JPS62291062A - Manufacture of thin film transistor - Google Patents

Abstract

PURPOSE:To facilitate manufacturing a TFT with high reliability in which the discontinuity of a drain electrode or a source electrode is eliminated with a high yield by a method wherein the drain electrode is formed after the island part of the TFT which is in contact with the drain electrode or the source electrode is worked to have right-angled shapes or zig-zag shapes. CONSTITUTION:A metal layer is applied to a light transmitting insulating substrate to form a gate electrode 2, and an insulating film 3 and an active layer 4 are successively formed on the gate electrode 2. Then the parts of the gate insulating film 3 and the active layer 4 which are in contact with a drain electrode 5 or a source electrode 6 are worked to have right-angled shapes 10 and 11 or zig-zag shapes 12 and 13 to form the island of a transistor, and then the drain electrode 5 and the source electrode 6 are formed on the island. With this constitution, the length of the step of a part formed by putting the drain electrode 5 or the source electrode 6 on the island is increased and etchant hardly penetrates into the stepped part so that the problem of discontinuity of the drain electrode or the source electrode during the processing can be solved.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention (Field of Industrial Application) This invention provides a highly reliable thin film transistor (hereinafter referred to as TP).
(abbreviated as T).

(Prior Art) FIG. 3 is a plan view of the main parts of a conventional TPT, and FIG. 4 is a sectional view of this TPT. A in both figures.

A', c, and c' correspond to each other. Referring to FIGS. 3 and 4, a conventional TPT manufacturing method will be described.

As shown in FIGS. 3 and 4, a transparent insulating substrate 1
On top, nichrome (NjCr) and tungsten (W).

A metal layer made of molybdenum (Mo), chromium (Cr), etc. is deposited to a thickness of 200 to 1000 mm by vacuum evaporation or sputtering, and processed into a predetermined pattern to form the gate electrode 2.

On top of that, a silicon nitride film (Si
Nx) is deposited to a film thickness of 0.3 μm to 0.5 μm by a glow discharge method using NH3 and 5IH4 as main component gases.

Furthermore, on top of that, an amorphous silicon film with an active level of 0.1 to 0.0
．． After depositing 2 μm, the portion other than the portion that will become TPT is processed, removed, and nose-turned into an island shape to form a gate insulating film 3 and an active layer 4.

Next, the drain electrode 5. 0, 5 to 1, which becomes the source electrode 6
．． The TPT is completed by forming an aluminum (b) layer iAZ with a thickness of 0 μm by vacuum evaporation and processing.

This TPT is then used as a TFT array of a liquid crystal display device by forming a transparent electrode 7 so as to be connected to the source electrode 6, and arranging the TPT and the transparent electrode two-dimensionally.

(Problems to be Solved by the Invention) However, in such a conventional TPT manufacturing method, the thin film of the gate insulating film 3 and the active M4
Due to the 0.7 μm step B (Figure 4), the slap coverage of the M layer is poor, and the drain electrode 5 is prone to disconnection as shown by C and C' in Figures 3 and 4 during processing. There was a point.

In order to prevent this, it is conceivable to increase the width of the drain electrode 5, but this increases the size of the TPT element itself. Therefore, it is difficult to create a TPT panel by arranging TPT at high density.

This invention solves the problems of the above-mentioned prior art.
The present invention provides a complete method of manufacturing a thin film transistor that solves the problems of the drain electrode being easily disconnected and the difficulty of arranging TPTs in a high density.

(Means for Solving the Problems) The present invention introduces a step of forming a drain electrode after processing the shape of the TFTO island portion in contact with the drain electrode or the source electrode into a hook shape or a zigzag shape in a method for manufacturing a thin film transistor. This is what I did.

(Function) According to the present invention, the above-described steps are introduced in the method for manufacturing a thin film transistor, so that after forming the island of the TFT in contact with the drain electrode in a key shape or a zigzag shape, the drain electrode or the source electrode is formed. It is layered on top of the island, increases the length of the step at the overlapped part, and acts to make it difficult for etching liquid to enter the step.
Therefore, the above problem can be eliminated.

(Example) Hereinafter, an example of the method for manufacturing a thin film transistor of the present invention will be described with reference to the drawings. Fig. 1 is a plan view of the main part of a TPT for explaining one example.

In FIG. 1, the same parts as in FIGS. 3 and 4 will be described with the same reference numerals. In FIG. 1, a gate electrode 2 is formed on a transparent insulating substrate using a conventional technique, and a gate insulating film 3 and an active layer 4 are sequentially deposited on the gate electrode 2. As shown in FIG.

Next, the gate insulating film 3 and active layer 4 are processed to form TFTO islands (
element isolation). At this time, as shown in Figure 1,
A TFTO island (a-Si/S
iNx ) portion is shaped into a key shape (FIG. 1 10 and 11).

This method of processing the hook shapes 10 and 11 can be easily performed by plasma etching using a gas such as CFJ 102 using a resist as a mask.

After processing the key shape 10.11 in this way, the drain electrode 5.1 is processed again using the conventional technique. A pTFT is completed by depositing and processing the source electrode 6.

The reason why the shape of the island part of the TFT is partially made into a key shape and the drain electrode is overlaid on the key shape is as follows: (1) The length of the step at the overlapping part is longer than that of the conventional (straight line). υ
(2) By making the corner into a key shape, it becomes difficult for the etching solution to enter the step part.

Thereafter, transparent electrodes 7'f: are formed on this TPT in the same manner as in the prior art, and when the TPT and transparent electrodes 7 are arranged in two dimensions, it is used as a TFT array of a liquid crystal display device.

Moreover, the same effect can be obtained by using a zigzag shape 12, 13 as shown in FIG. 2 instead of the above-mentioned key shape.

(Effects of the Invention) As described in detail above, according to the present invention, after processing the shape of the island portion of the TFT that is in contact with the drain electrode or the source' polarity into a key shape or a zigzag shape, Since the electrode is formed by overlapping that part, it is possible to solve the problem of disconnection during processing, and therefore, it is possible to manufacture highly reliable TPT with high yield without disconnection of the drain electrode and source electrode. It becomes possible.

[Brief explanation of drawings]

FIG. 1 is a plan view of essential parts for explaining one embodiment of the method for manufacturing a thin film transistor of the present invention, and FIG. 2 is a plan view of essential parts for explaining another embodiment of the method of the present invention. 3
The figure is a plan view of the main parts for explaining the entire method of manufacturing a conventional 6i film transistor, and FIG. 4 is a sectional view of the main parts for explaining the conventional method. 2... Gate polarity, 3... Gate insulating film, 4...
Active layer, 5...Drain electrode, 6...Nose' pentode, 7...Transparent electrode, 10.11...Key shape, 12.
13... Zigzag type. Figure 1'

Claims (1)

[Claims] (a) A step of depositing a metal layer on a transparent insulating substrate to form a gate electrode; (b) A step of sequentially depositing an insulating film and an active layer on the gate electrode. (c) processing the portion of the gate insulating film and the active layer in contact with the drain electrode or the source electrode into a hook shape or zigzag shape to form a transistor island; (d) forming the drain electrode and the island in the island shape; A method for manufacturing a thin film transistor, comprising a step of depositing a source electrode.