JPH0638185B2 - Method of forming thin film transistor matrix - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] According to the present invention, a multilayer film is etched stepwise in order to improve yield, reduce cost and improve quality in a manufacturing process of a thin film transistor matrix for active matrix display of liquid crystal. At the same time, the number of photomasks used is reduced by adopting the step of coating the transparent conductive film on the stepwise etching end.

[Industrial application field]

The present invention relates to a method of forming a thin film transistor matrix for driving a liquid crystal, which controls blinking of a liquid crystal display.

Liquid crystal displays occupy a dominant position among flat displays due to the advantages of easy colorization, low power consumption, and low driving voltage, and are widely used. On the other hand, in order to increase the display capacity of the liquid crystal display and maintain high quality, it is necessary to form a large number of switch elements for controlling blinking of each pixel of the liquid crystal display.

In order to form this switch element, a thin film transistor matrix has been actively developed. This thin film transistor matrix requires precision in the manufacturing process, and has a large number of processes, so that its practical application has been delayed. Therefore, there is a demand for a method of forming a thin film transistor matrix that can be manufactured with a small number of steps and a high yield.

[Conventional technology]

Conventionally, the thin film transistor matrix is shown in FIGS. 5 (a) to (e).
The mask shown in FIG. 6 is used for the masks manufactured in the order of steps shown in FIG. That is, FIG. 6 (a)
The gate 2 is formed on the glass substrate 1 of the transparent insulating substrate shown in FIG. 5 (a) by using the first photomask 31 shown in FIG. After that, a gate insulating film 3, an amorphous silicon film (hereinafter referred to as a-Si film) 4 which is a semiconductor active layer, and a silicon oxide film (hereinafter referred to as SiO ₂ film) 5 are formed by plasma vapor deposition (hereinafter referred to as plasma CVD method). (Note)), a positive resist is applied to the entire surface and exposed from the back surface of the glass substrate 1 to leave the positive resist 11 only on the gate 2. In this state, the SiO ₂ film 5 is etched to complete the step shown in FIG.

Next, n a-Si / Ti (titanium) / Al (aluminum) 6
Is formed and lift-off is performed together with the positive resist 11 to leave the portions to be the source electrode 6-2 and the drain electrode 6-1.
Get (b).

Using the second photomask 32 shown in FIG. 6 (c), n aS
i / Ti / Al6 is drain electrode 6-1 in a plane via gate 2
And at least a-Si so that the source electrode 6-2 is separated.
The film 4 is etched to obtain FIG. 5 (c).

Next, the interlayer insulation layer of the high resistance coating material, that is, polyimide 7
Is applied to the entire surface, and the third photomask 3 shown in FIG.
By using 3, the display portion including the drain pattern and a part of the source electrode is removed by etching. Next, using a fourth photomask 34 shown in FIG. 6 (d), a transparent electrode is formed on the display portion.
13-1 is formed to obtain FIG. 5 (d).

Furthermore, after depositing Cr (chrome) and Al on the entire surface, FIG.
Using the fifth photomask 35 shown in (e), the source electrode 6
The connection metal 17 for connecting -2 and the transparent electrode 13-1, the light shielding film 10 for shielding the gate and the drain bus 12 are patterned to obtain FIG. 5 (e).

As described above, five photomasks are required in the process of manufacturing the conventional thin film transistor matrix.

[Problems to be solved by the invention]

As described above, conventionally, since the photomasks are made to correspond to the respective constituent elements, there arises a problem that the number of photomasks increases, the number of steps increases, the manufacturing cost increases, and the yield deteriorates. .

It is an object of the present invention to provide a method for forming a thin film transistor matrix which can reduce the number of steps and further improve the yield from the above conventional circumstances.

[Means for solving problems]

The present invention, as shown in the first principle diagram of FIG.
The photoresist 11 is coated between the stacked layers of the source electrode, the contact material 6 to be the gate electrode layer, the interlayer insulating film 7 and the metal film 8 provided on the transparent insulating substrate 1 of FIG. As shown in (b), the contact material 6, the interlayer insulating film 7, and the contact material 6 are etched right under the photoresist 11, and then the interlayer insulating film 7 is over-etched as shown in FIG. 1 (c). Further, as shown in FIG. 1 (d), the metal 8 is over-etched to make the end faces of the metal film 8, the interlayer insulating layer 7 and the contact material 6 stepwise. The above steps are performed using the second photomask 22.

Further, as shown in the second principle diagram of FIG. 2, a transparent conductive film 9 is formed on the entire surface of the metal film 8 and the transparent insulating plate 1, and the transparent conductive film 9 is formed as shown in FIG.
(a) is prepared, and a photoresist 11 is formed using a third photomask to prepare FIG. 2 (b). When the transparent conductive film 9 and the metal film 8 are continuously etched and the photoresist is removed, FIG. 2C is obtained.

[Action]

As shown in the first principle, by overetching the interlayer insulating film 7, using the second photomask,
The contact material 6 and the metal film 8 can be taken out, and according to the second principle, the display electrode, the light-shielding film, and the connection metal can be manufactured by the third photomask, and the type of photomask to be used is reduced. To simplify the manufacturing of the thin film transistor matrix and improve the product quality.

[Embodiment] FIG. 3 is a process drawing showing an embodiment of the present invention, and FIG. 4 is a plan view of a mask used in the present invention. Third
As shown in Figure (a), a glass substrate 1 which is a transparent insulating substrate.
A gate 2 with a gate bus line is formed on the top of the gate using the first photomask 21 shown in FIG. After this fabrication, the gate insulating film 3, the amorphous silicon (a-Si) film 4 to be the semiconductor active film, and the channel portion protective film (Si
O ₂ ) 5 is formed into a film, and the contact material 6 to be the source electrode 6-2 and the drain electrode 6-1 is produced by the self-alignment method as in the conventional method, and FIG. 3 (a) is obtained.

Next, as shown in FIG. 3B, a polyimide 7 and a metal 8 which will be an interlayer insulating film and a protective film of the transistor matrix are formed.

After the above steps, a photoresist is coated and etching is performed using the second photomask 22 shown in FIG. 4 (c). This etching is performed by the method shown in the first principle diagram of FIG. 1 described above, and the contact material 6 is protruded from the end face (edge) of the polyimide 7 to obtain FIG. 3 (c).

After that, after covering the entire surface of the transparent conductive film 9 and applying a photoresist, a mask pattern is formed using the third photomask 23 shown in FIG. 4 (d), and the transparent conductive film 9 and the metal 8 are formed. Etching is sequentially performed as shown in the second principle of FIG. 2 to form the drain bus 12, the light-shielding film 9-2 and the display electrode 9-3, and FIG. 3 (d) is obtained.

〔effect〕

As is clear from the above description, according to the present invention, the source electrode and the drain electrode are separated and taken out by the same mask by the side etching of the interlayer insulating film (polyimide), and after the transparent conductive film is formed, the display electrode is formed. , Light shielding film,
By patterning the drain bus line with a single photomask, the number of photomasks used can be reduced, which is extremely effective in reducing the number of manufacturing steps and improving the quality.

[Brief description of drawings]

FIG. 1 is a first principle diagram of the present invention, FIG. 2 is a second principle diagram of the present invention, FIG. 3 is a process diagram showing an embodiment of the present invention, and FIG. 4 is used in the present invention. FIG. 5 is a plan view of a photomask, FIG. 5 is a process diagram showing a method of forming a conventional thin film transistor matrix, and FIG. 6 is a plan view of a mask used in the conventional process. In the figure, 1 is a glass substrate, 2 is a gate, 3 is a gate insulating film, 4 is amorphous silicon, 6 is a contact material, 7 is an interlayer insulating film, 8 is a metal film, 9 is a transparent conductive film, 2
Reference numerals 1, 22, 23 and 31 to 35 denote photomasks.

Claims (2)

[Claims] 1. A gate (2) with a bus line made of an opaque metal is formed on a transparent insulating substrate (1) using a first mask (21), and at least a gate insulating film (3) and a semiconductor active layer are formed thereon. Layers (4) were sequentially formed, a positive photoresist was applied on the layers, and the back surface of the transparent insulating substrate (1) was exposed to leave the resist only on the gates with bus lines (2). After that, a step of forming a contact material (6) to be the layer of the source electrode and the drain electrode on the entire surface and performing lift-off, and an interlayer insulating film (7) and a metal film (7) on the substrate after the lift-off.
8) is sequentially formed on the entire surface, and then the gate with bus line (
The pattern of the source electrode (6-2), the drain electrode (6-1), and the drain bus line (12) is etched using the second photomask (22) that crosses the pattern of 2) at the pattern end. Become stepwise, and the contact material (6)
At least 50 Å exposed so that the semiconductor active layer (
A step of etching up to 4), and a transparent conductive film (9) on the substrate on which the source electrode (6-2), the drain electrode (6-1) and the drain bus line (12) are formed.
Then, the drain bus pattern (14) that covers a part of the edge of the drain electrode (6-1), the light shield pattern (15) that covers the gate (2), and the source electrode (6-2 )
The transparent conductive film is formed by using a third photomask (23) including a display electrode pattern (16) that covers a part of the edge of the transparent conductive film.
A method for forming a thin film transistor matrix, which comprises a step of sequentially removing (9) and the metal film (8) by etching. 2. An insulating film (5) is subsequently formed after the semiconductor active layer (4) is formed, and the insulating film (5) is formed on the back surface of the substrate before the contact material (6) is formed. The method of forming a thin film transistor matrix according to claim 1, wherein a step of etching using a resist pattern formed by exposure is added.