Liquid crystal cells – elements and systems – Particular excitation of liquid crystal – Electrical excitation of liquid crystal
Reexamination Certificate
2002-10-24
2003-11-18
Ton, Toan (Department: 2871)
Liquid crystal cells, elements and systems
Particular excitation of liquid crystal
Electrical excitation of liquid crystal
Reexamination Certificate
active
06650380
ABSTRACT:
The present application claims, under 35 U.S.C § 119, the benefit of Korean Patent Application No. P2001-081774 filed Dec. 20, 2001, which is herein fully incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention pertains to a liquid crystal display, and more particularly to a method of fabricating a liquid crystal display device that has improved yield.
2. Description of the Related Art
Generally, a liquid crystal display (LCD) controls the light transmissivity of liquid crystal cells arranged in a matrix pattern in response to a video signal to thereby display a picture corresponding to the video signals on a liquid crystal display panel. To this end, the LCD includes a liquid crystal display panel having liquid crystal cells arranged in an active matrix, and driving integrated circuits (IC's) drive the liquid crystal cells.
The driving IC's are usually manufactured in chip form. The driving IC's are mounted on a tape carrier package (TCP) film attached to the outer periphery of the liquid crystal panel. The driving IC's are connected by a tape automated bonding (TAB) system while being mounted along the edge of the liquid crystal panel, when they are connected by a chips or glass (COG) system. In the TAB system, the driving IC's are electrically connected to a pad portion provided at the liquid crystal panel by means of the TCP.
FIG. 1
is a plan view showing a structure of a conventional LCD device.
In
FIG. 1
, the LCD device has a lower plate
4
and an upper plate
6
that oppositely adhere to each other. The LCD device includes a picture display part
2
having liquid crystal cells arranged in a matrix pattern, and gate pad portions GP and data pad portions DP connected between the driving IC's and the picture display part
2
.
In the picture display part
2
, data lines supplied with data signals and gate lines supplied with gate signals are arranged at the lower plate
4
so as to cross each other. Each of the crossing parts is provided with a thin film transistor for switching the liquid crystal cell, and a pixel electrode connected to the thin film transistor drives the liquid crystal cell. The upper plate
6
includes coated color filters, and the color filters are separated for each cell area by black matrices. A common transparent electrode is coated on the surfaces of the color filters. Upper and lower plates
6
and
4
are spaced from each other by a spacer to provide a cell gap, which is filled with a liquid crystal material. The upper and lower plates
6
and
4
adhere to each other by means of a sealant coated on a seal
10
at the outside of the picture display part
2
.
The edge area of the lower plate
4
that does not overlap with the upper plate
6
is provided with gate pad portions GP and data pad portions DP. The gate pad portion GP applies a gate signal from the gate driving IC to the gate line of the picture display part
2
. The data pad portion DP applies a video signal from the data driving IC to the data line of the picture display part
2
.
In the LCD device having the structure described above, a protective film for protecting the metal electrode and the thin film transistors entirely coats the lower plate
4
. The pixel electrode is formed on the protective film for each cell area. The protective film is an organic protective film that enhances the aperture ratio of the pixel.
As shown in
FIG. 2
, a gate pad
14
of the gate pad portion GP along with a gate line of the picture display part
2
is provided on a lower substrate
1
. A gate insulating film
22
and an organic protective film
24
are sequentially entirely coated on the lower substrate
1
to cover the gate pad
14
. A gate contact hole
16
a
forms by patterning the gate insulating film
22
and the organic protective film
24
to expose a portion of the gate pad
14
. A gate protective electrode
20
is formed on the organic protective film
24
to electrically connect the gate pad
14
to the gate protective electrode
20
via the gate contact hole
16
a.
As shown in
FIG. 3
, a data pad
18
of the data pad part DP along with a data line of the picture display part
2
are provided on the gate insulating film
22
. The organic protective film
24
entirely coats the gate insulating film
22
to cover the data pad
18
. A data contact hole
16
b
forms by patterning the organic protective film
24
to expose a portion of the data pad
18
. A data protective electrode
26
formed on the organic protective film
24
is electrically connected, via the data contact hole
16
b
, to the data pad
18
.
The gate pad portion GP and the data pad portion DP are in contact with the TCP mounted with the driving. IC by the TAB system. The gate pad
14
and the data pad
18
are electrically connected to the TCP via the gate protective electrode
20
and the data protective electrode
26
provided on the organic protective film
24
. This has the goal of preventing damage to the gate pad
14
and the data pad
18
upon repetition of the TCP adhering process required for the TAB system. Also, the gate pad
14
and the data pad
18
are not exposed and hence do not react with peripheral moisture to cause their oxidative corrosion.
In order to electrically connect the TCP to the gate protective electrode
20
and the data protective electrode
26
, an anisotropic conductive film
12
as shown in FIG.
4
A and
FIG. 4B
is provided. The anisotropic conductive film
12
is coated with conductive particles
28
, which form a current path between the TCP, the gate protective electrode
20
and the data protective electrode
26
.
If the data pad portion DP and the gate pad portion GP adhere to the TCP mounted with the driving IC by the TAB system, then it is necessary to repeat the process of adhesive bonding and separating the TCP many times when defects caused by a misalignment occur. Accordingly, as the organic protective film
24
has a weak adhesion characteristic with respect to the gate insulating film
22
, it is removed along with the TCP in the process of separating the TCP. In this case, there is a problem in that unevenness of the surface removed with the organic protective film
24
causes a weak adhesion characteristic upon re-adhering the TCP.
Furthermore, if the organic protective film
24
on the gate pad
14
and the data pad
18
is removed, then the gate protective electrode
20
and the data protective electrode
26
thereon also are removed. Accordingly, there is a problem in that the gate pad
14
and the data pad
18
are exposed to be damaged or oxidized, thereby deteriorating the characteristics of the gate pad
14
and the data pad
18
.
Moreover, if a mask for eliminating the residual organic protective film
24
is used for a smooth repair process, then the productivity is reduced and hence a production time is prolonged.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the invention to provide a method of fabricating a liquid crystal display device that is adapted to improve the yield and overcome problems and disadvantages of the related art.
A method of fabricating a liquid crystal display device according to an embodiment of the present invention, includes forming a gate electrode and a gate pad over a substrate, forming a gate insulating film over the substrate, forming a semiconductor layer over the gate insulating film, forming a source electrode, a drain electrode and a data pad over the gate insulating film, depositing an inorganic insulating material over the gate insulating film, depositing an organic insulating material over the inorganic insulating material, removing selectively the organic insulating material at a partial area over the drain electrode, the gate pad and the data pad to leave a portion of the organic insulating material over the gate pad and the data pad, patterning the inorganic insulating material using at least a portion of the remaining organic insulating material as a mask, thereby providing an organic protective film and a part of an inorganic protective
Birch & Stewart Kolasch & Birch, LLP
LG.Philips LCD Co. , Ltd.
Ton Toan
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