JPH11147792A - Single crystal silicon carbide and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently grow a large-sized and high-quality single crystal hardly containing micropipe defects and crystal grain boundaries while reducing thermal energy required for the crystal growth. SOLUTION: A composite M prepared by forming an α-2H-SiC layer 2 on the surface of an α-SiC single crystal substrate 1 according to a thermal chemical vapor deposition(CVD) method and transforming the phase of a part of the α-2H-SiC layer 2 into α-6H (or 4H)-SiC is heat-treated at 1,600-2,400 deg.C to thereby convert the whole of the α-2H-SiC layer 2 into α-SiC and orient the resultant α-SiC in the same direction as the crystal axis of the α-SiC single crystal substrate 1. As a result, a single crystal is integrally grown.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single crystal SiC and a method of manufacturing the same, and more particularly, to a single crystal SiC used as a light emitting diode or a substrate wafer of an electronic device, and a method of manufacturing the same.

[0002]

2. Description of the Related Art SiC (silicon carbide) is not only excellent in heat resistance and mechanical strength, but also resistant to radiation. In addition, it is easy to control valence electrons and holes by adding impurities. Has a wide forbidden band (By the way, 6H type S
about 3.0 eV for an iC single crystal and 3.26 eV for a 4H type SiC single crystal), such as Si (silicon) or GaAs.
(Gallium arsenide) and other materials that can not be realized with existing semiconductor materials, can achieve high capacity, high frequency, withstand voltage and environmental resistance, and are attracting attention and expected as next-generation semiconductor materials for power devices I have.

Conventionally, as a method of growing (manufacturing) this kind of SiC single crystal, there is a method of growing a SiC single crystal by a sublimation recrystallization method using a seed crystal, and a method of growing a SiC single crystal on a silicon substrate at high temperature. Chemical vapor deposition (CVD)
There is known a method of growing a cubic SiC single crystal (β-SiC) by performing epitaxial growth using GaN.

[0004]

However, both of the above-mentioned conventional manufacturing methods have a crystal growth rate of 1 μm / hr.
Not only is it extremely low, but also in the sublimation recrystallization method, a pinhole with a diameter of several microns penetrates in the crystal growth direction called micropipe defect, which causes leakage current etc. when manufacturing semiconductor devices Is 100 to 1000 / cm ²
A large number of crystals are present in the grown crystal, which have many excellent characteristics as compared with existing semiconductor materials such as Si and GaAs as described above, but have insufficient crystal quality. This is a factor preventing its practical use.

In the case of epitaxial growth by high-temperature CVD, it is necessary to create a high-purity reducing atmosphere in addition to a substrate temperature as high as 1700 to 1800 ° C., and a structural material that can withstand such conditions is required. There is almost no problem in that it is very difficult in terms of equipment and the growth rate is naturally limited due to epitaxial growth.

The present invention has been made in view of the above circumstances, and can efficiently grow a large and high-quality single crystal having almost no micropipe defects and crystal grain boundaries while requiring less heat energy for crystal growth. Single crystal SiC that can promote practical use as a semiconductor material
And a method for producing the same.

[0007]

In order to achieve the above object, a single crystal SiC according to the first aspect of the present invention has an α-S
α-2H-S on the surface of iC single crystal substrate by thermochemical vapor deposition
By heat-treating the composite formed with the iC layer,
Wherein the α-2H-SiC layer is converted into α-SiC, and is oriented in the same direction as the crystal axis of the α-SiC single crystal base material to grow a single crystal integrally. And the surface of the α-SiC single crystal substrate
By forming an α-2H-SiC layer having a crystal structure having a regularity close to the crystal structure of the C single crystal base material by a thermochemical vapor deposition method, a part of the α-2H-SiC layer is formed during the thermochemical vapor deposition. Is transformed into α-6H (or 4H) -SiC, and the composite is subjected to a heat treatment, so that the heat energy (heat × time) during the heat treatment is small, and the α-2H-SiC layer is formed. Is converted into α-6H (or 4H) -SiC quickly (phase transformation), and is oriented in the same direction as the crystal axis of the α-SiC single crystal base material to be integrated with the single crystal of the base material. Of single crystal SiC is grown. The single-crystal SiC grown in this way has few micropipe defects and crystal grain boundaries, and high-quality single-crystal SiC can be obtained.

[0008] The single crystal S according to the second aspect of the present invention.
iC is the value of α-2 in the configuration of the invention described in claim 1.
The H-SiC layer is formed on the surface of the α-SiC single crystal base material by a thermochemical vapor deposition method in the range of 1300 to 1500 ° C., and a part of the α-2H-SiC layer has a relatively low temperature and Since it is quickly converted into α-SiC and grown into a single crystal by a short-time thermochemical vapor deposition, diffusion of impurity atoms is suppressed, and a high-density material having less impurities and lattice defects than an α-SiC single crystal base material. It is possible to obtain single crystals of purity.

Further, according to a third aspect of the present invention, there is provided a method for producing single crystal SiC, comprising forming an α-2H-SiC layer on a surface of an α-SiC single crystal substrate by a thermochemical vapor deposition method, and then forming a composite thereof. The body is heat-treated to convert the α-2H-SiC layer into α-Si
C, and is oriented and oriented in the same direction as the crystal axis of the α-SiC single crystal substrate to integrate and grow the single crystal. However, large and high-quality single-crystal SiC having almost no micropipe defects and crystal grain boundaries is grown easily and efficiently, and single-crystal SiC that contributes to the practical use as a semiconductor material is stably manufactured on an industrial scale. It is possible to supply.

Further, in the method for producing single-crystal SiC according to the invention of claim 4, the heat treatment temperature of the composite according to the invention of claim 3 is higher than the temperature of thermochemical vapor deposition.
Specifically, as described in claim 5, 1600 to 240
At 0 ° C. and in a saturated vapor pressure of SiC,
High-quality single-crystal SiC can be produced very easily in terms of equipment.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a single crystal Si according to the present invention.
FIG. 2 is a schematic view showing a state before heat treatment of C, in which 1 is a hexagonal (6H type or 4H type) α-SiC;
By forming the α-2H-SiC layer 2 on the surface of the single-crystal base material by a thermal CVD method at a temperature in the range of 1300 to 1500 ° C., α Α-6 due to a partial phase transformation of -2H-SiC layer 2
A composite M in which an H (or 4H) -SiC single crystal is grown is formed.

Thereafter, the entirety of the above-mentioned complex M is 1600
To 2400 ° C., preferably 2000 to 2200 ° C., specifically 2000 ° C. × 5 hours or 2200 ° C.
C. for 4 hours and in a saturated vapor pressure of SiC, a part of which is already α-6H (or 4H) -S
The α-2H-SiC layer 2 growing on the iC single crystal body
Is converted to α-6H (or 4H) -SiC, and is oriented in the same direction as the crystal axis of the α-SiC single crystal substrate 1 to be integrated with the single crystal of the substrate 1 as shown in FIG. Large single crystal SiC5 is grown.

As described above, the α-2H-SiC layer 2 having a crystal structure having a regularity close to the crystal structure of the α-SiC single crystal substrate 1 is formed on the surface of the α-SiC single crystal substrate 1 by thermochemical treatment. A part of the crystal is formed by α-6H (or 4
By subjecting the composite M grown to H) -SiC single crystal to a heat treatment, the surface of the α-SiC single crystal
Compared to the case where the composite in which the SiC (3C-SiC) layer is formed by the thermal chemical vapor deposition method is subjected to the heat treatment, the micropipe defects and the grain boundaries can be obtained only by applying the small heat energy as described above during the heat treatment. Almost no (1cm ²
Less than 10) high quality and large single crystal SiC
Can be manufactured efficiently.

[0014]

As described above, according to the first aspect of the present invention, an α-2H-SiC layer having a crystal structure having a regularity close to that of the α-SiC single crystal base material is formed on the α-SiC single crystal base material by thermochemistry. And a part of the α-2H-SiC layer is formed by α-6H
(Or 4H) -SiC, and then heat-treating the composite to reduce the heat energy (heat × time) required for crystal growth while maintaining α-2H.
-The entire SiC layer is quickly converted to α-6H (or 4H) -SiC (phase transformation), and is oriented in the same direction as the crystal axis of the α-SiC single crystal base, and integrated with the single crystal of the base. A large-sized high-quality single crystal SiC substantially free from micropipe defects and crystal grain boundaries can be efficiently obtained. Thereby, Si (silicon) or GaAs
Compared to existing semiconductor materials such as s (gallium arsenide), the effect of being able to promote the practical use of single crystal SiC which is excellent in large capacity, high frequency, withstand voltage and environmental resistance and expected as a semiconductor material for power devices. To play.

According to the second aspect of the present invention, the single crystal SiC obtained by the first aspect of the present invention can be made into a high-purity single crystal with less impurities and lattice defects.

Furthermore, according to the third aspect of the present invention, high-quality single-crystal SiC having extremely few micropipe defects and crystal grain boundaries according to the first aspect of the present invention can be easily and efficiently grown. In addition, there is an effect that the semiconductor material can be stably supplied on an industrial scale.

Furthermore, according to the fourth and fifth aspects of the present invention, high-quality single-crystal SiC can be produced very easily in terms of equipment.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a state before heat treatment of single crystal SiC according to the present invention.

FIG. 2 is a schematic diagram showing a state after heat treatment of single crystal SiC according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 α-SiC single crystal base material 2 α-2H-SiC layer 5 single crystal SiC M composite

Claims (5)

[Claims] An α-2H-SiC layer is formed on a surface of an α-SiC single crystal base material by a thermal chemical vapor deposition method and heat-treated to form an α-2H-SiC layer. S
A single-crystal SiC, which is converted into iC and is oriented in the same direction as the crystal axis of the α-SiC single-crystal substrate to grow a single crystal integrally. 2. The method according to claim 1, wherein said α-2H-SiC layer is 1300-300.
The single-crystal SiC according to claim 1, wherein the single-crystal SiC is formed on the surface of the α-SiC single-crystal substrate by a thermochemical deposition method in a range of 1500 ° C. 3. An α-2H-SiC layer is formed on the surface of an α-SiC single crystal base material by a thermochemical vapor deposition method, and then the composite is heat-treated to convert the α-2H-SiC layer into an α-SiC layer.
A method for producing single-crystal SiC, wherein the single-crystal SiC is converted into SiC, and oriented in the same direction as the crystal axis of the α-SiC single-crystal substrate to integrate and grow the single crystal. 4. The method for producing single crystal SiC according to claim 3, wherein the heat treatment is performed at a temperature higher than a thermochemical vapor deposition temperature and in a SiC saturated vapor pressure. 5. The heat treatment temperature is from 1600 to 2400.
The method for producing single crystal SiC according to claim 4, wherein the temperature is ° C.