JPH0627491A - Production of thin-film transistor - Google Patents

Abstract

PURPOSE:To prevent the generation of the etching residues of a transparent conductive film on a silicon nitride film subjected to a plasma damage at the time of forming islands and drains in the production of the thin-film transistors (TFTs). CONSTITUTION:Display picture elements consisting of the transparent conductive film 202 are formed on a transparent insulating substrate 201 and gates 203 are formed. The silicon nitride film 204, an amorphous silicon film 205 and an amorphous silicon film 206 doped with an impurity are subjected to film patterning, by which the islands and contact holes are formed. Further, sources 207 and drains 208 consisting of conductive films are formed and thereafter, channels 209 are formed and protective films 210 are formed. As a result, the patterning of the transparent conductive film on the silicon nitride film subjected to the plasma damage is prevented and the generation of the etching residues of the transparent conductive film is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a thin film transistor, and more particularly to a method of forming a display pixel made of a transparent conductive film.

[0002]

2. Description of the Related Art In a conventional thin film transistor, a gate 302 and a gate insulating layer 303 are first formed on a transparent insulating substrate 301 as shown in FIG. And plasma CVD
The silicon nitride film 304, the amorphous silicon film 305, and the impurity-doped amorphous silicon film 3
06 is continuously formed, and the amorphous silicon films 305 and 306 are patterned by dry etching to form islands. Again, the silicon nitride film 304 is patterned by dry etching to form a contact hole. After that, a conductive film is formed into a film pattern and the source 307 is formed.
And a drain 308 are formed, and a transparent conductive film 309 is further formed.
Is patterned into a film to form a display pixel. After forming the channel 310, the passivation film 3 is formed on the uppermost layer.
11 is formed and completed.

[0003]

In this conventional thin film transistor, since dry etching is used when forming the island, the source and the drain, plasma damage is given to the surface of the silicon nitride film. The surface of the silicon nitride film that has been damaged by this plasma has been a cause of producing etching residues of the transparent conductive film when the transparent conductive film is patterned.

[0004]

According to a method of manufacturing a thin film transistor of the present invention, a display pixel made of a transparent conductive film is formed before processing a gate insulating film or a transparent insulating substrate by a method such as photolithography. It has the feature of performing.

[0005]

The present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a thin film transistor according to a first embodiment of the present invention. First, the gate 1 is formed on the transparent insulating substrate 101.
02 is formed, and then the first gate insulating layer 103 is formed over the entire surface. Then, after forming the transparent conductive film 104 into a display pixel by forming a film pattern, a silicon nitride film 105 as a second gate insulating film, an amorphous silicon film 106, and an impurity-doped amorphous silicon film 107 are continuously formed by plasma CVD. Island and contact holes are continuously formed by continuous dry etching of the amorphous silicon films 106 and 107 and the silicon nitride film 105. Further, a source 108 and a drain 109 made of a conductive film are formed, then a channel 110 is formed, and finally a passivation film 111 is formed.

In the method of manufacturing a thin film transistor according to this embodiment, a transparent conductive film 104 is formed on a clean surface of the first gate insulating layer 103 which is not damaged by plasma before the island process formed by dry etching. Therefore, the etching residue of the transparent conductive film 104 is not generated on the first gate insulating layer 103. Further, the continuous dry etching of the island and the contact hole can reduce one photoresist process step as compared with the conventional example.

FIG. 2 is a sectional view of the thin film transistor of the second embodiment of the present invention. First, a transparent conductive film 202 is formed into a pattern on a transparent insulating substrate 201 to form display pixels, and then a gate 203 is formed. And plasma CVD
A silicon nitride film 204, which is a gate insulating film, an amorphous silicon film 205, and an impurity-doped amorphous silicon film 206 are continuously formed by the above method, and islands and contact holes are formed by continuous dry etching of the amorphous silicon films 205 and 206 and the silicon nitride film 204. Form continuously. Furthermore, the source 2 made of a conductive film
After forming 07 and drain 208, channel 209
And finally a passivation film 210 is formed.

In the method of manufacturing the thin film transistor of the second embodiment, the transparent conductive film 202 is formed on the surface of the clean transparent insulating substrate 201 which is not damaged by plasma before the island process formed by dry etching. Since the film is patterned, there is an effect that an etching residue of the transparent conductive film 202 is not generated on the transparent insulating substrate 201. Further, the continuous dry etching of the island and the contact hole can reduce one photoresist process step as compared with the conventional example.

FIG. 4 is a diagram comparing the occurrence rate of a short circuit between the drain display pixels due to the etching residue of the transparent conductive film between the conventional example and the present invention. As can be seen from this figure, in the present invention, about 40 to 70% occurs in the past, but it is zero in the present invention. In addition, one point indicates the rate of occurrence of short circuit in one TFT substrate.

[0010]

As described above, according to the present invention, the transparent conductive film is patterned on the clean gate insulating layer or the transparent insulating substrate that is not damaged by the plasma due to the dry etching. It has an effect that etching residues are not generated at all.

[Brief description of drawings]

FIG. 1 is a sectional view of a thin film transistor according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a thin film transistor according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view of a conventional thin film transistor.

[Fig. 4] Drain due to etching residue of transparent conductive film
It is a graph which shows the short circuit occurrence rate between display pixels.

[Explanation of symbols]

101, 201, 301 Transparent insulating substrate 102, 203, 302 Gate 103 First gate insulating layer 104, 202, 309 Transparent conductive film 105, 204, 304 Silicon nitride film 106, 205, 305 Amorphous silicon film 107, 206, 306 Impurity-doped amorphous silicon film 108, 207, 307 Source 109, 208, 308 Drain 110, 209, 310 Channel 111, 210, 311 Passivation film 303 Gate insulating layer

Claims (1)

[Claims] 1. On a transparent insulating substrate, a gate wiring, a gate insulating film, an island layer made of an amorphous silicon film and an amorphous silicon film doped with impurities, a display pixel made of a transparent conductive film, and a conductive film. In a thin film transistor having a source / drain wiring and a protective film, a display pixel formed of the transparent conductive film is formed by photolithography of the gate insulating film or the transparent insulating substrate as a base. A method for manufacturing a thin film transistor, which is performed before processing by the method described in 1.