JPS63226930A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form a fine submicron pattern by using an exposure technique by means of the ordinary light by a method wherein a film to be processed is etched by using a mask in the form of a side wall which is formed on the side wall at an intermediary layer by a reactive ion etching method. CONSTITUTION:An intermediary layer 3 composed of a material which is different from that of a film 2 to be processed is formed on the film 2, to be processed, which has been formed on a semiconductor substrate 10; a part on the surface of the intermediary layer 3 is removed by an isotropic etching method by making use of a photoresist 4 as a mask; in succession, the remaining intermediary layer 3 is etched by an anisotropic etching method; at the same time, a reaction product film 5 is formed on the side of the intermediary layer 3. Then, said mask 4 and the intermediary layer 3 situated under the mask are removed; after that, the film 2 to be processed is etched by the anisotropic etching method by making use of the reaction product film 5 as a mask. For example, an aluminum film 3 is applied to a polysilicon film 2; the polysilicon film 2 at an unnecessary part is removed by a reactive ion etching method by using a mask in the form of a side wall 5 which is composed of a reaction product produced by the reactive ion etching method.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of forming a fine pattern.

[Conventional technology]

Conventionally, a common method for patterning a film to be processed formed on a semiconductor substrate is to form a desired pattern using a photoresist, and then remove the film to be processed using this as a mask. Next, an example of patterning a polysilicon film by a conventional manufacturing method will be explained using FIGS. 3(a) to 3(C).

First, as shown in FIG. 3(a), a polysilico film 2 is deposited on an underlying oxide film 1, and a mask is formed using a photoresist 4. Then, as shown in FIG.

Next, as shown in FIG. 3(b), unnecessary portions of the polysilicon film 2 are removed by reactive ion etching (RIE) using CCJ'2Fz gas. At this time, sidewalls 5B made of reaction products adhere to the sidewalls of the polysilicon film.

Thereafter, as shown in FIG. 3(C), the photoresist 4 and sidewall 5B are removed using an organic solvent, thereby completing the patterning of the polysilicon M2.

[Problem that the invention seeks to solve]

In the conventional pattern forming method described above, the film to be processed is processed according to a mask made of photoresist, so “
The minimum width of the pattern is determined by the width of the mask. In current optical photoresist exposure methods, the minimum width of the mask is
The limit is approximately 1 μm, and it is difficult to form a submicron mask. Therefore, there is a drawback that it is difficult to pattern the processed film to a submicron width.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a semiconductor device that eliminates the above-mentioned drawbacks and can process a film to be processed with a submicron width.

[Means for solving problems]

The method for manufacturing a semiconductor device of the present invention includes the steps of forming an intermediate layer made of a material different from that of the film to be processed on a film to be processed formed on a semiconductor substrate, and forming an isotropic layer using a photoresist as a mask. a step of removing a part of the surface of the intermediate layer by an etching method and then etching the remaining intermediate layer by an anisotropic etching method and forming a reaction product film on the side surface of the intermediate layer; After the layer is removed, the film to be processed is etched by an anisotropic etching method using the reaction product film as a mask.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIGS. 1(a) to 1(e) are cross-sectional views of a semiconductor chip shown in order of steps for explaining a first embodiment of the present invention.

First, as shown in FIG. 1(a), a polysilicon film 2, which is a workpiece, is deposited on a semiconductor substrate 10 via an underlying oxide film 1, and an aluminum film 3, which is an intermediate layer, is deposited. Next, a mask made of photoresist 4 is formed.

Next, as shown in FIG. 1(b), a part of the surface of the aluminum film 1 is removed using hot phosphoric acid.

Next, as shown in FIG. 1(c), unnecessary portions of the aluminum film 3 are removed by reactive ion etching using BCf2+CC24 gas.

At this time, a sidewall 5 made of a reaction product is attached to the sidewall of the aluminum film 3. However, since aluminum has been removed near the interface between the side wall portion of the aluminum film 3 and the photoresist 4, the side fall 5 does not adhere thereto.

The main component of this sidewall 5 is photoresist, and is formed by redepositing photoresist that has been etched by accelerated ions. Therefore, the amount of sidewall 5 to be deposited is determined by the etching acceleration voltage and gas type. In the first embodiment, B C! is used as the reactant gas. ! 3 + CCl 4 was used, but
Equivalent substances are also formed with fBce+C12CCe4 and S iCj'4.

Next, as shown in FIG. 1(d), the aluminum film 3 is removed using hot phosphoric acid. At this time, the photoresist 4 on the aluminum film 3 is also removed at the same time.

Next, as shown in FIG. 1(e), unnecessary portions of the polysilicon film 2 are removed by reactive ion etching using, for example, CCj'2Fz gas, and then the sidewalls 5 are removed by oxygen plasma etching. By removing it, a fine pattern 2A made of a polysilicon film is formed.

FIGS. 2(a) to 2(e) are cross-sectional views of a semiconductor chip shown in order of steps for explaining a second embodiment of the present invention.

First, as shown in FIG. 2(a), an aluminum film 3 as a workpiece and a nitride film 13 as an intermediate layer formed by plasma CVD are deposited on a semiconductor substrate 10 via an underlying oxide film 1.
A mask made of photoresist 4 is formed.

Next, as shown in FIG. 2(b), a portion of the nitride film 13 is removed by isotropic plasma etching using CF4+02 gas.

Next, as shown in FIG. 2(c), unnecessary portions of the nitride film 13 are removed by reactive ion etching using CF 4 + 82 gas.

Thereafter, as shown in FIG. 2(d), the nitride film 13 is removed by isotropic plasma etching using CF 4 + 02 gas. At this time, a sidewall 5A made of a reaction product is formed on the sidewall of the nitride film 13.

Next, as shown in FIG. 2(e), using this sidewall 5A as a mask, reactive ion etching is performed using B Ce 3 + CCj' 4 gas to remove unnecessary portions of the aluminum film 3, and then By removing the sidewall 5A using 02 plasma, a fine pattern 3A made of an aluminum film is formed.

〔Effect of the invention〕

As explained above, the present invention etches the film to be processed using the sidewalls formed on the sidewalls of the intermediate layer as a mask by reactive ion etching. The effect of forming patterns increases.

[Brief explanation of the drawing]

1(a)-(e) and FIG. 2(a)-(e) are cross-sectional views of a semiconductor chip shown in the order of steps for explaining the first and second embodiments of the present invention; Figures (a) to (C) are cross-sectional views for explaining a conventional method of manufacturing a semiconductor device. 1... Oxide film, 2... Polysilicon film, 2A...
Fine pattern, 3... Aluminum film, 3A... Fine pattern, 4... Photoresist, 5.5A, 5B
...Side wall, 10...Semiconductor substrate, 13.
...Nitride film. Cow 1 diagram

Claims (1)

[Claims] A step of forming an intermediate layer made of a material different from that of the film to be processed on a film to be processed formed on a semiconductor substrate, and a step of forming a part of the surface of the intermediate layer by isotropic etching using a photoresist as a mask. and then etching the remaining intermediate layer using an anisotropic etching method and forming a reaction product film on the side surfaces of the intermediate layer, and removing the mask and the intermediate layer below the mask, and then etching the remaining intermediate layer using an anisotropic etching method. A method of manufacturing a semiconductor device, comprising the step of etching the film to be processed by an anisotropic etching method using as a mask.