JPS6119118A - Manufacture of semiconductor substrate - Google Patents

Abstract

PURPOSE:To prevent generation of crystal defects on an epitaxially-grown Si layer and to enable to manufacture a flat semiconductor substrate by a method wherein an Si nitride film and then a polycrystalline or amorphous Si film are formed on the side wall of an insulating film before an epitaxial growing method is performed. CONSTITUTION:An SiO2 insulating film pattern 12 having a vertical cross-section is formed on a P type single crystal Si substrate 11, and then an Si nitride film 13 is deposited thereon. Then, after a film 13 is formed on the side wall only of an insulating film by performing a reactive ion etching method, amorphous Si 14 is deposited. Subsequently, an etching is performed on the Si 14 located on the insulating film and the substrate 11, and then Si 16 is selectively overetched. Then, Si 16 is selectively epitaxially grown on the surface only of the substrate 11. According to the above-mentioned method of manufacture, no crystal defects are generated on the epitaxially grown layer 16, and a flat semiconductor substrate can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method of manufacturing a semiconductor substrate in which a silicon epitaxial layer is selectively grown on a single crystal silicon layer having an insulating film pattern formed on its surface.

(Prior Art and its Problems) Recently, as a method for isolating active elements in semiconductor devices, a new technique that can form fine and deep element isolation regions is required in place of the selective oxidation method.

For example, as a method for forming fine and deep element isolation regions, Endo describes
In the paper published on pages 39 to 45 of 2 entitled "Element Isolation by Selective Epitaxial Growth", as shown in Figure 1(a)K, a silicon single crystal substrate 1
A silicon oxide film pattern 2 that will serve as an element isolation region is formed on the insulating film pattern 2 in advance, and then a silicon nitride film or a polycrystalline silicon thin film 3 is formed only on the side walls of the insulating film, and then exposed without being deposited on the insulating film pattern 2. When the silicon epitaxial layer 4 is grown only in the silicon substrate region, if the sidewall of the insulating film is a silicon nitride film, a facet 5 is formed in contact with the 8102 pattern 2 as shown in FIG. 1(b). If the substrate is uneven and polycrystalline silicon is formed on the sidewall of the insulating film, the pattern shown in Figure 1 (
It has been shown that a flat substrate can be obtained as shown in C).

However, when a transistor (for example, MOS) is formed on a semiconductor substrate having such a structure, the epitaxially grown silicon layer becomes an excellent single crystal without crystal defects when a silicon nitride film is used on the sidewall of the insulating film pattern. The step caused by the facet 5 formed in contact with the insulating film pattern becomes an obstacle when forming a gate electrode, for example. Furthermore, if polycrystalline or amorphous silicon is used for the sidewalls of the insulating film, a flat substrate can be obtained, but the epitaxially grown silicon layer 4 may have crystal defects near the sidewalls of the insulating film or deformation of the SiO□ pattern. As a result, problems such as the occurrence of leakage current in the tp'' junction and a decrease in dielectric strength voltage occurred, resulting in a decrease in manufacturing yield.

(Object of the Invention) An object of the present invention is to eliminate such conventional drawbacks and provide a method for manufacturing a flat semiconductor substrate in which no crystal defects occur in an epitaxially grown silicon layer.

(Structure of the Invention) The present invention includes forming an insulating film on a substrate having at least a silicon single crystal layer on the surface, first providing an opening in a desired portion of the insulating film, and then selecting only the opening. Provided is a method for manufacturing a semiconductor substrate in which a silicon film is grown epitaxially, the method comprising forming a silicon nitride film followed by a polycrystalline or amorphous silicon thin film on the sidewall of an insulating film before epitaxial growth. It is something.

(Detailed Description of Configuration) The present invention solves the problems of the prior art by adopting the above-described configuration. The epitaxially grown silicon layer and SiO2 are formed by forming a silicon nitride film layer on the side walls of the insulating film.
The interface characteristics with the pattern are improved, and an epitaxially grown silicon layer without crystal defects can be obtained. Further, by further providing a polycrystalline or amorphous silicon layer on the silicon nitride film, a flat semiconductor substrate can be obtained.

(Example) Examples of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a schematic diagram sequentially showing the cross section of the substrate in 1 main manufacturing process in order to explain the present invention in detail.・After forming a silicon oxide film with a thickness of 2 μm on the 8 i 02 insulating film (turn 12) with a vertical cross section that will become the element isolation region by using ordinary photolithography and reactive ion etching, Then, a silicon nitride film 13 is formed to a thickness of 100 mm by low pressure CVD method.
0^ When deposited, a substrate having the cross-sectional shape shown in FIG. 2(a) is obtained.

Next, the silicon nitride film on the insulating film and the silicon substrate is etched using a reactive ion etching method to form a silicon nitride film layer only on the side walls of the insulating film.
By depositing shear amorphous silico-cutting 4 to a thickness of 700^ by the D method, a substrate having the cross-sectional shape shown in FIG. When the amorphous silicon and the amorphous silicon on the silicon substrate are etched, and then the substrate silicon surface 15 is over-etched by about 1000λ, the pattern shown in FIG. 2 (C1) is obtained.

Next, add MC to the gas system consisting of 31H2CJ2 and H2.
Approximately 1% IVO was added to selectively epitaxially grow silicon only on the surface of the silicon substrate at a temperature of 950°C, and when the thickness of the deposited silicon 16 was 2 μm, as shown in Fig. 2 (
Obtain the structure of b).

Next, a gate oxide film 17 with a thickness of 200K is formed in an oxygen atmosphere at 950 DEG C., and boron is doubly implanted by ion implantation at an implantation amount of 1.times.10@12 C at an acceleration energy of 30 keV and at a dose of 2.times.10@12 cm@-2 at an acceleration energy of 100 keV.

Next, a shibori silicon film was formed to a thickness of 500 mm using the low pressure CVD method.
0^ is deposited, a Sigurt electrode ridge 18 is formed by photolithography and dry etching, and then 510 c+n ions are implanted with arsenic at an acceleration energy of 150 keV using a self-line, a source/drain layer 19 is formed, and a polysilicon gate is formed. When phosphorus is diffused into the electrode 18, Fig. 2(e)
- Next, a 1 μm aluminum film is deposited by electron beam evaporation.
The wiring 21 is formed by photolithography and dry etching. Next, a /custivation film 22 is deposited and a contact is made, resulting in an N layer as shown in FIG. 2(f).
Channel MO8FE'l'' is obtained.

(Effects of the Invention) The n-channel MOS transistor obtained from this example has superior gate breakdown voltage and reduced p-n junction leakage current compared to those obtained from the conventional method.

Manufacturing yield improved.

[Brief explanation of the drawing]

Figure 1 (al) is a cross-sectional view schematically showing the structure of the substrate before selective epitaxial growth is performed using the conventional method. FIG. 1(C) is a cross-sectional view schematically showing the substrate structure after epitaxial growth. FIG. 2 is a schematic cross-sectional view. FIGS. 2(a) to 2(f) are schematic cross-sectional views sequentially showing the manufacturing process of an n-channel MO8FET in an example of the present invention. In the figures: 1. 11...(100) silicon single crystal substrate,
2゜12-...5i02 insulation film pattern, 3...
・Silicon nitride film or polycrystalline silicon film, 4.16
...Epitaxially grown silicon layer, 5...Facet, 13...Silicon nitride film, 14...
・Amorphous silicon JIIE, 15...-Silicon substrate surface with over-elatin, 17...Gate oxide film, line aluminum g, 22...Passivation film Fig. 1 (C)

Claims (1)

[Claims] Manufacturing a semiconductor substrate by forming an insulating film on a substrate having a silicon single crystal on at least the surface, then providing an opening in a desired portion of the insulating film, and then epitaxially growing a silicon film selectively only in the opening. In the method,
1. A method of manufacturing a semiconductor substrate, which comprises forming a silicon nitride film followed by a polycrystalline or amorphous silicon thin film on the sidewall of an insulating film before epitaxial growth.