Radiation imagery chemistry: process – composition – or product th – Radiation modifying product or process of making – Radiation mask
Reexamination Certificate
2000-06-22
2002-05-21
Rosasco, S. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Radiation modifying product or process of making
Radiation mask
Reexamination Certificate
active
06391499
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a light exposure mask and a method of manufacturing the same, and more particularly, to a light exposure mask and a method of manufacturing the same for use in a liquid crystal display (LCD) device.
2. Description of Related Art
FIG. 1
is a plan view illustrating a typical LCD device. As shown in
FIG. 1
, the typical LCD device comprises gate lines
60
arranged in a transverse direction, data lines
70
arranged in a longitudinal direction perpendicular to the gate lines
60
, thin film transistors (TFTs) “S” located near cross points of the gate lines
60
and the data lines
70
, and pixel regions
40
defined by the gate lines
60
and the data lines
70
.
The typical LCD device is manufactured by the following processes.
FIG. 2
is a cross-sectional view taken along line ∥—∥ of FIG.
1
. First, a gate electrode
60
a
is formed on a transparent substrate
10
, and then a gate insulating layer
50
made of a inorganic material such as SiNx or SiOx is formed on the whole surface of the transparent substrate
10
while covering the gate electrode
60
a.
The gate electrode
60
a
contacts the gate line
60
. Sequentially, a semiconductor layer
80
is formed over the gate electrode
60
a
in the form of an island. The semiconductor layer
80
has an amorphous silicon layer
80
a
and a doped amorphous silicon layer
80
b.
Source and drain electrodes
70
a
and
70
b
spaced apart from each other are formed overlapping a region of both ends of the doped amorphous silicon layer
80
b.
The source electrode
70
a
contacts the data line
70
, and the drain electrode
70
b
contacts a pixel electrode that is formed in a subsequent process. Then, a passivation layer
55
is formed on the whole surface of the transparent substrate
10
covering the source and drain electrodes
70
a
and
70
b,
and then a contact hole
42
is formed at a predetermined location over the drain electrode
70
b.
The pixel electrode
44
is formed on the pixel region
40
to contact the drain electrode
70
b
through the contact hole
42
.
Most components of the typical LCD device described above are formed using several photolithography processes. In the conventional photolithography process, as shown in
FIG. 3A
, a metal layer
90
is formed on the substrate
10
. Either a positive or a negative photoresist is applied on the metal layer
90
, and then a light exposure mask
88
is aligned.
FIG. 3A
shows the positive photoresist
100
, and the light exposure mask
88
has light transmitting regions
88
a,
88
c
and a light shielding region
88
b.
Sequentially, when UV light is irradiated toward the light exposure mask
88
, the photoresist
100
is developed, thereby forming a photoresist pattern
10
a
shown in FIG.
3
B.
Then, the photoresist pattern
10
a
is subjected to a predetermined temperature and atmosphere to become hardened. The metal layer
90
is etched according to the photoresist pattern
100
a
using either of a dry etching technique or a wet etching technique so that a metal pattern layer
90
a
is formed as shown in FIG.
3
C. Finally, the photoresist patter
100
a
remaining on the metal pattern layer
90
a
is removed.
However, when using the conventional light exposure mask
88
described above, since the light transmitting regions
88
a,
88
c
and the light shielding region
88
b
of the light exposure mask
88
transmits and shields the UV light perfectly, respectively, the metal pattern layer
90
a
formed comes to have an almost rectangular-shaped cross section. Therefore, when another metal layer (not shown) is formed on the rectangular-shaped metal pattern layer
90
a,
there arises a problem in that step coverage becomes degraded so that an open line may occur at a step portion.
FIGS. 4A through 4C
show another photolithography process to form a dual-layered metal pattern layer. As shown in
FIG. 4A
, first and second metal layers
90
and
91
are sequentially formed on a transparent substrate
10
, and a positive photoresist
100
is applied on the second metal layer
91
. Then, a light exposure mask
88
having a light transmitting region
80
a
and a light shielding region
80
b
is aligned. Sequentially, when UV light is irradiated toward the light exposure mask
88
, the photoresist
100
is developed, thereby forming a photoresist pattern
100
a
as shown in FIG.
4
B.
Then, the photoresist pattern
100
a
is subjected to a predetermined temperature and atmosphere to become hardened. The first and second metal layers
90
and
91
are simultaneously etched according to the photoresist pattern
100
a
using either of a dry etching technique or a wet etching technique so that first and second metal pattern layers
90
a
and
91
a
are formed, as shown in FIG.
4
C. Finally, the photoresist pattern
100
a
remaining on the second metal pattern layer
91
a
is removed.
However, when using the conventional light exposure mask
88
described above, the metal pattern layers
90
and
91
inevitably have the same shape, thus, in order to form different shaped metal layers, an additional photolithography process should be performed again, leading to a lengthy processing time and a low yield.
SUMMARY OF THE INVENTION
To overcome the problems described above, preferred embodiments of the present invention provide a light exposure mask having a substrate defined by the following three regions: a light transmitting region, a light shielding region and a light semi-transmitting region.
Another embodiment of the invention provides a method for manufacturing a light exposure mask having a light transmitting region, a light shielding region, and a semi-transmitting region, comprising the steps of: preparing a transparent substrate; forming a semi-transmitting layer and a light shielding layer on the substrate in this order; patterning the light shielding layer to define the light shielding region of the substrate; and patterning the semi-transmitting layer so that the semi-transmitting region of the substrate is covered by the patterned semi-transmitting layer.
The light shielding layer preferably has Cr/CrOx, and the semi-transmitting layer preferably has indium tin oxide.
Another embodiment of the invention provides a method for manufacturing a light exposure mask having a light transmitting region, a light shielding region, and a semi-transmitting region, comprising the steps of: preparing a transparent substrate; forming a light shielding layer on the substrate; patterning the light shielding layer to define the light shielding region of the substrate; forming a semi-transmitting layer on the substrate while covering the patterned light shielding layer; and patterning the semi-transmitting layer so that the semi-transmitting region of the substrate is covered by the patterned semi-transmitting layer.
REFERENCES:
patent: 4415262 (1983-11-01), Koyama et al.
patent: 5614335 (1997-03-01), Hashimoto et al.
patent: 5936707 (1999-08-01), Nguyen et al.
patent: H2-299125 (1990-12-01), None
Abstract: Japan patent publication No. H2-299125; dated Dec. 11, 1990; Title: “Electrode Forming Method and Electron Wire Display Device”.
Kim Jong-Woo
Kim Yong-Wan
Birch & Stewart Kolasch & Birch, LLP
LG Philips LCD Co., Ltd.
Rosasco S.
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