JPH0746683B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION [Outline] An insulating film is thermally generated on a single crystal semiconductor substrate, and a supporting substrate is bonded to the insulating film. Then, after the semiconductor substrate is removed by etching, a semiconductor film made of the same material as the semiconductor substrate is grown on the surface of the insulating film that was in contact with the semiconductor substrate. Then, the semiconductor film becomes a single crystal thin film with good crystal quality.

TECHNICAL FIELD The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for forming a single crystal semiconductor substrate of an SOI structure semiconductor device.

Recently, a semiconductor device having an SOI (Silicon On Insulator) structure has been attracting attention because a semiconductor device advantageous for high-speed operation, radiation resistance, and high-temperature operation can be manufactured. For example, if the layers are three-dimensionally (three-dimensionally) stacked and highly integrated, the effect of reducing the parasitic capacitance for the insulating substrate is synergized, and high-speed operation can be obtained.

However, it is important to form a semiconductor device with such an SOI structure on a substrate that has crystal quality as high as possible.
There is a demand for higher quality.

[Problems to be Solved by Conventional Techniques and Inventions] Now, SOS (Si
licon On Sapphire) substrate is known, it is the second
As shown in the cross-sectional view of the figure, this is a substrate in which silicon is epitaxially grown on a sapphire substrate 1 to form a single crystal silicon film 2. That is, since the sapphire substrate is a material having a high melting point, when heated to about 1200 ° C. and growing a silicon film thereon, a crystalline silicon film along the sapphire crystal is formed.

However, although the sapphire substrate is very expensive, and although sapphire and silicon have similar crystal structures, there are still crystallographic differences, and there is a mismatch of crystal lattices at the interface. The generated and formed silicon film 2 contains many crystal defects. Therefore, compared with the silicon substrate prepared by the conventional pulling method or the band refining method, the crystal quality is not good, so that the SOS substrate has not been widely used.

On the other hand, a recently proposed SOI substrate has a beam-annealed SOI substrate, and a method for forming the SOI substrate will be described with reference to FIGS. 3 (a) and 3 (b). First, as shown in FIG.
An O ₂ ) film 4 is formed, and a polycrystalline silicon film 5 is deposited thereon by a chemical vapor deposition (CVD) method. Also, at this time, S
A silicon nitride (Si ₃ N ₄ ) film may be formed instead of the iO ₂ film, and an amorphous silicon film may be grown instead of the polycrystalline silicon film.

Next, as shown in FIG. 3B, the polycrystalline silicon film 5 is heated and melted by scanning with, for example, a continuous argon laser (CW-Ar Laser) beam (this is beam annealing,
This example is laser annealing), and the polycrystalline silicon film is transformed into the single crystal silicon film 5.

However, it is difficult to completely single-crystallize the polycrystalline silicon film 5 in the SOI substrate formed by this method, and the crystal quality is not so good even if it is single-crystallized. Therefore, a semiconductor element is formed on the crystalline silicon film 5 which is unavoidably defective and of poor quality.

In addition, various fabrication methods have been attempted to improve the crystal quality of the crystalline silicon film 5 by improving the basic formation method shown in FIG.
A method is known in which a seed that becomes a nucleus is provided, and laterally epitaxial growth is performed from the seed. However, even if it is formed in this way, it is very difficult to remove defects in the vicinity of the interface with the insulating film, and as a result, a silicon thin film with excellent crystal quality has not yet been formed.

The present invention proposes a method for forming an SOI structure substrate that solves such problems and obtains a single crystal thin film with good crystal quality.

[Means for Solving Problems] The purpose is to adhere a support substrate onto an insulating film (eg, SiO ₂ film) formed on the surface of a semiconductor substrate (eg, silicon substrate), and then to attach the semiconductor substrate to the semiconductor substrate. A semiconductor including a step of growing a semiconductor film of the same material as the semiconductor substrate on the surface of the insulating film which is in contact with the semiconductor substrate after etching removal (for example, etching removal by photoexcitation etching method containing halogen gas) This is accomplished by the method of manufacturing the device.

[Operation] That is, according to the present invention, the insulating film is thermally generated on the single crystal semiconductor substrate, and the supporting substrate is bonded onto the insulating film. Next, after the semiconductor substrate is removed by etching, a semiconductor film made of the same material as the semiconductor substrate is laminated on the surface of the insulating film that was in contact with the semiconductor substrate. Then, the insulating film that was in contact with the semiconductor substrate has a surface that inherits the interface state that tends to be single-crystallized and has few crystal defects. Therefore, the single-crystal semiconductor film grown on it has excellent crystal quality. become.

[Examples] Hereinafter, examples will be described in detail with reference to the drawings.

FIGS. 1 (a) to 1 (d) show sectional views in order of forming steps of the forming method according to the present invention. First, as shown in FIG. 1 (a), in a high temperature oxidizing atmosphere of about 1000 to 1200 ° C. The silicon substrate 11 is heated with, and the film thickness of about 1 μm
The SiO ₂ film 12 is generated. SiO ₂ produced by this high temperature oxidation
The film 12 is a good quality film having good insulation and very few crystal defects at the interface. In this process, a method of forming a Si ₃ N ₄ film by heat treatment in a high temperature atmosphere of ammonia gas can be considered.

Next, as shown in FIG. 1B, another silicon substrate or a quartz substrate 13 (support substrate) on the SiO ₂ film 12 is bonded. In the bonding method, for example, phosphorus silicate glass (PSG) is thinly laminated on the SiO ₂ film 12 by the CVD method, and this is melted and bonded. Since this phosphorus silicate glass melts at a low temperature of about 900 ° C., it can be easily bonded. Also, Si
The O ₂ film 12 itself may be melted and adhered at a high temperature.

Then, as shown in FIG. 1C, the silicon substrate 11 is removed by etching. For the etching, a gas containing halogen, for example, chlorine gas is used as a reaction gas, and an etching method of irradiating the reaction portion with ultraviolet rays, a so-called photo-excited dry etching method is used. Further, the silicon substrate can also be removed by a wet etching method using a caustic potash solution. In short, silicon substrate and Si
It is removed by using an etching method having a large etching selection ratio with respect to the O ₂ film.

Then, as shown in FIG. 1 (d), a film thickness of 1 μm is formed on the SiO ₂ film at the interface with the silicon substrate exposed by etching.
A silicon film 14 is grown. At this time, the Si of the exposed interface
Since the O ₂ film surface inherits the bond of the crystal lattice bonded to the silicon substrate as it is, the silicon film 14 deposited thereon is in a state of being easily single-crystallized.

In this case, the growing silicon film 14 may be grown at a relatively low temperature and either polycrystalline silicon or amorphous silicon may be laminated and beam-annealed to single crystallize it. Instead of such vapor phase growth, a solid phase growth method may be used. In addition, the silicon film 14 at high temperature
, A single crystal silicon film grows, but any of these methods may be adopted.

The single crystal silicon film 14 thus formed has a small number of defects and crystal quality because the silicon film is grown on the surface of the SiO ₂ film 12 which has inherited the interface state with the silicon substrate to form a single crystal. A highly crystalline single crystal silicon film is formed.

Moreover, it goes without saying that if a semiconductor element is formed on such a single crystal silicon film 14, a high-quality element with a small parasitic capacitance is formed and the semiconductor device is of high quality and high reliability.

[Effects of the Invention] As is clear from the above description, according to the present invention, a high-quality substrate having an SOI structure can be obtained, and the quality and reliability of the semiconductor device formed thereon can be further improved.

[Brief description of drawings]

1 (a) to 1 (d) are cross-sectional views in order of steps of forming an SOI structure substrate according to the present invention, FIG. 2 is a cross-sectional view of a conventional SOS substrate, and FIGS. 3 (a) and 3 (b) are conventional cross-sectional views. FIG. 7 is a sectional view in order of the steps of forming the SOI substrate. In the figure, 1 is a sapphire substrate, 2 is a single crystal silicon film, 3 and 11 are silicon substrates, 4 and 12 are SiO ₂ films, 5 and 14 are polycrystalline silicon films (amorphous silicon films) or single crystal silicon films, 13
Indicates a silicon substrate or a quartz substrate (support substrate).

Claims (3)

[Claims] 1. A support substrate is adhered onto an insulating film formed on the surface of a semiconductor substrate, and then the semiconductor substrate is removed by etching, and then contacted with the semiconductor substrate to form the same film on the surface of the insulating film as the semiconductor substrate. A method of manufacturing a semiconductor device, comprising the step of growing a semiconductor film of a material. 2. The semiconductor substrate is a silicon substrate, and the insulating film is composed of a silicon oxide film formed by thermal oxidation or a silicon nitride film formed by thermal nitriding. A method of manufacturing a semiconductor device according to claim 1. 3. The method of manufacturing a semiconductor device according to claim 1, wherein the etching method for removing the semiconductor substrate by etching is a photoexcitation etching method in a gas containing halogen.