JPH06208137A - Manufacture of thin film transistor matrix - Google Patents

Abstract

(57) [Abstract] [Purpose] Regarding the manufacturing method of a thin film transistor (TFT) matrix, the contact hole formed in the second insulating film is made into a forward tapered shape and the conduction on the substrate surface is prevented, and the reliability and the manufacturing yield of the device are improved. For the purpose of improving. [Structure] 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,
The operating semiconductor layer 5 and the channel protection film 6 are sequentially formed, leaving the channel protection film directly above the gate electrode, and the contact layer 7 and the metal film 8 are sequentially formed on the substrate and patterned to form the drain electrode 8D and Source electrode 8S and storage capacitor upper electrode 8C
And the second insulating film made of transparent resin on the substrate.
Then, a contact hole is formed in the second insulating film, a transparent electrode film is formed on the substrate, the upper electrode of the storage capacitor and the source electrode are contacted, and the pixel electrode 11 is patterned. Configured to form.

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 in a liquid crystal panel or the like by an active matrix driving method.

In recent years, a TFT matrix type liquid crystal panel used for a laptop personal computer and a wall-mounted television has been under development. Although it is recognized that the TFT matrix liquid crystal panel has a display quality equivalent to that of a CRT, there is room for improvement in terms of price, reliability, and manufacturing yield.

[0003]

2. Description of the Related Art A liquid crystal panel based on an active matrix driving system has TFTs arranged in a matrix corresponding to individual pixels for dot display, and each pixel has a memory function to enable multi-line display with good contrast. .

FIG. 4 is a plan view of the TFT matrix. TF
The T-matrix liquid crystal panel applies a driving voltage to a large number of gate bus lines 41 and drain bus lines 42 arranged in a matrix so as to intersect in the X and Y directions, and is connected to the intersections of both bus lines. By selectively driving 43, the corresponding desired pixel is displayed in dots. Such a TFT matrix structure is constructed, for example, on a transparent insulating glass substrate with a number of gate bus lines made of titanium (Ti) -aluminum (Al) and drain bus lines made of silicon nitride (SiN) or the like. The TFTs are connected to the intersections of both bus lines by arranging them so as to intersect in the X and Y directions via an insulating film. Moreover, 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 (P-CVD) film is used as the gate insulating film. A SiNO) film was used.

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

In FIG. 5 (A), an Al film and a Cr film are successively formed on a glass substrate 1 as a transparent insulating substrate by sputtering, the resist film is patterned by photolithography, and then the resist film is used as a mask. Then, the gate electrode 2 and the storage capacitor lower electrode 3 are formed by etching.

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

In FIG. 5B, patterning is performed so that the channel protection film 6 immediately above the gate electrode 2 remains. Figure 5
In (C), n ⁺ type a-Si is used as a contact layer on the substrate.
The layer 7 and the source / drain electrode metal film 8 are continuously formed.

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

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

[0011]

The second insulating film 9 is formed to a thickness of 3000 to 4000 Å, but the film quality varies greatly 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 cross-sectional shape of the contact hole can be a forward taper, a vertical taper or a reverse taper, as shown in FIG. In the case of the forward taper, there is no particular problem, and when the ITO film 11 is formed, it is possible to make contact with the storage capacitor upper electrode and the source electrode through the contact hole, but in the case of the reverse taper, it is possible to make contact. Instead, it becomes a display defect.

The second insulating film 9 is monosilane (SiH
₄ ) and ammonia (NH ₃ ) are used as the main raw materials to form a film in a strong reducing atmosphere, so even if a small amount of metal compound contamination remains on the substrate, it will be reduced and conductive foreign matter will be generated. . As a result, the surface of the substrate sometimes became conductive.

It is an object of the present invention to improve the reliability of the device and the manufacturing yield by making the contact hole formed in the second insulating film into a forward tapered shape and preventing conduction on the substrate surface in the manufacture of the TFT device. .

[0014]

[Means for Solving the 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, 4 The step of sequentially forming the semiconductor layer 5 and the channel protective film 6, and then the step of patterning the channel protective film so as to leave the channel protective film directly above the gate electrode, and then the high concentration on the substrate. A step of sequentially forming a contact layer 7 made of a semiconductor and a metal film 8 for source / drain electrodes,
Next, the contact layer and the source / drain electrode metal film 8 are patterned 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, then a step of forming a contact hole in the second-layer insulating film on the source electrode and the storage capacitor upper electrode, and then 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. Manufacturing method, or 2) The method for manufacturing a thin film transistor matrix according to 1), wherein the second insulating film 9 is a thermosetting resin, a photocurable 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 instead of CVD SiN as the second insulating film. This is the result of the present inventor confirming that the resin film can be stably applied and formed without the reverse taper being formed without variation in the cross-sectional shape of the contact hole depending on the film forming conditions found in the P-CVD method. Is used.

Further, since it is a resin, the residue of the metal compound is not reduced, and the resin surface is flattened due to the spin coating.

[0017]

EXAMPLE Example (1): FIGS. 1 (A) to 1 (F) are sectional views of Example (1) of the present invention.

In FIG. 1 (A), a glass substrate 1 as a transparent insulating substrate is sputtered with a thickness of 1000 Å of Al.
The film and a Cr film with a thickness of 1000 Å are continuously formed, and after patterning the resist film by photolithography, the resist film is used as a mask for etching to form the gate electrode 2 and the storage capacitor lower electrode 3.

Next, the resist film is peeled off, and a P-CVD method is used to form a gate insulating film as the first insulating film and a silicon nitride (SiN) film having a thickness of 4000 Å as a storage capacitor dielectric film.
4. A 150-Å-thick a-Si film 5 as an operating semiconductor layer 5 and a 1200-Å-thick SiN film 6 as a channel protective film are continuously grown.
Here, as the first insulating film, an alumina film formed by the ALD method may be used instead of the SiN film 4.

In FIG. 1B, patterning is performed so as to leave the channel protective film 6 directly above the gate electrode 2. Figure 1
In (C), the thickness of the contact layer on the substrate is 600Å
The n ⁺ type a-Si layer 7 and the metal film 8 for source / drain electrodes, which is made of a chromium (Cr) film having a thickness of 1500 Å, are continuously formed.

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

In FIG. 1 (E), a transparent thermosetting resin film is applied as the second insulating film 9 and cured (heat treatment).
I do. As the thermosetting resin, for example, a silicon-based or epoxy-based thermosetting resin is used, which 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 openings on the source electrode and the storage capacitor is formed on the substrate by photolithography. In FIG. 1F, the thermosetting resin film is etched using the resist film 10 as a mask to form contact holes, and the resist film 10 is removed. At the same time, the resin on the connection terminals is also removed by etching.

Next, a pixel electrode film having a thickness of 700 is formed on the resin.
Å ITO film is formed, contact is made to the storage capacitor upper electrode 8C and source electrode 8S, and patterning is performed.
11 to form a TFT matrix.

Example (2): In Example (1), a transparent thermosetting resin film was used as the second insulating film 9, but instead of this, a photo-setting resin, for example, a UV resin was used. Use, Example
The film may be formed in the same manner as (1).

Embodiment (3): FIG. 2 is a sectional view of an embodiment (3) of the present invention. A photosensitive resin, such as a photosensitive polyimide resin, is used as the second layer insulating film 9, and the photosensitive polyimide resin is patterned using a photomask 12 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, the transparent resin film 9 of the present invention or the SiN film 14 of the conventional example is used as the second insulating film for the TFT.
After forming, the transparent insulating film is formed as the protective film 13 on the surface of the substrate. At this time, do not form a protective film on the connection terminals. Alternatively, the film may be formed or may be removed by etching after that. The surface of the substrate is flattened by the protective film 13, and the next step can be performed accurately.

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 the film formation device is simple and compact. Further, when a photosensitive resin is used, the resist coating step can be omitted. (2) Since the resin film formation conditions are stable, it is possible to eliminate the conventional inverse 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, the reduction of the metal oxide residue is eliminated and conduction on the substrate surface can be prevented. (4) Since the resin film is applied by spin coating, the substrate surface can be flattened. (5) Reliability and manufacturing yield are improved, and cost reduction can be realized.

[0029]

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

[Brief description of 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.

[Figure 4] Plan view of the TFT matrix

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

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

[Explanation of symbols]

1 Transparent insulating substrate, glass substrate 2 Gate electrode 3 Storage capacitor lower electrode 4 First layer insulating film (gate insulating film and storage capacitor dielectric film) SiN film 5 Operating semiconductor layer a-Si film 6 Channel protective film With SiN film 7 n ⁺ type a-Si layer with contact layer 8 metal film for source / drain electrode 8D drain electrode 8S source electrode 8C storage capacitor upper electrode 9 second layer insulation film transparent resin film 10 resist film 11 pixel electrode ITO film

Claims (3)

[Claims] 1. A gate electrode on a transparent insulating substrate (1)
(2) and storage capacitor lower electrode (3) are formed, on which the first insulating film (4), operating semiconductor layer (5), channel protective film (6)
And a step of patterning the channel protective film so as to leave the channel protective film directly above the gate electrode, and then a contact layer (7) made of a high-concentration semiconductor on the substrate. And a source / drain electrode metal film (8) in that order, and then patterning the contact layer and the source / drain electrode metal film,
Step of forming drain electrode (8D), source electrode (8S) and storage capacitor upper electrode (8C), and then depositing a second layer insulating film (9) made of transparent resin on the substrate And a step of forming a contact hole in the second-layer insulating film on the source electrode and the storage capacitor upper electrode,
Then, a transparent electrode film is formed on the substrate, the storage capacitor upper electrode and the source electrode are contacted with the transparent electrode film, and the transparent electrode film is patterned to form a pixel electrode (11).
And a step of forming a thin film transistor matrix. 2. The method of manufacturing a thin film transistor matrix according to claim 1, wherein the second insulating film (9) is a thermosetting resin, a photocurable resin or a photosensitive resin. 3. A method of manufacturing a thin film transistor matrix, comprising a step of forming a transparent insulating film so as to cover a pixel electrode (11) formed on a transparent insulating substrate (1).