JPH02105517A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enable an improved and a large-area single crystal silicon(SOI) layer to be formed on an insulation layer by using the selective epitaxial growth method and the solid phase epitaxial growth method together. CONSTITUTION:A silicon oxide film 2 is formed on a silicon substrate 1, an opening part is provided, silicon selective epitaxial growth of silicon is made, and a selective epitaxial silicon film 3 of the same thickness as the film thickness of the silicon oxide film 2 is allowed to grow. Then, by using an inactive gas as a carrier gas, a amorphous silicon film 4 is allowed to grow, annealing is performed for 2 hours within an atmospheric pressure nitrogen environment, and the fixed epitaxial reaction of the amorphous silicon film 4 is generated, using the selective epitaxial silicon film 3 as a seed crystal, to form a single- crystal silicon layer 5. Thus, since the selective epitaxial growth and fixed epitaxial growth of silicon are adopted to form a large-area and improved SOI layer 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of forming a single crystal silicon layer on an insulating film.

[Conventional technology]

Conventionally, the technology for forming a single crystal silicon layer on an insulating film is
S OI (5ilicon On In5ulato
r) technology, and two methods are widely used: silicon selective epitaxial growth method and solid phase epitaxial growth method.

The silicon selective epitaxial growth method is described in the Journal of Crystal Growth.
stal Growth), Volume 63, 1983, 4
It was published on pages 93-526. First, this S
OI technology will be explained.

FIG. 2 is a cross-sectional view of a semiconductor wafer for explaining a method of forming a single crystal silicon layer by a conventional selective epitaxial growth method.

A silicon oxide film 2 having a thickness of 0.5 μm is formed on a single crystal silicon substrate 1, and this silicon oxide film 2 is selectively etched to provide an opening through which the surface of the silicon substrate is exposed. Next, selective epitaxial growth of silicon is performed.

For this, generally 5i82C! 22 or S
i Using H4 and H2, HCl. After the film thickness of the selective epitaxial silicon film 3 reaches the same film thickness as the silicon oxide film 2, lateral epitaxial growth (Epitaxia) of silicon is further performed laterally on the silicon oxide film 2.
1 Lateral Overgrowth) to form a single crystal silicon layer 5.

Next, a method for forming a single crystal silicon layer using solid phase epitaxial growth will be described.

FIG. 3 is a cross-sectional view of a semiconductor wafer for explaining a method of forming a single crystal silicon layer by a conventional solid phase epitaxial growth method.

A silicon oxide film 2 having a thickness of 0.2 to 0.5 μm is formed on a single crystal silicon substrate 1. Next, an opening is formed in this silicon oxide film 2 to expose the surface of the silicon substrate. Two methods are used to form the opening: selective oxidation and selective etching. After removing the natural oxide film formed in the six-opening groove with hydrofluoric acid, whichever method is used, the silicon substrate is immediately placed in an amorphous silicon film growth apparatus. Examples of the amorphous silicon film growth apparatus include a chemical vapor deposition apparatus, a sputter thin film apparatus, and an electron beam heating evaporation apparatus, and any of them may be used. Using these amorphous silicon film growth apparatuses, an amorphous silicon film 4 is grown on the surface of a silicon substrate to a thickness of approximately 0.5 to 2.0 μm.

Then 550°C to 6°C in dry nitrogen or argon atmospheric pressure.
Annealing is performed at a temperature of 50° C. for about 5 hours or more to perform solid phase epitaxial growth to convert the amorphous silicon film 4 into a single crystal silicon layer 5.

It is known that the monocrystalline silicon layer 5 formed in this way may locally contain polycrystalline silicon.
Physics Letters (Appli-ed Phys
ics Letters) Volume 43, No. 11, 198
3, pp. 1028-1030, and Japanese Journal of Applied Physics (Japan
ese Journal of Applied Ph.
ysics), Volume 23, No. 10, 1984, 129
It is described on pages 4-1299.

[Problem to be solved by the invention]

The conventional SOI layer forming technology described above has the following drawbacks.

First, in the SOI layer forming technology using the selective epitaxial growth method, while growing a single-crystal selective epitaxial silicon film 3 in the opening, when the film thickness becomes equal to or more than the same thickness as the silicon oxide film, the selective epitaxial silicon film 3 The growth is performed not only vertically but also horizontally on the silicon oxide film. At this time, the ratio of the growth rate in the vertical direction and the horizontal direction is 1
:1 or more is not stable, and in order to form a long selective epitaxial silicon film in the horizontal direction on a silicon oxide film, it is necessary to grow a selective epitaxial silicon film very thick in the vertical direction, or The gap between the openings was narrowed. In addition, the silicon films that have grown laterally from each opening collide with each other 6
However, it had drawbacks such as the formation of dislocations and voids.

On the other hand, in the SOI layer forming technology using the solid phase epitaxial growth method, the crystallinity of the epitaxial silicon film largely depends on the shape and plane orientation of the seed crystal and the flatness of the silicon oxide film and the seed crystal. With current opening formation technology, when the LOCO3 method is used, the silicon oxide film rises toward the opening side, called a bird's beak or bird's head, at the boundary between the insulating silicon oxide film and the seed crystal, and the silicon oxide film The crystal itself bulges out, and the flatness between the seed crystal and the silicon oxide film is poor, making it easy for dislocations and facets to occur during solid phase epitaxial growth of silicon. In addition, with respect to seed crystals formed in tapered openings in silicon oxide films using etching technology, facets may occur depending on the plane orientation of the seed crystals and the taper angle of the silicon oxide film, as described above. However, it has drawbacks such as forming a polycrystalline silicon film and causing dislocations.

[Means to solve the problem]

A method for manufacturing a semiconductor device according to the present invention includes a step of forming an insulating film on a single-crystal silicon substrate, a step of selectively etching the insulating film to form an opening that exposes the surface of the silicon substrate, and selection of silicon. a step of depositing a single crystal silicon film in the opening using an epitaxial growth method until it has the same thickness as the insulating film; and a step of depositing an amorphous silicon film on the entire surface including the insulating film and the single crystal silicon film. Then, the silicon substrate was heated to 500°C to 1200°C.
.degree. C. to perform solid phase epitaxial growth using the single crystal silicon film deposited in the opening as a seed crystal to convert the amorphous silicon film into a single crystal silicon layer.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIGS. 1(a) to 1(c) are cross-sectional views of a semiconductor wafer shown in the order of steps for explaining an embodiment of the present invention.

First, as shown in FIG. 1(a), a silicon oxide film 2 is formed on a silicon substrate 1, and a reactive ion etching method is applied to form a portion that will become a seed crystal necessary for epitaxial growth of silicon. Then, the silicon oxide film is selectively etched until the surface of the silicon substrate 1 is exposed, thereby forming an opening in the silicon oxide film 2. Next, a thermal oxide film several tens of nanometers thick is formed on the silicon surface of the opening by thermal oxidation, and then this thermal oxide film is removed with hydrofluoric acid. Immediately after removal, the silicon substrate 1 is placed into an epitaxial growth apparatus, and 5iH2Cρ2. Selective epitaxial growth of silicon is performed at a growth temperature of 900 to 1050° C. using H2 and HCρ, and a selective epitaxial silicon film 3 is grown to the same thickness as the silicon oxide film 2. The raw material gas contains SiH4 and Si2 instead of 5iH2CJ22.
A source gas capable of selective epitaxial growth of silicon, such as H6SiH2F2, may be used.

Next, as shown in FIG. 14(b), in the same apparatus as that in which the silicon selective epitaxial growth was performed, the temperature of the furnace was lowered to 580°C or less, and the source gases were SiH4 or Si2H6 and H2 or N2 or An amorphous silicon film 4 is grown using a similar inert gas as a carrier gas.

Next, as shown in Figure 1(c), after 48 hours of annealing in a nitrogen atmosphere at a furnace temperature of 600°C and atmospheric pressure, the furnace temperature was increased to 1150°C and atmospheric pressure. Annealing is performed for 2 hours in a nitrogen atmosphere to cause a fixed epitaxial reaction in the amorphous silicon film 4 using the selective epitaxial silicon film 3 as a seed crystal, thereby forming a single crystal silicon layer 5.

〔Effect of the invention〕

As explained above, the present invention employs a method that uses a combination of selective epitaxial growth and fixed epitaxial growth of silicon, and therefore has the effect of forming a high-quality SOI layer over a large area.

[Brief explanation of drawings]

FIGS. 1(a) to (C) are cross-sectional views of a semiconductor wafer shown in the order of steps to explain an embodiment of the present invention, and FIG. FIG. 3 is a cross-sectional view of a semiconductor wafer for explaining a method of forming a single crystal silicon layer by a conventional solid-phase epitaxial growth method. 1... Silicon substrate, 2... Silicon oxide film, 3.
... Selected epitaxial silicon film, 4... Amorphous silicon film, 5... Single crystal silicon layer, 6... Collision surface.

Claims (1)

[Claims] a step of forming an insulating film on a single-crystal silicon substrate; a step of selectively etching the insulating film to form an opening that exposes the surface of the silicon substrate; a step of depositing a single crystal silicon film in the opening until the film thickness is reached; a step of depositing an amorphous silicon film on the entire surface including the insulating film and the single crystal silicon film;
and converting the amorphous silicon film into a single crystal silicon layer by performing solid phase epitaxial growth using the single crystal silicon film deposited in the opening as a seed crystal by heat treatment at a temperature of 00°C to 1200°C. A method for manufacturing a semiconductor device, characterized by: