Semiconductor device manufacturing: process – Making field effect device having pair of active regions... – On insulating substrate or layer
Reexamination Certificate
2001-12-28
2003-02-18
Le, Vu A. (Department: 2824)
Semiconductor device manufacturing: process
Making field effect device having pair of active regions...
On insulating substrate or layer
C438S030000, C438S150000, C438S166000, C438S149000
Reexamination Certificate
active
06521491
ABSTRACT:
This application claims the benefit of the Korean Application No. P2001-033261 filed on Jun. 13, 2001, 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) device, and more particularly, to a method for fabricating thin film transistor-LCD using mixture acid in the same equipment.
2. Discussion of the Related Art
Generally, an LCD panel is divided into an upper substrate, a lower substrate, and an LC layer injected between them.
A plurality of gate lines are arranged to cross a plurality of data lines with a constant interval on the lower transparent substrate to define a plurality of pixel regions of a matrix arrangement. A plurality of TFTs are arranged at a crossing point of the gate lines and the data lines. Also, a plurality of pixel electrodes connected to a drain electrode of the respective TFTs are arranged in the respective pixel regions.
A black matrix layer is formed on the upper substrate to prevent light from being transmitted TFTs, gate lines, and data lines arranged on the lower substrate other than the respective pixel regions. Also, a color filter layer for showing colors at parts corresponding to the respective pixel regions is formed on the upper substrate, and a common electrode is formed on an entire surface.
The upper and lower substrates are attached with constant space to form an LC between the upper and lower substrates.
Polarization plates for linearly polarizing a visible ray are respectively attached to both sides of the upper and lower substrates attached to each other.
Hereinafter, a related art LCD device provided with gate lines and data lines formed on the lower substrate, TFTs, and a pixel electrode will be explained.
FIG. 1
is a lay out of a general LCD device.
As shown in
FIG. 1
, a plurality of gate lines
101
are formed to cross a plurality of data lines
102
on an insulating substrate. Also, a gate pad
103
and a data pad
104
are respectively formed at end parts of the respective gate lines
101
and the data lines
102
. TFTs
105
corresponding to a switching device and a pixel electrode (not shown) are formed in a pixel region defined by crossing the respective gate lines
101
and the data lines
102
. Herein, a region consisted of pixel regions of the matrix arrangement becomes an active region where a picture image is realized.
Also, first and second shorting bars
106
and
107
for dividing a plurality of gate lines and data lines into odd and even lines and combining into one are formed at an inner side of an edge of the substrate in the gate pads
103
of the gate lines
101
and the data pads
104
of the data lines
102
. The shorting bars
106
and
107
are formed to prevent static electricity generated from the gate and data pads from being applied to the TFTs and thus destroying the TFTs. Also, the shorting bars are used at the time of testing.
Herein, the first shorting bar
106
of the gate line is connected to an odd gate line
101
a
and an even gate line
101
b
. the odd gate line
101
a
is later detached from the first shorting bar
106
by cutting a cutting region
108
.
As aforementioned, the first shorting bar
106
is connected to the odd gate line
101
a
and the even gate line
101
b
so as to examine an array of TFTs. The odd gate line has to be detached from the first shorting bar after examining the array of TFTs. The detached part is the cutting region.
FIG. 2
is an enlarged plane view of A in
FIG. 1
illustrating gate pads, odd and even gate lines concretely.
As shown in
FIG. 2
, the first and second shorting bars
106
and
107
are formed at vertical directions with the odd and even gate lines
101
a
and
101
b
. Herein, the first and second shorting bars
106
and
107
consist of materials which respectively form the gate lines and the data lines.
The odd gate line connected to the first shorting bar
106
has narrow line width between the first and second shorting bars
106
and
107
so as to facilitate cutting from the first shorting bar
106
.
FIGS. 3A
to
3
C are sectional views illustrating a related art method for patterning the pixel electrode of the active region and for a metal pattern process of the cutting region. For reference, the cutting region is a sectional view taken along line I—I′ of FIG.
2
.
As shown in
FIG. 3A
, a gate electrode material (AlNd or Al) is deposited on an insulating substrate
301
including an active region and a cutting region, and patterned to form gate lines (not shown, see
FIG. 1
) including a gate electrode
302
. At this time, a gate metal
302
a
for connecting gate pads of the cutting region and shorting bar are simultaneously formed.
A gate insulating film
303
is deposited on an entire surface of the substrate including the gate electrode
302
. Subsequently, a semiconductor layer
304
is formed on the gate insulating film
303
above the gate electrode
302
of the active region. Data lines (not shown, see
FIG. 1
) are sequentially formed at a vertical direction to the gate lines so that source and drain electrodes
305
and
306
of TFTs are placed on both sides of the semiconductor layer
304
.
A passivation film
307
is formed on an entire surface of the substrate of the active region and cutting region including the source and drain electrodes
305
and
306
. The passivation film is then selectively eliminated to expose a predetermined part of the drain electrode
306
of TFTs in the active region and to expose the gate metal
302
a
in the cutting region, thereby forming a contact hole. A transparent electrode
308
of ITO material is then deposited on an entire surface so as to electrically be connected to the drain electrode
306
of TFTs and the gate metal
302
a.
As shown in
FIG. 3B
, a photoresist
309
is deposited on an entire surface, and then patterned by exposure and developing processes so that only pixel region remains in the active region and the gate metal
302
a
is exposed in the cutting region.
Subsequently, as shown in
FIG. 3C
, the transparent electrode
308
is selectively eliminated in the active region by using the patterned photoresist
309
as a mask, thereby forming a pixel electrode
308
a
. Then, the transparent electrode
308
and the gate metal
302
a
exposed from the patterned photoresist
309
are simultaneously eliminated in the cutting region. At this time, an etchant based on HCL is used for etching to eliminate the transparent electrode
308
and the gate metal
302
a
at the same time in the cutting region.
Although not shown, the photoresist
309
is eliminated and an alignment film is deposited on an entire surface, thereby completing the lower substrate.
However, the related art method for fabricating the LCD device has the following problems.
FIG. 4
is a structural sectional view illustrating problems according to a related art method for fabricating the LCD device.
That is, as the etchant based on HCL is used for etching to the gate metal and the transparent electrode at the same time in the cutting region, conductive materials in the cutting region is cleanly eliminated. However, as shown in
FIG. 4
, strong erosion characteristic of the HCL causes crack of the passivation film of TFTs in the active region, and an etchant based on the HCL is penetrated into the crack so that galvanic effect is generated with the gate lines formed of AlNd or Al, thereby causing disconnecting among gate lines.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a method for fabricating thin film transistor-LCD that substantially obviates one or more problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a method for fabricating thin film transistor-a stable LCD by using two etching etchants in a process and then by eliminating the pixel electrode and the gate metal.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become
Jeong Beung Hwa
Lee Hyung Chan
Lee Youn Bo
Park Gi Bum
Song Ii Nam
Le Vu A.
LG.Philips LCD Co. , Ltd.
Luu Pho M.
Morgan & Lewis & Bockius, LLP
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