JPH0570824B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an active matrix liquid crystal display device used in portable electronic devices such as pocket televisions.

[Conventional technology]

FIG. 2 shows the structure of one substrate used in a conventional active matrix liquid crystal display device, which consists of a thin film transistor and a liquid crystal drive electrode. On the insulating substrate 11 are a gate electrode 12 and a gate insulating film 1.
3. Amorphous silicon 14, source and drain 15, 16 made of N+ amorphous silicon, insulating film 1
7. A thin film transistor consisting of a source electrode 18 and a drain electrode 19, and a liquid crystal drive electrode 20 consisting of an ITO (indium tin oxide) transparent conductive film are formed. When a voltage is applied to the gate electrode 12 to turn on the thin film transistor, the video signal becomes
From the source electrode 18 to the channel part of the thin film transistor and through the drain electrode 19 to the liquid crystal drive electrode 2.
Can be added to 0.

[Problem that the invention seeks to solve]

However, in the conventional active matrix liquid crystal display device, the liquid crystal drive electrode 20 is transparent;
Since the source and drain electrodes 18 and 19 need to have low resistance, the liquid crystal drive electrode 20 includes ITO,
Since the source and drain electrodes 18 and 19 used a conductive film different from a metal film such as aluminum, the manufacturing process was complicated and the yield was poor.

Therefore, in order to solve these conventional drawbacks, the present invention aims to solve the problems of the conventional source and drain electrodes 18 and
9. It is an object of the present invention to obtain an active matrix liquid crystal display device in which electrode films necessary for liquid crystal drive electrodes 20 can be formed at the same time.

[Means for solving problems]

In order to solve the above problems, the present invention utilizes the fact that amorphous silicon and metal react to form a transparent conductive film to form a liquid crystal drive electrode 20 and source and drain electrodes 18 and 19. Similarly, it is formed from a conductive film.

[Effect]

It is known that when a two-layer film of amorphous silicon and a metal such as chromium or molybdenum is heated to 150 to 300°C and the metal film is removed by etching, a transparent conductive film is formed. (Yamamoto et al., Spring 1984 Proceedings of the Japan Society of Applied Physics, a-Si:Transparent electrodes based on interfacial reaction between H and metal, p381) As mentioned above, the liquid crystal drive electrode and the source and drain electrodes can be formed from the same conductive film. Accordingly, the number of electrode film forming steps can be reduced and the step of connecting the electrodes can be omitted.

〔Example〕

Embodiments of the present invention will be described below based on the drawings. FIG. 1 is a diagram showing the structure of one substrate consisting of a thin film transistor and a liquid crystal drive electrode used in the active matrix liquid crystal display device of the present invention. In FIG. 1, on an insulating substrate 1 are a gate electrode 2, a gate insulating film 3, amorphous silicon 4, a source and a drain made of a transparent conductive film formed by reacting N+ amorphous silicon with chromium. 5, 6, insulating film 7, source electrode made of chromium;
A thin film transistor consisting of drain electrodes 8 and 9 is formed. The liquid crystal drive electrode 10 includes a source,
A transparent conductive film formed by reacting N+ amorphous silicon forming the drains 5 and 6 with chromium;
They are made of the same membrane. source, drain 5,
6 and the liquid crystal drive electrode 10 are formed by depositing N+ amorphous silicon and chromium films continuously over the entire surface of the substrate, and then forming the source, drain 5, 6, source electrode, drain electrode 8, 9, and liquid crystal drive electrode. N+ amorphous silicon and chromium films are formed in a logical OR pattern of 10, and then heated to 150 to 300°C to react with chromium and N+ amorphous silicon to form transparent conductive films 5, 6, and 10. Then, the liquid crystal drive electrode 10 is formed.
Etch the chrome in the pattern.

In this way, if the liquid crystal drive electrode 10 and the transparent conductive film formed by the reaction of N+ amorphous silicon and chromium forming the sources and drains 5 and 6 are made of the same film, the electrode The number of film forming steps can be reduced and the step of connecting electrodes can be omitted.

The films forming the source and drain electrodes 8 and 9 may be not only a single layer of chromium, but also a double layer of aluminum and chromium, for example.

〔Effect of the invention〕

As explained above, this invention reduces the number of electrode film forming steps by using a transparent conductive film formed by reacting N+ amorphous silicon and chromium for both the liquid crystal drive electrode, the source, and the drain. This has the effect of realizing a low-cost active matrix liquid crystal display device that eliminates the step of connecting electrodes.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of one substrate of an active matrix liquid crystal display device according to the present invention, and FIG. 2 is a sectional view of one substrate of a conventional active matrix liquid crystal display device. 4...Amorphous silicon layer, 5...Source, 6...
...Drain, 10...Liquid crystal drive electrode.

Claims (1)

[Claims] 1. An active matrix liquid crystal display device in which a thin film transistor having an amorphous silicon semiconductor layer is provided as a switching element for each pixel, characterized in that at least an alloy film of metal and amorphous silicon is used as a liquid crystal drive electrode. Active matrix liquid crystal display device.