JPS58132947A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To realize an excellent isolating structure, composed of an oxide film, with few crystal defects by a method wherein a crystal defects absorbing region in the vicinity of an inter-element oxide film isolating a semiconductor island region. CONSTITUTION:An Si nitride film 33 is formed surrounding a semiconductor island region 34 and a region 32 not included in said island region 34. The top and sides of the region 34 are covered with the film 33 with the intermediary of an Si oxide film 35 while the sides of the region 32 have no Si oxide film intermediary. Within the region 32, a number of crystal defects 37 are generated, under stress exerted by the film 35, wherein the region 32 absorbs the defects to be created otherwise in the region 34. The sides of the region 34 being covered with the film 33, an isolating oxide film 36 has virtually no lateral penetration, which results in a fine structure precise in dimensions of an isolating oxide film.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device in which crystal defects are less likely to occur in semiconductor island regions separated between elements.

The method of using an oxide film for element isolation allows the area of the semiconductor element to be smaller than pn junction isolation, is suitable for higher density, and is very advantageous for higher evolution and lower power consumption. A selective oxidation method is widely used as a method for forming an oxide film isolation structure, but crystal defects generated in semiconductor island regions due to selective oxidation have been a problem.

FIGS. 1A to 1C show cross-sectional views of conventional oxide film separation processes. First, as shown in the figure (-), an underlying silicon oxide film 2 is placed on a silicon substrate 1.
After forming the silicon nitride film 3, the resist 4 is partially opened leaving a portion where a semiconductor island region will be formed. Next, as shown in FIG. Φ), the silicon nitride film 3 is removed by plasma etching using the resist 4 as a mask, and the underlying silicon oxide film 2 is etched away using a hydrofluoric acid-based etching solution. Subsequently, the silicon substrate 1 is etched to a desired depth by anisotropic sputter etching.

Next, as shown in FIG. 4C, after removing the resist 4, selective oxidation is performed using the silicon nitride film 3 as a mask to form an isolation oxide film 6. Thereafter, the silicon oxide film on the silicon nitride film 3 grown during the formation of the isolation oxide film is removed, and the silicon nitride film 3 is further removed to complete the oxide film isolation structure.

In the conventional example described above, as shown in FIG. 1(C), crystal defects 7 are generated in the semiconductor island region 6 where an element is formed due to stress during selective oxidation, and the element formed in the semiconductor island region 6 is This causes a significant deterioration of the electrical characteristics of the It is very difficult to eliminate stress during selective oxidation, which is a factor in the generation of crystal defects, and the generation of crystal defects is unavoidable.

The present invention has been made in view of the above-mentioned drawbacks, and it is an object of the present invention to provide a method for manufacturing a semiconductor device having a good oxide film isolation structure with few crystal defects. The present invention provides a method for manufacturing a semiconductor having an oxide film isolation structure so as to prevent defects from occurring in a semiconductor island region, and the structure of the present invention will be explained in detail below using examples.

FIGS. 2A to 2C are process cross-sectional views showing a method of manufacturing a semiconductor device having an oxide film isolation structure according to an embodiment of the present invention. FIG. 5A shows a cross-sectional view before the isolation oxide film is formed by selective oxidation.

On the surface of the silicon substrate 11 that will become the semiconductor island region 14,
An underlying silicon oxide film 12 and a silicon nitride film 13 are formed, and openings 16 and 17 of desired depth are formed at locations where element isolation oxide films are to be formed. Only silicon nitride film 13 is formed on the surface of region 16 that does not become a semiconductor island.

FIG. 2B shows a structure in which selective oxidation is performed using the silicon nitride film 13 as a mask to form element isolation oxide films 18 and 19 in the openings 16 and 17, respectively.

Here, when performing selective oxidation using the silicon nitride film 13 as a mask, a method is used to insert the underlying silicon oxide film 12 under the silicon nitride film 13 in order to alleviate the stress applied to the silicon substrate by the silicon nitride film. However, no underlying silicon oxide film is inserted on the silicon substrate surface 16 that does not become a semiconductor island. Therefore, a large number of crystal defects 20 occur in the silicon substrate region 16.

On the other hand, since the underlying silicon oxide film is inserted on the silicon substrate surface 1 of the semiconductor island region 14, the stress applied to the silicon substrate is alleviated, and defects that should occur in the island region 14 are removed from the adjacent defect-prone region 16. The island region 14 can become a very good substrate with few crystal defects.

FIG. 2 shows a second embodiment of the present invention, in which a silicon nitride film is also formed on the side surface of the opening in the silicon substrate and selective oxidation is performed to form an isolation oxide film. As shown in FIG. 3A, a silicon nitride film 33 is formed on the side surfaces of the semiconductor island region 34 and the region 32 that will not become a semiconductor island.

A silicon oxide film 36 is formed on the upper and curved side surfaces of the semiconductor island region 34.
A silicon nitride film 33 is formed therebetween. on the other hand,
No silicon oxide film is inserted into the side surfaces of the region 32 that will not become a semiconductor island. The same figure [with]) shows silicon nitride film 3.
The structure after the isolation oxide film 36 is formed by the selective oxidation method using 6 as a mask is shown.

As described above, according to this embodiment, the silicon oxide film 3 is formed on the side surface.
In the region 32 which does not become a semiconductor island where 5 is not inserted, a large number of crystal defects 37 are generated due to the stress caused by the silicon nitride film 36, which has the effect of absorbing defects that should occur in the semiconductor island region 34. . Furthermore, since the silicon nitride film 33 is formed on the side surface of the island region 34, there is almost no lateral oxidation in the isolation oxide film 36, and a fine oxide film isolation structure with good dimensional accuracy can be formed.

As described above, according to the present invention, it is possible to improve the performance of large-scale integrated semiconductor devices, and therefore it is very effective in the semiconductor manufacturing process.

[Brief explanation of the drawing]

1(a) to 1(C) are process cross-sectional views showing a method of manufacturing a semiconductor device having a conventional oxide film isolation structure, and FIG. 2(a)
-(b) are process cross-sectional views showing a method for manufacturing a semiconductor device having an oxide film isolation structure according to an embodiment of the present invention, and FIG.
a) to middle) show process cross-sectional views showing other embodiments of the present invention. 14.34...Island area, 12, 35...
Silicon oxide film, 13.33...Silicon nitride oxide, 15°32...Defect absorption region. Name of agent: Patent attorney Toshio Nakao and one other person II
Figure 4 ((1) tbノ(C) 7 2nd cause ta) ” (b)

Claims (1)

[Claims] forming a first silicon nitride film via a silicon oxide film on the semiconductor island region where the device is to be formed, and forming a second silicon nitride film in a predetermined portion within the device isolation region; 1. A method of manufacturing the above-mentioned type by performing selective oxidation using the second silicon nitride film as a mask.