JP2000208474A - Pattern forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent oxidation of the surface of a polysilicon thin film used for a liquid crystal display element, etc., and occurrence of etching residues when a pattern such as TFT, etc., is formed on the polysilicon thin film. SOLUTION: After a polysilicon thin film 2 is formed on the entire surface, backside and side face of an insulating substrate 1, a resist 3 is coated on the polysilicon thin film 2 formed on the surface of the insulating substrate 1. Subsequently, the insulating substrate in this state is placed on a hot plate 4 and subjected to a thermal treatment at a temperature as low as 90 deg.C. Then, the polysilicon thin film 2 on the backside and side face is etched by using the resist 3 as a mask and thereafter the resist 3 is removed by using a thinner 9. Finally, a pattern 5 such as TFT, etc., is formed on the polysilicon thin film 2 by photoetching, etc. By this process, oxidation of the surfaces of the polysilicon thin film can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film transistor (hereinafter, referred to as a TFT) using a polysilicon thin film on an insulating substrate.
The present invention relates to a pattern forming method for forming a suitable pattern when forming a pattern.

[0002]

2. Description of the Related Art When manufacturing a liquid crystal panel using a TFT circuit using an insulating substrate or the like, a high transmittance is required.
It was necessary to remove the polysilicon thin film formed on the back surface of the insulating substrate.

A conventional pattern forming method for removing a polysilicon thin film formed on the back surface of an insulating substrate to form a pattern such as a TFT on the surface of the insulating substrate will be described with reference to FIG.

[0004] First, a polysilicon thin film 2 is formed on the entire front, back and side surfaces of a transparent insulating substrate 1 (FIG. 2).
a).

Next, a resist 3 is applied on the polysilicon thin film 2 formed on the surface of the insulating substrate 1 (FIG. 2).
b).

Subsequently, the insulating substrate in this state is placed on the hot plate 4 and heat-treated at a temperature of 200 ° C. (FIG. 2C).

Then, using the resist 3 as a mask, the polysilicon thin film 2 is etched by wet etching for 150 seconds to remove the polysilicon thin film 2 formed on the back and side surfaces of the insulating substrate 1. Subsequently, the surface resist 3 is removed over 70 minutes using oxygen plasma (FIG. 2D).

Finally, a pattern 5 such as a TFT is formed on the surface of the polysilicon thin film 2 by photolithography or the like (FIG. 2E).

[0009]

In the conventional pattern forming method, as shown in FIG. 2C, immediately after the resist 3 is applied on the polysilicon thin film 2 on the surface of the insulating substrate 1, a high temperature of 200.degree. When the heat treatment is performed, bubbles 6 are generated in the resist 3, and through holes are formed by the bubbles 6. When the polysilicon thin film 2 on the back surface in the next step is etched, the etchant and the water for washing thereafter penetrate. When the etchant permeates, the polysilicon thin film 2 is etched to form pinholes and the like.
Moreover, when water permeates, it is easily oxidized.

After that, by applying oxygen plasma for 70 minutes to remove the resist 3, as shown in FIG. 2d, the surface of the local polysilicon thin film 2 where the bubbles 6 are generated is oxidized, and the oxide film 7 is formed. it can. Therefore, in the next step of forming a pattern 5 such as a TFT, FIG.
As shown in the figure, the area that must be separated
The oxide film 7 causes the polysilicon thin film 2 therebelow to be present as the etching residue 8, which causes a problem that a short circuit between the patterns 5 occurs.

The present invention provides a method for forming a pattern capable of preventing local pinholes and oxidation of a polysilicon thin film.

[0012]

According to the present invention, there is provided a pattern forming method comprising: forming a polysilicon thin film on the entire surface of a front surface, a back surface, and side surfaces of an insulating substrate; and forming the polysilicon film on the surface of the insulating substrate. A heat treatment step of applying a resist on the silicon thin film and baking it at 80 to 100 ° C .; and an etching step of etching the polysilicon thin film formed on at least the back surface of the insulating substrate subjected to the heat treatment step.

Accordingly, since the resist is heat-treated at a low temperature of 80 to 100 ° C., no bubbles are generated in the resist. For this reason, even if the polysilicon thin film on the back surface of the insulating substrate is etched, an etching area such as a pinhole cannot be formed in the polysilicon thin film on the front surface of the insulating substrate. can do.

Further, in the pattern forming method according to the present invention, after the etching step, a resist removing step of removing the resist applied to the surface of the polysilicon thin film with a thinner, and selectively etching the polysilicon thin film. A pattern forming step of forming a pattern using the polysilicon thin film.

[0015] As a result, since the resist is further removed using a thinner having no oxygen component, even if bubbles are formed in the resist, local oxidation of the polysilicon thin film by the bubbles can be prevented. Even during pattern formation, etching residue can be prevented.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the pattern forming method of the present invention will be described below with reference to the drawings.

FIG. 1 is a process sectional view showing a pattern forming method of the present invention.

First, a polysilicon thin film 2 is formed on the entire surface of the front, back and side surfaces of the insulating substrate 1 by a low pressure CVD method (FIG. 1A).

Next, a resist 3 is applied on the polysilicon thin film 2 formed on the surface of the insulating substrate 1 (FIG. 1).
b).

Subsequently, the insulating substrate 1 coated with the resist 3
Is placed on a hot plate 4 and heat-treated at a low temperature of 90 ° C. for 60 seconds (FIG. 1c). The heat treatment temperature is 90 ° C.
However, the temperature may be 80 to 100 ° C. If the temperature is lower than 80 ° C., the resist 3 cannot be hardened sufficiently. Also,
When the temperature is 100 ° C. or higher, bubbles are easily generated.

Thereafter, using the resist 3 as a mask, the polysilicon thin film 2 on the back and side surfaces is etched and removed. Further, the thinner 9 is blown out from the thinner nozzle 10 to remove the resist 3 applied on the surface (FIG. 1d).

Finally, a pattern 5 such as a TFT is formed on the surface of the polysilicon thin film 2 by photolithography or the like (FIG. 1e).

According to the above pattern forming method, first,
After applying the resist 3 on the polysilicon thin film 2, 90
Since the heat treatment is performed on a hot plate at a low temperature of 0 ° C., no bubbles are generated in the resist 3. Therefore, even if the polysilicon thin film 2 on the rear surface is subsequently etched, an etched region such as a pinhole does not occur in the polysilicon thin film 2 on the front surface.

Further, since the resist 3 is thereafter removed by a thinner having no oxygen component, even if bubbles are present, local oxidation on the surface of the polysilicon thin film can be prevented. In addition, pattern defects can be eliminated.

[0025]

According to the pattern forming method of the present invention, no bubbles are generated in the resist used as a mask for removing the polysilicon thin film on the back surface, so that the polysilicon thin film on the front surface is etched when the polysilicon thin film on the back surface is removed. Since a region cannot be formed and local oxidation of the polysilicon thin film can be prevented, a pattern without etching unevenness can be formed at the time of pattern formation, and a short circuit failure between patterns can be eliminated.

[Brief description of the drawings]

FIG. 1 is a process sectional view showing a pattern forming method of the present invention.

FIG. 2 is a process sectional view showing a conventional pattern forming method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating substrate 2 Polysilicon thin film 3 Resist 4 Hot plate 5 Pattern 6 Bubbles 7 Oxide film 8 Unetched residue 9 Thinner 10 Thinner nozzle

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toshihide Shinsada 1-1, Komachi, Takatsuki-shi, Osaka Matsushita Electronics Co., Ltd. F-term (reference) 5F043 AA07 AA08 AA09 AA10 BB03 GG10 5F046 JA22 MA02 MA18 5F110 CC01 GG02 GG13 GG47

Claims (2)

[Claims] A film forming step of forming a polysilicon thin film on the entire surface of a front surface, a back surface and side surfaces of an insulating substrate; and applying a resist on the polysilicon thin film formed on the surface of the insulating substrate; A pattern forming method, comprising: a heat treatment step of baking at 100 ° C .; and an etching step of etching the polysilicon thin film formed on at least the back surface of the insulating substrate subjected to the heat treatment step. 2. After the etching step, a resist removing step of removing the resist applied to the surface of the polysilicon thin film with a thinner, and selectively etching the polysilicon thin film to form a pattern of the polysilicon thin film 2. The pattern forming method according to claim 1, further comprising a pattern forming step.