JPH04273166A - Thin film transistor array substrate - Google Patents

Abstract

PURPOSE:To prevent electrostatic breakdown of a thin film transistor by preventing generation of voltage difference of charges induced on a thin film transistor due to electrostatic electricity charged at the rear surface side of a thin film transistor array substrate. CONSTITUTION:A conductive film (transparent conductive film) 2 is formed at the rear surface of an array substrate comprising a thin film transistor consisting of a gate 3, a drain 6 and a source 7 for on-off control of a display electrode 8 of a liquid crystal display apparatus provided at the front surface of a glass substrate 1, static electricity charged at the rear surface of the glass substrate 1 is unified and thereby generation of potential difference in the thin film transistor may be prevented.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to thin film transistor arrays used in active matrix liquid crystal displays.
Hereinafter, TFT (Thin Film Transistor)
or)] related to the substrate.

0002

2. Description of the Related Art Generally, TFT substrates used in liquid crystal displays and the like are manufactured by forming a thin film of various materials on a transparent insulating glass substrate and then repeating the process several times to form a desired pattern. And the completed TF
The T substrate has a conductive thin film as a gate, an insulating thin film as a gate insulating film, an amorphous silicon thin film, a conductive thin film as a source and a drain, and a conductive thin film as a display electrode on the surface of a glass substrate. They are each formed in a laminated state.

0003

[Problem to be solved by the invention] By the way, this type of T
In the FT substrate, static electricity may be charged on the back surface of the TFT substrate during transportation of the TFT substrate during its manufacture. Then, due to this charged static electricity, charges are induced on the TFT element side using the glass substrate as a capacitor. This static electricity is not uniform over the entire surface of the glass substrate, but has a distribution, and therefore the charge induced on the element side also has a distribution, causing a potential difference on the TFT element surface, and this potential difference causes the TFT element to There is a problem in that electrostatic discharge damage may occur. An object of the present invention is to provide a TFT substrate that prevents such electrostatic damage to TFT elements.

0004

[Means for Solving the Problems] The TFT substrate of the present invention includes:
A conductive film is formed on the back surface of an insulating substrate on which a plurality of TFT elements are arrayed. For example, in a TFT substrate used for a liquid crystal display or the like, a transparent glass substrate is used as an insulating substrate, and a transparent conductive film is formed on the back surface.

[0005]

According to the present invention, the electroconductive film on the back surface of the substrate uniformizes the distribution of static electricity, prevents potential difference in the TFT element, and prevents electrostatic damage.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings. FIG. 1 is a sectional view of a TFT substrate of the present invention. A gate 3 is formed of a conductive thin film on the surface of the glass substrate 1, and a gate insulating film 4 is formed thereon. Further, an amorphous silicon film 5 is formed on this gate insulating film 4 so as to cover the gate 3, and a drain 6 and a source 7 are formed thereon by conductive thin films. Further, on the gate insulating film 4, a display electrode 8 constituting a display electrode of a liquid crystal display device is formed of a conductive thin film, and is electrically connected to the source 7.

On the other hand, the back surface of the glass substrate 1 is coated with a transparent and conductive thin film, in this example, a 400 Å thick In2 film.
An O5 .SnO2 film (hereinafter referred to as an ITO film) 2 is formed. This ITO film 2 can be made of the same material as the display electrode 8. In this case, the ITO film 2 is formed prior to the formation process of the TFT element formed on the surface side of the glass substrate 1, and after the formation. Annealing treatment is performed at approximately 250°C. By performing this annealing, the thickness of the display electrode 8 is reduced to 40 in the subsequent process.
Even when a 0 Å thick ITO film is formed and etched, the ITO film 2 on the back side is annealed, so the etching rate of the ITO film 2 is about 1/10, and the display electrode 8 is Even during the etching during formation, the ITO film 2 is not etched away.

[0008] Therefore, in this TFT substrate, even if the back surface is charged with static electricity, the electrical conductivity of the ITO film 2 equalizes the charging, and a potential difference occurs due to the charges induced in the TFT elements on the front surface. Without a doubt, T
It becomes possible to prevent electrostatic damage to the FT element.

[0009]

Effects of the Invention As explained above, in the present invention, since a conductive film is formed on the back surface of an insulating substrate on which a TFT element is formed, the charged static electricity is uniformly distributed, so that there is no potential difference in the TFT element. This has the effect of preventing electrostatic damage to TFT elements.

[Brief explanation of the drawing]

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

[Explanation of symbols]

1 Glass substrate 2 ITO film (transparent conductive substrate) 3 Gate 5 Amorphous silicon film 6 Drain 7. Sauce 8 Display electrode

Claims (2)

[Claims] 1. A thin film transistor array electrode comprising a thin film transistor array substrate formed by arraying a plurality of thin film transistors on the surface of an insulating substrate, wherein a conductive film is formed on the back surface of the insulating substrate. [Claim 2] The insulating substrate is a transparent glass substrate,
2. The thin film transistor array substrate according to claim 1, wherein the conductive film formed on the back surface is a transparent conductive film.