JPH04367268A - Thin film transistor array device - Google Patents

Abstract

PURPOSE:To avoid the deterioration and the electrostatic breakdown of a TFT due to the external static electricity during the TFT manufacturing step by a method wherein a conductive transparent thin film is formed on the surface, rear surface and side of an insulating substrate. CONSTITUTION:A transparent conductive thin film 2 comprising an ITO film, an SnO2, etc., is formed on the surface, rear surface and side of a glass substrate 1. On the other hand, an insulating film 3 is provided on the surface and then a thin film transistor comprising a gate electrode 4, a silicon nitride film 5, an a-Si film 6, an n<+> type a-Si film 7, a drain electrode 8, a source electrode 9 is formed on the surface. Furthermore, a pixel electrode 10 is connected to the source electrode 9 of the thin film transistor while the surface of the thin film transistor and the pixel electrode 10 is covered with a silicon nitride film 11.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film transistor array device, and more particularly to a thin film transistor array device used in active matrix color liquid crystal display devices and the like.

0002

2. Description of the Related Art FIG. 2 is a sectional view of a conventional thin film transistor array device of this type. In the figure, 1 is a glass substrate, 2 is an ITO film formed on the entire back surface of the glass substrate 1, 4 is a gate electrode made of a Cr film, 5 is a silicon nitride film forming a gate insulating film, and 6 is an active layer. A non-doped amorphous silicon film (hereinafter referred to as a-Si film),
7 is an amorphous silicon film doped with phosphorus (P) at a high concentration (hereinafter referred to as an n+ type a-Si film) constituting a contact layer; 8 and 9 are a drain electrode and a source made of a Cr film, respectively; The electrodes 10 are pixel electrodes made of an ITO film, and 11 is a silicon nitride film deposited over the entire surface as a protective film.

[0003] Here, the ITO film 2 deposited on the back surface of the substrate
is provided to prevent the glass substrate from becoming locally charged due to contact with jigs and the human body during the manufacturing process, and to electrostatically shield internal devices after it is assembled into an LCD panel. It is a membrane.

0004

[Problems to be Solved by the Invention] In the conventional thin film transistor array device described above, although it is possible to prevent local charging on the back surface of the glass substrate, it is possible to prevent local charging from occurring on the back surface of the glass substrate. Localized charging cannot be avoided. Therefore, in the conventional example, localized overvoltage is likely to occur, and deterioration or destruction of the device cannot be completely prevented.

[0005]

[Means for Solving the Problems] The thin film transistor array device of the present invention has a plurality of thin film transistors connected to each thin film transistor through an insulating film on a glass substrate having a transparent conductive thin film formed on the front, back and side surfaces. The pixel electrode is provided with a pixel electrode.

[0006]

Embodiments Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing one embodiment of the present invention. To manufacture this example, first, an ITO film 2 is formed on a glass substrate 1 by a sputtering method. When using a normal sputtering device that can form only one side, sputtering is required twice: on the front side (element forming side) and on the back side. In this case, the jig is designed so that ITO is also sputtered onto the side surfaces. It is desirable that the film be formed on the entire side surface area, but if ITO is deposited on most areas and the ITO films on the front and back sides are securely connected, the purpose of the present invention will actually be defeated. Never.

[0007] The temperature during ITO film formation is 200°C to 500°C.
Set within the range of ℃ according to the conditions of the post-process. 200℃
The ITO film may be formed at a low temperature below, but in this case,
To prevent the ITO film from being removed during the etching process in the subsequent manufacturing process, the
) is required.

Thereafter, a silicon oxide film 3 is formed by sputtering, a Cr film is deposited on it, and this is patterned to form a gate electrode 4.
A silicon nitride film 5, which will become a gate insulating film, is deposited by method D.

Next, an a-Si film 6 and an n+ type a-Si film 7 are grown by plasma CVD and patterned to form a thin film transistor region. Next, C
A drain electrode 8 and a source electrode 9 are formed by depositing an r film and patterning it to form an n+ type a-
The Si film 7 is removed by etching.

Next, an ITO film is formed by sputtering and patterned to form the pixel electrode 10. Furthermore, a silicon nitride film 11 serving as a protective film is grown by plasma CVD.

In this example, since a glass substrate whose entire surface is covered with an ITO film is used, the glass substrate will not be locally charged even if it comes into contact with charged jigs, tools, human bodies, etc. during the manufacturing process. You will no longer be exposed. Also in this example,
Localized charging of the insulating coating may occur during the manufacturing process. However, due to the presence of the conductive thin film relatively nearby, the charging is equalized, so that adverse effects on the device can be avoided.

It should be noted that the present invention is not limited to the above-mentioned embodiments; for example, the ITO film can be replaced with a SnO2 film. In addition, if a conductive thin film is provided on the entire surface of the glass substrate, the capacitance of the gate electrode and the gate electrode bus line (not shown) will increase, so if the circuit operation is adversely affected, the gate electrode and Part or all of the ITO film under the bus line can be removed. The same applies to the drain electrode and the drain bus line (not shown).

[0013]

As explained above, the present invention uses a glass substrate whose entire surface is covered with a transparent conductive thin film, and a thin film transistor and a pixel electrode are formed on the glass substrate. Local charging will not occur in the thin film transistor, and if local charging occurs in the insulating film related to the thin film transistor, it will be discharged quickly, so deterioration and destruction of the device can be reliably avoided.

Furthermore, since a conductive thin film is formed entirely under the pixel electrode, there is also the secondary effect that a large storage capacity of the pixel electrode can be ensured.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention.

FIG. 2 is a sectional view of a conventional example.

[Explanation of symbols]

1...Glass substrate, 2...ITO film, 3...
silicon oxide film, 4... gate electrode, 5
... silicon nitride film, 6... non-doped amorphous silicon film (a-Si film), 7... P-doped amorphous silicon film (n+ type a-Si film),
8...Drain electrode, 9...Source electrode,
10... Pixel electrode, 11... Silicon nitride film.

Claims (2)

[Claims] 1. A glass substrate having a transparent conductive thin film formed on its front, back and side surfaces, an insulating film formed on the surface of the glass substrate, and a plurality of glass substrates arranged in a matrix on the insulating film. A thin film transistor array device including a thin film transistor and a plurality of pixel electrodes connected to each thin film transistor. 2. The thin film transistor array device according to claim 1, wherein at least a portion of the transparent conductive thin film under the gate electrode and the gate electrode bus line and under the drain electrode and the drain electrode bus line are removed.