Semiconductor device manufacturing: process – Making device or circuit emissive of nonelectrical signal – Including integrally formed optical element
Reexamination Certificate
2000-12-07
2001-10-30
Booth, Richard (Department: 2812)
Semiconductor device manufacturing: process
Making device or circuit emissive of nonelectrical signal
Including integrally formed optical element
C438S158000
Reexamination Certificate
active
06309903
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for manufacturing a fringe field switching mode liquid crystal display device, and in particular to an improved method for manufacturing a fringe field switching mode liquid crystal display device which can reduce steps of the manufacturing process.
2. Description of the Background Art
A fringe field switching mode liquid crystal display device (high aperture ratio and transmissibility liquid crystal display device) has been suggested to improve a low aperture ratio and transmissibility of a general IPS mode liquid crystal display device, and filed in Korea under Application No. 98-9243.
In the fringe field switching mode liquid crystal display device, a counter electrode and a pixel electrode consist of a transparent conductive material. An interval between the counter electrode and the pixel electrode is narrower than an interval between upper and lower substrates. A fringe field is formed at the upper portions of the counter electrode and the pixel electrode.
A conventional method for manufacturing a fringe field switching mode liquid crystal display device will now be described with reference to FIG.
1
.
As illustrated in
FIG. 1
, an indium tin oxide (ITO) layer is formed at the upper portion of a lower transparent insulating substrate
1
according to a sputtering method, by using Ar gas, O
2
gas and ITO gas. The ITO layer is patterned to have a comb or plate shape, thereby forming a counter electrode
2
(first mask process).
Thereafter, an opaque metal film is formed according to the sputtering method at the upper portion of the lower substrate
1
where the counter electrode
2
has been formed. A gate bus line
3
and a common electrode line (not shown) are formed by patterning a predetermined portion of the opaque metal film (second mask process).
A gate insulating film
4
, an amorphous silicon layer
5
for a channel and a doped amorphous silicon layer
6
are stacked at the upper portion of the transparent insulating film
1
where the gate bus line
3
has been formed, and patterned to have a thin film transistor shape (third mask process).
An ITO layer is deposited over the resultant structure according to the sputtering method, and patterned on the counter electrode
2
to have a comb shape, thereby forming a pixel electrode
7
(fourth mask process).
A pad is opened by removing the gate insulating film on a gate pad unit (fifth mask process).
Thereafter, an opaque metal film is deposited over the resultant structure according to the sputtering method. A source electrode
8
a
, a drain electrode
8
b
and a data bus line (not shown) are formed by etching a predetermined portion of the opaque metal film (sixth mask process). The exposed doped amorphous silicon layer
7
is removed according to a publicly known method. Here, the opened gate pad unit and a metal film for a data bus line are contacted.
However, as described above, the conventional method requires six mask processes for forming a lower substrate structure of the fringe field switching mode liquid crystal display device.
Here, the mask process is a photography including a resist spreading process, an exposure process, a developing process, an etching process and a resist removing process. Accordingly, it takes a long time to carry out one mask process.
As a result, a manufacturing time and cost of the fringe field switching mode liquid crystal display device are remarkably increased, and thus a yield thereof is reduced.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a method for manufacturing a fringe field switching mode liquid crystal display device which can improve productivity by reducing steps of a manufacturing process.
In order to achieve the above-described object of the present invention, there is provided a method for manufacturing a fringe field switching mode liquid crystal display device, including the steps of: forming a gate bus line, a counter electrode structure and a gate pad at an edge of a lower substrate, by sequentially stacking a transparent conductive layer and an opaque metal film on the lower substrate, and patterning a predetermined portion thereof; forming an active region by sequentially stacking a gate insulating film, an amorphous silicon layer for a channel and a doped amorphous silicon layer at the upper portion of the lower substrate where the gate bus line and the counter electrode structure have been formed, and patterning the doped amorphous silicon layer and the amorphous silicon layer for the channel to cover the gate bus line; forming a counter electrode by removing the opaque metal film on the exposed counter electrode structure; depositing an insulating film on the resultant structure of the lower substrate; forming a pixel electrode by forming a transparent conductive layer on the insulating film, and patterning the transparent conductive layer in a comb shape to be overlapped with the counter electrode; etching the insulating film to open the gate pad, and simultaneously etching the insulating film in the active region; and forming a data bus line, a source electrode and a drain electrode, by depositing an opaque metal film on the resultant structure of the lower substrate, and patterning the opaque metal film to cross the gate bus line and exist at both sides of the active region, wherein a fringe field being generated when the pixel electrode and the counter electrode have a voltage difference.
Here, the transparent conductive layer is an indium tin oxide (ITO) layer, the opaque metal film for the gate bus line is selected from the group consisting of Mo, Cr, Al and MoW, and the opaque metal film for the data bus line is selected from the group consisting of Mo, Al and Mo/Al/Mo.
According to the present invention, the gate bus line has a stacked structure of the transparent metal layer and the opaque metal layer. In the formation of the gate bus line, the counter electrode structure is firstly formed, and the active region is formed to cover the gate bus line. Thereafter, the counter electrode is formed by removing the opaque metal layer on the exposed surface of the counter electrode structure. Therefore, the gate bus line and the counter electrode structure are formed at the same time, thereby reducing one mask process. As a result, the fringe field switching mode liquid crystal display device can be manufactured by five mask processes.
REFERENCES:
patent: 2332769-A (1999-06-01), None
Cho Sung Hyun
Shin Jae Hak
Booth Richard
Hyundai Electronics Industries Co,. Ltd.
Ladas & Parry
Roman Angel
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