U.S. patent application number 09/871122 was filed with the patent office on 2002-04-18 for liquid crystal display device and method of producing the same.
Invention is credited to Sato, Takusei, Wada, Tomohiro.
Application Number | 20020044237 09/871122 |
Document ID | / |
Family ID | 18666633 |
Filed Date | 2002-04-18 |
United States Patent
Application |
20020044237 |
Kind Code |
A1 |
Wada, Tomohiro ; et
al. |
April 18, 2002 |
LIQUID CRYSTAL DISPLAY DEVICE AND METHOD OF PRODUCING THE SAME
Abstract
A TFT substrate is provided near its outer periphery with a
metallic wiring and pad portions, and a conductive light-shielding
film is provided on the outside of these. The conductive
light-shielding film is left annularly along the outer peripheral
portion of the TFT substrate so that, when an upper layer
light-shielding film is formed on the TFT substrate, the upper
layer light-shielding film on the scribed line side would not
easily be exfoliated at the time of etching or cleaning. Of the
conductive light-shielding film, the position of the conductive
light-shielding film disposed on the outside of the pad portions is
shifted to the outer side so that the spacing between the
conductive light-shielding film and the pad portions is set to be,
for example, not less than 10 .mu.m. By this, electrostatic trouble
between the conductive light-shielding film and the pad portions is
restrained.
Inventors: |
Wada, Tomohiro; (Kagoshima,
JP) ; Sato, Takusei; (Tokyo, JP) |
Correspondence
Address: |
SONNENSCHEIN NATH & ROSENTHAL
P.O. BOX 061080
WACKER DRIVE STATION
CHICAGO
IL
60606-1080
US
|
Family ID: |
18666633 |
Appl. No.: |
09/871122 |
Filed: |
May 31, 2001 |
Current U.S.
Class: |
349/110 ;
349/149 |
Current CPC
Class: |
G02F 1/133351 20130101;
G02F 1/13454 20130101; G02F 1/136204 20130101; G02F 1/133512
20130101 |
Class at
Publication: |
349/110 ;
349/149 |
International
Class: |
G02F 001/1333; G02F
001/1345 |
Foreign Application Data
Date |
Code |
Application Number |
May 31, 2000 |
JP |
P2000-162775 |
Claims
What is claimed is:
1. A liquid crystal display device comprising one of a plurality of
driving substrates formed en bloc on a substrate and produced
individually by splitting said substrate along scribed lines, said
liquid crystal display device comprising: a conductive
light-shielding film formed annularly along a peripheral portion of
said driving substrate, and a plurality of pad portions arranged on
the inside of said conductive light-shielding film along one side
of said driving substrate, wherein the spacing between said
conductive light-shielding film and each said pad at the side of
said driving substrate where said pad portions are provided is at
least 10 .mu.m.
2. A liquid crystal display device as set forth in claim 1, wherein
said conductive light-shielding film is formed by use of a
combination of W, Mo, Ta, Cr, Ti, Al, Cu, Zn, silicides of these
elements and alloys of these elements.
3. A liquid crystal display device as set forth in claim 1, wherein
said conductive light-shielding film has a thickness of 50 to 500
nm.
4. A liquid crystal display device as set forth in claim 1, wherein
said conductive light-shielding film has a low resistance of not
more than 200 K.OMEGA./.quadrature..
5. A liquid crystal display device as set forth in claim 1, wherein
said conductive light-shielding film has a transmittance to at
least light in the range of 400 to 500 nm of not more than 10%.
6. A method of producing a liquid crystal display device comprising
one of a plurality of driving substrates formed en bloc on a
substrate and produced individually by splitting said substrate
along scribed lines, said method comprising: a step of forming a
conductive light-shielding film annularly along a peripheral
portion of said driving substrate, and a step of forming a
plurality of pad portions arranged on the inside of said conductive
light-shielding film along one side of said driving substrate,
wherein the spacing between said conductive light-shielding film
and each said pad at the side of said driving substrate where said
pad portions are provided is at least 10 .mu.m.
7. A method of producing a liquid crystal display device as set
forth in claim 6, wherein said conductive light-shielding film is
formed at the same time when a wiring for pixel transistors or a
peripheral driving circuit is formed or when a light-shielding thin
film is same time when said wiring or said light-shielding thin
film is patterned.
8. A method of producing a liquid crystal display device as set
forth in claim 6, wherein said conductive light-shielding film is
present on said substrate only when said substrate is processed,
and is removed when said driving substrates are split.
Description
RELATED APPLICATION DATA
[0001] The present application claims priority to Japanese
Application No. P2000-162775 filed May 31, 2000, which application
is incorporated herein by reference to the extent permitted by
law.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a liquid crystal display
device for use as various display devices and a method of producing
the same.
[0003] Hitherto, there has been known a system in which a
multiplicity of driving substrates (TFT substrates) with pixel
transistors mounted thereon for constituting a liquid crystal
display device are formed en bloc on a substrate (wafer) and
individual TFT substrates are obtained by splitting the substrate
along scribed lines.
[0004] FIG. 3 is a plan view showing an example of a wiring pattern
on such a conventional TFT substrate, and FIG. 4 is a partly
sectional view showing an internal laminated structure in the
region of line A-A of FIG. 3.
[0005] As shown in FIG. 3, the region for forming one TFT substrate
10 is demarcated by scribed lines 2 formed in a grating form on a
wafer 1, and each TFT substrate 10 is provided with a display
region 12 in which pixel transistors 11 are disposed in a matrix
form.
[0006] On the outside of the display region 12, there are provided
a vertical driving circuit 13 and a horizontal driving circuit 14
for driving each pixel transistor in the display region 12, and,
further, on the outside thereof, there are provided a metallic
wiring 15 and a plurality of pad portions 16.
[0007] The pad portions 16 are arranged in parallel with and along
one side of the display region 12 where the horizontal driving
circuit 14 is disposed. These pad portions 16 are connected to the
metallic wiring 15, and are brought into contact with terminals of
an inspection apparatus or the like. Some of the pad portions 16
are provided as dummies which are not connected to the metallic
wiring 15.
[0008] Common electrode portions 15A are provided at corner
portions of the metallic wiring 15, for supplying electric power to
each of the driving circuits 13, 14 and the like.
[0009] In FIG. 4, a polycrystalline silicon film 22 is provided on
an interlayer insulation film 21 provided on a quartz substrate 20,
and an Al electrode film 23 and an upper layer light-shielding film
24 are provided thereon. A transparent electrode 26 is provided on
the upper side of the upper layer light-shielding film 24, with an
interlayer insulation film 25 therebetween.
[0010] Interlayer insulation films 27 and 28 are provided at an
outer peripheral portion of the polycrystalline silicon film 22,
and have an upwardly projected form, thereby forming the groove of
the scribed lines.
[0011] The upper layer light-shielding film 24 is a conductive
light-shielding film formed, for example, of an alloy of Al, Ti or
the like. The transparent electrode 26 is constituted of an ITO
film or the like, and the interlayer insulation film 25 is
constituted of a P-type TEOS film, a SOG (spin on glass) film or
the like. The other interlayer insulation films are constituted by
appropriately using a silicon oxide film, a silicon nitride film or
the like.
[0012] In the production of such a TFT substrate, in order to
alleviate warpage of the wafer due to stress, each thin film formed
on the scribed lines is removed by dry or wet etching and
lithography upon each formation of the thin film.
[0013] Therefore, the groove of the scribed lines is deepened at
the stage of forming the upper-layer light-shielding layer 24, the
upper-layer light-shielding layer 24 is left at bottom portions of
the scribed lines at the time of processing the upper-layer
light-shielding layer 24, and the left portions are exfoliated in
cleaning after the processing or the like, leading, for example, to
inter-pixel shortcircuit.
[0014] In consideration of this problem, as shown in FIG. 4, a
structure has been adopted in which the upper-layer light-shielding
film is left annularly along the outer peripheral portion of the
TFT substrate so that the upper-layer light-shielding film would
not easily be exfoliated.
[0015] However, where the upper-layer light-shielding film is left
annularly along the outer peripheral portion of the TFT substrate,
as shown in FIG. 5, the upper-layer light-shielding film 24 (shown
by solid line 24A in FIG. 5) is disposed also in the vicinity of
the above-mentioned pad portions 16, and the presence of such
annular upper-layer light shielding film 24 results in that damage
due to static electricity is liable to occur in a liquid crystal
step.
[0016] As a countermeasure against this problem, the annular
upper-layer light-shielding film may be formed at a position away
from the pad portions, to thereby prevent the bad influence of
static electricity. However, since various registration marks and
TEG are disposed on the scribed lines, formation of the annular
upper-layer light-shielding film at positions away from the center
of the TFT substrate along the entire periphery of the TFT
substrate results in that it is necessary to widen the scribed
lines for providing a layout space. In addition, chip size is
enlarged, and, hence, yield from the TFT substrates is reduced.
SUMMARY OF THE INVENTION
[0017] In consideration of the above-mentioned situations of the
prior art, it is an object of the present invention to provide a
liquid crystal display device and a method of producing the same
capable of restraining the generation of electrostatic troubles
attendant on proximate formation of the annular upper-layer
light-shielding film and pads on the TFT substrate without causing
an increase in chip size.
[0018] In order to attain the above object, according to a first
aspect of the present invention, there is provided a liquid crystal
display device including one of a plurality of driving substrates
formed en bloc on a substrate and produced individually by
splitting the substrate along scribed lines, the liquid crystal
display device including: a conductive light-shielding film formed
annularly along a peripheral portion of the driving substrate, and
a plurality of pad portions arranged on the inside of the
conductive light-shielding film along one side of the driving
substrate, wherein the spacing between the conductive
light-shielding film and each pad at the side of the driving
substrate where the pad portions are provided is at least 10
.mu.m.
[0019] According to a second aspect of the present invention, there
is provided a method of producing a liquid crystal display device
including one of a plurality of driving substrates formed en bloc
on a substrate and produced individually by splitting the substrate
along scribed lines, the method including: a step of forming a
conductive light-shielding film annularly along a peripheral
portion of the driving substrate, and a step of forming a plurality
of pad portions arranged on the inside of the conductive
light-shielding film along one side of the driving substrate,
wherein the spacing between the conductive light-shielding film and
each pad at the side of the driving substrate where the pad
portions are provided is at least 10 .mu.m.
[0020] In the liquid crystal display device according to the
present invention, the spacing between the conductive
light-shielding film and each pad at the side of the driving
substrate where the pad portions are provided is at least 10
.mu.m.
[0021] The spacing of at least 10 .mu.m has been found to be a
value capable of reducing the rate of troubles occurring due to
static electricity. Therefore, by setting the spacing between the
conductive light-shielding film and each pad to be at least 10
.mu.m, troubles due to static electricity between the conductive
light-shielding film and each pad can be restrained.
[0022] In addition, since the spacing of at least 10 .mu.m between
the conductive light-shielding film and each pad is provided only
at the side of the driving substrate where the pad portions are
disposed, the conductive light-shielding film is not spaced away
from the center along the entire periphery of the driving
substrate, and the desired layout can be realized without much
enlarging the chip size.
[0023] Also, in the method of producing a liquid crystal display
device according to the present invention, the spacing between the
conductive light-shielding film and each pad at the side of the
driving substrate where the pad portions are provided is set to be
at least 10 .mu.m.
[0024] Therefore, by setting the spacing between the conductive
light-shielding film and each pad to be at least 10 .mu.m, troubles
due to static electricity between the conductive light-shielding
film and each pad can be restrained.
[0025] Besides, the spacing of at least 10 .mu.m between the
conductive light-shielding film and each pad is provided only at
the side of the driving substrate where the pad portions are
provided, the conductive light-shielding film is not spaced away
from the center along the entire periphery of the driving
substrate, and the desired layout can be realized without much
increasing the chip size.
[0026] The above and other objects, features and advantages of the
present invention will become apparent from the following
description and appended claims, taken in conjunction with the
accompanying drawings which show by way of example some preferred
embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1 is a plan view of major part showing the layout
relationship of pad portions and a conductive light-shielding film
on a TFT substrate of a liquid crystal display device according to
a first embodiment of the present invention;
[0028] FIG. 2 is a plan view of major part showing the layout
relationship of pad portions and a conductive light-shielding film
on a TFT substrate of a liquid crystal display device according to
a second embodiment of the present invention;
[0029] FIG. 3 is a plan view showing an example of a wiring pattern
on a TFT substrate according to the prior art;
[0030] FIG. 4 is a partly sectional view showing the internal
laminated structure in a region shown by line AA of FIG. 3; and
[0031] FIG. 5 is a plan view of major part showing the layout
relationship of pad portions and a conductive light-shielding film
on the TFT substrate shown in FIG. 3.
DETAILED DESCRIPTION OF THE RPEFERRED EMBODIMENTS
[0032] Now, embodiments of a liquid crystal display device and a
method of producing the same according to the present invention
will be described.
[0033] FIG. 1 is a plan view of major part showing the layout
relationship of pad portions and a conductive light-shielding film
on a TFT substrate of a liquid crystal display device according to
a first embodiment of the present invention.
[0034] The TFT substrates 110 of this embodiment are formed in
regions demarcated by scribed lines (omitted in FIG. 1) formed in a
grating form on a wafer 101, and a plurality of the TFT substrates
110 are formed en bloc by splitting the wafer 101 along the scribed
lines.
[0035] The TFT substrate 110 is provided with a display region 112
in which pixel transistors (omitted in FIG. 1) are disposed in a
matrix form at a central area. A vertical driving circuit 113 and a
horizontal driving circuit 114 for driving each of the pixel
transistors in the display region 112 are provided on the outside
of the display region 112. Further, a metallic wiring 115 and a
plurality of pad portions 116 are provided on the outside of the
driving circuits 113 and 114.
[0036] The pad portions 116 are arranged in parallel with and along
one side of the display region 112 where the horizontal driving
circuit 114 is provided. The pad portions 116 are connected to the
metallic wiring 115, and are brought into contact with terminals of
an inspection apparatus or the like. Some of the pad portions 116
are provided as dummies which are not connected to the metallic
wiring 115.
[0037] Common electrode portions 115A are provided at corner
portions of the metallic wiring 115, whereby electric power is
supplied to each of the driving circuits 113, 114 and the like.
[0038] A conductive light-shielding film 124 is provided on the
outside of the metallic wiring 115 and the pad portions 116.
[0039] The conductive light-shielding film 124 is formed in a
tetragonal annular shape along the outer periphery of the TFT
substrate 110, and is left in the annular form along the outer
periphery of the TFT substrate 110 to ensure that, when an
upper-layer light-shielding film is formed on the TFT substrate
110, the upper-layer light-shielding film on the side of the
scribed lines would not easily be exfoliated at the time of etching
or cleaning.
[0040] The conductive light-shielding film 124 can be formed in a
thickness of 50 to 500 nm by use of a combination of W, Mo, Ta, Cr,
Ti, Al, Cu, Zn, silicides of these elements and alloys of these
elements. The conductive light-shielding film 124 has a low
resistance of not more than 200 K.OMEGA./.quadrature., and has a
transmittance to at least light in the range of 400 to 500 nm of
not more than 10%.
[0041] In this embodiment, the position of the conductive
light-shielding film 124A disposed on the outside of the pad
portions 116 is shifted outwards by 147 nm as compared with the
prior art (shown by broken line 24B in FIG. 1) shown in FIG. 5,
whereby the spacing between the conductive light-shielding film
124A and the pad portions 116 is set to be, for example, not less
than 10 .mu.m.
[0042] Namely, as shown in FIG. 1, of the annular conductive
light-shielding film 124, only the conductive light-shielding film
124A at the portion where the pad portions 116 are arranged is
formed on the outer side by 147 nm.
[0043] Attendant on such a change in the position and shape of the
conductive light-shielding film 124, the position and shape of the
scribed line are also set according to the conductive
light-shielding film 124, 124A.
[0044] In the case of producing such a TFT substrate, for example,
films of Al, TiON and Ti are sequentially formed in thicknesses of
100 nm, 50 nm and 100 nm, and are patterned by etching and the
like, whereby a belt-like pattern with a width of 6 .mu.m in plan
view is formed.
[0045] Thereafter, a film of P-TEOS is provided in a thickness of
100 nm, then a film of SOG is provided in a thickness of 400 nm to
form an interlayer insulation film, a contact hole is opened, and
transparent pixel electrodes consisting of an ITO film with a
thickness of 70 nm are formed.
[0046] With such a structure, a press bonding margin in press
bonding between the pad portions and a flexible substrate is
enlarged, and possibility of shortcircuit between the pad portions
and the flexible substrate due to static electricity can be
reduced.
[0047] While in the above example, of the annular conductive
light-shielding film 124, the conductive light-shielding film 124A
in the range where the PAD portions 116 are arranged is spaced
apart from the PAD portions 116, of the conductive light-shielding
film 124, the conductive light-shielding film 124A along the side
where the PAD portions 116 are arranged may be entirely spaced
apart from the PAD portions 116.
[0048] In this case, the other points of constitution are the same
as in the example shown in FIG. 1, and the description thereof is
omitted.
[0049] While in the above example the conductive light-shielding
film is left at an outer peripheral portion of the TFT substrate
after the TFT substrates are separated from the wafer at the
scribed lines, the conductive light-shielding film may be formed at
a position largely retracted from the PAD portions so that the
conductive light-shielding film is also cut away when the TFT
substrates are separated from the wafer at the scribed lines.
[0050] According to such a method of fabrication, the conductive
light-shielding film is absent in the vicinity of the pad portions
at the time of press bonding between the pad portions and the
flexible substrate, so that the possibility of shortcicuit between
the PAD substrate and the flexible substrate due to static
electricity can be reduced more assuredly.
[0051] Incidentally, in the embodiment as described above, a
certain effect can be obtained if the position of the conductive
light-shielding film 124A is spaced from the PAD portions by not
less than 5 .mu.m. For obtaining an assured effect, however, the
spacing is set to be not less than 10 .mu.m, with a more preferable
range of the spacing being 150 to 200 .mu.m.
[0052] Besides, since the conductive light-shielding film is a
cause of capacitance of coupling with adjacent wiring, the
conductive light-shielding film preferably has a low resistance of
not more than 100 K.OMEGA./.quadrature., more preferably not more
than 10 K.OMEGA./.quadrature..
* * * * *