U.S. patent application number 11/017325 was filed with the patent office on 2006-06-22 for method for forming ceramic thick film element arrays.
This patent application is currently assigned to PALO ALTO RESEARCH CENTER INCORPORATED. Invention is credited to Stephen D. White, Baomin Xu.
Application Number | 20060130956 11/017325 |
Document ID | / |
Family ID | 35874499 |
Filed Date | 2006-06-22 |
United States Patent
Application |
20060130956 |
Kind Code |
A1 |
White; Stephen D. ; et
al. |
June 22, 2006 |
METHOD FOR FORMING CERAMIC THICK FILM ELEMENT ARRAYS
Abstract
An improved process for producing ceramic thick film array
elements is provided. In this regard, ceramic elements are formed
on a temporary, or printing, substrate by screen printing or other
forming methods. The temporary, or printing, substrate is
advantageously provided with a release layer. This makes it
possible to release the printed and soft-baked ceramic elements
from the temporary substrate and transfer the ceramic elements to
the sintering substrate. The contemplated release technique takes
advantage of the phase transition of a liquid, e.g. water, to
transfer the elements to a sintering substrate. After sintering and
electrode deposition, the ceramic element array is bonded to a
target substrate. Then, the sintering substrate is removed to make
the array available for implementation in a variety of suitable
environments.
Inventors: |
White; Stephen D.; (Santa
Clara, CA) ; Xu; Baomin; (Cupertino, CA) |
Correspondence
Address: |
Joseph D. Dreher;FAY, SHARPE, FAGAN, MINNICH & McKEE, LLP
SEVENTH FLOOR
1100 SUPERIOR AVENUE
CLEVELAND
OH
44114-2579
US
|
Assignee: |
PALO ALTO RESEARCH CENTER
INCORPORATED
|
Family ID: |
35874499 |
Appl. No.: |
11/017325 |
Filed: |
December 20, 2004 |
Current U.S.
Class: |
156/89.11 ;
156/289; 257/E27.006 |
Current CPC
Class: |
H01L 41/313 20130101;
H01L 27/20 20130101; H01L 41/43 20130101 |
Class at
Publication: |
156/089.11 ;
156/289 |
International
Class: |
C03B 29/00 20060101
C03B029/00; B32B 37/00 20060101 B32B037/00 |
Claims
1. A method comprising: forming ceramic elements on a temporary
substrate; transferring the ceramic elements onto a sintering
substrate having a temporary adhesion layer by transitioning the
temporary adhesion layer through phase changes; sintering the
ceramic elements; and, transferring the ceramic elements to a
target substrate.
2. The method as set forth in claim 1 wherein the ceramic elements
are piezoelectric elements.
3. The method as set forth in claim 1 wherein the ceramic elements
are lead zirconate titanate (PZT).
4. The method as set forth in claim 1 wherein the temporary
adhesion layer is water.
5. A method for forming thick film ceramic element arrays, the
method comprising: providing a printing substrate having a release
layer; applying a carrier coating to the release layer; forming
ceramic elements on the carrier coating; providing a sintering
substrate with a temporary adhesion layer; joining the printing
substrate and the sintering substrate such that the ceramic
elements are embedded in the temporary adhesion layer; initiating a
phase change on the temporary adhesion layer; removing the printing
substrate and the release layer such that the ceramic elements
remain in the temporary adhesion layer; removing the temporary
adhesion layer such that the ceramic elements remain on the
sintering substrate; sintering the ceramic elements on the
sintering substrate; depositing electrodes on the ceramic elements;
and, transferring the ceramic elements to a target substrate.
6. The method as set forth in claim 5 further comprising providing
tape between the release layer and the printing substrate.
7. The method as set forth in claim 5 wherein applying the carrier
coating comprises spin coating.
8. The method as set forth in claim 5 wherein the carrier coating
is a vehicle used to form ceramic paste.
9. The method as set forth in claim 5 wherein the forming of
ceramic elements comprises forming piezoelectric elements.
10. The method as set forth in claim 5 wherein the forming of
ceramic elements comprises forming lead zirconate titantate (PZT)
elements.
11. The method as set forth in claim 5 wherein the forming of
ceramic elements comprises screen printing.
12. The method as set forth in claim 5 wherein the forming of
ceramic elements comprises jet printing, extrusion, and other
deposition methods.
13. The method as set forth in claim 5 wherein the thickness of the
ceramic elements after sintering is between about 10 .mu.m to about
100 .mu.m.
14. The method as set forth in claim 5 wherein the thickness of the
ceramic elements after sintering is less than 10 .mu.m or more than
100 .mu.m.
15. The method as set forth in claim 5 wherein the temporary
adhesion layer is water.
16. The method as set forth in claim 5 wherein the phase change
comprises a change from a liquid phase to a solid phase of
water.
17. The method as set forth in claim 5 wherein initiating the phase
change comprises freezing.
18. The method as set forth in claim 5 wherein the removing of the
adhesion layer comprises melting and drying.
19. The method as set forth in claim 5 further comprising
depositing second electrodes on the ceramic elements.
20. A method of forming lead zirconate titanate (PZT) thick film
ceramic element arrays, the method comprising: providing a printing
substrate having a release layer; applying a vehicle layer to the
release layer; forming PZT elements on the vehicle layer; providing
a sintering substrate with a water layer; joining the printing
substrate and the sintering substrate such that the PZT elements
are wetted by the water layer; freezing the water layer; removing
the printing substrate and the release layer such that the PZT
elements remain in the frozen water layer; melting and drying the
water layer such that the PZT elements remain on the sintering
substrate; sintering the PZT elements on the sintering substrate;
depositing electrodes on the PZT elements; and, transferring the
PZT elements to a target substrate.
Description
BACKGROUND
[0001] The present exemplary embodiments relate to a method for
forming ceramic thick film element arrays. It finds particular
application in conjunction with the formation of ceramic elements
such as piezoelectric thick film arrays, such as lead zirconate
titanate (PZT) arrays, and will be described with particular
reference thereto. However, it is to be appreciated that the
present exemplary embodiments are also amenable to other like
applications such as production of other ceramic thick film
arrays.
[0002] By way of background, thick (e.g., 10 to 100 .mu.m thickness
range) ceramic or piezoelectric material, such as PZT films, have
many potential uses in micro-electromechanical (MEMS) devices,
inkjet printers and ultrasonic transducers. However, producing
films in this thickness range on commonly used substrates such as
silicon, metal and plastic has been found to be very difficult.
These substrates cannot withstand the temperatures used to sinter
the ceramic thick films. Generally, it is beyond the ability of
thin film methods such as sol-gel and sputtering to produce
suitable devices. It is likewise beyond the ability of bulk ceramic
processing to do so.
[0003] A number of processes for forming thin film materials or
bulk materials are known. For example, U.S. Pat. No. 6,071,795,
entitled "Separation of Thin Films from Transparent Substrates by
Selective Optical Processing," discloses a method for separating a
thin film of gallium nitride that is grown on a sapphire substrate.
The thin film is bonded to an acceptor substrate, and the sapphire
substrate is laser irradiated with a scanned beam at a wavelength
at which the sapphire is transparent but the gallium nitride is
strongly absorbing. After the laser irradiation, the sample is
heated above the melting point of gallium, and the acceptor
substrate and attached gallium nitride thin film are removed from
the sapphire growth substrate.
[0004] Another method relating to the transfer of bulk and thin
film materials is disclosed in U.S. Pat. No. 6,335,263, entitled
"Method of Forming a Low Temperature Metal Bond for Use in the
Transfer of Bulk and Thin Film Materials". In this document, a
method of forming a low temperature metal bond is disclosed as
including a step of providing a donor substrate, having a thin film
grown thereon. An acceptor substrate is then produced and a
multilayer metal bond interface for positioning between the thin
film and the acceptor substrate is then selected. A bonded layer is
then formed between the thin film and the acceptor substrate using
the multilayer metal bond interface. The donor substrate is then
severed from the thin film to isolate the thin film for subsequent
processing.
[0005] Both of these methods contemplate the use of sapphire. As
those of skill in the art will appreciate, sapphire is expensive
and may, thus, render implementation on a large scale impractical.
Both of these methods also contemplate the use of irradiation, e.g.
laser lift-off, to release elements from a substrate.
[0006] Moreover, conventional ceramic thick films, such as
screen-printed PZT films, need to be sintered at more than
1100.degree. C. Thus, only a few substrates--such as aluminum oxide
or zirconium oxide--can be used. Therefore, even if one were to
attempt to adapt and use the above referenced thin film
applications for thick film applications, there are several
apparent drawbacks. First, such a method of production would
require a large, up-front investment to buy the expensive sapphire
substrates. The expected return (e.g. profit) to be enjoyed by the
resultant ceramic material made from this process would typically
not justify the cost of the sapphire substrates. Secondly,
sintering the ceramic elements at 1250.degree. C. or higher in a
lead rich environment would surely result in some diffusion or
inter-reaction, i.e. undesired bonding, between the ceramic, or
PZT, films and the substrate. This will make the contemplated laser
liftoff more difficult and may increase the process cost.
[0007] Accordingly, an improved and more efficient process is
desired to transfer ceramic elements, such as thick film PZT
elements, from a substrate upon which they are formed (but which
does not comprise a sintering substrate), without using an optical
or radiation technique.
BRIEF DESCRIPTION
[0008] In accordance with one aspect of the present exemplary
embodiments, a method comprises forming ceramic elements on a
temporary substrate, transferring the ceramic elements onto a
sintering substrate having a temporary adhesion layer by
transitioning the temporary adhesion layer through phase changes,
sintering the ceramic elements and transferring the ceramic
elements to a target substrate.
[0009] In accordance with another aspect of the present exemplary
embodiments, the ceramic elements are piezoelectric elements.
[0010] In accordance with another aspect of the present exemplary
embodiments, the ceramic elements are lead zirconate titanate
(PZT).
[0011] In accordance with another aspect of the present exemplary
embodiments, the temporary adhesion layer is water.
[0012] In accordance with another aspect of the present exemplary
embodiments, a method for forming thick film ceramic element arrays
comprises providing a printing substrate having a release layer,
applying a carrier coating to the release layer, forming ceramic
elements on the carrier coating, providing a sintering substrate
with a temporary adhesion layer, joining the printing substrate and
the sintering substrate such that the ceramic elements are embedded
in the adhesion layer, implementing a phase change to promote the
adhesion, removing the printing substrate and the release layer
such that the ceramic elements remain in the adhesion layer,
removing the adhesion layer such that the ceramic elements remain
on the sintering substrate, sintering the ceramic elements on the
sintering substrate, depositing optional electrodes on the ceramic
elements and transferring the ceramic elements to a target
substrate, and finally depositing optional secondary electrodes on
the ceramic elements.
[0013] In accordance with another aspect of the present exemplary
embodiments, the method further comprises providing tape between
the release layer and the printing substrate.
[0014] In accordance with another aspect of the present exemplary
embodiments, applying the carrier coating comprises spin
coating.
[0015] In accordance with another aspect of the present exemplary
embodiments, the carrier coating is a vehicle used to form ceramic
paste.
[0016] In accordance with another aspect of the present exemplary
embodiments, the forming of ceramic elements comprises forming
piezoelectric elements.
[0017] In accordance with another aspect of the present exemplary
embodiments, the forming of ceramic elements comprises forming lead
zirconate titanate (PZT).
[0018] In accordance with another aspect of the present exemplary
embodiments, the temporary adhesion layer is water.
[0019] In accordance with another aspect of the present exemplary
embodiments, the phase change comprises changing from a liquid
phase to a solid phase of water.
[0020] In accordance with another aspect of the present exemplary
embodiments, implementing the phase change comprises freezing.
[0021] In accordance with another aspect of the present exemplary
embodiments, the removing of the adhesion layer comprises melting
and drying.
[0022] In accordance with another aspect of the present exemplary
embodiments, the method further comprises depositing second
electrodes on the ceramic elements.
[0023] In accordance with another aspect of the present exemplary
embodiments, the method comprises providing a printing substrate
having a release layer, applying a vehicle layer to the release
layer, forming PZT elements on the vehicle layer, providing a
sintering substrate having a water layer, joining the printing
substrate and the sintering substrate such that the PZT elements
are wetted by the water layer, freezing the water, removing the
printing substrate and the release layer such that the PZT elements
remain in the frozen water, melting and drying the water, sintering
the PZT elements on the sintering substrate, depositing electrodes
on the PZT elements and transferring the PZT elements to a target
substrate, and finally depositing secondary electrodes on the PZT
elements.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is a flow chart illustrating a method according to
the present exemplary embodiments;
[0025] FIG. 2 is an illustration of a part of a method according to
the present exemplary embodiments;
[0026] FIG. 3 is an illustration of a part of a method according to
the present exemplary embodiments;
[0027] FIG. 4 is an illustration of a part of a method according to
the present exemplary embodiments;
[0028] FIG. 5 is an illustration of a part of a method according to
the present exemplary embodiments;
[0029] FIG. 6 is an illustration of a part of a method according to
the present exemplary embodiments;
[0030] FIG. 7 is an illustration of a part of a method according to
the present exemplary embodiments;
[0031] FIG. 8 is an illustration of a part of a method according to
the present exemplary embodiments;
[0032] FIG. 9 is an illustration of a part of a method according to
the present exemplary embodiments;
[0033] FIG. 10 is an illustration of a part of a method according
to the present exemplary embodiments;
[0034] FIG. 11 is an illustration of a part of a method according
to the present exemplary embodiments;
[0035] FIG. 12 is an illustration of a part of a method according
to the present exemplary embodiments;
[0036] FIG. 13 is an illustration of a part of a method according
to the present exemplary embodiments;
[0037] FIG. 14 is an illustration of a part of a method according
to the present exemplary embodiments; and,
[0038] FIG. 15 is an illustration of a part of a method according
to the present exemplary embodiments.
DETAILED DESCRIPTION
[0039] According to the presently described exemplary embodiments,
an improved process for producing ceramic thick film array elements
is provided. In this regard, ceramic elements are formed or screen
printed on a temporary, or printing, substrate. The temporary, or
printing, substrate is advantageously provided with a release
layer. This makes it possible to release the printed and soft-baked
ceramic elements from the temporary substrate. The contemplated
release technique takes advantage of the phase transition of a
liquid, e.g. water, to transfer the elements to a sintering
substrate. After sintering and optional electrode deposition, the
ceramic element array is bonded or transferred to a target
substrate. One of the bonding methods could be using a thin epoxy
bond which can provide electric contact through the asperity points
on the surface of the ceramic elements or the target substrate.
Then, the sintering substrate is removed to make the array
available for implementation in a variety of suitable environments.
Optional secondary electrodes deposition can be made after removing
the sintering substrate.
[0040] In this way, a process for making, for example,
piezoelectric (PZT) thick film element arrays on virtually any kind
of substrate, is implemented. An advantage of such a technique is
that it does not require any optical or radiation technique.
Moreover, the process is not overburdened with expensive materials
and processes.
[0041] Referring now to FIG. 1, in an illustrative method 10 (that
will be described in greater detail below with reference to FIGS. 2
through 15), a temporary substrate is prepared with a release layer
for printing (at 12) and a carrier coating is applied or spin
coated onto the release layer surface and then soft baked (at 14).
Next, ceramic elements such as PZT elements are screen printed or
otherwise formed onto the prepared substrate (at 16). A sintering
substrate (i.e., ceramic alumina) is then prepared with an adhesion
layer, e.g., wetted with enough water to totally wet the PZT
elements and the surrounding dried vehicle when joined (at 18). The
printed substrate is then joined or stacked with the sintering
substrate by placing its printed side (appropriately registered
with the sintering substrate) against the water allowing it to
totally wet the soft-baked PZT and vehicle (at 20). Any excess
water is removed and the substrate stack is placed in a freezer
(-43.degree. C.) for approximately twenty (20) minutes to initiate
a phase change of the water from liquid to solid (at 22). The
frozen assembly is removed from the freezer. The temporary
substrate along with the release layer are then removed (at 24),
leaving the ceramic elements and vehicle layer frozen to the
sintering substrate/ice. This remaining assembly is placed into a
drying oven where the water is allowed to evaporate (i.e.,
105.degree. C. for 10 minutes) (at 26). The dried assembly is
sintered (at 28) and appropriate electrodes are deposited (at 30).
Finally, the PZT elements are transferred to the appropriate target
substrate using an epoxy bonding method or any other suitable
methods (at 32). Other electrodes may be optionally deposited (at
34).
[0042] Referring now to FIG. 2, a temporary, or printing, substrate
100 has disposed or formed thereon a release layer 102 upon which
ceramic elements (such as PZT elements) may be printed. The
temporary substrate 100 may take a variety of forms; however, in
this exemplary case, a glass substrate is used. The release layer
102 may likewise take a variety of suitable forms. In addition, the
release layer 102 may be applied to the temporary substrate 100 in
a variety of manners. In one exemplary form, the release layer 102
includes a high tack release side and a low tack release side and
is adhered to the temporary substrate 100 using a tape 104. In one
form, the tape is of an acrylic type and has a high tack side and a
low tack side. Although a variety of configurations will suffice,
in one example embodiment, the low tack side of the acrylic tape
104 is applied to the temporary substrate 100 while the high tack
side of the acrylic tape 104 faces the release liner. In this
illustrative configuration, the low tack release side of the
release layer 102 thus faces the high tack side of the acrylic tape
104. Consequently, the high tack release side of the release layer
102 faces away from the tape 104 and the temporary substrate 100 to
provide a surface upon which ceramic elements, such as PZT
elements, may be printed or otherwise formed without premature
release.
[0043] It should be understood by those of skill in the art that
the release layer 102 and associated tape 104 may be comprised of
double-sided tape that is commercially available. For example, one
such suitable tape bears the 3M brand and is sold as "3M
Repositionable Tape 9415PC." Of course, even using commercially
available tape, it may be necessary to adapt the product to fit the
objectives of the presently described embodiments. For example, the
liner that is typically provided with the tape may serve as the
release layer 102, but it may need to be reoriented as described
above to provide the appropriate level of adhesion on the printing
surface.
[0044] It should also be understood that it can be difficult to
directly print PZT elements onto release paper. The problem is that
there is typically not enough adhesion force between a first layer
of soft-baked PZT slurry and the release paper when a successive
layer of PZT slurry is printed. However, by providing an extra
carrier coating on the release layer, high-quality PZT elements can
be printed. Such quality is consistent with the quality achieved by
printing directly on sapphire. The PZT elements are then screen
printed as one or a sequence of several layers onto the prepared
substrate in registration with one another in the case of several
layers (each one individually soft-baked).
[0045] In this regard, referring now to FIG. 3, a carrier coating
106 has been spin coated, or spun, onto the release layer 102. The
coating may vary in thickness depending on the exact materials
used, the process conditions, . . . , etc.; however, in one form,
the coating is sufficiently thick to provide structural integrity
during the process. In addition, spinning the material over the
entire surface will allow for improved results, as compared to
merely coating the areas where the printing will take place. The
coating 106 is then soft-baked (e.g., baked at approximately
60.degree. C.-80.degree. C.).
[0046] The carrier coating 106 may take a variety of forms.
However, in one form, the carrier coating 106 as embodied could be
an organic vehicle used in the manufacture of ceramic pastes, such
as ethyl cellulose. Ethyl cellulose is commonly used as a vehicle
in the manufacture of the exemplary PZT paste that is ultimately
printed thereon.
[0047] Referring to FIG. 4, ceramic elements such as PZT elements
108 have been screen printed as one or a succession of several
layers of ceramic paste onto the soft-baked carrier coating 106. It
will be understood that the ceramic paste that is used in this
exemplary embodiment is a PZT paste comprised of PZT powder, a
vehicle such as ethyl cellulose and a solvent such as terpinol. Any
suitable screen printing technique that allows for the formation of
multiple layers of the elements without undue pressure may be
implemented. In at least one form, the technique is conducive to
the registration of one layer to the next layer. It should be
appreciated that the screen-printing pattern and technique will
vary depending on the ultimate application. These elements 108 are
then soft baked (one layer at a time if multi-layered) at
approximately 60.degree. C.-80.degree. C. to transform them from a
paste-like material to a solid, albeit relatively weak, material.
In this regard, the soft-baking process typically removes the
solvent from the slurry of paste to render it solid, but it does
not harden the compound. In addition to screen printing, other
forming methods can also be used to form the ceramic elements,
which include, but are not limited to, jet printing, extrusion, and
tape casting.
[0048] Referring now to FIG. 5, a sintering substrate 150 (e.g., a
substrate formed of ceramic alumina or other similar heat resistant
material) is provided with a temporary bonding or adhesive layer.
In one form, the temporary bonding or adhesive layer takes the form
of a water layer 152. This layer 152 includes enough liquid to
totally wet the PZT elements 108 and the surrounding soft-baked
vehicle or carrier coating 106. As will be appreciated, water is a
suitable material for providing the temporary adhesive layer
because it provides adhesive qualities in its solid form but leaves
no residue once removed (e.g. through evaporation). It will be
understood that other materials can be used as an alternative to
water. For example, other sublimable materials may be used. In
addition, any other material that has a phase transition that may
serve to provide a temporary adhesive layer would suffice.
[0049] Referring to FIG. 6, the printed substrate of FIG. 4 has
been placed with its printed side against the layer 152 on the
sintering substrate 150. Any excess liquid is removed. The ceramic
elements are essentially embedded within the temporary adhesion
layer. Then, the substrate stack placed in a freezer (at
approximately -43.degree. C.) for approximately twenty (20)
minutes. Of course, the temperature and time period will vary from
application to application.
[0050] As shown in FIG. 7, the assembly of FIG. 6 has been removed
from the freezer. Of note, the layer 152 has undergone a phase
transition from a liquid phase to a solid phase. The other elements
remain in substantially the same state as before.
[0051] Next, referring to FIG. 8, the temporary substrate 100 and
release layer 102 have been removed, leaving the ceramic elements
such as PZT elements 108 and carrier coating or vehicle layer 106
frozen to the layer 152 of the sintering substrate 150. A
sufficient force is simply applied to release the substrate.
Advantageously, and as noted above, the frozen water (ice) layer
152 works effectively as an adhesion layer to maintain the ceramic
elements as being connected to the sintering substrate 150 so that
the temporary substrate 100 and the release layer 102 can be
removed without destroying the ceramic elements.
[0052] With reference to FIG. 9, this remaining assembly has been
placed into a drying oven where the water has been allowed to
evaporate (at approximately 105.degree. C. for approximately 10
minutes).
[0053] Referring to FIG. 10, where the coating layer 106 has been
burned away and the ceramic elements such as PZT elements have been
sintered at approximately 1100 to 1300.degree. C. for
densification. Depending on the materials used to form the ceramic
elements, the sintering process could compose of one stage or two
stages. For example, for sintering PZT elements, the sintering
process may include two stages. The first stage is to slowly heat
(e.g., at a ramp rate of 0.2-2.degree. C./min) the PZT elements to
400-800.degree. C. to burn out the carrier coating 106 and organic
vehicles in the PZT elements. In this stage, the PZT elements are
placed in an open environment. The second stage is that, after
cooling down, the PZT elements are placed in a controlled or closed
environment, e.g., in a closed crucible, in order to reduce the
lead loss at high temperatures, and the PZT elements will be heated
to 1100-1300.degree. C. for densification at a relatively fast
heating rate (e.g., at a ramp rate of 4-10.degree. C./min).
Regardless of the number of stages in the sintering process, the
elements should remain in a suitable position with careful
handling. If necessary, however, recesses may be formed in the
sintering layer to soft hold the ceramic elements so that the
configuration/registration of the ceramic elements array will
remain intact. Also, the shrinkage in the lateral dimensions will
be allowed so that denser ceramic elements can be obtained, and the
layer structure may be minimized or eliminated.
[0054] As shown in FIG. 11, appropriate electrodes 154 have been
deposited. Any suitable techniques for depositing electrodes could
be used. However, any such technique should maintain the
registration of the elements. In some embodiments, electrode
deposition may not be necessary at this point.
[0055] After sintering and optional electrode deposition, various
bonding methods could be used to bond the ceramic elements to the
final target substrate. The final target substrate may take a
variety of forms depending on the implementation. For example, it
could be of a ceramic material or silicon-based material. If
electrical contact between the electrode on the ceramic elements
and the target substrate (or surface of the target substrate) is
required, one possible bonding method is thin epoxy bonding. Thus
the electric contact can be realized through the asperity points on
the ceramic elements and/or on the surface of the target substrate.
Referring to FIG. 12, an appropriate bonding epoxy 162 has been
applied to a target substrate 160 and then placed in register onto
the existing assembly. Other bonding techniques such as metal
bonding could also be used.
[0056] Then, as shown in FIG. 13, the target substrate 160 has been
bonded to the electrodes 154. This is accomplished with application
of a sufficient force.
[0057] As in FIG. 14, the sintering substrate 150 has been removed.
A slight force could be used to initiate the removal.
[0058] Last, with reference to FIG. 15, the final conductive
electrodes 156 have been applied. In some cases, the surface of the
ceramic elements may need to be cleaned or polished before applying
electrodes. However, as noted above, in some forms, electrodes may
not be deposited at this point.
[0059] The present exemplary embodiments provide many advantages.
For example, a transfer method, without using optics or radiation,
is achieved.
[0060] Second, high quality ceramic films such as PZT thick film
elements can be obtained because the sintering temperatures are not
limited by the substrate. Also, a clean and low temperature process
is implemented and is desired for the final-use substrate. It is
also compatible with silicon microelectronics.
[0061] In addition, the cost of the process can be extremely low
and very large area ceramic arrays can be made because it avoids
the use of sapphire or other expensive substrates.
[0062] While particular embodiments have been described,
alternatives, modifications, variations, improvements, and
substantial equivalents that are or may be presently unforeseen may
arise to applicants or others skilled in the art. Accordingly, the
appended claims as filed and as they may be amended are intended to
embrace all such alternatives, modifications, variations,
improvements, and substantial equivalents.
* * * * *