Liquid crystal cells – elements and systems – Particular excitation of liquid crystal – Electrical excitation of liquid crystal
Reexamination Certificate
2000-10-30
2002-10-08
Ullah, Akm E. (Department: 2871)
Liquid crystal cells, elements and systems
Particular excitation of liquid crystal
Electrical excitation of liquid crystal
C257S057000
Reexamination Certificate
active
06462793
ABSTRACT:
This application claims the benefit of Korean Patent Application No. 1999-47296, filed on Oct. 28, 1999, which is hereby incorporated by reference for all purposes as if fully set forth herein.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a technique for preventing a defect caused by static electricity in a process of fabricating a substrate of a liquid crystal display, and more particularly a method of fabricating a liquid crystal display wherein gate metal film patterns are connected to each other by a connecting pattern, and thereafter the connection of the gate metal film is separated when a data metal film pattern and/or an indium tin oxide (ITO) film pattern are formed so as to prevent an insulation breakage of a gate insulating film caused by a static electricity in a process of depositing the gate insulating film.
2. Description of the Related Art
Generally, as shown in
FIG. 1
, a liquid crystal display (LCD) has thin film transistors (TFT's)
25
arranged at each intersection between gate bus lines
20
and data bus lines
30
. Each of pixel electrodes
40
provided at an area surrounded by a gate bus line
20
and a data bus line
30
is connected to each output terminal a corresponding one of the TFT's
25
. A gate driver
21
for driving the gate bus lines
20
is connected to the ends of the gate bus lines
20
, and a data driver
31
for driving the data bus lines
30
is connected to the ends of the data bus lines
30
.
The gate driver
21
and the data driver
31
have employed a structure in which devices such as TFT's are provided at the peripheral of a pixel array of the substrate in accordance with a development of an integrated circuit technique.
FIG. 2
shows an example of the conventional driver circuit for driving one line. In
FIG. 2
, the driver circuit is configured by a serial and parallel combination of six TFT's. Herein, a is a terminal connected to one gate line, and b
1
, b
2
, b
3
and b
4
are connecting terminals of the driver circuit.
FIG. 4
is a plan view showing an exemplary structure of a conventional LCD substrate including the driver circuit. The LCD substrate includes a pixel array provided with gate bus lines
20
, data bus lines
30
, pixel electrodes
40
and TFT's
25
, and a driver circuit
16
. In
FIG. 4
, a reference numeral
17
represents a gate start lead line.
Hereinafter, a process of fabricating the conventional LCD substrate will be described in detail with reference to
FIG. 3
, FIG.
5
and FIG.
6
. FIG.
5
and
FIG. 6
are section views of the LCD substrate taken along the I-I′ line and the II-II′ line in
FIG. 4
, respectively.
First, a buffer layer is provided on a transparent substrate
1
and an amorphous silicon (a-Si) layer is formed into a land-shaped pattern on the buffer layer
2
to provide a semiconductor layer
3
. In turn, a first insulating film
4
made from SiN
x
or SiO
x
and a gate metal film
5
made from Cr, Mo or Al are sequentially disposed and then patterned into the same pattern shape. A gate electrode
20
a
constituting a portion of the gate metal film is formed into a narrower width than the land-shaped semiconductor layer
3
at a portion where TFT is formed by way of the first insulating film
4
on the semiconductor layer
3
. Particularly, the pattern of the gate metal film
5
is formed in such a manner that the array gate bus line
20
, the gate electrode
20
a
, the driver gate bus line
42
, the gate start lead line
17
are separated from each other. Next, an ohmic contact layer is formed by doping each side surface of the semiconductor layer with impurity ions using the patterned gate metal film
5
as a mask.
Subsequently, a second insulating film
7
made from SiN
x
or SiO
x
is deposited as shown in FIG.
7
A. Since the gate metal film
5
constituting the gate electrode
2
a
, etc. has been floated in a deposition process of the second insulating film
7
and exposed to a plasma in a deposition equipment, a potential difference caused by a static electricity is generated at the separated gate metal film
5
, that is, between the array gate bus line
20
and the driver gate bus line
42
. Thus, an insulation breakage may be caused on the second insulating film
4
to form a gap
50
in the second insulating film
7
.
If a first contact hole
11
for exposing each side surface of the semiconductor layer
3
is formed in the second insulating film
7
in such a state that the gap
50
has been formed in the second insulating film
7
as mentioned above, then an etchant is penetrated through the gap
50
to damage the gate metal film
5
. Also, if the data metal film
43
is formed on the second insulating film
7
, then a short may be generated between the gate metal film
5
and the data metal film
43
through the
50
.
Subsequently, the data metal film
43
is formed into a desired pattern to provide data bus lines
30
, source electrodes
30
a
and a data metal film
8
of the driver. By the pattern formation of the data metal film
43
, the TFT's
25
are provided at the pixel array
15
and the driver circuit
16
of the LCD substrate.
Finally, a third insulating film
9
made from an inorganic insulating material
5
such as SiN
x
or SiO
x
or an organic insulating material such as polyimide is deposited and a second contact hole
12
is formed to expose a partial surface of the drain electrode
30
b
of the TFT included in the pixel array. Thereafter, an ITO film is provided at the entire surface of the third insulating film
9
and then patterned to form the pixel electrode
40
of the pixel array.
As described above, the edge of the LCD substrate provided with the driver circuit has such a structure that the TFT's are arranged as shown in FIG.
6
and then the third protective film
9
is provided to cover the TFT's, whereas the pixel array thereof has such a structure that the TFT's are arranged as shown in FIG.
5
and then the pixel electrodes
40
contacting the drain electrodes of the TFT's are provided.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a liquid crystal display device and method of fabricating the same that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention to provide a method of fabricating a liquid crystal display device that is adapted for preventing an insulation breakage of an insulating film caused by a static electricity.
A further object of the present invention is to provide a method of fabricating a liquid crystal display device that is adapted for preventing a short between a gate metal film and a data metal film caused by an insulation breakage of an insulating film.
A still further object of the present invention is to provide a method of fabricating a liquid crystal display device that is adaptive for preventing a damage of a gate metal film caused by an insulation breakage of an insulating film.
A still further object of the present invention is to provide a method of fabricating a liquid crystal display device that is adaptive for preventing an insulation breakage of an insulating film as well as improving a fabrication yield of a liquid crystal display device without any additional mask process.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, a liquid crystal display device according to one aspect of the present invention includes a gate metal film formed at the center of a semiconductor layer with being interleaved with a first insulating film; a connecting metal f
Ha Yong Min
Park Jae Deok
LG. Philips LCD Co. Ltd.
McKenna Long & Aldridge LLP
Ullah Akm E.
LandOfFree
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