
[0137] FIG. 36A-36D, schematically depict side views of various
relationships between a carrier and a substrate that may be used in
some embodiments of the invention.
[0138] FIGS. 37A-37P show a process for incorporating objects
within layers formed on a substrate.
[0139] FIGS. 38A-38P show another embodiment of the invention for
incorporating foreign objects within layers formed on a
substrate.
[0140] FIG. 39 shows a top view of a step in the formation of a
ball bearing structure formed according to some embodiments of the
invention.
[0141] FIG. 40 shows a completed ball bearing structure formed
according to some embodiments of the invention.
[0142] FIGS. 41A-41K show another embodiment of the invention for
incorporating foreign objects within layers formed on a
substrate.
[0143] FIGS. 42A-42P provide a schematic illustration of various
stages of a process for forming multi-layer structures where the
patternable mold material is used as the sacrificial material.
[0144] FIGS. 43A-43R show an alternative embodiment for using
patternable mold material as the sacrificial material.
[0145] FIGS. 44A-44I show another alternative embodiment for using
patternable mold material as the sacrificial material.
[0146] FIGS. 45A-45M show an embodiment of the invention for
building layers on large substrates in such a manner as to minimize
stresses to a large substrate that may result from deposited
materials.
[0147] FIGS. 46A-46Q show an embodiment of the invention for
fabricating customized arrays of devices without needing to use an
entirely new set of photomasks for each customized array
configuration.
[0148] FIGS. 47A-47Q show another embodiment of the invention for
fabricating customized arrays of devices without needing to use a
different set of photomasks for each customized array
configuration.
[0149] FIGS. 48A-48B show a sample multi-element structure which is
formed using a structural material and a sacrificial material and
where the sacrificial material has been removed as shown in FIG.
48B.
[0150] FIGS. 49A-49B show a sample multi-element structure where
individual elements have different lengths before and after removal
of sacrificial material.
[0151] FIGS. 50A-50D show two sample multi-element structures where
individual elements have different lengths before and after removal
of sacrificial material and where a second substrate is added to
the build so as to retain elements of the second structure that
would otherwise have been lost.
[0152] FIGS. 51A-51B illustrate an embodiment similar to that of
FIGS. 49A and 49B with the exception structural material elements
that are to be removed are held together by a bridging
structure.
[0153] FIGS. 52A-52G show an embodiment of the invention for
pre-patterning a patternable mold material on a temporary substrate
before using the temporary substrate to form a pattern for
depositing other materials on a separate substrate.
[0154] FIGS. 53A-53F show another embodiment of the invention for
transferring a pattern from a temporary substrate to a build
substrate.
[0155] FIGS. 54A-54F show another embodiment of the invention for
transferring a pattern from a temporary substrate to a build
substrate.
[0156] FIGS. 55A-55I show an embodiment of the invention for
depositing more than one material in an aperture formed in a
patternable mold material such that a layered deposit of materials
are formed on a single layer.
[0157] FIGS. 56A-56I show an alternative embodiment of the
invention for depositing more than one material in an aperture
formed in a patternable mold material such that a layered deposit
of materials are formed on a single layer.
[0158] FIGS. 57A-57G show an embodiment of the invention for using
a patternable mold material to perform a patterned etch.
[0159] FIGS. 58A-58J show an embodiment of the invention for using
a patternable mold material both to etch a pattern in a first
material and to plate a second material in the etched pattern.
[0160] FIGS. 59A-59I show a further embodiment of the invention for
forming a target on a substrate.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0161] FIGS. 1A-1G, 2A-2F, and 3A-3C illustrate various features of
one form of electrochemical fabrication that are known. Other
electrochemical fabrication techniques are set forth in the '630
patent referenced above, in the various previously incorporated
publications, in various other patents and patent applications
incorporated herein by reference, still others may be derived from
combinations of various approaches described in these publications,
patents, and applications, or are otherwise known or ascertainable
by those of skill in the art from the teachings set forth herein.
All of these techniques may be combined with those of the invention
explicitly set forth herein to yield enhanced embodiments. Still
other embodiments may be derived from combinations of the various
embodiments explicitly set forth herein.
[0162] FIGS. 4A-4I illustrate various stages in the formation of a
multi-layer three-dimensional structure formed using a fabrication
process that involves the deposition of first and second metals on
a layer-by-layer basis so as to build up the structure from a
plurality of adhered layers. In some embodiments, the first and/or
second materials may be electrodeposited (e.g. using electroplating
or electrophoretic deposition) while in some embodiments, the one
or both of the materials may be deposited via an electroless
deposition, via thermal spraying, sputtering, spreading, and the
like. A first metal is deposited to selected locations via openings
in a mask that is adhered to the substrate (which may include
previously deposited materials or layers) while a second metal is
deposited so as to fill voids in the layer located between
locations of the first metal. Successive layers are deposited on
immediately preceding layers to build up desired structures from
multiple adhered layers.
[0163] In FIG. 4A, a side view of a substrate 582 is shown, onto
which patternable photoresist 584 (i.e. a patternable mold
material) is applied as shown in FIG. 4B. The photoresist may be
supplied and applied in the form of a liquid or in the form of a
dry film. Photoresists may be of the negative or positive types. In
FIG. 4C, a pattern of resist is shown that results from the curing
(if applied as a liquid) or adhering (if applied as a dry film),
exposing (e.g. via UV radiation applied through a photomask), and
developing of the resist. The patterning of the photoresist 584
results in openings or apertures 92A-92C extending from a surface
586 of the photoresist through the thickness of the photoresist to
surface 588 of the substrate 582.
[0164] In FIG. 4D, a metal 594 (e.g. copper, silver, an alloy of
copper, or the like) is shown as having been deposited (e.g.
electroplated) into the openings 592(a)-592(c). In FIG. 4E, the
photoresist has been removed (i.e. chemically stripped) from the
substrate to expose regions of the substrate 582 which are not
covered with the first metal 594. In FIG. 4F, a second metal 596
(e.g., nickel, gold, tin, zinc, an alloy of nickel, or the like) is
shown as having been blanket deposited (e.g. electroplated) over
the entire exposed portions of the substrate 582 (which is
conductive) and over the first metal 594 (which is also
conductive). FIG. 4G depicts the completed first layer of the
structure which has resulted from the planarization of the first
and second metals down to a height that exposes the first metal and
sets a thickness for the first layer. The planarization operations
may also set the flatness of the formed layer and its surface
finish.
[0165] FIG. 4H shows an example of the result of repeating the
process steps shown in FIGS. 4B-4G several times, with a different
masking pattern on each layer, to form a multi-layer structure.
Each layer includes two metals. For most applications, one of these
metals is removed as shown in FIG. 4I to yield a desired 3-D
structure 598 (e.g. component or device).
[0166] In some alternative embodiments, as will be discussed herein
later, more than two materials may be used. In such embodiments,
each material may be a metal, or some of them may be dielectrics.
In various embodiments, one or more of the materials used in
building up layers of the structure may be a structural material
(i.e. a material that will form part of the structure itself) while
one or more of the other materials may be a sacrificial material
(i.e. a material that will be removed prior to putting the
structure (e.g. object, device, or component) to its intended
use.
[0167] Various embodiments of some aspects of the invention are
directed to formation of three-dimensional structures from
materials some of which may be electrodeposited. Some of these
structures may be formed form a single layer of one or more
deposited materials while others are formed from a plurality of
layers of deposited materials (e.g. 2 or more layers, more
preferably five or more layers, and most preferably ten or more
layers). In some embodiments structures having features positioned
with micron level precision and minimum features size on the order
of tens of microns are to be formed. In other embodiments
structures with less precise feature placement and/or larger
minimum features may be formed. In still other embodiments, higher
precision and smaller minimum feature sizes may be desirable.
[0168] Various embodiments to be discussed herein after may be
focused primarily on a particular type of masking technique for
selective patterning of deposited materials. However, each
embodiment may have alternatives that are implementable with other
patterning techniques. For example, some embodiments may have
alternatives that may use contact masks and contact masking
operations, such as conformable contact masks as described above,
or non-conformable masks and masking operations (i.e. masks and
operations based on masks whose contact surfaces are not
significantly conformable). Other alternatives may make use of
proximity masks and masking operations (i.e. operations that use
masks that at least partially selectively shield a substrate by
their proximity to the substrate even if contact is not made).
Still other alternatives may make use of various types of adhered
masks and masking operations (masks and operations that use masks
that are adhered to a substrate onto which selective deposition or
etching is to occur as opposed to only being contacted to it).
Adhered masks may be formed in a number of ways including, for
example (1) by application of a photoresist, selective exposure of
the photoresist, and then development of the photoresist, (2)
selective transfer of pre-patterned masking material, and/or (3)
direct formation of masks from computer controlled depositions of
material. Selective patterning using masks may occur by depositing
a selected material into voids or openings in the masks or it occur
by selectively etching a surface of an already deposited material
using the mask. In other applications, selective patterning may not
involve a significant height of deposition of material or
significant depth of etching of material but instead may involve
treating a surface in a selective manner, e.g. selective
microetching of a surface (e.g. to improve adhesion between it and
a material), selective oxidization of a surface (e.g. to change its
conductivity), selective chemical treatment of a surface (e.g. in
preparation for an electroless deposition), and the like.
[0169] FIGS. 5A-5II illustrate schematic side views of the states
of the process and apparatus components involved in forming a
sample structure according to a first embodiment of the invention.
In this embodiment, a carrier is provided for carrying a substrate
on which layers of material will be formed during fabrication of a
structure.
[0170] FIG. 36A-36D, schematically depict side views of various
relationships between a carrier and a substrate that may be used in
some embodiments of the invention. FIG. 36A depicts a substrate
without a carrier and thus indicates that in some embodiments of
the invention, a substrate 192 may be used without a carrier. FIGS.
36B-36C depict some other relationships that may exist in other
embodiments. In some embodiments a carrier 194 may have the same
size as the substrate 192, as shown in FIG. 36B. Other embodiments
may use a carrier 196 that is larger than the substrate 192, as
shown in FIG. 36C. Still other embodiments may be used or include a
carrier 198 that has a recess for receiving substrate 192, as shown
in FIG. 36D.
[0171] Turning back to FIG. 5A, a carrier 1 may include a carrier
body 2 having a highly planar surface 3. Carrier 1 may further
include two or more alignment target inserts 5 covered by removable
protective covers 7. Carrier body 2 may further include pressing
means 9 for applying pressure to a substrate 25 as shown in FIG.
5C. According to some embodiments of the invention, the pressing
means 109 may be any suitable means for applying pressure such as,
but not limited to, one or more springs, as shown in FIG. 5A, one
or more air cylinders, one or more inflatable bladders, and the
like. According to some other embodiments, the weight of substrate
125 may be sufficient to make use of a pressing means 9
unnecessary.
[0172] According to some embodiments of the invention, the carrier
1 may further include contacting means 11 for making electrical
contact with conductive substrates. The contacting means 11 may be
any suitable means for making electrical contact such as, but not
limited to, one or more springs, as shown in FIG. 5A, one or more
`fuzz buttons`, one or more `pogo pins`, and the like. Carrier 1
may further include damming means 13 (for example, an elastomeric
or conformable gasket). Furthermore, carrier 1 may include holes 15
for use in the eventual removal of substrate 25 and to serve as
reservoirs or risers for adhesive material 23 as shown in FIG. 5B,
and heating elements 17 preferably in close proximity to holes 15.
The carrier 1 may further include a carrier identification device
19 (such as, but not limited to, a bar code label or radio
frequency identification tag (RF ID tag). The carrier
identification device 19, in addition to or alternatively to
identifying the carrier or substrate, may encode a partial or
complete process sequence for a particular substrate, for example
indicating type of operations to perform and operations already
performed. For example, a sequence of operations may be readable
from an RF ID tag 19 along with an indication as to which
operations have been completed and any comments associated with
them. In other words, this RF ID tag may not only act as an
identification tag but also as a production traveler that
accompanies the structure as it is being formed and indicates the
state of the process and next operations to perform.
[0173] Referring to FIG. 5A, the carrier 1 is shown without
substrate 25. As shown in FIG. 5B, according to some embodiments of
the invention, meltable adhesive material 23 has been applied to
fill holes 15 before substrate 25 is loaded into the carrier.
Material 23 should be extremely rigid after solidification,
preventing any relative motion of substrate 25 and carrier body 2.
Material 23 should also be removable, for example, by melting or
chemical dissolution. Material 23 should withstand multiple cycles
of temperature cycling that substrate 25 may be exposed to while
being coated with photoresist, being immersed in electrodeposition
baths, and the like. Suitable meltable adhesive materials include,
but are not limited to, a mounting wax such as CrystalBond.TM. 509
made by Aremco Products of Valley Cottage, N.Y. and Staystik.TM.
571 made by Cookson Electronics of Alpharetta, Ga.
[0174] Heating elements 17 are preferably activated in order to
facilitate the material 23 filling operation. Removable film 21 has
been attached to the bottom of carrier 1. Film 21 may be, for
example, wafer dicing tape. The flow of material 23 is limited by
film 21 and by damming means 13, the latter preventing material 23
substantially from reaching contacting means 11 (which if material
23 is an insulator might impair electrical contact between
contacting means 11 and substrate 25). As depicted, damming means
13 also prevents material 23 from reaching and interfering with the
operation of pressing means 9.
[0175] Referring to FIG. 5C, substrate 25--onto which one or more
multi-layer structures is to be fabricated--has been placed into
carrier 1. In some embodiments carrier 1 includes a recess or
pocket (as shown) for receiving substrate 25 such that the top
surface 28 of substrate 25 may be made parallel and coplanar (i.e.,
flush) with the planar surface 3 of the carrier 1 (see FIG. 5F).
Substrate 25 may be covered with a thin removable film 27
preferably of uniform thickness (for example, wafer dicing tape).
In FIG. 5D, carrier 1 and substrate 25 have been inverted and
placed on planar surface 29 (for example, a granite surface plate)
with film 27 between substrate 25 and surface 29. Pressure is
applied to carrier 1 (if its own weight is insufficient) to press
substrate 25 via film 27 against pressing means 9 so that top
surface 28 of substrate 25 is forced to be coplanar with planar
surface 3 of carrier 1. Also as may be seen in FIG. 5D, film 21 has
been removed (this may be done after the step shown in FIG.
5B).
[0176] In FIG. 5E, material 23 has been melted by activation of
heating elements 17, causing material 23 to flow and fill gaps,
e.g. to fill gap 30 of FIG. 5D) between substrate 25 and carrier 1,
and causing substrate 25 to become rigidly adhered to carrier 1
when material 23 is allowed to cool and solidify. According to
other embodiments, heating elements 17 may be omitted and the
entire assembly may be placed in an oven, for example, in order to
melt material 23. In FIG. 5F, film 27 has been removed, leaving
material 23 substantially co-planar with surface 3.
[0177] Other embodiments of the invention may use other methods for
securing the substrate 25 to the carrier. For example, according to
some embodiments, a low melting point solder may be used to secure
substrate 25 to carrier 1. According to one embodiment, an
indium-based solder may be used. The solder may be applied, for
example, as a thin foil placed between the substrate 25 and the
carrier 1 and subsequently heated (for example, in an oven) to melt
the thin foil. Alternatively, the solder may be plated onto one or
more surfaces. In some embodiments, a layer of metal (for example,
gold) may be applied to the one or more surfaces to allow the
surfaces to be soldered. In the case of using a conductive bonding
material, it may be possible to remove damming means 13, as the
solder may be made to flow around pressing means 9 and prior to
pressing, the solder may be made flowable then pressing made to
occur such that pressing means and planar surface 9 bring carrier
surface 3 and substrate surface 28 flush, the solder, or other
conductive bonding material, may then be allowed to solidify
locking the substrate 25 and carrier 1 into fixed positions
relative to one another.
[0178] Referring to FIGS. 6A-6C, according to other embodiments,
carrier 1 may include apertures formed through the carrier body 2
that may be filled with, for example, a plated or melted metal such
that the substrate 25 may be mounted to the carrier body 2 and
secured due to the adhesion of the plated or melted metal to the
substrate 25 and/or due to mechanical interlocking after the plated
or melted metal has solidified.
[0179] A cross section of carrier body 2 is shown in FIG. 6A. As
shown, carrier body 2 has tapered apertures 26 in several places
extending from surface 3 of carrier body 2 through the carrier body
to surface 105. Also shown in FIG. 6A is substrate 25 before
attachment to carrier body 2. According to some embodiments of the
invention, substrate 25 may be either a metal substrate or may be
coated with metal on a least surface 101 such that metal may be
plated onto surface 101. In addition, according to some embodiments
where carrier body 2 is not metal, surfaces 107 may also be coated
with metal (e.g. by sputtering) such that metal may be plated onto
surfaces 107.
[0180] As shown in FIG. 6B, while surface 101 of substrate 25 is
held against carrier body 2, material 102 is plated or melted such
that it at least partially fills apertures 26 and makes contact
with surface 101 and surfaces 107. When material 102 is deposited
or solidifies it forms a good bond with surfaces 101 of substrate
25 and/or surfaces 107 of carrier body 2. According to some
embodiments, surfaces 101 and surfaces 107 may be roughened to
enhance adhesion.
[0181] In addition to the bonding of the material 102 to surface
101 and/or surfaces 107 as a result of plating or melting material
102 into apertures 26, some embodiments of the invention also
advantageously provide a strong mechanical bond as a result of the
geometrical shape of the apertures 26. FIG. 6C shows an example of
the mechanical bond. The downward and sideways pointing arrows
shown in FIG. 6C represent a force that potentially could cause
movement or separation of substrate 25 relative to carrier body 2.
The upward pointing arrows represent both the bond formed between
material 102 and surface 101 and the mechanical bond resulting from
the dovetail joint-like configuration formed by material 102 (the
tenon of the dovetail joint) and carrier body 2 (the mortise of the
dovetail joint). Due to the increased strength of the bond between
substrate 25 and carrier body 2 achieved by embodiments of the
invention, substrate 25 becomes more rigidly adhered to carrier
1.
[0182] A top view (looking toward surface 3) and a side
cross-section view of carrier body 2, according to some embodiments
of the invention, are shown in FIG. 7A. The top view is shown in
the upper portion of the FIG. 7A while the side view is shown in
the lower portion of FIG. 7A. In FIG. 7A, apertures 26 have a
conical shape similar to that shown in FIG. 6A-6B such that the
dovetail joint-like configuration described above may be achieved.
Also shown in FIG. 7A is a perspective view of one of apertures 26
(shown on the right side of the figure).
[0183] According to some embodiments of the invention, apertures 26
may have any suitable geometric shape that provides a strong
mechanical bond between carrier body 2 and substrate 25 after
material 102 is formed in the apertures. Some preferred embodiments
of the invention use a reentrant geometry, as shown in FIG. 7A.
FIG. 7B shows a top view (upper most portion of the figure),
looking toward surface 3, and a side section view of carrier body 2
(lower-most portion of the figure and a perspective view in the
right most portion of the figure. As an example of an additional
suitable reentrant geometric shape, FIG. 7B shows an aperture 26
having a v-shaped bar shape. As shown in the side view, the
dovetail joint-like configuration described above may be achieved
with the v-shaped bar.
[0184] According to yet other embodiments, the aperture may have
other suitable shapes. For example, the aperture may have a
diameter or width at surface 105 that is smaller than a diameter or
width of the aperture at surface 3, but wherein the shape of the
aperture is not the smoothly tapered shape shown in FIG. 7A. For
example, a large portion of the aperture may have substantially
vertical walls and a smaller portion that widen or narrow as they
approach surface 105 and/or surface 3, respectively.
[0185] If adhesion bonding of material 102 to surface 101 and/or
surfaces 107 is sufficient, then in some cases there is no need for
a mechanical bond such as that provided by the reentrant or other
geometrical shapes formed by material 102 and carrier body 2. Thus,
in some embodiments, apertures 26 may have, for example, vertical
walls. On the other hand, in embodiments where a mechanical bond is
provided, the adhesive bonding of the material 102 to surface 101
and/or surfaces 107 may be unnecessary. Still other embodiments may
use both types of bonding.
[0186] A build 103 of material layers may then be added to surface
28 of substrate 25 during the electrodeposition process, as shown
in FIG. 6B. After the electrodeposition process, substrate 25 may
be separated from carrier body 2 by removing material 102. Material
102 may be removed, for example, by dissolving, melting, chemically
etching or electro-chemically etching material 102 away. According
to some preferred embodiments of the invention, material 102 may be
nickel or copper. However, material 102 may also be a low
temperature metal such as indium, tin, or tin-lead. In still other
embodiments, material 102 may be a wax-like material, a thermal
polymer, or even a thermoset or photocurable polymer that may be
eventually be removed, e.g. by burning it out. According to some
embodiments, material 102 may be the same as the sacrificial
material used in the build, such that it may be removed (and the
carrier 1 released) during the process for removing the sacrificial
material. In some embodiments where the sacrificial material is
used as material 102, it may be undesirable to remove material 102
while the sacrificial material is removed. In that case, material
102 may be masked during, for example, an etching process for
removing the sacrificial material.
[0187] In order to avoid distortion of the bond between carrier 1
and substrate 25 due to mismatched coefficients of thermal
expansion (CTE), some embodiments of the invention may
substantially match the CTE of the materials used to form the
carrier 1 and the substrate 25. For example, if substrate 25 is
formed from a metal, carrier 1 may also be formed from a metal. If,
on the other hand, substrate 25 is formed from a ceramic or
polymer, carrier 1 may also be formed from a ceramic or polymer,
respectively. In some embodiments, the adhesive materials and/or
plating materials used to bond the carrier 1 to the substrate 25
may also be chosen to have a suitable CTE, i.e., if carrier 1 and
substrate 25 are formed from metal, the adhesive may also be a
metal.
[0188] In some embodiments, the adhesive may be chosen to allow for
a mismatch of the CTEs of carrier 1 and substrate 25, i.e., when
one of the carrier 1 or the substrate 25 expands more than the
other, the adhesive will maintain its bond between the two. In some
embodiments, the adhesive may be a conformable material or an
elastomeric material. The CTE of the material 102 may also be
matched to the CTE of the substrate and the materials used to form
the carrier 1, or may be chosen to allow for a mismatch of the CTEs
of carrier 1 and substrate 25 in embodiments wherein the carrier 1
has apertures as described above. If for example, the substrate and
carrier are made of metals, material 102 may take the form of a
glass (lower CTE) filled polymer (higher CTE) such that the CTE of
the combination more closely matches that of the metals
[0189] According to yet other embodiments of the invention,
substrate 25 may be made very thick. The increased thickness of
substrate 25 may provide enough stability such that a process flow
like that shown in FIGS. 4A-4I may be performed without the need
for a carrier, such as carrier 1. In addition, the increased
thickness of substrate 25 may make it less fragile. After a build
of layers has been completed on the substrate 25, backgrinding or
other machining processes (for example, lapping, milling,
electrical discharge machining, chemical milling, fly cutting) of
the substrate 25 may be performed to thin the substrate 25.
Thinning of substrate 25 may be performed prior to dicing into
individual die if desired.
[0190] Referring to FIG. 5G, if substrate 25 is sufficiently
conductive and of a suitable composition to allow for
electrodeposition of material used in making the desired
multi-layer structure--either throughout its bulk (as would be the
case with solid metal) or by virtue of a conductive coating on
surface 28 (e.g. a seed layer or seed layer and adhesion layer
combination) and preferably one other surface (for example, the
bottom surface directly opposite top surface 28 (in which case the
edges of substrate 25 may need to be coated to electrically connect
surface 28 with the bottom surface)--then electrical contact with
surface 28 may be made through contacting means 11 (or even
pressing means 9). As shown, contacting means 11 make contact with
substrate 25 on its bottom surface; however, contact through the
side of substrate 25 is another option, and contact with other
surfaces is also possible. In other cases, substrate 25 may be
covered on top surface 28 by one or more layers of material 31 (for
example, sputtered or evaporated gold in the range of 0.1-3.0
micrometers thickness on top of sputtered or evaporated titanium or
chromium in the range of 0.01-0.1 micrometers in thickness).
[0191] In FIG. 5G it is assumed that conductive material 31 is
required, and material 31 has been deposited so as to cover surface
28 and extend across material 23 and form an electrical connection
to carrier 1. Carrier 1 is here presumed to be composed of a
conductive material (for example, electroless nickel-plated cast
iron with low residual stress); if this is not the case, a
conductive insert may be provided at the top of carrier 1 onto
which material 31 can be deposited. By virtue of either contacting
means 11 and conductive substrate 25, or else material 31; surface
28 is now conductive and capable of receiving electrodeposited
material. In embodiments where conductive material 31 is added, the
substrate need not be conductive and contact means 11 need not
exist as electric connection is made directly by material 31 to the
carrier 1 and electrical connection between the carrier and an
external power supply may be made in any appropriate way. In
embodiments where electroplating solution is located only on the
upper surface of material 31, no shielding of other portions of the
carrier from electrodepositions may be necessary but when no such
limitation is placed on the electroplating solution, it may be
necessary to shield the rest of the carrier in some manner.
[0192] In FIG. 5H, a patternable mold material 33 has been applied
to material 31. The patternable mold material 33 is assumed to be a
dry film photoresist. However, some embodiments of the invention
may use other types of photoresist such as, but not limited to,
liquid or electrodepositable (electrophoretic) photoresists. In
FIG. 5H the patternable mold material 33 is shown being applied by
a lamination roller 34. However, other embodiments of the invention
may apply the patternable mold material 33 by other means such as,
but not limited to, vacuum laminating, roller coating, spraying,
spin coating, ink-jet printing, silk screening and the like.
[0193] According to some embodiments of the invention, different
patternable mold materials (for example, photoresists) may be
chosen for different layers based on their different properties.
For example, some photoresists may allow for thicker layers while
others may allow for the patterning of smaller features. Other
photoresists may have better chemical resistance to particular
plating or etching baths. Thus, some embodiments of the invention
may use a dry film photoresist on some layers and a liquid or
electrodeposited photoresist on other layers. Also, positive resist
may be used on some layers, while negative resist may be used on
other layers. A single layer may also use more than a single type
of resist for patterning of a deposit.
[0194] The choice of photoresists may be based on such additional
factors as wall geometries, different minimum feature capabilities
of the photoresist, whether a small positive feature or a small
negative feature is desired (for example, a small aperture or else
a narrow wall or small post). Thus, some embodiments of the
invention may analyze a geometry of a device or structure on a
layer by layer basis in order to determine the type of features
that are present on a particular layer. Based on the results of
that determination, a particular photoresist may be chosen to
pattern that layer. The geometry analysis may be performed, for
example, by a suitable processing device running a suitable
software program, or may be performed by hardware, firmware or a
combination thereof. For example, 3-D CAD software may be used to
analyze the geometry of a device by cross-sections. Based on this
analysis, one type of photoresist may be used for a cross-section
having one thickness, while another photoresist might be used for a
different cross-section having a different thickness. Similarly,
the software might analyze feature sizes on different layers of the
device and different photoresists may be chosen for different
layers based on the analysis.
[0195] Some embodiments of the invention may also modify
patternable mold material (e.g. dry film or liquid photoresist)
development parameters on a layer-by-layer basis based on, for
example, the wall geometries, different minimum feature
capabilities of the photoresist, whether a small positive feature
or a small negative feature is desired. Exemplary modifiable
development parameters include, for example, developer and rinse
droplet size, the pressures under which the developer and rinse are
applied, and the like.
[0196] In addition, after a patternable mold material development
and/or stripping process, residue of the patternable mold material
may be more likely to remain where particular geometries or feature
sizes are present. Thus, some embodiments of the invention may
determine on a layer by layer basis, for example, using software,
whether there is likely to be a residue of patternable mold
material remaining after development and/or stripping of the
patternable mold material based on particular geometries or feature
sizes. In this manner, removal of residue, or focused removal
operations, may be performed only on those layers or portions of a
layer where it is required. The residue of patternable mold
material may be removed, for example, by a plasma etch.
[0197] As discussed above, one method for applying a photoresist is
to use a dry film laminator incorporating lamination roller 34 and
secondary roller 38 shown in FIG. 5H. A schematic diagram of a
laminator used according to some embodiments of the invention, is
shown in FIG. 8. As shown, a roll of dry film resist 98 is located
around one roller 34 which is spaced from a second roller 38. As
shown, the upper roller 34 (adjacent to resist 98) would normally
be heated. Substrate 106 (e.g. a circular disk) is pushed between
the two rollers to apply the dry film resist. Because of a
non-uniform feeding effect that may occur due to the
non-rectangular shape of substrate 106 as it enters between the two
rollers, the resist applied to the substrate 106 may be wrinkled or
otherwise distorted.
[0198] Thus, some embodiments of the invention provide a carrying
template for holding the substrate 106 (or substrate 106 in a
carrier such as carrier 1) as it is passed through the hot roll
laminator 104. An exemplary embodiment of a template 109 for this
purpose is shown in FIG. 9A. Template 109 comprises a plate
including an aperture 110 passing entirely through the plate for
holding the substrate 106. Aperture 110 may be of a suitable size
to properly receive and hold substrate 106. In some embodiments,
the template thickness is sized such that the top surface of
substrate 106 will be substantially flush with the top surface of
the template 109 (i.e., either flush with the top surface or within
a small amount of being flush, for example, within one millimeter).
While secured in device 109, the lamination applied to the
substrate 106 will be substantially undistorted as it enters
between the rollers because the rectangular front edge of the
template 109 will be grabbed by the rollers rather than the wafer
itself.
[0199] FIG. 9B shows another embodiment of a carrying template 112
that may be used to hold substrate 106 during the lamination
process. Carrying template 112 differs from carrying template 109
shown in FIG. 9A in that aperture 115 does not pass entirely
through carrying template 112, but instead has a bottom as shown.
The depth of aperture 115 may be chosen such that the top surface
of substrate 106 will be substantially flush with the top surface
of the template 109.
[0200] According to embodiments wherein multiple layers are added
to the substrate during a process flow like that shown in FIGS.
4A-4I, it may be required to use multiple templates for the
lamination process. Each template may have a different thickness or
aperture depth corresponding to a new height of the substrate after
an additional layer or layers has been added. According to other
embodiments, the template may include shims or other height
adjustment members that are used for the initial layers. The shims
may be removed or interchanged as the height of the substrate
increases. According to embodiments wherein the top surface of
substrate 106 is lower by a small amount than the top surface of
the template 109 (for example, by one millimeter) template
thickness or aperture depth may not require adjustment each time a
new layer is added (i.e., a given thickness or depth may cover a
range of substrate thicknesses).
[0201] An exemplary embodiment using shims is shown in FIGS.
10A-10B. In FIG. 10A, template 112 holds substrate 106 before the
addition of any layers to the substrate. The substrate 106 sits on
a suitable number of shims 113 such that the top surface of the
substrate is substantially flush with the top surface of the
template 112. FIG. 10B shows substrate 106 after a build 114 of
layers has been added to the substrate. Shims 113 have been removed
since the new height of the substrate allows the top surface of the
substrate to be substantially flush with the top surface of the
template 112 without the shims.
[0202] According to further embodiments, a screw adjustment, spring
loader, or other suitable mechanism may be used in place of the
shims in order to keep the substrate 106 (or the top surface of
build 114) substantially flush with the top of the template 112 or
in another suitable position, for example, some distance above the
top surface of the template 112.
[0203] According to yet other embodiments of the invention, the
substrate may itself have a rectangular shape. In this case, a
template such as template 112 may not be required to avoid
wrinkling or other distortion of the resist applied to the
substrate.
[0204] When multiple layers are added to the substrate during a
process flow like that shown in FIGS. 4A-4I, as additional layers
are added to a substrate and laminated, the conditions of the
lamination process may be altered. As an example, as additional
metal layers are added to the substrate, a point may be reached
where the mass built on the substrate begins to pull excessive heat
away from the resist (by means of conduction and the increase in
thermal mass) and thereby results in poor adhesion of the resist to
the substrate or other problems.
[0205] Therefore, according to some embodiments of the invention,
the conditions of lamination (for example, feed rate, roller
temperature, pressure, and the like) may be altered during the
process of forming multi-layer structures (e.g. based on a
determination of the thermal mass and conductivity of build 114 or
more simply based on the total layer height added). One embodiment
of the invention provides a method for operating a lamination
system wherein the identity of a substrate about to enter the
system is determined (for example, using the carrier identification
device 19 discussed above). Then, a determination of thermal mass
and conductivity is determined for the identified substrate based
on, for example, determining the number of layers on the substrate,
the total thickness of the layers, percentages and types of metals
in the layers, and the like. Alternatively, in some embodiments, it
may be sufficient to determine simply the total current layer
height and to adjust process parameters accordingly.
[0206] The lamination parameters are then adjusted to achieve
optimal adhesion of the patternable mold material to the layer
being laminated based on the determined thermal mass and
conductivity. According to some embodiments of the invention, the
determination of thermal mass and conductivity and adjustment based
thereon may be performed manually or automatically, for example, by
a suitable processing device running a suitable software program,
or may be performed by hardware, firmware or a combination
thereof.
[0207] To enhance adhesion of photoresist to material 31 or to any
of the materials that may be present on a previous layer of a
multilayer structure built according to some embodiments of the
invention, microetches may be used. For example, microetchants
suitable for enhancing adhesion to copper include CE-100 Copper
Etchant (Transene Company Inc., Danvers, Mass.). Microetchants
suitable for enhancing adhesion to nickel include TFB Nickel
Etchant, Type 1 Nickel Etchant and TFG Nickel Etchant (Transene
Company Inc., Danvers, Mass.). Microetchants suitable for enhancing
adhesion to gold include GE-8148 Gold Etchant (Transene Company
Inc., Danvers, Mass.). Alternatively, mechanical roughening (e.g.,
application of abrasive such as pumice) may be used to enhance
adhesion. Alternatively, an adhesion promoter (e.g., HMDS
(hexamethyldisilazane) may be applied to the surface to be coated
with resist, in which case special treatments (e.g., plasma
etching) to remove traces of adhesion promoter after developing or
stripping and before deposition of structural or sacrificial
material may be required.
[0208] In some embodiments, structures will be formed using nickel
or a nickel alloy as a structural material and using copper as a
sacrificial material. It is known that some dry film photoresists
adhere better to copper than nickel. As adhesion is important to
successful layer patterning, in some embodiments it may be
desirable to enhance adhesion between a dry film, or other
photoresist, and the substrate or previously formed layer. Such
adhesion enhancement may occur in a variety of ways, for example
(1) by roughening the surface of the substrate or previous layer to
enhance mechanical bonding between the dry film, or other
photoresist, and the surface, and/or (2) by applying a material to
the substrate that adheres well to the materials of the previous
layer and which can also chemically bond with the photoresist. For
example, if the previous layer comprises regions of a first
material (e.g. copper) and a second material (e.g. nickel), a dry
film may chemically bond with first material upon pressing and/or
heating whereas it may only mechanically bond with the second
material. If a thin seed layer of the first material or of another
material that has similar adhesion properties may be applied to at
least the regions of the previous layer occupied by the second
material, then good adhesion between the photoresist and the entire
previous layer or substrate may be achieved.
[0209] Depending on how the seed layer is applied; depending on
whether it is acceptable for the seed layer material to exist
between layers of the structural material, between layers of the
sacrificial material, and/or between layers of different materials;
depending on the order of depositing the structural material and
the sacrificial material; and/or depending on the order of
deposition of the first material and the second material different
process flows may be defined which allow for successful fabrication
where good adhesion between photoresist and substrates and/or
previously formed layers may be obtained.
[0210] For example, one such embodiment may contain the following
steps or operations: (0) assume the sacrificial material is the
first material and is the material that is to be deposited first;
(1) apply a thin seed layer (e.g. less than 1 micron, more
preferably less than 0.5 microns, and even more preferably less
than 0.2 microns) of sacrificial material to the previously formed
layer; (2) apply and pattern the photoresist, (3) deposit the
sacrificial material to a height at least as great as the layer
thickness, which may for example be 2 microns or less, 5 microns or
less, 10 microns or less, and even 50 microns or more, (4) remove
the photoresist, (5) perform a flash etch to remove a thickness of
sacrificial material equal to or somewhat greater than the height
of the seed layer to exposure regions of structural material that
exist on the previous layer, and (6) selectively or blanket deposit
the structural material to a height at least as great as the layer
thickness, and (7) planarize the deposited material to complete
formation of the layer.
[0211] Another such embodiment might involve the following steps or
operations: (0) assume the structural material is the second
material and is the material that is to be deposited first; (1)
apply a thin seed layer of sacrificial material to the previously
formed layer; (2) apply and pattern the photoresist, (3) perform a
flash etch to remove exposed regions of the seed layer, (4) deposit
the structural material to a height of at least one layer
thickness, (5) remove the photoresist, and (6) selectively or
blanket deposit the sacrificial material to a height at least as
great as the layer thickness, and (7) planarize the deposited
material to complete formation of the layer. Other alternative
embodiments based on other build option selections are possible and
will be apparent to those of skill in the art upon reviewing the
teaching herein.
[0212] In some alternative embodiments, steps or operations (5) and
(4) (the seed layer removal operations) of the above two outlined
embodiments, respectively, may be eliminated if the depositions are
very thin to begin with, or they may be partially eliminated by not
necessarily trying to eliminate all exposed seed layer material. It
may not be necessary to completely remove all seed layer material
if it is thin enough or made to be thin enough as extremely limited
access to any sacrificial material located between successive
regions of structural material on adjacent layers may substantially
eliminate risk of etching resulting in delamination. Such
alternatives may also require that any sandwiched sacrificial
material (i.e. located between layers of structural material) not
have any other negative impact (e.g. reduction in strength of the
structure, reduction in conductivity, or the like) on the structure
as it is intended to be used.
[0213] According to some embodiments of the invention, multiple
layers of photoresist may be added in succession to the substrate
to obtain a thicker photoresist before any patterning of the
photoresist is performed. FIG. 11A-11E shows an embodiment of this
process. In FIG. 11A, a substrate 115 is provided. In FIG. 11B, a
first layer of photoresist is applied, for example by the
lamination roller 104 shown in FIG. 8A. This process is repeated
and a second layer of photoresist is applied, as shown in FIG. 11C.
This process is repeated again and a third layer of photoresist is
applied, as shown in FIG. 11D. After a final layer has been
applied, patterning of the thick photoresist may be performed, as
shown in FIG. 11E. In some alternative embodiments, exposure (i.e.
latent patterning) may occur after all layers of photoresist have
been accumulated or exposure may occur one or more times prior to
accumulating all layers of photoresist. In either alternative,
development of photoresist is preferably delayed until after all
layers of photoresist are formed.
[0214] Dry film resists may be used as the patternable mold
material, according to some embodiments of the invention. Dry film
resists typically come in layers having a thickness between 10 and
50 microns. A thinner resist may allow for smaller feature sizes.
Thus, according to some embodiments of the invention, after a
single layer of dry film resist is applied to the substrate, for
example by the lamination roller 104 shown in FIG. 8A but before
patterning the resist, the layer is thinned to a desired thickness.
Thinning of the dry film resist layer may be done in any suitable
manner, for example by plasma etching. Alternatively or
additionally, a suitable dilute chemical stripper may be used to
thin the dry film resist layer.
[0215] Alternatively, rollers or plates may be used to thin the dry
film resist layer by the application of pressure. It may desirable
to have the roller or plate heated. In addition, because of the
aqueous nature of the dry film resist layer, moisture may make the
film more flowable. Thus, it may also be desirable to wet the dry
film resist layer if a roller or plate is used. Also, the dry film
resist layer may be thinned by cutting with a tool, for example a
diamond fly cutter. Further, the dry film resist layer may be
thinned by abrading, for example by sandblasting or by lapping.
[0216] If a dry film resist is used, the supplied top cover sheet
(not shown) may be removed to improve resolution capability.
Exposure to oxygen may then however inhibit polymerization, in
which case the sheet may be removed just prior to exposure. Some
embodiments of the invention may replace the sheet with a thinner
oxygen barrier, or exposure may be conducted in an inert gas such
as nitrogen.
[0217] In some embodiments that use dry film or liquid based
resists, non-planarities in the surface of an applied film or cured
liquid resist may be removed by a planarization operation prior to
any exposure of the photoresist, if it is believed that the surface
irregularities may lead to irregularities in exposure of the
resist. If it is difficult to achieve a planar coating of resist as
a result of depressions or protrusions on a surface to which the
resist is applied, it is possible that two or more applications of
resist, (e.g. liquid resist) possibly with one or more intermediate
curing operations, will lead to more uniform, or planar, resist
surfaces.
[0218] Referring now to FIG. 5I, according to some embodiments of
the invention, material 33 has been removed (for example, by
trimming) if necessary so it does not cover up alignment target
pattern 35 on insert 5. Trimming may be done, for example, by a
mechanical knife or other suitable cutting tool. Alternatively,
trimming may be done by applying pressure to an area adjacent to
the area to be trimmed (i.e. to the area of targets) and then
tearing the material 33 away. Pressure may be applied, for example,
by a plate or tool having a sharp or serrated edge. In some
embodiments, the plate may contact material 33 only in areas
adjacent to the desired tear but not in other areas, to prevent
damage. According to other embodiments, the material 33 to be
trimmed may be isolated from the remainder, for example, by an
elastomeric seal, and chemically dissolved by stripping or
developing the material 33 to be trimmed.
[0219] According to other embodiments, trimming of material 33 may
be avoided in several ways. For example, in some embodiments the
roll of material 33 may be slit to a width such that it will not
cover alignment target pattern 35 when applied. Further, roller 34
may be sized such that its contact area is only as wide as the area
to be laminated. In this case, the roller does not apply heat and
pressure to the area of the carrier or substrate that includes the
alignment targets. According to other embodiments, a release film
may be used to cover the targets. The material 33 would then stick
to the release film rather than to alignment target pattern 35. The
release film may be, for example, mylar, and may be peeled away
after lamination of the material.
[0220] In other embodiments, it may not be required to trim
material 33 if vacuum applied between substrate and photomask is
used to temporarily draw the material 33 up against the photomask
surface to verify alignment. In this case, material 33 may become
flat against the mask and may not substantially distort or displace
the image of the target.
[0221] Patterns 35 and 36 may be protected by coating inserts with
a hard protective layer. Cover 7 has been removed to expose
patterns 35 and 36. Patterns 35 and 36 are each a diamond, cross,
circle, square, or other pattern suitable for precise optical
alignment, preferably using automated machine vision equipment.
According to some embodiments of the invention, patterns 35 and 36
may be formed on inserts 5, the latter being rigidly mounted to
carrier 1 (for example, as a press fit or with a suitable
adhesive), or else may be formed directly on carrier 1 (for
example, by engraving or etching).
[0222] Referring to FIGS. 5I-5J, carrier 1 is affixed to stage 40
such that photomask 42--consisting of substrate 37 (for example,
glass or quartz) and non-transmitting coating 39 that is patterned
to form clear regions 41 representing the cross-section of the
first layer of the desired structure (or its complement)--is above
patternable material 33. Photomask 42 is preferably arranged with
coating 39 in close proximity to material 33. Photomask 42 may be
coated with a non-adherent film such as Teflon.RTM., SYTOP.RTM.
(Asahi Glass Co., Ltd.) or parylene to reduce the risk of material
33 adhering to it, especially if material 33 is dry film resist
from which the cover sheet has been removed. To reduce diffraction
and improve resolution, some embodiments of the invention provide
an index matching liquid (for example, water, not shown) in the gap
between photomask 42 and material 33 to provide a refractive index
more closely matching that of photomask substrate 37 and/or
patternable material 33.
[0223] Referring to FIG. 5J, according to some embodiments of the
invention, the coating portion of mask 42 and the surface of
material 31 are adjusted to be highly parallel. Since material 33
is relatively uniform in thickness, this can be accomplished by
temporarily allowing pitch and roll motion of carrier 1 on stage
40, raising carrier on stage 40 until coating 39 and material 33
are in contact, then preventing further pitch and roll motion and
lowering carrier 1 again to produce a gap which will allow for
relative alignment. Parallelism is required to obtain the best
resolution, to produce sidewalls that are substantially orthogonal
to the surface of substrate 25, and other distortions. According to
some embodiments of the invention, various methods of aligned
patterning may be used, including, but not limited to, contact
alignment, proximity alignment, stepper alignment, scanner
alignment, or projection alignment.
[0224] As shown in FIG. 5J, photomask 42 is provided with alignment
targets such as 43 and 45. For purposes of illustration, alignment
target 43 is shown as necessarily having a clear field (i.e., free
of coating 39 except in a small area), while target 45 is shown
optionally as having a dark field (i.e., having coating 39
everywhere except in a small region); however, a clear field target
is also suitable for target 45. Initially targets 43 and 35, and
targets 45 and 36, respectively, are not aligned, as shown in FIG.
5J. Photomask and substrate targets are designed so that both
remain visible when the photomask and target are well-aligned.
[0225] FIG. 5J illustrates two alternative embodiments for imaging
the alignment targets on both carrier 1 and photomask 42. The first
embodiment is illustrated by the imaging system 47 shown on the
left side of the figures. The second embodiment is illustrated by
the two imaging systems 51 and 53 shown on the right side of the
figures. However, it should be understood that during the following
discussion of the first and second embodiments, it is assumed that
both the left and the right side of the figures include the imaging
systems of the embodiment under discussion.
[0226] Both embodiments allow for alignment of each successive
photomask pattern to carrier 1 (i.e., to substrate 25) rather than
to the previously-deposited layer, to advantageously avoid the
accumulation of errors that can lead to poor registration of
layers. In the first approach, imaging system 49 (here assumed to
be an electronic camera with microscope optics, though direct
observation is also possible with the second embodiment) can be
moved vertically on precision stage 50, preferably having excellent
straightness of travel with minimal roll, pitch, and yaw or
translation other than axial. Stage 50 is preferably aligned so
that its axis of travel is both extremely parallel to the optical
axis of system 49, and extremely perpendicular to the photomask
bottom surface (i.e., coating 39).
[0227] In the position shown, system 49 can focus on target 35 in
its current position. As layers are added and carrier 1 descends
gradually, system 49 can be lowered on stage 50 in order to remain
focused on target 35 even if the amount of motion of carrier 1
exceeds the depth of focus of the optics of system 49 (for example,
several microns or tens of microns). System 49 can also be raised
(shown as phantom lines 47) to focus on photomask target 43. It
should be noted that the directions indicated (raised, lowered,
etc.) refer to the figures and that other embodiments are possible
in which the apparatus moves in other directions than those shown.
It should also be noted that although in the embodiment shown the
photomask is stationary while the substrate moves, other
embodiments may keep the substrate stationary, while the photomask
moves. In this case, the optics of system 49 looking at photomask
may move with the photomask.
[0228] According to the second embodiment, two imaging systems 51
and 53 are used to independently (and if desired, simultaneously)
focus on targets 45 and 36, respectively. Thus, there are two
different focal points. If desired, the optical axes of systems 51
and 53 can be made coaxial (not shown) through the use of, for
example, a beamsplitter or similar device. System 53 can be lowered
on stage 52 (similar to stage 50 in terms of precision and
alignment, but optionally with shorter travel) in order to remain
focused on target 36. System 51 may remain fixed and focused on
target 45. Both embodiments are shown by way of illustration.
However, normally one embodiment or the other may be used for
alignment of all targets that are used (the minimum number of
targets needed to obtain alignment in X, Y, and theta (rotation) is
two).
[0229] Assuming that the first embodiment is being used and that
there are two targets each on both photomask 42 and carrier 1, then
in FIG. 5J the focused images of targets 43 (now assumed to be two
distinct targets) are formed by imaging systems 49 (now assumed to
be two distinct imaging systems) when raised into focus (as shown
by phantom lines 47) using stage 50. When systems 49 are at a lower
position of stage 50, the focused images of targets 35 are formed
by them.
[0230] Images are recorded of targets 43 and 35 and compared (for
example, by superimposing them) by an operator or by a machine
vision system to determine the degree of misalignment, and carrier
1 is repositioned in X, Y, and theta to achieve alignment, as is
shown in FIG. 5K. Note that target 43 must be designed so as to
allow target 35 to be viewed through it.
[0231] Assuming that the second embodiment is being used and that
there are two targets each on both photomask 42 and carrier 1, then
in FIG. 5J the focused images of targets 45 (now assumed to be two
distinct targets) are formed by imaging systems 51 (now assumed to
be two distinct systems). When imaging systems 53 (now assumed to
be two distinct systems, for a total of four imaging systems, i.e.
two on the left and two on the right of the FIGS.) are at a lower
position of stage 52, the focused images of targets 36 (now assumed
to be two distinct targets) are formed by them.
[0232] Images are recorded of targets 45 and 36 and compared (for
example, by superimposing them, which can be done electronically
even though the targets are not physically overlapping) by an
operator or by a machine vision system to determine the degree of
misalignment, and carrier 1 is repositioned in X, Y, and theta to
achieve alignment, as is shown in FIG. 5K. Note that photomask 42
requires a clear region 54 through which to view target 36, but
target 45, which is not coincident with region 54, can have any
suitable geometry and be either clear or dark field.
[0233] According to some embodiments of the invention, as layers
are added to substrate 25, the focus of the imaging systems may be
adjusted automatically by lowering the imaging system by an amount
that is based on data regarding the thickness of the layer that has
been added. In addition, the data regarding the thickness of the
layer may be used to verify that an expected thickness of a layer
that has been added actually has that thickness. For example, when
the imaging system is lowered a specified amount based on the
thickness data, the imaging system should be focused properly. If
the imaging system is not focused properly, this may indicate that
the layer does not have the expected thickness. Such a
determination may require that a patternable mold material layer
thickness is consistent. The automatic adjustment and determination
may be performed, for example, by a suitable processing device
running a suitable software program, or may be performed by
hardware, firmware or a combination thereof.
[0234] According to other embodiments, an imaging system including
a camera using a large depth of focus, such as a long-working
distance lens or a telecentric lens may be used in place of the
cameras discussed above. In this case, movement of the imaging
system may be avoided, as the large depth of focus of the lens may
be sufficient to cover a large gap between targets 43 or 45 and
targets 35 or 36.
[0235] According to another embodiment of the invention, backside
alignment may be performed by placing targets on the back side of
carrier 1. Referring to FIGS. 28A-28B, photomask 144 is provided
with alignment targets 145 and 146. Carrier 1 is provided with
alignment targets 147 and 148, which are formed on the backside of
the carrier 1 (for example, as a press fit), or else may be formed
directly on carrier 1 (for example, by engraving or etching). As
shown in FIG. 28A, back-side imaging system 149 includes two
cameras which face upward towards the photomask 144.
[0236] Initially, imaging system 149 stores the images of alignment
targets 145 and 146 on photomask 144. Then, as shown in FIG. 28B,
carrier 1 is placed between imaging system 149 and photomask 144.
The live images of the alignment targets 147 and 148 are aligned
with the previously stored images of alignment targets 145 and
146.
[0237] Backside target alignment as described above is advantageous
for various reasons. For example, because the targets 147 and 148
are isolated from the patternable mold material being applied, they
cannot be obscured by the patternable mold material. Also, the
targets 147 and 148 cannot be damaged by lapping or other abrading
operations performed on the opposite side of carrier 1 or by
plating baths to which the targets may be exposed. In addition,
when using back side alignment, as more layers are added to carrier
1, there is no limitation to the number of layers that may be added
to the substrate because the photomask will not come in contact
with the imaging system, as it might in the front side alignment
system previously described.
[0238] The embodiments described above for performing alignment in
relation to alignment targets located on the carrier are equally
applicable to embodiments of the invention having alignment targets
located on the substrate, as will be discussed below.
[0239] Whatever embodiment is used for alignment, once photomask 42
and carrier 1 are in alignment, carrier 1 is preferably raised on
stage 40 so that coating 39 is in contact with material 33, as
shown in FIG. 5K, prior to exposing material 33. Vacuum may be
applied between photomask 42 and carrier 1 to increase contact
pressure, and carrier 1 may be provided with specialized means of
obtaining a vacuum seal against photomask 42, such as an
elastomeric seal. Alternatively, a seal entirely made from
elastomer or at least whose upper surface is elastomeric may be
provided on stage 40, surrounding carrier 1. Similarly, contact
between coating 39 and the surface of material 33 can be improved
by applying gas pressure to force the two together.
[0240] In FIG. 5L, material 33 is being exposed to light (for
example, ultraviolet) that is preferably highly-collimated and
which passes through photomask 42 in clear regions 41. In FIG. 5M,
photomask 42 has been removed and material 33 has been developed to
yield a pattern corresponding to that of coating 39, with regions
57 no longer covering material 31. Note that in the example
illustrated, material 33 behaves as a negative-working resist,
becoming insoluble to the developer in those regions exposed to
light. According to other embodiments, a material with the opposite
(positive-working) characteristics may also be used.
[0241] Development, in the case of a dry film photoresist, may be
performed by, for example, spraying an alkaline aqueous developer
at coating 33 in a controlled and uniform fashion and at the
correct temperature, followed by rinsing. To develop dry film
photoresist so as to achieve good yield on small features and as
uniform development as possible, a closely-spaced array of
direct-fan or atomizing nozzles (for example, air-atomizing nozzles
behaving like an airbrush) with a narrow spray angle (for example,
15 degrees) may be used for both developing and rinsing. These
nozzles may be arranged in several closely-spaced staggered rows if
they cannot be closely enough spaced in a single row. Some overlap
between the nozzles may be provided to improve uniformity. If
nozzles with a fan-type spray pattern are used, the major axis of
the fan may be rotated by a small angle (for example, 15 degrees)
from the normal to the direction of travel of the resist to
minimize interference and turbulence of one nozzle with its
neighbor. The use of a narrow spray angle and close spacing of
nozzles provides an angle of incidence of the developer or rinsing
solution that is as uniformly orthogonal as possible to the resist
surface. This is in contrast to developing and rinsing equipment
commonly used in the fabrication of printed circuit boards, in
which a few, widely-spaced nozzles with large spray angles (for
example, 45 degrees or more) are common. Also, in contrast to
normal processing wherein resist is moved slowly and
unidirectionally with respect to the nozzles, some embodiments of
the invention may move resist bidirectionally and quickly with
respect to the array of nozzles so as to improve uniformity of
processing and yield, minimizing the processing that occurs with
pooled (vs. ejected) liquid. If all of coating 33 is not removed in
regions 57 (for example, a thin residue remains), this may be
removed by methods such as plasma etching (for example, in an
oxygen plasma), mechanical abrasion, and the like, such that
material may be electrodeposited onto material 31 and excellent
adhesion obtained.
[0242] In FIG. 5N, optional insulating material 59 has been applied
over the edge of material 31 to prevent electrodeposited material
from being deposited near the edge of material 31. Preferably
material 59 is easily removable (for example, by melting or
chemical dissolution). In FIG. 5O, substrate 25 has been immersed
in an electrodeposition tank. Conventionally, the substrate itself
may seal against the electrodeposition tank. However, some
embodiments of the invention, as shown in FIG. 5O, allow carrier 1
to seal against tank 62. Gasket 61 makes contact with material 31
or, as shown, with material 59, forming a seal which prevents
deposition in the vicinity of insert 5 or on any other portion of
carrier 1. As shown, the carrier is located on the floor of the
electrodeposition tank; however, the carrier may also be located in
the ceiling or wall of the tank, or in a fixture that is placed
into the tank. According to some embodiments of the invention, the
plating bath in the electrodeposition tank may include a filler
material along with a plating material. The filler material may
accelerate the deposition rate of a plating material during the
plating process. For example, when the plating material is copper,
the filler material may be copper particles. In addition to metal
particles, hollow or solid polymer spheres, ceramic particles, and
other materials which displace volume and can be co-deposited with
plating material so as to increase deposition rate may be used.
Such particles may also be incorporated into an anode used during
the plating process.
[0243] According to some embodiments of the invention wherein an
adhered patterned material is used as the patternable mold
material, in order to improve uniformity of deposition rate counter
electrode 64 may be located at a closer proximity to the surface of
the mold material in the bath 60 than is shown in FIG. 5O, in some
embodiments being in contact or near-contact with the mold
material.
[0244] Tank 62 is filled with electrodeposition bath 60 and counter
electrode 64 is placed inside bath 60. Current is applied through
bath 60 using power supply 66. As shown, supply 66 provides a
direct current of a specific polarity which may be continuous or
pulsed. However, if the material to be deposited requires a cathode
counter electrode the polarity would be reversed. Also, some
embodiments of the invention may use a supply of `pulse-reverse`
current in which the current changes polarity periodically. By the
application of current from supply 66, deposit 63 of a first
material is created in regions 57.
[0245] In FIG. 5P, the remaining regions of material 33 are
removed, leaving a patterned deposit of material 63 with blank
regions 76. Such `stripping`, in the case of a dry film
photoresist, may be performed by spraying an appropriate alkaline
aqueous `stripper` at coating 33 in a controlled and uniform
fashion and at the correct temperature. If all of coating 33 is not
removed by the stripper (for example, a thin residue remains in
regions 76), this may be removed by methods such as plasma etching
(for example, in an oxygen plasma), mechanical abrasion, and the
like, such that material may be electrodeposited in regions 76 of
material 31 and excellent adhesion obtained.
[0246] In FIG. 5Q, substrate 25 has been immersed in an
electrodeposition tank. As shown, carrier 1 forms the floor of tank
68. Gasket 74 makes contact with material 31 or, as shown, with
material 59, advantageously forming a seal which prevents
deposition in the vicinity of insert 5 or on any other portion of
carrier 1. Tank 68 is filled with electrodeposition bath 72 and
counter electrode 70 is placed inside bath 72. Current is applied
through bath 72 using power supply 78. As shown, supply 78 provides
a direct current of a specific polarity which may be continuous or
pulsed. However, if the material to be deposited requires a cathode
counter electrode the polarity would be reversed. Also, a supply of
`pulse-reverse` current may also be used in which the current
changes polarity periodically. By the application of current from
supply 78, deposit of a second material 65 is created in regions
over material 63, contacting material 31 in regions 76.
[0247] According to some embodiments of the invention, one of the
first and second materials is a structural material, while the
other is a sacrificial material. The patternable mold material used
(for example, photoresist or solder mask) may be one that is
capable of achieving only small positive features (for example,
walls or posts). Alternatively, the patternable mold material may
be one that is capable of achieving only small negative features
(for example, holes or slots). Some embodiments of the invention
may select the order in which the sacrificial and structural
materials are deposited for a particular layer having a particular
patternable mold material deposited thereon, based on
characteristics of features that are to be patterned on the layer
and whether the particular patternable mold material produces
smaller positive or negative features with better yield or quality
(if both are not produced equally). For example, the order of
deposition may be selected based on whether small negative or small
positive features of structural material are to be patterned on the
layer. Referring to FIG. 12A, as an example of a small positive
feature, a small narrow wall of metal (for example nickel) is shown
after patterning. Referring to FIG. 12B, as an example of a small
negative feature, a small narrow aperture surrounded by a metal
(for example nickel) is shown after patterning.
[0248] Furthermore, the order of deposition may be selected based
on an aspect ratio of a feature or features. As an example, as
shown in FIG. 13, sacrificial material 118 is deposited on
substrate 108 in a pattern. Structural material 119 is blanket
deposited over sacrificial material 118 and into the aperture as
shown. If the aspect ratio of the aperture is too high, there may
be a void, i.e., structural material 119 may not penetrate to the
bottom of the aperture due to deposition on the sidewalls of
material 118 competing with deposition onto substrate 108. In such
a case, it would be desirable to first deposit the structural
material 119 rather than the sacrificial material 118, since the
first deposition would be within an insulating material (for
example, photoresist or solder mask).
[0249] As another example, the order of deposition may be
determined on a layer by layer basis based on a desired grain
structure for a structural material. The grain structure of the
structural material may vary based on whether the structural
material is deposited before or after the sacrificial material is
deposited. If the structural material is deposited into an aperture
wherein the walls of the aperture are patternable mold material and
thus non-conductive, a particular grain structure will occur
wherein the grains grow from the bottom of the aperture in an
upward direction. However, if the structural material is deposited
into an aperture wherein the walls of the aperture are a conductive
material that was deposited first (for example, the sacrificial
material), a different grain structure will occur wherein the
grains grow laterally from the walls of the aperture as well as
from the bottom of the aperture in an upward direction. Either
grain structure may be desirable for particular applications.
[0250] As an example of a process for patterning a small positive
feature of structural material--the small narrow wall shown in FIG.
12A--using a patternable mold material that produces better or
higher-yielding positive features, some embodiments of the
invention may, for a particular patternable mold material, deposit
a sacrificial material first and then deposit a structural
material, as illustrated in FIGS. 14A-14H. FIGS. 14A-14H show an
embodiment of a process for forming the narrow wall shown in FIG.
12A. In FIG. 14A, a substrate 108 is shown, onto which patternable
mold material 117 (for example, photoresist or solder mask) has
been deposited as shown in FIG. 14B. In FIG. 14C, material 117 has
been patterned (for example, if a photoresist, by use of a
photomask, developing, etc., by laser direct imaging, a pattern
generator and the like or, a combination of these methods) to
produce a small wall of material 117. In FIG. 14D, sacrificial
material 118 (for example, a metal such as copper) has been
deposited around the small wall of material 117 (for example, by
electrodeposition).
[0251] In FIG. 14E, material 117 has been removed (for example, by
use of a chemical stripper) to expose regions of the substrate 108
which are not covered with sacrificial material 118, leaving an
aperture having the desired pattern. In FIG. 14F, structural
material 119 (for example, a metal such as nickel) has been
deposited over the entire substrate 108 and into the aperture. In
FIG. 14G, the layer has been planarized to a sufficient depth to
remove all of structural material 119 overlying sacrificial
material 118, and also to establish a layer of the desired
thickness, flatness, and surface finish. The sacrificial material
118 is then ultimately removed, as shown in FIG. 14H, leaving the
desired narrow wall of structural material 119.
[0252] As an example of a process for patterning a small negative
feature of structural material (for example, the small narrow
aperture shown in FIG. 12B) using a patternable mold material that
produces better or higher-yielding positive features, some
embodiments of the invention may, for a particular patternable mold
material, deposit a structural material first and then deposit a
sacrificial material, as illustrated in FIGS. 15A-15E. FIGS.
15A-15E show an embodiment of a process for forming the narrow
aperture shown in FIG. 12B. In FIG. 15A, a substrate 108 is shown,
onto which patternable mold material 117 (for example, photoresist
or solder mask) has been deposited as shown in FIG. 15B.
[0253] In FIG. 15C, material 117 has been patterned (for example,
if a photoresist, by use of a photomask, developing, etc., by laser
direct imaging, a pattern generator and the like or, a combination
of these methods) to produce a small wall of material 117. In FIG.
15D, structural material 119 (for example, a metal such as nickel)
has been deposited around the small wall of material 117 (for
example, by electrodeposition). The photoresist is then removed, as
shown in FIG. 15E, leaving an aperture in the nickel. Sacrificial
material (for example, a metal such as copper) (not shown) may then
be blanket deposited (for example, by electrodeposition) over the
substrate to form other structures if necessary.
[0254] The determination of whether the structural or sacrificial
material is deposited first may be performed, for example, by a
suitable algorithm that analyzes cross sections of each layer and
makes the determination. The determination may be made based on
various factors. For example, some embodiments of the algorithm may
determine whether a predefined minimum feature size for positive or
negative features exists (for example, 10 or 20 microns) on a layer
being analyzed. Other embodiments of the algorithm may determine
whether a predefined number of positive or negative features on a
layer have a predetermined minimum feature size (for example, 10 or
20 microns). Yet other embodiments of the algorithm may assess the
importance of having accurate features on a particular layer.
Further embodiments of the algorithm may determine the aspect
ratios of features on an analyzed layer. The algorithm may be
performed by software, hardware, firmware or a combination
thereof.
[0255] A flowchart of an exemplary embodiment of an algorithm for
determining priority of deposition is shown in FIG. 16, assuming in
this case that on the layer being considered one is using a
patternable mold material that produces better or higher-yielding
positive features. At S1601, the layer of interest is analyzed. At
S1602, it is determined whether the layer has a feature with the
predefined minimum feature size. If there is not such a feature,
then no determination of priority of deposition of the sacrificial
and structural materials is made (S1603). If there is such a
feature, then at S1604 it is determined whether the feature is a
positive feature or a negative feature in the structural material
for that layer. If the feature is negative, then at S1605 the
structural material is deposited first. If the feature is positive,
then at S1606 the sacrificial material is deposited first.
[0256] The dimensions of the actual negative and positive features
(for example those shown in FIGS. 12A-12B) may not be the same as
the nominal, i.e., specified dimensions, selected using, for
example, computer aided design software. As an example, the nominal
width of a positive feature may be designed to be 20 microns, but
the actual feature may have a width of 18 microns, while an actual
negative feature may have an width of 22 microns, or vice versa.
The deviation or offset of the actual dimension from the nominal
dimension may not be symmetric in relation to the nominal
dimension. In other words, an actual negative feature having a
nominal width of 20 microns may have an actual width of 23 microns,
while an actual positive feature having a nominal width of 20
microns may have an actual width of 18 microns.
[0257] Some embodiments of the invention may determine in advance
what the dimension offset will be and may pre-scale edges of a
feature, for example using computer aided design software, in order
to compensate for any anticipated offsets. Photomasks may thus be
created wherein the patterns for patterning positive and negative
features include asymmetrical offsets.
[0258] Referring now to FIG. 5R, according to some embodiments of
the invention, carrier 1 is placed in planarization fixture 67.
Fixture 67 consists of ring 80 with hard stops 82, sliding stages
69, and support 71. Stops 82 are co-planar and formed from a
material (for example, polycrystalline diamond, silicon carbide,
cubic boron nitride, or aluminum oxide) that wears slowly on plate
73. As shown, surface 3 of carrier 1 mates with support 71. The
mating surface of support 71 is adjusted to be extremely parallel
with the bottom surface of stops 82, such that as stages 69
descends, materials 63 and 65 will become planarized such that
their surface will be very parallel to surface 3. Stages 69 are
distributed on the inside of fixture 67 preferably at uniform
intervals (e.g., 3 stages 120 degrees apart, 4 stages 90 degrees
apart). Alternatively, it is possible to make the surface of
carrier 1 that is opposite surface 3 (i.e., the backside of the
carrier) highly parallel to surface 3, and provide in fixture 67 a
support analogous to support 71 which mates with the backside of
carrier 1. Stages 69 may also be replaced by a single stage or
linear bearing above carrier 1 and mounted to its backside.
[0259] The mating surface of support 71 or its analog may be
aligned to be parallel with the bottom of stops 82 by various
methods, including the use of an autocollimator. This alignment may
also be performed once carrier 1 is held in fixture 67, a more
direct and probably more reliable method for achieving the desired
parallelism between surface 3 and the bottom of stops 82. In this
case, a region of a surface of carrier 1 (for example, the rear
surface opposite surface 3) may be given optical smoothness and
flatness, as well as a high degree of parallelism to surface 3, to
allow alignment using an autocollimator calibrated to establish
perpendicularity to the plane of stops 82.
[0260] With carrier 1 in fixture 67, materials 63 and 65 are
planarized by the use of an abrasive (for example, diamond,
aluminum oxide) applied to plate 73, which may be, for example, a
lapping plate made of materials such as copper, tin-antimony, cast
iron, and copper-resin composite. Alternatively, plate 73 may be
composed of an abrasive material and planarization performed by the
application of an appropriate lubricant. The planarization process
is stopped before materials 63 and 65 are reduced to their final
desired thickness.
[0261] As shown in FIG. 5S, according to some embodiments of the
invention, measurement sensors 75 are used to measure the thickness
of materials 63 and 65 (hereinafter called `the layer`). Such
sensors may be, for example, dial indicators with high resolutions,
LVDT (linear variable differential transformer)-based distance
gauges, and the like. Alternatively, non-contact sensors based on
light, eddy currents, capacitance, and so forth may be used.
Measurements of layer thickness are made by comparing the readings
of sensors 75 which measure the position of surface 3 with that of
sensors 84 which measure the position of the current as-planarized
surface, with both sensors preferably connected to a common
support.
[0262] Alternatively, if mechanical contact is used, either sensors
75 or 84 (but not both) may be replaced by a fixed-length ball or
other probe tip which is mechanically connected to the sensor,
reducing the total length of material between sensor and ball so as
to minimize variation due to temperature fluctuations and
mechanical deflection. Additional sensors similar to sensors 75 and
84 may be provided to determine uniformity of planarization (for
example, to determine whether the surface is flat is may be
desirable to place multiple sensors at various radii from the
center of substrate 25).
[0263] After sensing of layer thickness is performed, if additional
planarization is required to achieve the desired thickness or
flatness of the layer, it is performed as shown in FIG. 5R, and
additional sensing may be done to verify the result as shown in
FIG. 5S, possibly in an iterative fashion. In FIG. 5T, a layer
having a final desired thickness and flatness has been produced,
with surface 77 serving as substrate for subsequent layer
depositions. After the layer is planarized, a small region 79 of
material 65 may remain on the periphery of the deposited area. This
completes the formation of a single layer of a multi-layer
structure, according to some embodiments of the invention.
[0264] Formation of a second layer, according to some embodiments
of the invention, begins with a process of patterning a mold
material, analogous to that already described in FIGS. 5H-5M, but
typically using a different photomask pattern representing the
second cross-section of the multi-layer structure, which in general
is different from that used to pattern the first layer. Different
mold material may also be used.
[0265] In FIG. 5U, a patternable mold material 83 (here assumed to
be a liquid photoresist, but it may be, for example, a dry film
photoresist or an electrodeposited photoresist as well) has been
applied to layer surface 77. In some embodiments the resist is
applied on top of an antireflection coating 81 to avoid distortions
that may be encountered when an area where a feature is to be
patterned overlies two or more materials on a previous layer. The
problem results from the fact that the two or more underlying
materials may each have a different reflectivity and/or may each
have a different surface finish. As a result, the patternable mold
material overlying the materials in which the feature is patterned
may have varying amounts of exposure due to the varying reflection
of light from the underlying materials. This may result in a
distorted feature. The use of the antireflection coating 81 may
reduce such distortion by allowing for a more uniform exposure of
the patternable mold material.
[0266] If a liquid or electrodeposited photoresist is used, a
baking step may be required to dry the liquid photoresist or to
consolidate particles in the case of an electrodeposited
photoresist. If a carrier is used or if the substrate is thick, a
hot plate may be insufficient to perform this baking step. Thus,
some embodiments of the invention bake the photoresist using, for
example, an oven or infrared or microwave radiation. Whether a hot
plate, oven or radiation method is used to bake the photoresist, it
may be cooled by placing it on a cool plate, in a refrigerated
chamber, or in a flowing stream of air. Such methods may also be
used to cool dry film photoresist and laminated substrates after
lamination.
[0267] Material 83 may be applied by spinning carrier 1 (as assumed
here) or by other methods, resulting in an excess thickness 86
(i.e., an edge bead). In FIG. 5V excess material thickness 86 has
been removed, for example, by chemical dissolution, typically along
with some underlying material 83 and material 83 is soft-baked if
necessary or otherwise processed to prepare it for exposure. Cover
7 has also been removed to expose patterns 35 and 36.
[0268] In FIG. 5W, carrier is affixed to stage 40 such that
photomask 85 (consisting of substrate 86 and non-transmitting
coating 87) is above material 83. Photomask 85 is preferably
arranged with coating 87 in close proximity to material 83.
Photomask 85 may be coated with a non-adherent film to avoid
material 83 from adhering to it. To reduce diffraction and improve
resolution, a liquid may be provided in the gap between photomask
85 and material 83 to more closely match refractive index. Coating
87 and the surface of material 31 are adjusted to be highly
parallel, as before.
[0269] In FIG. 5X, photomask 85 and carrier 1 have been brought
into alignment as before with photomask 42 and carrier 1. Carrier 1
is also raised on stage 40 so that coating 87 is in contact with
material 83 prior to exposing material 83.
[0270] In FIG. 5Y, material 83 is being exposed to light (for
example, ultraviolet) that is preferably highly-collimated and
which passes through photomask 85 as before. In FIG. 5Z, photomask
85 has been removed and material 83 has been developed to yield a
pattern corresponding to that of coating 87 as before. Note that in
the example illustrated, material 83 behaves as a negative-working
resist, becoming insoluble to the developer in those regions
exposed to light; a material with the opposite (positive-working)
characteristics may also be used.
[0271] If all of material 83 is not removed in regions 90 (for
example, a thin residue remains), this may be removed by methods
such as plasma etching (for example, in an oxygen plasma),
mechanical abrasion, etc. such that material 89 may be
electrodeposited onto the previous layer (comprising materials 63
and 65) and excellent adhesion obtained, as shown in FIG. 5AA.
After complete removal of material 83 as before, material 91 is
deposited in its place, as before. In FIG. 5AA, planarization of
material 89 and 91 has been performed, and a third layer,
comprising materials 92 and 94 has been fabricated as before.
[0272] FIGS. 17A-17H illustrate a method for achieving both small
positive and negative features in the same layer when the
patternable mold material (for example, photoresist or solder mask)
cannot produce small features of both types equally well at least
according to some embodiments of the invention. In the example
illustrated, it is assumed that positive features in the mold
material are more easily produced. In FIG. 17A, patternable mold
material 117 is patterned (for example, if a photoresist, by use of
a photomask, developing, etc., by laser direct imaging, a pattern
generator and the like or, a combination of these methods) and
first material 120 (for example, copper) is deposited (for example,
by electrodeposition). In FIG. 17B, patternable mold material 117
is removed. In FIG. 17C, patternable mold material 117 is deposited
over first material 120. In FIG. 17D, patternable mold material 117
is patterned and it is assumed that the remaining region of mold
material 117 as shown in FIG. 17D is narrower than a negative
feature that could have been formed for example in obtaining the
state of the process shown in FIG. 17A.
[0273] In FIG. 17E, a second material 121 (for example, nickel) is
deposited (for example, by electrodeposition). In FIG. 17F,
patternable mold material 117 is removed. In FIG. 17G, first
material 120 is blanket deposited over second material 121. In FIG.
17H, the layer has been planarized to a sufficient depth to
establish a layer of the desired thickness, flatness, and surface
finish. It will be understood by one skilled in the art that a
similar process for achieving both small positive and negative
features in the same layer as that described above in reference to
FIGS. 17A-17H may be performed when a patternable mold material
that more easily produces small features that are negative is used
on a layer.
[0274] It may desirable to deposit more than two materials on a
single layer. FIGS. 18A-18K show a process for depositing more than
two materials on a single layer, according to some embodiments of
the invention. In FIG. 18A, a substrate 108 is shown, onto which
patternable mold material 117 (for example, photoresist or solder
mask) has been deposited as shown in FIG. 18B. In FIG. 18C,
material 117 has been patterned (for example, if a photoresist, by
use of a photomask, developing, etc., by laser direct imaging, a
pattern generator and the like or, a combination of these methods)
to produce apertures. In FIG. 18D, first material 122 (for example,
a metal such as copper) has been deposited into the apertures (for
example, by electrodeposition).
[0275] In FIG. 18E, material 117 has been removed (for example, by
use of a chemical stripper) to expose regions of the substrate 108
which are not covered with first material 122. In FIG. 18F,
material 117 (or an alternative patternable mold material) is
deposited over first material 122 and patterned (FIG. 18G). In FIG.
18H, second material 123 (for example, a metal such as nickel) has
been deposited. In FIG. 18I, material 117 is removed. In FIG. 18J,
a third material 124 (for example, silver) has been blanket
deposited over materials 122 and 123. In FIG. 18K, the layer has
been planarized to a sufficient depth to remove all of second
material 124 overlying first material 122 and second material 123,
and also to establish a layer of the desired thickness, flatness,
and surface finish.
[0276] Various alternatives to the embodiment of FIGS. 18A-18K are
possible. For example, in some alternative embodiments, it may
possible to planarize materials 122 and 117 of FIG. 18D to a
desired height (e.g. equal to or greater than the layer thickness
or bounding height of the layer) prior to removal of material 117
as shown in FIG. 18E. In addition, or alternatively, it may be
possible to planarize material 117 deposited in FIG. 18F prior to
patterning it to obtain the void in material 117 as shown in FIG.
18G. The planarization may or may not cause material 122 to become
exposed but it is anticipated that the planar surface of material
122 may allow more accurate patterning of material 117 in obtaining
the result of FIG. 18G particularly if the void or voids to be
formed in material 117 are near or adjacent to the deposits of
material 122. Such planarization may allow the materials to be
pattern deposited adjacent to or in proximity to one another. It is
believed that these alternatives will work satisfactorily when the
patternable material, for example is a photoresist of the dry film
or liquid type, so long as it is adequately located within corners
between material 122 and the substrate or previously formed layer
of material. In still other alternative embodiments, it may be
possible to further pattern the first deposited patternable masking
material instead of removing it which was shown FIG. 18E such that
depositing a second patternable material as shown in FIG. 18F
becomes unnecessary.
[0277] Additional embodiments where three or more materials per
layer will be deposited are possible. Some of these additional
embodiments are focused on alternative techniques for allowing
patterned deposition of two or more materials adjacent to one
another. Detailed examples of such alternative embodiments are set
forth herein next as the first through third exemplary
embodiments.
[0278] Referring to FIGS. 19A-19K, a first exemplary embodiment is
shown for depositing more than two materials on the same layer
wherein two or more different materials (for example, metals) need
to be pattern deposited adjacent to each other. In FIG. 19A, a
substrate 108 is shown, onto which patternable mold material 117
(for example, photoresist or solder mask) has been deposited as
shown in FIG. 19B. In FIG. 19C, material 117 has been patterned
(for example, if a photoresist, by use of a photomask, developing,
etc., by laser direct imaging, a pattern generator and the like or,
a combination of these methods) to produce an aperture. In FIG.
19D, first material 122 (for example, a metal such as copper) has
been deposited into the aperture (for example, by
electrodeposition).
[0279] In FIG. 19E, material 117 has been removed exposing portions
of the substrate 108 not covered by first material 122. In FIG.
19F, another layer of material 117 is deposited over substrate 108
and first material 122. In FIG. 19G, material 117 (or an
alternative patternable mold material) is patterned to produce an
aperture adjacent to first material 122, as well as to expose a top
portion of first material 122. In FIG. 19G, it is shown that an
edge of the material 117 that is formed over first material 122 is
not aligned with an edge of first material 122, i.e., a portion of
the top surface of first material 122 is exposed. In FIG. 19H,
second material 123 (for example, nickel) is deposited into the
aperture and over the exposed portion of first material 122. In
FIG. 19I, material 117 is removed. In FIG. 19J, third material 124
(for example, silver) is blanket deposited over substrate 108,
first material 122 and second material 123. In FIG. 19K, the layer
has been planarized to a sufficient depth to establish a layer of
the desired thickness, flatness, and surface finish. It can be seen
in FIG. 19K that the portion of second material 123 that was
deposited over first material 122 has been removed. Thus, it was
not necessary that the edge of the material 117 that is formed over
first material 122 be aligned with an edge of first material 122.
Therefore, some embodiments of the invention purposely do not align
the edge, as shown in FIG. 19G. This may be beneficial in that
precise mask alignment is not necessary.
[0280] Referring to FIGS. 20A-20J, a second exemplary embodiment is
shown for depositing more than two materials on the same layer
wherein two or more different materials (for example, metals) are
adjacent to each other. In FIG. 20A, a substrate 108 is shown, onto
which patternable mold material 117 (for example, photoresist or
solder mask) has been deposited as shown in FIG. 20B. In FIG. 20C,
material 117 has been patterned (for example, if a photoresist, by
use of a photomask, developing, etc., by laser direct imaging, a
pattern generator and the like or, a combination of these methods)
to produce apertures. In FIG. 20D, first material 122 (for example,
a metal such as copper) has been deposited into the apertures (for
example, by electrodeposition) to a thickness substantially similar
to that of material 117. In FIG. 20E, a second layer of material
117 (or an alternative patternable mold material) is deposited
without stripping the first layer of material 117 so that the first
layer provides support for the second layer. It is assumed in the
present embodiment that material 117 is a patternable mold material
that may be patterned more than once.
[0281] In FIG. 20F, the two layers of material 117 have been
patterned to form apertures (including an aperture adjacent to
first material 122) and to expose a top portion of first material
122. In FIG. 20G, a second material (for example, nickel) is
deposited over the exposed areas of substrate 108 and first
material 122. In FIG. 20H, material 117 is removed. In FIG. 20I, a
third material 124 (for example, silver) is blanket deposited over
substrate 108, first material 122 and second material 123. In FIG.
20J, the layer has been planarized to a sufficient depth to
establish a layer of the desired thickness, flatness, and surface
finish.
[0282] Referring to FIGS. 21A-21I, a third exemplary embodiment is
shown for depositing more than two materials on the same layer
wherein two or more different materials (for example, metals) are
adjacent to each other. In FIG. 21A, a substrate 108 is shown, onto
which patternable mold material 117 (for example, photoresist or
solder mask) has been deposited as shown in FIG. 21B. In FIG. 21C,
material 117 has been patterned (for example, if a photoresist, by
use of a photomask, developing, etc., by laser direct imaging, a
pattern generator and the like or, a combination of these methods)
to produce apertures. In FIG. 21D, first material 122 (for example,
a metal such as copper) has been deposited into the apertures (for
example, by electrodeposition).
[0283] In FIG. 21E, material 117 is patterned again to produce
additional apertures. It is assumed in the present embodiment that
material 117 is a patternable mold material that may be patterned
more than once. In FIG. 21F, second material 123 (for example, a
metal such as nickel) is deposited into the additional apertures
(for example, by electrodeposition). In FIG. 21G, material 117 is
removed. In FIG. 21H, a third material 124 (for example, silver) is
blanket deposited over substrate 108 and second material 123. In
FIG. 21I, the layer has been planarized to a sufficient depth to
establish a layer of the desired thickness, flatness, and surface
finish.
[0284] Thus, unlike in the second embodiment discussed above,
according to the third embodiment, a second layer of patternable
mold material 117 is not used. Instead, the first layer of material
117 is patterned twice in order to deposit two or more different
materials that are adjacent to each other on the same layer. As a
result, the second-deposited material deposits over the
first-deposited material, making the entire thickness of deposit
greater and more planarization necessary to achieve the final layer
thickness. In comparison, the second embodiment discussed above,
where the second layer of mold material covers up much of the
second-deposited material, reduces this overall thickness.
[0285] Referring to FIGS. 22A-22I, a fourth exemplary embodiment is
shown for including two or more different materials (for example,
metals) that may be adjacent to each other on the same layer. In
FIG. 22A, a substrate 108 is shown, onto which an ablatable
material 125 is deposited, as shown in FIG. 22B. Ablatable material
125 may be any suitable material that is ablatable by, for example,
ultraviolet lasers. Examples of suitable ablatable materials
include, but are not limited to, polyimide, polyurethane, and the
like. In FIG. 22C, material 125 is ablated to produce an aperture.
In FIG. 22D, first material 122 (for example, a metal such as
copper) has been deposited into the apertures (for example, by
electrodeposition).
[0286] In FIG. 22E, material 125 is again ablated to produce an
additional aperture adjacent to first material 122. Ablation of
material 125 adjacent to material 122 may slightly reduce the
thickness of material 122 if the radiation used for ablation
overlaps material 122; however, by making material 122 thicker than
the desired ultimate layer thickness, this can be tolerated.
Moreover, by selecting the wavelength and/or intensity of such
radiation, selective ablation of material 125 with little effect on
material 122 may be achieved. In FIG. 22F, second material 123 (for
example, nickel) has been deposited (for example, by
electrodeposition) into the additional aperture and over the
exposed portion of first material 122. Assuming a total of three
materials on this layer, material 125 can now be completely removed
(for example, by ablation) as shown in FIG. 22G and--as shown in
FIG. 22H, a third material 124 (for example, silver) can be blanket
deposited over substrate 108, first material 122 and second
material 123. In FIG. 22I, the layer has been planarized to a
sufficient depth to establish a layer of the desired thickness,
flatness, and surface finish.
[0287] According to some embodiments of the invention, multiple
layers may be patterned using a single plating step to build an
expanding geometrical structure 126 on a substrate 108 such as that
shown in FIG. 23A, or a contracting geometrical structure 127 on a
substrate 108 such as that shown in FIG. 23B.
[0288] FIGS. 24A-24F illustrate an embodiment of a process for
forming the expanding geometrical structure 126 shown in FIG. 23A.
In FIG. 24A, a substrate 108 is shown, onto which patternable mold
material 117 (for example, photoresist or solder mask) has been
deposited. Material 117 is being exposed to light 128 (for example,
ultraviolet) that is preferably highly-collimated and which passes
through photomask 129 in clear regions of the mask to produce
exposed areas of patternable mold material 117'.
[0289] When an expanding geometry like that shown in FIG. 23A is
formed, some preferred embodiments of the invention use a negative
patternable mold material, i.e. one that becomes insoluble to the
developer in those regions exposed to light. By using a negative
patternable mold material, precise exposure control is not required
(i.e., precise control of depth of penetration of light 128,
exposure time, and the like). This is because exposure of the
current layer does not expose previously unexposed areas of the
layers below it due to the dark area of mask 129. Other embodiments
may use a positive resist and exercise precise exposure
control.
[0290] Succeeding layers of the structure 126 are exposed in a
similar manner, as shown in FIGS. 24B-24D. In FIG. 24E, the
unexposed portion of the material 117 is removed. In FIG. 24F, a
single plating step is performed which fills the pattern left by
the removal of material 117' with a material 130 (for example, a
metal). The patternable mold material acts as a mold for forming
structure 126. In FIG. 24G, the exposed portions 117' are removed,
leaving structure 126.
[0291] FIGS. 25A-25G illustrate an embodiment of a process for
forming the contracting geometrical structure 127 shown in FIG.
23B. In FIG. 25A, a substrate 108 is shown, onto which patternable
mold material 117 (for example, photoresist or solder mask) has
been deposited. Material 117 is being exposed to light 128 (for
example, ultraviolet) that is preferably highly-collimated and
which passes through photomask 131 in clear regions of the mask to
produce exposed areas of patternable mold material 117'.
[0292] When an contracting geometry like that shown in FIG. 23B is
formed, some preferred embodiments of the invention use a positive
patternable mold material, i.e. one that becomes soluble to the
developer in those regions exposed to light. By using a positive
patternable mold material, precise exposure control is not required
(i.e., precise control of depth of penetration of light 128,
exposure time, and the like). This is because exposure of the
uppermost layer does not expose previously unexposed areas of the
layers below the uppermost layer due to the dark area of mask 131.
Other embodiments may use a negative resist and exercise precise
exposure control.
[0293] Succeeding layers of the structure 127 are exposed in a
similar manner, as shown in FIGS. 25B-25D. In FIG. 25E, the exposed
portion of the material 117 is removed. In FIG. 25F, a single
plating step is performed which fills the pattern left by the
removal of material 117' with a material 132 (for example, a
metal). The patternable mold material acts as a mold for forming
structure 127. In FIG. 24G, the exposed portions 117' are removed,
leaving structure 127.
[0294] According to other embodiments of the invention, both the
expanding geometric structure and the contracting geometric
structure processes described above may develop the patternable
mold material after each exposure. In this case, preferred
embodiments may use a dry film resist as the patternable mold
material. The dry film resist is used such that the resist will
"tent" over apertures formed in the layers.
[0295] According to some embodiments of the invention, when
multiple layers are patterned using a single plating step, a seed
layer may first be deposited before the plating step if an angle
(such as the exemplary angle 133 shown in FIG. 26) is above a
critical angle 133. As shown in the flowchart of FIG. 27, some
embodiments of the invention may analyze features on a layer
(S2701) to determine whether any angle of a feature is above a
critical angle (S2701). If an angle of a feature is not above the
critical angle, no seed layer will need to be deposited (S2703).
However, if the angle is above the critical angle, a seed layer
will need to be deposited (S2704) to ensure that material can be
plated over the mold material (by `mushrooming` in some cases). The
angle analysis may be performed, for example, by a suitable
processing device running a suitable software program, or may be
performed by hardware, firmware or a combination thereof.
[0296] Referring now to FIG. 5BB, carrier 1 and all that is
attached to it has been placed on a fixture such that pins 93 enter
into holes 15. In addition, material 59 has been removed (for
example, by dissolution). In FIG. 5CC, material 23 has been melted
(preferably by activation of elements 17) such as to release
substrate 25. Alternatively, material 23 may also be removed
chemically. In FIG. 5DD, carrier 1 has been pushed down further
onto pins 93 such that substrate 25 is entirely free of carrier 1
and material 31 has either delaminated from carrier 1 or has become
torn as shown. The spaces left by the removal of material 59
enables easier delamination of the carrier 1 because there is no
buildup of the layer materials in the space occupied by material
59.
[0297] In FIG. 5EE, substrate 25 has been removed from the carrier
1 and placed on support 93 (for example, dicing tape). In FIG. 5FF,
kerfs 95 have been cut through all deposited materials as well as
through substrate 25 to singulate individual portions of substrate
25 into individual die. According to other embodiments, the kerfs
may be cut prior to removal of substrate 25 from carrier 1. Such
kerfs may be cut, for example, by resin or metal-bonded diamond
dicing saw blades, by toothed dicing saw blades, or by using a
laser or high-pressure fluid jet. Scrap die 99, including regions
of structural materials such as 79, no longer connect to die 97 and
may now be separated from die 97.
[0298] In FIG. 5GG, materials 63, 89, and 92 have been removed (for
example, by chemical dissolution selective to materials 65, 91, and
94. In FIG. 5HH, material 31 has been removed using a timed etching
step such that it is removed from most of substrate 25 but remains
substantially under features of material 65, though with some
undercutting 100 of said features. Finally, in FIG. 5II, support 93
has been removed from die 97, and die 97 have been separated from
one another. If desired, these removal processes may be performed
prior to dicing substrate as described above.
[0299] In previously described embodiments, the alignment targets
may be attached to a carrier to which the EFAB substrate is
affixed. Other embodiments of the invention provide methods of
providing alignment targets in the substrate itself, in case a
carrier is not used, or the carrier is not sufficiently large
relative to the substrate, or it is not desired to incorporate the
targets in the carrier for other reasons. According to some
embodiments of the invention, the targets can be located in a
variety of locations on the substrate. For example, the targets may
be located in unused die sites, near the edge of the wafer outside
the functional die, in the dicing lanes, and the like.
[0300] As in the previous embodiments, the embodiments described
below align all newly-added layers again and again to the same
alignment targets rather than align each new layer to an alignment
target formed in the previous layer. However, according to these
embodiments, the alignment targets are located on the substrate
rather than on the carrier, as in the previously described
embodiments. Aligning to targets on the substrate or carrier
instead of to targets in the previous layer avoids the accumulation
of errors, including the error produced by alignment targets on
each new layer not being identical in shape or size to that of
others on previous layers.
[0301] According to some embodiments of the invention, as shown in
FIGS. 29A-29X, the targets may be formed by electrodepositing or
otherwise depositing material onto the substrate (for example, by
sputtering). The targets may also be formed using lift-off
approaches, etching and the like. The targets are then covered with
a dielectric material so as to avoid plating over them (which would
obscure the targets as layers are added). FIG. 29A shows a
substrate 150 which has been coated with a patternable mold
material 151 (for example, a photoresist) in FIG. 29B. In FIG. 29C,
material 151 has been patterned to form apertures such as 152 into
which material 153 is then deposited (for example, by sputtering,
vacuum deposition, electrophoretic deposition, and the like) as
shown in FIG. 29D to form targets 154 as shown in FIG. 29E.
[0302] In FIG. 29E, material 151 has been removed. In FIG. 29F, a
resist or other patternable material 155 has been applied and in
FIG. 29G material 155 has been patterned to form an aperture 156
wider than and fully including target 154. Aperture 156 is made
large enough such that `mushrooming` of deposited materials which
might occur while forming subsequent layers of the
electrochemically-fabricated device cannot optically obscure
targets 154. In FIG. 29H, dielectric material 157 has been
deposited into aperture 156 and non-adherent material 158 (for
example, Teflon.RTM., SYTOP.RTM. or parylene) has preferably been
deposited on top of dielectric material 157 (if material 157 is
itself non-adherent material 158 may be omitted).
[0303] According to some embodiments of the invention, the total
thickness of materials 157 and 158 may be made small enough that
neither may come into contact with the lapping or polishing plate
during planarization of the first layer and therefore will not be
damaged or altered; this is the approach assumed in FIG. 29.
Alternatively, material 158 (or material 157 if material 158 is not
used) may be deposited to a thickness that ensures that it will be
lapped and/or polished (for example, along with the first layer of
the electrochemically-fabricated device). The planarization
operation then would be performed so as to provide an optically
smooth and transparent surface.
[0304] If materials 154, 157, and 158 are not electrodeposited,
portions of these materials would also be deposited onto materials
151 and 155, respectively, but these would be removed upon removal
of materials 151 and 155 (for example, during a lift-off process).
Also note that materials 154, 157, and 158 might also be deposited
in a blanket fashion and then patterned using etching (for example,
using a photoresist).
[0305] In FIG. 29I, material 155 has been removed and
fully-encapsulated, non-conductive, non-adherent alignment target
154 remains behind. The EFAB process can now begin. The remaining
FIGS. 29J-29R assume an EFAB process based on photoresist or other
adherent patternable material (hereinafter assumed to be resist).
However, embodiments they are equally applicable to an EFAB process
using an INSTANT MASK.TM..
[0306] In FIG. 29J, resist 159 has been applied. In FIG. 29K,
resist 159 has been patterned to produce apertures 160. In FIG.
29L, material 161 has been electrodeposited into apertures 160, and
in FIG. 29M resist 159 has been stripped. In FIG. 29N material 162
has been electrodeposited onto the substrate, filling the apertures
left behind by the removal of resist 159, and not depositing over
material 158 due to its insulating nature. However, due to the
ability of electrodeposits to `mushroom` over the edges of
insulators, material 162 slightly overlaps the edges of material
158 as shown. In FIG. 29O, the layer of materials 161 and 162 has
been planarized (in the case shown, the planarization plane is
above the surfaces of materials 157 and 158), completing the first
EFAB layer.
[0307] In FIG. 29P, resist 159 has been applied to the first layer
and in FIG. 29Q regions of resist 159 have been removed
mechanically (especially for dry film resist) or by chemical
stripping (for any type of resist) to form windows 163. According
to some embodiments of the invention, if electrodeposited resist is
used, targets 154 (since they are coated with at least one
insulating material) will not accumulate resist and thus no removal
of resist covering targets 154 is required. In some embodiments,
mechanical removal might involve use of a punch or cutting blade,
possibly combined with a vacuum or mechanical tweezers to extract
loosened pieces, especially of dry film resist. The non-adherent
nature of material 158 helps in this removal process, especially
for dry film resist. According to some embodiments, resist 159 may
be applied so as not to fill in windows 163. According to other
embodiments, resist 159 may be left filling windows 163, if it is
sufficiently transparent and non-distorting to not have a
detrimental effect on targets 154.
[0308] Referring to FIG. 29R, photomask 164 has been aligned to
targets 154 visible through windows 163 and resist 159 is exposed
to UV light 165. In FIG. 29S, resist 159 is developed to yield
apertures which are then electrodeposited with material 161 in FIG.
29T. At this time, material 161 is also deposited slightly over
material 158 to form a mushroomed region 166, slightly reducing the
size of windows 163. In FIG. 29U, material 162 has been deposited
and materials 161 and 162 have been planarized to yield the second
EFAB layer. Material 162 has been deposited over region 166,
further reducing the size of windows 163 and forming a mushroomed
region 167. It should be noted the none of the FIGS. are to scale
and that normally electrodeposited material mushrooms much more
isotropically than is shown in the FIGS.
[0309] In FIG. 29V, resist 159 has been applied to the second layer
and in FIG. 29W regions of resist 159 have again been removed so as
not to cover windows 163. Finally, in FIG. 29X, materials 161 and
162 have been deposited as with previous layers, again using
windows 163 to allow alignment between photomask targets and
targets 154. Also, materials 161 and 162 have been planarized to
yield the third EFAB layer. Materials 161 and 162 have formed
mushroomed regions 168 and 169, respectively, further reducing the
size of windows 163. Additional layers can be built in a similar
fashion, preferably continuing to use targets 154 for alignment so
long as they are not obscured by mushroomed regions of deposited
materials.
[0310] In a variation of the embodiment shown in FIGS. 29A-29X,
material 153 may be the same as material 161 or 162 and the two
deposited together (however, material 161 or 162 in the region of
targets 154 needs to be deposited to a lower height so that it is
below the planarization plane for the first layer. In another
variation of this embodiment, materials 157 and 158 may be solid
materials (for example, Teflon.RTM.-coated glass) that are placed
over targets 154 and secured (for example, by gluing or by the
mushrooming effect of subsequent plating). According to some
embodiments of the invention, such solid material may intentionally
be planarized to establish a smooth optical surface reasonably
parallel to substrate 150 if desired. In another variation of this
embodiment, targets 154 may be formed by etching features into
substrate 150 in lieu of by depositing material 153.
[0311] FIGS. 30A-30R illustrate another embodiment of the
invention, which can be used with dielectric substrates or else
with metal substrates on which the area of the alignment target is
insulating or is covered with an insulating material. In this
embodiment, the alignment targets are formed, for example, in the
adhesion and/or seed layers (for example, Ti and Au, respectively)
that coat the dielectric substrate, and the targets are
electrically isolated from the surrounding metal layers by an
insulating gap so that they are not able to be plated onto.
[0312] FIGS. 30A-30R assume the alignment targets are patterned
using a lift-off approach, but other approaches may be used in
other embodiments. Etching of blanket-deposited adhesion and/or
seed layers using a photoresist or similar material is one such
approach. Another approach is to plate the targets on top of the
adhesion and/or seed layers and then etch these layers back using a
time-controlled etch such that the material of the plated targets
avoids excessive undercutting of the adhesion and/or seed
layers.
[0313] Dielectric substrate 170 shown in FIG. 30A is covered with
resist 171 (FIG. 30B) which is patterned (FIG. 30C), preferably
with sidewalls having a negative slope (undercut), as is the norm
in lift-off patterning. In FIG. 30D metal(s) have been deposited to
form an adhesion/seed layer 172. In FIG. 30E resist 171 has been
removed, leaving patterned layer 172. The patterning operation both
patterns alignment targets 173 and disconnects them electrically
from the remainder of the layer 172.
[0314] FIG. 31 shows a top view of substrate 170, layer 172, and
targets 173. The bare area of substrate 170 surrounding targets 173
is made large enough such that `mushrooming` of deposited materials
while forming subsequent EFAB layers cannot optically obscure
targets 173. Even if dry film resist is used in subsequent
processing, this is likely to become laminated to the alignment
target in making the first few layers, since the distance to the
target is small. Therefore, in some embodiments, targets 173 may be
coated with a non-adherent material (not shown) similar to that
described above so that resist applied over them can be easily
removed.
[0315] Referring to FIG. 30F resist 174 has been applied to pattern
the first EFAB layer. In FIG. 30G resist 174 has been patterned to
produce apertures and in FIG. 30H material 175 has been
electrodeposited into these apertures. In FIG. 30I, resist 174 has
been stripped and in FIG. 30J material 176 has been
blanket-deposited. A mushroomed region 177 has been produced
alongside the patterned edge of layer 172.
[0316] In FIG. 30K, materials 175 and 176 have been planarized to
yield the first EFAB layer. In FIG. 30L, resist 174 (dry film
resist is assumed in the figure, `tenting` over targets 173) has
been applied to the first layer. In FIG. 30M, the portion of resist
174 over targets 173 has been removed mechanically (especially for
dry film resist) or by chemical stripping (for any type of resist)
to form windows 179. In embodiments wherein electrodeposited resist
is used, targets 173 (since they are electrically isolated) will
not accumulate resist and thus no removal of resist covering
targets 173 is required. In some embodiments, mechanical removal
might involve use of a punch or cutting blade, possibly combined
with a vacuum or mechanical tweezers. According to some embodiments
of the invention, resist 174 may be applied so as not to fill in
windows 179. In some embodiments, resist 174 may also be left
filling windows 179, if it is sufficiently transparent and
non-distorting to not have a detrimental effect on targets 173.
[0317] In FIG. 30N, resist 174 is patterned by using targets 173
for alignment. In FIG. 30O, material 175 has been deposited. A
mushroomed region 178 has been produced alongside the edge of the
first layer, surrounding targets 173.
[0318] In FIG. 30P, resist 174 has been stripped and in FIG. 30Q
material 176 has been blanket deposited. A mushroomed region 180
has been produced over mushroomed region 178. In FIG. 30R materials
175 and 176 have been planarized. Additional layers can be built in
a similar fashion, preferably continuing to use targets 173 for
alignment.
[0319] The methods of the above embodiments can also be used to
incorporate a human and/or machine-readable identification code
(e.g., a bar code or the like) into the surface of the substrate as
a method of identifying the substrate, particularly one that is not
attached to a carrier bearing an identifying tag. This can be done
in the same manner as, and along with, alignment targets that are
incorporated as described above, such that deposition of material
is substantially prevented from occurring above the identification
code and obscuring it from view.
[0320] In a variation of the embodiments shown in FIGS. 29 and 30,
the targets may be covered by a solid material (for example, a
light tack tape such as dicing tape) or `plug` to protect the
targets from contact with the resist and allowing the resist to
easily be removed from the targets without leaving any residue
behind.
[0321] FIGS. 59A-59I show a further embodiment of the invention for
forming a target on a substrate. As shown in FIG. 59A, a substrate
400 is shown, onto which a adhesion/seed layer 402 has been
deposited as shown in FIG. 59B. In FIG. 59C, patternable mold
material 404 (for example, a photoresist) has been deposited. In
FIG. 59D, patternable mold material 404 has been patterned to form
apertures. In FIG. 59E, portions 406(a) and 406(b) comprised of a
first material 406 (for example, nickel) have been formed in the
apertures. Portion 406(a) will be a target, while 406(b) will be a
device or structure.
[0322] In FIG. 59F, a second material has been blanket deposited
over adhesion/seed layer 402 and 406(a) and 406(b). In FIG. 59G,
planarization has been performed. In FIG. 59H, second material 408
surrounding portion 406(a) has been removed, for example by local
etching, leaving only the adhesion/seed layer 402 around portion
406(a). In FIG. 59I, the adhesion/seed layer 402 around portion
406(a) has been removed, for example, by local etching.
[0323] Thus, the embodiment for forming a target on a substrate
described above first forms a layer of materials on an
adhesion/seed layer. Then, at least one of the materials and the
adhesion/seed layer is removed to electrically isolate the target
by forming an island of non-conductive material around the target.
In this manner, the target will not be plated onto during a
subsequent plating process. According to some embodiments of the
invention, an additional etching and/or polishing step may be
performed on the nickel to remove any smearing or scratching that
may have resulted from the planarization step.
[0324] In previously described embodiments, the alignment targets
may be attached to a carrier to which the EFAB substrate is affixed
or to an EFAB substrate. Yet other embodiments of the invention
provide methods of providing alignment targets in the previous
layer for alignment of a photomask to the previous layer. After a
layer consisting of structural and sacrificial materials is formed,
there may be difficulty in forming high-quality targets because of,
for example, smearing of one material into another, poor contrast
between various materials (e.g., structural and sacrificial) in the
layer, and/or surface roughness. These problems may result from
planarization and may be more acute if two or more materials on the
layer are close in color. When these problems exist, it may be
difficult for a machine vision system (or operator) to identify and
accurate locate the targets.
[0325] Thus, according to some embodiments of the invention,
etching of the area of the targets may be performed to enhance the
contrast. Other embodiments may also or in the alternative, polish
the area of the targets to remove scratches and smear due to the
planarization step. In some cases, the effects of planarization on
different targets may be dependent, for example, on a particular
target's location on the layer. For example, one target located in
a particular area of the layer may be more detrimentally affected
by planarization than another target in a different location of the
layer. Thus, according to some embodiments of the invention,
multiple alignment targets may be located on the layer in order
that, for example, the more detrimentally affected targets may be
rejected or an average position calculated from among multiple
targets.
[0326] As stated above, some embodiments of the invention may align
a mask to a previous layer based on targets located in the previous
layer. An exemplary shape of a target that may be located on a
previous layer is shown in FIG. 32A. An exemplary shape that may be
used on a mask to align to the target is shown in FIG. 32B. FIG.
32C shows the shapes of FIGS. 32A and 32B as they would appear with
proper alignment of the mask to the previous layer.
[0327] Some embodiments of the invention provide masks that include
both shapes that are used to align the photomask to a target on a
previous layer ("alignment shapes") and shapes that are used to
form new targets on the layer currently being patterned ("new
target shapes") in preparation for alignment of the subsequent
layer.
[0328] Referring to FIGS. 33A-33D, some embodiments of the
invention provide odd and even layer masks that have alternating
patterns of alignment shapes and new target shapes. FIG. 33A shows
a first mask (Mask 1) having shapes that are used to form new
targets on a first layer (layer 1). Also shown in FIG. 33A is a
first layer (Layer 1) showing a completed two-material layer after
patterning of the first material using Mask 1.
[0329] FIG. 33B shows a second mask (Mask 2) having both alignment
shapes used to align the photomask to the targets previously
patterned on the first layer and new target shapes for forming new
targets on a second layer (Layer 2). Layer 2 also shows the layer
produced using Mask 2. It can be seen that when the alignment
shapes on the second mask are properly aligned with the targets to
be patterned on the first layer, new targets may also be formed on
the second layer using the new target shapes on the second
mask.
[0330] FIG. 33C shows a third mask (Mask 3) having both alignment
shapes used to align the photomask to the targets previously
patterned on the second layer and new target shapes for forming new
targets on a third layer (Layer 3). Layer 3 also shows the layer
produced using Mask 3. It can be seen that when the alignment
shapes on the third mask are properly aligned with the targets to
be patterned on the second layer, new targets may also be formed on
the third layer using the new target shapes on the third mask.
[0331] FIG. 33D shows a fourth mask (Mask 4) having both alignment
shapes used to align the photomask to the targets previously
patterned on the third layer and new target shapes for forming new
targets on a fourth layer (Layer 4). Layer 4 also shows the layer
produced using Mask 4. It can be seen that when the alignment
shapes on the fourth mask are properly aligned with the targets to
be patterned on the third layer, new targets may also be formed on
the fourth layer using the new target shapes on the fourth mask. In
addition to alignment shapes and new target shapes, masks may
contain vernier-type shapes to allow the accuracy of alignment to
be evaluated. The positions of such shapes would also change from
even to odd layers on alternating masks.
[0332] It may be desirable to reduce the number of photomasks
required to build a structure through methods of mask minimization
already described in U.S. Pat. No. 6,027,630. The method described
in this patent for reusing photomasks may be modified according to
some embodiments of the invention using software algorithms such
that an existing or planned photomask for an even layer can be used
in lieu of generating a new photomask for an even layer, but not
for an odd layer, and vice-versa, in the case that alignment
targets, verniers, or other alternating structures are needed as
described above.
[0333] Generally, a photomask is used to build structures across an
entire substrate. However, there may be cases (e.g., the fabricate
of prototype quantities) where only a quarter or a half of the
substrate is needed for the structures. For example, it may be
desirable to build a multiple layer structure while only using, for
example, one quarter or one half of the substrate. Conventionally
one might choose to build on a smaller substrate and perhaps use
smaller (and less costly) photomasks as a result. However, this
approach requires specialized tooling and possibly equipment for
processing a substrate of smaller size, and does not ensure that
the processing conditions and thus behavior of the devices produced
on the smaller substrate will be identical to those produced
(typically in larger quantity) on the larger substrate.
Conventionally, a different photomask may be necessary for each
layer of the structure, adding significantly to the cost of
fabricating the structure, even if only a small quantity of devices
are needed.
[0334] In order to reduce the cost involved in using multiple
photomasks, particularly when producing small or prototype
quantities, some embodiments of the invention advantageously place
multiple patterns (each pattern for exposing a different layer of
the same structure located on some portion of the substrate) onto a
single photomask.
[0335] Referring to FIG. 34A, according to some embodiments of the
invention, substrate 134 is shown as having four quadrants 135,
136, 137 and 138. The two arrows shown in quadrant 135 of substrate
134 represent an particular orientation of a layer to be exposed.
The X in the remaining quadrants 136, 137 and 138 represents a
"don't care" condition. In other words, the only portion of the
substrate 134 intended to yield usable structures is quadrant
135.
[0336] Referring to FIG. 34B, according to some embodiments of the
invention, photomask 139 is also shown as having four quadrants
140, 141, 142 and 143, each having two arrows that represent a
pattern having a particular orientation. Each of quadrants 140-143
are used to expose an individual successive layer of a structure
that is to be fabricated in quadrant 135 of substrate 134. Also,
each quadrant is shown with a number 1-4 representing the order in
which the photomask is applied for four individual successive
layers to be exposed in quadrant 135.
[0337] When the photomask 139 is used to expose the layers in
quadrant 135, quadrant 140(1) of the photomask is used in
patterning the first of the four successive layers. This is because
quadrant 140 has the pattern on the photomask that is initially in
the correct orientation relative to quadrant 135 of substrate
134.
[0338] Then, according to some embodiments of the invention, the
photomask 139 is rotated (in this example, counterclockwise) by 90
degrees, such that the pattern in quadrant 141(2) is in the correct
orientation relative to quadrant 135 of substrate 134. The
photomask is then used to pattern the second of the four successive
layers.
[0339] The same process is repeated for quadrants 142(3) and 143(4)
in order to pattern the third and fourth of the four successive
layers, respectively. It is apparent from FIGS. 34A-34B that the
"don't care" quadrants 136, 137 and 138 will have no value since
the layers will not be in the correct thickness and moreover (if
different layers are fabricated with different thicknesses) will
not necessarily have the correct thicknesses. However, generally
speaking, substrates such as substrate 134 are less costly than a
set of photomasks such as photomask 139. Thus, even though a
portion of the substrate 134 is not used, the economical use of the
photomask leads to an overall cost savings for the fabrication
process.
[0340] Although the embodiment described above divided the
substrate and the photomask into quadrants, other embodiments may
divide the substrate and the photomask into halves, with half of
the substrate yielding usable structures. In this case, two layers
could be patterned using the photomask, with a 180 degree rotation
of the photomask being performed after the first layer is patterned
and before patterning the second layer. Other embodiments may use
other divisions of the substrate and photomask, with appropriate
rotation and/or translation in an appropriate direction after each
successive layer.
[0341] When using the above embodiments it may be desirable to cut
the substrate so as to remove the "don't care" quadrants or "don't
care" half prior to releasing the structures; otherwise corrupted
structures in these quadrants may become detached from the
substrate while in the etchant bath and become entangled with or
otherwise damage the desired structures. In some embodiments the
photomask quadrants or halves may not be used successively (i.e.,
quadrants 140-143 used to pattern layers in strict sequence).
[0342] If it is desired to fabricate more than a single quadrant or
half of a substrate that yields usable structures, the above
embodiments can be modified by incorporating a secondary mask which
blocks light from passing through the photomask in some regions,
and performing multiple exposures for each layer. For example, if
the photomask is divided into quadrants, the secondary mask would
normally be designed so as to prevent three out of four of the
substrate quadrants from being exposed. The secondary mask would
then be rotated in synchronization with the photomask, and up to
three more exposures would then be made, thus exposing more of
substrate completely to the correct pattern for a given layer
(structures would be oriented differently depending on which
substrate quadrant they were located in).
[0343] More generally, the embodiments described above may be used
to reduce the number of photomasks required, with a more arbitrary
assignment of photomask quadrants to device layers (e.g., quadrant
140 patterning layer 6, quadrant 141 patterning layer 2, etc.).
However, it may still be necessary to pay attention (due to the
need for alignment shapes and target shapes in particular
locations) to which layer patterns are in which quadrants. For
example, instead of placing the patterns for layers 1, 2, 3, and 4
on a first photomask and the patterns for layers 5, 6, 7, and 8 on
a second photomask, one might put the patterns for layers 1, 4, 7,
2 (in that order of clockwise or counterclockwise rotation) on the
first photomask and the patterns for 3, 8, 5, 6 (in that order) on
the second photomask: such an arrangement would preserve the layout
of even- and odd-numbered layer patterns.
[0344] In addition, although the embodiment described above used
photoresist as an example of a patternable mold material, the
embodiments discussed above would also be applicable to INSTANT
MASKS.TM. and other suitable patternable mold materials. Also,
although the embodiment described above rotated the photomask while
the substrate remained fixed, a reverse process is also possible,
i.e., the substrate may be rotated a suitable amount (for example,
90 degrees) while the photomask remains fixed.
[0345] According to some embodiments of the invention, additional
alignment targets are used in proportion to the number of rotations
required. Using these additional alignment targets, some
embodiments of the invention as described below allow multiple odd
and even layers to be patterned using a single mask by rotating of
the mask to produce alternating layouts of alignment shapes and new
target shapes.
[0346] As an example, FIG. 35A shows photomask 139 from FIG. 34B as
having four quadrants with 90 degree differences in orientation as
described above. Each of quadrants 140-143 are used in patterning
an individual successive layer of a structure that is to be
fabricated in quadrant 135 of substrate 134. Also, each quadrant is
shown with a number 1-4 representing the order in which the
photomask is applied for four individual successive layers to be
patterned in quadrant 135.
[0347] In FIG. 35B, photomask 139 is also shown as having two pairs
of alignment shapes used to align the photomask to the targets on a
previous layer on substrate 134 and two pairs of new target shapes
for forming new targets on the layer currently being patterned on
substrate 134.
[0348] As discussed above, according to some embodiments of the
invention, a first quadrant 140 of photomask 139 is used in
patterning a first layer in quadrant 135 of substrate 134. It is
assumed in the present embodiment that a layer formed previous to
the current layer to be patterned included alignment targets that
may be aligned with alignment shapes 182 and 183. According to some
embodiments of the invention, during the same patterning step, new
target shapes 184 and 185 are used in patterning new targets in the
layer currently being patterned in quadrant 135.
[0349] After patterning the layer having the pattern of quadrant
140 of photomask 139, photomask 139 may be rotated a particular
amount and direction (90 degrees in a counterclockwise direction in
the current embodiment) such that the pattern in quadrant 141(2) is
in the correct orientation relative to quadrant 135 of substrate
134 in order to pattern a succeeding layer in quadrant 135, as
illustrated in FIG. 35B. FIG. 35B shows the position of photomask
139 relative to substrate 134 after such rotation. Alignment shapes
188 and 191 may now be aligned with the targets formed on the
previously patterned layer by new target shapes 184 and 185.
According to some embodiments of the invention, during the same
patterning step, new target shapes 189 and 190 are used to pattern
new targets in the layer currently being patterned in quadrant 135.
It should also be noted that other pairs of alignment shapes and
target shapes are available 90 degrees from those discussed above
and these may also be used for alignment if accessible to the mask
aligner.
[0350] Thus, it can be seen that some embodiments of the invention
as described above allow multiple odd and even layers to be
patterned using a single mask wherein rotation of the mask produces
alternating patterns of alignment shapes and new target shapes,
thus resulting in a reduction in the number of photomasks required
to produce structures and a corresponding reduction in the cost of
fabrication. In the case in which two patterns (vs. four) are
incorporated into the photomask and a 180 degree (vs. 90 degree) is
used, the alignment shapes and target shapes would be positioned
typically symmetrically about the centerline of the mask as shown
in the photomask of, for example, FIG. 33B. Rotation by 180 degrees
of such a photomask relative to the substrate would automatically
create the alignment shapes and target shape layout of, for
example, FIG. 33C.
[0351] According to other embodiments of the invention, mask usage
may be minimized through using both a single photomask to expose a
layer and, in addition, using laser direct imaging, a pattern
generator or other suitable means for modifying the exposure that
has or will be performed using the photomask. In this manner, for
example, an initial pattern for forming a desired final
feature--but varying slightly from the desired final feature--may
be initially patterned in a patternable mold material using only a
single photomask. Then, the initial pattern may be slightly
modified using, for example, laser direct imaging to produce the
desired final feature. According to some embodiments of the
invention, an analysis may be performed, for example, on a layer by
layer basis to determine areas on a layer where such modification
techniques would be possible and desirable in lieu of creating a
new mask in order to achieve the desired pattern of exposure. This
analysis may be performed, for example, by a suitable processing
device running a suitable software program, or may be performed by
hardware, firmware or a combination thereof.
[0352] According to further embodiments of the invention, foreign
objects may be incorporated within layers formed on a substrate.
Examples of foreign objects may include, but are not limited to,
ball bearings, integrated circuits, lenses, mirrors, fiber optic
strands, needle probes or other objects that cannot easily be
manufactured during an EFAB process due to geometry limitations or
materials limitations.
[0353] FIGS. 37A-37P show a process for incorporating objects
within layers formed on a substrate, according to some embodiments
of the invention. As shown in FIG. 37A, a substrate 202 is shown,
onto which patternable mold material 204 (for example, photoresist
or solder mask) has been deposited as shown in FIG. 37B. In FIG.
37C, material 204 has been patterned (for example, if a
photoresist, by use of a photomask, developing, etc., by laser
direct imaging, a pattern generator and the like or, a combination
of these methods) to produce aperture 201. In FIG. 37D, one or more
objects 206 (in the present example objects 206 are balls) are made
to fall into aperture 201, for example by flowing the objects 206
onto the surface 203 of patternable mold material 204, for example
in a liquid medium. According to other embodiments, where objects
206 are balls or other spherical objects, the objects may be rolled
onto the surface 203. Alternatively, objects 206 may be poured onto
the surface 203, and those objects not falling into an aperture may
be squeegeed off the surface 203 or otherwise removed as shown in
FIG. 37E. Other embodiments may use other methods for placing
objects 206 into apertures such as aperture 201. For example, a
pick and place machine or other suitable machine may be used to
place the objects into the apertures.
[0354] In FIG. 37F, another patternable mold material 208 has been
deposited in order to cap the object 206, i.e., to secure object
206 within aperture 201. According to some embodiments, material
208 may be a dry film resist. According to other embodiments,
patternable mold material 208 may be the same type of material as
patternable mold material 204 or some other suitable patternable
mold material. According to some embodiments, forming patternable
mold material 208 over object 206 may be unnecessary if, for
example, sufficient care is used such that the object 206 does not
fall out of aperture 201.
[0355] In FIG. 37G, patternable mold material 208 has been
patterned to produce aperture 205. In FIG. 37H, a first material
210 (for example, a metal such as copper) has been formed (for
example by electrodeposition through aperture 205) in aperture 201
to at least partially encase and secure the object 206 within
aperture 201. First material 210 is a sacrificial material,
according to the embodiment of the invention shown in FIG. 37. In
FIG. 37I, patternable mold material 204 has been removed (for
example, by use of a chemical stripper) to expose regions of the
substrate 202 which are not covered with first material 210. In
FIG. 37J, a patternable mold material 212 has been deposited over
substrate 202 and material 210. Patternable mold material 212 may
be, for example, a dry film resist or a suitable liquid resist.
[0356] In FIG. 37K, patternable mold material 212 has been
patterned to produce apertures 207 and 209. First material 210 is
then deposited into apertures 207, 209, as shown in FIG. 37L.
Although according to the present embodiment first material 210 is
deposited as shown in FIG. 37L, according to other embodiments a
material different from first material 210 (for example, a
different metal) may be deposited instead. In FIG. 37M, patternable
mold material 212 has been stripped. In FIG. 37N, second material
214 has been blanket deposited (for example by electrodeposition)
to fill apertures 207, 209. Second material 214 may be a material
different from first material 210 (for example, a different
metal).
[0357] In FIG. 37O, materials 210 and 214 have been planarized to a
sufficient depth to remove all of second material 214 overlying
first material 210, and also to establish a layer of the desired
thickness, flatness, and surface finish. As shown in FIG. 37O, the
level of planarization 211 may be set to be above the upper level
of object 206. Alternatively, in other embodiments, it may be
desirable to planarize to some level below the upper level of
object 206. In that case, an upper portion of the object itself may
be planarized.
[0358] FIG. 37P shows an exemplary product of the above-described
process after additional layers have been formed on the substrate
202 and first material 210 has been removed, according to some
embodiments of the invention. Thus, as shown in FIG. 37P, multiple
layers of second material 214 remain to form a structure on
substrate 202 that has object 206 incorporated in a layer of the
structure.
[0359] FIGS. 38A-38P show another embodiment of the invention for
incorporating foreign objects within layers formed on a substrate.
The exemplary process shown in FIGS. 38A-38C and 38H-38P are
identical to the corresponding process steps shown in FIGS. 37A-37C
and 37H-37P and described above. Thus, these process steps will not
be described further. The exemplary process shown in FIG. 38
differs from that shown in FIG. 37 only as shown in FIGS. 38D-38G,
as will be described below.
[0360] As shown in FIG. 38D, after aperture 201 is formed in
patternable mold material 204, a second patternable mold material
216 is formed over patternable mold material 204 and aperture 201.
Patternable mold material 216 may be, for example, a photoresist
that is deformable. According to some embodiments, patternable mold
material 216 may preferably be an elastic or semi-elastic material.
In FIG. 38E, aperture 213 is formed in patternable mold material
216. In FIG. 38F, objects 206 are flowed or otherwise deposited
onto the surface 203 patternable mold material 216.
[0361] In FIG. 38G, one or more objects 206 are forced into
aperture 201 through the aperture 213 formed in the deformable
patternable mold material 216 and remains secured in the aperture
by patternable mold material 216. Thus, some embodiments of the
invention as shown in FIG. 38 differ from those shown in FIG. 37 in
that the second layer of patternable mold material 216 is formed
before objects 206 are incorporated into a layer and an object 206
is inserted through an aperture 213 formed in the patternable mold
material 216 into aperture 201.
[0362] FIG. 39 shows a top view of a step in the formation of a
ball bearing structure formed according to some embodiments of the
invention. FIG. 39 shows patternable mold material 218 formed over
apertures 215 to secure balls 220 within the apertures 215.
Patternable mold material 218 has been patterned to include stripes
217 that prevent the balls 220 from falling out of apertures 215,
but allow deposition of a material into apertures 215 on either
side of stripes 217. FIG. 40 shows a completed ball bearing
structure formed according to some embodiments of the invention.
Balls 220 move freely in a track 222 that is formed between inner
structural material 224 and outer structural material 226.
[0363] FIGS. 41A-41K show another embodiment of the invention for
incorporating foreign objects within layers formed on a substrate.
As shown in FIG. 41A, a substrate 228 is shown, onto which
patternable mold material 230 (for example, photoresist or solder
mask) has been deposited as shown in FIG. 4I B. In FIG. 4I C,
material 230 has been patterned (for example, if a photoresist, by
use of a photomask, developing, etc., by laser direct imaging, a
pattern generator and the like or, a combination of these methods)
to produce apertures 219 and 221. In FIG. 4I D, a first material
232 (for example, a metal such as copper) has been formed (for
example by electrodeposition) in apertures 219, 221. In FIG. 41E,
patternable mold material 230 has been stripped. In FIG. 4I F, a
patternable mold material 234 has been formed over first material
232. Patternable mold material 234 may be, for example, a dry film
resist or a suitable liquid resist.
[0364] In FIG. 4I G, patternable mold material 234 has been
patterned to expose areas of substrate 228 and first material 232.
In FIG. 41H, a second material 236 (for example, a metal such as
nickel) has been formed (for example by electrodeposition) on the
exposed areas of substrate 228 and first material 232. In FIG. 41I,
patternable mold material 234 has been removed (for example, by use
of a chemical stripper), leaving a cavity 223. In FIG. 41J,
materials 232 and 236 have been planarized to a sufficient depth to
remove all of second material 236 overlying first material 232, and
also to establish a layer of the desired thickness, flatness, and
surface finish. In FIG. 41K, object 238 has been placed inside
cavity 223.
[0365] Thus, it can be seen that according to the embodiment of the
invention described above, a cavity is created by patterning two
layers of patternable mold material. First, a layer of patternable
mold material is patterned for the deposit of the first material.
The first material is deposited. The first patternable mold
material is removed to form a cavity. Then, a second layer of
patternable mold material is formed and patterned for the deposit
of the second material. The second layer of patternable mold
material protects the cavity from deposition of the second
material. The second material is then deposited, and the second
layer of patternable mold material is removed. The object is then
placed in the cavity. Although the object is shown as being placed
into the cavity after the formation of a first layer according to
some embodiments of the invention, other embodiments may form
additional layers while maintaining the cavity. Once the desired
number of layers has been formed or at some intermediate point in
the formation of layers, the object may be inserted in the cavity.
According to some embodiments of the invention, additional material
may be deposited over the object to secure it in place; if desired
the layer may be planarized again after this deposition step.
According to some embodiments of the invention, first material 232
may be a sacrificial material while second material 236 may be a
structural material. In other embodiments, the reverse may also be
true. When first material 232 is the sacrificial material, etching
efficiency of the sacrificial material may be improved due to the
sacrificial material being adjacent to the cavity, thus allowing
the etchant to more easily gain access to the sacrificial material.
Indeed, the method shown in FIG. 4I can be used without the
addition of an object in order to create structures in which one or
more regions of sacrificial material contain a cavity to improve
etching. In addition, during a planarization step, it may be
advantageous to have the sacrificial material adjacent to the
structural material as shown in FIG. 41I, such that the structural
material may smear less on its corners.
[0366] According to further embodiments of the invention, as shown
in FIGS. 42A-42P, the patternable mold material may be used as the
sacrificial material in order to form channels or other hollow
shapes within layers formed on a substrate. As shown in FIG. 42A, a
substrate 240 is provided, onto which patternable mold material 242
(for example, photoresist or solder mask) has been deposited as
shown in FIG. 42B. In FIG. 42C, material 242 has been patterned
(for example, if a photoresist, by use of a photomask, developing,
etc., by laser direct imaging, a pattern generator and the like or,
a combination of these methods) to produce apertures 225 and 227
and patternable mold material portions 242(a) and 242(b). In FIG.
42D, a structural material 244 (for example, a metal such as gold)
has been formed (for example by electrodeposition) in apertures
225, 227. According to some embodiments, planarization may then be
performed, if necessary, as shown in FIG. 42E. In FIG. 42F, a
second layer of patternable mold material 246 has been formed over
patternable mold material 242 and structural material 244 and
patterned as shown in FIG. 42G. In FIG. 42H, another layer of
structural material 244 has been formed over the first layer of
structural material 244, by, for example, electrodeposition.
[0367] It can be seen in FIG. 42H that the second layer of
structural material 244 is formed over the first layer of
structural material 244. Structural material 244 also mushrooms
over onto the narrow portion 242(a) of patternable mold material
from both sides (as indicated by reference number 229 in FIG. 42H)
such that portion 242(a) is completely covered by structural
material 244. The dimensions of the patternable mold material 246
that has been patterned to remain over wide portion 242(b), as
shown in FIG. 42H, may be chosen such as to fill a space that it
has been predetermined will approximately exist as a result of the
mushrooming of structural material 244 over the wide portion
242(b). The amount of mushrooming that may occur for a given
deposited material may be determined based on factors such as, for
example, the thickness of the deposited material, the type of
plating bath used, the amount of agitation within the plating bath
and other plating parameters. In FIG. 42I, planarization has been
performed.
[0368] In FIG. 42J, a third layer of patternable mold material 248
has been formed over the second layer of structural material 244
and patternable mold material 246. Patternable mold material 248 is
then patterned. In FIG. 42K, a third layer of structural material
244 has been formed over the second layer of structural material
244 and patternable mold material 246. Again, the dimensions of the
patternable mold material 248 that has been patterned to remain
over patternable mold material 246, as shown in FIG. 42K, may be
chosen such as to fill a space that it has been predetermined will
approximately exist as a result of the mushrooming of structural
material 244 over patternable mold material 246. In FIG. 42M,
planarization has again been performed.
[0369] In FIG. 42N, a fourth layer of structural material 244 has
been formed over the third layer of structural material 244 and
patternable mold material 248. The dimensions of the patternable
mold material 248 that has been patterned to remain over
patternable mold material 246 are now such that mushrooming of
structural material 244 from both sides (as indicated by reference
number 231 in FIG. 42N) completely covers patternable mold material
248. In FIG. 42O, planarization has again been performed. In FIG.
42P, the sacrificial patternable mold material has been removed,
leaving channels 250 and 252.
[0370] As described above, some embodiments of the invention
advantageously use a patternable mold material as the sacrificial
material to form structures with only the patternable mold material
and a structural material. In this manner, an additional metal
sacrificial material is not required to build structures. In
addition, structures that might be difficult to etch using a metal
sacrificial material are possible when using a patternable mold
material as the sacrificial material, according to some embodiments
of the invention as described above. For example, if the
patternable mold material is a polymer material, etching may be
performed using plasma, which penetrates into narrow cavities more
easily than a liquid etchant can. According to some embodiments of
the invention, structural material 244 may be the same material on
each layer or may be two or more different materials. According to
some embodiments of the invention, software may be used to
automatically modify the original geometry so as to allow
structures to be fabricated using a patternable mold material as
the sacrificial material. For example, the channel on the right
side of FIG. 42P may have been originally designed with a
rectangular shape similar to the channel on the right, but wider.
In this case the software--having been provided with information
about the maximum width of mold material that may be bridged by
mushrooming structural material (as a function of various
parameters)--may have modified the rectangular geometry to yield
the domed geometry shown in FIG. 42P to enable fabrication.
[0371] FIGS. 43A-43R show an alternative embodiment for using
patternable mold material as the sacrificial material. As shown in
FIG. 43A, a substrate 254 is shown, onto which patternable mold
material 256 (for example, photoresist or solder mask) has been
deposited as shown in FIG. 43B. In FIG. 43C, material 256 has been
patterned (for example, if a photoresist, by use of a photomask,
developing, etc., by laser direct imaging, a pattern generator and
the like or, a combination of these methods) to produce apertures
233 and 235. In FIG. 43D, a material 258 (for example, a metal such
as copper) has been formed (for example by electrodeposition) in
apertures 233, 235. In FIG. 43E, planarization has been
performed.
[0372] In FIG. 43F, in order to make the top surface of the
patternable mold material 256 conductive, a coating of fine
particles 260 are applied to the top surface of patternable mold
material 256. According to some embodiments of the invention, the
particles 260 may be applied as a slurry within a liquid carrier
such as, but not limited to, alcohol. The carrier then evaporates,
leaving behind the particles 260. According to alternative
embodiments, the particles 260 may be airborne particles that are
"dusted" onto the surface of material 258 and patternable mold
material 256. According to further alternative embodiments, the
particles 260 may be applied onto the surface of material 258 and
patternable mold material 256 using an electrostatic attraction.
Particles 260 are chosen such that they do not adhere strongly to
the surface of the material 258 and may easily be washed away or
otherwise removed. In one embodiment, particles 260 may be, for
example, copper particles.
[0373] In FIG. 43G, patternable mold material 256 has been made
softer and/or tackier by, for example, heating and/or through the
use of a suitable solvent in order to secure the particles 260
using the patternable mold material 256. If heating is used, it may
be done in an oven, for example, or may be done using infrared
light or other suitable method of heating. In some embodiments, in
addition, or in the alternative, pressure may be applied (for
example, with a conformable pad) to the particles 260 in order to
push them into the patternable mold material 256. According to
still further embodiments, a patternable mold material may be used
that has selectively tacky areas for receiving the particles and
other areas that are not tacky and will not receive the
particles.
[0374] Then, as shown in FIG. 43H, a removal process (e.g., a
rinse, application of a stream of air and the like) has been
performed to remove the particles 260 that are above the material
258, such that the particles 260 remain only over the patternable
mold material 256 which was softened and made tackier by the
process described above to receive and secure them. According to
some embodiments of the invention, the particles may be washed away
using, for example, alcohol or other suitable material.
[0375] The particles 260 may be applied close enough together that
they form a continuous conductive film over patternable mold
material 256 and material 258. In other embodiments, after
application of the particles 260, they may be consolidated by
melting during, for example, a heating step. The heating step may
be a heating step as described above for softening patternable mold
material 256.
[0376] As a result, as shown in FIG. 43H, assuming material 258 is
conductive (for example, a metal), a completely conductive surface
now exists due to the linking together of portions of material 258
by conductive particles 260. Thus, a plating base exists for
plating of a subsequent layer. In some embodiments, small gaps
between the particles 260 may be acceptable in forming a plating
base, as bridging of material 258 may occur across the gaps between
individual particles 260. In FIG. 43I, a second layer of
patternable mold material 262 has been formed over material 258 and
particles 260. In FIG. 43J, patternable mold material 262 has been
patterned to form apertures 237, 239 and 241. In FIG. 43K, a second
layer of material 258 has been deposited into apertures 237, 239
and 241. In FIG. 43L, planarization may be performed, if
necessary.
[0377] In FIG. 43M, a second layer of particles 260 are applied to
the top surface of the second layer of material 258 and patternable
mold material 262 to form a conductive plating base, as described
above. In FIG. 43N, the particles 260 have been secured to
patternable mold material 256, as described above. In FIG. 43E, a
removal process has been performed to remove particles 260 that are
above the material 258, such that the particles 260 remain only
over the patternable mold material 262. In FIG. 43P, a third layer
of patternable mold material 264 and a third layer of material 258
have been formed in the same manner as that described above.
Additional layers may be formed in the same manner if desired.
[0378] In FIG. 43Q, patternable mold material 256, 262 and 264 has
been removed. According to some embodiments of the invention,
particles 260 may also be a sacrificial material (i.e., may be
removed to form a final structure). In that case, particles 260 may
be removed using an additional removal step suitable to the
material used to form particles 260. As shown in FIG. 43Q,
particles 260 may be removed by, for example, a liquid etchant. The
liquid etchant may easily access and remove the particles 260 due
to the open channels that are formed by the removal of the
patternable mold material. In FIG. 43R, an exemplary final
structure formed from material 258 is shown. According to some
embodiments of the invention, material 258 may be the same material
on each layer or may be two or more different materials. In
addition, in some embodiments, it may be desirable to leave
particles 260 in the final structure such that the final structure
would be as shown in FIG. 43Q.
[0379] According to some alternative embodiments of the invention,
instead of applying particles 260 in the step shown in FIG. 43F,
the particles 260 may be applied to exposed areas of patternable
mold material 256 after the second layer of patternable mold
material 262 is formed and patterned as shown in FIG. 43J. The
particles 260 may then be secured in the patternable mold material
256 using a process as described above.
[0380] According to other alternative embodiments of the invention,
a patternable mold material may be used to form a pattern for the
deposition of a material such as material 258. After material 258
has been deposited, the patternable mold material may then be
removed and replaced with a tacky material that is suitable for
receiving particles 260 without an additional heating step or the
use of a solvent. According to further alternative embodiments, a
patternable mold material may be used to form a pattern for the
deposition of a material such as material 258. The patternable mold
material may then be removed and replaced with a conductive
material other than a metal to form a continuous plating base with
the deposited material. Such a non-metal conductive material (for
example, a conductive polymer such as a conductive epoxy) may have
the advantage of being more easily removable than a metal.
Particles 260 are preferably small to minimize any potential
roughness (as indicated in FIG. 43R on surfaces facing substrate
254.
[0381] FIGS. 44A-44I show another alternative embodiment for using
patternable mold material as the sacrificial material. As shown in
FIG. 44A, a substrate 266 is shown, onto which patternable mold
material 268 (for example, photoresist or solder mask) has been
deposited as shown in FIG. 43B. Patternable mold material 268 may
be applied, for example, using a spin-on process, using a curtain
coater or any other suitable method to apply the patternable mold
material. Patternable mold material 268 comprises conductive
particles 270 that are initially dispersed at a low density
throughout the patternable mold material 268. The low density
dispersion of particles 270 allows light to be passed through the
patternable mold material 268 so that it may be patterned to form
apertures 243 and 245 without significant interference from
particles 270, as shown in FIG. 44C.
[0382] In FIG. 44D, material 272 has been formed in apertures 243
and 245. In FIG. 44E, power supply provides an electric field for
driving particles 270 to the upper surface of patternable mold
material 268 to form a plating surface for a subsequent layer of
material 272. An electrode having one polarity is positioned above
an upper surface of patternable mold material 268 and substrate 266
serves as an electrode of opposite polarity such that a resulting
electric field drives the conductive particles 270 to the upper
surface of the patternable mold material 268.
[0383] Other alternative methods for driving particles 270 to the
upper surface of patternable mold material 268 include, but are not
limited to, applying a magnetic field to magnetically attract the
particles 270 to the upper surface of patternable mold material
268; applying a centrifugal force to induce the particles 270 to
migrate to the upper surface of patternable mold material 268;
lowering a viscosity of the patternable mold material 268 such that
the particles migrate (e.g., if buoyant) to the upper surface of
patternable mold material 268; and vibrating the substrate 266 and
patternable mold material 268 such that the particles 270 to
migrate to the upper surface of patternable mold material 268; or
any combination of the above.
[0384] According to some alternative embodiments of the invention,
the driving of the particles 270 the upper surface of the
patternable mold material may be performed at times in the process
other than as has been already described. For example, the driving
step may be performed at some point after the patternable mold
material 268 has been patterned, as shown in FIG. 44C, but before
the second layer of material 272 is deposited, as shown in FIG.
44H. According to some embodiments of the invention, material 272
may be the same material on each layer or may be two or more
different materials.
[0385] In FIG. 44F, after the particles 270 have been positioned
along the upper surface of the patternable mold material 268 to
form a plating surface, a second layer of patternable mold material
278 has been formed and patterned to produce apertures 247 and 249,
as shown in FIG. 44G. In FIG. 44H, a second layer of material 272
has been formed in apertures 247, 249 and planarized if necessary.
In FIG. 44I, patternable mold material 268, 278 and particles 270
have been removed and a final structure formed from material 272
remains.
[0386] In other alternative embodiments, the patternable mold
material may be used as a sacrificial material along with two or
more structural materials or along with a second sacrificial
material. In still other embodiments, the patternable mold material
may be used as one of two or more structural materials with or
without a sacrificial material, or it may be used as a structural
material along with a sacrificial material (e.g. an
electrodeposited metal) that will be removed. In still other
embodiments seed layers may be applied in a variety of ways to the
patternable mold material to allow more geometric freedom in terms
of the structures that can be formed. Various alternative
techniques for applying and removing seed layer materials may be
found in U.S. patent application Ser. No. 10/841,300, filed May 7,
2004 (Microfabrica Docket No. P-US099-A-MF) referenced in the table
to follow and incorporated herein by reference. In some
embodiments, seed layers may be applied in a planar manner and as
necessary undesired portions may be removed after patterning a
desired material on the seed layer. In some embodiments seed layers
may be applied in a selective or blanket manner (e.g. a non-planar
manner) over an initially applied dielectric or conductive material
so it is only located on desired portions of a previously formed
layer and such that planarization operations may be used to remove
it from undesired regions (e.g. above the dielectric or previously
applied conductive material). In still other embodiments, a
combination of these approaches may appropriate.
[0387] FIGS. 45A-45M show an embodiment of the invention for
building layers on large substrates in such a manner as to minimize
stresses to a large substrate that may result from deposited
materials (which may be exhibit residual stress) deforming the
substrate, causing cracking of deposited materials, separation
between deposited materials, and so forth. Stresses due to thermal
expansion of deposited materials as a result of heating or cooling
the deposited materials and/or substrate (the deposited materials
may have different coefficients of thermal expansion) can also be
minimized by some embodiments of the invention. In addition, some
embodiments of the invention may facilitate dicing of large
substrates into smaller pieces.
[0388] According to exemplary EFAB processes, a selective
deposition of a first material is performed. Then a blanket
deposition of a second material is performed. Thus, if a wafer
including many devices is being fabricated, the devices are usually
constructed of a structural material confined to particular dies on
the wafer. Sacrificial material would then be blanket deposited
everywhere else on the wafer. This `ocean` of sacrificial material
may mechanically couple together all the devices. Any stresses that
may be associated with the sacrificial or structural material may
thus be disadvantageously coupled across the entire wafer and may
cause, for example, cracking of the deposited materials and/or
distortion (such as bowing) of the wafer.
[0389] In order to minimize such problems, some embodiments of the
invention restrict the area where the sacrificial material is
deposited by forming regions free of sacrificial material during
the fabrication process and doing a second pattern deposit of the
material rather than a blanket deposit. In this manner, the
sacrificial material is only placed where it is needed and any
cracking, bowing or other distortion of the wafer is minimized.
These regions may correspond to the dicing lanes between individual
die, as is assumed in the description shown in FIG. 45, or may be
formed in any other pattern as required.
[0390] As shown in FIG. 45A, a substrate 280 is shown, onto which
patternable mold material 282 (for example, photoresist or solder
mask) has been deposited as shown in FIG. 45B. In FIG. 45C,
material 282 has been patterned (for example, if a photoresist, by
use of a photomask, developing, etc., by laser direct imaging, a
pattern generator and the like or, a combination of these methods)
to produce apertures 251, 253, 255, 257, 259 and 261 between
portions of patternable mold material 282(a) and 282(b) that will
later be removed to form dicing lanes. Apertures 251 and 253 belong
to a first die on the substrate. Apertures 255 and 257 belong to a
second die on the substrate. Apertures 259 and 261 belong to a
third die on the substrate. In FIG. 45D, a first material 284 (for
example, a metal such as nickel) has been selectively formed (for
example by electrodeposition) in apertures 251, 253, 255, 257, 259
and 261 and planarization, if necessary, has been performed.
[0391] In FIG. 45E, patternable mold material 282 has been removed
and dicing lanes 263 and 265 are formed. In FIG. 45F, a second
layer of patternable mold material 286 has been deposited over
material 282. Patternable mold material 286 may be, for example, a
dry film resist, a liquid resist, or any other suitable patternable
mold material. In FIG. 45G, patternable mold material 286 has been
patterned to form protective barriers over dicing lanes 263 and 265
that are located between the three dies. A dry film resist may tent
over apertures 255 and 257, as shown in FIG. 45G. If a liquid or
electrodeposited resist is used, it may fill apertures 255 and 257.
According to some embodiments of the invention In FIG. 45H, a
second material 288 has been deposited over exposed portions of
first material 284 and substrate 280. In FIG. 45I, patternable mold
material 286 has been removed. In FIG. 45J, planarization has been
performed. It can be seen in FIG. 45J that dicing lanes 263, 265
are not filled with second material 288.
[0392] According to some alternative embodiments of the invention,
patternable mold material 286 may be removed during the
planarization step rather than in a separate step. Where a liquid
resist is used, a portion of the resist left in apertures 255 and
257 after planarization may remain during the build process (though
it may ultimately be removed). The patternable mold material
filling apertures 255 and 257 may be beneficial during the
planarization process for, as an example, minimizing smearing of
the metals.
[0393] In FIG. 45K, three layers of first material 284 and second
material 288 have been built on substrate 280 in the manner
described above. In FIG. 45L, dicing of substrate 280 has been
performed. It can be seen from FIG. 45L that the dicing may be
performed without having to cut through the first and second
materials. This may be beneficial in that deposited metals have a
tendency to negatively affect tools such as dicing saws that are
used to perform the dicing (e.g., clogging the saw blade due to
their relative softness), whereas the substrate may not do so. In
FIG. 45M, the first material 284 has been removed, leaving a
structure formed from the second material 288.
[0394] Thus, it can be seen that some embodiments of the invention
as described above may minimize deleterious effects such as
cracking and distortion. Because the dicing lanes of the substrate
do not receive the second material when it is deposited, individual
dies are de-coupled from each other and stresses on the substrate
are minimized. According to some alternative embodiments of the
invention, if the die layout of a particular substrate is known a
generic mask (such as a conformable contact mask) for masking out
the dicing lanes may be used to prevent deposition into the dicing
lanes.
[0395] Arrays of structures are often fabricated to fulfill a
particular function. For example, an array of probe tips may be
desirable for probing a wafer. As a result, a set of photomasks may
be created to pattern a first array of probes on a first wafer
having particular devices at particular locations on the first
wafer. If a second wafer has devices located at different locations
than the first wafer, it may be necessary to create a new set of
photomasks for patterning a new array of probes suitable for the
second wafer. Thus, it may be required to create a new set of
photomasks for patterning an array of devices such as probes each
time the layout of the probes changes.
[0396] FIGS. 46A-46Q show an embodiment of the invention for
fabricating customized arrays of devices without needing to use an
entirely new set of photomasks for each customized array
configuration. Instead, according to some embodiments of the
invention, a first set of photomasks may be used to create a full
array of structures that may be used with many different device
layouts. Depending on a particular device layout, a second
photomask may be used to select particular ones of the structures
in the full array that will be removed from the full array in order
to form a "customized array". According to some embodiments of the
invention, the structures selected for removal from the full array
may be removed during the fabrication process by creating a
delamination condition for the selected structures. In this manner,
rather than creating a new set of photomasks having a new desired
array of structures, only one new photomask is required.
[0397] As shown in FIG. 46A, a substrate 290 is shown, onto which
positive patternable mold material 292 (for example, a positive
photoresist) has been deposited as shown in FIG. 46B. In FIG. 46C,
photomask 294 is used to expose patternable mold material 292 in a
manner that would pattern a full array of five sets of portions of
the patternable mold material that would be used to form five
devices if no additional exposures of the patternable mold material
292 were to occur (See FIG. 46E). The number of devices has been
arbitrarily chosen to be five for simplicity. Some embodiments of
the invention are also applicable to arrays having different
numbers of devices.
[0398] According to some embodiments of the invention, in FIG. 46D,
a second photomask 296 is used to again expose patternable mold
material 292 such that two of the five sets of portions of the
patternable mold material that would result from the first exposure
with photomask 294 will not be formed. (According to other
embodiments, the sequence of exposure by the first and second
photomasks may be reversed.) In FIG. 46E, the pattern of the array
of devices is shown. It can be seen in FIG. 46E that only three of
the five sets of portions of the patternable mold material have
been patterned. Two of the sets (shown by phantom lines) have not
been patterned as a result of the second exposure of the
patternable mold material 292 using photomask 296. In FIG. 46F,
first material 298 (for example, nickel) has been formed in
apertures resulting from the patterning of patternable mold
material 292. In FIG. 46G, patternable mold material 292 has been
removed. In FIG. 46H, a second material 302 (for example, copper)
has been blanket deposited over exposed portions of substrate 290
and first material 298. In FIG. 46I, planarization has been
performed.
[0399] In FIG. 46J, a second layer of positive patternable mold
material 304 is formed over first material 298 and second material
302. As shown in FIG. 46K, photomask 306 is used to pattern
patternable mold material 304 in order to form an array of five
devices. According to the exemplary embodiment, a second masking
step is not performed on the second layer of devices, as was done
on the first layer. However, according to other embodiments such a
second masking step may be performed with a custom photomask if
desired. In FIG. 46L, a second layer of first material 298 has been
formed in the apertures that have been patterned in patternable
mold material 304 and a planarization step has been performed if
necessary. In FIG. 46M, patternable mold material 304 has been
removed. In FIG. 46N, a second layer of second material 302 has
been formed and planarization has been performed. In FIG. 46O, two
additional layers of first material 298 and second material 302
have been formed in the same manner.
[0400] In FIG. 46P, first material 298 has been removed, including
portions on which the two devices patterned for removal during the
second exposure step (shown in FIG. 46D) have been formed. Because
the portions of first material 298 supporting these two devices are
removed, the devices themselves will also be separated from
substrate 290, as shown. In FIG. 46Q, an array of devices having a
selected configuration has been formed.
[0401] FIGS. 47A-47J show another embodiment of the invention for
fabricating customized arrays of devices without needing to use a
different set of photomasks for each customized array
configuration. The embodiment described below differs from the
embodiment previously described in that a negative patternable mold
material is used rather than a positive patternable mold material.
Also, in the embodiment described below the structural material is
deposited first and the sacrificial material is deposited second,
whereas the reverse was true for the previously described
embodiment.
[0402] As shown in FIG. 47A, a substrate 308 is shown, onto which a
negative patternable mold material 310 (for example, a negative
photoresist) has been deposited as shown in FIG. 47B. In FIG. 47C,
photomask 312 is used to expose patternable mold material 310 to
form sets of apertures for forming a full array of five devices.
Again, some embodiments of the invention are applicable to arrays
having any number of devices. In FIG. 47D, a second photomask 314
is used to again expose patternable mold material 310 such that two
of the sets of apertures (shown by phantom lines in FIG. 47E) will
not be formed. In FIG. 47F, a first material 316 (e.g., nickel) has
been formed in the apertures patterned in patternable mold material
310 and planarization has been performed if necessary. In FIG. 47G,
patternable mold material 310 has been removed. In FIG. 47H, a
second material 318 (e.g., copper) has been blanket deposited over
exposed portions of substrate 308 and first material 316. In FIG.
47I, planarization has been performed. In FIG. 47J, a second layer
of negative patternable mold material 320 has been deposited. As
shown in FIG. 47K, photomask 322 is used to pattern patternable
mold material 320 in order to form an array of five devices.
According to the exemplary embodiment, a second masking step is not
performed on the second layer of devices, as was done on the first
layer. However, according to other embodiments such a second
masking step may be performed with a custom photomask if desired.
In FIG. 47L, a second layer of first material 316 has been formed
in the apertures that have been patterned in patternable mold
material 320 and a planarization step has been performed if
necessary. In FIG. 47M, patternable mold material 320 has been
removed. In FIG. 47N, a second layer of second material 318 has
been formed and planarization has been performed. In FIG. 47O, two
additional layers of first material 316 and second material 318
have been formed in the same manner.
[0403] In FIG. 47P, second material 318 has been removed, including
portions on which the two devices patterned for removal during the
second exposure step (shown in FIG. 47D) have been formed. Because
the portions of second material 318 supporting these two devices
are removed, the devices themselves will also be separated from
substrate 290, as shown. In FIG. 47Q, an array of devices having a
selected configuration has been formed.
[0404] Thus, according to some embodiments of the invention, a
first set of photomasks is used to fabricate a full array of
structures. A second photomask is then used to selectively remove
particular ones of the structures from the full array by creating a
delamination condition for the selected structures by forming the
selected structures on a sacrificial material that will be removed
from the substrate. When the sacrificial material is removed, the
selected structures are removed from the full array of
structures.
[0405] According to some alternative embodiments of the invention,
rather than double exposing the patternable mold material, a
simultaneous exposure may be performed in which one or more
photomasks of the set used to fabricate a full array of structures
is exposed in series with a second photomask. In this case, the two
masks may be aligned to each other as well as to the substrate. To
do this, one mask may be put into the mask aligner (not shown) as
is normally done. The other mask may then be put onto the substrate
chuck (not shown) in order to align the two masks with one another.
The two masks may be put in contact with one another and then
clamped in the mask aligner. According to yet other alternative
embodiments of the invention, in lieu of a double exposure or
simultaneous exposure using two photomasks to pattern the mold
material for a given layer of a group of structures, a single
customized photomask may be used to pattern a patternable mold
material wherein the single photomask is used to pattern only the
desired configuration of devices, again creating a delamination
condition for selected structures.
[0406] FIG. 48A shows a substrate 324 on which a structural
material 326 and a sacrificial material 328 have been formed. As
shown in FIG. 48B, when the sacrificial material 328 is removed,
the remaining structural material 326 forms structures having a
certain length l. According to some embodiments of the invention
described above for fabricating customized arrays of devices, an
interruption at a particular length in selected ones of the
structures may be brought about through the use of the methods
described above for creating customized arrays of devices.
[0407] FIG. 49A shows a substrate 324 on which a structural
material 326 and a sacrificial material 328 have been formed.
According to some embodiments of the invention, interruptions are
formed in the structural material using one or more of the methods
described above for creating customized arrays of devices. As shown
in FIG. 49A, a first group of interruptions 267 is formed by
patterning a first layer using either double exposure with two
masks, simultaneous exposure with two masks, or a single mask
customized for the layer, as described above. Then a second group
of interruptions 269 is formed by patterning a second layer using
one of the methods described above. Finally, a third group of
interruptions 271 is formed by patterning a third layer using one
of the methods described above. In FIG. 49B, sacrificial material
328 has been removed, leaving behind structures of material 326
having varying lengths.
[0408] According to the embodiment of the invention shown in FIGS.
49A-49B, the portions of the structures that are removed may be
discarded if attachment to a substrate is required for usability.
According to an alternative embodiment shown in FIGS. 50A-50D, the
portions removed may be preserved. FIG. 5OA shows a substrate 324
on which a structural material 326 and a sacrificial material 328
have been formed. Interruptions are formed in the structural
material using one or more of the methods described above for
creating customized arrays of devices. As shown in FIG. 5OA, a
first group of interruptions 273 is formed by patterning a first
layer using either double exposure with two masks, simultaneous
exposure with two masks, or a single mask customized for the layer,
as described above. Then a second group of interruptions 275 is
formed by patterning a second layer using one of the methods
described above.
[0409] In FIG. 5OB, a second substrate 330 is added on a side of
the build of layers opposite from the substrate 324 before
sacrificial material 328 is removed. In FIG. 5OC, substrate 324 is
shown after removal of sacrificial material 328 and has structures
of varying length. In FIG. 5OD, substrate 330 is shown after
removal of sacrificial material 328 and has structures of varying
length. The structures on substrate 330 are complementary to those
on substrate 324.
[0410] According to some embodiments of the invention shown in
FIGS. 51A-51B, a tie may be formed in the structural material to
hold together the portions of the structural material that are
removed. FIG. 51A shows a substrate 332 on which a structural
material 326 and a sacrificial material 328 have been formed.
According to some embodiments of the invention, a tie 334 is formed
in at least one layer (e.g., a final layer as shown here) of the
build of layers such that when the sacrificial material 328 is
removed as shown in FIG. 51B, the tie 334 holds together what would
have otherwise been individual portions of the structural material
326. This may be advantageous in preventing individual portions of
the removed structural material 326 from becoming tangled with
portions remaining on substrate 332 during the process for removing
the sacrificial material 328. A chuck such as a vacuum chuck or a
magnetic chuck may be attached to the tie 334 either before or
after removal of sacrificial material 328 in order to pull away the
removed structural material 326.
[0411] FIGS. 52A-52G show an embodiment of the invention for
pre-patterning a patternable mold material on a temporary substrate
before using the temporary substrate to form a pattern for
depositing other materials on a separate substrate. FIG. 52A shows
temporary substrate 336. Patternable mold material 338 is formed on
temporary substrate 336, as shown in FIG. 52B. In FIG. 52C,
patternable mold material 338 has been patterned. In FIG. 52D,
temporary substrate 336 and patternable mold material 338 have been
turned over and bonded (for example, by adhesion or re-lamination)
to a separate substrate 340. In FIG. 52E, temporary substrate 336
has been removed (e.g., by peeling off or dissolving). In FIG. 52F,
material 342 is formed in apertures resulting from the patterning
of patternable mold material 338. In FIG. 52G, patternable mold
material 338 has been removed.
[0412] Thus, according to the above-described embodiment, a pattern
may be transferred from a temporary substrate to a substrate on
which layers will be built by temporarily bonding a patternable
mold material to the temporary substrate and then bonding the
patternable mold material to the build substrate and removing the
temporary substrate. According to some embodiments of the
invention, the patternable mold material may be a dry film resist
that will mechanically interlock with and/or chemically bond with a
surface of the temporary substrate and the build substrate. The
temporary substrate may be chosen such that it does not have good
adhesion properties with respect to the patternable mold material
used. The temporary substrate may be, for example, Teflon.RTM.,
SYTOP.RTM. or polypropylene or may be a sacrificial material that
may be dissolved. According to embodiments wherein the patternable
mold material is a dry film resist, the backing material of the dry
film resist may be adhered to the temporary substrate or may serve
as the temporary substrate while the dry film resist is exposed and
developed. Then, the backing may be removed, along with any
additional temporary substrate used.
[0413] FIGS. 53A-53F show another embodiment of the invention for
transferring a pattern from a temporary substrate to a build
substrate. FIG. 53A shows temporary substrate 344. Temporary
substrate 344 is a permeable substrate. Patternable mold material
346 is formed on temporary substrate 344, as shown in FIG. 53B. In
FIG. 53C, patternable mold material 346 has been patterned. In FIG.
53D, temporary substrate 344 and patternable mold material 346 have
been turned over and bonded (for example, by adhesion or
re-lamination) to a build substrate 348. In FIG. 53E, material 350
has been formed through permeable temporary substrate 344 in
apertures resulting from the patterning of patternable mold
material 346. As shown in FIG. 53E, according to some embodiments,
material 350 may not completely fill the apertures in order to
avoid welding the material 350 to the temporary substrate 344. In
FIG. 53F, temporary substrate 344 has been removed by dissolving or
otherwise removing patternable mold material 346. The patternable
mold material 346 may be removed, for example, by a stripper that
passes through the permeable temporary substrate 344.
[0414] FIGS. 54A-54F show another embodiment of the invention for
transferring a pattern from a temporary substrate to a build
substrate. FIG. 54A shows temporary substrate 352. Temporary
substrate 352 may be a sacrificial anode formed from, for example,
solid copper, or may have a coating of material such as copper.
Patternable mold material 354 is formed on temporary substrate 352,
as shown in FIG. 54B. In FIG. 54C, patternable mold material 354
has been patterned. In FIG. 54D, temporary substrate 352 and
patternable mold material 354 have been turned over and bonded (for
example, by adhesion or re-lamination) to a build substrate
356.
[0415] In FIG. 54E, material 358 has been formed in apertures
resulting from the patterning of patternable mold material 354
during a plating step wherein the temporary substrate 352 and build
substrate 356 may be immersed in an electrodeposition tank (not
shown) during a plating step. Material 358 is formed from the
erosion of temporary substrate 352 during the plating step, as
shown in FIG. 54E. In FIG. 54F, temporary substrate 352 has been
removed after the plating step by removing patternable mold
material 354. The patternable mold material 354 may be dissolved,
for example, by a stripper applied to the sides of the build.
According to alternative embodiments, temporary substrate 352 may
be removed during a planarization step.
[0416] FIGS. 55A-55I show an embodiment of the invention for
depositing more than one material in an aperture formed in a
patternable mold material such that a layered deposit of materials
are formed on a single layer.
[0417] As shown in FIG. 55A, a substrate 360 is shown, onto which
patternable mold material 362 (for example, photoresist or solder
mask) has been deposited as shown in FIG. 55B. In FIG. 55C,
material 362 has been patterned (for example, if a photoresist, by
use of a photomask, developing, etc., by laser direct imaging, a
pattern generator and the like or, a combination of these methods)
to produce apertures. In FIG. 55D, a first material 364 is formed
in the apertures resulting from the patterning step. In FIG. 55E, a
second material 368 is formed in the apertures over the first
material 364. In FIG. 55F, patternable mold material 362 has been
removed. In FIG. 55G, third material 366 is blanket deposited over
exposed areas of substrate 360, first material 364 and second
material 368. In FIG. 55H, planarization has been performed.
[0418] According to some embodiments of the invention, first
material 364 may be a soft material (for example, tin), while
second material 368 may be a material that is harder than first
material 364 (for example, nickel). In this manner, some
embodiments of the invention allow a planarization step to be
performed such that the second material 368 is planarized until
just before the first material 364 is reached, as shown in FIG.
55H. This advantageously allows the use of a softer material as the
first material. The softer material will not be subjected to the
rigors of planarization (which may lead to excessive smearing of
the softer material, inclusions of abrasive, etc.) because it is
coated with a harder material such that the harder material is
planarized and not the softer material. After planarization, an
etching step, for example, may be used to remove the remainder of
the harder material, as shown in FIG. 55I, leaving the softer
material unexposed to planarization.
[0419] Although two materials are shown as being formed in the
apertures in FIG. 55E, some embodiments of the invention are
equally applicable to forming any number of materials in the
apertures before the patternable mold material is removed. Other
applications for some embodiments of the invention for depositing
more than one material in an aperture formed in a patternable mold
material include, but are not limited to, forming devices having a
superlattice of different materials, and forming alloys by using
heat to inter-diffuse multiple materials deposited one above the
above.
[0420] FIGS. 56A-56I show an alternative embodiment of the
invention for depositing more than one material in an aperture
formed in a patternable mold material such that a layered deposit
of materials are formed on a single layer. According to some
embodiments of the invention, a first material may be deposited
into an aperture and may have a top surface having a geometric
shape or particular composition or microstructure which it is
desirable to preserve during subsequent fabrication processes.
Thus, a second material may be deposited into the aperture to coat
the first material and preserve the shape or composition of the
first material during subsequent fabrication processes.
[0421] As shown in FIG. 56A, a substrate 370 is shown, onto which
patternable mold material 362 (for example, photoresist or solder
mask) has been deposited as shown in FIG. 56B. In FIG. 56C,
material 372 has been patterned (for example, if a photoresist, by
use of a photomask, developing, etc., by laser direct imaging, a
pattern generator and the like or, a combination of these methods)
to produce apertures. In FIG. 56D, a first material 374 is formed
in the apertures resulting from the patterning step. It is assumed
that first material 374 has a top surface that it is desirable to
preserve for some reason, for example, one of the reasons discussed
above. Therefore, in FIG. 56E, a second material 376 is formed in
the apertures over the first material 374. In FIG. 56F, patternable
mold material 372 has been removed. In FIG. 56G, third material 378
is blanket deposited over exposed areas of substrate 370, first
material 374 and second material 376. In FIG. 56H, planarization
has been performed. In FIG. 56I, second material 376 has been
removed, again exposing the first material 374 after the
planarization step.
[0422] FIGS. 57A-57G show an embodiment of the invention that uses
a patternable mold material to perform a patterned etch. FIG. 57A
shows three layers of two materials 384, 386 built on a substrate
380. The uppermost layer of the build is shown thicker than the
first two layers because planarization has not yet been performed
on the uppermost layer. In FIG. 57B, patternable mold material 382
has been formed over the uppermost layer of the build. In FIG. 57C,
patternable mold material 382 has been patterned to form apertures.
In FIG. 57D, the apertures are used for etching cavities into a
previously deposited material, which may be a sacrificial material
or a structural material. In FIG. 57E, the cavities are filled with
a third material 388. In FIG. 57F, patternable mold material 382
has been removed. In FIG. 57G, planarization has been performed, if
necessary.
[0423] Thus, some embodiments of the invention as described above
may be used to perform a patterned etch of an existing material on
a layer such that another material may be added to the layer. As
shown in FIGS. 57D-57E, the patternable mold material 382 may be
used both to etch the cavities and to define the deposition of the
third material 388, which minimizes the amount of third material
388 that must be removed during planarization. According to other
embodiments of the invention, patternable mold material 382 may be
removed after the etching step. If electrodeposition is used to
deposit the third material 388, any of the third material 388
formed above the upper level of the cavities may be removed in
during planarization.
[0424] FIGS. 58A-58J show an embodiment of the invention for using
a patternable mold material both to etch a pattern in a first
material and to plate a second material in the etched pattern.
[0425] As shown in FIG. 58A, a substrate 390 is shown, onto which a
first material 392 has been deposited as shown in FIG. 58B. In FIG.
58C, a patternable mold material 394 (for example a photoresist)
has been deposited. In FIG. 58D, material 394 has been patterned
(for example, if a photoresist, by use of a photomask, developing,
etc., by laser direct imaging, a pattern generator and the like or,
a combination of these methods) to produce apertures. In FIG. 58E,
the apertures are used to etch first material 392, as shown. In
FIG. 58F, a second material 396 is formed in the cavities that have
been etched in first material 392. Again, the patternable mold
material may be used both to etch the cavities and to define the
deposition of the third material so as to minimize the amount of
third material that must be removed during planarization. In FIG.
58G, patternable mold material 394 has been removed. In FIG. 58H,
planarization has been performed, if necessary.
[0426] It will be understood by those of skill in the art or will
be readily ascertainable by them that various additional operations
may be added to the processes set forth herein. For example,
between performances of the various deposition operations, the
various etching operations, and various planarization operations
cleaning operations, activation operations, and the like may be
desirable.
[0427] The patent applications and patents set forth below are
hereby incorporated by reference herein as if set forth in full.
The teachings in these incorporated applications can be combined
with the teachings of the instant application in many ways: For
example, enhanced methods of producing structures may be derived
from some combinations of teachings, enhanced structures may be
obtainable, enhanced apparatus may be derived, and the like.
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[0428] Various other embodiments exist. Some of these embodiments
may be based on a combination of the teachings herein with various
teachings incorporated herein by reference. Some embodiments may
not use any blanket deposition process and/or they may not use a
planarization process. Some embodiments may involve the selective
deposition of a plurality of different materials on a single layer
or on different layers. Some embodiments may use blanket
depositions processes that are not electrodeposition processes.
Some embodiments may use selective deposition processes on some
layers that are not even electrodeposition processes. Some
embodiments may use one or more structural materials (for example
nickel, gold, copper, or silver). Still other processes may use
other materials whether or not electrodepositable. Some processes
may use one or more sacrificial materials (for example copper).
Some embodiments may use copper as the structural material with or
without a sacrificial material. Some embodiments may remove a
sacrificial material while other embodiments may not. Some
embodiments may use conformable contact masks with different
patterns so as to deposit different selective patterns of material
on different layers and/or on different portions of a single
layer.
[0429] In view of the teachings herein, many further embodiments,
alternatives in design and uses are possible and will be apparent
to those of skill in the art. As such, it is not intended that the
invention be limited to the particular illustrative embodiments,
alternatives, and uses described above but instead that it be
solely limited by the claims presented hereafter.
* * * * *