JPH03108330A - Manufacture of semiconductor - Google Patents

Abstract

PURPOSE:To form a desired pattern in which etching residue of a level-difference part is not left by a method wherein, after the film thickness of material to be etched is uniformized by previously etching only the level-difference part, the flat part is etched. CONSTITUTION:After a polysilicon film 2 and a silicide film 3 are formed on a silicon substrate 1, an etching-resistant coating film 5 is formed, and a level- difference part only is exposed. Further a resist pattern for forming a gate is formed by using a resist layer 4. The film 5 is used as a mask, and the level-difference part is etched by anisotropic etching. The level-difference part only is subjected to a desired amount of etching under the condition that the film 5 except the part under the desired resist pattern is eliminated by a selection ratio of the film 3 and the film 5. The flat part whose film thickness has become uniform except a gate forming part as the result of the anisotropic etching is subjected to just-etching, thereby preventing the etching residue generated at the level-difference part.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a semiconductor device, and in particular to a method for effectively etching away material to be etched on a stepped portion of a semiconductor device.
The present invention relates to a method for performing anisotropic etching.

[Conventional technology]

FIGS. 2a to 2b are cross-sectional views showing the main steps of a conventional method for manufacturing a semiconductor device.

In the figure, 1 is a semiconductor substrate, 2 is a polysilicon film, and 3 is a semiconductor substrate.
is a silicide film such as Mo, 4 is a resist film, and 7 is a silicide film such as Mo.
is the etching residue. FIG. 2a is a cross-sectional view showing a polysilicon film 2 and a silicide film 3 made of Mo or the like formed to form a desired resist pattern, and FIG. 2a is a cross-sectional view after etching. .

Next, a conventional manufacturing method will be explained. Here, a method for forming the gate portion will be particularly described.

First, after going through steps such as forming a well in a silicon substrate 1, a polysilicon film 2 is formed, and then a silicide M3, which is a material for a gate electrode, is formed. Thereafter, a resist film 4 is applied and a desired resist pattern is formed by exposure and development steps. Further, using the resist pattern as a mask, etching is performed to form the gate portion 6. At this time, since highly accurate dimensional control is required, anisotropic etching such as reactive ion etching (RIE) is performed.

In this way, a gate pattern with a smaller shift amount than the resist pattern is obtained.

[Problem to be solved by the invention]

Since the conventional semiconductor device manufacturing method is configured as described above, polysilicon llI2.
Since the film thickness of the silicide film 3 and the like becomes thick, etching residue 7 is generated when anisotropic etching that progresses uniformly on the substrate surface is performed.

In order to remove this etching residue 7, methods such as additional etching and wet etching are used, but there are problems such as damage to the film base and side etching that makes it difficult to control the dimensions of the desired pattern.

This invention has been made to solve the above-mentioned problems, and provides a method for manufacturing a semiconductor device that eliminates etching residue at stepped portions, enables highly accurate dimensional control, and obtains a desired pattern. The purpose is to

[Means to solve the problem]

A method for manufacturing a semiconductor device according to the present invention is a method for forming a desired pattern by photolithography and etching on an insulating film, a conductive film, etc. formed on a semiconductor substrate. A method for manufacturing a semiconductor device, which comprises forming an etching-resistant film that exposes only the material, pre-etching a desired amount of the material to be etched on the stepped portion, and then forming a desired pattern with a resist and etching.

[Effect]

In the method of manufacturing a semiconductor device of the present invention, an etching-resistant film is formed that exposes only the step portion, and the film thickness of the material to be etched is made uniform by performing preliminary etching. Thereafter, by etching the flat portions, it is possible to obtain a desired pattern without etching residues on the stepped portions.

〔Example〕

Hereinafter, an embodiment of the present invention will be explained with reference to FIG.
5 is an etching-resistant coating.

Next, the manufacturing method will be explained. Here, a method for forming a gate portion will be described as an example, similar to the conventional method.

First, as shown in FIG. 1a, after forming a polysilicon film 2 and a silicide film 3 on a silicon substrate 1, an etching-resistant film 5, such as a thin resist film, is applied and formed.
Expose only the step part.

Furthermore, a resist pattern is formed using the resist film 4 to form a gate.

Next, as shown in FIG.
Anisotropic etching is performed using the mask as a mask, and only the exposed step portions are etched. Here, depending on the selectivity between the silicide film 3 and the etching-resistant film 5, which is the first thin resist film, only the stepped portion is etched by a desired amount while removing the etching-resistant film other than under the desired resist pattern.

Furthermore, as shown in FIG. 1C, anisotropic etching is carried out to just etch the flat part, which has a uniform film thickness, except for the resist pattern part for forming the gate.

According to the above embodiment, since only the step portion is etched in advance, it is possible to prevent etching residues from being generated at the step portion due to anisotropic etching.

〔Effect of the invention〕

As described above, according to the present invention, only the stepped portions are exposed and etched first, and then the flat portions are etched, thereby preventing etching residues caused by just etching and eliminating the need for side etching by additional etching or wet etching. This enables highly accurate dimensional control.

[Brief explanation of drawings]

FIGS. 1a-c are sectional views showing main steps of a method for manufacturing a semiconductor device according to an embodiment of the present invention, and FIGS. 2a-b are sectional views showing a conventional method for manufacturing a semiconductor device. In the figure, 1 is a semiconductor substrate, 2 is a polysilicon film, 3 is a silicide film, 4 is a resist film, and 5 is an etching-resistant coating. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] In a semiconductor device manufacturing method in which a desired pattern is formed by performing photolithography and etching on an insulating film or a conductive film formed on a semiconductor substrate, an etching-resistant film that exposes only the material to be etched in the stepped portion is used. 1. A method of manufacturing a semiconductor device, comprising: forming a semiconductor device and pre-etching a desired amount of a material to be etched in a stepped portion, and then forming a desired pattern using a resist and etching.