Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2000-12-15
2004-08-03
Ton, Toan (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S152000, C349S043000, C349S140000
Reexamination Certificate
active
06771346
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a liquid crystal display which drives the liquid crystal by using an active matrix substrate on which a thin-film transistor (hereinafter, referred to TFT (Thin Film Transistor) is formed, and also concerns a manufacturing method for such a liquid crystal display.
BACKGROUND OF THE INVENTION
As illustrated in
FIG. 14
, in a conventional liquid crystal display using a TFT as a switching element, on a glass substrate
101
are placed a gate electrode
102
formed through the same process, gate wiring (not shown) connected to the gate electrode
102
and a source signal input terminal
103
.
Moreover, a gate insulation film
105
is formed on the entire surface of the glass substrate
101
, except for a terminal section contact hole
104
formed on the source signal input terminal
103
. On the gate electrode
102
are placed, through a gate insulation film
105
, an amorphous silicon semiconductor layer (hereinafter, referred to as a-Si layer)
106
and an amorphous silicon semiconductor layer (hereinafter referred to as n
+
a-Si layer)
107
. The n
+
a-Si layer
107
, which is an amorphous silicon semiconductor layer to which an impurity is added, is an ohmic contact layer that is provided so as to ohmic-connect the a-Si layer
106
to a source electrode and a drain electrode, which will be described later.
A source electrode
108
and a drain electrode
109
are placed on the a-Si layer
106
and n
+
a-Si layer
107
, and a source wire
110
is formed integrally with the source electrode
108
through the same process.
A TFT
111
is constituted by the gate electrode
102
, a-Si layer
106
, n
+
a-Si layer
107
, source electrode
108
, and drain electrode
109
, etc., arranged as described above.
Moreover, a protective film
113
and a resin layer
114
, which are used for protecting one portion of the source wire
110
and the TFT
111
, are formed except for the terminal section contact hole
104
and a display section contact hole
112
formed on the drain electrode
109
.
Moreover, the connection electrode
115
is joined to the source signal input terminal
103
so that the source wire
110
and the source signal input terminal
103
are connected to each other through the terminal contact hole
104
. Moreover, the display electrode layer
116
and the drain electrode
109
are connected through the display contact hole
112
.
The above-mentioned conventional liquid crystal display is manufactured through the following processes (1) to (8):
(1) First, a metal thin film, composed of titanium (Ti), aluminum (Al), or chromium (Cr), etc., is formed on a washed glass substrate
101
by sputtering, etc. Then, a photolithographic technique, which carries out etching by using a mask that is formed by applying photoresist to the metal thin film and exposing and developing it, is used to simultaneously form the gate electrode
102
, the gate wire connected to the gate electrode
102
and the source signal input terminal
103
.
(2) SiN
x
, which forms a gate insulation film
105
, is formed thereon by using a mixed gas of SiH
4
/NH
3
/N
2
through a P-CVD method.
(3) an a-Si film is formed on the gate insulation film
105
by using SiH
4
/H
2
.gas through a P-CVD method. In the same manner, an n
+
a-Si film is formed by using SiH
4
/H
2
.gas with mixed PH
3
through a P-CVD method. Thereafter, the a-Si layer
106
and the n
+
a-Si layer
107
are patterned through a photolithography technique, etc.
(4) Moreover, a multi-layer structure metal thin-film, such as an Al/Ti thin-film, is formed, and this metal thin film is patterned through a photolithography technique, etc.
so that a source electrode
108
, a drain electrode
109
and a source wire
110
are formed.
(5) Next, SiN
x
is deposited by a P-CVD method using a mixed gas of SiH
4
/NH
3
/N
2
to form a protective film
113
.
(6) On the protective film
113
, a resin layer
114
, which serves as a second protective film, is patterned and formed through a photolithography method, etc., and is subjected to a heating process, etc. to cure the resin. In this state, terminal section contact holes
104
and display section contact holes
112
are formed in the resin layer
114
.
(7) Next, in the terminal section contact hole
104
, the gate insulation film
105
and the protective film
113
are simultaneously etched and removed by using the source wire
110
and the resin layer
114
as masks. Here, with respect to the display section contact hole
112
formed in the process (6), since the drain electrode
109
serves as an etching stopper, the gate insulation film
105
beneath it is allowed to remain.
(8) The connection electrode
115
and the display electrode
116
are formed.
Moreover, as illustrated in
FIG. 15
(
a
) and FIG.
15
(
b
), in another liquid crystal display, on an insulation substrate
201
made of glass, etc., a gate wire
202
on which a gate signal input terminal
202
a
and a gate electrode
202
b
are integrally formed, a support capacity wire
204
, a support capacity electrode
204
b
and support capacity signal input terminal
204
a
connected to the support capacity wire
204
are formed.
Then, on top of these layers, through a gate insulation film
207
, are formed an a-Si layer
208
a
made of an amorphous silicon semiconductor layer, and an n
+
a-Si layer
208
b
that is an amorphous silicon semiconductor layer to which impurities such as phosphor (P) are added so as to realize ohmic connections between the a-Si layer
208
a
and a source electrode
209
b
as well as a drain electrode
210
.
Next, after a multi-layer structure film, such as an Al/Ti film, not shown, has been deposited on the a-Si layer
208
a
and n
+
a-Si layer
208
b
that are the semiconductors, a source electrode
209
b
, a drain electrode
210
and a source wire
209
that serves as bus wiring for them are formed. Moreover, a TFT
211
is formed by the source wire
209
, a source electrode
209
b
and a source signal input terminal
209
c
that are integral with the source wire
209
and a drain electrode
210
.
Next, an overcoat layer
212
, made of an insulation film such as SIN, for protecting the source wire
209
and TET
211
, and a resin insulation film
213
made of an insulation photosensitive acrylic resin, etc. are successively laminated so that an overcoat layer having a two-layer structure is formed.
Next, the resin insulation film
213
, made of a photosensitive acrylic resin, etc., is exposed in an exposing process by using a predetermined mask, and then subjected to a developing process so that a contact hole
215
is formed in the resin insulation film
213
. Simultaneously with this process, the resin insulation film
213
over the source signal input terminal
209
c
, the gate signal input terminal
202
a
and support capacitor signal input terminal
204
a
is removed therefrom.
By using the resin insulation film
213
thus patterned as a mask for an etching process, the overcoat layer
212
located at the bottom of the contact hole
215
, and the overcoat layer
212
covering the source signal input terminal
209
c
, the gate signal input terminal
202
a
and the supplementary capacitance signal input terminal
204
a
are simultaneously removed.
Successively, by using the resin insulation film
213
patterned as described above as a mask for an etching process, the gate insulation film
207
covering the gate signal input terminal
202
a
and the supplementary capacitance signal input terminal
204
a
is removed therefrom.
Next, a pixel display electrode
214
, which is used for applying a voltage to liquid crystal formed over the surface of the resin insulation film
213
including the inside of the contact hole
215
formed in the resin insulation film
213
, is formed so that the drain electrode
210
on the base section of the contact hole
215
is electrically connected.
However, the above-mentioned manufacturing method for the conventional liquid crystal display has raised the following problems.
In the
Imai Hajime
Sugimoto Osamu
Conlin David G.
Duong Thoi V.
Edwards & Angell LLP
Konieczny J. Mark
Sharp Kabushiki Kaisha
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