Telephonic communications – Emergency or alarm communications – Responsive to sensed nonsystem condition
Reexamination Certificate
2001-12-05
2003-10-28
Dudek, James (Department: 2871)
Telephonic communications
Emergency or alarm communications
Responsive to sensed nonsystem condition
Reexamination Certificate
active
06639971
ABSTRACT:
This application claims the benefit of Korean Patent Application No. P2000-0085556, filed in Korea on Dec. 29, 2000, which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) panel and a method for fabricating the same. More particularly, the present invention relates to a LCD panel and a method for fabricating the same in which light leakage resulting from a rubbing defect is prevented from occurring in a contact hole during a rubbing process.
2. Background of the Related Art
A related art LCD panel will be described with reference to the accompanying drawings.
FIG. 1
is a perspective view of the related art LCD panel, in which a unit pixel region of the LCD panel is shown.
FIG. 2A
is a sectional view taken along line I-I′ of FIG.
1
.
FIG. 2B
is a sectional view taken along line II-II′ of FIG.
1
.
FIG. 3A
is a detailed sectional view showing a portion “A” of FIG.
2
A.
FIG. 3B
is a detailed sectional view showing a portion “B” of FIG.
2
B.
As shown in
FIG. 1
, in the related art LCD panel, a gate line
11
is arranged on a first substrate (transparent substrate)
10
, crossing a data line
15
defining a pixel region. A pixel electrode
17
made of a transparent conductive film is formed in each pixel region. A thin film transistor (TFT) is formed in each pixel region by switching a signal of the gate line
11
to the data line
15
to the pixel electrode
17
.
The TFT includes a gate electrode
11
a
projecting from the gate line
11
on the first substrate
10
. A semiconductor film
13
is formed below the data line
15
and in a TFT region. Then, a source electrode
15
a
is formed on the semiconductor film
13
to be connected with the data line
15
and to be overlapped with the gate electrode
11
a
. A drain electrode
15
b
is formed on the semiconductor film
13
opposite to the source electrode
15
a
to overlap the gate electrode
11
a
, and connected with the pixel electrode
17
through a contact hole
18
a.
Also, a storage electrode
15
c
is formed on the gate line
11
to overlap the gate line
11
, and is connected with the pixel electrode
17
through a contact hole
18
b.
In a second substrate (not shown), a light-shielding film (not shown) is formed above the gate line
11
, the data line
15
, and the TFT to prevent light from leaking in the gate line
11
, the data line
15
, and the TFT.
A method for fabricating the aforementioned related art LCD panel will be described as follows.
As shown in FIG.
2
A and
FIG. 2B
, the gate line
11
and the gate electrode
11
a
are simultaneously formed on the first substrate
10
.
A gate insulating film
12
is formed on an entire surface of the first substrate to cover the gate electrode
11
a
and the gate line
11
. Then, the semiconductor film
13
and an ohmic contact film
14
are formed on the gate insulating film
12
.
Subsequently, a metal is deposited on the entire surface of the first substrate
10
, and then patterned to form the data line
15
perpendicular to the gate line
11
. The source and drain electrodes
15
a
and
15
b
are simultaneously formed with the data line
15
, and the storage electrode
15
c
is formed above the gate line
11
at the same time. Then, a passivation film
16
is formed on the resulting structure.
The passivation film
16
, the drain electrode
15
b
, the ohmic contact film
14
, the semiconductor film
13
, and the gate insulating film
12
are etched in a predetermined portion of the drain electrode
15
b
, thereby forming the contact hole
18
a
. Also, the passivation film
16
, the storage electrode
15
c
, and the gate insulating film
12
are selectively removed in a predetermined portion of the storage electrode
15
c
, forming the second contact hole
18
b
. Then, the pixel electrode
17
is respectively connected with the drain and storage electrodes
15
b
and
15
c
in the pixel region.
If a voltage is applied between the pixel electrode
17
and a common electrode (not shown) to drive the LCD panel, an arrangement of molecules in a liquid crystal film is changed due to the voltage. To keep a constant arrangement of the molecules during a unit frame, a constant voltage applied to the liquid crystal film is required. Accordingly, the storage electrode
15
c
and the gate line
11
form a storage capacitor keeping the applied voltage to the liquid crystal molecules consistent.
Although not shown, an alignment film is deposited on the entire surface of the substrate, and rubbed to determine a direction of the molecules in the liquid crystal film.
However, the related art LCD panel has the following problems.
First, during rubbing, defects occur on the alignment of the molecules above the first and second contact holes. Accordingly, back light formed at the rear of the first substrate
10
passes through a portion that is defectively rubbed, causing light leakage.
Secondly, in a structure using an overcoat film (flattening film) of organic insulating film such as passivation film
16
, high step coverage occurs at the first/second contact holes
18
a
and
18
b
. That is, the alignment film is not completely formed in the contact holes during the rubbing process. Thus, resulting in randomly arranged liquid crystals in the portions where the contact holes are formed, during driving of the panel. Therefore, light leakage occurs as the back light passes through the contact holes.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a liquid crystal display panel and a method for fabricating the same that substantially obviate one or more problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a liquid crystal display panel and a method for fabricating the same in which a metal film is simultaneously formed with a gate line in a lower portion of contact holes. The contact holes being formed to respectively connect a storage electrode and a drain electrode with pixel electrodes, thus preventing light from leaking in the contact holes due to a rubbing defect.
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 aspects and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, an LCD panel of the present invention includes a substrate, a gate line on the substrate at a constant distance in one direction, a data line, source/drain electrodes, and a storage electrode arranged to cross the gate line at a constant distance. Additionally, the present invention includes a first contact hole in the drain electrode, a pixel electrode connected with the drain electrode through the first contact hole in a pixel region, and a first pattern below the first contact hole to shield light.
Preferably, the LCD panel further includes a storage electrode formed on the gate line to overlap the gate line, a second contact hole in the storage electrode, and a second pattern formed below the second contact hole to connect the pixel electrode with the storage electrode and to shield light.
Preferably, the first and second patterns are formed of the same material as that of the gate line.
In another aspect of the present invention, a method for fabricating an LCD panel includes forming a gate line having gate electrodes on a substrate, and simultaneously forming a pattern in a portion where a drain electrode of a TFT is connected with a pixel electrode, forming a gate insulating film on an entire surface of the first substrate, forming an active film on the gate insulating film above the gate electrode, forming a data line on the gate insulating film perpend
Kim Ki Tae
Kwak Dong Yeung
Dudek James
LG.Philips LCD Co. , Ltd.
Morgan & Lewis & Bockius, LLP
LandOfFree
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