JPS6046046A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To simplify the steps by growing extremely thinly silicon nitride to become oxidation resistant mask, and altering all to silicon oxide at the time of forming a field oxidized film, thereby eliminating the necessity of removing the nitride. CONSTITUTION:A silicon oxidized film 2 is formed on a semiconductor substrate 1, and silicon nitride 3 to become an oxidation resistant mask is so thinly formed as to be oxidized and erased at the time of forming a field oxidized film. Silicon nitride 5 is etched, a channel stopper region 5 is formed by an ion implanting method, a photoresist film 4 is removed, an oxidation is achieved until the nitride 3 is erased, a field oxidized film 6 formed on the region 5 is composed of a silicon oxidized film 7 composed of the oxide 2 and silicon oxide converted from the nitride 3 on adjacent active regions.

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing a semiconductor device.

When forming a field oxide film to be buried in a semiconductor substrate using a conventional semiconductor device manufacturing method, a first insulating film is first formed on the semiconductor substrate, and then a silicon nitride tl-2 film is formed as an oxidation-resistant mask. The field oxide film was formed to a thickness of about 1000 Å, patterned as desired, impurities to become a channel stopper were formed by ion implantation, etc., and a heat treatment was performed using the silicon nitride as a mask to form the field oxide film.

According to such conventional methods, when forming a field oxide film, the surface of silicon nitride changes to silicon oxide,
When removing silicon nitride.

First, the silicon oxide on the surface of the silicon nitride used as an oxidation-resistant mask was removed, and then the silicon nitride used as an oxidation-resistant mask was removed using the method described above.
Must be completely removed.

Also, when forming the silicon nitride that becomes oxidation-resistant → sulfur, this nitride should not be too thick.

There are various effects on the conductive substrate due to the difference in thermal expansion coefficient from silicon oxide. In addition, the silicon nitride that remains unoxidized when forming the field oxide is not essential to the semiconductor device itself, so this silicon nitride must be removed by some method, and the silicon nitride must be removed by some method. Therefore, an unnecessary manufacturing process is required, and it cannot be said that the semiconductor device is not affected by the unnecessary manufacturing process.

The present invention aims to eliminate such conventional disadvantages.

To correct the above-mentioned disadvantages, silicon nitride, which serves as an oxidation-resistant mask, must be grown as thinly as possible.

By converting all silicon nitride into silicon oxide when forming a field oxide film, the influence on the semiconductor substrate can be reduced, and there is no need to remove the remaining silicon nitride without being oxidized.

Also, growing silicon nitride thinly.

The fact that there is no need to worry about removing silicon nitride also leads to a reduction in process time, and the effect is tremendous.1 The purpose of the present invention is to cause less damage and to eliminate unnecessary steps. And so. A method of manufacturing an MO8 semiconductor device having buried field oxide is provided.

The present invention will be described in detail below using the drawings.

First, as shown in FIG.
A silicon oxide film covering the insulating film 2 is formed by a thermal oxidation method, and a silicon nitride 3 serving as an oxidation-resistant mask is formed on it so thinly and uniformly that it will not be oxidized during the formation of the field oxide film (100). Form. Next, as shown in FIG. 2, a desired pattern is created using 7-otoresist 4.

Irconium nitride 5, which serves as an oxidation-resistant mask, is etched using an existing method. After that, a channel stopper region 5 for preventing parasitic effects is formed using photoresist 4°, silicon nitride 3,
A layer is formed by ion implantation using silicon oxide 2 as a mask. After that, the photoresist film 4 is removed and cleaning is performed.

Field oxide film 6 is oxidized until silicon nitride 3 in FIG. 2 is removed. FIG. 3 shows this state. That is, a field oxide film is formed on the channel stock/<- region, and a field oxide film is formed on the active region adjacent to the field oxide film.
2, 7, 3. 2.3, a silicon oxide film 7 composed of the deposited silicon oxide is formed. If you use this method.

There is no need to remove the silicon nitride that remains unoxidized after the field oxide film is formed, and the number of steps required for this purpose can also be omitted. Furthermore, since the silicon nitride is formed thinly, the adverse effects on the semiconductor substrate due to differences in thermal expansion coefficients can be reduced.

[Brief explanation of drawings]

1 to 3 show a method of manufacturing a semiconductor device according to this embodiment. In the same figure, 1... semiconductor substrate, 2...
...Silicon oxide, which is the first insulating film, 3...
・・Silicon oxide that serves as an oxidation-resistant mask, 4・・・・
・Photoresist, 5...Channel stopper region, 7...Silicon oxide film. Figure 1

Claims (1)

[Claims] After forming the first silicon oxide on the semiconductor substrate, a thin layer of silicon nitride is formed as an oxidation-resistant mask, and then all of the silicon nitride is removed by heat treatment when forming a field oxide film to be buried in the semiconductor substrate. A method for manufacturing a semiconductor device, comprising a step of converting silicon oxide into a second silicon oxide.