JP3239504B2 - Method of manufacturing thin film transistor matrix - Google Patents

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 (TFT) matrix formed on a liquid crystal panel or the like by an active matrix driving method.

In recent years, TFT matrix type liquid crystal panels used for laptop personal computers and wall-mounted televisions have been developed. Although the display quality of TFT matrix type liquid crystal panels has been recognized to be equivalent to that of CRTs, there is still room for improvement in price, reliability, and manufacturing yield.

[0003]

2. Description of the Related Art In an active matrix driving type liquid crystal panel, TFTs are arranged in a matrix corresponding to individual pixels for dot display, and each pixel is provided with a memory function to enable multi-line display with high contrast. .

FIG. 4 is a plan view of a TFT matrix. TF
The T matrix type liquid crystal panel applies a driving voltage to a large number of gate bus lines 41 and a plurality of drain bus lines 42 arranged in a matrix so as to intersect in the X and Y directions, and the TFTs connected to the intersections of both bus lines. By selectively driving 43, a corresponding desired pixel is displayed in dots. The structure of such a TFT matrix is, for example, that a large number of gate bus lines and drain bus lines made of titanium (Ti) -aluminum (Al) are formed on a transparent insulating glass substrate by an interlayer made of silicon nitride (SiN). They are arranged so as to intersect in the X and Y directions via an insulating film, and a TFT is connected to the intersection of both bus lines. When an amorphous silicon (a-Si) layer is used as the operating semiconductor layer of the TFT, a silicon nitride film (SiN) or a silicon nitride oxynitride (SiN) film formed by a plasma vapor deposition (P-CVD) method is used as a gate insulating film. (SiNO) film was used.

In the figure, 8D is the drain electrode of the TFT, 8S
Indicates the source electrode of the TFT, and 8C indicates the storage capacitor upper electrode (auxiliary capacitor bus line). 5A to 5F are cross-sectional views illustrating the steps of manufacturing a conventional TFT element.

In FIG. 5A, an Al film and a Cr film are continuously formed by sputtering on a glass substrate 1 as a transparent insulating substrate, and the resist film is patterned by photolithography. To form a gate electrode 2 and a storage capacitor lower electrode 3.

Next, the resist film is peeled off, and the gate insulating film as the first insulating film and the SiN film as the storage capacitor dielectric film, and the a-Si film as the working semiconductor layer by the P-CVD method.
5. Continuously grow a SiN film 6 as a channel protective film. Here, instead of the CVD SiN film 4, an alumina film formed by an atomic layer epitaxy (ALD) method may be used as the first insulating film.

In FIG. 5B, patterning is performed so that the channel protective film 6 immediately above the gate electrode 2 is left. FIG.
In (C), an n ⁺ -type a-Si
The layer 7 and the metal film 8 for source / drain electrodes are continuously formed.

In FIG. 5D, the contact layer 7 and the metal film 8 for source / drain electrodes are patterned to form a drain electrode 8D, a source electrode 8S, and a storage capacitor upper electrode 8C.

In FIG. 5E, a SiN film is formed as a second insulating film 14 by a P-CVD method, and a contact hole is formed on the source electrode 8S and the storage capacitor upper electrode 8C. FIG.
In (F), an ITO film is formed as a transparent electrode film on the substrate, and the storage capacitor upper electrode 8C and the source electrode 8S are contacted and patterned to form the pixel electrode 11, thereby forming a TFT matrix.

[0011]

The second-layer insulating film 9 is formed to a thickness of 3000 to 4000.degree., But the quality of the film greatly changes depending on the film forming conditions. Due to this change in film quality, when a contact hole is formed in this film by dry or wet etching, the contact hole has a forward tapered, vertical, or reverse tapered cross-sectional shape as shown in FIG. In the case of a forward taper, there is no particular problem. When the ITO film 11 is formed, a contact can be made with the storage capacitor upper electrode and the source electrode through the contact hole. In the case of a reverse taper, a contact can be made. Display defects.

The second insulating film 9 is made of monosilane (SiH
₄ ) Since the film is formed in a strong reducing atmosphere mainly composed of ammonia and NH ₃ , even if a small amount of metal compound contamination remains on the base, it is reduced to generate conductive foreign substances. . For this reason, the substrate surface sometimes became conductive.

An object of the present invention is to improve the reliability and manufacturing yield of a TFT device by forming a contact hole formed in a second insulating film in a forward tapered shape and preventing conduction on the substrate surface, thereby improving the reliability of the device and the manufacturing yield. .

[0014]

To solve the above problems, 1) a gate electrode 2 and a storage capacitor lower electrode 3 are formed on a transparent insulating substrate 1 and a first insulating film 4 is formed thereon. A step of sequentially forming a semiconductor layer 5 and a channel protective film 6; and a step of patterning the channel protective film so as to leave the channel protective film immediately above the gate electrode. A step of sequentially forming a contact layer 7 made of a semiconductor and a metal film 8 for a source / drain electrode;
Next, a step of patterning the contact layer and the source / drain electrode metal film 8 to form a drain electrode 8D, a source electrode 8S, and a storage capacitor upper electrode 8C, and then a transparent resin is formed on the substrate. A step of depositing a second-layer insulating film 9, a step of forming a contact hole in the second-layer insulating film on the source electrode and the upper electrode of the storage capacitor, and a step of forming a contact hole on the substrate. Forming a transparent electrode film, contacting the storage capacitor upper electrode and the source electrode with the transparent electrode film, and patterning the transparent electrode film to form a pixel electrode 11. 2) The method of manufacturing a thin film transistor matrix according to 1) above, wherein the second insulating film 9 is a thermosetting resin, a photosetting resin, or a photosensitive resin. It is achieved by the method of manufacturing the thin film transistor matrix to form a transparent insulating transparent insulating film covering the pixel electrode 11 formed on the substrate 1.

[0015]

In the present invention, a transparent resin film is used as the second insulating film instead of CVD SiN. This is the result of the present inventors confirming that the resin film does not have a variation in the cross-sectional shape of the contact hole due to the film formation conditions observed in the P-CVD method, and that it can be stably formed without forming a reverse taper. It is a thing using.

Further, since the resin is used, the residue of the metal compound is not reduced, and the resin surface is flattened by spin coating.

[0017]

【Example】

Embodiment (1): FIGS. 1A to 1F are cross-sectional views of an embodiment (1) of the present invention.

In FIG. 1A, a 1000 .mu.m thick Al is sputtered on a glass substrate 1 as a transparent insulating substrate.
A film and a Cr film having a thickness of 1000 mm are successively formed, the resist film is patterned by photolithography, and then etched using the resist film as a mask to form a gate electrode 2 and a storage capacitor lower electrode 3.

Next, the resist film is peeled off, and a 4000-nm-thick silicon nitride (SiN) film is formed by a P-CVD method as a gate insulating film as a first insulating film and a storage capacitor dielectric film.
4, a 150-mm thick a-Si film as a working semiconductor layer, and a 1200-nm thick SiN film 6 as a channel protective film are continuously grown.
Here, instead of the SiN film 4, an alumina film formed by an ALD method may be used as the first insulating film.

In FIG. 1B, patterning is performed so that the channel protective film 6 immediately above the gate electrode 2 is left. FIG.
In (C), the contact layer is 600 mm thick on the substrate.
The n ⁺ -type a-Si layer 7 and a metal film 8 for a source / drain electrode made of a chromium (Cr) film having a thickness of 1500 ° are continuously formed.

In FIG. 1D, a contact layer 7 and a metal film 8 for source / drain electrodes are patterned to form a drain electrode 8D, a source electrode 8S, and a storage capacitor upper electrode 8C.

In FIG. 1E, a transparent thermosetting resin film is applied as a second insulating film 9 and cured (heat treated).
I do. The thermosetting resin is, for example, a silicon-based or epoxy-based thermosetting resin, and is applied by spin coating or printing, and after curing, has a predetermined thickness of 0.4 μm. In the case of the printing method, the resin may not be attached to the connection terminals on the substrate.

Next, a resist film 10 having an opening on the source electrode and the storage capacitor is formed on the substrate by photolithography. In FIG. 1F, using the resist film 10 as a mask, the thermosetting resin film is etched to form a contact hole, and the resist film 10 is removed. At this time, the resin on the connection terminals is also removed by etching.

Next, a pixel electrode film having a thickness of 700
(1) ITO film is formed, and the storage capacitor upper electrode (8C) and the source electrode (8S) are contacted and patterned to form a pixel electrode.
11, and form a TFT matrix.

Embodiment (2): In Embodiment (1), a transparent thermosetting resin film was used as the second insulating film 9, but instead of this, a photocurable resin such as a UV resin was used. Use, Example
A film may be formed in the same manner as in (1).

Embodiment (3): FIG. 2 is a sectional view of an embodiment (3) of the present invention. A photosensitive resin, for example, a photosensitive polyimide resin is used as the second insulating film 9, and a photosensitive mask is used to pattern the photosensitive polyimide resin to form contact holes on the source electrode 8S and the storage capacitor upper electrode 8C. .

Embodiment (4): FIG. 3 is a sectional view of an embodiment (4) of the present invention. In this example, a TFT is formed by using the transparent resin film 9 of the present invention or the conventional SiN film 14 as the second insulating film.
After the formation, a transparent insulating film is formed as a protective film 13 on the substrate surface. At this time, no protective film is formed on the connection terminal. Alternatively, the film may be formed and then removed by etching. The substrate surface is flattened by the protective film 13, so that the next step can be performed with high accuracy.

Next, the effects of the embodiment will be summarized. (1) Since a resin film is used for the second insulating film, film formation is easy, and a film forming apparatus can be simplified and downsized. When a photosensitive resin is used, the step of applying a resist can be omitted. (2) Since the film formation conditions of resin are stable, it is possible to eliminate the conventional reverse taper shape when forming contact holes. Therefore, since the shape of the contact hole is stabilized, disconnection can be prevented when the ITO film of the pixel electrode film is formed. (3) Since it is a resin, reduction of metal oxide residues is eliminated, and conduction on the substrate surface can be prevented. (4) Since the resin film depends on spin coating, the substrate surface can be flattened. (5) Reliability and manufacturing yield can be improved, and lower prices can be realized.

[0029]

According to the present invention, in the manufacture of a TFT device, a contact hole formed in the second insulating film can be formed in a forward tapered shape, and conduction of the substrate surface can be prevented. As a result, the present invention was able to contribute to the improvement of the device reliability and the manufacturing yield.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment (1) of the present invention.

FIG. 2 is a sectional view of an embodiment (3) of the present invention.

FIG. 3 is a sectional view of an embodiment (4) of the present invention.

FIG. 4 is a plan view of a TFT matrix.

FIG. 5 is a cross-sectional view illustrating a manufacturing process of a conventional TFT element.

FIG. 6 is a sectional view of a contact hole.

[Explanation of symbols]

1 Glass substrate with transparent insulating substrate 2 Gate electrode 3 Lower electrode of storage capacitor 4 First layer insulating film (gate insulating film and dielectric film of storage capacitor) SiN film 5 Working semiconductor layer a-Si film 6 Channel protective film a transparent resin film 10 resist film 11 pixel electrode in the SiN film 7 contact layer is n ⁺ -type a-Si layer 8 source drain electrode metal film 8D drain electrode 8S source electrode 8C storage capacitor upper electrode 9 second layer insulating film ITO film

Claims (3)

(57) [Claims] A step of forming a gate electrode and a storage capacitor lower electrode on a transparent insulating substrate, and sequentially forming a first insulating film, a working semiconductor layer, and a channel protective film thereon; Patterning the channel protective film so as to leave the channel protective film immediately above the gate electrode, and then forming a contact layer made of a high concentration semiconductor and a metal film for source / drain electrodes on the substrate in this order Forming a drain electrode, a source electrode, and a storage capacitor upper electrode by patterning the contact layer and the source / drain electrode metal film; and forming a second layer of a transparent resin on the substrate. Forming a contact hole in the second insulating film on the source electrode and the upper electrode of the storage capacitor, and then forming a contact hole on the substrate. Forming an electrode film, contacting the storage capacitor upper electrode and the source electrode with the transparent electrode film, and patterning the transparent electrode film to form a pixel electrode. A method for manufacturing a thin film transistor matrix. 2. The method according to claim 1, wherein the second insulating film is a thermosetting resin, a photocurable resin, or a photosensitive resin. 3. The method according to claim 1, further comprising the step of forming a transparent insulating film covering the pixel electrode formed on the transparent insulating substrate.