JPS61113260A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enable to prevent disconnection by making the section with a gentle inclination in the first silicon dioxide film by a method wherein, after the first silicon dioxide film is formed by a vapor deposition method, a heat treatment is performed, the second silicon dioxide film is formed on the first silicon dioxide film and after an opening is simultaneously provided on the first and second silicon dioxide films, the second silicon dioxide film is removed. CONSTITUTION:A silicon dioxide film 4 is formed on a silicon substrate 1 by a normal pressure vapor deposition method, and after that, a heat treatment is performed in an atmosphere of nitrogen. Then, a silicon dioxide film 2 is made to deposit on the film 4 by a normal pressure vapor deposition method in the same way. After that, a photo resist 3 is applied and an opening is simultaneously provided on the films 4 and 2. When an etching is performed on the films 2 and 4 using a mixing solution of hydrofluoric acid and ammonium fluoride, the heat treatment finished film 4 is formed so as to have a gentle inclination. After the photo resist 3 is removed, the upper silicon dioxide film 2 is removed. Lastly, an aluminum film 5 is made to adhere and when the film 5 is used as the wiring layer, no disconnection occurs and the manufacturing yield of the semiconductor device can be made to improve significantly, because the inclination of the film 4 is gentle.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a semiconductor device that can be used in the manufacturing process of semiconductor integrated circuits.

Conventional configurations and their problems In recent years, semiconductor integrated circuits have tended to have higher densities and higher performance, and as a result, expectations and demands for the development of fine pattern forming methods have increased. Conventionally, fine patterns have been formed using silicon oxide films in semiconductor integrated circuits, but the etching of the 71-layer oxide film has resulted in steep unevenness, which has caused disconnections in interconnections.
In compound semiconductor devices such as gallium sulfide integrated circuits, decomposition of the substrate occurs during heat treatment.

Hereinafter, a conventional method for manufacturing a semiconductor device as described above will be described with reference to the drawings.

FIG. 1 shows an insulating film etching method among conventional semiconductor device manufacturing methods. In FIG. 1, 1 is a silicon substrate on which an integrated circuit is fabricated. 2 is a silicon dioxide film provided on a silicon substrate; 3 is a photoresist for printing a fine pattern of an integrated circuit onto the silicon dioxide film 2;

Regarding the method for manufacturing a semiconductor device as described above, first, a silicon dioxide film 2 is formed on a silicon substrate 1 as shown in FIG. 1 (al). A photoresist 3 is applied to the film, exposed and developed. Next, the silicon dioxide film 2 is etched as shown in FIG. Etching of the silicon film 2 is completed.

However, in the above structure, the etched cross section of the silicon dioxide film 2 becomes steep as shown in FIG. It has a drawback that when another insulating film is formed on top of it, the covering property of the film deteriorates.

SUMMARY OF THE INVENTION An object of the invention is to provide a method of manufacturing a semiconductor device that can be improved.

Structure of the Invention To achieve this object, the method for manufacturing a semiconductor device of the present invention includes a first silicon dioxide film forming step by chemical vapor deposition, a first silicon dioxide film heat treatment step, and a first silicon dioxide film forming step. It consists of a step of forming a second silicon dioxide film on the film using the same method, a step of simultaneously etching the first and second silicon dioxide films, and a step of removing the second silicon dioxide film. It is possible to create a cross-section with a wide cross-section and prevent wire breaks that occur during wiring. Furthermore, it is possible to improve coverage when an insulating film is formed thereon.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows the manufacturing steps of the method for manufacturing a semiconductor device according to the first embodiment of the present invention. In Figure 2,
1 is a silicon substrate, 2 is an unheated silicon dioxide film,
3 is a 7-photoresist, 4 is a heat-treated silicon dioxide film, and 5 is an aluminum wiring.

The operation of the method for manufacturing the semiconductor device configured as described above will be described below. First, a silicon dioxide film 4 of 6Q0〇 is formed on a silicon substrate 1 by atmospheric pressure chemical vapor deposition.
After forming, heat treatment was performed at 500° C. for 1 hour in a nitrogen atmosphere. Next, heat-treated silicon dioxide film 4
A silicon dioxide film 2 of 1,000 layers was deposited thereon by the same atmospheric pressure chemical vapor deposition method. Thereafter, photoresist 3 was applied and holes were opened in the photoresist 3 as shown in Figure 2 (al).
When the silicon dioxide films 2 and 4 are etched with the mixed solution, the heat-treated silicon dioxide film 4 has a gentle slope as shown in FIG. 2 (bl).

This occurs because the etching rate of the atmospheric pressure silicon dioxide film 20 with respect to the hydrofluoric acid/ammonium fluoride mixed solution is reduced by the heat treatment as shown in FIG. In other words, the etching rate of the upper silicon dioxide film 2 without heat treatment is 0.7 μV, whereas that of the lower silicon dioxide film 4 with heat treatment is 0.45 μm/min.
Therefore, while the lower silicon dioxide film 4 is being etched, the lateral etching of the upper silicon dioxide film 2 progresses, resulting in a gently sloped cross section. However, since the etched cross section of the upper silicon dioxide film 2 becomes steep, if the upper silicon dioxide film 2 is removed after the photoresist 3 is removed, the etched cross section of the upper silicon dioxide film 2 is etched as shown in FIG. membrane 4
only remains.

Finally, when aluminum 5 is deposited and used as a wiring, the etched cross section of the silicon dioxide film 4 is gentle, so no disconnection occurs here, and the yield of integrated circuits can be greatly improved. As described above, according to this embodiment, the silicon dioxide film is changed from the conventional single-layer structure to a two-layer structure consisting of the silicon dioxide film 4 subjected to heat treatment and the silicon dioxide film 2 not subjected to heat treatment. By utilizing the difference in the etching speed of the underlying silicon dioxide film, it is possible to create an etched cross section with a gentle slope, making it possible to prevent disconnection of the aluminum wiring a6.

A second embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 shows a manufacturing process of a method for manufacturing a semiconductor device according to a second embodiment of the present invention.

In the figure, 6 is a gallium arsenide substrate on which an integrated circuit is made, and 7 is a silicon nitride film used as a cap during activation after ion implantation.

The operation of the method for manufacturing the semiconductor device configured as described above will be described below. Figure 4 (from a+ Figure 4 (
The process of giving a gentle etching cross section to the silicon dioxide film on the gallium arsenide substrate 6 up to Cl is exactly the same as in the first embodiment.

Thereafter, silicon ions were implanted into all the openings using the silicon dioxide film 4 as a mask. In order to activate the implanted impurities, a silicon nitride film 7 of 2,000 layers was grown in a vapor phase as shown in FIG.

As described above, according to this embodiment, by forming the silicon dioxide film as an ion implantation mask into a two-layer structure consisting of a heat-treated lower layer and an unheated upper layer, the etching cross section with a gentle slope can be exploded. The coverage of the film can be improved. Therefore, decomposition of the gallium arsenide substrate during heat treatment can be prevented.

In the first embodiment, the method for producing the silicon dioxide film was the atmospheric pressure chemical vapor deposition method, but the method for producing the silicon dioxide film is not limited to the atmospheric pressure chemical vapor deposition method. Any material may be used as long as it has the function of forming a film.

For example, plasma chemical vapor deposition can be used.

Further, in the second embodiment, the semiconductor substrate is made of gallium arsenide, but it goes without saying that the semiconductor substrate may be made of indium arsenide.

Effects of the Invention As described above, the present invention includes a step of forming a first silicon dioxide film by a chemical vapor deposition method, a heat treatment step of a first silicon dioxide film, and a step of forming a wiring metal or an insulating film to be formed into the first silicon dioxide film. The coating properties can be improved, and the practical effects thereof are great.

[Brief explanation of drawings]

1(&) to (dl are process cross-sectional views showing the conventional method for manufacturing a semiconductor device, and FIG.
A process cross-sectional view of a method for manufacturing a semiconductor device in an example of
FIG. 3 is a characteristic diagram showing the relationship between the etching rate of the silicon dioxide film and the heat treatment temperature, and FIG. be. 1...Silicon substrate, 2...Unheated silicon dioxide film, 3...--Photoresist,
4...Heat-treated silicon dioxide film, 6...
. . . Aluminum wiring layer, 6 . . . Gallium arsenide substrate, 7 . . . Silicon nitride film. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 1N2 Figure 3 Figure 1 Cram school!逼A(・C2 し

Claims (1)

[Claims] forming a first silicon dioxide film on a semiconductor substrate by chemical vapor deposition; heat treating the first silicon dioxide film; and forming the first silicon dioxide film on the first silicon dioxide film. forming a second silicon dioxide film by the same method as described above; simultaneously opening holes in the first and second silicon dioxide films; and removing the second silicon dioxide film. A method for manufacturing a semiconductor device, characterized by: