U.S. patent application number 11/695593 was filed with the patent office on 2007-08-09 for cantilever microprobes for contacting electronic components and methods for making such probes.
This patent application is currently assigned to Microfabrica Inc.. Invention is credited to Christopher A. Bang, Richard T. Chen, Ezekiel J. J. Kruglick, Pavel B. Lembrikov, Dennis R. Smalley.
Application Number | 20070182427 11/695593 |
Document ID | / |
Family ID | 38284920 |
Filed Date | 2007-08-09 |
United States Patent
Application |
20070182427 |
Kind Code |
A1 |
Chen; Richard T. ; et
al. |
August 9, 2007 |
Cantilever Microprobes For Contacting Electronic Components and
Methods for Making Such Probes
Abstract
Embodiments disclosed herein are directed to compliant probe
structures for making temporary or permanent contact with
electronic circuits and the like. In particular, embodiments are
directed to various designs of cantilever-like probe structures.
Some embodiments are directed to methods for fabricating such
cantilever structures. In some embodiments, for example, cantilever
probes have extended base structures, slide in mounting structures,
multi-beam configurations, offset bonding locations to allow closer
positioning of adjacent probes, compliant elements with tensional
configurations, improved over travel, improved compliance, improved
scrubbing capability, and/or the like.
Inventors: |
Chen; Richard T.; (Burbank,
CA) ; Kruglick; Ezekiel J. J.; (San Diego, CA)
; Bang; Christopher A.; (San Diego, CA) ; Smalley;
Dennis R.; (Newhall, CA) ; Lembrikov; Pavel B.;
(Santa Monica, CA) |
Correspondence
Address: |
MICROFABRICA INC.;ATT: DENNIS R. SMALLEY
7911 HASKELL AVENUE
VAN NUYS
CA
91406
US
|
Assignee: |
Microfabrica Inc.
|
Family ID: |
38284920 |
Appl. No.: |
11/695593 |
Filed: |
April 2, 2007 |
Related U.S. Patent Documents
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Application
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Filing Date |
Patent Number |
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11028960 |
Jan 3, 2005 |
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11695593 |
Apr 2, 2007 |
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10949738 |
Sep 24, 2004 |
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11695593 |
Apr 2, 2007 |
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10772943 |
Feb 4, 2004 |
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10949738 |
Sep 24, 2004 |
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11029219 |
Jan 3, 2005 |
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11695593 |
Apr 2, 2007 |
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10949738 |
Sep 24, 2004 |
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11695593 |
Apr 2, 2007 |
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10772943 |
Feb 4, 2004 |
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10949738 |
Sep 24, 2004 |
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60582689 |
Jun 23, 2004 |
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60582690 |
Jun 23, 2004 |
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60609719 |
Sep 13, 2004 |
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60611789 |
Sep 20, 2004 |
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60540511 |
Jan 29, 2004 |
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60533933 |
Dec 31, 2003 |
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60536865 |
Jan 15, 2004 |
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60533947 |
Dec 31, 2003 |
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60445186 |
Feb 4, 2003 |
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60506015 |
Sep 24, 2003 |
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60533933 |
Dec 31, 2003 |
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60536865 |
Jan 15, 2004 |
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60582689 |
Jun 23, 2004 |
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60582690 |
Jun 23, 2004 |
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60609719 |
Sep 13, 2004 |
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60611789 |
Sep 20, 2004 |
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60540511 |
Jan 29, 2004 |
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60533933 |
Dec 31, 2003 |
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60536865 |
Jan 15, 2004 |
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60533947 |
Dec 31, 2003 |
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60445186 |
Feb 4, 2003 |
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60506015 |
Sep 24, 2003 |
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60533933 |
Dec 31, 2003 |
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60536865 |
Jan 15, 2004 |
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60536865 |
Jan 15, 2004 |
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60533933 |
Dec 31, 2003 |
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60506015 |
Sep 24, 2003 |
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Current U.S.
Class: |
324/755.07 |
Current CPC
Class: |
G01R 3/00 20130101; G01R
1/06738 20130101; G01R 31/2886 20130101; G01R 1/06744 20130101;
G01R 1/06755 20130101; C25D 5/02 20130101; G01R 1/07357 20130101;
G01R 1/0483 20130101; G01R 1/06727 20130101; G01R 1/06711 20130101;
G01R 1/06716 20130101; G01R 1/07342 20130101 |
Class at
Publication: |
324/751 |
International
Class: |
G01R 31/305 20060101
G01R031/305 |
Claims
1. A cantilever probe for making contact with an electronic circuit
element, comprising: at least one pivot element which is bonded to
a substrate; at least one beam element having a first distal end
and a second distal end, wherein the second distal end holds a
contact tip for making contact to an electronic circuit element,
and wherein the at least one beam element contacts the pivot
element at a location intermediate to the first and second distal
ends; a compliant element that functionally connects the substrate
to the beam element on a lateral side of the beam element that is
opposite to the lateral side of the beam, relative to the pivot
element, that holds the contact tip; wherein the compliant element
experiences a net tension force as the contact tip is pressed
against a target surface.
2. The cantilever probe of claim 1 wherein the tip of the probe is
formed from a different material than used in forming at least one
of the beams of the probe.
3. The cantilever probe of claim 1 wherein the beam portion narrows
with distance from the pivot element along at least a portion of
its length.
4. The cantilever probe of claim 1 wherein the pivot element has a
contact portion which has a curved shape whereby the contact region
between the pivot element and beam portion is reduced.
5. The cantilever probe of claim 1 wherein the pivot element has a
contact portion which has a pointed shape whereby the contact
region between the pivot element and beam portion is reduced.
6. The cantilever probe of claim 1 wherein the pivot element and
the beam portion are joined together in a manner that allows
rotation.
7. The cantilever probe of claim 1 wherein one of the pivot element
or the beam element includes at least one element that inhibits
lateral movement of the beam in a direction perpendicular to the
length of a beam portion that extends across the pivot.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
Nos. 11/028,960 and 11/029,219 which were both filed Jan. 3, 2005.
These two applications claim benefit of U.S. Application. Nos.
60/582,689; 60/582,690; 60/609,719; 60/611,789; 60/540,511;
60/533,933; 60/536,865; and 60/533,947 and are a
continuations-in-part of U.S. patent application Ser. No.
10/949,738 which in turn is a continuation-in-part of U.S. patent
application Ser. No. 10/772,943, which in turn claims benefit of
U.S. Application Nos. 60/445,186; 60/506,015; 60/533,933; and
60/536,865; furthermore the '738 application claims benefit of U.S.
Application Nos.: 60/506,015; 60/533,933; and 60/536,865. Each of
these applications is incorporated herein by reference as if set
forth in full herein including any appendices attached thereto.
FIELD OF THE INVENTION
[0002] Embodiments of the present invention relate to microprobes
(e.g. for use in the wafer level testing of integrated circuits,
such as memory or logic devices), and more particularly related to
cantilever microprobes. In some embodiments, microprobes are
fabricated using electrochemical fabrication methods (e.g.
EFAB.RTM. fabrication processes).
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 Inc. (formerly MEMGen.RTM. Corporation) of Burbank,
Calif. under the name EFAB.TM.. 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 Inc.
(formerly MEMGen.RTM. Corporation) of Burbank, Calif. such masks
have come to be known as INSTANT MASKS.TM. and the process known as
INSTANT MASKINGTM or INSTANT MASKTM 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. 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:
[0004] 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, August 1998.
[0005] 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. [0006] 3. A.
Cohen, "3-D Micromachining by Electrochemical Fabrication",
Micromachine Devices, March 1999. [0007] 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 MicroN\anotechnology for Space
Applications, The Aerospace Co., April 1999. [0008] 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. [0009] 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. [0010] 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.
[0011] 8. A. Cohen, "Electrochemical Fabrication (EFABTM)", Chapter
19 of The MEMS Handbook, edited by Mohamed Gad-El-Hak, CRC Press,
2002. [0012] 9. Microfabrication--Rapid Prototyping's Killer
Application", pages 1-5 of the Rapid Prototyping Report, CAD/CAM
Publishing, Inc., June 1999.
[0013] The disclosures of these nine publications are hereby
incorporated herein by reference as if set forth in full
herein.
[0014] 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: [0015] 1. Selectively depositing at
least one material by electrodeposition upon one or more desired
regions of a substrate. [0016] 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. [0017] 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.
[0018] 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.
[0019] 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.
[0020] 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.
[0021] 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.
[0022] 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.
[0023] 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 8 consisting of
a conformable or deformable (e.g. elastomeric) insulator 10
patterned on an anode 12. The anode has two functions. One is as a
supporting material for the patterned insulator 10 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.
FIG. 1A also depicts a substrate 6 separated from mask 8. CC mask
plating selectively deposits material 22 onto a substrate 6 by
simply pressing the insulator against the substrate then
electrodepositing material through apertures 26a and 26b in the
insulator as shown in FIG. 1B. After deposition, the CC mask is
separated, preferably non-destructively, from the substrate 6 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.
[0024] Another example of a CC mask and CC mask plating is shown in
FIGS. 1D-1G. FIG. 1D shows an anode 12' separated from a mask 8'
that includes a patterned conformable material 10' and a support
structure 20. FIG. 1D also depicts substrate 6 separated from the
mask 8'. FIG. 1E illustrates the mask 8' being brought into contact
with the substrate 6 . FIG. 1F illustrates the deposit 22' that
results from conducting a current from the anode 12' to the
substrate 6. FIG. 1G illustrates the deposit 22' on substrate 6
after separation from mask 8'. In this example, an appropriate
electrolyte is located between the substrate 6 and the anode 12'
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.
[0025] 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.
[0026] 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 2 which is
a sacrificial material and a second material 4 which is a
structural material. The CC mask 8, in this example, includes a
patterned conformable material (e.g. an elastomeric dielectric
material) 10 and a support 12 which is made from deposition
material 2. The conformal portion of the CC mask is pressed against
substrate 6 with a plating solution 14 located within the openings
16 in the conformable material 10. An electric current, from power
supply 18, is then passed through the plating solution 14 via (a)
support 12 which doubles as an anode and (b) substrate 6 which
doubles as a cathode. FIG. 2A, illustrates that the passing of
current causes material 2 within the plating solution and material
2 from the anode 12 to be selectively transferred to and plated on
the substrate 6. After electroplating the first deposition material
2 onto the substrate 6 using CC mask 8, the CC mask 8 is removed as
shown in FIG. 2B. FIG. 2C depicts the second deposition material 4
as having been blanket-deposited (i.e. non-selectively deposited)
over the previously deposited first deposition material 2 as well
as over the other portions of the substrate 6. 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 6. 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 20 formed of the second
material 4 (i.e. structural material) is embedded in first material
2 (i.e. sacrificial material) as shown in FIG. 2E. The embedded
structure is etched to yield the desired device, i.e. structure 20,
as shown in FIG. 2F.
[0027] Various components of an exemplary manual electrochemical
fabrication system 32 are shown in FIGS. 3A-3C. The system 32
consists of several subsystems 34, 36, 38, and 40. The substrate
holding subsystem 34 is depicted in the upper portions of each of
FIGS. 3A-3C and includes several components: (1) a carrier 48, (2)
a metal substrate 6 onto which the layers are deposited, and (3) a
linear slide 42 capable of moving the substrate 6 up and down
relative to the carrier 48 in response to drive force from actuator
44. Subsystem 34 also includes an indicator 46 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 34 further includes feet 68 for carrier
48 which can be precisely mounted on subsystem 36.
[0028] The CC mask subsystem 36 shown in the lower portion of FIG.
3A includes several components: (1) a CC mask 8 that is actually
made up of a number of CC masks (i.e. submasks) that share a common
support/anode 12, (2) precision X-stage 54, (3) precision Y-stage
56, (4) frame 72 on which the feet 68 of subsystem 34 can mount,
and (5) a tank 58 for containing the electrolyte 16. Subsystems 34
and 36 also include appropriate electrical connections (not shown)
for connecting to an appropriate power source (not shown) for
driving the CC masking process.
[0029] The blanket deposition subsystem 38 is shown in the lower
portion of FIG. 3B and includes several components: (1) an anode
62, (2) an electrolyte tank 64 for holding plating solution 66, and
(3) frame 74 on which feet 68 of subsystem 34 may sit. Subsystem 38
also includes appropriate electrical connections (not shown) for
connecting the anode to an appropriate power supply (not shown) for
driving the blanket deposition process.
[0030] The planarization subsystem 40 is shown in the lower portion
of FIG. 3C and includes a lapping plate 52 and associated motion
and control systems (not shown) for planarizing the
depositions.
[0031] 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.
[0032] Electrochemical fabrication provides the ability to form
prototypes and commercial quantities of miniature objects, parts,
structures, devices, and the like at reasonable costs and in
reasonable times. In fact, electrochemical fabrication is an
enabler for the formation of many structures that were hitherto
impossible to produce. Electrochemical fabrication opens the
spectrum for new designs and products in many industrial fields.
Even though electrochemical fabrication offers this new capability
and it is understood that electrochemical fabrication techniques
can be combined with designs and structures known within various
fields to produce new structures, certain uses for electrochemical
fabrication provide designs, structures, capabilities and/or
features not known or obvious in view of the state of the art.
[0033] A need exists in various fields for miniature devices having
improved characteristics, reduced fabrication times, reduced
fabrication costs, simplified fabrication processes, and/or more
independence between geometric configuration and the selected
fabrication process. A need also exists in the field of miniature
device fabrication for improved fabrication methods and
apparatus.
SUMMARY OF THE INVENTION
[0034] It is an object of some embodiments of the invention to
provide cantilever probes with improved characteristics.
[0035] It is an object of some embodiments of the invention to
provide cantilever probes that are more reliable.
[0036] It is an object some embodiments of the invention to provide
improved methods for fabricating cantilever probes.
[0037] Other objects and advantages of various embodiments of the
invention will be apparent to those of skill in the art upon review
of the teachings herein. The various embodiments of the invention,
set forth explicitly herein or otherwise ascertained from the
teachings herein, may address one or more of the above objects
alone or in combination, or alternatively may address some other
object of the invention ascertained from the teachings herein. It
is not necessarily intended that all objects be addressed by any
single aspect of the invention even though that may be the case
with regard to some aspects.
[0038] In a first aspect of the invention a cantilever probe for
making contact with an electronic circuit element, including: at
least one base element which is bonded to a substrate; a support
element which extends from a portion of the base element a
cantilever portion which has a proximal and distal end, wherein the
proximal end contacts the support element, and wherein a footprint
of the at least one base element underlies at least a portion of
the cantilever portion; and a tip portion which is located at or
near a distal end of the cantilever portion which may be used to
make electrical contact with a pad on an electronic circuit
element.
[0039] In a second aspect of the invention a cantilever probe for
making contact with an electronic circuit element, including: at
least one base element which is bonded to a substrate; a support
element which extends from the a portion of the base element a
cantilever portion which has a proximal and distal end, wherein the
proximal end contacts the support element, and wherein a footprint
of the at least one base element underlies at least 25% of the
cantilever portion; and a tip portion which is located at or near a
distal end of the cantilever portion which may be used to make
electrical contact with a pad.
[0040] In a third aspect of the invention a cantilever probe for
making contact with an electronic circuit element, including: at
least one base element which is bonded to a substrate; a support
element which extends from the a portion of the base element a
cantilever portion which has a proximal and distal end, wherein the
proximal end contacts the support element, and wherein a footprint
of the at least one base element underlies at least 50% of the
cantilever portion; and a tip portion which is located at or near a
distal end of the cantilever portion which may be used to make
electrical contact with a pad.
[0041] In a fourth aspect of the invention a cantilever probe for
making contact with an electronic circuit element, including: at
least one base element which is bonded to a substrate; a support
element which extends from the a portion of the base element a
cantilever portion which has a proximal and distal end, wherein the
proximal end contacts the support element, and wherein a footprint
of the at least one base element underlies at least 75% of the
cantilever portion; and a tip portion which is located at or near a
distal end of the cantilever portion which may be used to make
electrical contact with a pad.
[0042] In a fifth aspect of the invention an array of cantilever
probes for making contact with an electronic circuit element,
including a plurality of cantilever probes positioned relative to
each other wherein interlaced bonding locations are used on
adjacent probes.
[0043] In a sixth aspect of the invention a probe assembly for
making electric contact with an electronic circuit element,
including: a substrate including at least one structure; at least
one probe including: a contact tip portion; a compliant portion
functionally attached to the tip portion; and a base portion
functionally attached to the compliant portion, wherein the base
portion is configured to mate with and be at least partially
mechanically constrained by its physical configuration and the
physical configuration of the at least one structure on the
substrate.
[0044] In a seventh aspect of the invention a probe device for
testing integrated circuits, including: at least one post element;
a composite beam element, including at least two partially
independent beams attached to the at least one post element; and a
contact element attached to the composite beam element.
[0045] In an eighth aspect of the invention a probe device for
testing integrated circuits, including: at least one post element
having a first end connected to a substrate; a beam element
connecting the post element to a contact tip element; at least one
secondary beam element having one end connected to a contact tip
element and a second end; at least one bridge element connected to
the second end of the secondary beam structure; at least one
tertiary beam element having a first end connected to the bridging
element and having a second end; at least one secondary post
element connected to the substrate and to the tertiary beam.
[0046] In a ninth aspect of the invention a cantilever probe for
making contact with an electronic circuit element, including: at
least one pivot element which is bonded to a substrate; at least
one beam element having a contact tip attached thereto and
positioned to pivot about the pivot element; a compliant element
that functionally connects a substrate to the beam element on a
side of the beam that is opposite to that of the contact tip;
wherein the compliant element experiences a net tension force as
the contact tip is pressed against a target surface.
[0047] In a tenth aspect of the invention a cantilever probe for
making contact with an electronic circuit element, including: at
least one pivot element which is bonded to a substrate; at least
one beam element having a contact tip attached thereto and
positioned to pivot about the pivot element; a compliant element
that functionally connects a substrate to the beam element on a
same side of the beam which holds the contact tip; wherein the
compliant element experiences a net compressive force as the
contact tip is pressed against a target surface.
[0048] In an eleventh aspect of the invention a cantilever probe
for making contact with an electronic circuit element, including: a
support element; a cantilever portion which has a first and second
region, wherein the first region contacts the support element; and
a contact tip held by the cantilever portion at the second region,
wherein the cantilever portion has a shape which is narrower toward
the second region than the first region.
[0049] In a twelfth aspect of the invention a cantilever probe for
making contact with an electronic circuit element, including: at
least one base element which is bonded to a substrate; a support
element which extends from a portion of the base element a
cantilever portion which has a first region and a second region,
wherein the first region contacts the support element, and wherein
a footprint of the at least one base element underlies at least a
portion of the cantilever portion; and a tip portion which is held
by the cantilever portion at the second region which may be used to
make electrical contact with a pad on an electronic circuit
element.
[0050] In a thirteenth aspect of the invention a method for forming
a cantilever probe, including: (A) providing a build substrate; (B)
forming a plurality of deposited planarized layers of material on
the substrate according to a design of the cantilever probe; (C)
releasing the cantilever probe from any sacrificial material used
in forming the plurality of layers and from the build
substrate.
[0051] In a fourteenth aspect of the invention a method for forming
a cantilever probe, including: (A) providing a substrate; (B)
forming a plurality of deposited planarized layers of material on
the substrate according to a design of the cantilever probe; (C)
releasing the cantilever probe from any sacrificial material used
in forming the plurality of layers.
[0052] 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 apparatus and methods used in
implementing the above noted aspect of the invention. These other
aspects of the invention may provide various combinations of the
aspects, embodiments, and associated alternatives explicitly set
forth herein as well as provide other configurations, structures,
functional relationships, and processes that have not been
specifically set forth above.
BRIEF DESCRIPTION OF THE DRAWINGSi
[0053] FIGS. 1A-1C schematically depict side views of various
stages of a CC mask plating process, while FIGS. 1D-1G
schematically depict a side views of various stages of a CC mask
plating process using a different type of CC mask.
[0054] 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.
[0055] FIGS. 3A-3C schematically depict side views of various
example apparatus subassemblies that may be used in manually
implementing the electrochemical fabrication method depicted in
FIGS. 2A-2F.
[0056] FIGS. 4A-4F 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
[0057] FIG. 4G depicts the completion of formation of the first
layer resulting from planarizing the deposited materials to a
desired level.
[0058] FIGS. 4H and 4I respectively depict the state of the process
after formation of the multiple layers of the structure and after
release of the structure from the sacrificial material.
[0059] FIGS. 5A-5B depict side views of simplified examples of
cantilever probe structures.
[0060] FIGS. 6-17 depicts embodiments of cantilever structures have
enhanced base structures.
[0061] FIGS. 18A-18B depict a perspective view of an example
cantilever probe structure having an improved base structure
[0062] FIG. 19 depicts a top view of a probe array having seven
cantilever probes elements which form a linear contact pattern and
which have been spaced with a desired resolution by (1) having each
adjacent contact point accessed from opposite sides of the contact
line and by using bonding locations that are offset between
adjacent probes.
[0063] FIGS. 20A and 20B show perspective views from the top and
bottom, respectively, of a six probe array where all probes extend
from the same side of a contact line and where bonding region
interlacing is used to allow the probes to be located closer
together than would be allowed without the interlacing.
[0064] FIG. 21 shows a perspective view of two sets of six element
probe arrays that form two contact lines and which have the same
interlacing and bonding location compensation openings as noted
with regard to FIGS. 20A and 20B.
[0065] FIGS. 22A and 22B depict perspective and top views,
respectively, of probes and probe arrays that use different probe
designs and bonding regions for adjacent probes to allow tighter
pitching to be used.
[0066] FIGS. 23A-23C depict perspective views of cantilever
structures having base elements with "L" shaped structures that can
slide into and interlock with appropriate base structures affixed
to or forming part of a substrate.
[0067] FIG. 24A depicts a slotted mounting structure on a substrate
into which a probe with an "L" or "T" shaped base may be inserted
while FIG. 24B depicts a perspective view of such a probe slid into
the slotted mounting structure . . .
[0068] FIG. 25A depicts an alternative mounting structure
configuration while FIGS. 25B and 25 C depict two alternative
configurations for locating the mounting structures in forming
arrays of various pitch.
[0069] FIG. 26 depicts a perspective view of a plurality of probe
elements lying in a sideways orientation and stacked one above the
other as they may be formed according to some embodiments of the
invention.
[0070] FIG. 27 depicts a perspective view of an example of an
alternative embodiment where probe elements are separated from
other probe elements by shields.
[0071] FIGS. 28A-28C provide perspective views of an example of a
probe element having a protrusion on its base which may be slid
into retention structure on a substrate and locked in place by a
locking element.
[0072] FIGS. 29A-29B provide perspective views of example
multi-beam cantilever probes according to some embodiments of the
invention.
[0073] FIGS. 30A-30B provide perspective views of example
multi-beam cantilever probes having one or more bridging elements
that connect the otherwise independent beams together according to
some embodiments of the invention.
[0074] FIGS. 31 and 32 provide stress distribution plots for the
probes of FIGS. 30A and 30B respectively.
[0075] FIG. 33A provide an example of an alternative probe
configuration according to some embodiments of the invention where
the width of the beams are narrowed in the lower stress regions and
widened in the higher stress regions.
[0076] FIGS. 33B-33C depict stress distributions comparing a fixed
beam width design (FIG. 33B) with a varying beam width design (FIG.
33C).
[0077] FIGS. 34A and 34B depict perspective views of multi-beam
cantilever embodiments providing additional compliant
structures.
[0078] FIGS. 35A and 35B provide perspective views of an example
undeflected and deflected two-beam cantilever structure.
[0079] FIGS. 36A and 36B provide perspective views of an example
undeflected and deflected six-beam cantilever structure.
[0080] FIGS. 36C-36E provide perspective views of multi-beam
cantilever structures having shortened beam lengths or beams of
different thicknesses.
[0081] FIGS. 36F-36K provide various side views of multi-beam
cantilever structures having non perpendicular bridging
elements.
[0082] FIGS. 37A-37F provide perspective views of various C-shaped
cantilever probe embodiments.
[0083] FIGS. 38A-38B provide a perspective view of another C-shaped
cantilever probe embodiment and a stress distribution associated
with deflecting the probe, respectively.
[0084] FIGS. 39A-39C provide perspective views of example probe
arrays according to some embodiments of the invention.
[0085] FIGS. 39D-39J provide perspective views of various
cantilever probe structures according to some embodiments of the
invention.
[0086] FIGS. 40A-40C provide perspective views of a sample
cantilever probe array at different levels of magnification
[0087] FIGS. 41A-41R provide perspective views of various
cantilever probe structures according to some embodiments of the
invention.
[0088] FIG. 42A provides a side view of a sample cantilever probe
structure having two compliant support structures
[0089] FIG. 42B provides a side view of a sample tensional
cantilever probe structure.
[0090] FIGS. 43A-43C provide two side views (43A and 43C) and a
perspective view (43B) of various possible mechanical
configurations of pivot structures and cantilever beams.
[0091] FIGS. 44A-44C provide examples of cantilever structures have
added compliant elements
[0092] FIGS. 45A-45B provide perspective views, at two different
magnifications, of a sample probe array that may be formed
initially using thick layers and finally using thin layers to allow
desired placement of critical structures.
[0093] FIGS. 46A and 46B provide perspective views of a cantilever
probe design having a small cantilever located on a larger
cantilever such that the large cantilever provides most vertical
compression while the small cantilever provides significant
scrubbing displacement.
[0094] FIGS. 46C-46E provides three side views of two small
cantilevers located on a larger cantilever where it is believed
that the two small cantilevers can aid in achieving adequate
scrubbing during vertical compression of the probe.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION
[0095] FIGS. 1A-1G, 2A-2F, and 3A-3C illustrate various features of
one form of electrochemical fabrication. 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 various embodiments of
various aspects of the invention to yield enhanced embodiments.
Still other embodiments may be derived from combinations of the
various embodiments explicitly set forth herein.
[0096] FIGS. 4A-4G illustrate various stages in the formation of a
single layer of a multi-layer fabrication process where a second
metal is deposited on a first metal as well as in openings in the
first metal where its deposition forms part of the layer. In FIG.
4A, a side view of a substrate 82 is shown, onto which patternable
photoresist 84 is cast as shown in FIG. 4B. In FIG. 4C, a pattern
of resist is shown that results from the curing, exposing, and
developing of the resist. The patterning of the photoresist 84
results in openings or apertures 92(a)-92(c) extending from a
surface 86 of the photoresist through the thickness of the
photoresist to surface 88 of the substrate 82. In FIG. 4D, a metal
94 (e.g. nickel) is shown as having been electroplated into the
openings 92(a)-92(c). In FIG. 4E, the photoresist has been removed
(i.e. chemically stripped) from the substrate to expose regions of
the substrate 82 which are not covered with the first metal 94. In
FIG. 4F, a second metal 96 (e.g., silver) is shown as having been
blanket electroplated over the entire exposed portions of the
substrate 82 (which is conductive) and over the first metal 94
(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.
[0097] In FIG. 4H the result of repeating the process steps shown
in FIGS. 4B-4G several times to form a multi-layer structure are
shown where each layer consists of two materials. For most
applications, one of these materials is removed as shown in FIG. 41
to yield a desired 3-D structure 98 (e.g. component or device).
[0098] The various embodiments, alternatives, and techniques
disclosed herein may be combined with or be implemented via
electrochemical fabrication techniques. Such combinations or
implementations may be used to form multi-layer structures using a
single patterning technique on all layers or using different
patterning techniques on different layers. For example, different
types of patterning masks and masking techniques may be used or
even techniques that perform direct selective depositions may be
used without the need for masking. For example, conformable contact
masks may be used during the formation of some layers or during
some selective deposition or etching operations while
non-conformable contact masks may be used in association with the
formation of other layers or during other selective deposition or
etching operations. 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) may be used, and 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) may be used.
[0099] In many embodiments, cantilever probes offer good compliance
and may be formable from fewer layers than is required for forming
vertically extending probes (see for example U.S. Patent
Application Nos. 60/603,030, 10/772,943 and 60/641,341 each of
which is incorporated herein by reference) but at the cost of
consuming more substrate area. In some situations cantilevered
probes may be more preferred than vertically extending probes while
in other situations the reverse may be true.
[0100] A simplified example of two cantilever probe structures are
shown in FIG. 5A. As indicated in FIG. 5A, the probe structure
includes three main elements, a support column which is bonded to a
substrate (e.g. a space transformer), a cantilever arm element that
has a proximal end attached to the column and a distal end on which
a contact structure or tip exists. As can be seen, the column does
not possess any integral base element that extends significantly
under the cantilever arm element.
[0101] It is possible to make cantilever probe structures having
multiple support structures. FIG. 5B shows such a structure having
two support columns. The cantilever arm may be considered to have a
distal end at which a contact tip is located, a proximal end or
central portion at which one of the support columns makes contact
and an extension region (i.e. end opposite to the distal end) at
which a second column attaches to the arm. In such a multi-support
structure, the cantilever portion may be considered that portion
which extends from the distal end to the contact point with the
closest column.
[0102] In the context of the present application, cantilever probe
structures are those that have a projected length in the XY plane
that is greater than (or even substantially greater than) an
overall height of the structure where the height is assumed to
extend along a Z-axis which corresponds to the axis along which
primary movement of the tip is to occur during contact with a pad
or other circuit element. Alternatively, a cantilever structure may
be considered that for which the length of a cantilever portion as
projected onto an XY plane is substantially greater than the amount
of deflection that may be expected of the device along a Z-axis
when a tip element is made to contact a pad or other circuit
element.
[0103] Some embodiments of the invention provide probe structures,
or methods of fabricating probes, where the probe structures
include a modified base structure that is located adjacent to, or
in proximity to, a substrate (e.g. space transformer) and is bonded
to it. The modified base structure comprises an elongated structure
that has a footprint that (1) underlies at least a portion of a
cantilever arm of the probe, or (2) the elongated structure
comprises at least two elongated components where a vector sum of a
footprint of each of at least two of the elongated components
underlies at least a portion of the cantilever arm. Underlying the
cantilever arm means that the footprint or vector sum is located
between the substrate and the cantilever arm in a plane (or other
path) defined by the motion of the cantilever structure during
compression.
[0104] In some preferred embodiments, the footprint or vector sum
underlies the cantilever arm by at least 25% of the cantilever
length, more preferably by 50% of its length, even more preferably
by 75% of its length, and most preferably by 90% of its length or
more. In some preferred embodiments, the base directly contacts the
substrate while in other preferred embodiments only a portion of
the base directly contacts the substrate, while in still other
preferred embodiments, the base does not directly contact the
substrate but is spaced therefrom and adhered thereto by at least
one intermediate material (e.g. solder).
[0105] Examples of various enhanced base-structure embodiments of
the invention are depicted in FIG. 6 to FIG. 17. FIG. 6 depicts an
embodiment of a probe array which comprises two probe structures
102a and 102b each having a cantilever portion or arm 104. At a
distal end 105 of the cantilever portion a contact tip 106 is
located. The probes are adhered to a substrate 108 by a bonding
material 110 which is only located at that portion of the elongated
base structure 112 that is directly below riser 114. The distal end
and the intermediate portions of the elongated base structure are
not bonded to the substrate but are located at or slightly spaced
from the substrate. By the extended length of the base structure
112 (which is set to match the length of the cantilever arm) of the
elongated base structure, significant plastic, or at least
non-elastic, dislocations of the probe tip (that might otherwise
result from yield strength loss or yield strength short comings of
the bonding material) are minimized or eliminated.
[0106] FIG. 7 depicts an embodiment of a probe array which
comprises two probe structures 122a and 122b each having a
cantilever portion 124 and an elongated base structure or
structures whose footprint or vector sum extends the length of the
cantilever arm. The probe structure is bonded to the substrate at
the distal end of the elongated base structure such that no net
shear or tensional force exists on the bonding material 130 as a
result of compressional deflection of the probes toward the
substrate.
[0107] FIG. 8 depicts an embodiment which includes probe structures
142a and 142b which are similar to those shown in FIGS. 6 and 7
with the exception that the probes are bonded to the substrate at
both a proximal end 151 (relative to the riser 154) and at a distal
end 153 of an elongated base structure via bonding material
150.
[0108] FIG. 9 depicts an embodiment similar to that of FIG. 8 where
bonding occurs at both proximal and distal ends of the elongated
base structure but where the base structure has a footprint or
vector sum (if more than one base structure exists per probe) that
extends beyond a projection of the distal end of the cantilever arm
onto the substrate.
[0109] FIG. 10 depicts an embodiment similar to that of FIGS. 8 and
9 where bonding occurs at both proximal and distal ends of the
elongated base structure but where the base structure has a
footprint or vector sum (if more than one base structure exist per
probe) that does not extend as far as a projection of the distal
end of the cantilever arm onto the substrate.
[0110] FIG. 11 depicts an embodiment similar to that of FIG. 6 but
where bonding occurs only at the distal ends of the elongated base
structures but where the proximal end of the base structure is
supported by a standoff 215.
[0111] FIG. 12 depicts an embodiment similar to those of FIGS. 6-8
where the length or vector sum of the lengths of the elongated base
structure or structures, respectively, match the projection or
length of the cantilever arm of the probe. However, in the
embodiment of FIG. 12 both the distal end and proximal end of the
elongated base structures are supported by standoffs 233a and 231a,
respectively, and where bonding between the base structure and
substrate occurs in a mid-region of the base structure via bonding
material 230.
[0112] FIG. 13 depicts an embodiment where the elongated base
structure 252 is located adjacent to and in direct contact with the
substrate 248 and where bonding occurs between the distal end of
the elongated base structure and a portion of the substrate
adjacent to the distal end via a bonding material 250.
[0113] FIG. 14 depicts an embodiment where both distal and proximal
ends of an elongated base structure are bonded to the substrate. In
this embodiment the base structure is not a relatively thin
featureless structure but instead is a structure having variable
thickness (e.g. a thickness that decreases near the distal end of
the elongated base structure to strengthen the base while not
causing interference between the cantilever arm and base structure
during deflection of the cantilever). Of course in other
embodiments, other configurations are possible.
[0114] FIG. 15 depicts an embodiment where riser 294 takes on a
desired configuration (as opposed to being a beam-like structure
that extends perpendicular to a surface of the substrate). The
desired configuration may, for example, be a configuration that
allows enhanced deflection. Of course, in other embodiments other
configurations are possible.
[0115] In still other embodiments the cantilever arms may take on
various configurations (other than the beam like configurations
shown in the above examples).
[0116] FIG. 16A depicts a side view of a cantilever probe which
includes a tip element 302, a cantilever arm element 304, a riser
306, and an elongated base structure 308 while FIGS. 16B-16F depict
top views of various example alternative configurations of the
probe structure of FIG. 16A. In FIG. 16A, the width (i.e. the
dimension extending in and out of the page) of the elongated base
structure, or structures, of the probe can not be seen.
[0117] FIG. 16B depicts a simple case where the base structure in a
top view is completely shadowed by the cantilever 304 and riser
portion 302 of the probe.
[0118] FIG. 16C depicts a case where the width of the base
structure 308 along its entire length is wider than the width of
the cantilever structure 304 as evidenced by the fact it can be
seen on each side of the cantilever structure. It is believed that
such widening may help with stabilization of the probe and more
particularly in enhancing its ability to avoid unintended motions
outside the plane of the probe (i.e. outside the plane defined by
the primary length and height of the probe) particularly in
circumstances where the yield strength of the bonding material may
begin to fail.
[0119] FIG. 16D depicts a case where only a single portion of the
elongated base structure 308 near the distal end of the structure
has a width that exceeds that of the cantilever portion 304.
[0120] FIG. 16E is similar to 16D with the exception that two
distinct regions of the base structure 308 extend beyond the width
of the cantilever portion 304 of the probe.
[0121] FIG. 16F depicts two side-by-side probes where the base
structures 308 fan out to become wider at the distal end of the
base structure than at the proximal end. In some alternative
embodiments, the fanned out elongated base structure may be two
elongated structures laid out in a V-shaped configuration (similar
to that of FIG. 17 but not as pronounced). In the embodiment of
FIG. 16F, it is assumed that the base structures may be formed with
their desired configuration while still being spaced far enough
apart to allow formation to occur.
[0122] FIG. 17 depicts an array of three probe structures in
separated side views (on the left of the figure) and in a top view
(to the right of the figure). In the embodiment of FIG. 17 the base
structure of each probe comprises two elongated structures 408a and
408b that are configured in a V-shape. Portions of the base
structure for each probe overlap base structures from adjacent
probes in the plane of the substrate (e.g. in the XY plane) but do
not contact the base structures of the neighboring probes due to a
designed vertical offset between crossing structures. Elongated
base structure 408a is displaced above the substrate by a desired
distance and an extension element 409 joints the distal end of
structure 408a to the substrate or to a bonding material located
between the structure and the substrate. Elongated base structure
408a is formed above an elongated structure 408b of a neighboring
probe such that a desired gap exists between them. It is believed
that probe arrays such as those shown in FIG. 17 may offer more
stability in situations where the probes will be subject to forces
or displacements perpendicular to the plane defined by the
cantilever arm and space it sweeps out during compressional motion
toward the substrate.
[0123] FIG. 18A and 18B provide two perspective views of an example
cantilever probe which includes a base element with a footprint
that partially underlies the cantilever portion of the probe. The
cantilever portion of the probe is depicted as comprising a
relative complex configuration that starts off relative wide and
deep at the proximal end that then becomes thinner and shallower
near the distal end (i.e. the tip end).
[0124] FIG. 19 depicts a top view of an array 302 of seven
cantilever probes elements 304A-304G which form a linear contact
pattern along line 306. In the figure, cantilever portions are
shown with dashed lines and are shown as narrower in width than the
riser portion (e.g. support or column portion) and base portion. In
the figure, bonding regions 312A-312D are shown as being still
wider. The desired spacing between the adjacent probing locations
is obtained via left-right interlacing of the adjacent probing
locations (i.e. one location is probed from the right while the
adjacent probing locations are probed from the left, etc.). The
left-right interlacing alone does not allow small enough pitch by
itself and the remaining pitch reduction is obtained by locating
bonding pad locations at different positions on adjacent probes.
Positions of bonding pads have interlaced positions along the
x-axis so that they do not contact and overlap along the
y-axis.
[0125] FIGS. 20A and 20B show perspective views from the top and
bottom, respectively, of a six probe array where all probes extend
from the same side of a contact line and where bonding region
interlacing is used to allow the probes to be located closer
together than would be allowed without the interlacing.
Furthermore, the array shows that probe elements are provided with
openings along the base which allow bonding elements (e.g. bumps or
pads) to overlap the footprint of adjacent probes without causing
electrical shorting between the probes. In other embodiments, two
step shifting, for example, may be used instead of the three-step
shifting as illustrated in the example of FIGS. 20A and 20B.
[0126] FIG. 21 shows a perspective view of two sets of six element
probe arrays that form two contact lines and which have the same
interlacing and bonding location compensation openings as noted
with regard to FIGS. 20A and 20B.
[0127] FIG. 22A depicts perspective views of two probe elements 352
and 354, having an alternative pattern of widened bonding regions
and their use in forming an example four probe array 356. FIG. 22B
depicts a top view of an extended array of the probes 352 and 354
where the spacing between adjacent probes and the overlapping XY
regions containing adjacent probes may be better seen. FIG. 22B is
analogous in its depictions to those shown in FIG. 19. It is noted
that only half the probes in this array use the base structure that
have footprints that underlie their cantilever portions. In
alternative embodiments, it may be possible to form probes 354 with
enhanced base structures (i.e. base structure that offer footprints
that underlie their cantilever portions) by using the opening
technique of FIGS. 20A, 20B, and 21.
[0128] Various alternatives to the embodiments set forth above
exist and will be apparent to those of skill in the art in view of
the teachings set forth herein. For example, EFAB.TM. fabrication
techniques may be used to form all or a portion of the probe
structures. For example, arrays may be formed using more than the
two or three probes illustrated in FIGS. 6-17. In some embodiments,
probe tips may be formed separately from the main body of the probe
array and then transferred to the main body of the probes. In some
embodiments, adhesion between probes and substrates may be formed
by solder bonding, brazing, diffusion bonding, via other bonding
techniques, and/or via a combination of approaches. In some
embodiments each probe may have multiple contact tips, each probe
may have multiple cantilever arms, and/or each probe may have one
or more risers. In some embodiments different probes of an array
may take on different configurations. In some embodiments, the
probe structures with enhanced base configurations may be used even
when the probes are formed directly on the substrate while in other
embodiments their use may be limited to embodiments where probes
are formed on temporary substrates and then transferred to
permanent substrates. In some embodiments, transfer bonding may
occur one probe element at a time or in arrays that contain
multiple pre-aligned probes.
[0129] In some embodiments, probe elements may be formed in an
up-right configuration (i.e. building axis is parallel or
anti-parallel to that of the primary motion when the probe tip or
array of probe tips are deflected) or in a side-ways or rotated
configuration. In the up-right configuration more probes may be
formed simultaneously in a given substrate area while in the
side-ways configurations fewer layers are need to form any given
probe.
[0130] In some embodiments cantilever probes may have one or more
support elements (e.g. columns or risers) that extend from a base
element to the cantilever portion of the probe along a vertical
path, a path containing a vertical component, or even along a
convoluted path. In embodiments, where multiple support elements
are provided, not all support elements need to be bonded or
attached to the cantilever structure but instead they may merely
contact the cantilever structure either all of the time or only
during particular amounts of deflection of the structure.
[0131] In some embodiments, the simple cantilever structures
depicted may be replaced by more complex or sophisticated
structures. Cantilever elements may have more complex
configurations.
[0132] Some embodiments of the present invention provide cantilever
structures that have base elements which can be made to interlock
with structures on a substrate so as to limit or restrain movement
between the base and the substrate in a Z direction and to limit or
restrain movement of the base relative to the substrate along a
dimension which is perpendicular to the Z direction. These
interlocking base structures may or may no have portions which
extend beyond the riser portion of the cantilever probe.
[0133] FIGS. 23A-23C depict examples of cantilever structures
502A-502C which have base elements 504A-504C which have "L" shapes
and which may be made to slide into a slotted structure on a
substrate and particularly a slotted structure that has an undercut
into which the base of the "L" may slide into. Such a base
structure is depicted in FIG. 24A while FIG. 24B depicts probe
structure 502A which has been slid into slotted structure 512 of
FIG. 24A.
[0134] Slotted structure 512 of FIG. 24A includes a cantilever
element 514 which offers some compliance and a snug fit as a probe
element is slid into place. In some embodiments, the base structure
of a probe element may take on an "L" shape configuration while in
other embodiments the base structure may have an upside down "T"
configuration such that when slid into a base element the structure
is locked into place on each side of the cantilever element. A "T"
shaped configuration is more clearly seen on the base elements of
probe elements 602A, 602B and 602C of FIG. 26.
[0135] Once slid into place the probe elements may be held in
position and in electrical contact with the substrate by frictional
forces or alternatively they may be locked into place by an
appropriate mechanical mechanism. In still other embodiments the
probe elements may be bonded to the base structures by solder or
conductive epoxy or the like. In some embodiments the probe
elements may be removable (if damaged) so that a replacement
element may be inserted. Such replacement may occur by simply
reversing the motion that led to mating in the first place, or by
releasing locking elements or by heating to melt a bonding material
or controlled etching to remove a bonding material or the like.
[0136] FIGS. 25A depicts a perspective view of a mounting structure
that includes four clips 522A-522D as opposed to the two slots of
FIG. 24A. FIG. 25A shows where a slotted base structure like 512 of
FIG. 24A would be located using dashed outlines 524. In the
embodiment of FIG. 25A, two clips hold down each side of a "T"
shaped base structure. In some alternative embodiments, it may be
sufficient to have a single pair of clips hold a probe having an
"L" or "T" shaped base structure or having a base structure having
tabs that extend from an elongated base in those locations where
clips are to be located.
[0137] FIGS. 25B depicts a top view of two sets of clip elements
522A-522D for two adjacent cantilever probes that are to be located
with a pitch corresponding to distance P.sub.1. With the clips
aligned with one another for holding adjacent probes, the probes
can not be formed any closer together because of a minimum feature
size limitation. FIG. 25C depicts a top view of two sets of clip
elements 522A-522D for two adjacent cantilever probes where the
locations of the clips have been shifted so that they may be
located closer together thereby allowing probes held by the sets of
clips to be located at a distance P.sub.2 from one another which is
smaller than distance P.sub.1.
[0138] The probe elements of FIGS. 23A-23C or other probe elements
of some embodiments of the present invention may be formed in an
upright position (i.e. with the height extending in the vertical or
Z direction and with layers being formed parallel to the XY plane.
In other embodiments the structures may be formed lying sideways
such that fewer layers are necessary to form the structures. If
formed on their sides multiple probes may be formed above one
another and interlacing of probe elements may occur to greatly
improve fabrication efficiency and yield.
[0139] Clip or retention elements into which probe elements will
have their bases inserted may be formed directly on space
transformers or other desired substrates or may alternatively be
transferred to space transformers or other desired substrates using
transfer techniques disclosed in a number of the applications set
forth below.
[0140] FIG. 26 depicts probe elements 602A-602C lying in a sideways
orientation and stacked one above the other as they may be formed
according to some embodiments of the invention.
[0141] In some embodiments, it may be possible to form and transfer
probe elements in groups while in other embodiments, transfer of
probe structures to space transformers or other desired substrates
may occur manually or by pick-and-place machines.
[0142] FIG. 27 depicts an alternative embodiment of the invention
where each probe element 602 or selected probe elements 602 are
separated from other probe elements by shields 604A and 604B. These
shield elements may provide improved impedance characteristics for
the signals that will be carried by probes 602. Shield elements
604A and 604B may be formed by techniques similar to those used in
forming probe elements 602. In some embodiments as previously
noted, probe elements may be made to mechanically lock into
position on base structures.
[0143] FIGS. 28A-28C show an example of a probe element 702, having
a protrusion 710 on its base, which may be slid into retention
structure 704 on a substrate 700 and locked in place by locking
element 706 which may be rotated up and down. When locking element
706 is in the down position probe element 402 may be slid into
position causing arms 708A and 708B to split apart and then reseat
around protrusion 710. If the probe element 702 needs to be
replaced, locking mechanism 708 may be rotated to an upper position
which releases element 710 and allows probe 702 to be removed from
base 704. In another alternative embodiment the cantilever element
514 of base 512 of FIG. 24A may have a locking element located at
its distal end which may be used to engage a hole or notch in a
base element, thus locking the probe and base together once the
desired mating position is reached.
[0144] Release of the probe element may occur by a tab or other
mechanism which would allow cantilever portion 514 to rotate upward
(not shown). It should be understood that other locking elements
may be used in fixing probe elements in desired positions relative
to otherwise unrestrained directions of motion. Such elements may
exist on the base structure itself as discussed with regard to FIG.
24A may exist on the backside of base structure as discussed in
association with FIGS. 28A-28C, or alternatively, they may be
located on the entry side of the base structure. Such locking
elements on the entry side might be spring-loaded elements that may
be momentarily pushed aside to allow the probe element to be mated
with the base and thereafter may be allowed to move back into a
locking position.
[0145] In still other embodiments, contact between the base
structure and the probe element may occur by spring-like elements
that may be forced into compression or tension during the loading
of the probe element and which force may be used to constrain the
probe element from further motion once located in its desired
position.
[0146] In still other embodiments no locking elements may be
necessary but it may be desirable to include fixed stop elements
located on the probe and or base element that can interact with the
other components and which may be used to fix and/or detect proper
seating position once the probe is loaded into the base. In the
various embodiments of the invention discussed above, loading of
probe elements into base structures occurs by linear motion by the
mating of a slot or clips and a rail-like element.
[0147] In other embodiments, however, probe structures and base
structures may be designed to allow insertion and retention by
rotational motion with or without linear motion. Such rotational
motion may occur along an axis parallel to the Z direction or
alternatively it may occur along an axis of rotation perpendicular
to the Z direction (e.g. a 30.degree.-90.degree. rotation along the
X- or Y-axis).
[0148] In still other embodiments, the rail-like structure forming
or on the base of the probe may be replaced by tabs. In still other
embodiments, the rail-like structure on or forming the base of the
probe may be moved to the substrate while clips or retention
structures may be moved to the base of the probe.
[0149] As with other embodiments of cantilever probe structures,
the contact portion of the probe structure may be formed from a
different material than the rest of the structure or it may
alternatively be formed from the same material. The configuration
of the tip may occur via the same process that is used to form the
rest of the probe structure or alternatively may involve the use of
a different process which may occur before, after, or in parallel
to the formation of the rest of the structure and which may be
bonded to the rest of the structure during formation or may be
transferred after formation of both the tip element and the rest of
the probe structure. In use of the probe elements of some
embodiments, it will typically be desired to have arrays of probe
elements which may be located in close proximity to one another and
for which different properties may be desired. As such, it may be
preferential in some embodiments to mix and match probe designs
with one another to achieve various results such as desired spacing
between elements or desired probe tip location in a given plane or
desired probe tip locations in multiple planes.
[0150] In another group of embodiments of the present invention, a
single large or thick cantilever beam may be replaced by an array
of smaller beams (i.e. 2 or more beams). Such multi-beam structures
can achieve both a relatively large displacement and a large force.
For example, using such structures it may be possible to achieve a
100 .mu.m displacement at 6 grams of force at the probe tip with no
plastic deformation of the cantilever probe. To achieve this with a
single beam, the beam needs to be long enough to provide sufficient
displacement at a reasonable stress, and thick enough to achieve a
reasonably high force. As a result, typically the single cantilever
beam must be larger for a given application.
[0151] In the present group of embodiments, a composite beam is
formed from many thinner beams. A very thin beam, even if it is
only about 1 mm in length can deform in excess of 100 .mu.m without
plastic deformation. But a thin beam does not produce a large
force. By stacking multiple thin beams and supporting them such
that they all displace together, their force contributions add
individually, while each is able to reach the desired deflection
without plastic deformation. An example of a cantilever probe
formed from such a stacked set of beams are depicted in the side
view of FIG. 29A and the perspective view of FIG. 29B. The
cantilever 722 of FIGS. 29A and 29B includes a column or riser 724,
a plurality of beams 726A-726P each connected on a proximal end to
the column 724 and on the distal end to a joining structure 728
that includes a tip 730 or a may be arranged as shown in FIG. 29A
and 29B.
[0152] By varying the length, width, thickness, and number of
beams, virtually any desired load-deflection characteristic may be
achieved.
[0153] Often, it is desirable to keep the length and width at or
below some required specification limit, such as for example a 1 mm
beam length and 40 or 50 .mu.m width, so that the probes and arrays
of probes can accommodate the most demanding fine-pitch IC layouts.
By fixing the length and width, having only thickness and number of
beams to adjust may not provide sufficient design flexibility to
meet all desired specifications. Another useful design feature is
to effectively shorten the beam length by adding additional
supports along the beam length. An example of such shortening or
bridging elements is depicted in the perspective views of FIGS. 30A
and 30B where like elements to those found in FIGS. 29A and 29B are
labeled with like reference numbers and where the single bridging
element of FIG. 30A is labeled with reference number 732 and the
dual bridging elements of FIG. 30B are labeled with reference
numbers 734A and 734B. These bridging elements may be considered a
way to array multiple composite beams horizontally rather than
vertically. Since beam stiffness has a length cubed relationship,
shortening the beams in this manner can provide substantially
higher stiffness (and therefore force) even with very thin
beams.
[0154] A common design objective in microprobes is to achieve as
large a load and deflection as possible in as small a volume as
possible. This means that the spring probe must absorb as much
elastic deformation energy as possible. To achieve this and avoid
plastic deformation, it is desired to distribute stress throughout
the structure as evenly and efficiently as possible. The composite
beam designs may incorporate several features which help to
distribute stress. In a cantilever supported at one end, most of
the stress occurs at the fixed end. But the way the composite beams
are rigidly supported at both ends prevents rotation at the beam
ends. This creates stress at both beam ends, which may distribute
stress more efficiently (i.e. uniformly) than that resulting from a
single beam. Furthermore, compared with a single beam, where most
of the stress may be located primarily on the top and bottom of the
beam and where the middle of the beam bears little load, an array
of thinner beams more efficiently distributes stress throughout its
volume. Finally, adding the additional bridging elements as
exemplified in the embodiment of FIGS. 30A and 30B stress may be
spread more uniformly throughout the structure. FIGS. 31 and FIG.
32 provide stress distribution plots for given amounts of tip
deflection for the probe designs of FIGS. 30A and 30B.
[0155] Stress is distributed more efficiently in the embodiment of
FIG. 30B than in FIG. 30A as can be seen form the plots of FIGS. 32
and 31 due to the presence of the extra post.
[0156] Another possible way to improve stress distribution is to
create a varying beam width along the length of the cantilever, for
example making the beam narrower in lower stress regions and wider
in higher stress regions. An example of such an alternative design
configuration is shown in FIG. 33A. FIGS. 33B-33C depict stress
distributions comparing a no taper or varying beam width design
(FIG. 33B) with a taper or varying beam width design (FIG. 33C)
where it can be seen that the variable beam width design shows a
more uniform stress distribution.
[0157] One added benefit of constraining the beam rotation at both
ends is that it may reduce the scrub length compared with a single
beam cantilever.
[0158] In other embodiments, additional spring elements (i.e.
compliant elements) may be added. As shown in the perspective views
of FIGS. 34A and 34B a large spring 744A or 744B, respectively, may
be added on the common support post (e.g. riser or column) near the
base of the structure. Some additional rotation capability may be
introduced which reduces the amount of pure bending that the beams
must undergo.
[0159] In other embodiments, different numbers of beam elements may
be used to form the composite beam. In some embodiments, the
composite beam may include only two elements. An example of a two
beam probe is depicted in an un-deflected perspective view of FIG.
35A and a deflected perspective view of FIG. 35B. In other
embodiments 3, 4, 5, 6 or more beams may be present. An example of
a six beam probe is depicted in an un-deflected perspective view of
FIG. 36A and a deflected perspective view of FIG. 36B.
[0160] In some embodiments each beam of the composite need not be
of the same length and in fact some beams may end short of a
contact end of the beam as exemplified in the embodiment of FIG.
36C. In other embodiments, each beam of the composite may not have
a common thickness with all other beams as exemplified in the probe
design of FIG. 36D. In still other embodiments, beam thicknesses
may be common for some or all of the beams. In some embodiments
each beam of the composite may extend to the contact end of the
beam but each beam or some beams may have different lengths with
shorter beams merging into a larger beam at one or both ends of the
cantilever as exemplified in the probe design of FIG. 36E.
[0161] In still other embodiments it is possible to aid in
spreading stress more uniformly using other structural designs. For
example bridging elements may be made to connect beams in an
oblique manner instead of a vertical manner. Examples of such
oblique designs are illustrated in FIGS. 36F-36K. FIGS. 36F and 36G
depict entire cantilever probe structures 752 and 762 sitting on
substrates 754 and 764 respectively while FIGS. 36H-361
schematically depict side views of only the cantilever portions of
alternative probe configurations. As shown in FIG. 36F, bridging
elements 756-1, 756-2, to 756-3 may run in a common non-vertical
direction (e.g. as indicated by elements 756-2, to 756-3) or in
opposing directions (e.g. as indicated by elements 756-1, to
756-2). As shown in FIG. 36G, bridging elements may run in a
non-vertical direction that matches a bridging pattern existing at
either one or both of the column end or tip end of multibeam
structure. FIG. 36H indicates that bridging elements 766-1 may all
run in the same direction and further that they need not have a
linear aspect to them but instead ma be curved. FIG. 361 indicates
that the bridging elements 766-2 may have more complex or compound
curved shapes (e.g. S-shapes). FIG. 36J indicates that the bridging
elements 766-3, 766-4, and 766-5 may each have different and even
opposing configurations. FIG. 36K indicates that the bridging
elements 766-6 to 766-9 may take on progressively varying slopes or
configurations as the beams are traversed from support column to
final bridging element at the tip.
[0162] In some embodiments, it may be possible to determine optimal
bridging element location or locations and configuration or
configurations by performing a design simulation (e.g. initially
without bridging elements) and locating regions of minimum stress
and maximum stress and then designing and locating the bridging
elements according to the determined stress patterns and repeating
the simulation and design process one or more times as necessary.
For example, it may be desirable to locate bridging elements in the
regions of minimum stress and to cause them to take on
configurations that match or at least partially match the minimum
stress configurations. It is generally desirable to minimize
discontinuities and as such, it is preferred that layer thicknesses
as small as possible be used (to achieve minimum discontinuities
based on layer pixilation) when the probes are formed in an upright
position (i.e. the axis of deflection of the probe matches the axis
of stacking layers). When building probes lying on their sides it
is preferred to minimum discontinuities by making smooth
transitions from cantilever beams to bridging elements.
[0163] In some embodiments, multi-beam cantilever need not end at a
common riser or support column but they may instead extend directly
to the substrate or even follow a more circuitous route such as the
"C" shapes of FIGS. 37A-37F.
[0164] The probe structure 772 of the example of FIG. 36A provides
an example of a compound cantilever-like structure with only a
forward C-structure support 774 which can be attached to a
substrate, a contact or tip region 776 on an upper bridging element
778, and three parallel C-shaped cantilever compliant elements
780-1, 780-2, and 780-3 that attach the upper bridging element 776
and the support structure 774.
[0165] The probe structure 772' of FIG. 37B provides an example of
a probe structure similar to that of FIG. 37A with the exception
that a rear cantilever support 782 and an upper and extra
cantilever element 780-4 connects the rear cantilever support 782
to the upper bridging element 778'.
[0166] FIG. 37C provides an example of a probe structure 772''
similar to that of FIGS. 37B with the exception that a base element
784 connects the rear cantilever support 782 to the C-structure
support 774. Furthermore some sample dimensions (in microns)
provide a rough scale for the probe structure.
[0167] FIG. 37D provides an example of a probe structure 772'''
similar to that of FIGS. 37B with the exception C-shaped cantilever
elements 780-2' and 780-3' are merged into a common vertical
support 790 and share a common horizontal bottom element 792.
Furthermore, some sample dimensions (in microns) provide a rough
scale for the probe structure.
[0168] FIG. 37E provides an example of a probe structure 772''''
similar to that of FIGS. 37B with the exception C-shaped cantilever
elements 780-3 of FIG. 37B is removed so that the probe include a
primary cantilever 780-4 and second C-shaped cantilevers 780-1 and
780-2. Furthermore, some sample dimensions (in microns) provide a
rough scale for the probe structure.
[0169] FIG. 37F provides an example of a probe structure 772''''
similar to that of FIGS. 37C with the exception that the upper
cantilever portions of C-shaped cantilever elements 780-1'' and
780-2'' have progressively decreasing thicknesses as they approach
the upper bridging element 778''. Furthermore, some sample
dimensions (in microns) provide a rough scale for the probe
structure.
[0170] FIGS. 38A and 38B provide a perspective view and a deflected
side view of another embodiment of the invention. The probe of
FIGS. 38A and 38B has some similarities to that of FIG. 37F. The
probe structure 802 of the examples of FIGS. 38A and 38B provides a
compound cantilever like structure with a rear cantilever support
804, a forward C-structure support 806, a base 808, a contact
region 810, a primary cantilever arm 812, upper S-bending arms 814a
and 814b, lower S-bending arms 816a and 816b, and forward upper
bridging region 818a, forward lower bridging element 818b (which as
illustrated is an extension of support 806. Arms 814a, 814b, 816a
and 816b will tend to bend in an s-shape when tip 810 is put under
load and is relatively urged toward base 806. In this embodiment a
plurality of arms (814a and 814b) contact bridge 818c to form the
upper element of a C-shape while a plurality of arms (816a and
816b) contact bridge 818c to form the lower element of a C-shape.
This inner end joining of upper and lower arms causes the
individual arms of the C-clamp to flex in more of an S-shape than a
normal cantilever shape. This tends to stiffen the overall spring
response and tends to reduce scrub. In this example, the upper most
arm (cantilever arm 812) does not connect to bridging element 818c
(i.e. does not form part of the C-Clamp) but instead remains free
to convey force to the support end 804 of the base while the
elements of the C-clamp tend to direct force to support 806. In
other alternative embodiments cantilever arm 812 may be connected
directly to a bridging element like 818c. In some alternatives of
the present embodiment the inner most gap (formed by arms 814b,
bridge 818c, and arm 816b may have an opening with a stepped "V"
shape (as shown) which may help distribute stress while also
creating more clearance for the top section to compress toward the
bottom section of the C-shaped portion of the structure. In other
alternative embodiments the inner most portions of the C-clamp may
provide other configurations.
[0171] FIG. 38B depicts a simulated 40 um deflection of the tip of
the structure under a 4 gram load. The structure is 1.5 mm long and
30 um wide. An array of such structures may be formed or placed
adjacent to one another (e.g. on a 50 um pitch) to yield a desired
contact pattern. The structure may be formed on or bonded to a
substrate. For example, adhesion between the structure and the
substrate may occur along the length of the base of the structure
or alternatively it may occur at one or both of the rear or front
support columns.
[0172] In other embodiments various other modification are
possible. For example heights of post portions of the composite
beam may be varied and/or heights of contact regions may be varied.
As an additional example, tip structures (not shown) may be added
or formed on the ends of the contact regions. As another example
lengths of cantilever arms may be changed. As a further example,
multiple rear supported cantilever beams may act in parallel with
multiple C-shaped cantilever-like structures (e.g. connected to the
same tip bridging element). As an even further example, various
features of the previously presented embodiments may be combined
with one another to form new cantilever probe designs having
various properties of the interest and/or enhanced fabrication
methods may be achieved for a given probe design.
[0173] FIG. 39A provides a perspective view of an array of
cantilever probe structures that may be formed according to some
embodiments of the invention. The width of these sample probe
structures decrease along the cantilever length
[0174] FIG. 39B provides a perspective view of another array of
cantilever probe elements (support columns or risers are not shown)
which have different contact heights, different approach positions
and heights, and different structural sizes and cross-sectional
configurations (e.g. which may be useful in providing different
current carrying capabilities, different spacing possibilities,
different compliances, ability to make electric contact with
different types and heights of pads simultaneously), and different
probe tip configurations (e.g. which might allow probe tips to be
configured to a specific contact situations and materials). Use of
probes of varying size, positioning, height and the like may reduce
the complexities of power and ground signal duplication.
[0175] FIG. 39C provides a perspective view of another array of
cantilever probe elements (support column or risers are not shown).
In the example of FIG. 39C, the probe elements that reach past
other probe elements are not shown as interleaved but instead as
coming in above and below one another. In other probe arrays, any
appropriate individual probe elements of desired configurations may
be used and be made to contact pads, bumps or other surfaces to be
tested.
[0176] In various embodiments of the present invention probes may
be formed on their permanent substrate while in other embodiments
probes may be formed on a sacrificial substrate and then
transferred, via one or more steps, to a permanent substrate where
transfer may occur individual probe by individual probe, as an
entire array, or as separate groups of incomplete arrays. Spacing
between transferred probes or array portions may be different than
spacing between the probes or array portions as they are formed. In
some embodiments, probes may be transferred in groups associated
with individual die. When using a sacrificial building material, as
used in some embodiments of the present invention, it is possible
to form probes on a temporary substrate and transfer them to a
permanent substrate (through one or more transfer operations) and
have the probes have different contact heights since the
sacrificial material may support the different probe positions
during formation, and potentially during transfer, after which the
sacrificial material may be removed to release the probes.
[0177] FIGS. 39D-39J depict various additional examples of
cantilever probe designs that may be formed using electrochemical
fabrication techniques. These different probe types may be formed
simultaneously and have similar heights or they may start or end at
different levels.
[0178] FIG. 40A-40C provide perspective views of another array of
probe elements that might actually be considered multiple arrays of
elements forming a super array. The probes are cantilever type
probes and they are arranged in groups. Groups of probe arrays such
as depicted may, for example, have application in the area of
memory chip testing.
[0179] FIGS. 41A-41R depict a variety of different cantilever probe
structures according to various embodiments of the invention. These
cantilever probe structures may be formed using electrochemical
fabrication techniques or they may be formable using other
fabrication methods.
[0180] Tapered probes such as those shown in FIGS. 41M, 41N, 41O,
and 41P may be used to disperse stress more uniformly through out a
structure and thereby lower maximum stress level and thereby
increase probe reliability and life.
[0181] FIG. 42A depicts an example of an alternative cantilever
probe embodiment. In the embodiment of FIG. 42A, the cantilever
probe 822 includes a beam section 824 having a contact tip region
826 and at least two compliant support structures 828-1 and 828-2,
where the support structure 828-1 that is distal from the tip
region is less compliant than the support structure 828-2 which is
located closer to the tip. In other alternatives more than two
compliant support structures may be used. In still other
embodiments, any of a variety of compliant structures may be used
as support structures.
[0182] FIG. 42B depicts another alternative cantilever probe
structure. Cantilever probe structures of this type may be
considered to be a "tensional cantilevers" as opposed to a
"compressional cantilevers" since the compliant element of the
cantilever is place under tension instead of under compression. As
illustrated the cantilever 832 includes a beam structure 834 which
is connected to a compliant structure 836 on or near one end and
has a tip 838 on or near the opposite end. The structure also
includes a substantially non-compliant pivot structure 840. During
operation the tip 838 is pressed downward toward substrate causing
compliant element 836 to bend and after the beam 834 contacts the
pivot structure 840, continued downward movement of the tip causes
the compliant structure 836 to be place in tension. In some
alternative embodiments, the pivot structure may have a curved or
pointed upper surface, and/or the beam 834 may remain in contact
with the pivot structure even when no load is placed on the tip. In
some alternative embodiments the pivot bar and cantilever bar may
be pinned together as shown in FIG. 43A where the pivot structure
840' may hold a pin 842 that extends cantilever 840' (the compliant
structure and probe tip are not shown). In some variations of this
embodiment, the pin, the pivot structure and the cantilever arm may
be formed simultaneously in their desired positions. In some
embodiments side supports 844R and 844L may retain the pivot
structure 840'' and cantilever bar 834 in desired positions as
shown in FIG. 43B. In still other alternative embodiments the side
supports 844' may be attached to the cantilever bar 834 as opposed
to the pivot structure 840''' as shown in FIG. 43C.
[0183] In other variations of the tensional cantilever, the
effective spring constant of the compliant structure may be
increased or decreased by changing the ratio (CP/TP) of distances
from the compliant structure to the pivot structure (CP) and from
the tip to the pivot structure (TP). If the ratio is greater than
one (i.e. the compliant structure is further form the pivot
structure than the probe tip) the effective spring constant is
increased. If on the other hand the ratio is less than one, the
effective spring constant is decreased. Similarly, if the ratio is
greater than one, the useable over-travel is decreased, whereas if
the ratio is less than one, the useable over-travel of the probe is
greater than the over travel capability of the compliant element
alone.
[0184] Pivoting cantilever structures may also be used in
compression when the compliant element and the probe tip are on the
same side of the pivot structure. Such probe structures may be used
to enhance the effective compliance and effective over travel
capabilities of a compliant structure (i.e. the actual compliance
and over travel of the probe as a whole). If the CP/TP ratio is
greater than one the effective compliance decreases and the over
travel capabilities also decrease. On the other hand, if the ratio
is less than one, the compliance and the over travel capabilities
of the probe are enhanced.
[0185] In still other alternative embodiments, additional compliant
structures may be added in parallel to a cantilever probe which
will increase the stiffness of the probe. Examples of such
structures are provided in FIGS. 44A-44C. FIG. 44A adds a single
compliant structure 854 to a cantilever structure 852. FIG. 44B
adds two compliant structures 854 to a cantilever structure 852'.
In both FIG. 44A and 44B the compliant structures were added
between an extended base 856 and the cantilever arm 858 itself. In
FIG. 44C a compliant structure is added below the cantilever
structure 858 and mount directly to a substrate 860. In other
alternative embodiments, the cantilever structures may take on any
of a variety of forms (e.g. the various forms set forth in other
embodiments herein). In still other alternative embodiments, the
added compliant structures may take on any of a variety of forms
(e.g. the various forms set forth in the other embodiments herein
or in embodiments set forth in one or more of the over patent
applications incorporate herein by reference). The extra spring
constant added by the addition of one or more added compliant
elements may be useful in some embodiments where it is not possible
to make all cantilevers have the same effective length but where it
is still desired that each have a similar effective compliance.
[0186] In forming cantilever probes using electrochemical
fabrication techniques there may be a minimum width for the probes
or a minimum spacing between probes (i.e. minimum feature size)
that may make it difficult to achieve desired pitch placements.
Such minimums are sometimes layer thickness dependent (e.g. the
smaller the layer thickness the smaller the minimum feature size).
Many cantilevers for use in probing DRAMs are preferably hundreds
of microns tall, which encourages us to use layer thicknesses as
large as possible (e.g. 50 um tall layers). But this also result in
large minimum feature sizes (e.g. 50 um widths). This in turn puts
a limit on the pitch of our probe structures based on a need of
each probe to be separated by a gap (e.g. 100 micron
center-line-to-center-line spacing). In some embodiments it may be
possible to achieve improved pitch (i.e. decreased pitch) by
forming a portion of cantilever probe structures using thinner
layers which can have smaller minimum features sizes. Improved
pitch may be achieved for example by staggering the cantilevers
(with every other probe coming from the opposite direction and by
using the thinner layers (e.g. 12 um thick layers) for the last few
layers of the tip or before the tip.
[0187] An example of this embodiment is shown in FIGS. 45A-45B
which provide perspective views (full view FIG. 45A and close up of
tips FIG. 45B) of a cantilever array having probe tips located on a
common line where the body of the cantilever is made of 50 micron
thick layers, stacked one on the other in the z-direction, and a 50
micron minimum feature size and where the top few layers are made
from 20 micron layers and thus can be made to come into closer
proximity to each other and thus can be located side by side so
that tips may be made co-linear. Embodiments of this type allow
probe arrays or other structures to be formed with appropriate
(i.e. fine or high resolution) features sizes in critical areas
while simultaneously minimizing the number of layers that are used
in forming the structures
[0188] Multi beam probes as discussed herein above provide a very
high overtravel for their lengths but tend to offer minimal scrub
length (length of horizontal movement which causes scratching
through any oxide or other contaminates that may hinder the ability
to achieve good electrical contact between a probe and a target
surface). In some embodiments, enhanced tip structures may be used
to improve scrub length. In some such embodiments, a small
cantilever may be placed at the end of a larger cantilever. The
compliance of the small cantilever is preferably set, or its over
travel is limited, so that it does not exceed a stress level which
could damage it but bends enough to provide additional scrub. One
such embodiment is illustrated in FIGS. 46A and 46B. A small
cantilever 882, having probe tip 884 is mounted at the distal end
of a larger cantilever 872. The large cantilever provides most of
the vertical compliance while the smaller cantilever contributes
significantly to scrubbing. In one example, scrubbing increased
from 7 to 12 um by the addition of the small cantilever while not
sacrificing maximum stress level.
[0189] In another embodiment, a multi-tip small cantilever may be
used on a larger cantilever as illustrated in FIGS. 46C-46E. Large
cantilever 472' has located on its distal end a non-contact tip
structure 474 on which two smaller cantilevers 482-1 and 482-2 are
mounted. FIG. 46D illustrates the scrubbing action that can occur
under compression. FIG. 46E indicates that the relative lengths of
the small cantilevers are A and B respectively. The ratio of A and
B may dictate or at least contribute to the relative amount of
scrubbing performed by each tip.
[0190] In some embodiments of the invention special tip structures
may be bonded to fabricated cantilevers or alternative cantilevers
may be formed upside down and the cantilever structure may be
formed on the tip as build up begins. In still other embodiments,
tip coating material may be deposited onto the tip portion of the
cantilever or onto the whole cantilever after it is formed. In
still other embodiments, material deposited and patterned during
formation of the cantilever may be used as tip material. For
example the layer, or layers, of the cantilever may be considered
the tip and these layers may simply be made from tip material.
[0191] Some embodiments may employ diffusion bonding or the like to
enhance adhesion between successive layers of material. Various
teachings concerning the use of diffusion bonding in
electrochemical fabrication processes are set forth in U.S. patent
application Ser. No. 10/841,384 which was filed May 7, 2004 by
Cohen et al. which is entitled "Method of Electrochemically
Fabricating Multilayer Structures Having Improved Interlayer
Adhesion" and which is hereby incorporated herein by reference as
if set forth in full.
[0192] Further teachings about microprobes and electrochemical
fabrication techniques are set forth in a number of U.S. Patent
Applications: (1) U.S. Patent Application No. 60/533,975 by Kim et
al., which was filed on Dec. 31, 2003, and which is entitled
"Microprobe Tips and Methods for Making"; (2) U.S. Patent
Application No. 60/533,947 by Kumar et al., which was filed on Dec.
31, 2003, and which is entitled "Probe Arrays and Method for
Making"; (3) U.S. Patent Application No. 60/574,737 by Cohen et
al., which was filed May 26, 2004, and which is entitled
"Electrochemical Fabrication Method for Fabricating Space
Transformers or Co-Fabricating Probes and Space Transformers",; (4)
U.S. Patent Application No. 60/533,897 by Cohen et al. which was
filed on Dec. 31, 2003, and which is entitled "Electrochemical
Fabrication Process for Forming Multilayer Multimaterial Microprobe
structures"; (5) U.S. Patent Application No. 60/540,511 by Kruglick
et al, which was filed on Jan. 29, 2004, and which is entitled
"Electrochemically Fabricated Microprobes", (6) U.S. Patent
Application No. 10/772,943, by Arat et al., which was filed Feb. 4,
2004, and which is entitled "Electrochemically Fabricated
Microprobes"; (7) U.S. Patent Application No. 60/582,690, filed
Jun. 23, 2004, by Kruglick, and which is entitled "Cantilever
Microprobes with Base Structures Configured for Mechanical
Interlocking to a Substrate"; and (8) U.S. Patent Application No.
60/582,689, filed Jun. 23, 2004 by Kruglick, and which is entitled
"Cantilever Microprobes with Improved Base Structures and Methods
for Making the Same". These patent filings are each hereby
incorporated herein by reference as if set forth in full herein.
The techniques disclosed explicitly herein may also benefit by
combining them with the techniques disclosed in U.S. patent
application Ser. No. 11/029,180 filed concurrently herewith by Chen
et al. and entitled "Pin-Type Probes for Contacting Electronic
Circuits and Methods for Making Such Probes"; U.S. Patent
Application No. 60/641,341 filed concurrently herewith by Chen et
al. and entitled "Vertical Microprobes for Contacting Electronic
Components and Method for Making Such Probes"; U.S. patent
application Ser. No. 11/029,217 filed concurrently herewith by Kim
et al. and entitled "Microprobe Tips and Methods For Making"; U.S.
patent application Ser. No. 11/028,958 filed concurrently herewith
by Kumar et al. and entitled "Probe Arrays and Methods for Making";
and U.S. patent application Ser. No. 11/029,221 filed concurrently
herewith by Cohen et al. and entitled "Electrochemical Fabrication
Process for Forming Multilayer Multimaterial Microprobe
Structures".
[0193] Further teachings about planarizing layers and setting
layers thicknesses and the like are set forth in the following U.S.
Patent Applications which were filed Dec. 31, 2003: (1) U.S. Patent
Application No. 60/534,159 by Cohen et al. and which is entitled
"Electrochemical Fabrication Methods for Producing Multilayer
Structures Including the use of Diamond Machining in the
Planarization of Deposits of Material" and (2) U.S. Patent
Application No. 60/534,183 by Cohen et al. and which is entitled
"Method and Apparatus for Maintaining Parallelism of Layers and/or
Achieving Desired Thicknesses of Layers During the Electrochemical
Fabrication of Structures". These patent filings are each hereby
incorporated herein by reference as if set forth in full herein.
The techniques disclosed explicitly herein may also benefit by
combining them with the techniques disclosed in U.S. patent
application Ser. No. 11/029,220 filed concurrently herewith by
Frodis et al. and entitled "Method and Apparatus for Maintaining
Parallelism of Layers and/or Achieving Desired Thicknesses of
Layers During the Electrochemical Fabrication of Structures".
[0194] Additional teachings concerning the formation of structures
on dielectric substrates and/or the formation of structures that
incorporate dielectric materials into the formation process and
possibility into the final structures as formed are set forth in a
number of patent applications: (1) U.S. Patent Application No.
60/534,184, by Cohen, which as filed on Dec. 31, 2003, and which is
entitled "Electrochemical Fabrication Methods Incorporating
Dielectric Materials and/or Using Dielectric Substrates"; (2) U.S.
Patent Application No. 60/533,932, by Cohen, which was filed on
Dec. 31, 2003, and which is entitled "Electrochemical Fabrication
Methods Using Dielectric Substrates"; (3) U.S. Patent Application
No. 60/534,157, by Lockard et al., which was filed on Dec. 31,
2004, and which is entitled "Electrochemical Fabrication Methods
Incorporating Dielectric Materials"; (4) U.S. Patent Application
No. 60/574,733, by Lockard et al., which was filed on May 26, 2004,
and which is entitled "Methods for Electrochemically Fabricating
Structures Using Adhered Masks, Incorporating Dielectric Sheets,
and/or Seed Layers that are Partially Removed Via Planarization";
and U.S. Patent Application No. 60/533,895, by Lembrikov et al.,
which was filed on Dec. 31, 2003, and which is entitled
"Electrochemical Fabrication Method for Producing Multi-layer
Three-Dimensional Structures on a Porous Dielectric". These patent
filings are each hereby incorporated herein by reference as if set
forth in full herein. The techniques disclosed explicitly herein
may also benefit by combining them with the techniques disclosed in
U.S. patent application Ser. No. 11/029,216 filed concurrently
herewith by Cohen et al. and entitled "Electrochemical Fabrication
Methods Incorporating Dielectric Materials and/or Using Dielectric
Substrates" and U.S. Patent Application No. 60/641,292 filed
concurrently herewith by Dennis R. Smalley and entitled "Method of
Forming Electrically Isolated Structures Using Thin Dielectric
Coatings".
[0195] 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.
TABLE-US-00001 U.S. Pat App No, Filing Date U.S. App Pub No, Pub
Date Inventor, Title 09/493,496 - Jan. 28, 2000 Cohen, "Method For
Electrochemical Fabrication" 10/677,556 - Oct. 1, 2003 Cohen,
"Monolithic Structures Including Alignment and/or Retention
Fixtures for Accepting Components" 10/830,262 - Apr. 21, 2004
Cohen, "Methods of Reducing Interlayer Discontinuities in
Electrochemically Fabricated Three- Dimensional Structures"
10/271,574 - Oct. 15, 2002 Cohen, "Methods of and Apparatus for
Making High 2003-0127336A - Jul. 10, 2003 Aspect Ratio
Microelectromechanical Structures" 10/697,597 - Dec. 20, 2002
Lockard, "EFAB Methods and Apparatus Including Spray Metal or
Powder Coating Processes" 10/677,498 - Oct. 1, 2003 Cohen,
"Multi-cell Masks and Methods and Apparatus for Using Such Masks To
Form Three-Dimensional Structures" 10/724,513 - Nov. 26, 2003
Cohen, "Non-Conformable Masks and Methods and Apparatus for Forming
Three-Dimensional Structures" 10/607,931 - Jun. 27, 2003 Brown,
"Miniature RF and Microwave Components and Methods for Fabricating
Such Components" 10/841,100 - May 7, 2004 Cohen, "Electrochemical
Fabrication Methods Including Use of Surface Treatments to Reduce
Overplating and/or Planarization During Formation of Multi-layer
Three-Dimensional Structures" 10/387,958 - Mar. 13, 2003 Cohen,
"Electrochemical Fabrication Method and 2003-022168A - Dec. 4, 2003
Application for Producing Three-Dimensional Structures Having
Improved Surface Finish" 10/434,494 - May 7, 2003 Zhang, "Methods
and Apparatus for Monitoring 2004-0000489A - Jan. 1, 2004
Deposition Quality During Conformable Contact Mask Plating
Operations" 10/434,289 - May 7, 2003 Zhang, "Conformable Contact
Masking Methods and 20040065555A - Apr. 8, 2004 Apparatus Utilizing
In Situ Cathodic Activation of a Substrate" 10/434,294 - May 7,
2003 Zhang, "Electrochemical Fabrication Methods With 2004-0065550A
- Apr. 8, 2004 Enhanced Post Deposition Processing" 10/434,295 -
May 7, 2003 Cohen, "Method of and Apparatus for Forming Three-
2004-0004001A - Jan. 8, 2004 Dimensional Structures Integral With
Semiconductor Based Circuitry" 10/434,315 - May 7, 2003 Bang,
"Methods of and Apparatus for Molding 2003-0234179 A - Dec. 25,
2003 Structures Using Sacrificial Metal Patterns" 10/434,103 - May
7, 2004 Cohen, "Electrochemically Fabricated Hermetically
2004-0020782A - Feb. 5, 2004 Sealed Microstructures and Methods of
and Apparatus for Producing Such Structures" 10/841,006 - May 7,
2004 Thompson, "Electrochemically Fabricated Structures Having
Dielectric or Active Bases and Methods of and Apparatus for
Producing Such Structures" 10/434,519 - May 7, 2003 Smalley,
"Methods of and Apparatus for 2004-0007470A - Jan. 15, 2004
Electrochemically Fabricating Structures Via Interlaced Layers or
Via Selective Etching and Filling of Voids" 10/724,515 - Nov. 26,
2003 Cohen, "Method for Electrochemically Forming Structures
Including Non-Parallel Mating of Contact Masks and Substrates"
10/841,347 - May 7, 2004 Cohen, "Multi-step Release Method for
Electrochemically Fabricated Structures" 10/841,300 - May 7, 2004
Cohen, "Methods for Electrochemically Fabricating Structures Using
Adhered Masks, Incorporating Dielectric Sheets, and/or Seed layers
That Are Partially Removed Via Planarization"
[0196] Various other embodiments of the present invention exist.
Some embodiments may not use any blanket deposition process and/or
they may not use a planarization process. Some embodiments may use
selective deposition processes or blanket deposition processes on
some layers that are not electrodeposition processes. Some
embodiments, for example, may use nickel, nickel-phosphorous,
nickel-cobalt, gold, copper, tin, silver, zinc, solder, rhodium,
rhenium as structural materials while other embodiments may use
different materials. Some embodiments, for example, may use copper,
tin, zinc, solder or other materials as sacrificial materials. Some
embodiments may use different structural materials on different
layers or on different portions of single layers. Some embodiments
may use photoresist, polyimide, glass, ceramics, other polymers,
and the like as dielectric structural materials.
[0197] It will be understood by those of skill in the art that
additional operations may be used in variations of the above
presented fabrication embodiments. These additional operations may,
for example, perform cleaning functions (e.g. between the primary
operations discussed above), they may perform activation functions
and monitoring functions.
[0198] It will also be understood that the probe elements of some
aspects of the invention may be formed with processes which are
very different from the processes set forth herein and it is not
intended that structural aspects of the invention need to be formed
by only those processes taught herein or by processes made obvious
by those taught herein.
[0199] Many other alternative embodiments will be apparent to those
of skill in the art upon reviewing the teachings herein. Further
embodiments may be formed from a combination of the various
teachings explicitly set forth in the body of this application.
Even further embodiments may be formed by combining the teachings
set forth explicitly herein with teachings set forth in the various
applications and patents referenced herein, each of which is
incorporated herein by reference.
[0200] In view of the teachings herein, many further embodiments,
alternatives in design and uses of the instant invention 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.
* * * * *