Semiconductor device manufacturing: process – Making field effect device having pair of active regions... – On insulating substrate or layer
Reexamination Certificate
2000-09-07
2003-07-29
Zaradian, Amir (Department: 2822)
Semiconductor device manufacturing: process
Making field effect device having pair of active regions...
On insulating substrate or layer
C438S030000, C438S048000, C438S149000
Reexamination Certificate
active
06599786
ABSTRACT:
CROSS REFERENCE
This application claims the benefit of Korean Patent Application No. 1999-0038016, filed on Sep. 8, 1999, under 35 U.S.C. §119, the entirety of 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 a method of fabricating the LCD device, and more particularly, to an array substrate having thin film transistors for the liquid crystal display device and the method of fabricating the array substrate.
2. Description of Related Art
Recently, according to a rapid development in a thin-film-transistor addressed liquid crystal display device (TFT/LCD, hereinafter noted simply as a liquid crystal display device), various portable electric appliances adopt the liquid crystal display device due to its advantage in a light weight and a wide applicability. Thus, an improved manufacturing process technology of the liquid crystal display device becomes required for a cheaper production cost and a higher productivity.
The liquid crystal display device manufacturing process requires repeated steps of depositing and patterning of various layers. The patterning step adopts a photolithography mask step including a light exposing with a mask. Since one cycle of the photolithography step is facilitated with one mask, the number of masks used in the fabrication process is a critical factor in determining the number of patterning steps. Namely, the production cost substantially depends on the number of masks used in the manufacturing process.
Now, referring to the attached drawings, a conventional array substrate of the liquid crystal display device manufactured by a conventional method is explained in detail. For convenience of explanation, the attached drawings of plan views do not illustrate insulating layers interposed between metal films, but the insulating layers are shown in the cross-sectional views.
In
FIGS. 1
,
2
A and
2
B, on a transparent insulating substrate
1
, a gate line
10
is horizontally formed with a data line
14
formed perpendicular to the gate line
10
. Near a cross point between the gate and data lines
10
and
14
, a portion of the gate line
10
is protruded as a gate electrode
10
a
, and, at one end of the gate line
10
, a gate pad
10
b
is positioned. Further, near the cross point between the gate and data lines
10
and
14
, a source electrode
14
a
is protruded from the data line
14
, and, spaced apart from the source electrode
14
a
, a drain electrode
16
is formed. Also at one end of the data line
14
, a data pad
14
b
is positioned.
Herein, in the same layer of the data line
14
, between the drain electrode
16
and the gate pad
10
b
, a capacitor electrode
18
of the same material as the data line
14
is formed in shape of an island. The capacitor electrode
18
overlaps a corresponding portion of the gate line
10
so that the capacitor electrode
18
makes a storage capacitor together with the corresponding overlapped portion of the gate line
10
.
FIGS. 2A and 2B
illustrate cross-sections taken along lines “A—A” and “B—B” of
FIG. 1
, respectively. As shown in
FIGS. 2A and 2B
, a conductive metal layer is deposited on a surface of the substrate
1
, and patterned with a first mask so as to form the gate line
10
including the gate electrode
10
a
and the gate pad
10
b.
On the whole surface including the gate lines of the substrate
1
, an insulating material, a semiconductor material, and a doped semiconductor material are sequentially deposited, and patterned with a second mask so as to form a first insulating layer
3
, a semiconductor layer
12
, and an ohmic contact layer
13
.
Next, another conductive metallic material is deposited on the whole surface including the ohmic contact layer
13
of the substrate
1
, and thereafter the metal layer and the ohmic contact layer
13
are patterned with a third mask so that the source, drain and capacitor electrodes
14
a
,
16
and
18
are formed. At this point, between the source and drain electrodes
14
a
and
16
, a back channel is opened so as to expose a portion of the semiconductor layer
12
.
FIGS. 3
,
4
A and
4
B illustrate a completed array substrate for the liquid crystal display device.
On the whole surface including the patterned metal layer of
FIG. 2
, a second insulating layer
7
shown in
FIGS. 4A and 4B
is deposited, and patterned with a fourth mask so as to form a first to a fourth contact holes
20
a
,
20
b
,
20
c
, and
20
d
. The first contact hole
20
a
exposes a portion of the data pad
14
b
; the second contact hole
20
b
exposes a portion of the capacitor electrode
18
; the third contact hole
20
c
exposes a portion of the gate pad
10
b
; and the fourth contact hole
20
d
exposes a portion of the drain electrode
16
. Via the data and gate pads
14
b
and
16
, an outer circuit transmits data and gate signals, respectively.
On the whole surface including the second insulating layer
7
, an indium tin oxide (ITO) layer is deposited and patterned so as to form a pixel electrode
24
and a data pad terminal
26
; the data pad terminal contacts with the data pad
14
b
through the first contact hole
20
a.
Further, a portion of the pixel electrode
24
is electrically connected with the capacitor electrode
18
through the second contact hole
20
b
; another portion of the pixel electrode
24
is electrically connected with the drain electrode
16
through the fourth contact hole
20
d.
At this point, the capacitor electrode
18
, electrically connected with the pixel electrode
24
through the second contact hole
20
b
of
FIG. 3
, plays a role of an electrode of the storage capacitor; the overlapped portion of the gate line
10
under the capacitor electrode
18
plays a role of the other electrode of the storage capacitor.
Since the above-described conventional method of manufacturing the array substrate of the liquid crystal display device employs too many masks, the method has a disadvantage of too many-repeated photolithography steps, which results in high production cost and inferiority percentage.
SUMMARY OF THE INVENTION
In view of the foregoing and other problems of the conventional manufacturing method of the liquid crystal display device, it is an object of the present invention to provide a relatively low cost manufacturing method of the array substrate for the liquid crystal display device.
It is another object of the present invention to provide an improved array substrate for the liquid crystal display device manufactured by the above-mentioned method.
To achieve the above-mentioned objects, the present invention provides a four-mask method of manufacturing an array substrate of a liquid crystal display device and an array substrate fabricated by the method. The method includes forming a plurality of gate lines, gate electrodes and gate extension lines by depositing a first metallic material on a substrate and patterning the first metallic material with a first mask, the gate extension lines extending toward the opposite direction of the gate electrodes; forming a first insulating layer on the whole surface having gate lines, gate electrodes, and gate extension lines; forming a plurality of data lines, source electrodes, drain electrodes, and capacitor electrodes over the gate lines by depositing a semiconductor layer, an ohmic contact layer and a second metallic material sequentially on the first insulating layer, and patterning the second metallic material and the ohmic contact layer with a second mask; forming a passivation layer and a plurality of first and second contact holes by depositing a second insulating layer on the data lines, the source electrodes, the drain electrodes and the capacitor electrodes, and patterning the second insulating layer with a third mask, the first contact holes exposing a portion of the drain electrode, the second contact holes exposing a portion of the capacitor electrodes; and forming a plurality of pixel electrodes by depositing a transparent conductive layer on the
Ahn Byung-chul
Kim Yong-wan
Lim Byoung-ho
Yoo Soon-sung
LG.Philips LCD Co. , Ltd.
McKenna Long & Aldridge LLP
Perkins Pamela E
Zaradian Amir
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