U.S. patent application number 10/956418 was filed with the patent office on 2005-03-17 for manufacturing method for microdisplay.
Invention is credited to Chen, Sheng-Lung, Kuan, Da-Shuang.
Application Number | 20050057718 10/956418 |
Document ID | / |
Family ID | 32986195 |
Filed Date | 2005-03-17 |
United States Patent
Application |
20050057718 |
Kind Code |
A1 |
Chen, Sheng-Lung ; et
al. |
March 17, 2005 |
Manufacturing method for microdisplay
Abstract
The present invention provides a manufacturing method for a
microdisplay. After providing a wafer with a plurality of pixel
structures on the front side, trenches with a pattern are formed on
the backside of the wafer. A transparent plate is disposed above
the front side of the wafer and a sealant is applied to join the
wafer and the transparent plate. After cutting the wafer and the
transparent plate into display cells of suitable sizes, liquid
crystal is then introduced in-between the sealant of the display
cells.
Inventors: |
Chen, Sheng-Lung; (Hsinchu,
TW) ; Kuan, Da-Shuang; (Hsinchu Hsien, TW) |
Correspondence
Address: |
J C PATENTS, INC.
4 VENTURE, SUITE 250
IRVINE
CA
92618
US
|
Family ID: |
32986195 |
Appl. No.: |
10/956418 |
Filed: |
October 1, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10956418 |
Oct 1, 2004 |
|
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10410807 |
Apr 9, 2003 |
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Current U.S.
Class: |
349/158 |
Current CPC
Class: |
G02F 1/136277 20130101;
G02F 1/1341 20130101 |
Class at
Publication: |
349/158 |
International
Class: |
G02F 001/1333 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 24, 2003 |
TW |
92106446 |
Claims
1-7. (canceled)
8. A method for improving uniformity of a microdisplay, comprising:
providing a first substrate, wherein a front side of the first
substrate has a plurality of pixel structures; forming trenches
with a pattern on a backside of the first substrate; forming a
sealant pattern on the front side of the first substrate; and
disposing a second substrate above the front side of the first
substrate, so that the first substrate is adhered to the second
substrate.
9. The method of claim 8, wherein the method of forming trenches
with a pattern includes performing laser cutting.
10. The method of claim 8, wherein the pattern is a checker
pattern.
11. The method of claim 8, wherein the trenches have a width of
about 50-150 microns.
12. The method of claim 8, wherein the trenches have a depth of
about 50-300 microns.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the priority benefit of Taiwan
application serial no. 92106446, filed Mar. 24, 2003.
BACKGROUND OF THE INVENTION
[0002] 1. Field of Invention
[0003] The present invention relates to a manufacturing method of a
microdisplay. More particularly, the present invention relates to a
manufacturing method for improving the non-uniformity of the
microdisplay.
[0004] 2. Description of Related Art
[0005] Liquid crystal pixel structure has been widely applied in
daily life applications, including liquid crystal televisions,
liquid crystal monitors of portable computers or desktop personal
computers and liquid crystal projectors. For large-scale displays,
the liquid crystal projectors are particularly important. The core
element of the liquid crystal projector is the optical engine that
generally includes a light source, an optical component consisting
of prism pairs and several liquid crystal panels (LCPs)
corresponding to different optical paths (R, G, B). The liquid
crystal panels, being one type of microdisplays, have pixels of
small sizes. Because of the small-sized pixels in the liquid
crystal panels, liquid crystal on silicon (LCOS) technology is
commonly employed to fabricate the liquid crystal panels.
[0006] The LCOS liquid crystal panel is in fact a silicon wafer
back panel, by using MOS transistors in place of the thin film
transistors used in the conventional liquid crystal displays
(LCDs). Since the pixel electrodes of the LCOS liquid crystal panel
are made of metal materials, the LCOS liquid crystal panel is a
reflective type liquid crystal panel. Moreover, because the metal
pixel electrodes completely cover the pixel region, especially the
MOS transistors, the LCOS liquid crystal panel is superior in image
display compared with conventional LCDs. Hence, the LCOS liquid
crystal panels are dominantly used in the liquid crystal
projectors.
[0007] FIG. 1 is a display view of the structure for the prior art
microdisplay under assembly. As shown in FIG. 1, the conventional
microdisplay usually includes a silicon wafer substrate 100 with a
pixel structure 104 on the front side and a glass plate 102
disposed opposite to the front side of the silicon wafer 100.
[0008] FIG. 2 is a cross-sectional view of the prior art
microdisplay structure in FIG. 1 after assembly. As shown in FIG.
2, a sealant 106 is usually used to glue the silicon wafer
substrate 100 together with the glass plate 102. After cutting the
glued glass plate 102 and the silicon wafer substrate 100 into
display cells of suitable sizes, liquid crystal is then filled into
the space (gap) between the silicon wafer substrate 100 and the
glass plate 102.
[0009] However, because of the high temperature in the thermal
processes and the formation of layers in different materials on the
silicon wafer substrate 100, the stress acting on the silicon wafer
substrate 100 often leads to distortion or warp in the silicon
wafer substrate 100. Once the silicon wafer substrate 100 is
distorted, bent or even arched, the central gap 110 of the display
cell will be larger than the edge gap 112. Such non-uniformity,
resulting from uneven gaps between the silicon wafer substrate 100
and the glass plate 102 in different locations, gives rise to
inconsistency in projected images.
[0010] Although spacers are implemented in the conventional LCDs to
lessen variation of gaps, application of spacers in microdisplays,
especially microdisplays of liquid crystal projectors, had better
be avoided so as to increase the quality of images.
SUMMARY OF THE INVENTION
[0011] The present invention provides a manufacturing method of a
microdisplay for preventing the non-uniformity of gaps between the
silicon wafer and the glass.
[0012] The present invention provides a manufacturing method of a
microdisplay for improving the inconsistency of the projection
(projected images).
[0013] The present invention provides a manufacturing method of a
microdisplay, which greatly improves planarity of the wafer.
[0014] As embodied and broadly described herein, the present
invention provides a manufacturing method for a microdisplay, which
can reduce stress of the wafer substrate and help keep planarity of
the wafer substrate. Before the assembly of the wafer substrate and
the plate, the backside of the wafer substrate is cut to form a
trench pattern, so that the stress of the wafer substrate is
reduced. Consequently, even and uniform gaps are formed between the
wafer substrate and the transparent plate in different locations
after fitting the wafer substrate and the plate together. Such
uniformity of gaps between the wafer substrate and the glass plate
results in high-quality and undeviating images.
[0015] It is to be understood that both the foregoing general
description and the following detailed description are exemplary,
and are intended to provide further explanation of the invention as
claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The accompanying drawings are included to provide a further
understanding of the invention, and are incorporated in and
constitute a part of this specification. The drawings illustrate
embodiments of the invention and, together with the description,
serve to explain the principles of the invention. In the
drawings,
[0017] FIG. 1 is a display view of the prior art microdisplay
structure under assembly;
[0018] FIG. 2 is a cross-sectional view of the prior art
microdisplay structure in FIG. 1 after assembly;
[0019] FIG. 3A is a three-dimensional view of the wafer substrate
for a microdisplay after cutting according to one preferred
embodiment of the present invention;
[0020] FIG. 3B is a cross-sectional view of the wafer substrate for
a microdisplay after cutting according to one preferred embodiment
of the present invention;
[0021] FIG. 4 is a display view for the wafer substrate and the
transparent plate of the microdisplay under assembly according to
one preferred embodiment of the present invention;
[0022] FIG. 5 is a cross-sectional view for the wafer substrate and
the transparent plate of the microdisplay after assembly according
to one preferred embodiment of the present invention;
[0023] FIG. 6 is a cross-sectional display view of a microdisplay
after cutting according to one preferred embodiment of the present
invention; and
[0024] FIG. 7 is a flow chart showing the process steps for
improving unifomity of the microdisplay according to another
preferred embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0025] First Embodiment
[0026] FIG. 3A is a three-dimensional view of a wafer substrate for
a microdisplay after cutting according to the first preferred
embodiment of the present invention, while FIG. 3B is a
cross-sectional view of the wafer substrate of FIG. 3A. Referring
to FIGS. 3A and 3B, a wafer substrate 300 is provided, while a
plurality of pixel structures 304 (shown in FIG. 4) are formed on
the front side 320 of the wafer substrate 300. For example, the
wafer substrate 300 is a silicon wafer substrate. The backside 322
of the wafer substrate 300 is cut or sectioned in order to form
trenches 323 with a pattern 324. The trenches are formed in a grid
pattern or a checker pattern, or in other arranged patterns. As
shown in an enlarged view (left side) for a portion of the wafer
substrate in FIG. 3B, the trenches 323 of the grid pattern 324 have
a width AA of about 50-150 microns and a depth BB of about 50-300
microns. For example, laser cutting is used to perform the cutting
of the wafer substrate (to form trenches in a pattern).
[0027] FIG. 4 is a display view for the wafer substrate and the
transparent plate of the microdisplay under assembly according to
the first preferred embodiment of the present invention. A
transparent plate 302 is disposed above the front side 320 of the
wafer substrate 300. The transparent plate 302 is, for example, a
glass plate.
[0028] FIG. 5 is a cross-sectional view for the wafer substrate and
the transparent plate of the microdisplay after assembly according
to the first preferred embodiment of the present invention. A
sealant 306 is applied between the front side 320 of the wafer
substrate 300 and the transparent plate 302, so that the wafer
substrate 300 is adhered to the transparent plate 302. Liquid
crystal 314 is introduced (injected) in-between the wafer substrate
300, the transparent plate 302 and the sealant 306.
[0029] FIG. 6 is a cross-sectional display view of a microdisplay
after cutting according to the first preferred embodiment of the
present invention. As shown in FIG. 6, the wafer substrate 300 and
the transparent plate 302 are cut into display cells 600 of a
suitable size and a liquid crystal layer 314 is then applied into
the display cell 600.
[0030] Since the backside 322 of the wafer substrate 300 is
sectioned to form trenches 323 with a pattern 324, the stress
resulting from the oxide film (not shown) on the backside 322 of
the wafer substrate 300 can be reduced. Hence, no distortion or
warp occurs to the wafer substrate 300, even after the wafer
substrate 300 is adhered to the transparent plate 302. The present
invention provides even and uniform gaps in different locations.
Taking the central gap 310 and the edge gap 312 as an example, no
great difference is found among these two gaps.
[0031] Second Embodiment
[0032] FIG. 7 is a flow chart showing the process steps for
improving uniformity of the microdisplay according to the second
preferred embodiment of the present invention. In step 700, a first
substrate is provided with a plurality of pixel structures formed
on the front side of the first substrate. In step 702, the backside
of the first substrate is sectioned (cut) to form trenches with a
pattern. The trenches are formed in a grid pattern or a checker
pattern, or in other arranged patterns by, for example, laser
cutting, while the trenches have a width of about 50-150 microns
and a depth of about 50-300 microns.
[0033] In step 704, a sealant pattern is formed on the front side
of the first substrate. In step 706, a second substrate is arranged
above the front side of the first substrate, so that the first
substrate is adhered to the second substrate.
[0034] In conclusion, the present invention has the following
advantages:
[0035] Since the backside of the wafer substrate is sectioned to
form trenches with a pattern, the stress can be reduced.
[0036] Because the wafer substrate is cut with the pattern, the
wafer can keep planarity even after the wafer substrate is adhered
to the transparent plate, thus providing even and uniform gaps in
different locations between the wafer substrate and the transparent
plate.
[0037] It will be apparent to those skilled in the art that various
modifications and variations can be made to the structure of the
present invention without departing from the scope or spirit of the
invention. In view of the foregoing, it is intended that the
present invention cover modifications and variations of this
invention provided they fall within the scope of the following
claims and their equivalents.
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