JPS5840820A - Formation of silicon single crystal film - Google Patents

Abstract

PURPOSE:To obtain uniform and high-quality single crystal films by a method wherein amorphous or polycrystalline Si films are firstly accumulated in insular shape on a substrate when Si single crystal films are formed on a single crystal insulating substrate and after providing a film of Au, Ag, Al, Pt or the like on the films, heating treatment is applied under inactive gas atmosphere or under vacuum. CONSTITUTION:A plurality of amorphous or polycrystalline films 2 are deposited in insular shape on a single crystal insulator substrate 1 of sapphire, spinel, silicon carbide or the like, and a metal film 3 of Au, Ag, Al, Pt or the like acting eutectic reaction with Si is covered on the whole surfaces including the substrate 1 and films 2. Next, heating treatment is applied under inactive gas atmosphere such as N2, HC or the like or under vacuum of 10<-3> Torr and the films 2 are changed to single crystal film 4. This permits single crystalization at low temperatures to decrease a defect reducing crystallization and high-quality single crystal films can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a silicon single crystal film on a single crystal insulating substrate.

5O8 (Silicon
on 5apphire) substrates are known.

Hereinafter, SO8 will be explained as an example. SO8 is a growth furnace containing a sapphire substrate heated to a desired temperature.
ll14) and other raw material gases for thermal decomposition.
A silicon single crystal film is formed on a sapphire substrate.

However, in this growth method, the growth temperature is 9.
A temperature range of 50°C to 1000°C is used, and due to the difference in lattice constant and coefficient of thermal expansion between the sapphire substrate and the silicon single crystal, many dislocations, planar defects, compressive strain, etc. are introduced into the resulting silicon film. It is known to put it away. These defects that reduce crystallinity are considered one of the problems in manufacturing MOS devices.

On the other hand, some attempts have been made to improve the crystallinity of the growth bales for several nights in order to improve these problems, but the purpose of the present invention is to improve the basic single-crystal film formation method. It is related to.

Therefore, in order to improve the above drawbacks, the present inventors have discovered a method of epitaxially growing a silicon single crystal film with few crystal defects on a single crystal insulator substrate.

The present invention utilizes the phenomenon that metal-silicon causes a eutectic reaction at a relatively low temperature, and a silicon single crystal is precipitated by this reaction.

Conventionally, an epitaxial growth method utilizing this metal-silicon eutectic reaction (J.E., Davey: App.
l.

Phya, Lett, 28.365 (1976)) was known, but in this case, the substrate used was a silicon single crystal.

The present invention is completely different in that a single crystal insulator is used as the substrate, rather than a silicon single crystal.

In the conventional SO8 format, a silicon single crystal was grown on a sapphire substrate by thermal decomposition of silane gas, but in this case, if the growth temperature was lowered to 900 tJ, the quality of the resulting silicon film would deteriorate, making it difficult to manufacture MOS devices. It is well known that it is not suitable for

The present invention uses an appropriate metal to select a combination in which the metal-silicon eutectic temperature is lower than the conventional SO8 formation temperature, and forms silicon 1) on a single crystal insulator substrate despite the low temperature.
The purpose of the present invention is to form a silicon single crystal film, and to provide a silicon single crystal film with small residual strain and few crystal defects.

A metal with a eutectic temperature lower than the conventional SOS formal temperature.
The existence of a combination of silicon can be easily found from the metal-silicon solid solution phase diagram, but in order to obtain a good silicon single crystal film, the eutectic temperature must be low. The object of the present invention cannot be easily achieved only by this method. Money(
Au), silver (Ag), aluminum (Al) + platinum (Pt), etc. form a good intermediate layer with silicon and cause a eutectic reaction (G, '0ttaviari, et
al.

:Phys, 1lev, I, att, , 44284
(1980)), but the present inventors are 1 gold, silver,
It was confirmed that the eutectic temperature when aluminum and platinum undergo a eutectic reaction with silicon is lower than the conventional SO8 formation temperature, and the above metals were selected as the metals referred to in the claims of the present invention.

Furthermore, according to Patent No. 55-84752, it is stated that control of precipitation nuclei is important in order to obtain a silicon film with good crystallinity in a silicon single crystal film formation method using a metal-silicon eutectic reaction. There is. Patent 55-84752
This is a formation method in which a metal that causes a eutectic reaction with silicon is first vapor-deposited in the form of islands on a single-crystal insulator substrate, and then silicon is deposited at a desired growth temperature to obtain a silicon single-crystal film.

The present invention first deposits an amorphous or polycrystalline silicon film in the form of islands on a single-crystal insulator substrate, then evaporates a metal that causes a eutectic reaction with silicon onto the substrate, and then heats it to a desired temperature. This is a method of heat treatment, and is disclosed in Patent No. 55-847.
It was found that the controllability in the formation of a silicon iris crystal shape was superior to that of No. 52, and a silicon single crystal film with good crystallinity could be provided. Even if amorphous or polycrystalline silicon is deposited on the entire surface of a single-crystal insulator substrate, a metal that causes a eutectic reaction is then vapor-deposited, and then a heat treatment is performed, the precipitation nuclei are not controlled, so there is no gain. The resulting silicon film only has an increased grain size and is of poor quality.

The present inventor deposits silicon in the form of islands on a single-crystal insulator substrate and controls the precipitation nuclei generated as a result of the metal-silicon eutectic reaction, thereby obtaining a uniform and high-quality silicon single-crystal film. We have discovered that this is possible, and have arrived at the present invention.

Hereinafter, the details of the present invention will be explained by showing examples and referring to the drawings. Examples of single-crystal insulator substrates used for
An explanation will be given by taking a sapphire single-crystal substrate having a 2) plane as an example.

FIG. 1 is a schematic cross-sectional view of a (1ro2)-plane sapphire substrate l on which an amorphous or silicon film 2 is deposited in the form of an island. The surface of the (IToz)-plane sapphire substrate is mirror-finished, and the
Degreasing was performed using setone and ethyl alcohol, and the surface was further cleaned with a mixture of hydrogen peroxide, aqueous ammonia, and pure water. After that, commercially available CVD
(Chemical Vapor Deposition
) equipment to deposit amorphous or polycrystalline silicon and fabricate it into islands using conventional masking techniques. Other vapor deposition methods can be used for depositing the silicon film, and the present invention is not subject to any restrictions on the method of depositing the silicon film.

The silicon film 2 is rectangular, and its width W is 5°10
, 20 and 50 μm were selected. Further, the interval between adjacent silicon films was set to W=L.

FIG. 2 is a diagram schematically representing the plan view of FIG. 1.

In FIG. 2, for the width W of the silicon film 2, values of 0.5 and 1.2 were selected as the value of W/W. Note that the thickness t of the silicon film 2 was 0.4 μm.

FIG. 3 is a diagram schematically showing a cross-sectional view of the substrate after metal film deposition. A metal film 3 that causes a eutectic reaction with silicon was deposited on a sapphire substrate 1 having a silicon film 2 using a commercially available metal deposition apparatus at a pressure of 10 to 10'orr and at room temperature.

The thickness d of the deposited metal film 3 depends on the subsequent heat treatment and the metal species used, and it is necessary to deposit an amount that satisfies a composition ratio that causes a eutectic reaction with silicon. Next, the substrate was inserted into a resistance heating furnace in an inert atmosphere of argon (Ar) gas and subjected to heat treatment.

FIG. 4 schematically shows a cross-sectional view of a substrate from which the metal film transferred by the eutectic reaction was removed by selective etching.

According to this example, gold (A
LL, the metal film thickness is 5ooA, and the heat treatment temperature is the eutectic point temperature. S E M (Scmnning El
eetronMioroseope), T E
M (Trarusmision Electron
When examined using a microscope) and X-ray diffraction, it was revealed that it was single crystal silicon.

The crystallographic orientation of the silicon single crystal film 4 grown on the (1-02)-plane sapphire substrate 1 is <100>, which is similar to the conventional SO
Similarly to 8, (100
)-plane silicon single crystals were found to grow.

According to this example, it became clear from the results of SEM, TEM, and X-ray diffraction that a silicon single crystal film with good crystallinity was grown even when W was 5.20.50 μm. In addition, as a metal, silver (AgL aluminum (
It has become clear that a silicon single crystal film can be grown even when using AA or platinum (PL).

In the above explanation, an example of a (1-02) plane sapphire substrate was shown as the single-crystal insulator substrate used, but the (0001
When a )-plane sapphire substrate was used, a (10)-plane silicon single crystal film was grown. A silicon single crystal film was also grown using a spinel substrate.

In this example, a resistance heating furnace was used as the heat treatment method, but other high frequency induction heating furnaces may be used. Optical heating may also be used, and results similar to those of this example were obtained.

Similar results were obtained when a gas other than argon (Ar 2 ) and t-helium (1%) was used as the atmosphere during the heat treatment. In addition, using a commercially available rotary pump,
Similar results were obtained even when heat treatment was performed in a vacuum of about 10 Torr.

As mentioned above, by using a metal that causes a eutectic reaction with silicon, a single-crystal silicon film with few defects that reduce crystallinity is formed on a single-crystal insulator substrate at a temperature lower than the conventional SO8 formation temperature. showed how to obtain

The present invention uses SO8 as gate OS de) (when using it for chair production,
This method takes advantage of the fact that the silicon film does not necessarily need to be deposited on the entire surface of the substrate. By depositing silicon in the form of islands during the eutectic reaction process, the precipitation nuclei are controlled and uniform, high-quality islands are formed. The present invention provides a new method for forming monocrystalline silicon films.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view illustrating how a silicon film is deposited in an island shape on an (IrO2) plane sapphire substrate. FIG. 2 is a schematic plan view illustrating how a silicon film is deposited in an island shape on a (ITO2) facing 7-iron substrate. FIG. 3 is a schematic cross-sectional view illustrating how a metal film is deposited on a sapphire substrate. FIG. 4 is a diagram schematically showing a cross section of a single crystal silicon film grown in an island shape on a sapphire substrate. 1... (xro2) plane sapphire substrate 2...
... Island-like silicon film 3 ... Vapor-deposited metal film 4 ... Island-like single crystal silicon film

Claims (1)

[Claims] In a method of forming a silicon single crystal film on a single crystal insulating substrate, an amorphous or polycrystalline silicon film is first deposited in the form of islands on the top surface of a single crystal insulating substrate, and then gold, silver,
A metal film made of at least one of aluminum and platinum is deposited, and then the substrate is subjected to heat treatment in an inert gas atmosphere or in vacuum to form an island-shaped silicon single crystal film. Silicon single crystal film formation method.