U.S. patent application number 09/791634 was filed with the patent office on 2001-09-20 for micro-structure and manufacturing method and apparatus.
This patent application is currently assigned to Fuji Xerox Co. Ltd.. Invention is credited to Nagata, Masaki, Takahashi, Mutsuya, Yamada, Takayuki.
Application Number | 20010023010 09/791634 |
Document ID | / |
Family ID | 14628324 |
Filed Date | 2001-09-20 |
United States Patent
Application |
20010023010 |
Kind Code |
A1 |
Yamada, Takayuki ; et
al. |
September 20, 2001 |
Micro-structure and manufacturing method and apparatus
Abstract
A substrate on which a plurality of thin films having a
plurality of cross-sections corresponding to the cross-section of a
micro-structure are formed is placed on a substrate holder. The
substrate holder is elevated to bond a thin film formed on the
substrate to the surface of a stage, and by lowering the substrate
holder, the thin film is separated from the substrate and
transferred to the stage side. The transfer process is repeated to
laminate a plurality of thin films on the stage and to form the
micro-structure. Accordingly, there are provided a micro-structure
having high dimensional precision, especially high resolution in
the lamination direction, which can be manufactured from a metal or
an insulator such as ceramics and can be manufactured in the
combined form of structural elements together, and a manufacturing
method and an apparatus thereof.
Inventors: |
Yamada, Takayuki;
(Nakai-machi, JP) ; Takahashi, Mutsuya;
(Nakai-machi, JP) ; Nagata, Masaki; (Nakai-machi,
JP) |
Correspondence
Address: |
OLIFF & BERIDGE, PLC
P.O. Box 19928
Alexandria
VA
22320
US
|
Assignee: |
Fuji Xerox Co. Ltd.
|
Family ID: |
14628324 |
Appl. No.: |
09/791634 |
Filed: |
February 26, 2001 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09791634 |
Feb 26, 2001 |
|
|
|
09064056 |
Apr 22, 1998 |
|
|
|
6245249 |
|
|
|
|
Current U.S.
Class: |
428/141 ; 216/33;
216/36; 216/38; 216/56; 216/62; 216/66; 428/432; 428/450;
428/469 |
Current CPC
Class: |
Y10T 156/13 20150115;
Y10T 156/14 20150115; B33Y 30/00 20141201; Y10T 156/12 20150115;
B81C 2201/0197 20130101; B81C 99/008 20130101; Y10T 428/24355
20150115; B33Y 10/00 20141201; B81B 2201/035 20130101 |
Class at
Publication: |
428/141 ; 216/33;
216/36; 216/38; 216/56; 216/62; 216/66; 428/432; 428/450;
428/469 |
International
Class: |
B44C 001/22; C03C
015/00; B32B 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 1, 1997 |
JP |
9-114071 |
Claims
What is claimed is:
1. A micro-structure comprising a plurality of laminated thin films
having prescribed two-dimensionally patterned forms.
2. The micro-structure as claimed in claim 1, wherein surfaces of
said plurality of thin films are bonded together in direct
contact.
3. The micro-structure as claimed in claim 1, wherein said whole
micro-structure is composed of only the composition of said
plurality of thin films.
4. The micro-structure as claimed in claim 1, wherein said
micro-structure is composed of a plurality of structural elements
which are relatively movable and combined inseparably.
5. A manufacturing method of micro-structures comprising a first
step for forming a plurality of thin films having prescribed
two-dimensionally patterned forms on a substrate, and a second step
for forming the micro-structure by laminating and bonding said
plurality of thin films on a stage.
6. The manufacturing method of micro-structures as claimed in claim
5, wherein said plurality of thin films are formed on said
substrate with interposition of spaces between thin films in said
first step.
7. The manufacturing method of micro-structures as claimed in claim
5, wherein said plurality of thin films are transferred from said
substrate simultaneously, and said plurality of thin films are
laminated simultaneously on different positions on said stage in
said second step.
8. The manufacturing method of micro-structures as claimed in claim
5, wherein a plurality of thin films having the same
two-dimensional pattern are formed on said substrate with
interposition of spaces in said first step, and said plurality of
thin films having the same two-dimensional pattern are separated
simultaneously in said second step.
9. The manufacturing method of micro-structures as claimed in claim
5, wherein a support thin film is formed surrounding thin films
having said two-dimensional pattern with interposition of a space
on said substrate in said first step, said plurality of thin films
and said support thin film are separated simultaneously from said
substrate and said plurality of thin films and said support thin
film are laminated simultaneously on said stage in said second
step, and after the second step, a third step in which a support
formed of said laminated support thin films surrounding said
micro-structure is removed is provided.
10. The manufacturing method of micro-structures as claimed in
claim 5, wherein said first step is a step in which a thin film is
deposited on said substrate by vacuum vapor deposition or spin
coating, and said plurality of thin films are formed by patterning
said thin film into a prescribed two-dimensional pattern.
11. The manufacturing method of micro-structures as claimed in
claim 10, wherein said patterning process is a process in which a
circumference of said two-dimensional pattern or unnecessary
portion other than said two-dimensional pattern is removed by
irradiating it with a focused ion beam or electron beam.
12. The manufacturing method of micro-structures as claimed in
claim 10, wherein said patterning process is the lithography
process including resist pattern forming and etching.
13. The manufacturing method of micro-structures as claimed in
claim 5, wherein said plurality of thin films are bonded by surface
activated bonding in said second step.
14. The manufacturing method of micro-structures as claimed in
claim 5, wherein said second step includes a process for cleaning
the bonded surface of said stage and said plurality of thin films
in a vacuum chamber.
15. The manufacturing method of micro-structures as claimed in
claim 14, wherein said cleaning process is a process in which said
bonded surface is irradiated with a particle beam.
16. The manufacturing method of micro-structures as claimed in
claim 5, wherein a sacrifice layer which can be selectively removed
after forming said micro-structure by laminating said plurality of
thin films is formed previously on the surface of said stage as an
interface between said thin film and said stage.
17. The manufacturing method of micro-structures as claimed in
claim 5, wherein a releasing layer is formed previously on the
surface of said substrate as an interface between said substrate
and said thin film.
18. The manufacturing method of micro-structures as claimed in
claim 17, wherein said releasing layer is formed by vacuum vapor
deposition or coating of fluorine-containing material or by
exposing the surface of said substrate to discharge of a gas
containing fluorine atoms to fluoridize the substrate surface.
19. A manufacturing method of micro-structures comprising; a first
step for forming a plurality of first thin films having a
prescribed two-dimensional pattern on a substrate, and forming a
plurality of second thin films composed of different material from
that of said first thin films and having the same film thickness as
said first thin film around said plurality of first thin films to
form a plurality of composite thin films composed of said first
thin films and said second thin films, a second step for forming a
laminate including a micro-structure by separating said plurality
of composite thin films from said substrate and subsequently by
laminating and bonding said plurality of composite thin films on a
stage, and a third step for removing said first thin films or said
second thin films out of said laminate to obtain said
micro-structure.
20. The manufacturing method of micro-structures as claimed in
claim 19, wherein said plurality of first thin films are formed on
said substrate with interposition of spaces in said first step.
21. The manufacturing method of micro-structures as claimed in
claim 19, wherein a plurality of said composite thin films are
transferred simultaneously from said substrate and said plurality
of composite thin films are laminated simultaneously at different
positions on said stage in said second step.
22. The manufacturing method of micro-structures as claimed in
claim 21, wherein a plurality of composite thin films having the
same two-dimensional pattern are formed on said substrate with
interposition of spaces between said thin films in said first step,
and said plurality of composite thin films having the same
two-dimensional pattern are transferred simultaneously in said
second step.
23. The manufacturing method of micro-structures as claimed in
claim 19, wherein said first step includes a process in which a
thin film is formed on said substrate by vacuum vapor deposition or
spin coating, and said plurality of first thin films are formed by
patterning said thin film into a prescribed two-dimensional
pattern.
24. The manufacturing method of micro-structures as claimed in
claim 23, wherein said patterning process is a process in which the
circumference of said two-dimensional pattern or unnecessary
portion other than said two-dimensional pattern is removed by
application of a focused ion beam or an electron beam thereto.
25. The manufacturing method of micro-structures as claimed in
claim 23, wherein said patterning process is the photolithography
including resist pattern forming and etching.
26. The manufacturing method of micro-structures as claimed in
claim 19, wherein said first step includes a process in which said
plurality of first thin films are formed and said second thin films
are formed on said substrate on which said plurality of first thin
films are not formed, and then the film thickness of said first
thin films and the second thin films is equalized by polishing the
surface until the film thickness of said first thin films and said
second thin films is made equal.
27. The manufacturing method of micro-structures as claimed in
claim 19, wherein said plurality of composite thin films are bonded
by surface activated bonding in said second step.
28. The manufacturing method of micro-structures as claimed in
claim 19, wherein said second step includes a process for cleaning
the bonding surface of said stage and said plurality of composite
thin films in a vacuum chamber.
29. The manufacturing method of micro-structures as claimed in
claim 28, wherein said cleaning process is a process in which said
bonded surface is irradiated with a particle beam.
30. The manufacturing method of micro-structures as claimed in
claim 19, wherein a sacrifice layer which can be removed after
forming said laminate is formed previously on the surface of said
stage as an interface between said composite thin film and said
stage by laminating said plurality of composite thin films.
31. The manufacturing method of micro-structures as claimed in
claim 19, wherein a releasing layer is formed previously on the
surface of said substrate as an interface between said substrate
and said composite thin film.
32. The manufacturing method of micro-structures as claimed in
claim 31, wherein said releasing layer is formed by vapor
deposition or coating of fluorine-containing material, or by
exposing the surface of said substrate to discharge of a gas
containing fluorine atom to fluoridize the surface of said
substrate.
33. The manufacturing method of micro-structures as claimed in
claim 20, wherein said micro-structure is composed of a plurality
of independent structural elements, and in said first step said
plurality of first thin films are formed so that said plurality of
structural elements which are assembled in the form of said
micro-structure are contained in said laminate when lamination of
said plurality of composite thin films in said second step is
completed.
34. A manufacturing method of micro-structures comprising; a first
step for forming a thin film respectively on a plurality of
substrates and forming a plurality of latent images having a
prescribed two-dimensional pattern on each said thin film formed on
said plurality of substrates, a second step for bonding said thin
films each other on which said latent images are formed, a third
step for removing one substrate out of a pair of said substrates
having said thin films bonded each other, a fourth step for
laminating a plurality of thin films by repeating said second step
and said third step, and a fifth step for developing said latent
images out of said plurality of laminated thin films.
35. The manufacturing method of micro-structures as claimed in
claim 34, wherein said latent images are formed by diffusion of
impurity into said substrate.
36. A manufacturing apparatus of micro-structures provided with a
substrate holder on which a substrate having a plurality of thin
films are formed thereon having a prescribed two-dimensional
pattern provided in a vacuum chamber, a stage disposed facing said
substrate holder in said vacuum chamber for supporting a
three-dimensional structure formed by laminating said plurality of
thin films, moving means for transferring at least either of said
substrate holder and said stage to position said stage successively
on said plurality of thin films, and control means for controlling
said moving means to separate said plurality of thin films from
said substrate, to laminate and bond said plurality of thin films
on said stage so as to form a micro-structure.
37. The manufacturing apparatus of micro-structures as claimed in
claim 36, wherein said moving means is provided with a moving
mechanism for moving relatively said substrate holder and said
stage at least in three axis directions.
38. The manufacturing apparatus of micro-structures as claimed in
claim 36, wherein said vacuum chamber is provided with irradiation
means for applying an atomic beam or ion beam onto the surface of
said stage to be bonded or said thin film in order to clean the
surface.
Description
BACKGROUND OF THE INVENTION
Field of the Invention
[0001] This invention relates to micro-structures such as
micro-gears, micro-optical parts, or molds for molding these
micro-products manufactured by rapid prototyping, and a
manufacturing method and an apparatus thereof, and more
particularly relates to micro-structures obtained by laminating
thin films consisting of a metal or an insulator which are
patterned into sectional forms, and a manufacturing method and an
apparatus thereof.
[0002] Rapid prototyping has been rapidly popularized recently as a
method for molding three dimensional complex form products designed
with aid of a computer within a short time. Three dimensional
products manufactured by rapid prototyping are used as parts models
(prototype) of various apparatus to predict the suitability of
operation or form of parts. This method has been mainly applied to
relatively large parts having a size of several cm or larger,
however, recently it has been desired to apply this method to
manufacture micro-parts formed by precise working such as
micro-gears and micro-optical parts. Conventional methods for
manufacturing such micro-parts described hereinafter have been
known.
[0003] (1) Stereolithography (referred to as "conventional example
1" hereinafter)
[0004] (2) Selective laser sintering (referred to as "conventional
example 2" hereinafter)
[0005] (3) Sheet lamination (referred to as "conventional example
3" hereinafter)
[0006] (4) Method using thin films as starting material (referred
to as "conventional example 4" hereinafter)
[0007] (Convention Example 1)
[0008] FIG. 26 shows the conventional example 1 namely the
stereolithography. In the "stereolithography", photo-curable resin
100, which is hardened by irradiation of light such as ultraviolet
rays, is filled in a tank 101, a laser beam 102 scans on the
surface of the tank 101 two-dimensionally to draw a form
corresponding to the cross-sectional data of a three-dimensional
product to harden the resin layer 100a, then a stage 103 is lowered
by one layer, and this process is repeated layer by layer to form
the three dimensional product comprising a plurality of resin
layers 100a. Stereolithography is presented by Ikuta, Nagoya
University, in a literature "OPTRONICS, 1996, No. 4, p 103".
According to the special stereolithography, planer form precision
of 5 .mu.m and resolution in the lamination direction of 3 .mu.m
can be attained by optimization of exposure conditions and
optimization of resin characteristics. Stereolithography is also
presented by Kawata, Osaka University, in a literature "Proceedings
of MEMS 97, p 169". According to this stereolithography, planer
form precision of 0.62 .mu.m and resolution in the lamination
direction of 2.2 .mu.m can be attained by utilizing a principle of
two-photon absorption phenomenon.
[0009] (Conventional Example 2)
[0010] FIG. 27 shows the conventional example namely selective
laser sintering. In the "selective laser sintering", powder 104 is
laid to form a thin layer (powder layer) 104a, a laser beam 102 is
applied to the powder layer 104a to form a thin layer of a desired
form, and by repeating this process a three dimensional sintered
product composed of a plurality of powder layers 104a is formed.
According to the selective laser sintering, a three dimensional
product not only of resin but also ceramics and metals can be
formed.
[0011] (Conventional Example 3)
[0012] FIG. 28 shows a manufacturing apparatus used in the
conventional example 3 namely the sheet lamination disclosed in
Japanese Published Unexamined Patent Publication No. Hei 6-190929.
In this manufacturing apparatus, when a plastic film 111 is
supplied from a film feeding device 110, an adhesive coating device
120 coats photo-curable adhesive 121 evenly on the underside of the
plastic film 111 to form an adhesive layer, a negative pattern
exposure device 130 exposes an area of the adhesive layer excepting
the area corresponding to the cross sectional form of a
micro-structure to form the hardened portion and the uncured
portion, this is pressed down by a press roller 141 of a
photo-curing laminating device 140, the uncured portion is hardened
by the light from a light source 142 and bonded to the lower
plastic film 111. The rear end of the plastic film 111 is cut by a
laser beam from a CO.sub.2 laser source 151, and the border of the
unnecessary area of the uppermost plastic film 111 is removed by
the laser. This process is repeated layer by layer to form a
micro-structure. In FIG. 28, 160 represents a work device for
controlling this apparatus. According to the sheet lamination, a
micro-structure comprising plastic sheets is obtained.
[0013] (Conventional Example 4)
[0014] FIG. 29 shows the conventional example 4 namely a
manufacturing method using thin films as starting material
disclosed in Japanese Published Unexamined Patent Publication No.
Hei 8-127073. In this manufacturing method, as shown in the drawing
(a), a photosensitive resin film 171 is formed on a substrate 170,
and two processes, namely aprocess for forming an exposed portion
171a by exposing on an area of a desired pattern as shown in the
drawing (b) and a process for forming an intermediate film 172
which prevents the resin film 171 from being mixed and prevents
exposure of the lower layer, are repeated to form a multi-layer
structure composed of the resin film 171 and intermediate film 172
as shown in the drawing (c), and then the exposed portion 171a
shown in the drawings (b) and (c) is selectively removed by dipping
it in a resin developing solution and thus a three dimensional
micro-structure as shown in drawing (d) is obtained. According to
this manufacturing method, the resolution in the lamination
direction of .mu.m order can be attained because spin coating is
applied to the resin film 171 and intermediate film 172.
[0015] However, according to the conventional example 1, namely
stereolithography, this method is disadvantageous in that the
resolution in the lamination direction of 1 .mu.m or smaller and
the film thickness precision of 0.1 .mu.m or smaller, which is
required to manufacture micro-gears and micro-optical parts, cannot
be attained. In detail, because an incident light applied
perpendicularly onto the layer for hardening the starting material
(photosensitive resin) is used, the incident light penetrates
perpendicularly from the surface through the layer with decreasing
intensity due to absorption, and the intensity decreases to the
level of threshold value required for curing. The layer thickness
corresponding to the threshold value is the thickness of one layer,
but because of dispersion of the incident light intensity,
variation of the incident light intensity with time, and dispersion
of the absorption coefficient of the starting material, it is
difficult to obtain high resolution.
[0016] In addition, full cure process is applied to harden
completely after forming because photosensitive resin is used, in
the full cure process the product shrinks 1% through several %, the
shrinkage is disadvantageous and causes significant deterioration
of the precision.
[0017] Furthermore, this method can be applied to only
micro-structures made of relatively soft photosensitive resin,
therefore, if a micro-structure is required to be made of a hard
material such as a metal, the only way to manufacture the product
is the molding by electroforming or injection molding using a mold
of this resin. The requirement of such process is
disadvantageous.
[0018] According to the conventional example 2, namely the
selective laser sintering, the resolution in the lamination
direction is poor because an incident light applied perpendicularly
onto the layer is used as in the conventional example 1, and the
shrinkage in full cure process causes deterioration of precision,
and furthermore the method is disadvantageous in that a transfer
process is required to manufacture micro-structures made of a hard
material such as metal.
[0019] According to the conventional example 3, namely the sheet
lamination, the sheet thickness is the determinant factor of the
resolution in the lamination direction, the lower limit is about
several tens .mu.m in view of usable sheet thickness, and it is
difficult to realize the resolution in the lamination direction of
1 .mu.m.
[0020] According to the conventional example 4, namely the
manufacturing method using thin films as starting material, the
intermediate film (for example A1) is required in order to prevent
exposure of the lower layer because an incident light applied
approximately perpendicularly is used in the exposure process, this
method is disadvantageous in the resolution per one layer. Though a
method in which two types of photosensitive resins of different
sensitive wavelengths and different solubility in solvents are
laminated alternately, the respective photosensitive resins are
exposed, and finally developed to form a three dimensional product
in order to omit the use of the intermediate film, is disclosed in
the patent, because this method is still disadvantageous in that
the adhesion between resins of different solubility in solvents is
poor, the strength of a completed product is low, and the
dimensional precision is poor due to swelling of the photosensitive
resin in the final development process. Furthermore, it is
impossible to apply this method directly to hard material such as
metals and insulators as in the above-mentioned stereolithography
because photosensitive resin is used, and the only way is a method
in which a product is used as a mold.
[0021] Accordingly, it is an object of the present invention to
provide micro-structures of high dimensional precision and,
particularly, high resolution in the lamination direction and a
manufacturing method and an apparatus thereof.
[0022] It is another object of the present invention to provide
micro-structures which are formed directly of metals or insulators
such as ceramics and a manufacturing method thereof and an
apparatus therefor.
[0023] It is yet another object of the present invention to provide
micro-structures which can be formed together from a plurality of
combined structural elements and a manufacturing method and an
apparatus thereof.
SUMMARY OF THE INVENTION
[0024] To achieve the above-mentioned object, the present invention
provides a micro-structure comprising a plurality of laminated thin
films having prescribed two-dimensionally patterned forms.
[0025] To achieve the above-mentioned object, the present invention
provides a manufacturing method of micro-structures composed of a
first step for forming a plurality of thin films having prescribed
two-dimensionally patterned forms on a substrate, and a second step
for forming the micro-structure by separating the plurality of thin
films from the substrate and subsequently by laminating and bonding
the plurality of thin films on a stage.
[0026] To achieve the above-mentioned object, the present invention
provides a manufacturing method of micro-structures including;
[0027] a first step for forming a plurality of first thin films
having a prescribed two-dimensional pattern on a substrate, and
forming a plurality of second thin films composed of different
material from that of the first thin films and having the same film
thickness as the first thin film to form a plurality of composite
thin films comprising the first thin films and the second thin
films,
[0028] a second step for forming a laminate including a
micro-structure by laminating and bonding the plurality of
composite thin films on a stage, and
[0029] a third step for removing the first thin films or the second
thin films out of the substrate to obtain the micro-structure.
[0030] To achieve the above-mentioned object, the present invention
provides a manufacturing method of micro-structures including;
[0031] a first step for forming a thin film respectively on a
plurality of substrates and forming a plurality of latent images
having a prescribed two-dimensional pattern on each thin film
formed on the plurality of substrates,
[0032] a second step for bonding the thin films each other on which
the latent images are formed,
[0033] a third step for removing one substrate out of a pair of
substrates having the thin films bonded each other,
[0034] a fourth step for laminating a plurality of thin films by
repeating the second step and the third step, and
[0035] a fifth step for developing the latent images out of the
plurality of laminated thin films.
[0036] To achieve the above-mentioned object, the present invention
provides a manufacturing apparatus of micro-structures provided
with;
[0037] a substrate holder having a substrate on which a plurality
of thin films are formed thereon having a prescribed
two-dimensional pattern provided in a vacuum chamber,
[0038] a stage disposed facing the substrate holder in the vacuum
chamber for supporting a three-dimensional structure formed by
laminating the plurality of thin films,
[0039] a moving means for transferring at least either of the
substrate holder and the stage to position the stage successively
on the plurality of thin films, and
[0040] a control means for controlling the moving means to separate
the plurality of thin films from the substrate, to laminate and
bond the plurality of thin films on the stage so as to form a
micro-structure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0041] FIG. 1 is a block diagram for illustrating a manufacturing
system in accordance with the first embodiment of the present
invention.
[0042] FIG. 2 is a schematic structural diagram of a lamination
equipment in accordance with the first embodiment.
[0043] FIG. 3 is a block diagram for illustrating a control system
of the lamination device in accordance with the first
embodiment.
[0044] FIG. 4 is a diagram for describing the relation between the
bonding strength of a sacrifice layer, a thin film, and a releasing
layer in the first embodiment.
[0045] FIG. 5 is a perspective view of a target micro-structure of
the first embodiment.
[0046] FIG. 6 is a set of diagrams, FIG. 6(a) shows a thin film
deposition process in accordance with the first embodiment, and
FIG. 6(b) and FIG. 6(b) show the patterning process in accordance
with the first embodiment.
[0047] FIG. 7 is a set of diagrams, FIGS. (a) through (c) show the
lamination process in accordance with the first embodiment.
[0048] FIG. 8 is a set of diagrams, FIGS. (d) through (f) show the
lamination process in accordance with the first embodiment.
[0049] FIG. 9 is a cross-sectional view for showing completion of a
lamination process in accordance with the first embodiment.
[0050] FIG. 10 is a set of diagrams, FIG. 10(a) is an exploded
perspective view of a micro-pulley, namely a micro-structure, and
FIG. 10(b) is a cross-sectional view of the micro-pulley.
[0051] FIG. 11 is a set of diagrams, FIGS. 11(a) through (e) show
the film deposition and patterning process in accordance with the
second embodiment.
[0052] FIG. 12 is a plan view of a substrate for showing the
patterning process in accordance with the second embodiment.
[0053] FIG. 13 is a plan view of a substrate for showing the
patterning process in accordance with the second embodiment.
[0054] FIG. 14 is a cross-sectional view for showing laminated
cross-sectional elements of the first layer through twentieth layer
in accordance with the second embodiment.
[0055] FIG. 15 is a set of diagrams, FIG. 15(a) is an exploded
perspective view of a target micro-gear of the second embodiment,
and FIG. 15(b) is a longitudinal cross-sectional view of the
micro-gear.
[0056] FIG. 16 is a plan view for showing a thin film deposition
substrate in accordance with the third embodiment of the present
invention.
[0057] FIG. 17 is a set of diagrams, FIGS. 17(a) through (d) are
plan views for showing a thin film deposition substrate in
accordance with the third embodiment of the present invention.
[0058] FIG. 18 is a cross-sectional view for showing laminated
chips of the first layer through twentieth layer in accordance with
the third embodiment.
[0059] FIG. 19 is a schematic structural diagram of the patterning
equipment in accordance with the fourth embodiment of the present
invention.
[0060] FIG. 20 is a perspective view of a target micro-structure of
the fourth embodiment.
[0061] FIG. 21 is a plan view of a substrate for showing the
patterning process in accordance with the fourth embodiment.
[0062] FIG. 22 is a cross-sectional view for showing laminated
cross-sectional elements of the first layer through n-th layer in
accordance with the fourth embodiment.
[0063] FIG. 23 is a block diagram for illustrating a manufacturing
system in accordance with the fifth embodiment of the present
invention.
[0064] FIG. 24 is a set of diagrams, FIGS. 24(a) through (d) are
diagrams for showing a manufacturing method in accordance with the
fifth embodiment.
[0065] FIG. 25 is a set of diagrams, FIGS. 15(e) through (h) are
diagrams for showing a manufacturing method in accordance with the
fifth embodiment.
[0066] FIG. 26 is a schematic diagram for illustrating the
stereolithography of the conventional example 1.
[0067] FIG. 27 is a schematic diagram for illustrating the
selective laser sintering of the conventional example 2.
[0068] FIG. 28 is a diagram for illustrating a manufacturing
apparatus in accordance with the sheet lamination of the
conventional example 3.
[0069] FIG. 29 is a set of diagrams, FIGS. 29(a) through (d) show a
manufacturing method of the conventional example 4 in which thin
films are used as starting material.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0070] FIG. 1 shows a manufacturing system of micro-structures in
accordance with the first embodiment of the present invention. The
structure of this manufacturing system 1 comprises a film
deposition equipment 2A for depositing a thin film on a substrate,
a patterning equipment 2B for patterning a pattern on the thin film
formed by the film deposition equipment 2A corresponding to
cross-sectional forms of an object micro-structure, and a
lamination equipment 3 for laminating a plurality of patterned thin
films by surface activated bonding.
[0071] The film deposition equipment 2A controls excellently the
film thickness of a film deposited on a substrate such as an Si
wafer, a quartz substrate, or a glass substrate (for example,
Corning 7059) in a thickness range from sub .mu.m through several
.mu.m, and forms a thin film by, for example, vacuum vapor
deposition such as electron beam deposition, resistance heating
vapor deposition, sputtering, or chemical vapor deposition (CVD),
or spin coating which gives a film with even thickness through the
entire substrate. By applying vacuum vapor deposition or spin
coating, a film with a thickness of 0.1 through 10 .mu.m is
deposited with a film thickness precision of {fraction (1/10)} the
film thickness or smaller.
[0072] The film deposition equipment 2A previously forms a
releasable releasing layer on the surface of a substrate prior to
deposition or coating of a thin film. The releasing layer may be a
thin film of thermal oxide or fluorine-containing resin formed by
vapor deposition or coating on the surface of a substrate, or may
be formed by a method that the substrate surface is exposed to
discharge in a gas containing fluorine to fluoridize the substrate
surface. The releasability is enhanced by forming a thin film
containing fluorine or fluoridation.
[0073] The patterning equipment 2B forms a plurality of thin films
having forms respectively corresponding to each cross-sectional
form of a micro-structure by removing unnecessary portions or
circumference together using a patterning method for patterning
with a planer precision within 0.1 .mu.m, for example,
photolithography, focused ion beam method (FIB), or electron beam
lithography. By applying lithography, the planer precision of sub
.mu.m is obtained, and the productivity is enhanced. By applying
FIB method and electron beam lithography, the planer precision of
sub .mu.m is obtained, and a film is patterned without using a
photo-mask because an arbitrary form is drawn by beam scanning,
hence the time for manufacturing of photomasks is saved. In the
case of the electron beam lithography, electron beam resist which
is sensitive to an electron beam is used as the resist. In the
first embodiment, unnecessary portions are removed by
photolithography.
[0074] FIG. 2 shows a schematic structure of the lamination
equipment 3. The lamination equipment 3 is provided with a vacuum
chamber 300 in which lamination process is performed, and in the
vacuum chamber 300, a substrate holder 301 on which a substrate 400
is placed and fired, a stage 302 to which a thin film formed on the
substrate 400 is transferred, the first FAB source 303A for FAB
(Fast Atom Bombardment) of the stage 302 side and the second FAB
source 303B for FAB of the substrate 400 side both attached to the
stage 302, the first and second withdrawing motors 305A and 305B
for withdrawing the first and second FAB sources 303A and 303B by
rotating arms 304A and 304B about 90.degree. after FAB, a mark
detection unit 306 for detecting an alignment mark on the substrate
400 as a microscope mounted on the stage 302, a vacuum gauge 307
for measuring the degree of vacuum in the vacuum chamber 300, an
X-axis table 310 for moving the stage 302 in the X-axis direction
(horizontal direction in FIG. 2) using an X-axis motor 311 (refer
to FIG. 3) and for detecting the position of the stage 302 on the
X-axis using an X-axis position detection unit 312 (refer to FIG.
3), and a Y-axis table 320 for moving the stage 302 in the Y-axis
direction (in the direction perpendicular to the page plane) using
a Y-axis motor 321 (refer to FIG. 3) and for detecting the position
of the stage 302 on the Y-axis are provided. Herein, "FAB" means a
treatment that, for example, argon gas which is accelerated by a
high voltage of about 1 kV is applied onto the surface of a
material as an atom beam to remove oxide film and impurities on the
material surface and to clean the surface. In this embodiment, the
FAB irradiation conditions are varied depending on material to be
treated, in detail, the acceleration voltage is varied in a range
from 1 through 1.5 kV, and irradiation time is varied in a range
from 1 to 10 minutes.
[0075] The stage 302 consists of a metal such as stainless steel or
aluminum, and a sacrifice layer is formed previously on the surface
in order to separate the microstructure easily from the stage 302
the micro-structure comprising a plurality of thin films laminated
on the stage 302. Material used for the sacrifice layer is selected
depending on the material of the micro-structure. In detail, for
the micro-structure made of a metal such as aluminum, copper or
nickel is selected as the material of the sacrifice layer, and in
this case, a copper or nickel layer with a thickness of, for
example, about 5 .mu.m is formed on the surface of the stage 302 by
plating. For the micro-structure which comprises thin films of an
insulator, namely ceramics such as alumina, aluminum nitride,
silicon carbide, or silicon nitride, aluminum is selected as the
material of the sacrifice layer, and in this case, an aluminum
layer is formed on the surface of the stage 302 by vacuum vapor
deposition. By removing only the sacrifice layer after completion
of thin film lamination, the micro-structure is separated easily
from the stage 302 without an external force applied to the
micro-structure.
[0076] The lamination equipment 3 is provided with a Z-axis table
330, a e table 340, a vacuum pump 350, an argon gas cylinder 351,
and the first and second flow rate controllers (MFC) 353A and 353B.
The Z-axis table 330 is served for moving the substrate holder 301
in the Z-axis direction (vertical direction in FIG. 2) to the
outside of the vacuum chamber 300 using a Z-axis motor 331 (refer
to FIG. 3), for pressing the thin film onto the stage 302 side with
a pressure of 5 kgf/cm.sup.2 or higher for 1 through 10 minutes,
and for detecting the position of the substrate holder 301 on the
Z-axis using a Z-axis position detection unit 332 (refer to FIG. 3)
The .theta. table 340 is served for rotating the substrate holder
301 round the Z-axis using a .theta. motor 341 for alignment
adjusting, and for detecting the angular position in the
.theta.-direction of the substrate holder 301 using a .theta.
position detection unit 342 (refer to FIG. 3). The vacuum pump 350
is served for evacuating the internal of the vacuum chamber 300 to
a vacuum. The argon gas cylinder 351 contains argon gas. The first
and second mass flow controllers (MFC) 353A and 353B is served for
controlling the flow rate of argon gas supplied from the argon gas
cylinder 351, and for supplying argon gas to the first and second
FAB sources 303A and 303B through the first and second solenoid
valves 352A and 352B.
[0077] FIG. 3 shows a control system of the lamination equipment 3.
The lamination equipment 3 has a control unit 360 for controlling
this equipment 3 wholly, and the control unit 360 is connected to
various units namely a memory 361 for storing various information
including programs of the control unit 360, the first FAB source
303A via the first FAB source driving unit 362A, the second FAB
source 303B via the second FAB source driving unit 362B, the first
and second withdrawing motors 305A and 305B, the mark detection
unit 306, the vacuum gauge 307, the X-axis motor 311, the X-axis
position detection unit 312, the Y-axis motor 321, the Y-axis
position detection unit 322, the Z-axis motor 331, the Z-axis
position detection unit 332, the .theta. motor 341, the
.theta.position detection unit 342, the vacuum pump 350, the first
and second solenoid valves 352A and 352B, and first and second MFCs
353A and 353B.
[0078] For example, a laser interferometer or glass scale may be
used as the X-axis position detection unit 312, the Y-axis position
detection unit 322, and the .theta. position detection unit
342.
[0079] The first and second FAB source driving units 362A and 362B
supply an acceleration voltage of 1 though 1.5 kV to the
corresponding first and second FAB sources 303A and 303B.
[0080] The control unit 360 controls respective units in the
lamination equipment 3 to perform the process in which the thin
film formed on the substrate 400 with interposition of the
releasing layer is bonded on the surface of the stage 302 with
interposition of the sacrifice layer, a plurality of thin films
separated from the substrate are bonded and laminated successively
on the thin film to form a micro-structure based on programs stored
in the memory 361.
[0081] FIG. 4 shows a diagram for describing the bonding strength
between the sacrifice layer, thin film, and releasing layer.
Assuming that the bonding strength between the releasing layer 401
and the thin layer 4a is represented by f.sub.1, the bonding
strength between thin films 4a and 4a is represented by f.sub.2,
and the bonding strength between the thin film 4a and the sacrifice
layer 370 is represented by f.sub.3, then the material of the
sacrifice layer 370, releasing layer 401, and thin film 4a is
selected so that the order of the strength is in the relation
f.sub.2>f.sub.3>f.sub.1. As the result, the thin film 4a
formed on the substrate 400 with interposition of the releasing
layer 401 is bonded to the sacrifice layer 370 on the stage 302 or
bonded to the thin film 4a transferred already on the stage 302
with sufficient strength, and can be separated from the substrate
400 and transferred to the stage 302 side.
[0082] Next, operations of the manufacturing system 1 in accordance
with the first embodiment are described with reference to FIG. 5
and FIG. 6. Herein it is assumed that the sacrifice layer 370 is
formed previously on the stage 302.
[0083] FIG. 5 shows one example of a micro-structure to be
manufactured in the first embodiment. The micro-structure 4
comprises a plurality of thin films 4a respectively corresponding
to each cross-sectional form.
[0084] FIGS. 6(a) through (c) show a film deposition process and
patterning process.
[0085] (1) Film deposition
[0086] As shown in FIG. 6(a), by using the film deposition
equipment 2A, a thermal oxide film with a thickness of 0.1 .mu.m is
grown on the surface of a substrate 400 namely an Si wafer as the
releasing layer 401, and an Al thin film 402 with a thickness of
0.5 82 m is formed on the thermal oxidized film by spattering. High
purity Al is used for a sputtering target, the sputtering pressure
is 0.5 Pa and the temperature of the substrate is a room
temperature. The film thickness is monitored continuously by a
quartz oscillator film thickness meter during film deposition, the
film deposition process terminates when the film thickness reaches
0.5 .mu.m. As the result, the film thickness on the substrate 400
with distribution within 0.5.+-.0.02 .mu.m is obtained. The film
thickness is the determinant of the resolution in the lamination
direction of the micro-structure obtained finally, and sufficient
attention should therefore be paid to the film thickness and film
thickness distribution.
[0087] (2) Patterning
[0088] As shown in FIGS. 6(b) and 6(c), a plurality of thin films
4a respectively corresponding to each cross-sectional form of the
micro-structure 4 shown in FIG. 5 is formed by photolithography. in
detail, positive type photo-resist is coated on the surface of the
A1 thin film 402 formed on the substrate 400, the photo-resist is
exposed to light with covering by a photo-mask (omitted from the
drawing), the exposed portion of the photo-resist is removed by a
solvent, the exposed portion of the thin film 402 is etched, and
the unexposed photo-resist is removed by a resist remover leaving
the plurality of thin films 4a on the substrate. When, a plurality
(for example three) of alignment marks 403 for positioning the
substrate 400 in patterning process is also formed. In FIGS. 6(b)
and 6(c), the respective thin films 4a are designated as the first
layer through the sixth layer in order of diameter from the largest
one through smallest one for the purpose of description.
[0089] FIGS. 7(a) through 7(c) and FIGS. 8(d) through 8(f) the
lamination process described hereinafter. In FIG. FIG. 8, the
releasing layer 401 and sacrifice layer 370 are omitted from the
drawings.
[0090] (3) Introduction of the substrate 400 into the vacuum
chamber 300
[0091] The substrate 400 on which the plurality of thin films 4a
are formed is placed and fired on the substrate holder 301 in the
vacuum chamber 300 of the lamination equipment 3.
[0092] (4) Evacuation of the internal of the vacuum chamber 300
[0093] When an operator pushes down a starting switch (not shown in
the drawing) of the lamination equipment 3, the control unit 360
performs the process described hereinafter according to the program
stored in the memory 361. First, the control unit 360 controls the
vacuum pump 350 based on the vacuum value detected by the vacuum
gauge 307 to evacuate the internal of the vacuum chamber 300 to
10.sup.-6 Pa, and the internal of the vacuum chamber 300 is brought
to the condition of high vacuum or ultra-high vacuum.
[0094] (5)Alignment adjustment
[0095] After the evacuation, the control unit 360 performs
alignment adjustment of the stage 302 and the substrate 400
(alignment mark 403). In detail, the control unit 360 controls the
X-axis motor 311 and the Y-axis motor 321 so as to fetch a mark
detection signal from the mark detection unit 306 by moving the
stage 302 in the X-direction and Y-direction, measures the relative
positional relation between the substrate 400 and substrate holder
301 based on the mark detection signal, and controls the X-axis
motor 311, the Y-axis motor 321, and the motor .theta. 341 so that
the stage 302 and alignment mark 403 reach the original position
based on the measurement result of the relative position relation.
The stage 302 is moved in the X-direction and the Y-direction
respectively by the X-axis motor 311 and the Y-axis motor 321, the
substrate holder 301 is rotated by the .theta. motor 341, and the
stage 302 and alignment mark 403 reach the original position.
Hence, even though the position where the substrate 400 on which
the thin films 4a are formed is placed deviates from the correct
position, the relative position between the stage 302 and the
alignment mark 403 is set correctly.
[0096] (6) Removal of the contaminated layer on the surface to be
bonded to the first layer thin film 4a
[0097] As shown in FIG. 7(a), the control unit 360 drives the
X-axis motor 311 and the Y-axis motor 321 based on the detection
signal of the X-axis position detection unit 312 and the Y-axis
position detection unit 322, and moves the stage 302 from the
original position in the X-direction and Y-direction to position
the stage 302 on the first layer thin film 4a. Then the control
unit 360 irradiates an argon atomic beam 351a onto the surface (the
surface of the stage 302 and the surface of the first layer thin
film 4a) where the first layer thin film 4a is to be bonded for FAB
treatment. In detail, the control unit 360 performs driving control
on the first and second FAB source driving units 362A and 362B,
operation control on the first and second solenoid valves 352A and
352B, and flow rate control on the first and second MFCs 353A and
353B so that the argon atomic beam 351a is applied onto the surface
of the stage 302 and the surface of the first layer thin film 4a
with a prescribed rate for a prescribed time (for example, 5
minutes). The first and second FAB source driving units 362A and
362B are controlled by the control unit 360 so as to provide an
acceleration voltage of, for example, 1.5 kV to the first and
second FAB sources 303A and 303B. The flow rate of argon gas
supplied from the argon gas cylinder 351 is controlled by the first
and second MFCs 353A and 353B, and argon gas is supplied to the
first and second FAB sources 303A and 303B through the first and
second solenoid valves 352A and 352B. The first FAB source 303A
irradiates the argon atomic beam 351a for 5 minutes onto the
surface of the stage 302 which is located off the upper direction
at an angle of about 45.degree.. The second FAB source 303B
irradiates the argon atomic beam 351a for 5 minutes onto the
surface or the first layer thin film 4a which is located off the
lower direction at an angle of about 45.degree.. The contaminated
layers with a thickness of less than 10 nm on the surface of the
stage 302 and the first thin film 4a are removed thereby. Such
small thickness decrement can be neglected because the number of
decrement is one figure smaller than the target film thickness
precision of 0.1 .mu.m of the present invention.
[0098] (7) Bonding of the first layer thin film 4a
[0099] Next, as shown in FIG. 7(b), the control unit 360 drives the
first and second withdrawing motors 305A and 305B to rotate the
arms 304A and 304B in the horizontal direction, and withdraws the
first and second FAB sources 303A and 303B. The control unit 360
controls the Z-axis motor 331 based on the detection signal of the
Z-axis position detection unit 332 to elevate the substrate holder
301, the surface of the first layer thin film 4a is forced to be in
contact with the surface of the stage 302, and the contact
continues for a prescribed time (for example, 5 minutes) with a
prescribed pressure (for example, 50 kgf/cm.sup.2). The surface of
the first layer thin film 4a is bonded to the surface of the stage
302 (sacrifice layer 370) strongly. A tensile test for evaluation
of the bonding strength between the thin film 402 and the sacrifice
layer 370 shows 50 through 100 Mpa. Preferable surface roughness of
the thin film 4a and stage 302 is respectively about 10 nm for
obtaining excellent bonding strength.
[0100] (8) Transfer of first layer thin film 4a
[0101] Next, as shown in FIG. 7(c), the control unit 360 drives the
Z-axis motor 331 based on the detection signal of the Z-axis
position detection unit 332 to lower the substrate holder 301 to
the original position shown in FIG. 7(a), and drives the first and
second withdrawing motors 305A and 305B to return the first and
second FAB sources 303A and 303B to the original position. By
lowering the substrate holder 301, the thin film 4a is separated
from the substrate 400 and transferred to the stage 302 side
because the bonding strength f.sub.3 between the thin film 4a and
the sacrifice layer on the stage 302 is larger than the bonding
strength f.sub.1 between the thin film 4a and the releasing
layer.
[0102] (9) Removal of a contaminated layer on the surface to be
bonded to the second layer thin film 4a
[0103] Next, as shown in FIG. 8(d), the control unit 360 controls
the X-axis motor 311 and the Y-axis motor 321 to move the stage 302
above the second layer thin film 4a, and irradiates again FAB as
described in FIG. 7(a). The moving distance of the stage 302 is a
distance corresponding to each thin film 4a pitch. This FAB
irradiation is different from the first FAB irradiation in that the
back surface of the first layer thin film 4a (the surface which has
been in contact with the substrate 400) is irradiated for cleaning
instead of the surface of the stage 302.
[0104] (10) Bonding of the second layer thin film 4a
[0105] Next, as shown in FIG. 8(e), the control unit 360 withdraws
the first and second FAB sources 303A and 303B, elevates the
substrate holder 301 to bond the second layer thin film 4a to the
first layer thin film 4a.
[0106] (11) Transfer of the second layer thin film 4a
[0107] Next, as shown in FIG. 8(f), the control unit 360 lowers the
substrate holder 301, returns the first and second FAB sources 303A
and 303B to the original position, and lowers the substrate holder
301. By lowering the substrate holder 301, the second layer thin
film 4a is separated from the substrate 400 side and transferred
onto the first thin film 4a because the bonding strength f.sub.2
between thin films is larger than the bonding strength f.sub.1
between the thin film 4a and the releasing layer 401.
[0108] (12) Removal of the sacrifice layer 370
[0109] FIG. 9 shows the state that all the thin films 4a have been
laminated. By repeating bonding and transferring of thin films 4a
of third layer through sixth layer successively, a micro-structure
4 comprising all the laminated thin films 4a is obtained. Finally
the sacrifice layer 370 is removed by etching and the
micro-structure 4 is separated from the stage 302.
[0110] The effect of the above-mentioned first embodiment is
described hereinafter,
[0111] (a) A plurality of thin films 4a which are components of a
micro-structure are formed simultaneously together by film
deposition and patterning, the plurality of thin films 4a are
laminated therefore simply by repeating bonding and transfer
processes, thus the productivity is enhanced significantly.
Micro-structures are manufactured efficiently because once the
vacuum chamber 300 is evacuated, a set of irradiation of FAB,
bonding, and transfer processes can be performed continuously
without breaking the vacuum.
[0112] (b) A plurality of thin films corresponding to each
cross-sectional form of a micro-structure is formed together by one
process of film deposition and patterning, it is therefore possible
to save the time required for the whole process significantly.
[0113] (c) By injection molding of plastics using the obtained
micro-structure 4 as a mold, micro-optical parts such as optical
lenses are mass-produced.
[0114] (d) Because the thin film 4a is bonded to the stage 302 side
by surface activated bonding, it is not necessary to use an
adhesive or to dissolve the material, and therefore the form and
thickness of the thin film 4a will not change when bonding, thus
high precision is maintained.
[0115] In this embodiment, thin films are bonded by surface
activated bonding, however, the thin films may be bonded by bonding
with an adhesive, or diffusion bonding with heating.
[0116] In this embodiment, the thin films are patterned after film
deposition, however, alternatively, a simultaneous film deposition
and patterning, for example, a method using a metal mask, or
selective CVD may be used.
[0117] In this embodiment the Al thin film is formed by spattering,
however alternatively, the Al thin film may be formed by resistance
heating vapor deposition or electron beam heating vapor
deposition.
[0118] Further, the material used for the thin film is not limited
to Al, but alternatively other metals such as tantalum (Ta),
copper, or indium may be used, and ceramics such as alumina,
aluminum nitride, silicon carbide, or silicon nitride may also be
used.
[0119] In this embodiment the case that the substrate holder 301 is
moved in the Z-direction, and the stage 302 is moved in the
X-direction and the Y-direction is described, however, a case that
both the substrate holder 301 and the stage 302 are moved in the
Z-direction, a case that the substrate holder 301 is moved in the
X-direction and the Y-direction, and the state 302 is moved in the
Z-direction, or a case that the substrate holder 301 and the stage
302 have the same structure may be used.
[0120] A set of processes of film deposition, patterning, bonding,
and transferring may be repeated on every thin film 4a.
[0121] Next, a manufacturing system in accordance with the present
invention will be described hereinafter. The manufacturing system
is provided with a film deposition equipment, a patterning
equipment, and a lamination equipment like the first embodiment,
but different in that the film deposition equipment and patterning
device are structured so as to form a plurality of first thin films
corresponding to each cross sectional form of a micro-structure by
a lift off method, and different in that a polishing device not
shown in the drawing for polishing the surface of a substrate by
CMP (Chemical Mechanical Polishing) is provided in order to form
the second thin film made of the different material from that of
the first thin film and having the same thickness as that of the
first thin film around the first thin film.
[0122] Next, operations of the manufacturing system in accordance
with the second embodiment is described with reference to FIG. 10
and FIG. 11 hereinafter.
[0123] FIG. 10 shows a micro-pulley namely micro-structure 4 to be
manufactured in the second embodiment, FIG. 10(a) is an exploded
perspective view and FIG. 10(b) is a longitudinal cross-sectional
view. The micro-structure 4 shown in the drawing is composed of the
first layer through twentieth alumina thin films 4a, and has a
structure that a shaft 41 provided with flanges 40 and 40 on both
ends thereof is inserted into an opening 43a of the pulley 43
provided with collars 42 and 42.
[0124] FIG. 11 shows film deposition and patterning processes.
[0125] As shown in FIG. 11(a), by using the film deposition
equipment, a thermal oxide film with a thickness of 0.1 .mu.m is
grown on the surface of the substrate 400 namely an Si wafer as the
releasing layer 401. Then, photo-resist 404 is coated on the
releasing layer 401 over the entire surface, portion of the
photo-resist corresponding to each cross-sectional form of the
micro-structure 4 is separated by patterning of exposure and
development, and the first thin film 402A with a thickness of 1
.mu.m made of alumina (Al.sub.2O.sub.3) is deposited over the
entire surface using the film deposition equipment.
[0126] Next, as shown in FIG. 11(b), the residual photo-resist 404
is removed together with the first thin film 402A formed thereon
(lift off method). The residual first thin film 402A is the thin
film 4a to be the component of the micro-structure 4.
[0127] Then, as shown in FIG. 11(c), the second thin film 402B
consisting of aluminum (Al) with a thickness of 1.1 .mu.m is formed
by spattering using the film deposition equipment. At this stage,
the first thin film 402A is covered over the entire surface with
the second thin film 402B. In this embodiment, the combination of
the first thin film 402A of Al.sub.2O.sub.3 and the second thin
film 402B of Al is selected because these materials are bonded
easily each other by surface activated bonding and selectively
removable.
[0128] Next, as shown in FIG. 11(d), the surface of the second film
402B is polished to remove the second thin film 402B by CMP method
using the polishing equipment until the first thin film 402A (4a)
is revealed. The thickness of both the Al.sub.2O.sub.3 thin film
and Al thin film 402B becomes 1 .mu.m. The surface roughness of the
Al.sub.2O.sub.3 thin film 4a is about 10 nm like the stage 302. The
roughness helps obtain a high bonding strength f.sub.2 between the
thin films 4a and 402B.
[0129] FIG. 12 is a plan view corresponding to FIG. 11(d). During
pattern forming shown in FIG. 12, a plurality (for example, three)
of alignment marks 403 are formed.
[0130] Further, as shown in FIG. 11(e), the second thin film 402B
between each pattern is removed by normal photolithography or
scribing using the patterning device to form a partition groove
405, and each cross-sectional element 4b is separated.
[0131] FIG. 13 is a plain view corresponding to FIG. 11(e). The
thin film 4a and the second thin film 402B both having the same
thickness which are to be components of the micro-structure 4 are
now arranged. In this embodiment, every cross-sectional element 4b
which is to structure one micro-structure 4 is arranged regularly
in rows and columns.
[0132] Next, as in the first embodiment, the substrate 400 on which
a plurality of thin films 4a are formed is introduced into the
vacuum chamber of the lamination equipment, and then evacuation of
the vacuum chamber, alignment adjustment, removal of contaminated
layers, thin film bonding, and transfer are performed.
[0133] FIG. 14 shows a laminated layer comprising the first layer
cross-sectional element 4b through the twentieth layer
cross-sectional element 4b. In this drawing, the shaded portion
shows the thin film 4a consisting of Al.sub.2O.sub.3 and the
non-shaded portion shows the second thin film 402B consisting of
Al. By repeating the above-mentioned processes, the cross-sectional
elements 4b of the first layer through twentieth layer are
laminated on the stage 302 with interposition of the sacrifice
layer 370. When the lamination is completed, the appearance is
seemed to be a rectangular parallelepiped of Al, and the pulley 43,
the shaft 41 and two fringes 40 consisting of Al.sub.2O.sub.2 are
imbedded internally. Finally, the Al rectangular parallelepiped is
soaked in an etching solution for dissolving Al to remove only the
second thin film 402B consisting of Al, and the sacrifice layer 370
is removed, hence the micro-pulley 43 combined with the shaft 41
consisting of Al.sub.2O.sub.3 is completed.
[0134] According to the second embodiment, effects described
hereinafter are obtained.
[0135] (a) As shown in FIG. 10, amicro-structure comprising a
plurality of complex combined parts can be manufactured. Because
the first thin film 4a of Al.sub.2O.sub.3 and the second thin film
402B of Al having the same thickness are laminated simultaneously,
the micro-structure can be laminated correctly even though the
micro-structure 4 has an overhang portion (A in FIG. 10(b)) or
separate portion (B in FIG. 10(b), further the small gap (G in FIG.
10(b)) between the shaft 41 and pulley 43 is maintained
correctly.
[0136] (b) A micro-structure in the form of a micro-gear can be
manufactured.
[0137] FIG. 15 shows a micro-gear, FIG. 15(a) is an exploded
perspective view, and FIG. 15(b) is a longitudinal cross-sectional
view. The micro-structure 4 shown in FIG. 15 is composed of thin
films 4a of the first layer through twentieth layer and the
micro-structure has a structure that a shaft 41 provided with
flanges 40 and 40 on both sides is inserted into an opening 43a of
the micro-gear 44.
[0138] (c) Not only can a micro-structure consisting of a metal or
an insulator be formed directly but also a micro-structure having a
complex structure comprising a plurality of combined components can
be manufactured, and assembling work for manufacturing
micro-structures is significantly reduced.
[0139] In this embodiment, the case that combination of ceramics
and metal namely Al.sub.2O.sub.3 for the first thin film and Al for
the second thin film is described, however, alternatively,
combinations, for example, a combination of a metal and a ceramics
such as Al and Al.sub.2O.sub.3, a combination of a metal and
another metal such as Ta and Al, or, Al and Cu, and a combination
of two kinds of ceramics such as alumina and silicon nitride, may
be used. This combination is determined by considering the
bondability each other and capability of selective etching.
[0140] CMP method is used in this embodiment, however, a method in
which a thin film is deposited under precise thickness control and
the exclusive pattern having the same film thickness is formed by
patterning through two photolithography may be used.
[0141] The second thin film is removed by etching after all the
cross-sectional elements 4b are laminated in this embodiment,
however, a method in which the first thin film is formed of a
material which is easy to remove and then the first thin film is
removed may be used. A mold composed of the second thin film having
an inside configuration complementary to the target micro-structure
is obtained thereby, and then micro-structures consisting of
plastics can be mass-produced by injection molding, cast molding,
or press molding using this mold.
[0142] FIG. 16 and FIG. 17 show a thin film deposition substrate in
accordance with the third embodiment. The thin films 4a of the
first layer through twentieth layer are formed continuously and
separately on the substrate 400 in the second embodiment, but in
the third embodiment 148 chips having a size of 10 mm square is
formed on one silicon wafer having a size of 6 inches, and about
7,000 thin films 4a having the same thickness are arranged
two-dimensionally with a 120 .mu.m pitch on each chip C. In FIG.
16, a pattern shown in FIG. 17(a) is formed on respective chips
C.sub.1, C.sub.2, C.sub.19, and C.sub.20, a pattern shown in FIG.
17(b) is formed on respective chips C.sub.3 and C.sub.18, a pattern
shown in FIG. 17(c) is formed on respective chips C.sub.4, C.sub.5,
C.sub.6, C.sub.15, C.sub.16, and C.sub.17, and a pattern shown in
FIG. 17(d) is formed on respective chips C.sub.7 through
C.sub.14.
[0143] FIG. 18 shows a laminated layer of chips C composed of the
first layer to twentieth layer. The second thin film 402B in the
chip C is removed and the sacrifice layer 370 is removed by
etching, thereby 7,000 micro-structures 4 shown in FIG. 10 are
obtained simultaneously, 49,000 micro-structures 4 are obtained
from one wafer, as the result, micro-structures can be
mass-produced. In this embodiment, an embodiment that one type of
micro-structures is arranged in a chip, but a plurality of
different types of micro-structures having different flange
diameters and pulley diameters may be arranged.
[0144] FIG. 19 shows a patterning equipment 2B in accordance with
the fourth embodiment of the present invention. The fourth
embodiment has the same structure as the first embodiment excepting
the patterning equipment 2B. The patterning equipment 2B has a
vacuum chamber 20, and in the vacuum chamber 20 an ion beam
generator 22 and a deflection electrode 23 for deflecting an ion
beam 21 emitted from the ion beam generator 22 based on slice data
of the micro-structure are provided, a thin film 402 is formed on a
substrate 400 with interposition of a releasing layer 401 as shown
in FIG. 19, then the substrate 400 on which the thin film 402 is
formed is introduced into the vacuum chamber 20, and unnecessary
portions or circumference of the thin film 402 is removed by
focused ion beam (FIB) method. In this embodiment, circumference is
removed. "FIB method" generally means a method that vapor of
gallium (Ga) is accelerated by an electric field and focused to a
thin beam, and the beam is scanned by applying a voltage to a
deflection electrode and applied onto desired portions on the
target, such a method is generally used for analysis or observation
of a sample or used for fine working as in this embodiment.
[0145] Next, operations in this embodiment is described with
reference to FIG. 20.
[0146] FIG. 20 shows a micro-structure 4 to be manufactured in the
fourth embodiment. The micro-structure 4 has a drum configuration
composed of thin films first layerto n-th layer. As in the first
embodiment, a releasing layer 401 is formed on a substrate 400, and
an Al thin film 402 having a thickness of 0.5 .mu.m is deposited.
Next, as shown in FIG. 19, the substrate 400 is introduced into the
vacuum chamber 20, and the Al thin film 402 is selectively removed
by FIB method. Though not only the Al layer is removed but also the
substrate surface is slightly removed because the etching in the
depth direction is controlled not so precisely in removal process
by FIB method, the slight removal of the substrate 400 causes no
problem because of no micro-parts in the lower layer.
[0147] FIG. 21 is aplan view for showing the structure after
patterning. In the drawing, 405 is a partition groove formed by FIB
method. The form of patterning is that regions S.sub.1, S.sub.2,
S.sub.3, S.sub.4, . . . having respective forms corresponding to
each cross-sectional form of the micro-structure 4 are arranged
with a space between them in the respective cross-sectional
elements 4b. A cross-sectional element 4b has an arbitrary form
with a size larger than the maximum cross-sectional area of the
micro-structure 4 to be manufactured, and is rectangular in this
embodiment. Cross-sectional elements 4b each of which has a
cross-sectional pattern of the micro-structure to be manufactured
are arranged two-dimensionally on the entire surface of the
substrate 400.
[0148] Following the process described herein above, the substrate
on which a plurality of cross-sectional elements 4b are formed is
introduced into the vacuum chamber 300 of the lamination equipment
3, and by repeating processes of bonding and transfer the
micro-structure 4 composed of the plurality of laminated
cross-sectional elements 4b is completed.
[0149] FIG. 22 shows laminated cross-sectional elements 4b of the
first layer though the n-th layer. The micro-structure 4 composed
of central regions S.sub.1, S.sub.2, S.sub.3, S.sub.4, . . . of the
respective cross-sectional elements 4b is obtained by
etching-removing the sacrifice layer 370.
[0150] According to the above-mentioned fourth embodiment, because
FIB thin film patterning allows the process to be performed without
a photo-mask for patterning the thin films, the time required for
manufacturing is shortened. The pressure can be kept constant when
laminating thin films because the areas of all the cross-sectional
elements 4b are substantially the same. only the grid region for
separating each cross-sectional element 4b and the border region in
each cross-sectional element 4b are removed, and therefore the time
required for processing is saved. The drawing precision of about
0.1 .mu.m is obtained, precise forming of a micro-structure is
realized.
[0151] FIB is used in the above-mentioned embodiment, however,
alternatively, an electron beam may be used.
[0152] FIG. 23 shows a manufacturing system of micro-structures in
accordance with the fifth embodiment of the present invention. The
manufacturing system 1 is provided with a film deposition equipment
2A for depositing a thin film on a substrate, an ion implantation
device 2C for implanting ions onto a region corresponding to each
cross-sectional form of a target micro-structure out of thin films
formed by the film deposition equipment 2A, and a lamination
equipment 3 for laminating onto a plurality of regions where ions
are implanted by surface activated bonding with irradiation of FAB
in the vacuum chamber.
[0153] Next, operations in the manufacturing system 1 in accordance
with the fifth embodiment are described with reference to FIG. 24
and FIG. 25.
[0154] FIG. 24(a) through FIG. 25(d) and FIG. 25(e) through FIG.
25(h) are drawings to show the manufacturing processes in
accordance with the fifth embodiment.
[0155] As shown in FIG. 24(a), a releasing layer 401 of an
SiO.sub.2 film is formed on the surface of the substrate of a
silicon wafer using the film deposition equipment 2A, and a
non-doped polycrystalline Si (poly-Si) thin film 410 is formed
thereon by low pressure chemical vapor deposition (LPCVD). Because
the final micro-structure is formed from the poly-Si thin film 410,
sufficient attention should be paid to the film thickness and film
thickness distribution. In this embodiment, the poly-Si thin film
410 with a thickness of 1.0.+-.0.02 .mu.m is formed. An SOI wafer
(Silicon On Insulator) may be used instead of the Sio.sub.2 film
and poly-Si thin film 410 formed on the substrate 400. Next, a
silicon nitride film 411 with a thickness of 0.5 .mu.m is formed on
the surface of the poly-Si thin film 410 by LPCVD, and a window
411a corresponding to the cross-sectional form of the
micro-structure is provided by the conventional
photolithigraphy.
[0156] Next, as shown in FIG. 24(b), the substrate 40 is introduced
into the ion implantation equipment 2c, boron (B) is implanted up
to a high concentration, for example, of 3.times.10E19[cm.sup.-3]
or higher. After an implanted mask is removed, annealing is
performed in a nitrogen atmosphere to change the ion implanted
region to a high concentration p.sup.+ Si region 410a namely
impurity diffused region, which is served as a latent image.
[0157] As the result, as shown in FIG. 24(c), the substrate 400
having a structural portion of the micro-structure comprising
p.sup.+ Si region 410a and a peripheral portion comprising
non-doped Si region 410 is completed.
[0158] Substrates 400 shown in FIG. 24(c) required to form the
micro-structure are prepared by applying the above-mentioned
process to thin films corresponding to other cross-sectional forms
of the micro-structure.
[0159] Next, as shown in FIG. 24(d), the substrate 400 on which
p.sup.+ Si region 410a corresponding to the cross-sectional form of
the first layer and the substrate 400 on which p.sup.+ Si region
410a corresponding to the cross-sectional form of the second layer
are bonded together. In detail, two substrates 400 and 400 are
introduced into the vacuum chamber of the lamination equipment 3,
the surface is cleaned by FAB irradiation as in the first
embodiment, the position of the two substrates 400 and 400 is
adjusted, both substrates are bonded together with a pressure, and
the substrates 400 and 400 are bonded by surface activated bonding.
Alternatively, the conventionally well known wafer bonding may also
be applied instead of surface activated bonding. In the "wafer
bonding" process, two Si wafers are cleaned sufficiently to make
the surface hydrophilic and superimposed, and heat-treated at about
1,000.degree. C. to bond strongly. In this method, because impurity
distribution of the region formed by ion implantation is changed
due to re-diffusion as the result of the high temperature heat
treatment, and the impurity distribution change causes change of
the form of the micro-structure, it is necessary that the size of
the implantation mask pattern is corrected previously for the
change. Surface activated bonding by FAB is therefore preferable
because such correction is unnecessary.
[0160] Next, as shown in FIG. 25(e), the back side of the substrate
400 having the surface on which the p.sup.+ Si region 410a
corresponding to the cross-sectional form of the second layer is
formed is polished until the releasing layer 401 of SiO.sub.2 is
exposed. Because the releasing layer 401 can be detected when it is
exposed, it is avoided that the Si thin film 410 of the bonding
interface is undesirably polished excessively in the polishing
process.
[0161] Next, as shown in FIG. 25(f), the releasing layer 401 is
removed by etching with buffered hydrofluoric acid, and a
semi-finished product having two laminated Si thin films 410 is
completed.
[0162] Subsequently, the above-mentioned processes (d) through (f)
are repeated to form a semi-finished product having as many
laminated Si thin films 410 as required.
[0163] Next, as shown in FIG. 25(h), the Si thin film 410 around
the p.sup.+ Si region 410a is removed by etching with a KOH
solution or EDP (ethylenediamine pyrocatechol) solution in the
development process. The significant difference of the etching rate
between non-doped Si and doped Si to these solutions allows the
non-doped Si to be removed selectively. Though not shown in the
drawing, the back side of the substrate 400 may be protected with a
silicon nitride film, for example. Finally the releasing layer 401
on the substrate 400 is removed by etching with a buffered
hydrofluoric acid, then the completed micro-structure 4 is
separated from the substrate 400.
[0164] According to the fifth embodiment, there are the doped
micro-structure structural portion and the non-doped portion
surrounding the doped portion both having the same thickness, the
surrounding portion functions as a support, an assembled part which
has a complex form with an overhang can be therefore formed. The
ion-implanted region is formed as a latent image, and the latent
image is developed with an EDP solution after lamination,
alternatively the latent image forming method and development
method other than the above-mentioned methods such as selective
exposure of photo-resist and development treatment using a
developing solution may be used.
[0165] In this embodiment, a silicon nitride film 411 is used as
the implanting mask during the ion implanting process,
alternatively a silicon oxide film or photo-resist may be used.
EMBODIMENTS
[0166] Embodiments of the releasing layer to be formed on a
substrate surface are described hereinafter.
Embodiment 1
[0167] Because, by using fluoro polymer (CYTOP, product of Asahi
Glass Company) as the releasing layer, a thin layer can be formed
on a substrate by spin-coat method, and surface energy is very
small (generally very water repellent), the adhesion of the film
formed on the surface is very low (about 1 MPa), and the film is
suitable as the releasing layer. After spin-coating of a coupling
agent (to improve the adhesion on a substrate) on an Si wafer or
glass substrate, a film with thickness of about 2 .mu.m of fluoro
polymer (CYTOP) is spin-coated and baked at the maximum temperature
of 300.degree. C. to form a releasing layer.
Embodiment 2
[0168] By using fluorinated polyimide (OPI-N1005, product of
Hitachi Chemical Co., Ltd.) as the releasing layer a releasing
layer can be formed by spin-coat method, and polyimide has a glass
transition temperature higher than fluoro polymer (CYTOP), and the
maximum temperature of film deposition and patterning process is
higher. After coating of a coupling agent, a film with a thickness
of about 5 .mu.m of fluorinated polyimide (OPI-N1005) is
spin-coated on a substrate, and baked at the maximum temperature of
350.degree. C. to form a releasing layer.
Embodiment 3
[0169] It is confirmed that a fluorinated surface layer obtained by
exposing the substrate surface to a gas containing fluorine atom
exhibits the same effect. Specifically, an Si wafer, an Si wafer on
which oxide film is formed, or a glass substrate or these
substrates coated with non-fluorinated polyimide introduced into a
vacuum equipment (dry etching machine), and plasma treatment is
applied using CF.sub.4 gas (gas flow rate of 100 sccm, discharging
power of 500 W, pressure of 10 Pa, and time of 10 minutes), this
process results in reduced adhesion strength with the thin film.
The same process is also effective using SF.sub.6 gas.
[0170] As described hereinabove, according to the present
invention, because thin films are used as starting material, and a
plurality of thin films are laminated by bonding, thus the
dimensional precision is high and high resolution in the lamination
direction is realized.
[0171] Because a micro-structure composed of thin films consisting
of a metal or an insulator can be formed, it is possible to
manufacture micro-structures directly from a metal or an insulator
such as ceramics.
[0172] By applying a process in which the first thin film and
second thin film are formed with the same film thickness, a
plurality of thin films are laminated, and then the first thin film
or second thin film is removed selectively, a micro-structure
having a plurality of structural elements is formed simultaneously,
and thus the steps of the manufacturing and assembling work of
micro-structures are significantly reduced.
* * * * *