JPH02275417A - Thin film transistor for display element - Google Patents

Abstract

PURPOSE:To prevent a display electrode from defective short-circuiting even if a pattern defect is generated and to improve the yield by forming an insulating film after a gate electrode is formed, then forming a display electrode and a gate insulating film, and coupling the display electrode with the source electrode of the thin film transistor(TFT) through through-hole wiring with drain wiring metal. CONSTITUTION:The insulating film 3 is formed on the gate electrode 2, the display electrode 4 is formed on it, and the gate insulating film 5 and a semiconductor layer 6 are further formed thereupon. The display electrode 4 and TFT 8 are connected electrically to each other through a through hole 9 formed in the gate insulating film 5. Namely, the display electrode 4 and gate 2 are separated by an SiO2 film 3 and the display electrode 4 and drain 7 are separated by a silicon nitride film which is the gate insulating film 5. Consequently, electrical short-circuiting never generated between the display electrode 4 and drain 7, and the short-circuiting defect can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thin film transistor used in an active matrix display.

[Conventional technology]

Conventionally, in this type of thin film transistor for a display element, the display electrode 4 is formed in the same plane as the drain 7, as shown in FIG. 5, which is a plan view of FIG. 4 and a BB cross-sectional view of FIG. It was said to have a similar structure.

[Problem to be solved by the invention]

In the conventional thin film transistor for a display element described above, since the drain and the display electrode are formed on the same surface, any pattern defect causes the display electrode to be electrically shorted to the train, resulting in an element defect. This element defect becomes a display defect in a display. Generally display electrode and fin. If the in-pattern space is widened, such short circuit defects will be reduced, but in order to increase the screen brightness in a display, it is desirable to make the display electrode as wide as possible, which increases the short circuit defects mentioned above. It ends up.

[Means to solve the problem]

The thin film transistor for a display element of the present invention has a structure in which an insulating film is formed on a gate electrode, a display electrode is formed on the insulating film, and a gate insulating film and a semiconductor layer are formed on the insulating film. Note that the display electrode and the thin film transistor are electrically connected through a through hole provided in the gate insulating film.

〔Example〕

Next, the present invention will be explained with reference to the drawings. FIG. 1 is a plan view of the first embodiment of the present invention, and FIG.
FIG. 2 is a sectional view taken along line A-A in FIG. 1;

The thin film transistor of this embodiment has a display electrode 4 and a gate 2.
are separated by a 5i02 film 3, and the display electrode 4 and drain 7 are separated by a silicon nitride film, which is a gate insulating film 5.

The thin film transistor of this example is formed by the following steps. 140% Cr is deposited on the glass substrate 1 by sputtering.
A gate 2 is formed by depositing a film of nm thickness and patterning it. After forming 1100 nm of SiO □ film 3 on it by sputtering or plasma CVD, 50 m of ITO (Indium Tin Oxide), which is a transparent conductor, is formed by sputtering, and the display electrode 4 is formed by patterning the ITO. Form. Thereafter, a 300 nm SiNx film was formed by plasma CVD as the gate insulating film 5 of the thin film transistor, and an 800 nm amorphous silicon layer (a-Sill) 6 was formed on top of it, and the a-Si layer other than the transistor part was removed by etching. ,
Through holes 9 are formed by etching the SiNx film on the display electrodes. Note that the a-Si layer 6 is an active layer of N-
It consists of a 300 nm thick a-3i layer and a 500 nm n''-a-3i layer which is an ohmic contact layer.The a-3i layer and SiNx film are usually etched using a dry etching method using a gas system containing CF4 or CF mixed with 02. After that, 2 Cr is added by sputtering.
A drain 7 and a source 8 are formed by forming a film with a thickness of 00 nm and patterning it. Source 8 is electrically coupled to display electrode 4 via through hole 9 . Finally, the n+-a-Si between the train 7 and the source 8 is removed by etching to complete the thin film transistor. Due to this structure, there is no electrical short circuit between the display electrode and the drain.

FIG. 3 is a longitudinal sectional view of a second embodiment of the invention. The gate 2 is formed of Ta with a thickness of 300 nm, and after the gate pattern is formed, the gate 2 is formed by anodizing.
A Ta205 film 10, which is an insulator, is formed on the surface.

Thereafter, a display electrode 4 is formed by forming a transparent conductive film and removing pattern defects, and a thin film transistor is formed by performing the same film forming and PR etching steps as in the first embodiment.

〔Effect of the invention〕

As explained above, the present invention forms an insulating film after forming a gate electrode, then forms a display electrode, then forms a gate insulating film, and connects the display electrode and the source electrode of the thin film transistor through the drain wiring metal. By connecting through the hole wiring, the display electrode is separated from the gate and train wiring by the insulating film, so even if a pattern defect occurs in each wiring layer or display electrode, it will not cause a short circuit failure in the display electrode, and the thin film transistor This has the effect of significantly improving the yield of arrays.

[Brief explanation of drawings]

FIG. 1 is a plan view of the first embodiment of the present invention, and FIG. 2 is a plan view of the first embodiment of the present invention.
1, FIG. 3 is a longitudinal sectional view of the second embodiment of the present invention, FIG. 4 is a plan view of a conventional thin film transistor, and FIG. 5 is B in FIG. -B sectional view. 1... Glass substrate, 2... Gate, 3... SiC
2 film, 4... display electrode, 5... gate insulating film, 6...
...Amorphous silicon layer, 7...Drain, 8.
...Source, 9...Through hole, 10...Ta2
05 membrane.

Claims (1)

[Claims] 1. In a thin film transistor for a display element having an inverted staggered structure, an insulating film is formed on the gate electrode, a display electrode is formed on it, and a gate insulating film and a semiconductor layer are formed on it. 1. A thin film transistor for a display element, characterized in that: 2. The thin film transistor for a display element according to claim 1, wherein the display electrode and the thin film transistor are electrically coupled via a through hole provided in the gate insulating film.