U.S. patent application number 12/899071 was filed with the patent office on 2011-04-07 for miniature rf and microwave components and methods for fabricating such components.
This patent application is currently assigned to Microfabrica Inc.. Invention is credited to Christopher A. Bang, Elliott R. Brown, Adam L. Cohen, John D. Evans, Morton Grosser, Michael S. Lockard, Dennis R. Smalley.
Application Number | 20110080236 12/899071 |
Document ID | / |
Family ID | 27575405 |
Filed Date | 2011-04-07 |
United States Patent
Application |
20110080236 |
Kind Code |
A1 |
Brown; Elliott R. ; et
al. |
April 7, 2011 |
Miniature RF and Microwave Components and Methods for Fabricating
Such Components
Abstract
RF and microwave radiation directing or controlling components
are provided that may be monolithic, that may be formed from a
plurality of electrodeposition operations and/or from a plurality
of deposited layers of material, that may include switches,
inductors, antennae, transmission lines, filters, and/or other
active or passive components. Components may include
non-radiation-entry and non-radiation-exit channels that are useful
in separating sacrificial materials from structural materials.
Preferred formation processes use electrochemical fabrication
techniques (e.g. including selective depositions, bulk depositions,
etching operations and planarization operations) and
post-deposition processes (e.g. selective etching operations and/or
back filling operations).
Inventors: |
Brown; Elliott R.;
(Glendale, CA) ; Evans; John D.; (Arlington,
VA) ; Bang; Christopher A.; (San Diego, CA) ;
Cohen; Adam L.; (Los Angeles, CA) ; Lockard; Michael
S.; (Lake Elizabeth, CA) ; Smalley; Dennis R.;
(Newhall, CA) ; Grosser; Morton; (Menlo Park,
CA) |
Assignee: |
Microfabrica Inc.
|
Family ID: |
27575405 |
Appl. No.: |
12/899071 |
Filed: |
October 6, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11842947 |
Aug 21, 2007 |
7830228 |
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12899071 |
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10309521 |
Dec 3, 2002 |
7259640 |
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11842947 |
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60338638 |
Dec 3, 2001 |
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60340372 |
Dec 6, 2001 |
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60379133 |
May 7, 2002 |
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60379182 |
May 7, 2002 |
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60379184 |
May 7, 2002 |
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60415374 |
Oct 1, 2002 |
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60379130 |
May 7, 2002 |
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60392531 |
Jun 27, 2002 |
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Current U.S.
Class: |
333/208 ;
205/122 |
Current CPC
Class: |
H01P 11/00 20130101;
H01P 11/005 20130101; H01P 11/007 20130101; B81B 2201/042 20130101;
B33Y 10/00 20141201; B33Y 70/00 20141201; H01P 3/06 20130101; G01P
15/0802 20130101; C25D 1/003 20130101; H05K 3/4647 20130101; H01P
1/202 20130101; Y10T 29/49002 20150115; G01P 15/125 20130101; Y10T
29/49016 20150115; Y10T 29/49018 20150115; H01P 5/183 20130101 |
Class at
Publication: |
333/208 ;
205/122 |
International
Class: |
H01P 1/207 20060101
H01P001/207; C25D 5/02 20060101 C25D005/02 |
Claims
1. A coaxial RF or microwave component that preferentially passes a
radiation in a desired frequency band, comprising: a. at least one
RF or microwave radiation entry port in a conductive structure; b.
at least one RF or microwave radiation exit port in the conductive
structure; c. at least one passage, substantially bounded on the
sides by the conductive structure, through which RF or microwave
radiation passes when traveling from the at least one entry port to
the at least one exit port; d. a central conductor extending along
the at least one passage from the entry port to the exit port; and
e. at least one conductive spoke extending between the central
conductor and the conductive structure at each of a plurality of
locations where successive locations along the length of the
passage are spaced by approximately one-half of a propagation
wavelength, or an integral multiple thereof, within the passage for
a frequency to be passed by the component, wherein one or more of
the following conditions are met (1) the central conductor, the
conductive structure, and the conductive spokes are monolithic, (2)
a cross-sectional dimension of the passage perpendicular to a
propagation direction of the radiation along the passage is less
than about 1 mm, more preferably less than about 0.5 mm, and most
preferably less than about 0.25 mm, (3) more than about 50% of the
passage is filled with a gaseous medium, more preferably more than
about 70% of the passage is filled with a gaseous medium, and most
preferably more than about 90% of the passage is filled with a
gaseous medium, (4) at least a portion of the conductive portions
of the component are formed by an electrodeposition process, (5) at
least a portion of the conductive portions of the component are
formed from a plurality of successively deposited layers, (6) at
least a portion of the passage has a generally rectangular shape,
(7) at least a portion of the central conductor has a generally
rectangular shape, (8) the passage extends along a two-dimensional
non-linear path, (9) the passage extends along a three-dimensional
path, (10) the passage comprises at least one curved region and a
side wall of the passage in the curved region has a nominally
smaller radius than an opposite side of the passage in the curved
region and is provided with a plurality of surface oscillations
having smaller radii, (11) the conductive structure is provided
with channels at one or more locations where the electrical field
at a surface of the conductive structure, if it were there, would
have been less than about 20% of its maximum value within the
passage, more preferably less than 10% of its maximum value within
the passage, even more preferably less than 5% of its maximum value
within the passage, and most preferably where the electrical field
would have been approximately zero, (12) the conductive structure
is provided with patches of a different conductive material at one
or more locations where the electrical field at the surface of the
conductive structure, if it were there, would have been less than
about 20% of its maximum value within the passage more preferably
less than about 10% of its maximum value within the passage, even
more preferably less than about 5% of its maximum value within the
passage, and most preferably where the electrical field would have
been approximately zero, (13) mitered corners are used at least
some junctions for segments of the passage that meet at angles
between 60.degree. and 120.degree., and/or (14) the conductive
spokes are spaced at an integral multiple of one-half the
wavelength and bulges on the central conductor or bulges extending
from the conductive structure extend into the passage at one or
more locations spaced from the conductive spokes by an integral
multiple of approximately one-half the wavelength.
2. The component of claim 1 wherein condition one (1) is met and at
least one other condition is met.
3. The component of claim 1 wherein condition two (2) is met and at
least one other condition is met.
4. The component of claim 1 wherein condition three (3) is met and
at least one other condition is met.
5. The component of claim 1 wherein condition four (4) is met and
at least one other condition is met.
6. The component of claim 1 wherein condition five (5) is met and
at least one other condition is met.
7. The component of claim 1 wherein condition six (6) is met and at
least one other condition is met.
8. The component of claim 1 wherein condition seven (7) is met and
at least one other condition is met.
9. The component of claim 1 wherein condition eight (8) is met and
at least one other condition is met.
10. The component of claim 1 wherein condition nine (9) is met and
at least one other condition is met.
11. The component of claim 1 wherein condition ten (10) is met and
at least one other condition is met.
12. The component of claim 1 wherein condition eleven (11) is met
and at least one other condition is met.
13. The component of claim 1 wherein condition twelve (12) is met
and at least one other condition is met.
14. The component of claim 1 wherein condition thirteen (13) is met
and at least one other condition is met.
15. The component of claim 1 wherein condition fourteen (14) is met
and at least one other condition is met.
16. The component of claim 1 wherein the passage is substantially
filled with a solid dielectric material.
17. The component of claim 1 wherein the desired frequency band is
centered on a frequency greater than about 2 GHz, more preferably
greater than about 10 GHz, and even more preferably greater about
20 GHz.
18. The component of claim 1 wherein the at least one spoke
comprises one of (1) at least three sets of two spokes, more
preferably at least four sets of two spokes, and most preferably at
least five sets of two spokes, or (2) at least three sets of four
spokes, more preferably at least four sets of four spokes, and most
preferably at least five sets of four spokes.
19. An RF or microwave component that guides or controls radiation,
comprising: a. at least one RF or microwave radiation entry port
and at least one exit port within a conductive metal structure; and
b. at least one passage substantially bounded on the sides by the
conductive metal structure through which RF or microwave energy
passes when traveling from the at least one entry port; and c. at
least one branching channel along the at least one passage, wherein
the conductive metal structure surrounding the passage and the
channel in proximity to a branching region of the channel from the
passage is monolithic.
20. A method of manufacturing an RF device, comprising: a.
depositing a plurality of adhered layers of material, wherein the
deposition of each layer of material comprises, i. selective
deposition of at least a first material; ii. deposition of at least
a second material; and iii. planarization of at least a portion of
the deposited material; b. removing at least a portion of the first
or second material after deposition of a plurality of layers;
wherein a structural pattern resulting from the deposition and the
removal provides at least one structure that is usable as an RF
device.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 11/842,947 (Microfabrica Docket No.
P-US044-B-MF), filed on Aug. 21, 2007. The '947 application is a
continuation of U.S. patent application Ser. No. 10/309,521
(P-US044-A-MF), filed Dec. 3, 2002, now U.S. Pat. No. 7,259,640.
The '521 application claims benefit of U.S. Provisional Patent
Application Nos.: 60/338,638, filed on Dec. 3, 2001; 60/340,372,
filed on Dec. 6, 2001; 60/379,133, filed on May 7, 2002;
60/379,182, filed on May 7, 2002; 60/379,184, filed on May 7, 2002;
60/415,374, filed on Oct. 1, 2002; 60/379,130, filed on May 7,
2002; and 60/392,531 filed on Jun. 27, 2002. Each of these
applications is incorporated herein by reference as if set forth in
full herein.
FIELD OF THE INVENTION
[0002] Embodiments of this invention relate to the field of
electrical devices and their manufacture while specific embodiments
relate to RF and microwave devices and their manufacture. More
particularly embodiments of this invention relate to miniature
passive RF and microwave devices (e.g. filters, transmission lines,
delay lines, and the like) which may be manufactured using, at
least in part, a multi-layer electrodeposition technique known as
Electrochemical Fabrication.
BACKGROUND OF THE INVENTION
[0003] A technique for forming three-dimensional structures/devices
from a plurality of adhered layers was invented by Adam Cohen and
is known as Electrochemical Fabrication. It is being commercially
pursued by Microfabrica.RTM. Inc. (formerly MEMGen Corporation) of
Van Nuys, Calif. under the trade name EFAB.RTM.. This technique was
described in U.S. Pat. No. 6,027,630, issued on Feb. 22, 2000. This
electrochemical deposition technique allows the selective
deposition of a material using a unique masking technique that
involves the formation 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 conformable
portion 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, and the like. More specifically, in
the terminology of Microfabrica.RTM. Inc. (formerly MEMGen
Corporation) of Van Nuys, Calif. such masks have come to be known
as INSTANT MASKS.TM. and the process known as INSTANT MASKING.TM.
or INSTANT MASK.TM. plating. Selective depositions using
conformable contact mask plating may be used to form single layers
of material or may be used to form multi-layer structures. The
teachings of the '630 patent are hereby incorporated herein by
reference as if set forth in full herein. 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. 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, p 161, August 1998.
[0005] 2. 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, p 244, January 1999. [0006] 3. 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 MicroNanotechnology 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. 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. 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 being formed: [0015] 1. Selectively depositing at
least one material by electrodeposition upon desired region(s) of a
substrate. [0016] 2. Then, blanket depositing at least one
additional material by electrodeposition so that the additional
deposit covers both the region(s) that were previously selectively
deposited onto and the region(s) of the substrate that did not
receive any previously applied selective deposition(s). [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 additional 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
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 in
those locations 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.
CC mask plating selectively deposits material 22 onto a substrate
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 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] 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.
[0025] 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 cathode 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) 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.
[0026] 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 to 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.
[0027] 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 for driving the CC
masking process.
[0028] 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 the 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 for
driving the blanket deposition process.
[0029] The planarization subsystem 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.
[0030] In addition to teaching the use of CC masks for
electrodeposition purposes, the '630 patent also teaches that the
CC masks may be placed against a substrate with the polarity of the
voltage reversed and material may thereby be selectively removed
from the substrate. It indicates that such removal processes can be
used to selectively etch, engrave, and polish a substrate, e.g., a
plaque.
[0031] Electrochemical Fabrication provides the ability to form
prototypes and commercial quantities of miniature objects (e.g.
mesoscale and microscale 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 a new design and product spectrum
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 within the field or fields
of a specific application.
[0032] A need exists in the field of electrical components and
systems and particularly within the field of RF and microwave
components and systems for devices having reduced size, reduced
manufacturing cost, enhanced reliability, application to different
frequency ranges, and/or other enhanced features, and the like.
SUMMARY OF THE INVENTION
[0033] An object of various aspects of the invention is to provide
RF components having reduced size.
[0034] An object of various aspects of the invention is to provide
RF components producible with decreased manufacturing cost.
[0035] An object of various aspects of the invention is to provide
RF components with enhanced reliability.
[0036] An object of various aspects of the invention is to provide
RF components with design features making them applicable for use
within more frequency bands.
[0037] An object of various aspects of the invention is to provide
RF components with features that provide enhanced capability, such
as greater bandwidth.
[0038] Other objects and advantages of various aspects of the
invention will be apparent to those of skill in the art upon review
of the teachings herein. The various aspects of the invention, set
forth explicitly herein or otherwise ascertained from the teachings
herein, may address any one of the above objects alone or in
combination, or alternatively may address some other object of the
invention ascertained from the teachings herein. It is not intended
that all of these objects be addressed by any single aspect of the
invention even though that may be the case with regard to some
aspects.
[0039] It is an aspect of the invention to provide a microminiature
RF or microwave coaxial component, that includes an inner conductor
that has an axis which is substantially coaxial with an axis an
outer conductor wherein the inner and outer conductors are spaced
from one another by a dielectric gap wherein a minimum
cross-sectional dimension from an inside wall of the outer
conductor to an opposing inside wall of the outer conductor is less
than about 200 .mu.m. In a specific variation of this aspect of the
invention the outer conductor has a substantially rectangular
cross-sectional configuration.
[0040] It is an aspect of the invention to provide a coaxial RF or
microwave component that preferentially passes a radiation in a
desired frequency band, including: at least one RF or microwave
radiation entry port in a conductive structure; at least one RF or
microwave radiation exit port in the conductive structure; at least
one passage, substantially bounded on the sides by the conductive
structure, through which RF or microwave radiation passes when
traveling from the at least one entry port to the at least one exit
port; a central conductor extending along the at least one passage
from the entry port to the exit port; and at least one conductive
spoke extending between the central conductor and the conductive
structure at each of a plurality of locations where successive
locations along the length of the passage are spaced by
approximately one-half of a propagation wavelength, or an integral
multiple thereof, within the passage for a frequency to be passed
by the component, wherein one or more of the following conditions
are met (1) the central conductor, the conductive structure, and
the conductive spokes are monolithic, (2) a cross-sectional
dimension of the passage perpendicular to a propagation direction
of the radiation along the passage is less than about 1 mm, more
preferably less than about 0.5 mm, and most preferably less than
about 0.25 mm, (3) more than about 50% of the passage is filled
with a gaseous medium, more preferably more than about 70% of the
passage is filled with a gaseous medium, and most preferably more
than about 90% of the passage is filled with a gaseous medium, (4)
at least a portion of the conductive portions of the component are
formed by an electrodeposition process, (5) at least a portion of
the conductive portions of the component are formed from a
plurality of successively deposited layers, (6) at least a portion
of the passage has a generally rectangular shape, (7) at least a
portion of the central conductor has a generally rectangular shape,
(8) the passage extends along a two-dimensional non-linear path,
(9) the passage extends along a three-dimensional path, (10) the
passage includes at least one curved region and a side wall of the
passage in the curved region has a nominally smaller radius than an
opposite side of the passage in the curved region and is provided
with a plurality of surface oscillations having smaller radii, (11)
the conductive structure is provided with channels at one or more
locations where the electrical field at a surface of the conductive
structure, if it were there, would have been less than about 20% of
its maximum value within the passage, more preferably less than 10%
of its maximum value within the passage, even more preferably less
than 5% of its maximum value within the passage, and most
preferably where the electrical field would have been approximately
zero, (12) the conductive structure is provided with patches of a
different conductive material at one or more locations where the
electrical field at the surface of the conductive structure, if it
were there, would have been less than about 20% of its maximum
value within the passage more preferably less than about 10% of its
maximum value within the passage, even more preferably less than
about 5% of its maximum value within the passage, and most
preferably where the electrical field would have been approximately
zero, (13) mitered corners are used at least some junctions for
segments of the passage that meet at angles between 60.degree. and
120.degree., and/or (14) the conductive spokes are spaced at an
integral multiple of one-half the wavelength and bulges on the
central conductor or bulges extending from the conductive structure
extend into the passage at one or more locations spaced from the
conductive spokes by an integral multiple of approximately one-half
the wavelength.
[0041] It is an aspect of the invention to provide a coaxial RF or
microwave component that preferentially passes a radiation in a
desired frequency band, including: at least one RF or microwave
radiation entry port in a conductive structure; at least one RF or
microwave radiation exit port in the conductive structure; at least
one passage, substantially bounded on the sides by the conductive
structure, through which RF or microwave radiation passes when
traveling from the at least one entry port to the at least one exit
port; a central conductor extending along the at least one passage
from the entry port to the exit port; and at a plurality of
locations along a length of the passage, a pair of conductive stubs
extending from approximately the same position along a length of
the passage, one having an inductive property and the other having
a capacitive property, each extending into a closed channel that
extends from a side of the passage, wherein the successive
locations along the length of the passage are spaced by
approximately one-quarter of a propagation wavelength, or an
integral multiple thereof, within the passage for a frequency to be
passed by the component, wherein one or more of the following
conditions are met (1) the central conductor, the conductive
structure, and the conductive stubs are monolithic, (2) a
cross-sectional dimension of the passage perpendicular to a
propagation direction of the radiation along the passage is less
than about 1 mm, more preferably less than about 0.5 mm, and most
preferably less than about 0.25 mm, (3) more than about 50% of the
passage is filled with a gaseous medium, more preferably more than
about 70% of the passage is filled with a gaseous medium, and most
preferably more than about 90% of the passage is filled with a
gaseous medium, (4) at least a portion of the conductive portions
of the component are formed by an electrodeposition process, (5) at
least a portion of the conductive portions of the component are
formed from a plurality of successively deposited layers, (6) at
least a portion of the passage has a generally rectangular shape,
(7) at least a portion of the central conductor has a generally
rectangular shape, (8) the passage extends along a two-dimensional
non-linear path, (9) the passage extends along a three-dimensional
path, (10) the passage includes at least one curved region and a
side wall of the passage in the curved region has a nominally
smaller radius than an opposite side of the passage in the curved
region and is provided with a plurality of surface oscillations
having smaller radii, (11) the conductive structure is provided
with channels at one or more locations where the electrical field
at a surface of the conductive structure, if it were there, would
have been less than about 20% of its maximum value within the
passage, more preferably less than 10% of its maximum value within
the passage, even more preferably less than 5% of its maximum value
within the passage, and most preferably where the electrical field
would have been approximately zero, (12) the conductive structure
is provided with patches of a different conductive material at one
or more locations where the electrical field at the surface of the
conductive structure, if it were there, would have been less than
about 20% of its maximum value within the passage more preferably
less than about 10% of its maximum value within the passage, even
more preferably less than about 5% of its maximum value within the
passage, and most preferably where the electrical field would have
been approximately zero, (13) mitered corners are used at least
some junctions for segments of the passage that meet at angles
between 60.degree. and 120.degree., and/or (14) the conductive
stubs are spaced at an integral multiple of one-quarter the
wavelength and bulges on the central conductor or bulges extending
from the conductive structure extend into the passage at one or
more locations spaced from the conductive stubs by an integral
multiple of approximately one-half the wavelength.
[0042] It is an aspect of the invention to provide a coaxial RF or
microwave component that guides or controls radiation, including:
at least one RF or microwave radiation entry port in a conductive
structure; at least one RF or microwave radiation exit port in the
conductive structure; at least one passage substantially bounded on
the sides by the conductive structure through which RF or microwave
radiation passes when traveling from the at least one entry port to
the at least one exit port; a central conductor extending along a
length of the at least one passage from the entry port to the exit
port; and a branch in the passage down which a branch of the
central conductor runs and in which the central conductor shorts
against the conductive structure, wherein at least one of the
following conditions is met (1) the branch of the central
conductor, the conductive structure surrounding the branch, and a
location of shorting between the central conductor and the
conductive structure are monolithic, (2) at least a portion of the
central conductor or the conductive structure includes material
formed from a plurality of successively deposited layers, and/or
(3) at least a portion of the central conductor or the conductive
structure includes material formed by a plurality of
electrodeposition operations.
[0043] It is an aspect of the invention to provide an RF or
microwave component that guides or controls radiation, including:
at least one RF or microwave radiation entry port in a conductive
metal structure; at least one RF or microwave radiation exit port
in the conductive metal structure; at least one passage
substantially bounded on the sides by the conductive metal
structure through which RF or microwave energy passes when
traveling from the at least one entry port to the at least one exit
port; and wherein at least one the following conditions are met:
(1) at least a portion of the conductive metal structure includes a
metal formed by a plurality of electrodeposition operations, and/or
(2) at least a portion of the conductive metal structure includes a
metal formed from a plurality of successively deposited layers.
[0044] It is an aspect of the invention to provide an RF or
microwave component that guides or controls radiation, including:
at least one RF or microwave energy entry port in a conductive
metal structure; and at least one passage substantially bounded on
the sides by the conductive metal structure through which RF or
microwave energy passes when traveling from the at least one entry
port; and wherein at least a portion of the metal structure
includes a metal formed by a plurality of electrodeposition
operations and/or from a plurality of successively deposited
layers.
[0045] It is an aspect of the invention to provide an RF or
microwave component that guides or controls radiation, that
includes at least one RF or microwave radiation entry port and at
least one exit port within a conductive metal structure; and at
least one passage substantially bounded on the sides by the
conductive metal structure through which RF or microwave energy
passes when traveling from the at least one entry port; and at
least one branching channel along the at least one passage, wherein
the conductive metal structure surrounding the passage and the
channel in proximity to a branching region of the channel from the
passage is monolithic.
[0046] In a specific variation of each aspect of the invention the
production includes one or more of the following operations: (1)
selectively electrodepositing a first conductive material and
electrodepositing a second conductive material, wherein one of the
first or second conductive materials is a sacrificial material and
the other is a structural material; (2) electrodepositing a first
conductive material, selectively etching the first structural
material to create at least one void, and electrodepositing a
second conductive material to fill the at least one void; (3)
electrodepositing at least one conductive material, depositing at
least one flowable dielectric material, and depositing a seed layer
of conductive material in preparation for formation of a next layer
of electrodeposited material, and/or (4) selectively
electrodepositing a first conductive material, then
electrodepositing a second conductive material, then selectively
etching one of the first or second conductive materials, and then
electrodepositing a third conductive material, wherein at least one
of the first, second, or third conductive materials is a
sacrificial material and at least one of the remaining two
conductive materials is a structural material.
[0047] In a another specific variation of each aspect of the
invention the production includes one or more of the following
operations: (1) separating at least one sacrificial material from
at least one structural material; (2) separating a first
sacrificial material from (a) a second sacrificial material and (b)
at least one structural material to create a void, then filling at
least a portion of the void with a dielectric material, and
thereafter separating the second sacrificial material from the
structural material and from the dielectric material; and/or (3)
filling a void in a structural material with a magnetic or
conductive material embedded in a flowable dielectric material and
thereafter solidifying the dielectric material.
[0048] In another specific variation of each aspect of the
invention the component includes one or more of a microminiature
coaxial component, a transmission line, a low pass filter, a high
pass filter, a band pass filter, a reflection-based filter, an
absorption-based filter, a leaky wall filter, a delay line, an
impedance matching structure for connecting other functional
components, a directional coupler, a power combiner (e.g.,
Wilkinson), a power splitter, a hybrid combiner, a magic TEE, a
frequency multiplexer, or a frequency demultiplexer, a pyramidal
(i.e., smooth wall) feedhorn antenna, and/or a scalar (corrugated
wall) feedhorn antenna.
[0049] It is an aspect of the invention to provide an electrical
device, including: a plurality of layers of successively deposited
material, wherein the pattern resulting from the depositions
provide at least one structure that is usable as an electrical
device.
[0050] It is an aspect of the invention to provide a method of
manufacturing an RF device, including: depositing a plurality of
adhered layers of material, wherein the deposition of each layer of
material comprises, selective deposition of at least a first
material; deposition of at least a second material; and
planarization of at least a portion of the deposited material;
removal of at least a portion of the first or second material after
deposition of the plurality of layers; wherein a structural pattern
resulting from the deposition and the removal provides at least one
structure that is usable as an electrical device
[0051] It is an aspect of the invention to provide a method of
manufacturing a microdevice, including: depositing a plurality of
adhered layers of material, wherein the deposition of each layer of
material comprises, deposition of at least a first material;
deposition of at least a second material; and removing of at least
a portion of the first or second material after deposition of the
plurality of layers; wherein a structure resulting from the
deposition and the removal provides at least one structure that can
function as (1) a toroidal inductor, (2) a switch, (3) a helical
inductor, or (4) an antenna.
[0052] It is an aspect of the invention to provide an apparatus for
manufacturing a microdevice, including: means for depositing a
plurality of adhered layers of material, wherein the deposition of
each layer of material comprises utilization of, a means for
selective deposition of at least a first material; a means for
deposition of at least a second material; and means for removing at
least a portion of the first or second material after deposition of
the plurality of layers; wherein a structure resulting from use of
the means for depositing and the means for removing provides at
least one structure that can function as (1) a toroidal inductor,
(2) a switch, (3) a helical inductor, or (4) an antenna.
[0053] It is an aspect of the invention to provide a microtoroidal
inductor, including: a plurality of conductive loop elements
configured to form at least a portion of a toroidal pattern wherein
the toroidal pattern may be construed to have an inner diameter and
an outer diameter and wherein at least a portion of the plurality
of loops have a larger cross-sectional dimension in proximity to
the outer diameter than in proximity to the inner diameter.
[0054] It is an aspect of the invention to provide a microantenna,
including: an antenna that is at least in part separated from a
substrate.
[0055] It is an aspect of the invention to provide a method of
manufacturing an RF device, including: depositing a plurality of
adhered layers of material, wherein the deposition of each layer of
material comprises, selective deposition of at least a first
material; deposition of at least a second material; and
planarization of at least a portion of the deposited material;
removing at least a portion of the first or second material after
deposition of a plurality of layers; wherein a structural pattern
resulting from the deposition and the removal provides at least one
structure that is usable as an RF device.
[0056] Further aspects of the invention will be understood by those
of skill in the art upon reviewing the teachings herein. Other
aspects of the invention may involve combinations of the above
noted aspects of the invention. Other aspects of the invention may
involve methods and/or apparatus that can be used in implementing
one or more of the above aspects of the invention. These other
aspects of the invention may provide various combinations of the
aspects presented above as well as provide other configurations,
structures, functional relationships, and processes that have not
been specifically set forth above.
BRIEF DESCRIPTION OF THE DRAWINGS
[0057] FIGS. 1A-10 schematically depict side views of various
stages of a CC mask plating process.
[0058] 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.
[0059] FIGS. 3A-3C schematically depict side views of various
example subassemblies that may be used in manually implementing the
electrochemical fabrication method depicted in FIGS. 2A-2F.
[0060] FIG. 4A depicts a perspective view of a coaxial filter
element that includes shorting spokes.
[0061] FIG. 4B depicts a plan view of the coaxial filter of FIG. 4A
along lines 4B-4B
[0062] FIG. 4C depicts a plan view of the coaxial filter of FIG. 4A
along lines 4C-4C.
[0063] FIG. 5 depicts a plan view of the central portion of a
coaxial filter element showing five sets of filtering spokes (two
per set) along the length of the filter.
[0064] FIGS. 6A-6C depict end views, respectively, of rectangular,
circular, and elliptical filter elements each using sets of spokes
(four spokes per set).
[0065] FIG. 7A-7D depict examples of alternative spoke
configurations that may be used in filtering components.
[0066] FIGS. 8A and 8B illustrate perspective views of curved
coaxial filter components.
[0067] FIGS. 9A-9C depict alternative coaxial filter components
that use protrusions along the inner or outer conductor to aid in
filtering of signals.
[0068] FIG. 9D depicts a plan view of the central portion, along
the length, of an S-shaped two pole coaxial filter.
[0069] FIGS. 10A-10D depict plan views of the central portion,
along the length of horseshoe-shaped coaxial transmission lines
with varying degrees of mitering.
[0070] FIGS. 11A and 11B depict, respectively, plan views along the
central portions of a coaxial transmission line and a coaxial
filter component where wave-like oscillations are included on the
inside surface of the smaller radius side of the coaxial line.
[0071] FIG. 12A depicts a plan view (from the top) of the central
portion, along the length, of a linear three-pole band pass coaxial
filter using pairs of stubs to form each pole.
[0072] FIG. 12B depicts an end view of the filter of FIG. 12A
illustrating the rectangular configuration of the structure.
[0073] FIG. 12C depicts a plan view (from the top) of the central
portion, along the length of a curved three-pole band pass coaxial
filter with stub supports.
[0074] FIG. 13 depicts a plan view (from the top) of the central
portion, along the length of an S-shaped two-pole band pass coaxial
filter with stub supports.
[0075] FIGS. 14A and 14B depict perspective views of coaxial filter
elements embedded in sacrificial material and released from the
sacrificial material, respectively, where the outer conductor of
the coaxial components includes holes (in other than the intended
microwave entrance and exit openings).
[0076] FIGS. 15A-15D illustrate plots of transmission versus
frequency according to mathematical models for various filter
designs.
[0077] FIG. 16 depicts a flowchart of a sample electrochemical
fabrication process that uses a single conductive material and a
single dielectric material in the manufacture of a desired
device/structure.
[0078] FIG. 17A depicts an end view of a coaxial structure that can
be produced using the process of FIG. 16.
[0079] FIG. 17B depicts a perspective view of the coaxial structure
of FIG. 17A
[0080] FIGS. 18(a)-18(j) illustrate application of the process flow
of FIG. 16 to form the structure of FIGS. 17A and 17B.
[0081] FIG. 19 depicts a flowchart of a sample electrochemical
fabrication process that includes the use of three conductive
materials.
[0082] FIGS. 20A and 20B depict perspective views of structures
that include conductive elements and dielectric support structures
that may be formed according to extensions of the process of FIG.
19.
[0083] FIGS. 21A-21T illustrate application of the process flow of
FIG. 19 to form a coaxial structure similar to that depicted in
FIG. 20A where two of the conductive materials are sacrificial
materials that are removed after formation of the layers of the
structure and wherein a dielectric material is used to replace one
of the removed sacrificial materials.
[0084] FIGS. 22A-22C illustrate the extension of the removal and
replacement process of FIGS. 21R-21T.
[0085] FIGS. 23A and 23B depict a flowchart of a sample
electrochemical fabrication process that involves the use of two
conductive materials and a dielectric material.
[0086] FIG. 24 illustrates a perspective view of a structure that
may be formed using an extension of the process of FIGS. 23A and
23B.
[0087] FIGS. 25A-25Z illustrate side views of a sample layer
formation process according to FIGS. 23A and 23B to form a coaxial
structure with a dielectric material that supports only the inner
conductor.
[0088] FIGS. 26A-26E illustrate an alternative to the process of
FIGS. 25H-25K when a seed layer is needed prior to depositing the
first conductive material for the fourth layer of the
structure.
[0089] FIG. 27 depicts a perspective view of a coaxial transmission
line.
[0090] FIG. 28 depicts a perspective view of an RF contact
switch.
[0091] FIG. 29 depicts a perspective view of a log-periodic
antenna.
[0092] FIGS. 30A and 30B depict perspective views of a sample
toroidal inductor rotated by about 180 degrees with respect to one
another. FIG. 30C depicts a perspective view of toroidal inductor
formed according to an electrochemical fabrication process
[0093] FIGS. 31A and 31B depict perspective views of a spiral
inductor design and a stacked spiral inductor formed according to
an electrochemical fabrication process.
[0094] FIG. 31C depicts a variation of the inductors of FIGS. 31A
and 31B.
[0095] FIGS. 32A and 32B contrast two possible designs where the
design of FIG. 32B may offer less ohmic resistance than that of
FIG. 32A along with a possible change in total inductance.
[0096] FIGS. 33A and 33B depict a schematic representation of two
alternative inductor configurations that minimize ohmic losses
while maintaining a high level of coupling between the coils of the
inductor.
[0097] FIG. 34 depicts a perspective view of a capacitor.
[0098] FIGS. 35A and 35B depict a perspective view and a side view,
respectively, of an example of a variable capacitor 1102.
[0099] FIGS. 36A-36B depict end views of two example coaxial
structures where the central conductors are provided with a
cross-sectional configuration that increases their surface area
relative to their cross-sectional area.
[0100] FIG. 37 depicts a side view of an integrated circuit with
connection pads that are used for connecting internal signals (e.g.
clock signals) to low dispersions transmission lines for
communication with other portions of the integrated circuit.
[0101] FIGS. 38A and 38B illustrate first and second generation
computer controlled electrochemical fabrication systems (i.e.
EFAB.RTM. Microfabrication systems) that may be used in
implementing the processes set forth herein.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0102] A basic process of electrochemically forming layers of
multilayer three-dimensional structures was presented in FIGS.
1A-1C, while FIGS. 2A-2F applied the layer forming technique to a
plurality of overlaid layers (i.e. face-to-face contacting of
layers regardless of whether successive layers are formed above,
below, or beside previously formed layers). Various possible
apparatus components were discussed with the aid of FIGS. 3A-3C.
This apparatus and these processes may be used in forming
structures according to some embodiments of the invention. Other
apparatus and processes may also be used.
[0103] For example, in some embodiments, process variations may be
used to yield cavities within the conductive structures that are
filled completely or partially with a dielectric material, a
conductive material embedded in a dielectric, or a magnetic
material (e.g. a powdered ferrite material embedded in a dielectric
binder or sintered after placement). The dielectric material(s) may
be used as support structures to hold conducting elements separate
from one another and/or they may be used to modify the microwave
transmission or absorption properties of particular devices. A
dielectric may be incorporated into the structures during a
layer-by-layer buildup of the structures or may be back-filled in
bulk or selectively into the structures after all layers have been
formed.
[0104] As a further example, in other embodiments, it may be
desirable to have a structure composed of more than one conductive
material (e.g. nickel and gold or copper and gold) and as such the
process variations may be implemented to accomplish this
result.
[0105] Some preferred embodiments of the invention provide
microminiature RF or microwave transmission lines. Such
transmission lines may be used as building blocks for RF and
microwave components. A preferred transmission line has a
rectangular coaxial structure that includes a rectangular
solid-metal center conductor and a solid metal outer conductor.
When used herein, a microminiature coaxial component or line shall
mean a component having a minimum cross-sectional dimension from
one inside wall of the outer conductor to the opposite inside wall
of the outer conductor is less than about 200 .mu.m. Coaxial
transmission line is well suited to such microminiaturization
because it supports a transverse electromagnetic (TEM) fundamental
mode. From fundamental electromagnetic theory, a TEM mode is known
to have a zero cut-off frequency. So the TEM mode continues to
propagate at any practical frequency no matter how small the
dimensions of the structure.
[0106] Three benefits of microminiaturized coaxial line are size,
microwave bandwidth, and phase linearity. In general, the physical
length of passive transmission-line components must be of the order
of one free-space wavelength at the operating frequency which is,
for example, 30 cm at 1 GHz. With conventional coaxial transmission
line or waveguide, this results in a component having a linear
dimension of this order. With microminiature coaxial line, the
component can be made much shorter by wrapping the line back and
forth in a serpentine fashion and even by stacking the multiple
serpentine levels of the line.
[0107] A second benefit of microminiature coax is excellent
bandwidth performance. In any coaxial transmission line this is
defined maximally by the cut-on frequency of the first higher-order
mode, which is usually a transverse-electric (TE) mode. From
fundamental electromagnetics, it is known that this cut-on
frequency scales inversely with the largest dimension of the outer
conductor. In conventional coax this cut-on generally occurs
between 10 and 50 GHz. In microminiature coax this cut-on can
easily be extended to well above 100 GHz, giving it the bandwidth
to handle the highest frequencies in near-term analog systems and
the sharpest pulses in digital systems.
[0108] A third benefit of microminiature coax is its degree of
phase linearity. From fundamental electromagnetics, it is known
that the TEM mode is the only mode on a transmission line that can
propagate with zero dispersion. In other words, all frequencies
within the operational bandwidth have the same phase velocity, so
the dependence of relative phase between two arbitrary points on
the line is perfectly linear with frequency. Because of this
property, sharp non-sinusoidal features, such as sharp digital
edges or short digital pulses propagate without distortion. All of
the other known transmission line media at the size scale of
microminiature coax (i.e., less than 200 .mu.m) do not propagate a
pure TEM mode but rather a quasi-TEM mode. A good example is the
strip line commonly used in Si digital ICs or the microstrip
commonly used in GaAs or InP MMICs (monolithic microwave integrated
circuits).
[0109] Beside the dimension, another feature of some preferred
microminiature coaxial lines is their rectangular shape
cross-sectional shape. Conventional coaxial lines are generally
made of circular center and outer conductors because of the
relative simplicity in fabricating a circular shape (e.g., round
wire) for the center conductor and a hollow tube (e.g., catheter)
as the outer conductor. Fundamental electromagnetic theory shows
that rectangular coax can provide very similar performance to
circular coax, although analytic methods of design are lacking.
Fortunately, numerical tools (e.g., high-frequency structure
simulator, or HFSS, software) are now readily available which can
aid in the design of components such as rectangular microminiature
coax of any shape or size.
[0110] In some preferred embodiments microminiature coaxial line is
used in producing ultra-compact microwave components by, at least
in part, utilization of the electrochemical fabrication techniques
and particularly electrochemical fabrications techniques using
conformable contact masks. There is an entire family of passive
microwave functions that can not be realized in semiconductor ICs,
or that can be realized only with a significant penalty in
performance. A good example of a function that cannot be realized
on a semiconductor IC is circulation--i.e., the nonreciprocal
transmission of microwave power between neighboring ports around a
loop. An example of a function with inferior IC performance is
frequency multiplexing--i.e., the routing of microwave power from
one input port into a number of different output ports depending on
frequency. Microminiature coaxial lines may be used in forming
components that can provide such functionality particularly when
combined with the versatility of electrochemical fabrication
processes.
[0111] In some preferred embodiments, microminiature coaxial line
is integrated with active semiconductor devices, particularly RF
and high-speed digital ICs. Such integration addresses a growing
problem in the IC industry which is the interconnecting and routing
of high-frequency analog and digital signals within chips. A good
example of where such integration would be useful is in clock
distribution in high speed microprocessors. Transmission of very
sharp edges down conventional (stripline) transmission lines on Si
invariably distorts, or spreads out, the edge because of dispersion
and losses on the line. With microminiature coaxial lines, the
clock signal could be coupled immediately into a single-mode
coaxial structure in which the fundamental and all Fourier
components of the clock pulse would propagate for long distances
with the same velocity. As such, the clock pulse distortion, and
associated clock skew, could be mitigated.
FIGS. 4A-4C illustrate an RF/microwave filter 102 of an embodiment
of the present invention. FIG. 4A depicts a perspective view of a
coaxial filter element including a first set 104 of spokes
104a-104d. FIG. 4B depicts a plan view of filter 102 as viewed from
lines 4(b)-4(b) of FIG. 4A. FIG. 4C depicts a plan view of the
coaxial filter along lines 4(c)-4(c) of FIG. 4A. FIG. 4C
illustrates that the filter of FIG. 4A includes three sets of
spokes spaced apart by one-half (1/2) of the wavelength
(.lamda..sub.o) of an approximately central frequency in a band of
frequencies that will be passed by the filter. In this
configuration, the filter may be considered a Bragg-type filter
having 2 poles (each adjacent pair of sets forming a single pole).
In one example, the filter can take on the dimensions set forth in
TABLE 1.
TABLE-US-00001 TABLE 1 Reference Dimension Reference Dimension
Reference Dimension 122 520 .mu.m 124 400 .mu.m 126 520 .mu.m 128
400 .mu.m 130 116 .mu.m 132 116 .mu.m 134 180 .mu.m 136 168 .mu.m
138 40 .mu.m 140 168 .mu.m 142 40 .mu.m 144 180 .mu.m 146 60 .mu.m
148 60 .mu.m 150 40 .mu.m 152 40 .mu.m 154 40 .mu.m 156
.lamda..sub.o/2 158 .lamda..sub.o/2
[0112] In other embodiments the dimensions may be varied to change
the insertion loss of the filter in the pass band, the attenuation
in the stop band, and the characteristics in the transition region.
In other embodiments various parameters may also be modified by
varying the material or materials from which the filter and/or
filter components are made. For example, the entire filter may be
formed from nickel or copper, or it may be partially or entirely
plated with silver or gold.
[0113] FIG. 5 depicts a plan view of the central portion of a
coaxial filter of an alternative embodiment where the filter
contains five sets of spokes 160a-160e (two spokes per set are
depicted in this view) each spaced at about one-half the central
frequency of the pass band (i.e. 162, 164, 166, and
168=.lamda..sub.o/2). This figure illustrates a four pole
embodiment.
[0114] In alternative embodiments other numbers of poles may be
used in forming the filter (e.g. three poles or five or more
poles).
[0115] FIG. 6A depicts end views of a rectangular filter that uses
multiple sets of spokes with four spokes per set. In one example,
the filter can take on the dimensions set forth in TABLE 2.
TABLE-US-00002 TABLE 2 Reference Dimension Reference Dimension
Reference Dimension 222 920 .mu.m 224 800 .mu.m 226 320 .mu.m 228
200 .mu.m 230 316 .mu.m 232 59 .mu.m 234 80 .mu.m 236 88 .mu.m 238
40 .mu.m 240 168 .mu.m 242 76 .mu.m 244 362 .mu.m 246 60 .mu.m 248
60 .mu.m
[0116] As with the square coaxial filter of FIGS. 4A-4C, the
dimensions set forth above for the rectangular coaxial filter may
be varied. In the most preferred embodiments of this rectangular
filter the sets of spokes are spaced at about .lamda..sub.o/2.
[0117] FIGS. 6B and 6C illustrate examples of two alternative
cross-sectional configurations for coaxial filters of the type
illustrated (i.e. a circular configuration and an elliptical
configuration, respectively). In other embodiments other
cross-sectional configurations are possible and even the
cross-sectional configurations of the inner conductors 302 and 302'
may be different from that of the outer conductors 304 and 304'. In
still other embodiments the spokes may take on different
cross-sectional configurations (square, rectangular, circular,
elliptical, and the like).
[0118] FIGS. 7A-7D depict examples of alternative spoke
configurations that may be used in coaxial filters. FIG. 7A
illustrates an embodiment where only two spokes 312 and 314 are
used and extend in the longer cross-sectional dimension of the
rectangular outer conductor 316 and maintain the symmetry of the
configuration. FIG. 7B illustrates a similar two spoke embodiment
to that of FIG. 7A with the exception that the spokes 322 and 324
extend in smaller cross-sectional dimension of the outer conductor
326. FIG. 7C illustrates an embodiment where two spokes are still
used as in FIGS. 7A and 7B where one spoke 332 extends in the
horizontal dimension (i.e. the major dimension of the rectangular
outer conductor 336) and one spoke 334 extends in the vertical
dimension (i.e. the minor dimension of the rectangular outer
conductor 336). In FIG. 7D only a single spoke 342 makes up each
set.
[0119] As an example, the embodiment of FIG. 7A may take on the
dimensions set forth in TABLE 2 above with the exception of
dimensions 242, and 244 that do not exist in this configuration. As
another example, the embodiment of FIG. 7A may take on the
dimensions set forth in TABLE 3 where the reference numerals have
been modified to include apostrophes.
TABLE-US-00003 TABLE 3 Reference Dimension Reference Dimension
Reference Dimension 222' 720 .mu.m 224' 600 .mu.m 226' 420 .mu.m
228' 300 .mu.m 230' 175 .mu.m 232' 87 .mu.m 234' 130 .mu.m 236' 125
.mu.m 238' 40 .mu.m 240' 250 .mu.m 246' 60 .mu.m 248' 60 .mu.m
[0120] In alternative embodiments, other spoke numbers (e.g. three
or five) and configurations (e.g. multiple spokes extending from a
single side of the conductor, not all spokes extending radically
outward from the inner conductor to the outer conductor) may
exist.
[0121] FIGS. 8A and 8B illustrate perspective views of non-liner
coaxial filter components according to other embodiments of the
invention. FIG. 8A depicts an extended serpentine shape while FIG.
8B depicts a spiraled configuration. In still other alternative
embodiments other configurations may be used that take an entry and
exit port out of the plane of the winding structure or even cause
the winding in general to be stacked or extend in three-dimensions.
Such three dimensional stacking may lead to more compact filter
designs than previously obtainable.
[0122] FIGS. 9A-9C depict alternative embodiments of coaxial filter
components that use a combination of spokes and either protrusions
along the inner or outer conductor to aid in filtering RF or
microwave signals. In particular FIG. 9A illustrates an embodiment
where spokes 352, 354, 356, and 358 are included at the end of the
outer conductor 362 while intermediate to the ends of the outer
conductor protrusions 372, 374, 376, and 378 are included on the
interior surface of the outer conductor and are preferably about
one-quarter of the wavelength (.lamda.o/4) in length and spaced by
about one-half the wavelength (.lamda.o/2). In alternative
embodiments, the recesses in the outer conductor 362 may be
considered as opposed to protrusions. In the embodiment of FIG. 9A
the spokes are not spaced from each other by .lamda.o/2 as in
previous embodiments but instead are spaced by an integral multiple
of .lamda.o/2. In the embodiment depicted the integral multiple is
three.
[0123] FIG. 9B illustrates another alternative embodiment where the
spacing between spokes are a non unity integral multiple of
.lamda.o/2 and at the intermediate .lamda.o/2 positions protrusions
382, 384, 386, and 388 (of length approximating .lamda.o/2) are
included on the inner conductor 392.
[0124] FIG. 9C illustrates a third alternative embodiment where not
only are protrusions included on the inner conductor but an
additional intermediate set of spokes 394 and 396 is also included.
The most preferred spacing between each successive set of filter
elements remains approximately .lamda.o/2.
[0125] In further embodiments other configurations of spokes,
protrusions, and/or indentations are possible. In some embodiments,
it may be acceptable to space the successive filter elements (e.g.
spokes, protrusions, and/or indentations) at integral multiples of
.lamda.o/2.
[0126] In the embodiments of FIGS. 4A-9D, the spokes provided in
the structures may provide sufficient support for the inner
conductor such that no dielectric or other support medium is
needed. As such, in the most preferred embodiments the inner
conductor is separated from the outer conductor by an air gap or
other gaseous medium or by an evacuated space. In other embodiments
a solid or even liquid dielectric material may be inserted
partially within or completely within the gap between the inner and
outer conductors. The insertion of the dielectric may occur after
formation of the conductors or may be formed in situ with the
formation of the conductors. Various example implementation
processes will be discussed hereafter.
[0127] FIG. 9D depicts a plan view of the central portion, along
the length, of a serpentine-shaped two pole coaxial filter. In this
embodiment no spokes are used but only protrusions 394, 396, and
398 on the inner conductor 392' are used to provide the filtering
effect. In alternative embodiments protrusions on the inside of
portion of the outer conductor 362' may be used or a combination of
protrusions on the inside and outside conductor may be used. As no
spokes are used, the inner conductor's position is not fixed
relative to the outer conductor. Various embodiments will be
discussed hereafter that will allow for the formation of a
dielectric between the inner and outer conductors during build up
of the conductive materials. Various other embodiments will also be
discussed that allow for the transition from a conductive support
used during layer-by-layer build up to a complete or partial
formation of a solid dielectric in between the inner and outer
conductors.
[0128] FIGS. 10A-10D depict plan views of the central portion,
along the length of coaxial elements that include sharp transitions
in direction of radiation propagation. According to the production
methods of the present invention miter bends of varying degrees can
be inserted into coaxial components as well as waveguide components
with little concern for the geometric complexity of the design or
for the accessibility of tooling to reach the locations to be
mitered. FIG. 10A depicts transitions from one coaxial segment 402
to another coaxial segment 404 and then again to another coaxial
segment. In this Figure the transitions 412, 414, 416, 418, 422,
424, 426, and 428 are shown as 90.degree. transitions and it is
anticipated that significant reflection could result from these
sharp turns. FIG. 10B illustrates the use of mitered facets 432 and
434 at transitions 412''' and 414''' to help reduce the losses
(e.g. reflections). FIG. 100 depicts mitered facets for all
transitions 412', 414', 416', 418', 422', 424', 426', and 428'
which are believed to help further reduce losses. In still further
embodiments the facet length can be extended (e.g. the lengths of
the facets at 412 and 414) to ensure that a larger portion of the
impinging radiation strikes with a non-90.degree. incident angle.
FIG. 10D illustrates that multiple facets may be applied to each
transition region 412'', 414'', 416'', 418'', 422'', 424'', 426'',
and 428''. The mitering effects according to the present production
methods are not only applicable to coaxial components (e.g.
transmission lines, filters, and the like) but are also applicable
to waveguides (e.g. waveguides with internal dimensions under 800
.mu.m, under 400 .mu.m, or even with smaller dimensions, or larger
waveguides where propagation paths are complex and monolithic
structures are desired to reduce size and or assembly
difficulties).
[0129] FIGS. 11A and 11B depict, respectively, plan views along the
central portions of a coaxial transmission line 438 and a coaxial
filter component 440 where perturbations 436 are included on the
inside surface of the smaller radius side of the coaxial line. The
perturbations may be smooth and wave-like or they may be of a more
discontinuous configuration. It is intended that the perturbations
increase the path length along the side having the smaller nominal
radius such that the path length is closer to that of the path
length along the outer wall then it would be if the surface having
the smaller nominal radius were a simple curve 442. In alternative
embodiments the central conductor may also be modified with path
length perturbations.
[0130] FIGS. 12A-12C depict a coaxial three-pole stub-based filter
of an alternative embodiment of the invention. FIG. 12A depicts a
plan view (from the top) of the central portion, along the length
of the filter. FIG. 12(b) depicts an end view of the filter of FIG.
12A illustrating the rectangular configuration of the structure.
FIG. 12C depicts a plan view of a circular version of the filter of
FIGS. 12A and 12B. In one example, the filter of FIGS. 12A-12C can
take on the dimensions set forth in TABLE 4.
TABLE-US-00004 TABLE 4 Reference Dimension Reference Dimension
Reference Dimension 502 300 .mu.m 504 300 .mu.m 506 25 .mu.m 508-S0
245 .mu.m 508-S1 165 .mu.m 508-S2 25 .mu.m 512 .lamda..sub.o/4 514
.lamda..sub.o/4 516 .lamda..sub.o/4 (250 mm) (250 mm) (250 mm) 522
3.00 mm 524 1.64 mm 526 200 .mu.m 528 100 .mu.m
[0131] Each pair of stubs 522 and 524 provide a capacitive and an
inductive reactance, respectively, whose combination provides a
pole of the filter. Each stub is shorted to the outside conductor
556 at the end of its side channel 552 and 554 respectively. The
spacing between the poles preferably approximates one-quarter of
the wavelength (.lamda..sub.o/4) of the central frequency of the
desired pass band of the filter. The lengths of the stubs are
selected to provide a capacitive reactance (e.g. something longer
than .lamda..sub.o/4) and an inductive reactance (something shorter
than .lamda..sub.o/4). In alternative embodiments it is believed
that spacing between the poles may be expanded to an integral
multiple of .lamda..sub.o/4, other filtering elements may be added
into the component (e.g. spokes, protrusions, and the like).
[0132] In other embodiments the dimensions may be varied to change
the insertion loss of the filter in the pass band, the attenuation
in the stop band, and the characteristics in the transition region
as well as in the pass band regions. In this other embodiments
various parameters may also be modified by varying the material or
materials from which the filter and/or filter components are made.
For example, the entire filter may be formed from nickel or copper,
or it may be partially or entirely plated with silver or gold.
[0133] In alternative embodiments it may be possible to form each
pole from one shorted stub (providing a shunt inductance) and one
open stub (providing a shunt capacitance) that terminates short of
the end of the channel (e.g. into a dielectric) wherein the
capacitive stub may be able to be shortened due to its open
configuration.
[0134] FIG. 13 depicts a plan view (from the top) of the central
portion, along the length of an S-shaped two-pole stub based band
pass coaxial filter. Entry port 602 and exit port 604 are connected
by a passage 606 in outer conductor 608 from which two pairs of
channels 612 and 614 extend. Down the center of passage 606 an
inner conductor 616 extends and from which two pairs of stubs 622
and 624 extend until they short into the outer conductor 608 at the
ends of channels 612 and 614 respectively.
[0135] FIGS. 14A and 14B depict perspective views of coaxial filter
elements having a modified design that includes openings (e.g.
channels) along the length of the outer conductor where the
openings are not intended to provide radiation entry or exit ports.
In some of the production embodiments of the present invention such
openings can aid in the release of a structural material 702 from a
sacrificial material 704 that may have been deposited within the
small cavities and channels within the outer conductor. In certain
embodiments where chemical etching of the sacrificial material 704
is to occur, such holes may aid in allowing the etchant to get into
the small cavities and channels. In other embodiments where a
sacrificial material is to be separated from a structural material
by melting and flowing the opening may not be needed but if located
at selected locations (e.g. near the ends of blind channels and the
like) the openings may allow appropriately supplied pressure to aid
in the removal of the sacrificial material. FIG. 14A depicts a
perspective view of the component 706 formed from structural
material embedded in and filled by sacrificial material. FIG. 14B
depicts a perspective view of the component 706 separated from the
sacrificial material.
[0136] FIGS. 15A-15D illustrate plots of transmission versus
frequency according to mathematical models for various filter
designs discussed above. FIG. 15A depicts a modeled transmission
plot for a 2 pole filter (three sets of spokes) having a
configuration similar to that of FIG. 7A and made from nickel. The
dimensions of the component are set forth in Table 5. As can be
seen from the FIG. 15A the band pass of the filter is centered
around 28 GHz with an insertion loss of about 20-22 dB in the pass
band and an insertion loss in the stop band ranging from about
61-77 dB.
TABLE-US-00005 TABLE 5 Feature Dimension Inside width of the outer
conductor 600 .mu.m Inside Height of the outer conductor 300 .mu.m
Width of the central (i.e. inner) conductor 250 .mu.m Height of the
central (i.e. inner) conductor 75 .mu.m Height of the horizontally
extending spokes 40 .mu.m Thickness (i.e. dimension into the page)
of the 100 .mu.m horizontally extending spokes Spacing between
successive sets of spokes ~5-5.5 mm
[0137] FIG. 15B depicts a model transmission plot for a 2 pole
filter (three sets of protrusion on the inner conductor) as shown
in FIG. 9D where the length of each protrusion is approximately
.lamda..sub.o/4 and the center-to-center spacing of the protrusions
is approximately .lamda..sub.o/4 having a configuration similar to
that of FIG. 7A and made from nickel. The inside diameter of the
outer conductor is about 240 .mu.m, the diameter of the central
conductor transitions between 20 .mu.m and 220 .mu.m with the
protrusions having a length of about 15 mm and a center-to-center
spacing of about 30 mm. From FIG. 15B the band pass is centered
around 5 GHz with an insertion loss of 5-6 dB and an insertion loss
in the stop band of about 13-18 dB.
[0138] FIGS. 15C and 15D depict model transmission plots for
filters configured according to structures and dimensions for FIGS.
12A-12C where the structural material is nickel for FIG. 15C and is
gold plated nickel for FIG. 15D. FIG. 15C indicates an insertion
loss on the order of 7-8 dB in the band pass region while FIG. 15D
indicates a corresponding 1-2 dB insertion loss.
[0139] FIG. 16 provides a flow chart of an electrochemical
fabrication process that builds up three-dimensional structures
from a single conductive material and a single dielectric material
that are deposited on a layer-by-layer basis.
[0140] The process of FIG. 16 begins with block 702 where a current
layer number, n is set to a value of 1. The formation of the
structure/device will begin with layer 1 and end with a final
layer, N.
[0141] After setting the current layer number, the process moves
forward to decision block 704 where an inquiry is made as to
whether or not the surface of the substrate is entirely conductive
or at least sufficiently conductive to allow electrodeposition of a
conductive material in desired regions of the substrate. If
material is only going to be deposited in a region of the substrate
that is both conductive and has continuity with a portion of the
substrate that receives electrical power, it may not be necessary
for the entire surface of the substrate to be conductive. In the
present embodiment, the term substrate is intended to refer to the
base on which a layer of material will be deposited. As the process
moves forward the substrate is modified and added to by the
successive deposition of each new layer.
[0142] If the answer to the inquiry is "yes", the process moves
forward to block 708, but if the answer is "no" the process first
moves to block 706 which calls for the application of a seed layer
of a first conductive material on to the substrate. The application
of the seed layer may occur in many different ways. The application
of the seed layer may be done in a selective manner (e.g. by first
masking the substrate and then applying the seed layer and
thereafter removing the mask and any material that was deposited
thereon) or in a bulk or blanket manner. A conductive layer may be
deposited, for example, by a physical or chemical vapor deposition
process. Alternatively it may take the form of a paste or other
flowable material that can be solidified or otherwise bonded to the
substrate. In a further alternative it may be supplied in the form
of a sheet that is adhered or otherwise bonded to the substrate.
The seed layer is typically very thin compared to the thickness of
electrodeposition that will be used in forming the bulk of a layer
of the structure.
[0143] After application of the seed layer, the process moves
forward to block 708 which calls for the deposition of a second
conductive material. The most preferred deposition process is a
selective process that uses a dielectric CC mask that is contacted
to the substrate through which one or more openings exist and
through which openings the conductive material can be
electrodeposited on to the substrate (e.g. by electroplating).
Other forms of forming a net selective deposit of material may also
be used. In various alternatives of the process, the first and
second conductive materials may be different or they may be the
same material. If they are the same the structure formed may have
more isotropic electrical properties, whereas if they are different
a selective removal operation may be used to separate exposed
regions of the first material without damaging the second
material.
[0144] The process then moves forward to block 710 which calls for
removing the portion of the seed layer that is not covered by the
just deposited conductive material. This is done in preparation for
depositing the dielectric material. In some embodiments, it may be
unnecessary to remove the seed layer in regions where it overlays
the conductive material deposited on an immediately preceding layer
but for simplicity in some circumstances a bulk removal process may
still be preferred. The seed layer may be removed by an etching
operation that is selective to the seed layer material (if it is
different from the second conductive material). In such an etching
operation, as the seed layer is very thin, as long as reasonable
etching control is used, little or no damage should result to the
seed layer material that is overlaid by the second conductive
material. If the seed layer material (i.e. the first conductive
material) is the same as the second conductive material, controlled
etching parameters (e.g. time, temperature, and/or concentration of
etching solution) should allow the very thin seed layer to be
removed without doing any significant damage to the just deposited
second conductive material.
[0145] Next the process moves forward to block 712 which calls for
the deposition of a dielectric material. The deposition of the
dielectric material may occur in a variety of ways and it may occur
in a selective manner or in a blanket or bulk manner. As the
process of the present embodiment forms planarized composite layers
that include distinct regions of conductive material and distinct
regions of the dielectric material, and as any excess material will
be planed away, it does no harm (other than that associated with
potential waste) to blanket deposit the dielectric material and in
fact will tend to offer broader deposition possibilities. The
deposition of the dielectric material may occur by spraying,
sputtering, spreading, jetting or the like.
[0146] Next, the process proceeds to block 714 which calls for
planarization of the deposited material to yield an nth layer of
the structure having desired net thickness. Planarization may occur
in various manners including lapping and/or CMP.
[0147] After completion of the layer by the operation of block 714,
the process proceeds to decision block 716. This decision block
inquires as to whether the nth layer (i.e. the current layer is the
last layer of the structure (i.e. the Nth layer), if so the process
moves to block 720 and ends, but if not, the process moves to block
718.
[0148] Block 718 increments the value of "n", after which the
process loops back to block 704 which again inquires as to whether
or not the substrate (i.e. the previous substrate with the addition
of the just formed layer) is sufficiently conductive.
[0149] The process continues to loop through blocks 704-718 until
the formation of the Nth layer is completed.
[0150] FIG. 17A depicts an end view of a coaxial structure 722 that
includes an outer conductive element 724, and inner conductive
element 726, an embedded dielectric region 728 and an external
dielectric region 730. In some embodiments that extend the process
of FIG. 16, it may be possible to use post-process (i.e. process
that occur after the deposition of all layers) operations to remove
a portion or all of the dielectric from region 730 and a portion or
all of the dielectric from region 728 under the assumption that
such removal from region 728 would be done in such away as to
ensure adequate support for the inner conductive element 726.
[0151] FIGS. 18A-18J illustrate application of the process flow of
FIG. 16 to form a structure similar to that depicted in FIGS. 17A
and 17B. FIGS. 18A-18J depict vertical plan views displaying a
cross-section of the structure as it is being built up
layer-by-layer. FIG. 18A depicts the starting material of the
process (i.e. a blank substrate 732 onto which layers will be
deposited). FIG. 18B depicts the resulting selectively deposited
second conductive material 734-1' for the first layer. In beginning
this process it was assumed that the supplied substrate was
sufficiently conductive to allow deposition without the need for
application of a seed layer. FIG. 18C illustrates the result of a
blanket deposition of the dielectric material 736-1' (according to
operation/block 712) while FIG. 18D illustrates the formation of
the completed first layer L1 as a result of the planarization
operation of operation/block 714. The first completed layer has a
desired thickness and distinct regions of conductive material 734-1
and dielectric material 736-1.
[0152] FIG. 18E illustrates the result of the initial operation
(block 706) associated with the formation of the second layer. The
application of a seed layer 738-2' was necessary for the second
layer as a significant portion of the first layer is formed of a
dielectric material and furthermore the center conductive region is
isolated from the two outer conductive regions. FIG. 18F
illustrates the result of the selective deposition of the second
conductive material 734-2' (operation 708) for the second layer and
further illustrates that some portions 738-2'' of the seed layer
738-2' are not covered by the second conductive material 734-2',
while FIG. 18G illustrates the result of the removal of the
uncovered portions of the seed layer 738-2'(operation 710) which
yields the net seed layer for the second layer 738-2. FIG. 18H
illustrates the result of the blanket deposition of the dielectric
material 736-2' for the second layer (operation 712). FIG. 18I
illustrates the completed second layer L2 that results from the
planarization process (operation 714) and that includes distinct
regions of conductive material 734-2 and dielectric material
736-2.
[0153] FIG. 18J illustrates the formation of the completed
structure from layers L1-L7. The operations for forming layers
L3-L7 are similar to those used during the formation of L2. The
structure device of FIG. 18J may be put to use or it may undergo
additional processing operations to prepare it for its ultimate
use.
[0154] Various alternatives to the embodiment of FIG. 16 are
possible. In one alternative, the order of deposition could be
reversed. In another process instead of depositing material
selectively, each material may be deposited in bulk, and selective
etching operations used to yield the "net" selective locating of
materials.
[0155] FIG. 19 provides a flow chart of an electrochemical
fabrication process that is somewhat more complex than the process
of FIG. 16. The process of FIG. 19 builds up three-dimensional
structures/devices using three conductive materials that are
deposited on a layer-by-layer basis. As all materials in this
process are conductors with the possible exception of the initial
substrate, a simplification of the layer formation process results
as compared to the process of FIG. 16. However, as three materials
may or may not be deposited on each layer, this process adds not
only complexity of the process but also can yield structures of
enhanced functionality and versatility.
[0156] The process starts with block 802 where a current layer
number is set to one (n=1). The process then moves to decision
block 804 where the inquiry is made as to whether the surface of
the substrate is entirely or at least sufficiently conductive. If
the answer to this inquiry is "yes" the process moves forward to
block 808. On the other hand if the answer is "no", the process
moves to block 806 which calls for the application of a seed layer
of a conductive material on to the substrate. The process then
loops to decision block 808.
[0157] In block 808, the inquiry is made as to whether or not a
first conductive material will be deposited on the nth layer (i.e.
on the current layer). If the answer to this inquiry is "no" the
process moves forward to block 812. On the other hand if the answer
is "yes", the process moves to block 810 which calls for the
selective deposition of the first conductive material. The process
then loops to decision block 812.
[0158] In block 812, the inquiry is made as to whether or not a
second conductive material will be deposited on the nth layer (i.e.
on the current layer). If the answer to this inquiry is "no" the
process moves forward to block 816. On the other hand if the answer
is "yes", the process moves to block 814 which calls for the
deposition of the second conductive material (which may be done
selectively or in bulk). The process then loops to decision block
816.
[0159] In block 816, the inquiry is made as to whether or not a
third conductive material will be deposited on the nth layer (i.e.
on the current layer). If the answer to this inquiry is "no" the
process moves forward to block 828. On the other hand if the answer
is "yes", the process moves to decision block 818.
[0160] In block 818 the inquiry is made as to whether or not a
second conductive material was deposited on the nth layer (i.e. on
the current layer). If the answer to this inquiry is "no" the
process moves forward to block 826. On the other hand if the answer
is "yes", the process moves to block 822 which calls for the
planarization of the partially formed layer at a desired level
which may cause an interim thickness of the layer to be slightly
more than the ultimate desired layer thickness for the final layer.
The process then moves to block 824 which calls for selectively
etching into the deposited material(s) to form one or more voids
into which the third material will be deposited. The process then
completes the loop to block 826.
[0161] Block 826 calls for the deposition of the third conductive
material. The deposition of the third conductive material may occur
selectively or in bulk. The process then loops to block 828.
[0162] Block 828 calls for planarization of the deposited materials
to obtain a final smoothed nth layer of desired thickness.
[0163] After completion of the formation of the nth layer by the
operation of block 828, the process proceeds to decision block 830.
This decision block inquires as to whether the nth layer (i.e. the
current layer) is the last layer of the structure (i.e. the Nth
layer), if so the process moves to block 834 and ends, but if not,
the process loops to block 832.
[0164] Block 832 increments the value of "n", after which the
process loops back to block 808 which again inquires as to whether
or not a first conductive material is to be deposited on the nth
layer. The process then continues to loop through blocks 808-832
until the formation of the Nth layer is completed.
[0165] FIGS. 20A and 20B depict perspective views of structures
that include conductive elements and dielectric support structures
that may be formed in part according to the process of FIG. 19. The
coaxial structure/device of FIG. 20A includes an outer conductor
842, an inner conductor 844, and dielectric support structures 846
that hold the two conductors in desired relative positions. During
formation, the inner and outer conductors are formed from one of
the three conductive materials discussed in relation to the process
of FIG. 19 (a primary material) and the outer conductor is formed
not only with entry and exit ports 848 and 850 but also with
processing ports 852. Within some of these processing ports a
secondary conductive material is located and which is made to
contact the inner conductor 844. In the remainder of the build
volume a tertiary conductive material is located. After formation
of all layers of the structure, the secondary conductive material
is removed and a dielectric material 846 is made to fill the
created void or voids. Thereafter, the tertiary conductive material
is removed leaving the hollowed out structure/device of FIG. 20A.
It should be understood that in the discussion of FIG. 20A, the
references to the primary, secondary, and tertiary materials do
correlate one-to-one with the first, second, and third conductive
materials of the process of FIG. 19 but not necessarily
respectively.
[0166] FIG. 20B depicts a similar structure to that of FIG. 20A
with the exception that the inner conductor and outer conductor
positions are more firmly held into position by modified dielectric
structures 846'.
[0167] FIGS. 21A-21T illustrate application of the process flow of
FIG. 19 to form a coaxial structure similar to that depicted in
FIG. 20A where two of the conductive materials are sacrificial
materials that are removed after formation of the layers of the
structure and wherein a dielectric material is used to replace one
of the removed sacrificial materials.
[0168] FIG. 21A depicts the starting material of the process (i.e.
a blank substrate 852 onto which layers will be deposited). In
moving through the process, it is assumed that the supplied
substrate was sufficiently conductive to allow deposition without
the need for application of a seed layer (i.e. the answer to the
inquiry of 804 was "yes") and that the answer to the inquiry of 808
was also "yes". FIG. 21B depicts the result of the operation of
block 819 related to the deposit of the first conductive material
854 for producing an initial deposition 854-1' for the first layer.
Next, it is assumed the answer to the inquiry of block 812 is "yes"
for the first layer. It is also assumed for the first layer that
the answer to the inquiry of block 816 is "no". As such FIG. 21C
illustrates the combined deposition of the second material 856
(block 810) and the planarization of the deposited first and second
conductive materials 854-1 and 856-1 (block 828) to complete the
formation of the first layer L1. FIGS. 21D and 21E represent the
same processes and operations as were applied to the formation of
the first layer for formation of the second layer L2 which is
composed of distinct regions 854-2 and 856-2 of first and second
conductive materials. FIGS. 21F and 21(g) represent the same
processes and operations as were applied to the formation of the
first and second layers for formation of the third layer L3 which
is composed of distinct regions 854-3 and 856-3 of first and second
conductive materials.
[0169] FIGS. 21H-21K illustrate the results of some of the
operations associated with forming the fourth layer L4 of the
structure/device. FIG. 21H depicts the result of the operation of
block 810 related to the deposit of the first conductive material
854 for producing an initial deposition 854-4'' for the fourth
layer. Next, it is assumed the answer to the inquiry of block 812
is "yes" for the fourth layer. It is also assumed for the fourth
layer that the answer to the inquiry of block 816 is "yes". As
such, FIG. 21I illustrates the combined deposition of the second
material 856 (block 810) and the planarization of the deposited
first and second conductive materials 854-4' and 856-4' (block 822)
to form a smooth but only partially formed fourth layer. FIG. 21J
illustrates the result of operation 824 in etching away a portion
of the planed deposit 856-4'. FIG. 21K illustrates the combined
results of operations 826 and 828 to yield the completed fourth
layer L4 which is composed of distinct regions 854-4 and 856-4, and
858-4 of first conductive material 854, the second conductive
material 856, and the third conductive material 858.
[0170] FIGS. 21L and 21M, FIGS. 21N and 21O, and 21P and 21Q
represent the same processes and operations as were applied to the
formation of the first three layers for formation of the fifth
through seventh layers (L5, L6, and L7) which are composed
respectively of distinct regions 854-5 and 856-5, 854-6 and 856-6,
and 854-7 and 856-7 of first and second conductive materials.
[0171] FIGS. 21R-21T represent an extension of the process flow of
FIG. 19. FIG. 21R represents the result of the selective removal
(e.g. by etching or melting) of the third conductive material to
form a void 866 that extends through an outer wall 862 of first
conductive material to contact an isolated interior structure 864
of the second conductive material (e.g. the inner conductor of a
coaxial transmission line). FIG. 21S depicts the structure of FIG.
21R with the void 866 filled by a selected dielectric material 860
which contacts both the outer wall 862 and the interior structure
864. FIG. 21T depicts the structure of FIG. 21S with the first
conductive material removed to yield a final substantially air
filled structure with the interior structure 864 supported relative
to the outer wall by one or more dielectric structures. FIG. 21T
also depicts an opening in the structure.
[0172] FIGS. 22A-22C depict application of the first removal, back
filling, and second removal operations to the opposite materials as
illustrated in FIGS. 21R-21T. In FIGS. 22A-22C the first conductive
material 854 is removed to create a void, the void is filled with a
dielectric 860', and then the third conductive material is
removed.
[0173] In alternative embodiments, the processes of FIGS. 21R-21T
and 22A-22C can be extended to include a second filling operation
to fill the void that results from the final removal operation. The
second filling operation may use the same or a different dielectric
than was originally used. In still further alternatives more than
three conductive materials may be used such that the resulting
structure/device is comprised of two or more conductive materials,
and/or is accompanied by two, three or more solid, liquid, or
gaseous dielectrics.
[0174] FIGS. 23A and 23B provide a flow chart of an electrochemical
fabrication process that builds up three-dimensional
structures/devices using two conductive materials and one
dielectric material.
[0175] The process of FIGS. 23A and 23B begins at block 902 with
the setting of three process variables: (1) the layer number is set
to one, n=1, (2) a primary seed layer parameter is set to zero,
PSLP=0, and (3) a second seed layer parameter is set to zero,
SSLP=0. The process then proceeds to decision block 904 where the
inquiry is made as to whether the surface of the substrate is
entirely or at least sufficiently conductive? If "yes" the process
proceeds to decision block 906 and if "no" the process proceeds to
block 908.
[0176] In blocks 906 and 908, the same inquiry is made as to
whether a first conductive material (FCM) will be deposited on the
nth layer (i.e. the first layer). If the answer to the inquiry of
block 906 is "yes", the process proceeds to block 914 and if it is
"no", the process proceeds to block 916. If the answer to the
inquiry of block 908 is "yes", the process proceeds to block 910
and if it is "no", the process proceeds to block 916.
[0177] Block 910 calls for application of a primary seed layer
(PSL) of a conductive material on to the substrate. This seed layer
may be applied in a variety of ways some of which have been
discussed previously herein. From Block 910 the process proceeds to
block 912 where the primary seed layer parameter is set to one,
PSLP=1, which indicates that a primary seed layer has been
deposited on the current layer.
[0178] From block 912 and from a "yes" answer from block 906 the
process proceeds to block 914 which calls for the selectively
deposition of the FCM. In some alternatives, the preferential
deposition is via a CC mask. From block 914, from a "no" answer in
block 908, and from a "no" answer in block 906 the process proceeds
to decision block 916.
[0179] In decision block 916 an inquiry is made as to whether a
second conductive material (SCM) will be deposited on the nth layer
(i.e. the first layer in this case). If the answer to the inquiry
of block 916 is "yes", the process proceeds to block 924 and if it
is "no", the process proceeds to block 918.
[0180] In blocks 924 and 918, the same inquiry is made as to
whether a primary seed layer has been deposited on the first layer
(i.e. Does PSLP=1 ?). If the answer to the inquiry of block 924 is
"yes", the process proceeds to block 926 and if it is "no", the
process proceeds to block 934. If the answer to the inquiry of
block 918 is "yes", the process proceeds to block 922 and if it is
"no", the process proceeds to block 966.
[0181] In decision block 926 an inquiry is made as to whether the
existence of the PSL is compatible with an SCM that will be
deposited. If the answer to the inquiry of block 924 is "yes", the
process proceeds to block 928 and if it is "no", the process
proceeds to block 932.
[0182] Blocks 932 and 922 call for the removal of any portion of
the PSL that is not covered by the FCM. From block 932 the process
proceeds to block 934, as did a "no" response in block 924, and
from block 922 the process proceeds to block 966. In decision block
934 an inquiry is made as to whether the surface of the substrate
is entirely or sufficiently conductive. Though this question was
asked previously, the answer may have changed due to a different
pattern of conductive material to be deposited or due to the
removal of a previously supplied seed layer because it is
incompatible with the second conductive material that is to be
deposited. If the answer to the inquiry of block 934 is "yes", the
process proceeds to block 928 and if it is "no", the process
proceeds to block 936.
[0183] Block 936 calls for application of a secondary seed layer
(SSL) which will allow a second conductive material to be deposited
in a subsequent operation. After which the process proceeds to
block 938 where SSLP is set to one, thereby indicating that the
present layer received the secondary seed layer which information
will be useful in subsequent operations.
[0184] Block 928 is reached by a "yes" response to either of block
926 or 934, or via block 938. Block 928 calls for the deposition of
the second conductive material (SCM). This deposition operation may
be a selective operation or a blanket operation.
[0185] From block 928 the process proceeds to decision block 942
where an inquiry is made as to whether a dielectric will be
deposited on the nth layer (i.e. the first layer). If the answer to
the inquiry of block 942 is "yes", the process proceeds to block
944 and if it is "no", the process proceeds to block 968.
[0186] Block 944 calls for planarizing the deposited materials to
obtain a partially formed nth layer having a desired thickness
which may be different from the final thickness of the layer. After
planarization the process proceeds to block 946 which calls for the
selectively etching into one or both of the deposited conductive
materials to form one or more voids into which the dielectric may
be located after which the process proceeds to block 948. If the
answer to the inquiry of block 948 is "yes", the process proceeds
to block 952 and if it is "no", the process proceeds to block
956.
[0187] Decision block 952 inquires as whether the etching of block
946 resulted in the removal of all exposed SSL? If the answer to
the inquiry of block 952 is "yes", the process proceeds to block
956 and if it is "no", the process proceeds to block 954.
[0188] Block 954 calls for the removal of the portion of the SSL
that is exposed by the voids formed in block 946. After the
operation of block 954, the process proceeds to decision block
956.
[0189] Decision block 956 inquires as whether PSLP is equal to one.
If the answer to the inquiry of block 956 is "yes", the process
proceeds to decision block 962 and if it is "no", the process
proceeds to block 966.
[0190] Decision block 962 inquires as to whether the etching of the
SCM removed all the exposed PSL. If the answer to the inquiry of
block 956 is "yes", the process proceeds to decision block 966 and
if it is "no", the process proceeds to block 964.
[0191] Block 964 calls for the removal of the portion of the PSL
that is exposed by the voids created in block 946. After the
operation of block 964 the process proceeds to block 966.
[0192] Block 966 calls for the deposition of the dielectric
material. The deposition process may be selective or of a blanket
nature and various processes are possible some of which were
discussed elsewhere herein.
[0193] Block 968 calls for planarization of the deposited materials
to obtain a final smoothed nth layer of desired thickness.
[0194] After completion of the formation of the nth layer by the
operation of block 968, the process proceeds to decision block 970
where PSLP and SSLP are both set to zero, after which the process
proceeds to decision block 972. This decision block inquires as to
whether the nth layer (i.e. the current layer) is the last layer of
the structure (i.e. the Nth layer), if so the process moves to
block 978 and ends, but if not, the process proceeds to block
974.
[0195] Block 974 increments the value of "n", after which the
process loops back to block 904 which again inquires as to whether
or not surface of the substrate (i.e. the substrate surface as
modified by the formation of the immediately preceding layer) is
sufficiently conductive. The process then continues to loop through
blocks 904-974 until the formation of the Nth layer is
completed.
[0196] As with the processes of FIGS. 16 and 19, various
alternatives to the process of FIGS. 23A and 23B exist. These
variations may involve changing the order of the material
depositions as a whole or changing the order of the operations for
performing each type of material deposition based on what other
operations have occurred or will occur during the formation of a
given layer. Additional materials of the conductive or dielectric
type may be added. Ultimate selectivity of any deposition may occur
by depositing material in voids, by actual control of the
deposition locations, or by etching away material after deposition.
Additional operations may be added to the process to remove
selected materials or to deposit additional materials.
[0197] FIG. 24 depicts a perspective view of a coaxial structure
that includes outer and inner conductive elements 1002 and 1004,
respectively, made from material 994 and a dielectric support
structure 1006 made from a material 996. The structure of FIG. 24
may be formed according to the process of FIGS. 23A and 23B with
the addition of a post layer formation operation that removes one
of the conductive materials. During layer-by-layer build up of the
structure, the inner and outer conductors are formed from one of
the two conductive materials discussed in relation to the process
of FIGS. 23A and 23B (i.e. a primary material). A secondary
conductive material is used as a sacrificial material. A dielectric
material (i.e. a tertiary material) is also used as part of the
structure. After formation of all layers of the structure, the
secondary conductive material is removed to yield the final
structure comprised of the primary conductive material 994 and the
dielectric material 996.
[0198] FIGS. 25A-25Z illustrate side views of the results of
various operations of FIGS. 23A and 23B that are used in forming
layers of the sample coaxial component illustrated in FIG. 24. The
operations associated with the results illustrated in FIGS. 25A-25X
and 26A-26F are set forth in the TABLE 6.
TABLE-US-00006 TABLE 6 FIGS. "25" FIGS. "26" Layers "L" Operation
Comments 25A, C, E, I, P, V 1, 2, 3, 4, 6, 7 914 The 1.sup.st
material 992 is deposited 26C 25B, D, F, X 1, 2, 6, 7 936 & 968
The 2.sup.nd material 994 is deposited and 26F planarized to
complete formation of the layer 25F, K, R 3, 4, 6 928 & 944 The
2.sup.nd material 994 is deposited and -- planarized to form an
incomplete layer 25G, L, S 3, 4, 6 946 The deposited material is
etched to form -- voids 990 25H, N U 3, 4, 6 966 & 968 The
3.sup.rd material 996 is deposited and -- planarized to complete
formation of the layer 25J, Q, W 4, 6, 7 936 A secondary seed layer
1000 is applied 26E -- A primary seed layer 998 is applied 26B 25M,
T 4, 6 Exposed portions of the secondary seed -- layer are removed
-- Exposed portions of the primary seed layer 26D are removed (o) 5
All operations performed for layer 4 --
[0199] FIG. 25Y illustrates an overview of the completed structure
with the presence of the layer delimiters removed and the under the
assumption that the second seed layer material was identical to the
second material. FIG. 25Z illustrates the result of a post process
1' material removal operation (e.g. selective etching) that yields
the structure illustrated in FIG. 24.
[0200] FIGS. 26A-26E illustrate an alternative to the process of
FIGS. 25H-25K when use of the primary seed layer is needed prior to
depositing the first conductive material for the fourth layer of
the structure.
[0201] FIG. 27 depicts a perspective view of a coaxial transmission
line. The coaxial transmission line 1002 includes an outer
conductive shield 1006 surrounding an inner conductor 1004. In the
illustrated embodiment, the transmission line 1002 may be set away
from a substrate 1008 by a spacer 1010. In the illustrated
embodiment the substrate may be a dielectric with an appropriate
ground potential being applied to the shield 1006 via conductive
spacer 1010 (e.g. via the underside of the substrate) while a
signal may be applied to the central conductor (e.g. via an
appropriate connection from the underside of the substrate). In
alternative embodiments, the shielding may curve around the bend in
the central conductor such that the shield provides substantially
complete shielding of the central conductor at substantially all of
its locations above the substrate (except for maybe one or more
openings in the shield that allows removal of a sacrificial
material that may have been used during device formation. In other
alternative embodiments, the substrate may be conductive with a
dielectric material providing isolation were the central conductor
and the interior portion of the coaxial element penetrates the
substrate. In still other embodiments, the shielding may take the
forms of a conductive mesh or even one or more conductive lines
that extend out of the plane of the substrate. In still other
embodiments, the transmission line may be curved in a single plane
(e.g. a plane parallel to that of the substrate) or it may take on
any desired three-dimensional pattern. For example, the
transmission line may take a spiraling pattern much like that of a
spiral loop of a conductive wire. Similarly, a filter element like
those shown in FIGS. 12C and 13 have be converted from the
relatively planar configurations shown to a more three dimensional
shape where, for example, the main line of the filter (616, 606)
takes form of spiral while branches 622, 614, and the like, either
take a path down the center of the spiral or take spiral path
themselves (e.g. a smaller diameter path than that taken by the
main line). Such a configuration can reduce the planar size of the
structure at the cost of increasing its height while still
maintaining a desired effective length.
[0202] FIG. 28 depicts a perspective view of an RF contact switch.
The RF switch is a cantilever switch. The switch 1022 includes a
cantilever beam 1026 which contacts a second beam 1024. The
cantilever beam deflects downwards due to electrostatic forces when
a voltage is applied between the underlying control electrode 1028.
In the illustrated embodiment, all of the switch elements are
suspended above the substrate with by pedestals 1030a-1030(c),
which, it is believed, will result in a reduction of parasitic
capacitance to the substrate. This approach makes it possible to
decrease the distance between the drive electrode and the
cantilever beam, which increases actuation force while decreasing
the required drive voltage, and at the same time allows increased
distance from the substrate, thereby reducing parasitics. This
independence of the electrode size and contact gaps is not possible
if both must lie on a planar substrate. The flexibility of the
multilevel embodiments of electrochemical fabrication makes it
possible to place the switch components in more optimal locations.
In one embodiment, the long cantilever beam may have a length of
about 600 .mu.m and a thickness of 8 .mu.m. A circular contact pad
may be located underneath the beam such that the contacts are
separated by, for example about 32 .mu.m for high isolation. The
lower beam may be suspended, for example, at about 32 .mu.m, above
the substrate while the upper beam may be about 88 .mu.m above the
substrate. Of course in other embodiments other dimensional
relationships may exist. In one example of the use of such a
switch, a voltage may be applied between control electrode 1028 and
cantilever 1026 to close the switch while an AC signal (e.g. an RF
or microwave signal) exists on either the cantilever or the other
beam and is capable of propagating once the switch is closed. In
some alternative designs, one or both of lines 1026 and 1024 may
include protrusions at their contact locations or alternatively the
contract locations may be made of an appropriate material to
enhance contact longevity. In still other alternative designs, the
entire switch may be located within a shielding conductor which
might reduce any radiative losses associated with signal
propagation along the lengths of lines 1024 and 1026. In still
further embodiments, the switch may be used as a capacitive switch
by locating a thin layer of dielectric (e.g. nitride) at the
contact location of one or both of lines 1024 and 1026 thereby
allowing the switch to move the contacts between low and high
capacitance values. Signal passage may occur for such a switch when
impedance matching occurs (e.g. when capacitance is low higher
frequency signals may pass while lower frequency signals may be
blocked or significantly attenuated. In still further embodiments
control electrode or the nearest portion of line 1026, thereto, may
be coated with a dielectric to reduce the possibility of a short
occurring between the control electrode and the deflectable line.
In still other embodiments, a pull up electrode may be included to
supplement separation of the contacts beyond what is possible with
the spring force of the deflectable line 1026 alone. In some
embodiments the ratio of switch capacitance (assuming it to be a
capacitive switch) when open to closed, is preferably greater than
about 50 and more preferably greater than about 100. In still other
embodiments, a secondary conductor may be attached to and separated
from the pedestal 1030(c) and the underside of line 1026 by a
dielectric. This secondary conductor may be part of the switch
control circuitry as opposed to having the control circuitry share
conductor 1026 with the signal.
[0203] FIG. 29 depicts a perspective view of a log-periodic
antenna. The antenna 1032 includes a number of different dipole
lengths 1034(a)-1034(j) along a common feedline 1036 that is
supported from a substrate (not shown) by spacer 1038). It is
believed that this elevated position may reduce parasitic
capacitive losses that may otherwise be associated with the antenna
contacting or being in proximity to a lossy substrate. In other
embodiments, other antenna configurations may be used, such as for
example, linear slot arrays, linear dipole arrays, helix antennas,
spiral antennas, and/or horn antennas.
[0204] FIGS. 30A-30B depict perspective views of a sample toroidal
inductor design rotated by about 180 degrees with respect to one
another. FIG. 30C depicts a perspective view of the toroidal
inductor of FIGS. 30A and 30B as formed according to an
electrochemical fabrication process. The toroidal inductor of FIG.
20C was formed according to the process of FIGS. 2A-2F. In some
embodiments the inductor may be formed on a dielectric substrate
while in other embodiments the inductor may be formed on a
conductive substrate with appropriate dielectrically isolated
feedthroughs. In one specific embodiment, the toroidal coil may
include 12 windings, be about 900 .mu.m across, and have its lower
surface suspended about 40 .mu.m above the substrate. The inductor
1042 includes a plurality of inner conductive columns 1044 and a
plurality of outer conductive columns 1046 connected by upper
bridging elements and lower bridging elements 1050(a) and 1050(b).
The inductor also includes two circuit connecting elements 1048(a)
and 1048(b) that are supported by spacers 1052(a) and 1052(b). In
some embodiments, the entire inductor may be supported by and
spaced from a substrate by the spacers 1052(a) and 1052(b). It is
believed that such spacing may reduce parasitic capacitance that
might otherwise result from contact between or proximity of the
lower conductive bridges 1050(b) and a substrate (not shown).
Though in some embodiments, the inner and outer conductive columns
may have similar dimensions, in the illustrated embodiment, the
area of each of the inner conductive columns is smaller than the
area of the outer conductive columns (e.g. the diameter is
smaller). Similarly, in the present embodiment the width of the
conductive bridges 1050(a) and 1050(b) also increase radially
outward from the center of the inductor. It is believed that such a
configuration will result in reduced ohmic resistance has a desired
current travels around the inductive path. It is also believed that
such a configuration may lead to reduced leakage of magnetic flux
from the inductor and thus contribute to an enhancement in
inductance or a reduction in noise that the component may radiate
to other circuit elements. In still further embodiments, it may be
advantageous to shield the outer circumference of the inductor by a
conductive wall. Similarly the inner circumference may also be
shielded by a conductive wall, and in still further embodiments the
upper surface and potentially even the lower surface may also be
shielded by conductive plates or meshes. In some alternative
embodiments the spacers 1052(a) and 1052(b) and even the circuit
connecting elements 1048(a) and 1048(b) may be shielded, at least
in part, by conductive elements which may help minimize radiative
losses. In further embodiments loops of the inductor may take on a
more circular shape as opposed to the substantially rectangular
shape illustrated.
[0205] FIGS. 31A-31B depict perspective views of a spiral inductor
design and a stacked spiral inductor formed according to an
electrochemical fabrication process, respectively. The illustrated
inductor 1062 includes eight coils 1064(a)-1064(g), one connecting
bridge 1066, and two spacers 1068(a) and 1068(b). In one detailed
embodiment, the coils may be about 8 .mu.m thick each, they may
have an outer diameter of about 200 .mu.m, they may be separated by
about 8 .mu.m, and the bottom coil may be elevated about 56 .mu.m
above the substrate. As with the illustrated embodiments of FIGS.
27-30C, the spacers are used not only for establishing an
electrical connection between the inductor and the rest of the
circuit but also to space the inductor coils from a substrate (not
shown).
[0206] FIG. 31C depicts a variation of the inductors of FIGS. 31A
and 31B. The inductor 1072 of FIG. 31C may be formed with the
indicated design features using 23 layers. As depicted, the
inductor includes 11 coil levels 1074(a)-1074(k) and 91/8 turns.
Each coil level is formed from an 8 micron thick layer and is
separated from other coil levels by gaps of 4 micron thickness. The
inner diameter is 180 microns and outer is 300 micron. As
illustrated the inductor includes a core which is 60 micron in
diameter with a 60 micron space between the core 1076 and windings
1074(a)-1074(k). A simple calculation based on a uniform magnetic
field yields an inductance of 20 nH for the inductor when the core
is disregarded. However since the real inductor has a diameter
larger than its length, and the windings are not particularly
tight, the inductance will be lower than this theoretical value.
The real value is estimated to be in the range of 25%-50% of the
theoretical value, (i.e. about 5-10 nH). On the other hand, the
inductance may be greatly enhanced by the presence of the core 1076
(e.g. by a factor of 100 or more). Of course, in other embodiments,
other configurations are possible.
[0207] In other embodiments, the inductors of FIGS. 31A-31C may
take on different forms. FIGS. 32A and 32B contrast two possible
designs where the design of FIG. 32B may offer less ohmic
resistance than that of FIG. 32A along with a possible change in
total inductance. A single inductor 1082 having N coils and a
relative long connector line 1084 is illustrated in FIG. 32A while
FIG. 32B depicts two half sized inductors 1086(a) and 1086(b) where
the number of coils in each is considered to be about one-half of
those in the inductor of FIG. 32A connected in series via short
bridging element 1088. As illustrated since bridging element 1088
is shorter than connector line 1084, it is believed that the
inductor pair of FIG. 32B will have less loss than that of FIG.
32A. On the other hand as the coupling between the two inductors is
probably reduced, there is probably an associated loss of net
inductance. By inclusion of a core that extends in the form of a
loop through both inductors it may be possible to bring the
inductance back up to or even beyond that of the taller inductor of
FIG. 32A.
[0208] FIGS. 33A and 33B depict a schematic representation of two
alternative inductor configurations that minimize ohmic losses
while maintaining a high level of coupling between the coils of the
inductor. In the figures the upward path of the coils is depicted
with a solid line while the downward path of the coils is depicted
with a dashed line. In FIG. 33A the upward extending coils have a
larger perimeter than the downward extending coils. In FIG. 33B
they are of substantially similar perimeter dimensions.
[0209] FIG. 34 depicts a perspective view of a capacitor 1092
including 12 interdigitated plates (two sets 1094(a) and 1094(b) of
six plates each). In a detailed embodiment each plate may have an
eight micron thickness, a 4 micron gap between each plate, and each
plate may be 436 .mu.m on a side. Based on these details, the
capacitance is calculated at about 5 pF based on an ideal parallel
plate calculation. It is anticipated that the value will be
somewhat different due to fringe field effects. As illustrated, the
capacitor is surrounded by a dam 1096 which may be used to
facilitate a post-release dielectric backfill while minimizing
dielectric spill over to adjacent devices that may be produced
nearby on the same substrate. Backfilling with a dielectric could
dramatically increase the capacitance offered by such capacitors.
Similarly decreasing the separation between plates and or adding
additional plates may also significantly increase the capacitance.
The capacitor is shown with two pairs of orthogonally located bond
pads 1098(a) and 1098(b), respectively. As the parallel bond pads
are conductively connected, electrical connection to the device may
occurred via connection to one of the 1098(a) pads and one of the
1098(b) pads. As illustrated the bond pads are in line with the
lowest plates of the capacitor and the upper plates are connected
to the lowest plates by columns located in the extended regions
from each group. In other embodiments, the pads could connect more
directly to, for example, the mid-level plates of each stack. The
current flow could from there proceed both upward and downward to
the other plates of each stack respectively.
[0210] FIGS. 35A and 35B depict a perspective view and a side view,
respectively, of an example of a variable capacitor 1102. The
capacitor plates have a similar configuration to that of FIG. 34
and are again divided into two sets of six plates 1104(a) and
1104(b). In this embodiment one set of capacitor plates 1104(a) is
attached to spring elements 1106 and to two sets of parallel plate
electrostatic actuators 1108 that can drive plates 1104(a)
vertically relative to fixed plates 1104(b). In use a DC potential
may be applied between spring supports 1110 and actuator pads 1112.
Actuator pads 1112 connect to columns 1114 which in turn hold fixed
drive plates 1116. When such a drive voltage is applied moveable
drive plates 1118 are pulled closer to fixed drive plates which in
turn pull moveable capacitor plates 1104(a) closer to fixed
capacitor plates 1104(b) via support columns 1124 and thereby
change the capacitance of the device. Capacitor plates 1104(b) are
held in position by support columns 1126. The capacitor may be
connected in a circuit via spring support 1110 and one of fixed
capacitor plate contact pads 1128.
[0211] In still further embodiments, resistive losses associated
with current carrying conductors such as the spacers of FIGS.
27-31C, with central conductors of coaxial components, and with
elements of various other components may be reduced by increasing
the surface area of the elements without necessarily increasing
their cross-sectional dimensions. It is believed that this can be
particularly useful when the frequency of the signal makes the skin
depth small compared to the cross-sectional dimensions of the
components. For example, a cross-sectional dimension of a current
carrying conductor (in a plane perpendicular to the direction of
current flow) could be increased by changing it from a circular
shape to a square shape or other shape containing a plurality of
angles. Two further examples of such coaxial elements are shown in
FIGS. 36A and 36B wherein coaxial elements 1132 and 1142,
respectively include central conductors 1134 and 1144 which have
been modified from a square and circular configuration to modified
configurations with indentations so as to increase their surface
areas.
[0212] FIG. 37 depicts a side view of another embodiment of the
present invention where an integrated circuit 1152 is formed on a
substrate 1154 (e.g. silicon) with contact pads 1156 exposed
through a protective layer 1158 located on the top of the
integrated circuit. The contact pads may be pads for connection to
other devices or alternatively may be pads for top side
intra-connection for linking separate parts of the integrated
circuit. For example, the intraconnects (and inter-connects) may be
pads for distributing high frequency clock signals (e.g. 10 GHz) to
different locations within the integrated circuit via a low
dispersion transmission line such as a coaxial capable or
waveguide. Two coaxial transmission lines 1162 and 1172 are
illustrated as connecting some of the pads to one another. The
outer conductors of the coaxial lines are supported by stands or
pedestals 1164 and 1174 and the connections to the pads are made by
wires 1166 and 1176. In alternative embodiments the connections to
the pads may be made by not only the wires but also by bring at
least a portion of the coaxial shielding in contact with or into
closer proximity with the surface of the integrated circuit. In
some embodiments, the coaxial structures may be supported by the
central wires and any grounding connections only while in other
embodiments pedestals or the like may be used. In some
implementations coaxial structures may be preformed and picked and
placed at desired locations on the integrated circuits or
alternatively the EFAB process may be performed directly onto the
upper surface of the integrated circuit. Some implementations of
such microdevice to IC integration are set forth in U.S.
Provisional Patent Application No. 60/379,133 which is described
briefly hereafter and is incorporated herein in its entirety. Of
course in other embodiments some pads may be for connection between
components of the IC while some other pads may be for connections
to other components.
[0213] FIGS. 38A and 38B illustrate first and second generation
computer controlled electrochemical fabrication systems (i.e.
EFAB.RTM. Microfabrication systems) produced by Microfabrica. These
systems may be used in implementing the processes set forth herein
and in forming devices/structures set forth herein. As presently
configured these systems include selective deposition and blanket
deposition stations, a planarization station, various cleaning and
surface activation stations, inspection stations, plating bath
circulation subsystems, atmosphere control systems (e.g.
temperature control and air filtering system), and a transport
stage for moving the substrate relative to the various stations
(i.e. for providing Z, X, and Y motion). Other systems may include
one or more selective etching stations, one or more blanket etching
stations, one or more seed layer formation stations (e.g. CVD or
PVD deposition stations), selective atmosphere control systems
(e.g. for supplying specified gases globally or within certain work
areas), and maybe even one or more rotational stages for aligning
the substrate and/or selected stations.
[0214] In some embodiments, it is possible to build a number of
similar components on a single substrate where the multiple
components may be used together on the substrate or they may be
diced from one another and applied to separate secondary substrates
as separate components for use on different circuit/component
boards. In other embodiments the electrochemical processes of
various embodiments set forth herein may be used in a generic way
to form various distinct components simultaneously on a single
substrate where the components may be formed in their final
positions and with many if not all of their desired
interconnections. In some embodiments single or multiple identical
or distinct components may be formed directly onto integrated
control circuits or other substrates that include premounted
components. In some embodiments, it may be possible to form entire
systems from a plurality of monolithically formed and positioned
components.
[0215] In still further embodiments, the devices or groups of
devices may be formed along with structures that may be used for
packaging the components. Such packaging structures are set forth
in U.S. Patent Application No. 60/379,182 which is described in the
table of patent application set forth hereafter. This incorporated
application teaches several techniques for forming structures and
hermetically sealable packages. Structures may be formed with holes
that allow removal of a sacrificial material. After removal of the
sacrificial material, the holes may be filled in a variety of ways.
For example, adjacent to or in proximity to the holes a meltable
material may be located which may be made to flow and seal the
holes and then resolidify. In other embodiments the holes may be
plugged by locating a plugging material in proximity to but spaced
from the openings and after removal of sacrificial material then
causing the plugging material to bridge the gaps associated with
the holes and seal them either via a solder like material or other
adhesive type material. In still other embodiments, it may be
possible to perform a deposition to fill the holes, particularly if
such a deposition is essentially a straight line deposition process
and if underneath the holes a structural element is located that
can act as a deposition stop and build up point from which the
deposit can build up to plug the holes.
[0216] Though the application has focused the bulk of its teachings
on coaxial transmission lines and coaxial filters, it should be
understood that these structures may be used as fundamental
building blocks of other structures. As such, RF and microwave
components of various embodiments may include one or more of a
microminiature coaxial component, a transmission line, a low pass
filter, a high pass filter, a band pass filter, a reflection-based
filter, an absorption-based filter, a leaky wall filter, a delay
line, an impedance matching structure for connecting other
functional components, one of a class of antennas, a directional
coupler, a power combiner (e.g., Wilkinson), a power splitter, a
hybrid combiner, a magic TEE, a frequency multiplexer, or a
frequency demultiplexer. The antennas include pyramidal (i.e.,
smooth wall) and scalar (corrugated wall) feedhorns--components
that can efficiently transfer microwave power from the
microminiature transmission line into free space. EFAB produced
microminiature coax will also enable new components with multiple
functionalities. The combination of power combining (or splitting)
and frequency multiplexing (or demultiplexing) could readily be
combined in a single microminiature-coax structure having multiple
input and output ports.
[0217] Other embodiments of the present invention may involve the
formation and use of waveguides and waveguide components. Some
embodiments may involve the formation of discrete components that
may be combined manually or automatically while may involve the
formation of entire systems such as signal distribution networks
and the like.
[0218] The patent applications in the following table are hereby
incorporated by reference herein as if set forth in full. The gist
of each patent application is included in the table to aid the
reader in finding specific types of teachings. It is not intended
that the incorporation of subject matter be limited to those topics
specifically indicated, but instead the incorporation is to include
all subject matter found in these applications. The teachings in
these incorporated applications can be combined with the teachings
of the instant application in many ways. For example, the various
apparatus configurations disclosed in these referenced applications
may be used in conjunction with the novel features of the instant
invention to provide various alternative apparatus that include the
functionality disclosed herein:
TABLE-US-00007 US Pat App No, Filing Date US App Pub No, Pub Date
Inventor, Title 09/493,496 - Jan. 28, 2000 Cohen, "Method For
Electrochemical Fabrication" PAT 6,790,377 - Sep. 14, 2004
10/677,556 - Oct. 1, 2003 Cohen, "Monolithic Structures Including
Alignment and/or 2004-0134772 - Jul. 15, 2004 Retention Fixtures
for Accepting Components" 10/830,262 - Apr. 21, 2004 Cohen,
"Methods of Reducing Interlayer Discontinuities in 2004-0251142A -
Dec. 16, 2004 Electrochemically Fabricated Three-Dimensional
Structures" PAT 7,198,704 Apr. 3, 2007 10/271,574 -Oct. 15, 2002
Cohen, "Methods of and Apparatus for Making High Aspect
2003-0127336A - Jul. 10, 2003 Ratio Microelectromechanical
Structures" PAT 7,288,178 - Oct. 30, 2007 10/697,597 - Dec. 20,
2002 Lockard, "EFAB Methods and Apparatus Including Spray
2004-0146650A - Jul. 29, 2004 Metal or Powder Coating Processes"
10/677,498 - Oct. 1, 2003 Cohen, "Multi-cell Masks and Methods and
Apparatus for 2004-0134788 - Jul. 15, 2004 Using Such Masks To Form
Three-Dimensional Structures" PAT 7,235,166 - Jun. 26, 2007
10/724,513 - Nov. 26, 2003 Cohen, "Non-Conformable Masks and
Methods and 2004-0147124 - Jul. 29, 2004 Apparatus for Forming
Three-Dimensional Structures" PAT 7,368,044 - May 6, 2008
10/607,931 - Jun. 27, 2003 Brown, "Miniature RF and Microwave
Components and 2004-0140862 - Jul. 22, 2004 Methods for Fabricating
Such Components" PAT 7,239,219 - Jul. 3, 2007 10/841,100 - May 7,
2004 Cohen, "Electrochemical Fabrication Methods Including Use
2005-0032362 - Feb. 10, 2005 of Surface Treatments to Reduce
Overplating and/or PAT 7,109,118 - Sep. 19, 2006 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 Deposition 2004-0000489A - Jan. 1, 2004 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 Structures 2003-0234179 A - Using Sacrificial Metal
Patterns" Dec. 25, 2003 PAT 7,229,542 - Jun. 12, 2007 10/434,103 -
May 7, 2004 Cohen, "Electrochemically Fabricated Hermetically
Sealed 2004-0020782A - Feb. 5, 2004 Microstructures and Methods of
and Apparatus for PAT 7,160,429 - Jan. 9, 2007 Producing Such
Structures" 10/841,006 - May 7, 2004 Thompson, "Electrochemically
Fabricated Structures Having 2005-0067292 - May 31, 2005 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 Electrochemically 2004-0007470A - Jan. 15, 2004
Fabricating Structures Via Interlaced Layers or Via Selective PAT
7,252,861 - Aug. 7, 2007 Etching and Filling of Voids" 10/724,515 -
Nov. 26, 2003 Cohen, "Method for Electrochemically Forming
Structures 2004-0182716 - Sep. 23, 2004 Including Non-Parallel
Mating of Contact Masks and PAT 7,291,254 - Nov. 6, 2007
Substrates" 10/841,347 - May 7, 2004 Cohen, "Multi-step Release
Method for Electrochemically 2005-0072681 - Apr. 7, 2005 Fabricated
Structures" 60/533,947 - Dec. 31, 2003 Kumar, "Probe Arrays and
Method for Making" 10/841,300 - May 7, 2004 Cohen, "Methods for
Electrochemically Fabricating 2005 0032375 - Feb. 10, 2005
Structures Using Adhered Masks, Incorporating Dielectric Sheets,
and/or Seed layers That Are Partially Removed Via Planarization"
60/534,183 - Dec. 31, 2003 Cohen, "Method and Apparatus for
Maintaining Parallelism of Layers and/or Achieving Desired
Thicknesses of Layers During the Electrochemical Fabrication of
Structures" 11/733,195 - Apr. 9, 2007 Kumar, "Methods of Forming
Three-Dimensional Structures 2008-0050524 - Feb. 28, 2008 Having
Reduced Stress and/or Curvature" 11/506,586 - Aug. 8, 2006 Cohen,
"Mesoscale and Microscale Device Fabrication 2007-0039828 - Feb.
22, 2007 Methods Using Split Structures and Alignment Elements" PAT
7,611,616 - Nov. 3, 2009 10/949,744 - Sep. 24, 2004 Lockard,
"Three-Dimensional Structures Having Feature 2005-0126916 - Jun.
16, 2005 Sizes Smaller Than a Minimum Feature Size and Methods PAT
7,498,714 - Mar. 3, 2009 for Fabricating"
[0219] Various other embodiments of the present invention exist.
Some of these embodiments may be based on a combination of the
teachings herein with various teachings incorporated herein by
reference. Some embodiments may not use any blanket deposition
process and/or they may not use a planarization process. Some
embodiments may involve the selective deposition of a plurality of
different materials on a single layer or on different layers. Some
embodiments may use blanket deposition processes that are not
electrodeposition processes. Some embodiments may use selective
deposition processes on some layers that are not conformable
contact masking processes and are not even electrodeposition
processes. Some embodiments may use the non-conformable contact
mask or non-contact masking techniques set forth in the above
referenced US Provisional Application corresponding to
P-US042-B-MG.
[0220] Some embodiments may use nickel as a structural material
while other embodiments may use different materials such as copper,
gold, silver, or any other electrodepositable materials that can be
separated from the a sacrificial material. Some embodiments may use
copper as the structural material with or without a sacrificial
material. Some embodiments may remove a sacrificial material while
other embodiments may not. In some embodiments the sacrificial
material may be removed by a chemical etching operation, an
electrochemical operation, or a melting operation. In some
embodiments the anode may be different from the conformable contact
mask support and the support may be a porous structure or other
perforated structure. Some embodiments may use multiple conformable
contact masks with different patterns so as to deposit different
selective patterns of material on different layers and/or on
different portions of a single layer. In some embodiments, the
depth of deposition will be enhanced by pulling the conformable
contact mask away from the substrate as deposition is occurring in
a manner that allows the seal between the conformable portion of
the CC mask and the substrate to shift from the face of the
conformal material to the inside edges of the conformable
material.
[0221] 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.
* * * * *