JPH05201795A - Production for single crystal grain - Google Patents

Abstract

PURPOSE:To provide a producing method for a single crystal grain able to grow e.g. a large sized single crystal grain such as diamond with a substrate inexpensive and easy to obtain. CONSTITUTION:In the producing method for the single crystal grain by the vapor phase synthesis, after the 1st growth by growing a polycrystalline body on the substrate by the vapor phase synthesis, the single crystal grain 12 is separated from the polycrystalline body and the 2nd growth by growing the single crystal grain 12 on the growing surface in the 1st growth by the vapor phase synthesis is executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing single crystal grains by a vapor phase synthesis method.

[0002]

2. Description of the Related Art In such a single crystal grain manufacturing method, a diamond single crystal is formed on a semiconductor single crystal substrate such as a Si single crystal substrate by a vapor phase synthesis method such as a high frequency plasma CVD method or a microwave plasma CVD method. A method of synthesizing grains has been considered. This method can synthesize diamond using a cheap and easily available substrate.

[0003]

However, in the above-described method for producing a single crystal grain, innumerable single crystal grains are brought into close contact with each other on the single crystal substrate and grow into a film form to become a polycrystalline body. Since the grains interfere with each other in the growth in the direction parallel to the growth plane, there is a disadvantage that one single crystal grain cannot be grown alone to a size that can be applied to a semiconductor or the like. .. The present invention has been made in view of the above circumstances, and an object thereof is to provide a single crystal grain manufacturing method capable of growing large single crystal grains while using an inexpensive and easily available substrate. Especially.

[0004]

The method for producing single crystal grains according to the present invention is based on a vapor phase synthesis method, and the first feature is that a polycrystalline body is grown on a substrate by the vapor phase synthesis method. 1
After the growth of, the single crystal grains are separated from the polycrystal, and the single crystal grains are further grown on the growth surface in the first growth by the vapor phase synthesis method to perform the second growth. .. A second feature of the present invention is to limit the embodiment of the first feature, wherein the substrate is made of Si single crystal,
The point is to synthesize a diamond polycrystal on the (100) plane of the substrate.

[0005]

According to the first feature described above, after growing a polycrystal on the substrate by the vapor phase synthesis method, single crystal grains forming the polycrystal on the substrate are removed by, for example, plasma etching or chemical etching. Separate into single crystal grains. The separated single crystal grains are arranged on the growth surface in the first growth in the direction of further growth and grown again by the vapor phase synthesis method. In the case of the growth in the polycrystalline body as it is, it grows in the direction normal to the growth surface, but in the growth in the direction parallel to the growth surface, the single crystal grains in the polycrystalline body collide with each other and hinder the growth. As a matter of fact, by separating the single crystal grains as described above, the obstacle can be eliminated, and while utilizing the growth surface in the polycrystalline state in the first growth, by the second growth, Not only can the height of the crystal in the direction normal to the growth surface be increased, but the area of the growth surface can be increased,
Large single crystal grains can be obtained. According to the second feature, the single crystal grains forming the polycrystalline body of diamond in the first growth grow in the shape of an inverted quadrangular pyramid, so that the second growth effectively grows in the direction parallel to the growth plane. Can be made

[0006]

According to the first feature of the present invention, since a large single crystal grain can be synthesized as described above while using an inexpensive and easily available substrate, the manufacturing cost of the single crystal grain can be reduced. While suppressing as much as possible, it becomes possible to apply the single crystal grain to a semiconductor or the like. According to the second feature,
Since the shape of the single crystal grains forming the diamond polycrystal can be made into an inverted quadrangular pyramid shape, the area of the single crystal grains can be effectively increased, and the single crystal grains are arranged before the second growth. At this time, the growth surface of the first growth and the growth surface of the second growth can be matched simply by forming, for example, a recess on the table to be placed and inserting the tip of the quadrangular pyramid into the recess. Work can be performed easily.

[0007]

Embodiments of the present invention will be described with reference to the drawings.
The microwave plasma CVD apparatus shown in FIG. 1 is an apparatus that performs vapor deposition by a microwave plasma CVD method, which is a type of vapor phase synthesis method. Plasma is generated by microwave energy, and the material gas is dissociated by the plasma. This is an apparatus for depositing the dissociated material on the substrate.

In FIG. 1, a substrate support 2 is arranged in a reaction tube 1, and a microwave generated by a microwave oscillator 3 and guided by a waveguide 4 is supplied to the vicinity of the substrate support 2. To be done. Further, in the reaction tube 1, a gas cylinder 5,
Methane gas as a material gas, hydrogen gas for generating plasma, and argon gas are supplied from 6 and 7, respectively, and the inside of the reaction tube 1 is exhausted from an exhaust port 8 by a vacuum pump 9.

The process of producing single crystal grains of diamond by the above microwave plasma CVD apparatus will be described below. First, the Si single crystal substrate 10 as a substrate is
The reaction tube 1 is placed on the substrate support 2 so that the (100) surface becomes the growth surface, and the inside of the reaction tube 1 is evacuated by the vacuum pump 9. Thereafter, methane gas and hydrogen gas are introduced into the reaction tube 1 from the gas cylinders 5 and 6 while mixing the argon gas from the gas cylinder 7 as needed. When the gas pressure in the reaction tube 1 reaches a predetermined value, microwaves of predetermined power are supplied to the reaction tube 1
To generate plasma. The methane gas is dissociated by this plasma, carbon is deposited on the Si single crystal substrate 10, and the first growth is performed as the polycrystalline diamond 11 as a film-shaped polycrystalline body having a cross section as shown in FIG. At this time, since the Si single crystal substrate 10 is heated by the microwave, no special heating means is required, but if necessary for setting growth conditions, a heater is provided in the substrate support base 2. May be provided to heat the Si single crystal substrate 10.

Next, the polycrystalline diamond 11 on the Si single crystal substrate 10 is subjected to air plasma etching mainly containing N ₂ to remove graphite and poor quality diamond on the surface of the growth substrate. This etching work is performed by adding a N ₂ gas cylinder and an O ₂ gas cylinder to the microwave plasma CVD apparatus described above and performing microwave plasma CVD.
It may be performed by a device or another device.

Then, the Si single crystal substrate 10 that has been subjected to the etching treatment is attached with an etchant containing a mixture of hydrofluoric acid and nitric acid to remove the Si single crystal substrate 10 by etching.
As a result, the polycrystalline diamonds 11 grown on the Si single crystal substrate 10 are separated into pieces, and diamond single crystal grains 12 as single crystal grains are obtained. The shape of the diamond single crystal grains 12 is a quadrangular pyramid whose bottom surface is the growth surface in the first growth as shown in FIG.

Next, the diamond single crystal grains 12 are
As shown in FIG.
With the growth surface in the growth of 1, ie, the bottom surface of the quadrangular pyramid facing upward, the tip of the quadrangular pyramid is inserted and placed on the support base 13.
The small holes 14 of the support base 13 can be easily formed by a general etching technique. The diamond single crystal grains 12 and the support 13 arranged in this way are placed again on the substrate support 2 of the microwave plasma CVD apparatus so that the growth material is supplied in the direction of arrow 15 shown in FIG. Then, similarly to the first growth, the second growth is performed on the diamond single crystal grain. By this second growth, the diamond single crystal grains 12 grow not only in the direction normal to the growth surface but also in the direction parallel to the growth surface because there is no factor that hinders the growth. In this way, large-grain single-crystal diamond that can be used as a semiconductor is obtained.

[Other Embodiments] In the above embodiment, the Si single crystal substrate was used as the substrate 10 and the (100) plane was used as the growth surface. However, other materials such as nickel and sapphire may be used.
Other crystal planes may be used as the growth plane. In addition to the microwave plasma CVD apparatus of the above embodiment, a high frequency plasma CVD apparatus is used as an apparatus used for growing diamond.
An apparatus, a hot filament CVD apparatus, an ion beam vapor deposition apparatus, or the like may be used. In the above examples, the production of single crystal grains of diamond was described, but the present invention is
It can be applied to the production of single crystal grains other than diamond, such as CBN and ruby.

It should be noted that reference numerals are given in the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a microwave CVD apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a growth cross section of a polycrystalline diamond according to an example of the present invention.

FIG. 3 is a diagram showing the arrangement of diamond single crystal grains according to an example of the present invention.

[Explanation of symbols]

 10 substrate 11 polycrystal 12 single crystal grain

Claims (2)

[Claims] 1. A method for producing single crystal grains by a vapor phase synthesis method, the method comprising the steps of: first growing a polycrystalline body (11) on a substrate (10) by the vapor phase synthesis method; Single crystal grain (12) separated from (11), and the single crystal grain (12) is further grown on the growth surface in the first growth by vapor phase synthesis method. Production method. 2. The method for producing single crystal grains according to claim 1, wherein the substrate (10) is made of Si single crystal, and a polycrystalline diamond body (11) is synthesized on the (100) plane of the substrate (10). ..