U.S. patent application number 09/779655 was filed with the patent office on 2002-08-15 for process method of using excimer laser for forming micro spherical and non-spherical polymeric structure array.
This patent application is currently assigned to Industrial Technology Research Institute. Invention is credited to Chen, Shih-Chou, Chou, Min-Chieh, Pan, Cheng-Tang, Tsai, Hung-Yin.
Application Number | 20020110766 09/779655 |
Document ID | / |
Family ID | 25117088 |
Filed Date | 2002-08-15 |
United States Patent
Application |
20020110766 |
Kind Code |
A1 |
Tsai, Hung-Yin ; et
al. |
August 15, 2002 |
Process method of using excimer laser for forming micro spherical
and non-spherical polymeric structure array
Abstract
A process method of using excimer laser for forming micro
spherical and non-spherical polymeric structure array includes a
photomask which has a selected curved pattern formed thereon. The
curved pattern has non-constant widths along a straight line
direction. An excimer laser beam source is deployed to project
through the photomask on a substrate coated with a polymeric
material while the substrate is moving in a direction normal to the
straight line direction for the polymeric material to receive laser
beam projection with different time period. The polymeric material
thus may be etched to different depth to form a three dimensional
pattern desired. By projecting and etching the polymeric material
two times at different directions or through different photomask
patterns, a sphere like or non-sphere like surface of micro array
structure may be obtained.
Inventors: |
Tsai, Hung-Yin; (Hsinchu,
TW) ; Pan, Cheng-Tang; (TaiNan, TW) ; Chou,
Min-Chieh; (Taipei, TW) ; Chen, Shih-Chou;
(Hsinchu, TW) |
Correspondence
Address: |
DOUGHERTY & TROXELL
SUITE 1404
5205 LEESBURG PIKE
FALLS CHURCH
VA
22041
US
|
Assignee: |
Industrial Technology Research
Institute
|
Family ID: |
25117088 |
Appl. No.: |
09/779655 |
Filed: |
February 9, 2001 |
Current U.S.
Class: |
430/397 ;
430/322; 430/323; 430/324; 430/394; 430/945 |
Current CPC
Class: |
G03F 1/50 20130101; G03F
7/0005 20130101; Y10S 430/146 20130101 |
Class at
Publication: |
430/397 ;
430/322; 430/323; 430/324; 430/394; 430/945 |
International
Class: |
G03F 007/20 |
Claims
What is claimed is:
1. A process method of using excimer laser for forming polymeric
structure array, comprising: a. preparing a substrate which has a
surface coated with a polymeric material, and setting up at least
one photomask which has a selected curved pattern formed thereon,
b. deploying an excimer laser beam source to project through the
photomask on the polymeric material and moving the substrate along
a first corresponding direction for forming a first three
dimensional pattern on the polymeric material, and c. moving the
substrate along a second corresponding direction and projecting the
laser beam source through the photomask on the first three
dimensional pattern to form an etched second three dimensional
pattern thereon.
2. The process method of claim 1, wherein the polymeric material is
a photoresist material.
3. The process method of claim 1, wherein the polymeric material is
coated on the substrate by means of a process selected from the
group consisting of rotary spindle, printing, and chemical
deposition.
4. The process method of claim 1, wherein the substrate is a
semiconductor substrate.
5. The process method of claim 1, wherein the curved pattern
includes a plurality of transparent geometric zones along a
direction normal to the corresponding direction.
6. The process method of claim 5, wherein the transparent geometric
zones along the direction normal to the corresponding direction
have non-constant widths such that the laser beam source projects
through the photomask on the polymeric material when the substrate
is moving, the polymeric material receives laser beam source
projection with different time period in a direction normal to the
corresponding direction to form different degree of etching for
forming the three dimensional pattern.
7. The process method of claim 1, wherein the first corresponding
direction is normal to the second corresponding direction.
8. The process method of claim 7, wherein the substrate is turned
ninety degree after the step (b) for the laser beam source
projecting along the first corresponding direction at the step (c)
so that the first corresponding direction be normal to the second
corresponding direction.
9. The process method of claim 1, wherein the curved pattern is
same for the step (b) and (c).
10. The process method of claim 1, wherein the curved pattern at
the step (b) is different from that at the step (c).
11. The process method of claim 10, wherein the first corresponding
direction is same as the second corresponding direction.
12. The process method of claim 1, wherein the second three
dimensional pattern is sphere-like structure.
13. The process method of claim 1, wherein the step (c) is followed
by the following step: d. clearing polymeric material debris by
means of chemical etching process.
14. The process method of claim 1, wherein the step (c) is followed
by the following step: e. performing surface smoothing process on
second three dimensional pattern surface.
15. The process method of claim 14, wherein the surface smoothing
process is choosing from a group consisting of: high energy beam
rapid process, rapid tempering annealing process, and reflow
diffusion process done at a temperature lower than the melting
point of the polymeric material.
16. The process method of claim 1, wherein the step (c) is followed
by the following steps: f. spray plating a seed layer on the
substrate and second three dimensional pattern, g. electroplating a
metal layer to a selected thickness on the seed layer, and h.
separating the metal layer from the substrate and second three
dimensional pattern for forming a metal mold for pressing micro
array structure.
17. A process method of using excimer laser for forming micro
spherical and non-spherical polymeric structure array, comprising:
a. preparing a substrate which has a surface coated with a
polymeric material, and setting up at least one photomask which has
a selected curved pattern formed thereon, the curved pattern having
a plurality of transparent zones in selected geographic forms along
a straight line direction, the transparent zones having
non-constant widths along the straight line direction, and b.
deploying an excimer laser beam source to project through the
photomask on the polymeric material and moving the substrate along
a first corresponding direction for forming a first three
dimensional pattern on the polymeric material.
18. The process method of claim 17, wherein the step (b) is
followed by the following step: c. the substrate is turned ninety
degree and moved along the first corresponding direction for the
laser beam source to projecting through the photomask on the first
three dimensional pattern to form a second three dimensional
pattern by etching.
19. The process method of claim 17, wherein the curved pattern on
the photomask used in the step (b) is different from that in the
step (c).
20. The process method of claim 17, wherein the step (b) is
followed by the following steps: d. clearing polymeric material
debris by means of chemical etching process; e. performing surface
smoothing process on the three dimensional pattern surface.
21. The process method of claim 20, wherein the surface smoothing
process is choosing from a group consisting of: reflow diffusionv
process done at a temperature lower than the melting point of the
polymeric material, high energy beam rapid process, and rapid
tempering annealing process.
22. The process method of claim 17, wherein the step (b) is
followed by the following steps: f. spray plating a seed layer on
the substrate and second three dimensional pattern, g.
electroplating a metal layer to a selected thickness on the seed
layer, and h. separating the metal layer from the substrate and
second three dimensional pattern for forming a metal mold for
pressing micro array structure.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a process method of using excimer
laser for forming micro spherical and non-spherical polymeric
structure array and particularly a excimer laser process to form a
micro spherical array structure on a substrate for producing a
metal mold to fabricate liquid crystal display (LCD) face plate or
photosensitive face plate.
[0003] 2. Description of the Prior Art
[0004] In order to increase visibility angle of LCD screen or other
photosensitive plate, the face plate of these devices generally has
to form a plurality of bulged micro spherical array structure to
enhance light condensing (or dispersing) property. This micro
spherical array structure usually is made by means of pressing of a
metal mold. The metal mold (pressing mold) is formed by spray
plating a metal layer on a main mold, then peeling off the metal
layer from the main mold.
[0005] Conventionally, fabricating the main mold include the
following methods:
[0006] 1. Using Single Stepper Exposure and High Temperature Reflow
Process:
[0007] As shown in FIGS. 1A through 1D, this process firstly
prepares a substrate 11 coated with a photoresist layer 12 (FIG.
1A). Then using a stepper 14 to proceed single stepping exposure by
zones on the substrate 11 through a photomask 13 (FIG. 1B).
Afterward, the non-exposure portion of the photoresist 12 is
cleared through chemical agents and resulting in a micro-struts
photoresist 15 array structure (FIG. 1C). Thereafter, using high
temperature reflow process to heat the substrate around or
exceeding the photoresist melting temperature to melt the surface
of the micro-struts photoresist 15 for forming a curve shaped
surface 16 (FIG. 1D).
[0008] This method has the following disadvantages: 1. It needs
high temperature reflow process. The process is time consuming and
highly unstable. It is difficult to precisely control the spherical
surface formation. 2. Stepping exposure process can only produce
two dimensional (2D) strut structure, but not spherical or
non-spherical three dimensional (3D) curved surfaces.
[0009] 2. Multiple Stepping Exposure Micro Photo Process.
[0010] In the multiple stepping exposure micro process, the step 1B
and 1C set forth above are repeatedly performed with different
photomasks to gradually expand the exposure area of the photoresist
until a pyramid-shaped photoresist structure is formed. Then the
high temperature reflow process is proceeded. The reflow process
may be done at a lower temperature and shorter time period. The
spherical surface is also easier to control. However it has more
and complicated process steps. It takes more process time and costs
higher. To clean the photoresist needs a lot of chemicals and may
result in severe environmental pollution problem.
[0011] 3. Photosensitive Glass Process:
[0012] As shown in FIGS. 2A and 2B, this process firstly uses an
ultraviolet light source 24 (UV) to perform stepping exposure on a
photosensitive glass 21 through a photomask 23 (FIG. 2A). The
photosensitive glass 21 is coated with a different type of
photosensitive material 22 which will be hardened and expanded upon
the projection of ultraviolet light. The non-exposure portion of
the photosensitive material will be squeezed and to form a bulged
structure 25 (FIG. 2B).
[0013] However this process also has disadvantages. For instance,
the photosensitive glass is very expensive and difficult to
procure. The bulged structure is also difficult to control
accurately.
[0014] 4. Heated Dripping Process:
[0015] As shown in FIG. 3, this process forms the bulged 3D
structure 33 by means of dripping heated photoresist 32 one by one
(or multiple drops at a time) on the substrate 31. Th drawback of
this process is that it totally cannot control the micro spherical
array structure formation.
[0016] All the conventional techniques set forth have their share
of shortcomings. There is still room for improvement.
SUMMARY OF THE INVENTION
[0017] It is therefore an object of this invention to provide a
process method of using excimer laser for forming spherical and
non-spherical polymeric structure array that may precisely form
micro spherical or non-spherical surface array structure on a
substrate in a simpler and lower cost way.
[0018] It is another object of this invention to provide a process
method of using excimer laser for forming spherical and
non-spherical polymeric structure array that uses a photomask which
has a selected curved pattern to receive excimer laser beam
projection upon a polymeric material coated on a substrate. The
curved pattern has different width along a straight line. The
excimer laser beam hits the polymeric material and peels the
material to create etching effect. During the laser beam projection
and etching process, the substrate may be moved normally against
the straight line direction so that the polymeric material may
receive projection of different time period along the straight line
direction to obtain different depth of etching for forming the 3D
pattern desired.
[0019] For achieving aforesaid objects, the process of this
invention includes the follow steps:
[0020] a. preparing a substrate which has a surface coating with a
polymeric material and at least one photomask having a selected
curved pattern formed thereon,
[0021] b. using a excimer laser beam source to project through the
photomask on the polymeric material on the substrate and moving the
substrate along a first corresponding direction for etching and
forming a first 3D pattern on the polymeric material,
[0022] c. moving the substrate along a second corresponding
direction and projecting the excimer laser beam through the
photomask on the first 3D pattern to form a second 3D pattern in
spherical-like manner.
[0023] In another aspect, this invention may further include the
following steps:
[0024] d. using chemical etching method to remove debris of the
polymeric material,
[0025] e. performing surface process to smooth the surface of the
second 3D pattern,
[0026] f. spray plating a seed layer on the substrate and second 3D
pattern,
[0027] g. electroplating the spray plated seed layer to form a
metal layer to a selected thickness,
[0028] h. separating the metal layer from the substrate and second
3D pattern to make the metal layer become a metal mold for pressing
a micro array structure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The invention, as well as its many advantages, may be
further understood by the following detailed description and
drawings, in which:
[0030] FIGS. 1A-1D are schematic views of process steps of a
conventional single stepper exposure and-high temperature reflow
process.
[0031] FIGS. 2A and 2B are schematic views of process steps of a
conventional photosensitive glass process.
[0032] FIG. 3 is schematic view of the process of a conventional
heated dripping process.
[0033] FIGS. 4A-4G are schematic views of the process steps of an
embodiment of this invention for forming micro spherical and
non-spherical surface in polymeric structure array.
[0034] FIG. 5A is a front view of a selected curved pattern on a
photomask for this invention.
[0035] FIG. 5B is a perspective view of a first 3D pattern formed
by means of the photomask shown in FIG. 5A.
[0036] FIG. 6A is a front view of another selected curved pattern
on a photomask for this invention.
[0037] FIG. 6B is a perspective view of a first 3D pattern formed
by means of the photomask shown in FIG. 6A.
[0038] FIG. 7 is a schematic perspective view of a spherical micro
array structure, after the polymeric material subjects to photo
etching for two times.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0039] This invention aims at providing a process method of using
excimer laser for forming spherical and non-spherical polymeric
structure array. The process employs a photomask which has a
selected curved pattern formed thereon. The curved pattern has
various width along a straight line direction. When an excimer
laser beam projects through the photomask on a substrate coated
with a polymeric material, the polymeric material will be peeled
off to produce etching result. During the projection and etching
process, the substrate is moved along a normal direction against
the straight line direction for the polymeric material to receive
laser beam projection of different time period along the straight
line direction. Then the polymeric material will be etched to
different depth to form a 3D pattern desired.
[0040] FIGS. 4A through 4G show a preferred embodiment of this
invention. It includes the following steps:
[0041] a. Preparing a substrate 41 which has a surface coating with
a polymeric material 42 and preparing at least one photomask 44
which has a selected curved pattern formed thereon (FIG. 4A). The
polymeric material 42 is preferably selected from the group which
has relatively lower key link energy, such as photoresist material,
so that the key link may be broken down by laser beam projection
for etching purpose. The polymeric material 42 may be coated on the
substrate 41 by means of rotary spindle, printing, chemical
deposition and the like. The substrate 41 is preferably made from
material which may resist excimer laser etching and may become a
stop layer of etching, such as silicon.
[0042] The curved pattern has a plurality of transparent zones in
geometric forms along a straight line direction. The transparent
zones have different widths along the straight line direction.
[0043] b. Using an excimer laser beam source 45 to projecting the
laser beam through the photomask 44 to the polymeric material 42 on
the substrate 41, in the mean time (during laser beam projection)
moving the substrate 41 along a first corresponding direction to
form an etching first 3D pattern on the polymeric material 43 (FIG.
4B). This process is different from conventional stepping exposure
process using a stepper.
[0044] The first corresponding direction is normal to the straight
line. Hence when the excimer laser beam source 45 projects the
moving substrate 41 through the photomask 44, the polymeric
material 42 receives laser beam projection with different time
period along the straight line direction, and may result in
different degree of etching for forming the first 3D pattern
43.
[0045] c. When necessary (depending on the finishing 3D pattern
desired), the excimer laser beam source 45 may be deployed to
project the first 3D pattern through the photomask 45 again while
moving the substrate 41 along a second corresponding direction to
form a second 3D pattern. In a preferred embodiment of this
invention, the second corresponding direction is normal to the
first corresponding direction. The curved pattern on the photomask
44 used at the step b and c may be the same or different.
[0046] In another embodiment of this invention, the second
corresponding direction at the step c may be taken by turning the
substrate 41 ninety degree after the step b, then performing the
step c process along the first corresponding direction. It may also
produce the second 3D pattern with same result as the relative
moving corresponding direction in the step c and b is also normal
against each other.
[0047] In yet another embodiment, multiple laser beam projections
may be done if projection by two times is not adequate. The
relative moving corresponding direction between the photomask 44
and substrate 41 may be the same or different for every laser beam
projection, or the photomask 44 of different curved pattern may be
used (in such a case, the moving corresponding direction may be the
same) until a desired 3D pattern is obtained.
[0048] d. Clearing the polymeric material debris by means of a
chemical etching process as shown in FIG. 4C. As the etching
process through the excimer laser beam projection might produce
some peeled off debris of polymeric material scattering on the
substrate 41 or 3D pattern 43, these debris may be cleared and
removed rapidly be means of the chemical etching process.
[0049] e. Smoothing the surface 46 of the 3D pattern 43 (the first
or second 3D pattern) (FIG. 4D). As the second 3D pattern is
already sphere-like, this step may be done by means of a low
temperature process to melt a small amount of the surface for
producing the smooth surface desired. For instance, by performing
low temperature reflow diffusion at a temperature lower than the
melting point (Tg) of the polymeric material, rapid processing
using high energy beam, or rapid tempering annealing (RTA) and the
like.
[0050] f. Spray plating metallic material on the substrate 41 and
3D pattern to form a seed layer 47 (FIG. 4E). The seed layer
material is preferably nickel or its alloy.
[0051] g. Electroplating a metallic material on the seed layer 47
to a selected thickness to form a metal layer 48 (FIG. 4F). The
metal layer 48 is preferably nickel or its alloy.
[0052] h. Separating the metal layer 48 from the substrate 41 and
second 3D pattern to become an independent component (FIG. 4G). The
separated metal layer 48 then may be used as the mold for producing
the micro array structure desired.
[0053] FIGS. 5A and 5B show respectively an embodiment of a curved
pattern on the photomask and a first 3D pattern which might be
formed therewith. The photomask 51 has a plurality of semicircle
transparent zones 52 in the straight line direction 91. The width
of the transparent zones 52 in the straight line direction 91 is
not a constant value (FIG. 5A). When the substrate 61 is moved
along a first corresponding direction 92 (normal to the straight
line direction 91) for receiving laser beam projection and etching,
the polymeric material on the substrate 61 receives projection of
different time period and forms a first 3D pattern 62 which
consists of a plurality of semicircle concave troughs (FIG.
5B).
[0054] FIGS. 6A and 6B show respectively another embodiment of a
curved pattern on the photomask 51a and a first 3D pattern which
might be formed therewith. By means of similar processes shown in
FIGS. 5A and 5B, the photomask 51a has a selected pattern which
includes transparent zones 52a for forming a first 3D pattern 62a
of protrusive semi cylindrical structure on the substrate 61a. When
the substrate 61a is turned ninety degree and be etched one more
time using the photomask 51a, a second 3D pattern 63 as shown in
FIG. 7 may be obtained which nearly becomes semispherical
structure.
[0055] Of course, besides the semispherical 3D pattern structure,
this invention may be used to produce other types of 3D pattern
structure such as ellipsoidal surface, corrugated surface and the
like. It may be done by using different curved pattern desired on
the photomask and projecting laser beam by different times or
moving at different corresponding directions.
[0056] In summary, this invention offers the following advantages
over conventional techniques:
[0057] 1. Using excimer laser beam source to project through the
photomask to perform process may easily and accurately form
sphere-like micro structure. Then using a low temperature reflow
diffusion process may obtain a smooth surface desired.
[0058] 2. Resolving the problem incurred in conventional technique
which needs high temperature reflow process after forming circle
strut structure through the single step micro photo process.
[0059] 3. Comparing with complex and lengthy process of
conventional multiple steps micro photo process for forming pyramid
type structure, this invention has simpler process and shorter
process time.
[0060] 4. This invention may have different process parameters for
forming different types of non-spherical micro structure, such as
changing the pattern on the photomask, changing moving
corresponding direction during laser beam projection process.
[0061] 5. This invention may accurately produce sphere or
non-sphere surface micro structure. Process control is much more
easier and precise than conventional technique which uses bulging
or heated dripping process.
[0062] 6. This invention is lower cost than conventional technique
that uses photosensitive glass.
[0063] It may thus be seen that the objects of the present
invention set forth herein, as well as those made apparent from the
foregoing description, are efficiently attained. While the
preferred embodiments of the invention have been set forth for
purpose of disclosure, it would be obvious to those skilled in the
art that various other changes and modifications can be made
without departing from the spirit and scope of this invention.
* * * * *