U.S. patent application number 10/291373 was filed with the patent office on 2003-06-26 for liquid crystal display and method for fabricating the same.
This patent application is currently assigned to LG.Philips LCD Co., Ltd.. Invention is credited to Chin, Gyo Won, Ryu, Ho Jin.
Application Number | 20030117568 10/291373 |
Document ID | / |
Family ID | 19717333 |
Filed Date | 2003-06-26 |
United States Patent
Application |
20030117568 |
Kind Code |
A1 |
Chin, Gyo Won ; et
al. |
June 26, 2003 |
LIQUID CRYSTAL DISPLAY AND METHOD FOR FABRICATING THE SAME
Abstract
A liquid crystal display device, includes a substrate having an
active region and a periphery region, an insulating film formed on
the substrate, a passivation film formed on the insulating film and
having a plurality of first and second contact holes formed along a
circumference of the active region, a first seal pattern formed on
the passivation film along a direction of the first contacts holes,
and a second seal pattern formed on the passivation film along a
direction of the second contact holes.
Inventors: |
Chin, Gyo Won; (Seoul,
KR) ; Ryu, Ho Jin; (Anyang-shi, KR) |
Correspondence
Address: |
MORGAN LEWIS & BOCKIUS LLP
1111 PENNSYLVANIA AVENUE NW
WASHINGTON
DC
20004
US
|
Assignee: |
LG.Philips LCD Co., Ltd.
|
Family ID: |
19717333 |
Appl. No.: |
10/291373 |
Filed: |
November 12, 2002 |
Current U.S.
Class: |
349/153 |
Current CPC
Class: |
G02F 1/1345 20130101;
G02F 1/1339 20130101 |
Class at
Publication: |
349/153 |
International
Class: |
G02F 001/1339 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 20, 2001 |
KR |
P2001-81871 |
Claims
What is claimed is:
1. A liquid crystal display device, comprising: a substrate having
an active region and a periphery region; an insulating film formed
on the substrate; a passivation film formed on the insulating film
and having a plurality of first and second contact holes formed
along a circumference of the active region; a first seal pattern
formed on the passivation film along a direction of the first
contact holes; and a second seal pattern formed on the passivation
film along a direction of the second contact holes.
2. The device according to claim 1, wherein the plurality of first
contact holes are closer to the active region than the plurality of
second contact holes.
3. The device according to claim 1, wherein a size of the plurality
of first contact holes is equal to a size of the plurality of
second contact holes.
4. The device according to claim 1, wherein an interval between the
plurality of first contact holes is equal to an interval between
the plurality of second contact holes.
5. The device according to claim 1, wherein the passivation film
includes an organic insulating material.
6. The device according to claim 1, wherein predetermined portions
of the first and second seal patterns are formed on the insulating
film within the first and second contact holes, respectively.
7. A liquid crystal display device, comprising: a first substrate
having an active region, a gate insulating film, and a plurality
of-thin film transistors; a second substrate having a color filter
layer; a passivation film formed on the gate insulating film and
having a plurality of first and second contact holes formed along a
circumference of the active region, the first contact holes located
closer to the active region than the second contact holes; an
active seal pattern formed on the gate insulating film within the
first contact holes and on a predetermined portion of the
passivation film; a dummy seal pattern formed on the gate
insulating film within the second contact holes and on a
predetermined portion of the passivation film; and a liquid crystal
material layer formed between the first and second substrates.
8. The device according to claim 7, wherein a size of the first
contact holes is equal to a size of the second contact holes.
9. The device according to claim 7, wherein an interval between the
plurality of first contact holes is equal to an interval between
the plurality of second contact holes.
10. The device according to claim 7, wherein the passivation film
includes an organic insulating material.
11. A method for fabricating a liquid crystal display device,
comprising steps of: forming a gate insulating film and a plurality
of thin film transistors within an active region of a first
substrate; forming a passivation film on the gate insulating film
and the thin film transistors; forming a plurality of first and
second contact holes along a circumference of the active region by
removing portions of the passivation film; forming an active seal
pattern along a direction of the plurality of first contact holes
and a dummy seal pattern along a direction of the plurality of
second contact holes; and bonding a second substrate onto the first
substrate.
12. The method according to claim 11, wherein the active and dummy
seal patterns are formed using an equal amount of spraying
material.
13. The method according to claim 11, wherein a size of the second
contact holes is equal to a size of the first contact holes.
14. The method according to claim 11, wherein an interval between
the plurality of first contact holes is equal to an interval
between the plurality of second contact holes.
15. The method according to claim 11, wherein the active seal
pattern is formed on the gate insulating film within the first
contact holes and on a predetermined portion of the passivation
film.
16. The method according to claim 11, wherein the dummy seal
pattern is formed on the gate insulating film within the second
contact holes and on a predetermined portion of the passivation
film.
Description
[0001] The present invention claims the benefit of Korean Patent
Application No. P2001-81871 filed in Korea on Dec. 20, 2001, which
is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a liquid crystal display
(LCD) device, and more particularly, and to an LCD device and a
method for fabricating the same, in which an adhesive power of
upper and lower substrates is improved and a cell gap is uniformly
maintained.
[0004] 2. Discussion of the Prior Art
[0005] Generally, an LCD device is commonly used as a substitute
for a cathode ray tube (CRT) because of its high contrast ratio,
suitability for displaying gray scales or moving pictures, and low
power consumption. The liquid crystal display device for displaying
images by external signals includes a thin film transistor (TFT)
substrate, a color filter substrate, and a liquid crystal material
layer. The TFT substrate has a TFT and a pixel electrode formed in
each pixel region defined by gate and data lines. On the color
filter substrate, a color filter layer and a common electrode are
formed and the liquid crystal material layer is interposed between
the two substrates. Presently, a spacer is inserted between the two
substrates to leave a uniform space between them, and a sealant is
formed along edges of the substrates to completely bond the two
substrates together. The sealant prevents the liquid crystal
material from flowing outside, and maintains a constant interval
between the two substrates along a periphery of an active
region.
[0006] A method for fabricating an LCD device according to the
related art will be described below with reference to the
accompanying drawings.
[0007] FIG. 1 is a cross sectional view of an LCD device according
to the related art.
[0008] In FIG. 1, an LCD device includes upper and lower substrates
18 and 19 and a liquid crystal material layer 20 formed there
between. A black matrix 11 for preventing a light leakage, a color
filter 12 for displaying colors, and a common electrode 13 for
applying a voltage to the liquid crystal layer 20 are formed on the
upper substrate 18. Gate and data lines (not show) are formed on
the lower substrate 19 and cross each other to define a pixel, a
TFT 21 is formed at the crossings of the gate and data lines for
switching a signal, and a pixel electrode 22 is formed on the
liquid crystal material layer 20 forming an electric field by being
provided with the signal from the TFT 21. In addition, an
insulating film 27 is formed between the gate and data lines for
insulating the gate and data lines from each other and a
passivation film 28 is formed between the TFT 21 and the pixel
electrode 22.
[0009] At this time, the gate insulting film 27 is deposited by a
plasma enhanced chemical vapor deposition (PECVD) method using an
inorganic material that closely adheres to the metal, and has an
excellent insulating property, such as SiNx or SiOx, BCB or an
acryl resin having a low dielectric constant property is used for a
material of the passivation film 28. Additionally, a ball spacer 16
is inserted between the upper and lower substrates 18 and 19 and a
seal pattern is formed on along the edges of the substrates for
maintaining the interval of the two substrates.
[0010] In FIG. 2, the seal pattern is divided into an active seal
pattern 14 and a dummy seal pattern 15. The active seal pattern 14
is formed along a circumference of an effective display area 13,
thereby forming a cell gap and preventing a leakage of the liquid
crystal material. The dummy seal pattern 15 is formed outside the
active seal pattern 14, thereby absorbing vibrational shock
generated during scribing and breaking process. The active and
dummy seal patterns 14 and 15 are formed with an equal amount of a
spray material, without being formed on an inlet 30 for the liquid
crystal material. The active and dummy seal patterns 14 and 15 are
formed by a screen printing method or a dispensing method using a
thermosetting adhesive with a micro pearl material.
[0011] In FIG. 3. during the screen printing method, a screen mask
51 with a predetermined pattern is placed on the substrate 52, and
a thermosetting adhesive 53 is dropped on the screen mask 51. Then,
the thermosetting adhesive 53 is printed on the substrate 52 by a
rubber squeezer. Accordingly, a seal pattern is formed on the
substrate 52 as the thermosetting adhesive passes through the inlet
of the screen mask 51.
[0012] During the dispensing method, the adhesive material is
sprayed by compression of a sprayer filled with a thermosetting
adhesive. Accordingly, a predetermined pattern is formed on the
substrate to form a seal pattern.
[0013] In both methods, it is problematic to control the amount of
spray material for forming the seal pattern. In addition, when the
liquid crystal material is injected between the substrates, the
liquid crystal material may leak through the space between the seal
pattern and the passivation film 28 due to a lower adhesive
strength of the sealant and organic insulating film.
[0014] In FIGS. 4A and 4B, a contact hole 29 is formed on the lower
part of the active seal pattern 14. Accordingly, the active seal
pattern 14 contacts the gate insulating film 12, thereby improving
the adhesive strength of the sealant and organic irritating
film.
[0015] In FIG. 4B, a step difference (b-a) is generated between the
active and dummy seal patterns 14 and 15. Because of the step
difference, intervals between the upper and lower substrates become
uneven, and the liquid crystal material may flow outside the
substrates since the active seal pattern 14 does not adhere to the
upper substrate. Controlling the amount of spraying material can be
one way to reduce the step difference between the active and dummy
seal patterns 14 and 15. However, controlling the amount of spray
material remains difficult.
SUMMARY OF THE INVENTION
[0016] Accordingly, the present invention is directed to a liquid
crystal display device and a method for fabricating the same that
substantially obviates one or more problems due to limitations and
disadvantages of the prior art.
[0017] An object of the present invention is to provide an LCD
device and a method for fabricating the same, in which a uniform
cell gap is maintained and an adhesive strength between upper and
lower substrates is improved.
[0018] Additional advantages, objects, and features of the
invention will be set forth in part in the description which
follows and in part will become apparent to those having ordinary
skill in the art upon examination of the following or may be
learned from practice of the invention. The objectives and other
advantages of the invention may be realized and attained by the
structure particularly pointed out in the written description and
claims hereof as well as the appended drawings.
[0019] To achieve these objects and other advantages and in
accordance with the purpose of the invention, as embodied and
broadly described herein, a liquid crystal display device, includes
a substrate having an active region and a periphery region; an
insulating film formed on the substrate; a passivation film formed
on the insulating film and having a plurality of first and second
contact holes formed along a circumference of the active region; a
first seal pattern formed on the passivation film along a direction
of the first contact holes; and a second seal pattern formed on the
passivation film along a direction of the second contact holes.
[0020] In another aspect of the invention, a liquid crystal display
device, includes a first substrate having an active region, a gate
insulating film, and a plurality of thin film transistors; a second
substrate having a color filter layer; a passivation film formed on
the gate insulating film and having a plurality of first and second
contact holes formed along a circumference of the active region, in
which the first contact holes are located to the active region than
the second contact holes; an active seal pattern formed on the gate
insulating film within the first contact holes and on a
predetermined portion of the passivation film; a dummy seal pattern
formed on the gate insulating film within the second contact holes
and on a predetermined portion of the passivation film; and a
liquid crystal material layer formed between the first and second
substrates.
[0021] In another aspect of the present invention, a method of
fabricating a liquid crystal display device includes the steps of
forming a gate insulating film and a plurality of thin film
transistors within an active region of a first substrate, forming a
passivation film on the gate insulating film and the thin film
transistors, forming a plurality of first and second contact holes
along a circumference of the active region by removing portions of
the passivation film, forming an active seal pattern along a
direction of the plurality of first contact holes and a dummy seal
pattern along a direction of the plurality of second contact holes,
and bonding a second substrate onto the first substrate.
[0022] It is to be understood that both the foregoing general
description and the following detailed description of the present
invention are exemplary and explanatory and are intended to provide
further explanation of the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The accompanying drawings, which are included to provide a
further understanding of the invention and are incorporated in and
constitute a part of this application, illustrate embodiment(s) of
the invention and together with the description serve to explain
the principle of the invention. In the drawings:
[0024] FIG. 1 is a cross sectional view of an LCD device, according
to the related art.
[0025] FIG. 2 is a plane view illustrating a seal pattern of an LCD
device, according to the related art.
[0026] FIG. 3 is a cross sectional view illustrating a sealant
printing apparatus for describing a screen printing method,
according to the related art.
[0027] FIG. 4A is a plane view of an LCD device, according to the
related art.
[0028] FIG. 4B is a cross sectional view taken along I-I' of FIG.
4A, according to the related art.
[0029] FIG. 5 is a plane view of an exemplary LCD device, according
to the present invention.
[0030] FIGS. 6A to 6E are cross sectional views along II-II' of
FIG. 5 according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0031] Reference will now be made in detail to the preferred
embodiments of the present invention, examples of which are
illustrated in the accompanying drawings.
[0032] FIG. 5 is a plane view of an exemplary LCD device according
to the present invention and FIGS. 6A to 6E are cross sectional
views taken along the line II-II' of FIG. 5, according to the
present invention.
[0033] In FIG. 5 the LCD device may include upper and lower
substrates 118 and 119, and a liquid crystal material layer
disposed therebetween. Accordingly, the lower substrate may be
divided into an active region 113 and a periphery part.
[0034] In FIGS. 6A to 6E the lower substrate 119 may include gate
and data lines (not shown), a gate insulating film 127, a TFT (not
shown), a passivation film 128, and a pixel electrode (not shown).
The gate and data lines may be formed to cross each other, and may
deliver signals. The gate insulating film 127 may be interposed
between the gate and data lines (not shown) to insulate them from
each other. The TFT (not shown) formed at the crossings of the gate
and data lines may switch the signals transmitted along the gate
and data lines. The passivation film 128 may be formed on an entire
surface of the lower substrate 119 including the TFT by depositing
an organic insulating material for example. The pixel electrode may
be connected to the TFT on the passivation film 128, and thereby
forming an electric field with a common electrode (not shown).
[0035] In addition, the gate insulating film 127 and the
passivation film 128 may be deposited on the entire surface of the
lower substrate 119 to be extended along the periphery of the
active region 113.
[0036] In FIG. 5, a plurality of first and second contact holes 129
and 130 may be formed along the circumference of the active region
113 on the passivation film 128 for exposing the gate insulating
film 127. The first contact holes 129 may be closer to the active
region 113 than the second contact holes 130. The active seal
pattern 114 may be formed along the circumference of the active
region 113 along a direction of the first contact holes 129,
thereby preventing leakage of the liquid crystal material and
maintaining a uniform cell gap between the upper and lower
substrates 118 and 119. Accordingly, the active seal pattern 114
may be formed on predetermined portions of both the passivation
film 128 and the exposed gate insulating film 127.
[0037] The dummy seal pattern 115 may be formed on the outer part
of the active seal pattern 114 to absorb vibrational shock during
the scribing and breaking process. In addition the dummy seal
pattern 115 may maintain a uniform cell gap along the periphery of
the active region 113. Accordingly, the dummy seal pattern 115 may
be formed on predetermined portions of both the passivation film
128 and the exposed gate insulating film 127, along a direction of
the second contact holes 130. In addition, neither the active seal
pattern 114 nor the dummy seal pattern 115 may be formed on a
liquid crystal material inlet to which a liquid crystal material
may be injected for example.
[0038] As described above, the LCD device may include a plurality
of the second contact holes 130 and a plurality of the first
contact holes 129. The first contact holes 129 may be formed on the
lower part of the active seal pattern 114 to improve adhesive
strength between the passivation film 128 and the active seal
pattern 115. The second contact holes 130 may be formed on the
lower part of the dummy seal pattern 115 to prevent generation of a
step difference with the passivation film 128. The second contact
holes 130 may have a same size and interval as the first contact
holes 129. Alternatively, the first and second contact holes 129
and 130 may have different sizes and different intervals.
[0039] Accordingly, the active and dummy seal patterns 114 and 115
may be attached to the gate insulating film 127 of the lower part
of the passivation film 128 through the first and second contact
holes 129 and 130. Thus, the active and dummy seal patterns 114 and
115 may have improved adhesive strength.
[0040] In addition, because the contact holes 130 may be formed on
the lower part of the active seal pattern 114 and on the lower part
of the dummy seal pattern 115, the step difference between the
active and dummy seal patterns 114 and 115, which occurs when the
contact holes are formed only on the lower part of the active seal
pattern 114, may be prevented.
[0041] A method for fabricating an LCD device having the
above-described construction will be described in detail.
[0042] In FIG. 6A, a gate line (as shown), a gate insulating film
127, and a data line (not shown) may be sequentially formed on the
lower substrate 119. In addition, on the crossings of the gate and
data lines, a TFT that includes a gate electrode, a gate insulating
film, a semiconductor layer, and source/drain electrodes may be
formed at locations corresponding to intersections of the gate and
data lines. Then, a passivation film 128 may be formed on the
entire surface of the lower substrate 119, including the TFT, by
deposition of an organic insulating film such as BCB and an acrylic
resin.
[0043] In FIGS. 6B and 6C, a plurality of first and second contact
holes 129 and 130 may be formed by selectively eliminating the
passivation film 128 after spreading a photoresist 140 on the
passivation film 128, and patterning the photoresist 140.
Accordingly, portions of gate insulating film 127 may be exposed.
The first and second contact holes 129 and 130 may be formed along
the circumference of the active region 113. In addition, the first
contact holes 129 may be formed to be closer to the active region
113 than the second contact holes 130. Then the photoresist 140 may
be eliminated, and a pixel electrode made of ITO may be formed on
the passivation film 128 to be connected to the TFT.
[0044] In FIG. 6D, the active and dummy seal patterns 114 and 115
may be formed on a predetermined portion of the periphery of the
active region 113 by a screen printing method, or a dispensing
method, for example. The active seal pattern 114 may be formed on a
predetermined portion of the gate insulating film 127 that is
exposed by the first contact holes 129, and on a predetermined
portion of the passivation film 128. The dummy seal pattern 115 may
be formed on a predetermined portion of the gate insulating film
127 that is exposed by the second contact holes 130, and on a
predetermined portion of the passivation film 128.
[0045] Accordingly, since the step difference between the active
and dummy seal patterns 114 and 115 is prevented, a cell gap along
the periphery of the active region 113 is uniformly maintained. In
addition, the adhesive strength of the upper and lower substrates
118 and 119 maybe improved by supplementing a poor adhesive
strength between the dummy seal pattern 115 and the passivation
film 128.
[0046] In FIG. 6E, an upper substrate 118 upon which a color filter
layer may be formed may be bonded to the lower substrate 119. The
upper and lower substrates 118 and 119 may be completely bonded as
the active and dummy seal patterns 114 and 115 are hardened using
heat and pressure. The seal patterns may be formed of high-polymers
having excellent adhesive power, such as an epoxy resin,
thermosetting resin, and photo-setting resin. A spacer may be
inserted between the upper and lower substrates 118 and 119 to
maintain a cell gap on the active region 113. The cell gap
maintained by the spacer may also be uniformly maintained along the
periphery of the active region 113 by the seal patterns 114 and
115. Substantially, a liquid crystal material layer of about 1-9
.mu.m may be formed between the upper and lower substrates 118 and
119. To cut the upper and lower substrates 118 and 119 in to a
panel unit, a scribe line may be formed on a surface of one of the
upper and lower substrates 118 and 119 using a scribe wheel for
example. Then, a breaking process may be performed. Accordingly,
the scribe line may be formed parallel with the active and dummy
seal patterns 114 and 115.
[0047] The method of forming the liquid crystal material layer may
be divided into a liquid crystal injection type and a liquid
crystal dropping type. In the liquid crystal injection type method,
the upper and lower substrates may be bonded together and an
interior pressure of the liquid crystal cell may be reduced. Then,
a liquid crystal material may be injected between the upper and
lower substrates 118 and 119 by capillary action. In the liquid
crystal dropping type method, the liquid crystal material may be
evenly applied onto one of the substrates and the substrates are
bonded together.
[0048] Next, after a washing process that eliminates alien
substances from the panel, the panel may be checked for flaws by
visual inspection and by application of an electric signal. Then, a
module process may be performed to finish the LCD device. During
the process, a polarized light plate may be attached onto the
surface of the substrate of the liquid crystal panel, and an
external driving circuit may be connected to the liquid crystal
panel. In addition, a backlight may be installed as a light
source.
[0049] It will be apparent to those skilled in the art that various
modifications and variations can be made in the LCD device and
method of fabricating the same without departing from the spirit or
scope of the invention. Thus, it is intended that the present
invention covers the modifications and variations of this invention
provided they come within the scope of the appended claims and
their equivalents.
* * * * *