U.S. patent application number 09/874165 was filed with the patent office on 2002-02-14 for method for manufacturing microfabrication apparatus.
Invention is credited to Hara, Masaki.
Application Number | 20020019064 09/874165 |
Document ID | / |
Family ID | 18670578 |
Filed Date | 2002-02-14 |
United States Patent
Application |
20020019064 |
Kind Code |
A1 |
Hara, Masaki |
February 14, 2002 |
Method for manufacturing microfabrication apparatus
Abstract
To offer a microstructure fabrication apparatus capable of
realizing MEMS and a Rugate Filter excellent in performance
characteristics by patterning a thick functional material film in
high aspect ratio with a simple and practical manufacturing method.
A Si layer is employed for a mask pattern. The advantages of the Si
layer are withstood a process conducted at high temperature for
forming a PZT layer, which is the functional material layer,
patterned in high aspect ratio, and achieves excellent process
consistency for the whole manufacturing processes of the
microfabrication. A trench or a gap is formed with the mask pattern
deeper than the desired PZT layer. The PZT layer, or functional
material layer (films) is formed on the whole surface including the
bottom of the concave part of the mask pattern. The PZT layer
deposited on the mask pattern is removed with the mask pattern
itself, and selectively remains the pattern of the PZT layer,
thereby obtaining a pattern of the desired functional material
layer.
Inventors: |
Hara, Masaki; (Kanagawa,
JP) |
Correspondence
Address: |
William S. Frommer, Esq.
FROMMER LAWRENCE & HAUG LLP
745 Fifth Avenue
New York
NY
10151
US
|
Family ID: |
18670578 |
Appl. No.: |
09/874165 |
Filed: |
June 4, 2001 |
Current U.S.
Class: |
438/3 |
Current CPC
Class: |
B81C 2201/034 20130101;
B81C 1/0019 20130101 |
Class at
Publication: |
438/3 |
International
Class: |
H01L 021/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 5, 2000 |
JP |
2000-167421 |
Claims
What is claimed is:
1. A method for manufacturing a microfabrication apparatus
comprising steps of: forming a mask pattern by providing a trench
or a gap deeper than a desired functional material layer within a
semiconductor layer; depositing the functional material layer in a
manner to be thinner than the semiconductor layer; and obtaining a
pattern of the functional material layer by removing the mask
pattern.
2. A method for manufacturing a microfabrication apparatus
according to claim 1 comprising a step of: bonding the silicon
substrate on another substrate with an anodix oxidation method;
wherein the silicon substrate is employed as the semiconductor
layer.
3. A method for manufacturing a microfabrication apparatus
according to claim 1, wherein a silicon portion of a SOI substrate
is employed as the semiconductor layer.
4. A method for manufacturing a microfabrication apparatus
according to claim 1, wherein the functional material layer is
deposited with a gas deposition method.
5. A method for manufacturing a microfabrication apparatus
according to claim 1, wherein the mask pattern is formed by a dry
etching method using SF.sub.6 gas and C.sub.4F.sub.8 gas.
6. A method for manufacturing a microfabrication apparatus
according to claim 1, wherein the mask pattern is selectively
removed with XeF.sub.2 or BrF.sub.3.
7. A method for manufacturing a microfabrication apparatus
comprising steps of: forming a mask pattern by coating a surface of
a photoresist layer with a cap film after a trench or a gap deeper
than a desired functional material layer is provided within the
photoresist layer; depositing the functional material layer in a
manner to be thinner than the photoresist layer at least in the
trench or the gap of the mask pattern; and obtaining a pattern made
of the functional material layer by removing the mask pattern.
8. A method for manufacturing a microfabrication apparatus
according to claim 7, wherein the functional material layer is
deposited with a gas deposition method.
9. A method for manufacturing a microfabrication apparatus
comprising steps of: forming a mask pattern by providing a trench
or a gap deeper than a desired functional material layer within an
organic compound film; depositing the functional material layer in
a manner to be thinner than the organic compound film at least in
the trench or the gap of the mask pattern; and obtaining a pattern
of the functional material layer by removing the mask pattern.
10. A method for manufacturing a microfabrication apparatus
according to claim 9, wherein the trench or the gap is provided
within the organic compound film with a laser abrasion method.
11. A method for manufacturing a microfabrication apparatus
according to claim 9 comprises a step of laminating the organic
compound film on another substrate.
12. A method for manufacturing a microfabrication apparatus
according to claim 11, wherein after the trench or the gap is
provided within the organic compound film, the organic compound
film is laminated on another substrate.
13. A method for manufacturing a microfabrication apparatus
according to claim 9, wherein the functional material layer is
deposited with the gas deposition method.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a method for manufacturing
a microfabrication apparatus, which is specifically preferable for
manufacturing Micro Electro Mechanic Systems (hereinafter, it is
referred to as MEMS) or a Rugate Filter, these apparatuses are
required to process a thin functional material film ranging from
several .mu.m to 100 .mu.m or more as a pattern with high aspect
ratio ranging from 3 to 10 or more.
[0003] 2. Description of the Related Art
[0004] In MEMS, a microstructure is formed by processing a
functional material film such as piezoelectric materials or
magnetic materials. For achieving a desired sensing function or
actuation function in practical use, the microstructure is required
to have at least several .mu.m thick or more, desirably, 100 .mu.m
thick or more, and is patterned in a manner of obtaining high
aspect ratio.
[0005] Among them, the piezoelectric material can be both sensor
and actuator functions, so that there are the following advantages:
a structure can be simplified in case of using a single function in
either one of the above two functions, and the piezoelectric
material can be applied to use for the both functions. Therefore,
the piezoelectric material is especially expected to use as a
component material of a main operation portion of MEMS. Similarly,
in a microfabrication apparatus such as the rugate filter using
optical functional materials, for instance, a technique where a
thick functional material is processed as a pattern with high
aspect ratio, is earnestly required besides MEMS.
[0006] In case of employing the piezoelectric material for a
microactuator such as micropump, a small-sized ultra sonic motor,
and a micro cantilever, or for a micro ultra sonic source,
practical performance distance or output is required. Hence, take
PZT, which is a solid solution of lead titanate and lead zirconate
(Pb (Ti, Zr)O.sub.3, hereinafter it is referred to as PZT) for
instance, a thick layer of at least about several .mu.m is needed,
further desirably, a thick layer ranging from several 10 .mu.m to
100 .mu.m or more is useful.
[0007] Conventionally, the structure of the functional material
film made of the above piezoelectric material is manufactured by a
mechanical processing performed in bulk materials or a screen
printing method. For this reason, the mechanical processing and the
screen printing method are techniques capable of forming a pattern
in a thick film. As other methods, for example, a technique where
thin films are laminated many times with sputtering or a CVD
(Chemical Vapor Deposition) method, is suggested.
[0008] However, in the mechanical processing, the functional
material film is hard to be patterned accurately because failure of
members occurs during processing or handling, or characteristics
vary when adhering.
[0009] In case of the screen printing method, sintering temperature
rises at 500 to 800.degree. C. or more, so that the substrate and
other structure members tend to be damaged, and additionally, the
film is hard to be formed in high density. With the above reasons,
there is a tendency where optimum quality as a functional material
layer is failed to obtain.
[0010] Further, in the technique where a thick film is formed with
sputtering or the CVD method, a process of forming film at
comparatively low temperature can be generally conducted.
Meanwhile, deposition of the thick film of several 10 .mu.m or more
considerably takes time, so that the above technique is not
suitable for manufacturing process in practical use. Additionally,
there is a tendency that accurate etching process is difficult to
be performed in the functional material film formed by depositing
many times for a long time.
[0011] A thick film made of the functional material may be formed
with the sputtering or the CVD method, then is patterned with a
lift-off method in stead of etching. Here, in general, the lift-off
method is a method such that photoresist is used as a pattern, then
the pattern is separated in order to gain a desired pattern.
[0012] However, with the lift-off method, only a functional
material film formed at low temperature can be formed. For this
reason, in case of using photoresist as a pattern, deformation or
burning occurs in photoresist when heating the substrate at about
150.degree. C. or more. This fails to perform the lift-off method,
hence, a method for forming the functional material film is
strictly limited due to processing temperature.
[0013] According to a LIGA (Lithographie Galvanoformung Abfprumng)
process employing a X-ray lithography, resist can be realized to
pattern in several 100 .mu.m. However, this method is not
industrially practical in the following points: a X-ray lithography
apparatus is unusual and expensive; special structure using a
material having sufficient shielding characteristics (e.g. Au
(gold)) for a X-ray having high permeability is employed, and an
expensive complicated photomask is needed for manufacturing.
[0014] As other lift-off methods, it is suggested that a SiNx film
or SiO.sub.2 film is employed. In this case, forming layer can be
performed at high temperature, so that limitation on the processing
temperature eases. On the other hand, the SiNx film or the
SiO.sub.2 film is extremely difficult to be patterned in the aspect
ratio 3 or more.
[0015] As described above, each of the conventional techniques has
the problems such that the thick film made of the functional
material having at least several lm or more is difficult or
impossible to be patterned in the high aspect ratio 3 or more. As a
result, various microfabrication apparatuses excellent in
performance characteristics can not be realized.
[0016] The invention has been achieved in consideration of the
above problems and its object is to provide a method for
manufacturing a simple and practical microfabrication apparatus
achieving MEMS and the rugate filter excellent in performance
characteristics by patterning a thick film made of a functional
material film.
SUMMARY OF THE INVENTION
[0017] A method for manufacturing a microfabrication apparatus
comprises steps of forming a mask pattern by providing a trench or
a gap deeper than a desired functional material layer within a
semiconductor layer, depositing the functional material layer in a
manner to be thinner than the semiconductor layer, and obtaining a
pattern of the functional material layer by removing the mask
pattern.
[0018] A method for manufacturing a microfabrication apparatus
comprises steps of forming a mask pattern by coating a surface of a
photoresist layer with a cap film after a trench or a gap deeper
than a desired functional material layer is provided within the
photoresist layer, depositing the functional material layer in a
manner to be thinner than the photoresist layer at least in the
trench or the gap of the mask pattern, and obtaining a pattern made
of the functional material layer by removing the mask pattern.
[0019] A method for manufacturing a microfabrication apparatus
comprises steps of forming a mask pattern by providing a trench or
a gap deeper than a desired functional material layer within an
organic compound film, depositing the functional material layer in
a manner to be thinner than the organic compound film at least in
the trench or the gap of the mask pattern, and obtaining a pattern
of the functional material layer by removing the mask pattern.
[0020] According to the method for manufacturing the
microfabrication apparatus of the present invention, a
semiconductor layer is employed as a mask pattern in order to form
a trench or a gap deeper than a desired functional material layer,
and the functional material layer (film) is formed on the whole
surface including a bottom of a concave part of the trench or the
gap. The advantages of the semiconductor layer are withstood a
process for forming the functional material layer conducted at high
temperature, patterned in high aspect ratio, and achieves excellent
process consistency for the whole manufacturing processes of the
microfabrication apparatus. The functional material layer deposited
on the mask pattern is removed with the mask pattern itself. Then,
the functional material layer deposited on the bottom of the
concave part of the mask pattern only remains selectively in order
to obtain a desired pattern of the functional material layer. In
this time, the trench or the gap deeper than the functional
material layer is provided in the mask pattern, so that the
functional material layer is disposed on the mask pattern and in
the bottom of the concave part of the mask pattern in a manner to
be separated between a pattern edge of the functional material
layer disposed on the concave part of the mask pattern and a
pattern edge of the functional material layer disposed on the mask
pattern. Accordingly, the mask pattern is removed (lift-off)
performed while both sides of the pattern edges of the functional
material layer disposed on the concave part of the mask pattern
keeps intact.
[0021] In the method for manufacturing another microfabrication
apparatus according to the present invention, instead of using the
semiconductor layer as a mask pattern, a photoresist layer further
excellent in process consistency is patterned and coated its
surface with a film cap, and employed.
[0022] In the method for manufacturing another microfabrication
apparatus according to the present invention, instead of using the
semiconductor as a mask pattern, an organic compound film is
employed. The organic compound film is adapted to a larger pattern
and can be patterned or separated more simply.
[0023] A silicon substrate, which can be processed simply is
employed as a semiconductor layer, and the silicon substrate may be
bonded on another substrate such as a grass substrate with an
anodic oxidation method, which is a simple process. A silicon
portion of a SOI (Silicon On Insulator) substrate, which can be
obtained with a simple process may be employed as a semiconductor
layer.
[0024] Other and further objects, features and advantage of the
invention will appear more fully from the following
description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] These and other objects and features of the present
invention will become clear from the following description of the
preferred embodiments given with reference to the accompanying
drawings, in which:
[0026] FIGS. 1A to 1F are views specifically showing a step of
patterning a PZT layer, which is a functional material film with Si
as a mask pattern in a manufacturing method relative to a first
embodiment of the present invention;
[0027] FIG. 2 is a cross sectional view showing a structure of a
micromirror, which is an example of the microfabrication apparatus
produced by a manufacturing method relative to an embodiment of the
present invention;
[0028] FIG. 3 is a cross sectional view showing a structure of a
microactuator, which is an example of the microfabrication
apparatus produced by a manufacturing method relative to an
embodiment of the present invention;
[0029] FIGS. 4A to 4E are views specifically showing a step of
patterning the PZT layer, which is the functional material layer
with resist and a cap film as a pattern in a manufacturing method
relative to a second embodiment of the present invention; and
[0030] FIGS. 5A to 5E are views specifically showing a step of
patterning the PZT layer, which is the functional material layer
with a PET film as a pattern in a manufacturing method relative to
a third embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0031] Embodiments of the present invention will be described in
detail hereinbelow by referring to the drawings.
[0032] [First Embodiment]
[0033] FIGS. 1A to 1E are views showing a manufacturing method
relative to the first embodiment of the present invention. First,
as shown in FIG. 1A, a 4-inch Si (silicon) substrate of about 200
.mu.m thick is bonded on another substrate such as a refractory
grass substrate 1a whose outer dimension is 4 inch long and 200
.mu.m thick with an anodic oxidation method. This Si substrate is a
Si layer 2. The Si layer 2 may be formed by depositing a Si film
having a desired thickness on the grass substrate 1a.
[0034] Next, a photoresist is applied on a surface of the Si layer
2 to form a resist pattern 3 as shown in FIG. 1B with a
photolithography method and the like. While using the resist
pattern 3 as a mask, the Si layer 2 is patterned with a dry etching
method called as a Deep-Si (silicon) RIE (Reactive Ion Etching)
method, which is a kind of Bosch process and further, the resist
pattern 3 is separated so as to form a mask pattern 4 as shown in
FIG. 1C. The mask pattern 4 is employed for patterning the Si layer
2 with the lift-off method. The mask pattern 4 may be a rectangular
shape, and measure by for example, 200 .mu.m long, 10 .mu.m wide,
200 .mu.m deep. The Bosch process is a technique such that SF.sub.6
gas and C.sub.4F.sub.8 gas are alternately supplied to generate
high-density plasma for performing the dry etching.
[0035] The whole substrate on which the Si mask pattern 4 is formed
is exposed to a rare HF (hydrogen fluoride) solution, then cleans
its surface. After this, as shown in FIG. 1D, PZT layers 6a and 6b
of 150 .mu.m in thickness are deposited on the whole surface of the
substrate including the portion on the mask pattern 4 by
insufflating a PZT (lead zirconate titanate) particle flow 5 at
high speed with a gas deposition method (a jet printing method).
However, in this time, the PZT layers 6a and 6b are not always
necessary to be formed on the whole surface of the substrate. The
PZT layer 6a may be selectively formed in the vicinity of the
desired mask pattern 4. A process condition inside a deposition
chamber may be determined in the following conditions: pressure is
133.3 Pa (1 Torr), the distance from a nozzle to the substrate is 5
mm, differential pressure for insufflating from the nozzle is 66.7
Pa (0.5 Torr), and substrate temperature is 100.degree. C. Particle
diameter of raw powder of the PZT layers 6a and 6b is desirably,
for instance, 0.7 .mu.m or lower for ensuring film quality such as
dense and so on.
[0036] Following this, the substrate is maintained inside an
unillustrated vacuum chamber, then, the Si mask pattern 4 and the
PZT layer 6b, which has been deposited thereon are completely
removed by introducing XeF.sub.2 (xenon fluoride) via sublimation,
thereby achieving a pattern made of the PZT layer 6a as shown in
FIG. 1E. In place of XeF.sub.2, the Si mask pattern 4 can be also
removed with BrF.sub.3 (bromine trifluoride). The pressure inside
the vacuum chamber in this time may be determined as about 66.7 Pa.
When the PZT layers 6a and 6b are formed, the surface of the
substrate is planarized by lapping (abrading) if needed, then an
upper electrode and so on (an illustration is omitted in FIGS. 1A
to 1F) can be formed thereon. The electrodes are formed on and
beneath the PZT layer 6a (an illustration is omitted in FIGS. 1A to
1F), thereby completing a functional material layer shown in FIG.
2. The functional material layer is a main structure for operating
the microfabrication apparatus.
[0037] As described above, in the method for manufacturing the
microstructure fabrication apparatus relative to the embodiment,
the pattern of the PZT layer (the functional material layer) 6a
having the following advantages can be obtained: a layer is as
thick as 200 .mu.m; the aspect ratio is extremely as high as 30 or
more, and edge repeatability is excellent. Additionally, the PZT
layer 6a can be deposited in a uniform thickness in a predetermined
position for a short time because of using the gas deposition
method. The Si layer 2 is slightly thicker than the PZT layer 6a in
order to form a little space between the Si mask pattern 4 and the
pattern of the PZT layer 6a. This ensures removing the Si layer 2
since the Si layer 2 is selectively subjected to etching from the
above fine space with XeF.sub.2 or BrF.sub.3.
[0038] By employing the PZT layer 6a patterned with the above
manufacturing method as a piezo element, for example, a micromirror
shown in FIG. 2 and a microactuator (micro cantilever) in FIG. 3
and so on can be manufactured.
[0039] In the micromirror shown in FIG. 2, a mirror face 7 is
operated in an up-down direction in the drawing by controlling
voltage applied to a PZT layer 60. The microactuator shown in FIG.
3 is determined in a manner to operate the cantilever in an up-down
direction in the drawing by controlling voltage respectively
applied to a first PZT layer 61 and a second PZT layer 62.
[0040] In either case of the microfabrication apparatuses, the PZT
film of several 100 .mu.m or more is formed, then processed as the
pattern having high aspect ratio with excellent repeatability,
thereby obtaining the PZT layers 60, 61, and 62. In addition,
because of using the Si layer 2 as the mask pattern 4 for
patterning, the microfabrication apparatus using a material film,
which is necessary to be formed at high temperature can be
manufactured. As a result, the microfabrication apparatus including
sufficient practical functions can be realized.
[0041] In case of the micromirror shown in FIG. 2, steps of forming
a sacrifice layer (an illustration is omitted) for finally forming
a void portion 21, and a SiNx (silicon nitride) layer 22 and Au
(gold) electrodes 23a and 23b are further necessary as well as the
step of forming and patterning the PZT layer 60. In case of the
microactuator shown in FIG. 3, the following steps are further
necessary in order to achieve operation in both up and down
directions in the drawing as the cantilever: a step of forming a
lower Pt (platinum) electrode 31, a middle Pt electrode 32, and an
upper Pt electrode 33, a step of forming the first PZT layer 61 and
the second PZT layer 62 with the middle Pt electrode 32 in-between,
and a step of protruding the structure (the cantilever) using the
PZT layers 61 and 62 after partly removing the substrate 1.
[0042] [Second Embodiment]
[0043] FIGS. 4A to 4E are views showing an example of a case where
a silicon cap film is coated on the surface of the thick
photoresist pattern instead of Si layers and used as a pattern made
of the Si mask pattern. Here, the explanation will be mainly
focused on differences from the first embodiment, the same
processes and effects will be simplified.
[0044] A UV-LIGA method is an ideal technique to perform patterning
on the thick resist with a collimation technique excellent in
straight-line characteristics of UV light. With the UV-LIGA method,
patterning on a desired thick resist can be performed. That is, as
shown in FIG. 4A, for example, a positive UV resist of 150 .mu.m is
applied on the Si substrate 1b of 4 inch long and 400 .mu.m thick,
then photolithography is performed with a mask aligner having
collimation characteristics excellent in straight-line
characteristics, (this is the so-called UV-LIGA method), thereby a
resist pattern 30 whose pattern gap (space) is about 10 .mu.m in
width, 150 .mu.m in depth, and 200 .mu.m in length, is formed.
[0045] With a plasma CVD method using low temperature at about
100.degree. C., for instance, as shown in FIG. 4B, a thin SiO.sub.2
film of about 15 nm is deposited on the almost whole surface of the
substrate including the photoresist pattern 30 functioning as a cap
film 40. The resist pattern 30 coated with the cap film 40 can be
used in a similar manner to the mask pattern 4 in the first
embodiment.
[0046] Next, as shown in FIG. 4C, a PZT particle flow 50 is
insufflated at high speed so as to deposit PZT layers 6c and 6d of
80 .mu.m, for example with the gas deposition method.
[0047] Although an illustration is omitted, after the whole
substrate is immersed in about a five-percent rare HF solution for
a short time to selectively remove the SiO.sub.2 film, as shown in
FIG. 4D, the whole wafer is immersed in a solvent for dissolving
the resist in order to dissolve or separate the photoresist
pattern, and the PZT layer 6d provided thereon is also removed.
This can obtain the pattern made of the PZT layer 6c measuring by
10 .mu.m in width, 80 .mu.m in thickness, and 200 .mu.m in length
as shown in FIG. 4E, for instance, on the Si substrate.
[0048] Generally, there is likely to fail to achieve patterning
excellent in the edge repeatability with the gas deposition method
because the resist pattern 30 is deformed or partly defected when
it is exposed to the high-speed gas flow, which gives shock to the
resist pattern 30. However, as described above, the resist pattern
30 is protected by the cap film 40 made of the thin SiO.sub.2 film,
so that no deformation or defection of the resist pattern 30 occurs
even if the high-speed gas flow is insufflated, thereby patterning
excellent in the edge repeatability can be performed. As the
SiO.sub.2 film 41 remaining between the Si substrate 1b and the
pattern of the PZT layer 6c after patterning the PZT layer, it
practically does not affect on function or quality of the
microfabrication apparatus since the layer is thin for instance, 15
nm and the manufactured piezoelectric element is driven by applying
voltage.
[0049] Dissolution or separation of the photoresist pattern 30 can
be surely performed with a solvent generally in use, so that the
whole process can be further simplified.
[0050] [Third Embodiment]
[0051] FIGS. 5A to 5E are views showing a preferable example for
processing a pattern much larger than the above. First, as shown in
FIG. 5A, a photoresist 51 is applied onto the Si substrate 1c whose
outer dimension is 4 inch long and 400 .mu.m thick with an
unillustrated spin coater and so on, then, with employing the
photoresist film in a pre-dry state as an adhesive material, a PET
(polyethylene terephthalate) film 52 of about 300 .mu.m is
laminated, baked and fixed in order not to separate during the
following processes hereinafter.
[0052] A metal mask 53 excellent in coverage characteristics for a
laser as same as SUS (Stainless Steel) materials, is covered
thereon as shown in FIG. 5B, and a XeCl (xenon fluoride) excimer
laser 54 and so on are irradiated to perform abrasion on the PET
film 52 in order to form a pattern 55 whose gap measures by 50
.mu.m wide, 300 .mu.m thick and 200 .mu.m long as shown in FIG. 5C.
The pattern 55 of the PET film processed as described above is
substantially used as a pattern similar to the mask pattern 4 made
of the Si layer 2 in the first embodiment.
[0053] Following this, the whole body including the Si substrate is
disposed inside the unillustrated vacuum chamber, and subjected to
plasma ashing in order to completely remove residues of the abraded
PET film or adhesive materials and so on remaining in an open
portion of the patterned PET film (the both illustrations are
omitted). While the Si substrate is kept inside the vacuum chamber,
a PZT particle flow 56 is insufflated on the whole substrate with
the gas deposition method so as to deposit PZT layers 6e and 6f of
150 .mu.m, for instance.
[0054] Then, as shown in FIG. 5D, the photoresist 51 used as the
adhesive material including the Si substrate is immersed in an
organic solvent to fuse, thereby removing or separating the pattern
55 of the PET film from the Si substrate. This also removes the PZT
layer 6f formed on the pattern 55, which can obtain the pattern of
the PZT layer 6e of 50 .mu.m in width, 150 .mu.m in height, and 200
.mu.m in length, for instance.
[0055] As described above, the processes employing the PET film as
the mask pattern of the lift-off are preferable for the case where
a pattern, which is larger than a pattern using the Si layer or the
photoresist as a mask pattern, is obtained. In addition, the
pattern having the high aspect ratio can be further ensured to form
with excellent repeatability since the PET film is separated in
one-sheet state without cutting.
[0056] The present invention is not limited to the above
embodiments. The size, material, process condition and so on can be
modified without departing from the spirit of the invention. For
instance, in the first embodiment, the Si portion of the SOI
substrate may be employed as a substrate. The etching method of Si
is not limited to the Boch process and can employ a dry etching
process excellent in direction preference characteristics.
[0057] In the second embodiment, Si may be patterned by wet etching
with a HF--HNO.sub.3 solution instead of XeF.sub.2 gas. The
SiO.sub.2 film employed as the cap film may be formed by, for
instance, an evaporation method besides the CVD method.
[0058] Although in the second embodiment, patterning was performed
after laminating the PET film on the Si substrate, a pre-patterned
PET film may be laminated, which results in simplifying the
process, thereby reducing the manufacturing cost. Instead of the
PET film, for instance, an organic compound film such as a
polyimide film can be employed. The PET film may be removed by
entirely dissolving with the organic solvent instead of separating
in the one-sheet state. As an adhesive material for sealing the PET
film on the substrate, for instance, various adhesive materials
capable of being completely removed with solvents may be employed
in stead of the resist.
[0059] Although the functional material layer was formed and
employed for the micromirror and the microactuator in the above
embodiment, the method for manufacturing the microfabrication
apparatus relative to the present invention can be applied to
functional material layers using piezoelectric materials employed
for MEMS such as a micropump, a small-sized ultrasonic motor, a
micro ultra sonic generation source. The method is also applied to
a method for fabricating an optical microstructure apparatus such
as a rugate filter besides MEMS.
[0060] As a functional material layer, instead of PZT, for example,
soft magnetic materials such as NiZn ferrite with Spinel structure
or various functional ceramics materials such as photocatalysts,
e.g., TiO.sub.2 having an anatase structure can be employed
indisputably.
[0061] As described above, according to the method for
manufacturing the microfabrication apparatus of the present
invention, a thick functional material layer is formed as a dense
thin film with high temperature. Then, patterning is performed with
the process employing the lift-off method where the semiconductor
layer, the photoresist, or the organic compound film are employed
as a mask pattern. Therefore, the pattern with the high aspect
ratio and the excellent edge repeatability can be obtained, thereby
achieving a microstructure apparatus including the structure made
of the thick functional material and excellent in performance
characteristics and output characteristics.
[0062] Obviously many modifications and variations of the present
invention are possible in the light of the above teachings. It is
therefore to be understood that within the scope of the appended
claims the invention may be practiced otherwise than as
specifically described.
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