JPH03136240A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To facilitate the formation of fine patterns and to make it possible to etch correctly an Al film as the fine patterns are formed by a method wherein the surface of the Al film is fluorinated according to a desired etching pattern and a dry etching is performed on the Al film using the fluorinated Al film as a mask. CONSTITUTION:When an Al film 12 applied to a semiconductor substrate 10 is selectively removed by etching, the surface of the film 12 is fluorinated according to a desired etching pattern and a dry etching is performed on the film 12 using the fluorinated Al film 14 as a mask. For example, resist patterns 13 of a thickness of 2000 to 3000Angstrom are formed on the surface of an Al film 12, the sample is exposed to the mixed gas of 95% of Ar gas and 5% of ClF3 gas and an AlF3 film 14 is formed on the exposed surface of the film 12. Then, the patterns 13 are removed by an oxygen plasma treatment and after an etching of the film 12 is performed by an RIE method using chlorine gas, such as CCl4 gas and the like, using AlF3 patterns 14a as masks, the left AlF3 film is removed by a wet treatment using water.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to a method for manufacturing a semiconductor device, and more specifically,
This invention relates to a method for selectively etching away an aluminum (An) film deposited on a semiconductor substrate.

(b) Prior Art FIG. 2 shows the steps of a selective etching method for a /l film that has been commonly used in the past (see, for example, Japanese Patent Laid-Open No. 183929/1983).

First, a pattern (3) is formed with a resist having a thickness of about 1 μm or more on the surface of a ρ film (2) formed on a semiconductor substrate (1) (FIG. 2a).

Using the formed thick resist pattern (3) as an etching mask, the exposed i-film (2) is etched by reactive ion etching (RIE) using a chlorine-based gas such as carbon tetrachloride (CC42a). (Figure 2b).

After etching of the At2 film by RIE is completed, the resist pattern (3) used as an etching mask is removed by dry processing using oxygen plasma or wet processing using an organic solvent (FIG. 2C).

In this way, an etching pattern for the AR film (2) is obtained.

(c) Problems to be Solved by the Invention In the conventional method using a resist as an etching mask, R
When etching an AN film by IE, the selectivity (difference in etching resistance) between At) and the resist is small, so the resist pattern used as an etching mask is required to have a sufficient thickness. However, when the resist used as an etching mask becomes thick, it not only becomes difficult to form a fine resist pattern, but also it becomes difficult to accurately etch one film according to the fine pattern of the resist.

The present invention has been made in view of this point.

(d) Means for Solving the Problems The method for manufacturing a semiconductor device according to the present invention includes the steps of selectively etching away an Ag film deposited on a semiconductor substrate.
The surface of the AN[ is fluorinated according to a desired etching pattern, and the above 11151 is dry etched using the aluminum fluoride as a mask.

(e) Function Ag fluoride has sufficient dry etching resistance, so it can be used as an etching mask with a thin film thickness.

Since the thickness of the AR fluoride serving as an etching mask can be made thin, it is easy to form a fine pattern, and the A& film can be etched accurately in accordance with the fine pattern of the thin fluoride.

(f) Example FIG. 1 is a process diagram showing an example of the method for selectively etching an Ag film according to the present invention.

A film was formed on a semiconductor substrate (10) such as St. III
A fine resist pattern (13) with a thickness of about 2,000 to 3,000 layers is formed on the surface of I (12) (FIG. 1a).

This sample is placed in a chamber and evacuated to a vacuum before introducing gas. Ar95% Chlorine trifluoride (Ca
F2) Introduce 5% mixed gas into the chamber and
When the flow continues under Torr pressure, the resist pattern (
13) CNF and Ag on the surface of the Ag film not covered with
Aluminum fluoride (A OF3) is a reaction product of
(14) is deposited in about 1000 people in 2 minutes (Fig. 1b
).

Here, the resist pattern (
When 13) is removed, a fine pattern (14a) of AfF with a thickness of about 1000 nm remains on the surface of the Af film (FIG. 1C).

Using this iF fine pattern (14a) as an etching mask, perform RIE using a chlorine gas such as CCI a.
The AN film (12) is etched by (Fig. 1d)
).

AfFi has dry etching resistance, so
It can be used as a mask for about 0,000 people with a thickness of 0.

Furthermore, iF has the property of being almost insoluble in solvents other than water, so A#jl! by RIE! After etching is completed, the remaining A OF 3 can be easily removed by wet treatment with water (Fig. 1e).
.

In the manner described above, a fine etching pattern of the Ag film can be formed.

(g) Effects of the invention According to the present invention, it is possible to produce finer patterns than conventional methods.
G film can be etched.

Further, since ARP, which serves as a mask, is soluble only in water, it is very easy to remove AgF after etching the Ag film, and moreover, it does not damage the underlying semiconductor substrate.

Claims (1)

[Claims] (1) When selectively etching and removing an aluminum film deposited on a semiconductor substrate, the surface of the aluminum film is fluorinated according to a desired etching pattern, and the aluminum film is etched using this aluminum fluoride as a mask. 1. A method of manufacturing a semiconductor device, comprising performing dry etching on a semiconductor device.