JPH01161851A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To make a bird's beaks and defects in a LOCOS edge part hardly develop by a method wherein, after a side wall consisting of semiconductor is formed on the side wall of a three-layer laminated film formed by laminating selectively a semiconductor oxide film, a semiconductor film and an oxidation- resistant film on a semiconductor substrate, the side wall and the semiconductor substrate are selectively oxidized using the oxidation-resistant film as a mask to form an element isolation insulating film. CONSTITUTION:A semiconductor oxide film 2, a semiconductor film 10 and an oxidation-resistant film 3 are formed on a semiconductor substrate 1 and this laminated film is selectively etched to form an aperture 6, which is used as an interelement isolation region. At this time, the substrate 1 is exposed by slightly overetching. Then, polySi is deposited to form a semiconductor layer 7 and the layer 7 is selectively etched to form a side wall 4 consisting of semiconductor on the side wall of the three-layer laminated film. Then, a channel stop region is formed by ion implantation and the side wall 4 and the substrate 1 are selectively oxidized using the film 3 as a mask. Thereby, an element isolation insulating film 5 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a semiconductor device. The present invention
For example, it can be applied to a manufacturing method for forming an isolation region between elements of a semiconductor LSI, and in particular, when forming an isolation insulating film (specifically, during thermal oxidation), defects occur at the so-called loco edge portion at the end of the isolation region. The present invention relates to a method for manufacturing a semiconductor device that can prevent such problems.

[Summary of the invention]

In the present invention, after forming a sidewall made of a semiconductor on the side wall of a three-layer laminated film formed by selectively laminating a semi-quadramid oxide film, a semiconductor film, and an oxidation-resistant film on a semiconductor substrate, By selectively oxidizing the film as a mask to form an element isolation insulating film, it is possible to form a thin semiconductor oxide film, thereby creating a semiconductor device with almost no bird's beak (and almost no defects at the locus edge). can be obtained through a simple process.

[Background of the invention]

In the field of semiconductor devices, element miniaturization, such as L
With the miniaturization of SI elements, there is a need for an element isolation method that is less likely to cause -layer bird's beak.

As a means of element isolation method, Japanese Patent Application Laid-Open No. 61-74350
This paper describes a technique for forming an element isolation insulating film without forming sidewalls. Further, as a promising means, as shown in FIG. 3 Ta, a side wall 4 made of a semiconductor (for example, poly-Si) is formed on the side wall of the oxidation-resistant film 3 made of, for example, 5iJ4 and the semiconductor oxide film 2 made of, for example, SiO□. There are some methods that try to suppress the occurrence of bird's beaks. Specifically, for example, S shown in FIG. 3(b)
When forming the element isolation insulating film 5 made of iO□ (during thermal oxidation), the sidewall 4 is
This prevents oxygen from entering the semiconductor oxide film 2 until it is completely oxidized, thereby suppressing the occurrence of bird's beaks. (
In addition, in FIG. 3 Tag, (b), 1 is, for example, S
A semiconductor substrate consisting of i. ) The prior art will be explained in more detail below.

FIGS. 4(a) to 4(e) are diagrams for explaining a conventional method of manufacturing a semiconductor device.

In these figures, the same reference numerals as in FIGS. 3(a) and 3(b) indicate the same or corresponding parts, 6 is an opening, and 7 is a semiconductor layer made of poly-Si, for example.

Next, the manufacturing method will be explained.

First, as shown in FIG. 4(a), after forming a semiconductor oxide film 2 with a thickness of, for example, 300 on a semiconductor substrate 1 by thermal oxidation or the like, a Si
, N, are deposited to form an oxidation-resistant film 3 having a thickness of, for example, 1000 nm.

Next, as shown in FIG. 4(b), the oxidation-resistant film 3 and the semiconductor oxide film 2 are selectively etched using, for example, RrE to form openings 6 that will serve as isolation regions. At this time, the semiconductor substrate 1 is reliably exposed by slightly over-etching.

Next, as shown in FIG. 4 (C1), a semiconductor layer 7 is formed by depositing poly-Si over the entire surface by, for example, the CVD method.

Next, as shown in FIG. 4(d), the semiconductor layer 7 is selectively etched using, for example, RIB to form sidewalls 4 on the side walls of the oxidation-resistant film 3 and the semiconductor oxide film 2. Then, as shown in FIG.

Next, a channel stop region (not shown) is formed by ion implantation.

Then, as shown in FIG. 4(e), by selectively oxidizing the sidewall 4 and the semiconductor substrate 1 using the oxidation-resistant film 3 as a mask, an element isolation insulating film 5 is formed.

In the conventional manufacturing method described above, the sidewall 4 is formed by etching the semiconductor layer 7, but according to the findings of the present invention, the sidewall 4 is formed by selectively oxidizing the semiconductor layer 7. can also be considered.

Specifically, first, the semiconductor layer 7 shown in FIG. Then, an oxide film 8 of, for example, 5 in 2 is formed (FIG. 5(b)). At this time, the sidewall 4 is formed as an unoxidized portion of the semiconductor layer 7. Next, Figure 5 (C
), the oxide film 8 is removed by, for example, wet etching.

Thereafter, in the same manner as in the conventional method described in FIG. (not shown) is obtained.

[Problem that the invention seeks to solve]

However, in the conventional manufacturing method described above, when forming the element isolation insulating film 5 as shown in FIG. This progresses from the loco edge portion 9 to the dotted line B portion.) This has been a problem in that it is likely to occur. This is because, especially when the sidewall 4 is oxidized, stress is applied in the direction A in which the oxidation-resistant film 3 is turned over due to the expansion (expansion direction, B) of the oxidized portion, and this stress is perpendicular to the semiconductor substrate 1. It is thought that this acts as a tensile stress in the direction and causes a defect (dotted line B) to occur in the loco edge portion 9.

Furthermore, as a means to solve the above-mentioned problems, it is possible to form the semiconductor oxide film 2 thickly to relieve the stress (particularly the stress acting on the semiconductor oxide film 2) and to suppress the occurrence of defects in the locus edge portion 9. If the semiconductor oxide film 2 is made thicker, there is a problem in that bird's beaks are more likely to occur.

[Purpose of the invention]

The present invention has been made to solve such problems, and can suppress the occurrence of defects in the loco edge portion.
Another object of the present invention is to provide a method for manufacturing a semiconductor device that can form a thin semiconductor oxide film and suppress the occurrence of bird's beak.

[Means for solving problems]

A method for manufacturing a semiconductor device according to the present invention includes a step of selectively laminating a semiconductor oxide film, a semiconductor film, and an oxidation-resistant film on a semiconductor substrate to form a 3N laminated film, and a side wall of the three-layer laminated film. The method includes a step of forming a sidewall made of a semiconductor, and a step of selectively oxidizing using the oxidation-resistant film as a mask to form an element isolation insulating film.

The configuration of the present invention will be described below using an embodiment of the present invention which will be described in detail later.

That is, in the present invention, as illustrated in FIGS. 1A to 1E, a semiconductor oxide film 2, a semiconductor film 10, and an oxidation-resistant film 3 are selectively laminated on a semiconductor substrate l to form a three-layer structure. Laminated film (here, the three-layered laminated film is semiconductor oxide film 2, semiconductor JI
Figure 1(a)
), as shown in FIG. 1(d), after forming a side wall 4 made of a semiconductor on the side wall of the three-layer stacked film, an oxidation-resistant film 3 is formed as shown in FIG. 1(e). The element isolation insulating film 5 is formed by selectively oxidizing using a mask.

In the present invention, the step of forming a sidewall made of a semiconductor on the sidewall of the three-layer laminated film is, for example, selectively etching the semiconductor layer (for example, poly-Si) formed covering the laminated film to form the sidewall. The present invention includes an embodiment in which the process is a process for forming a sidewall, and an embodiment in which the process is a process in which a sidewall is formed by selectively oxidizing a semiconductor layer formed covering a laminated film.

[Effect]

In the present invention, a semiconductor film is formed between the oxidation-resistant film and the semiconductor oxide film, and as a result, when forming the element isolation insulating film, the stress applied in the direction in which the oxidation-resistant film turns over is alleviated, and the loco-sweep portion Almost no defects will occur.

Furthermore, since the semiconductor film can be formed to a suitably predetermined thickness so as not to cause defects in the locus edge portion, the semiconductor oxide film can be formed thinly, and bird's beaks are almost never generated.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

It should be noted that, as a matter of course, the present invention is not limited to the examples described below.

FIGS. 1(a) to 1(e) are diagrams for explaining one embodiment of the method for manufacturing a semiconductor device of the present invention.

In these figures, the same reference numerals as in FIGS. 4 Ta) to (e) indicate the same or corresponding parts, and 10 is a semiconductor film made of poly-Si, for example.

Next, the manufacturing process will be explained.

First, as shown in FIG. 1(a), after selectively forming a semiconductor oxide film 2 with a thickness of 50 mm on a semiconductor substrate 1 by, for example, a thermal oxidation method, a polyamide film is formed on the semiconductor oxide film 2 by, for example, a CVD method. Sis 5iJa is sequentially deposited to selectively form a semiconductor film 10 with a thickness of 300 densities and an oxidation-resistant film 3 with a thickness of 1000 densities. This corresponds to the step of forming the semiconductor oxide film, semiconductor film, and oxidation-resistant film of the present invention.

Next, as shown in FIG. 1(b), the semiconductor oxide film 2, the semiconductor film 10, and the oxidation-resistant film 3 are selectively etched to form openings 6 that will serve as isolation regions between elements. At this time, the semiconductor substrate 1 is exposed by slightly overetching.

Next, as shown in FIG. 1C, poly-Si is deposited over the entire surface by, for example, the CVD method to form a semiconductor N7 with a thickness of 1500 nm.

Next, as shown in FIG. 1 (dl), the semiconductor layer 7 is selectively etched by, for example, RIE to form a sidewall of the three-layer stacked film (oxidation-resistant film 3, semiconductor film 10, semiconductor oxide film 2). A sidewall 4 made of a semiconductor is formed. This corresponds to the step of forming a sidewall made of a semiconductor according to the present invention.

Next, a channel stop region (not shown) is formed by ion implantation.

Then, as shown in FIG. 1E, by selectively oxidizing the sidewall 4 and the semiconductor substrate 1 using the oxidation-resistant film 3 as a mask, an element isolation insulating film 5 is formed. This forms the element isolation insulating film 5 of the present invention.

That is, in the above embodiment, the semiconductor film 10 is formed between the oxidation-resistant film 3 and the semiconductor oxide film 2, so that when forming the element isolation insulating film 5, the oxidation-resistant film 3 is turned over in the direction A (
The stress (especially the stress that acts as a tensile stress in the vertical direction to the semiconductor substrate 1) applied to A) shown in FIG. This is because the semiconductor film 10, which has better elasticity than the semiconductor oxide film 2, is subjected to stress (A in FIG. 6) in the direction A (A shown in FIG.
This is thought to be due to the relaxation of tensile stress.

Further, the semiconductor film 10 is attached to the loco edge portion 9 shown in FIG.
Since the semiconductor oxide film 2 can be formed to a suitably predetermined thickness so as not to cause defects, the semiconductor oxide film 2 can be formed thinly, and bird's beaks hardly occur.

In the above embodiment, as shown in FIG. 1(d), the sidewall 4 is formed by selectively etching the semiconductor layer 7, but the present invention is not limited to this. (, the semiconductor layer 7 (semiconductor M
The process up to the formation of 7 is the same as that described in the manufacturing method of the above embodiment. ) may be selectively oxidized to form the sidewall 4 as shown in FIG. 2(b). In this case, in addition to the effects of the above embodiments, damage to each semiconductor layer (for example, the semiconductor substrate 1) is reduced, and the shape difference in the element isolation insulating film 5 is reduced, making planarization possible. be.

〔Effect of the invention〕

As described above, according to the present invention, a semiconductor oxide film can be formed thinly, bird's beaks hardly occur, and defects at the locus edge part hardly occur.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining one embodiment of the method for manufacturing a semiconductor device according to the present invention, and FIG. 2 is a diagram for explaining another embodiment of the method for manufacturing a semiconductor device according to the present invention. 3 is a diagram for explaining a conventional element isolation method, FIG. 4 is a diagram for explaining an example of a conventional method for manufacturing a semiconductor device, and FIG.
The figure is a diagram for explaining another example of the method for manufacturing a semiconductor device, and FIG. 6 is a diagram for explaining the problem to be solved by the present invention. DESCRIPTION OF SYMBOLS 1... Semiconductor base, 2... Semiconductor oxide film, 3... Oxidation resistant film, 4... Side wall made of semiconductor, 5... ...Element isolation insulating film, 10...Semiconductor film.

Claims (1)

[Claims] 1. A step of selectively laminating a semiconductor oxide film, a semiconductor film, and an oxidation-resistant film on a semiconductor substrate to form a three-layer laminated film, and a semiconductor on the sidewall of the three-layer laminated film. 1. A method of manufacturing a semiconductor device, comprising: forming a sidewall comprising: a step of selectively oxidizing using the oxidation-resistant film as a mask to form an element isolation insulating film.