JPH05281574A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To reduce defective insulation and structural defects so as to improve reliability by interposing a liquid crystal between a drive base and an opposed base, and forming a storage capacity electrode on the uppermost layer of the drive base, around each picture element electrode through an insulating film. CONSTITUTION:Plural picture element electrodes 2-1-2-n formed of transparent conductive material and thin film transistors 3-1-3-n adjacent to the picture element electrodes are provided on a glass base 1 to form a drive base A. A storage capacity electrode 7 made of light intercepting conductive material formed of single metal such as chrome or an alloy of two kinds of metal or more is formed at the uppermost layer of the drive base A, integrally across the whole face around the respective picture element electrodes 2-1-2-n through an insulating film 6b. An opposed electrode 8 is formed of transparent conductive material formed on the whole surface of a glass base 9. The glass base 1 and glass base 9 are held to the specified spacing by insulating and conductive spacers, and a liquid crystal 10 is filled into this clearance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device in which a thin film transistor controls switching of an applied voltage to a liquid crystal for display.

In recent years, display devices using liquid crystals have been required to have high resolution.

In order to improve the resolution, it is necessary to make the pixel electrode small.

However, if the pixel electrode is made smaller, the capacitance due to the pixel electrode is reduced, so it is necessary to add a storage capacitor to compensate for this.

[0005]

2. Description of the Related Art FIG. 5 is a block diagram showing an example of a liquid crystal display device. In the figure, 12 is a drive substrate and 13 is a counter substrate.

Liquid crystal 14 is injected between the drive substrate 12 and the counter substrate 13.

A plurality of pixel electrodes 15 _-1 are formed on the driving substrate 12.
.About.15- _n are arranged in a matrix.

[0008] are each thin film transistor 16 _-1 ~ 16 _-n are formed adjacent to each pixel electrode 15 _-1 to 15 _-n.

The thin film transistors 16 _{-1 to} 16 _-n have gates connected to gate bus lines 17 _{-1 to} 17 _-m , drains connected to drain bus lines 18 _-1 to 18 _-l, and sources connected to pixel electrodes 15 _-1 to 15. 15- _n .

[0010] In certain of the thin film transistor is turned on among the thin film transistors 16 _-1 ~ 16 _-n in accordance with the signal supplied to the gate bus line 17 _-1 to 17 _-m and the drain bus line 18 _-1 ~ 18 _-l, A potential is applied to a predetermined pixel electrode among the pixel electrodes 15 _-1 to 15 _-n .

The counter substrate 13 has a structure in which a transparent electrode 20 is formed on the entire surface of a glass plate 19, and a constant potential is applied to the transparent electrode 20.

In the liquid crystal display device, a potential is applied to a predetermined pixel electrode to apply a voltage to the liquid crystal between the transparent electrode 20 and the predetermined pixel electrode, thereby changing the state of the liquid crystal in that portion to display an image. Are in control.

FIG. 6 shows a sectional view of a conventional example. First, the drive substrate 12 is formed on the glass substrate 21 by an IT for forming a storage capacitor.
A storage capacitor electrode 22 made of a transparent conductive material such as an O (Indium-Tin-Oxide) film is formed on the entire surface, an insulating film is formed on the storage capacitor electrode 22, pixel electrodes 15 _-1 to 15 _-n , and a thin film transistor 16 _-1.
˜16 _−n , gate bus lines 17 _{−1 to} 17 _−m , and drain bus lines 18 ₋₁ to 18 _−l were formed on the insulating film 23.

The storage capacitor electrode 22 is made to have the same potential as the counter electrode 20 to reduce the capacitance of the pixel electrodes 15 _-1 to 15 _-n .

[0015]

However, in the conventional liquid crystal display device, the thin film transistor, the gate bus line, and the drain bus line are formed in an uneven shape by the storage capacitor electrode and the insulating film on the storage capacitor electrode. A gate bus line, a drain bus line, etc. cannot be stably formed, and for example, deterioration of the breakdown voltage of a thin film transistor, a local occurrence caused by an insulating film between Al of the gate bus line or drain bus line and ITO of a storage capacitor electrode. Insulation defects and structural defects occur due to the battery effect,
There is a problem that the reliability of the liquid crystal display device is deteriorated.

The present invention has been made in view of the above points, and an object thereof is to provide a highly reliable liquid crystal display device in which insulation defects and structural defects are reduced.

[0017]

According to the present invention, there is provided a driving substrate having a predetermined number of pixel electrodes formed on a transparent substrate and a thin film transistor adjacent to the pixel electrodes, and a counter electrode facing the driving substrate. In a liquid crystal display device for displaying by changing the state of the liquid crystal by applying a voltage between the pixel electrode and the counter electrode by interposing a liquid crystal between the counter substrate on which the liquid crystal is formed. And a storage capacitor electrode formed around each pixel electrode via an insulating film.

[0018]

Since the storage capacitor electrode is laminated on the thin film transistor via the insulating film, the thin film transistor can be directly formed on the transparent substrate (1).

Therefore, since the thin film transistor can be formed on a flat substrate, a thin film transistor having stable characteristics can be obtained.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view of an essential part of an embodiment of the present invention, FIG. 2 is a sectional view of another essential part of an embodiment of the present invention, FIG.
FIG. 3 is a plan view of a main part of an embodiment of the present invention. In the figure, A
Is a drive substrate, and B is a counter substrate. Reference numeral 1 denotes a glass substrate which is a transparent substrate.

A plurality of pixel electrodes 2 are provided on the glass substrate 1._-1~
Two_-nAre formed in a matrix. Multiple pixel electrodes 2_-1
~ 2_-nIs a transparent conductive material such as ITO (Indium-Tin-Oxide)
Consists of. Three_-1~ 3_-nIs a thin film transistor (TFT)
Then, the thin film transistor 3_-1~ 3 _-nIs the gate electrode 3 respectively
a, drain electrode 3b, source electrode 3c, semiconductor layer 3d
Consists of a plurality of pixel electrodes 2_-1~ 2_-nAdjacent to each
Has been.

The gate electrode 3a is connected to a gate bus line 4 (FIG. 3) arranged between a plurality of pixel electrodes 2 _-1 to 2 _-n arranged in a matrix. Further, the drain electrode 3b is composed of a plurality of pixel electrodes 2 _-1 to 2 _-1 arranged in a matrix.
It is connected to the gate bus line 4 and the drain bus line 5 (FIG. 3) orthogonal to the insulation state between 2 and _n . The source electrode 3c is connected to the adjacent pixel electrodes 2 _-1 to 2 _-n .

A storage capacitor electrode 7 is formed on the thin film transistors 3 _{-1 to} 3 _{-n, the} gate bus line 4 and the drain bus line 5 via a protective film 6.

The storage capacitor electrode 7 is made of chromium (Cr), titanium (Ti), molybdenum (Mo), tantalum (Ta), cobalt (Co), niobium (Nb), tungsten (W), iridium (Ir), aluminum ( Al),
The light-shielding conductive material is a single metal such as nickel (Ni) or an alloy of two or more kinds. The storage capacitor electrode 7 is integrally formed over the entire surface.

The counter electrode 8 is an ITO (In
A transparent conductive material such as dium-tin-oxide) is formed on the entire surface of the glass substrate 9. The glass substrate 9 is arranged parallel to the glass substrate 1.

The glass substrate 1 and the glass substrate 9 are insulative spacers (not shown) and conductive spacers 11 (FIG. 2).
The liquid crystal 10 is held at a predetermined interval by the above, and the liquid crystal 10 is sealed in the space between the glass substrate 1 and the glass substrate 9.

One of the spacers for holding the space between the glass substrate 1 and the glass substrate 9 is composed of a conductive spacer 11 as shown in FIG. The conductive spacer 11 is the counter electrode 8
And the storage capacitor electrode 7 are connected. Therefore, the counter electrode 8 and the storage capacitor electrode 7 have the same potential.

FIG. 4 shows a manufacturing process diagram of an embodiment of the present invention. A manufacturing method according to an embodiment of the present invention will be described with reference to FIG.

First, the glass substrate 1 is provided with a parallel-moving substrate type counter target type McNetron sputter electrode,
The substrate temperature is set to 250 [℃] and the atmospheric pressure is set to about 0.005 by setting the substrate temperature to 250 [℃].
In the argon (Ar) gas atmosphere of [torr], Ti (800) is applied to the glass substrate 1 by targeting titanium (Ti).
[Å] Next, Al is formed on the glass substrate 1 by 1000 [Å] using aluminum (Al) as a target. A resist film pattern for the gate bus line 4 is formed on this film.

Using this resist film as a mask, aluminum is etched with a phosphoric acid type etchant. After this, BCl
Reactive ion etching is performed with a mixed gas of ₃ + Cl ₂ to etch the Ti film, and the gate electrode 3a and the gate bus line 4 are formed as shown in FIG. Subsequently, the resist is peeled off, the resist film is patterned so as to cover portions other than the intersections of the gate bus lines 4 (FIG. 3) and the drain bus lines 5 (FIG. 3), and aluminum is etched with a phosphoric acid-based etchant. Then, the resist is peeled off, and the gate bus line 4 and the drain bus line 5 are removed.
The pattern of (FIG. 3) is completed.

Then, a SiO ₂ film, a SiN film, and a gate insulating film 6a are formed by a P-CVD (plasma CVD) method.
An amorphous silicon film is continuously formed as the operating semiconductor film 3d, and a SiN film is continuously formed as the protective film 6b.

Next, a resist film is formed on the gate insulating film 6a. This resist film has a gap of several microns with the gate bus line 4, and is patterned by self-alignment so as to overlap the gate electrode 3a.

Using this resist as a mask, in the atmosphere of PH ₃ -doped SiH ₄ (silane), P--C
An n + a-Si film to be the semiconductor film 3d is formed by the VD method, and then Ti and Al are formed by the sputtering method.

The resist is dissolved with acetone or the like to lift off the n-type a-Si, Ti, and Al above the gate electrode 3a.

Next, the source electrode 3c and the drain electrode 3
The resist film for forming d is patterned, and this is used as a mask
As an etchant using a phosphoric acid-based etchant to remove Ti from B
Cl ₃+ Cl₂Reactive ion etch in the atmosphere
And the source electrode 3c as shown in FIG. 4 (B).
And the drain electrode 3d are formed. After performing this step
However, the SiN film of the gate insulating film 6a remains on the entire surface.
Become.

Next, the pixel electrodes 2 _-1 to 2 _-m made of an ITO film are formed in contact with the drain electrode 3c as shown in FIG. 4C.

Next, as shown in FIG. 4D, a SiN film to be the protective film 6b is formed.

After that, Al is mask-deposited only in the pixel portion. Pattern the resist so that it has openings in the pixel electrodes 2 _{-1 to} 2 _-n , and etch it with a phosphoric acid-based etchant.
The storage capacitor electrode 7 is formed as shown in FIG.
After that, an alignment film (not shown) is formed on the entire surface, and the alignment film is rubbed to complete the driving substrate.

On the other hand, an ITO film is formed on the entire surface of the glass substrate to form a counter substrate B, and then an alignment film (not shown) is formed on the entire surface, and the alignment film is rubbed. next,
The counter substrate B and the drive substrate A are opposed to each other, the ITO film of the counter substrate B is connected to the storage capacitor electrode 7 by using the conductive spacer 11, and the liquid crystal 10 is injected between the counter substrate B and the drive substrate A. Then, the liquid crystal display device is completed.

Since the thin film transistors 3 _{-1 to} 3 _-n can be formed directly on the glass substrate 1 as described above,
Thin film transistors 3 _{-1 to} 3 _-n and gate bus lines 4,
The drain bus line 5 can be stably formed. Therefore,
Thin film transistors 3 _{-1 to} 3 _-n and gate bus lines 4,
A defect such as a short circuit of the drain bus line 5 can be prevented, and a highly reliable liquid crystal display device can be realized.

Further, the storage capacitor electrode 7 is formed on the thin film transistors 3 _{-1 to} 3 _{-n, the} gate bus line 4 and the drain bus line 5 by using a light-shielding conductive material,
The storage capacitor electrode 7 is formed also as a light shielding film. Therefore, it is possible to suppress the generation of a leak current due to light, stabilize the operation characteristics, and obtain a clear image.

Furthermore, since the storage capacitor electrode 7 is connected to the counter electrode 8 by using the conductive spacer 11 and the storage capacitor electrode 7 and the counter electrode 8 are set to the same potential to form the storage capacitor, the capacitor is formed outside. There is no need to provide unnecessary connection lines.

[0043]

As described above, according to the present invention, the thin film transistor, the drain bus line, and the gate bus line pixel electrode are formed on the substrate by forming the storage capacitor electrode on the thin film transistor, the drain bus line, and the gate bus line. Since it can be directly formed on the thin film transistor, the thin film transistor, the drain bus line, and the gate bus line can be formed stably and without defects, and thus, a highly reliable liquid crystal display device can be realized. ..

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of an embodiment of the present invention.

FIG. 2 is a cross-sectional view of another main part of the embodiment of the present invention.

FIG. 3 is a plan view of an essential part of an embodiment of the present invention.

FIG. 4 is a diagram for explaining a manufacturing process according to an embodiment of the present invention.

FIG. 5 is a configuration diagram of an example of a liquid crystal display device.

FIG. 6 is a sectional view of a conventional example.

[Explanation of symbols]

A TFT panel B Counter substrate 1 Glass substrate 2 _-1 to 2 _-n Pixel electrode 3 _{-1 to} 3 _-n Thin film transistor (TFT) 7 Storage capacitor electrode

Front page continued (72) Inventor Takehiro Nakamura 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Within Fujitsu Limited

Claims (4)

[Claims] 1. A predetermined number of pixel electrodes (2 _-1 to 2 _-n ) on a transparent substrate (1) and a thin film transistor (3 _-1 to) adjacent to the pixel electrodes (2 _-1 to 2 _-n ). 3 _-n ) is formed between the drive substrate (A) and the counter substrate (B) having the counter electrode (8) facing the drive substrate (A).
0) is interposed and a voltage is applied between the pixel electrodes (2 _-1 to 2- _n ) and the counter electrode (8) to change the state of the liquid crystal to perform display. , The pixel electrodes ( _2-1 to 2) on the uppermost layer through an insulating film (6).
_-n ) A liquid crystal display device having storage capacitor electrodes (7) formed around each of them. 2. The liquid crystal display device according to claim 1, wherein the storage capacitor electrode (7) is formed of a light-shielding conductive material. 3. The liquid crystal display device according to claim 1, wherein the storage capacitor electrode (7) is connected to the counter electrode (8) and has the same potential as the counter electrode (8). .. 4. The liquid crystal according to claim 3, wherein the storage capacitor electrode (7) is connected to the counter electrode (8) through a liquid crystal (10) by a conductive spacer (11). Display device.