Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2000-08-04
2004-01-27
Ngo, Julie (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S152000, C349S153000
Reexamination Certificate
active
06683669
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a substrate and a liquid crystal display (LCD) device, and particularly relates to a wire structure of the same and a method for fabricating the same.
BACKGROUND OF THE INVENTION
Recently liquid crystal display (LCD) devices having greater display capacities and higher image quality have been demanded, and LCD devices of active matrix driving type in which switching elements are respectively provided for pixels constituting display screens have been developed in response to the foregoing demand. For example, as the foregoing switching elements, thin film transistor (TFT) elements and metal-insulator-metal (MIM) elements have been turned to practical use.
FIG. 9
illustrates a structure of a liquid crystal cell using MIM elements.
Generally, the liquid crystal cell has a structure consisting of an element substrate
1
and a counter substrate
2
that are made to adhere to each other with a sealing material
16
, and liquid crystal is sealed inside to the sealing material
16
. Furthermore, to arrange a desired optical system, an optical film such as, for example, a polarizing plate
17
is applied on at least a surface side of the liquid crystal cell.
Furthermore, as shown in
FIG. 10
, each pixel on the element substrate
1
is composed of a signal wire
3
, a MIM element
4
, and a pixel electrode
6
. The MIM element
4
is composed of a lower electrode
3
a
, a thin insulator
9
(see FIG.
11
(
b
)) formed so as to cover the lower electrode
3
a
, and an upper electrode
5
, so as to be formed at an intersection of the lower electrode
3
a
and th e upper electrode
5
.
As shown in
FIG. 9
, to apply signals to the pixels, element-side terminal electrodes
10
are provided on the same surface of the element substrate
1
on that the signal wires
3
(see FIG.
11
(
a
)) are provided, and connection wires
7
are formed so as to connect the signal wires
3
with the element-side terminal electrodes
10
. On the counter substrate
2
, there are provided counter-side electrodes
14
as well as counter-side terminal electrodes
12
and connection wires
13
for applying signals to the counter-side electrodes
14
.
Display of images is carried out by connecting driving-use circuit members
11
and
15
with the element-side terminal electrodes
10
on the element substrate
1
and the counter-side terminal electrodes
12
on the counter substrate
2
, and by applying predetermined signals thereto.
The following description will explain a common method for fabricating the element substrate
1
using such MIM elements
4
, while referring to FIGS.
11
(
a
) through
11
(
d
).
First of all, as shown in FIG.
11
(
a
), a first conductive material is laminated on a glass substrate by sputtering or the like, and it is patterned to predetermined shapes by photolithography, so that the signal wires
3
, the lower electrodes
3
a
, the connection wires
7
, and the element-side terminals
8
should be formed.
Next, as shown in FIG.
11
(
b
), thin insulators
9
are provided at least on surfaces of the lower electrodes
3
a
. Generally, to form the insulators
9
, a method of soaking the element substrate
1
into electrolytic liquid and applying a voltage thereto, that is, so-called anodization, is applied. If upon the anodization the insulators
9
are provided over the element-side terminal electrodes
10
, it should be inconvenient, since conduction will not be provided between the element-side terminal electrodes
10
and the circuit member
11
at later stages. Therefore, the following process is applied: the element-side terminal electrodes
8
are covered with protective films such as resin beforehand, and anodization is applied thereto in this state, then, the protective films are removed.
Further, as shown in FIG.
11
(
c
), a second conductive material that will be later formed into the upper electrodes
5
composing the MIM elements
4
is laminated by sputtering or-the like, and thereafter it is patterned to predetermined shapes by photolithography.
Finally, as shown in FIG.
11
(
d
), a third conductive material that will be later formed into the pixel electrodes
6
is laminated by sputtering or the like, and thereafter it is patterned to predetermined shapes by photolithography. Incidentally, to ensure reliability of electric connection between the circuit member
11
and the element-side terminals
8
, the element-side terminal electrodes
10
are sometimes provided to the element-side terminals
8
.
FIGS.
12
(
a
) through
12
(
d
) illustrates another method for fabricating the element substrate
1
.
First, as shown in FIG.
12
(
a
), the first conductive material is laminated on a glass substrate by sputtering or the like, and it is patterned to predetermined shapes by photolithography, so that the signal wires
3
, the lower electrodes
3
a
, the connection wires
7
, and the element-side terminals
8
should be formed.
Next, as shown in FIG.
12
(
b
), the thin insulators
9
are provided on an entirety of surfaces of the first conductive material by anodization, and through holes
18
are formed by patterning the insulators
9
covering surface of the element-side terminals
8
, so that the first conductive material should be exposed through the through holes
18
.
Further, as shown in FIG.
12
(
c
), the second conductive material that will be later formed into the upper electrodes
5
composing the MIM elements
4
is laminated by sputtering or the like, and thereafter it is patterned to predetermined shapes by photolithography.
Finally, as shown in FIG.
12
(
d
), the third conductive material that will be later formed into the pixel electrodes
6
is laminated by sputtering or the like, and thereafter, it is patterned to predetermined shapes by photolithography. Incidentally, to ensure reliability of electric connection between the circuit member
11
and the element-side terminals
8
, the element-side terminal electrodes
10
are sometimes provided to the element-side terminals
8
, like the aforementioned fabrication method.
By either of the foregoing fabrication methods, the insulators
9
that are uniform can be formed since the substrate is not soiled with resin and the like before anodization. Therefore, the foregoing fabrication methods can provide an advantage that the MIM elements
4
having less differences in characteristics can be obtained.
On the other hand, the counter substrate
2
is more easily formed than the element substrate
1
is. For example, after an electrode material is laminated on a glass substrate by sputtering or the like, the counter-side terminal electrodes
12
, the connection wires
13
, and the counter-side electrodes
14
are simultaneously formed by patterning, whereby the counter substrate
2
is obtained.
Furthermore, the counter substrate
2
occasion ally does not require so fine wiring processing as the element substrate
1
does, and in such a case, patterning of the counter-side terminal electrodes
12
, the connection wires
13
, and the counter-side electrodes
14
is realized by sputtering of an electrode material with use of deposition masks.
On electrode film surfaces of display areas of the element substrate
1
and the counter substrate
2
thus formed, an alignment film (not shown) is provided. After applying a rubbing operation thereto, the substrates
1
and
2
are combined in a manner such that the electrodes face each other, and is made to adhere to each other with a sealing material
16
. Through an opening (not shown) provided at a certain position, liquid crystal is injected by vacuum injection or the like, and is sealed. Thereafter, an optical film such as a polarizing plate
17
is applied over a display surface of the liquid crystal cell, and the circuit member
11
is attached. Thus, an LCD device is completed.
Generally, a liquid crystal cell is fabricated by fabricating a large-size mother glass equivalent to a plurality of liquid crystal cells and by cutting out each liquid crystal cell from the mother glass. Therefore, in the case wher
Ngo Julie
Sharp Kabushiki Kaisha
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