JPH0350527A - Substrate for thin-film transistor array - Google Patents

Abstract

PURPOSE:To suppress the increase of a transistor (TR) off current caused by irradiation of back light and to shut off the light leakage form the parts other than the display electrodes by executing the light shielding for thin-film TR regions outside the display electrode forming regions by the light shielding films provided on a transparent substrate. CONSTITUTION:A Cr film is deposited on the glass substrate 1. The Cr film of the parts corresponding to the display electrode forming regions is selectively etched and apertured to form the light shielding films 2. An interlayer insulating film 3 deposited with a silicon nitride film is formed on the surface including the light shielding film 2. The Cr film is deposited on the interlayer insulating film 3 and is selectively etched to form gate electrodes 4 on the interlayer insulating film 3 or the light shielding films 2 and a silicon nitride film is deposited on the surface including the gate electrodes 4 to form a gate insulating film 5. ITO films are selectively provided on the gate insulating film 5 on the apertures of the light shielding films 2 to form display electrodes 7. The increase of the TR off current caused by the irradiation of the back light is suppressed in this way and the light leakage from the parts other than the display electrodes 7 is shut off.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a thin film transistor array substrate.

[Conventional technology]

A thin film transistor array substrate used in an active matrix liquid crystal display is constructed by having an array of thin film transistors with an amorphous silicon film as an active layer on a transparent substrate such as glass. FIG. 2 is a cross-sectional view of a conventional thin film transistor array substrate. Glass substrate 1
A gate electrode 4 provided above, a gate insulating film 5 provided on the surface including the gate electrode 4, an amorphous silicon film 6 provided on the gate insulating film 5, and a drain provided connected to the amorphous silicon film 6. A thin film transistor is formed by the electrode 8 and the source electrode 9, and the display electrode 7 serving as a display area is connected to the source electrode 9 of the transistor, and display is performed by controlling the potential of the display electrode 7 with the transistor.

[Problem to be solved by the invention]

The conventional thin film transistor array substrate described above has a problem in that the off-state current of the thin film transistor increases due to light irradiation because light is not blocked from the back side of the glass substrate.

The semiconductor layer of a thin film transistor is partially shielded from light by the gate electrode, but due to multiple reflections between the gate electrode and the drain/source electrodes, the semiconductor layer is exposed to light and off-current due to photocarriers is generated. be. In addition, there is a problem that light leaks from outside the display electrode.
This is normally blocked by a metal pattern provided on the opposing substrate, and measures are taken to prevent it from becoming transmitted light, that is, display light, but in this case, it is necessary to bond two glass substrates together with high precision, and This will be difficult in terms of accuracy and size.

[Means to solve the problem]

The thin film transistor array substrate of the present invention includes a light shielding film provided on a transparent substrate and having an opening in a display electrode forming area, a glabella insulating film provided on a surface including the light shielding film, and an interlayer between the layers on the light shielding film. The device includes a thin film transistor provided on an insulating film, and a display electrode provided on the interlayer insulating film connected to the thin film transistor and aligned with the opening. [Example] Next, the present invention will be explained with reference to the drawings. FIGS. 1(a) and 1(b) are a plan view and a sectional view taken along the line AA' of an embodiment of the present invention.

Figure 1(a). As shown in (b), a C film is deposited to a thickness of 100 nm on the glass substrate 1 by sputtering, and holes are formed by selectively etching the Crli in the portion corresponding to the display electrode forming area. Form a light shielding film 2. next,
A silicon nitride film is deposited to a thickness of 400 nm on the surface including the light shielding film 2 by the CVD method to form a glabellar insulating film 3.
Next, a C film is deposited to a thickness of 120 nm on the glabellar insulating film WA3, and this is selectively etched to form a gate electrode 4 on the glabellar insulating film 3 on the light shielding film 2. .

Next, a silicon nitride film is applied to the surface including the gate electrode 4 for 40 minutes.
A gate insulating film 5 is formed by depositing it to a thickness of 0 nm. Next, the amorphous silicon film 6 and the n'' type diffusion layer 6a provided on the surface of the amorphous silicon are selectively formed on the gate insulating film 5 corresponding to the gate electrode 4, and the light shielding film 2 is formed.
A 40 nm thick IT
Display electrodes 7 are formed by selectively providing an O film. here,
The display electrode 7 is formed so as to overlap the periphery of the opening of the light-shielding film 2 with a width of 4 μm. Next, AI! is applied to the surface including the amorphous silicon film 6. A film is deposited to a thickness of 400 nm and selectively etched to form the drain electrode 8 and the source electrode f! Form 9. Ru. Next, using the source/drain electrodes 9 and 8 as a mask, n of the region corresponding to the gate electrode 4 is
The + type diffusion layer 6a is removed to form a thin film transistor array substrate. Here, the light-shielding film 2 is kept at an appropriate potential, but in an active matrix liquid crystal display, the light-shielding film 2 is kept at a potential of a counter electrode.
It is advantageous to form a storage capacitor between the display electrode 7 and the display electrode 7. [Effects of the Invention] As explained above, the present invention can increase transistor off-current due to backlight irradiation by shielding thin film transistor regions other than the display electrode shape region from light using a light shielding film provided on a transparent substrate. This has the effect of suppressing light leakage from outside the display electrodes. In addition, since this light-shielding film is formed by patterning using photolithography technology on the same substrate as the thin-film transistor, it is possible to control the relative position with the transistor display electrode with high precision, making it possible to achieve high precision and increase size. It's advantageous.

[Brief explanation of drawings]

Figure 1(a). (b) is a plan view and a sectional view taken along the line AA' of an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional thin film transistor array substrate. DESCRIPTION OF SYMBOLS 1... Glass substrate, 2... Light shielding film, 3... Interlayer insulating film, 4... Gate electrode, 5... Gate insulating film, 6
...Amorphous silicon film, 6a...n+ type diffusion layer, 7...display electrode, 8...drain electrode, 9...
・Source electrode.

Claims (1)

[Claims] A light-shielding film provided on a transparent substrate and having an opening in a display electrode formation region, an interlayer insulating film provided on a surface including the light-shielding film, and a thin film transistor provided on the interlayer insulating film on the light-shielding film. A thin film transistor array substrate comprising: a display electrode connected to the thin film transistor and provided on the interlayer insulating film in alignment with the opening.