JPH11228296A - Single crystal silicon carbide and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a single crystal SiC by which the SiC can be efficiently grown to provide a good quality single crystal not having not only a micropipe defect but also lattice distortion and lattice defect by a heat treatment at a low temperature for a short time, and utilization as a semiconductor material and expansion of applicability is promoted. SOLUTION: A β-SiC layer 3 is formed on the surface of an cr-SiC single crystal substrate 1 through a hydrogen ion-containing layer 2' by a thermal CVD method, and the obtained composite body M is subjected to a heat treatment at 2,000-2,200 deg.C to convert a polycrystal body of the β-SiC layer 3 to the α-SiC, and orient the converted α-SiC to the same bearing as the crystal axis of the α-SiC single crystal substrate 1, and to integrally grow the α-SiC single crystal.

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, a high-temperature semiconductor electronic device, a semiconductor substrate wafer of a power device, and a method of manufacturing the same. It is about.

[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.

Incidentally, as a method of growing (manufacturing) this kind of SiC single crystal, conventionally, it is generally known as an industrial method for producing an SiC abrasive, a seed crystal base material is placed on the outer periphery of a high-frequency electrode from its periphery. A large number of nuclei are generated at the center of the seed crystal base material by heating at the center, and a plurality of spiral crystal growths are advanced around the center of the seed crystal base material. Powdered SiC
A sublimation recrystallization method for growing a crystal on a single crystal nucleus by using as a raw material is known.

[0004]

However, among the above-mentioned conventional manufacturing methods, the Acheson method is a method in which a single crystal grows slowly by heating a seed crystal substrate over a long period of time. When the speed is 1 μm / hr. In the sublimation recrystallization method using the powdery SiC produced by the Acheson method as a raw material, the sublimation raw material itself contains impurities. When a pinhole having a diameter of several microns penetrates in a crystal growth direction, which penetrates into a crystal and is called a micropipe defect and causes a leakage current when a semiconductor device is manufactured, etc.
There is a problem that about 1000 / cm ^{2 is} likely to remain in the grown crystal, and it is not possible to obtain a sufficient material in terms of quality. As described above, this is more than that of existing semiconductor materials such as Si and GaAs. Although it has excellent features, it is a factor that prevents its practical application and applicability.

The present applicants have proposed α-methods for solving the technical problems of the Acheson method and the sublimation recrystallization method.
Β-S on the surface of SiC single crystal substrate by thermochemical vapor deposition
After forming the iC layer, the complex is heat-treated to phase-change (convert) the polycrystalline body of the β-SiC layer into α-SiC and oriented in the same direction as the crystal axis of the α-SiC single crystal base material. Single crystal Si that is integrated to grow single crystal
A method for manufacturing C has already been proposed.

The above-mentioned single crystal S already proposed by the present applicants
According to the iC manufacturing method, the crystal growth rate is faster than that of the conventional Acheson method or sublimation recrystallization method, and the generation of micropipe defects due to the generation of crystal nuclei and the diffusion of impurities can be extremely reduced. However, in order to obtain a high-purity single crystal, an α-SiC single crystal substrate and β-Si grown on a surface thereof by a thermochemical vapor deposition method and grown into a polycrystalline body are used.
It is necessary to heat-treat the C layer at a very high temperature of 2200 to 2300 ° C. for a long time (20 hours or more), so that the bonding between Si atoms and C atoms is generated by the heat energy during the high-temperature heat treatment. Decomposition, such as breakage due to inability to withstand lattice vibrations, easily leads to defects in the SiC lattice due to lattice distortion and vacancies of atoms, and there is still room for improvement in the growth of high-quality single crystals.

[0007] The present invention has been made in view of the above-mentioned circumstances, and it is possible to efficiently grow a very high-quality single crystal not only having micropipe defects but also lattice distortion and lattice defects by low-temperature and short-time heat treatment. Single crystal S that can promote practical application as semiconductor material and expansion of applicability
It is intended to provide an iC and a method for manufacturing the same.

[0008]

In order to achieve the above object, a single-crystal SiC according to the first aspect of the present invention has an α-crystal.
By heat-treating the composite formed by forming a β-SiC layer on the surface of a SiC single crystal base material through a hydrogen ion-containing layer by a thermochemical vapor deposition method, the polycrystalline body of the β-SiC layer is converted to α. And a single crystal is grown integrally while being converted into -SiC and oriented in the same direction as the crystal axis of the α-SiC single crystal base material. The method for producing single crystal SiC is to form a hydrogen ion-containing layer on the surface of an α-SiC single crystal base material, and then to form β-S on the surface of the hydrogen ion-containing layer by thermochemical vapor deposition.
forming an iC layer and then heat treating the composite to form the β
The method is characterized in that the polycrystalline body of the -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 integrate and grow the single crystal.

That is, both the invention described in claim 1 and the invention described in claim 4 are directed to the surface of the α-SiC single crystal substrate and the β-Si film formed on the surface by the thermochemical vapor deposition method.
A hydrogen ion-containing layer is interposed at the interface with the C layer, and most of the hydrogen ions in this layer are present in the gaps of the SiC lattice to give a strain to the atomic arrangement of SiC, and the atomic movement of the distorted bond is caused. And the movement of atoms in other inconsistent portions (eg, grain boundaries) are promoted. When the composite is heat-treated in such a state, the heat energy applied at the time of the heat treatment matches the above-mentioned atom transfer, that is, the Si atoms and the C atoms that stabilize the atomic arrangement of the strained SiC lattice. The movement of atoms will occur quickly. This promotes rearrangement of the SiC lattice to the most stable position of Si and C atoms while eliminating distortion of the SiC lattice by low-temperature and short-time heat treatment. S by hole
It is possible to obtain high-quality single-crystal SiC having no defects in the iC lattice with high thermal efficiency.

Here, as the hydrogen ion-containing layer,
The thin β formed on the surface of the α-SiC single crystal substrate by a thermochemical vapor deposition method as described in claim 2 and claim 5.
-Formed by implantation of hydrogen ions into the SiC layer, or as described in claim 3 and claim 6,
Any of those formed on the surface portion of the α-SiC single crystal substrate by directly implanting hydrogen ions into the surface of the -SiC single crystal substrate may be used.

Further, in the method for producing single-crystal SiC according to the invention described in claim 4, as in claim 7, the α-SiC single-crystal substrate has a rectangular α-S
By using a plurality of iC single crystals arranged in close contact with each other, a sufficient size is secured in terms of area and volume, and the above-mentioned high-quality single crystal SiC is produced on an industrial scale. And can be manufactured stably.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 are schematic views illustrating an example of a method of manufacturing a single crystal SiC according to the present invention in the order of manufacturing steps. FIG. 1 shows a first film forming step, and the vertical and horizontal dimensions are 10 mm × 10 mm by Acheson method. A surface 1a of a hexagonal (6H type, 4H type) α-SiC single crystal substrate 1 cut out into a flat plate having a thickness of 0.5 mm and polished to a mirror surface having a surface roughness of 500 Å RMS. Then, a cubic β-SiC layer 2 having a thickness of 50 μm is formed on the surface 1a by a thermochemical vapor deposition method in a hydrogen stream at a temperature range of 1200 to 1500 ° C. (preferably 1400 ° C.). When the β-SiC layer 2 is formed, a reaction gas of SiCl ₄ and CH ₃ is supplied to the deposition unit for an initial 5 minutes.

A 10 μm thick portion of the surface of the β-SiC layer 2 is polished to a mirror surface having a surface roughness of RMS 500 angstroms using diamond particles, and a voltage applied to the surface by a plasma sputtering type ion implantation apparatus. By implanting hydrogen ions H ⁺ at 4 MeV as shown in FIG. 2, a hydrogen ion-containing layer 2 ′ is formed. Here, implantation of hydrogen ions H ⁺ is performed at a dose of 5 × 10
^When the applied voltage is adjusted to about ^{14 to} 5 × 10 ¹⁵ ions / cm ² , the peak of the concentration distribution of hydrogen atoms becomes α-Si.
It is controlled to be near the interface with the surface 1a of the C single crystal substrate 1.

After hydrogen ion implantation, SiCl ₄ and H ₂
3 is formed on the hydrogen ion-containing layer 2 'by a thermochemical vapor deposition method while supplying the .beta.-SiC layer 3 to the vapor deposition section (second film forming step). To obtain a complex M as shown in FIG.

Thereafter, the whole of the above-mentioned composite M is placed in a saturated steam atmosphere of Ar and SiC in the range of 2000 to 2200.
The polycrystalline body of the β-SiC layer 3 and the polycrystalline body of the β-SiC layer 2 forming the hydrogen ion-containing layer 2 are converted into α-SiC by performing a heat treatment in a temperature range of 2 ° C., preferably 2175 ° C. While being converted, it is oriented in the same direction as the crystal axis of the α-SiC single crystal substrate 1 and integrated with the single crystal of the substrate 1 to grow a large single crystal SiC 4 as shown in FIG.

By forming the hydrogen ion-containing layer 2 'on the surface of the α-SiC single crystal substrate 1 as described above, the hydrogen ions H which are mostly present in the gaps of the SiC lattice
^{The +} distorts the atomic arrangement of SiC, and promotes the coordination between the atom movement of the distorted bonding portion and the atom movement of another inconsistent portion (for example, a grain boundary). In this state, by heat-treating the composite M on which the β-SiC layer 3 is formed by the thermochemical vapor deposition method, the hydrogen ions H ⁺ escape from the gaps of the SiC lattice to the outside, and the atoms of the strained SiC lattice are distorted. The movement of the Si atoms and the C atoms in order to stabilize the arrangement is actively generated. Thereby, at a low temperature of about 2175 ° C. and 5
The short-time heat treatment for about a short time eliminates the distortion of the SiC lattice and promotes the rearrangement of the SiC lattice to the most stable positions of Si atoms and C atoms. That is, the strained SiC lattice is rearranged into an unstrained single crystal, and a high-quality single-crystal Si without defects in the SiC lattice due to strain or vacancies of atoms as well as micropipe defects over almost the entire surface.
C4 can be obtained efficiently.

FIG. 5 is a schematic view for explaining another example of the method for producing single-crystal SiC according to the present invention. In this example, the α-SiC single-crystal substrate 1 is processed into a rectangular shape. A plurality of α-SiC single crystals 1A are juxtaposed in a close contact state (with no gap), and β is formed on the surface thereof by a thermochemical vapor deposition method via a hydrogen ion-containing layer 2 ′ in the same manner as described above.
After forming the SiC layer 3, the composite M is heat-treated in the same manner as described above. In this case, the composite M has a sufficient size in terms of area and volume, and Thus, high-quality single crystal SiC4 can be stably produced on an industrial scale.

When a 6H type α-SiC single crystal substrate 1 is used, β-S
The single crystal converted from the polycrystal of the iC layer 2 to α-SiC is easily grown in the same form as the 6H-type single crystal.
When the 4H-type single crystal substrate 1 is used, a single crystal having the same form as the 4H-type single crystal is easily grown by the heat treatment.

In each of the above-described manufacturing methods, the hydrogen ion-containing layer 2 ′ is formed on the surface 1 a of the α-SiC single crystal substrate 1.
Β-SiC layer 2 formed by thermal chemical vapor deposition
Is formed by implanting hydrogen ions into the surface of the α-SiC single crystal substrate 1 by directly implanting hydrogen ions H ⁺ into the surface 1 a of the α-SiC single crystal substrate 1. May be performed.

[0020]

As described above, according to the first and fourth aspects of the present invention, the surface of the α-SiC single crystal substrate and the surface thereof are formed by the thermochemical vapor deposition method. Β
-By interposing a hydrogen ion-containing layer at the interface with the SiC layer, hydrogen ions existing in the gaps of the SiC lattice give distortion to the atomic arrangement of SiC, and the atomic movement of these distorted bonds and other mismatches By preparing a state in which the coordination with the atom transfer of a portion (for example, a grain boundary) is promoted, and by heat-treating the composite in such a state, the coordination of the above-mentioned atom transfer is performed by the heat energy applied at the heat treatment. In other words, it is possible to quickly generate the movement of the Si atoms and the C atoms for stabilizing the atomic arrangement of the strained SiC lattice. As a result, the strain of the SiC lattice is eliminated by a low-temperature and short-time heat treatment,
The C lattice promotes rearrangement of the most stable Si atoms and C atoms to the position, so that high-quality single-crystal Si free from defects in the SiC lattice due to micropipe defects as well as strain and vacancies of atoms.
There is an effect that C can be obtained very efficiently. As a result, the practical use of single crystal SiC, which is superior in existing semiconductor materials such as Si (silicon) and GaAs (gallium arsenide), has high capacity, high frequency, withstand voltage and environmental resistance and is expected as a semiconductor material for power devices And the applicability can be expanded.

In particular, according to the seventh aspect of the present invention, it is possible to increase the area of the high quality single crystal SiC obtained by the first and fourth aspects of the present invention, and to further improve its applicability. Expansion can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a state in which a first film forming step is completed in a manufacturing step for explaining an example of a method for manufacturing single crystal SiC according to the present invention.

FIG. 2 is a schematic view showing a state in which hydrogen ion implantation has been completed in the manufacturing process.

FIG. 3 is a schematic view showing a state in which a second film forming step in the manufacturing process is completed.

FIG. 4 is a schematic diagram showing a manufactured single crystal SiC.

FIG. 5 is a schematic diagram showing a state in which a second film forming step is completed in a manufacturing step for explaining another example of the method for manufacturing a single crystal SiC according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 α-SiC single crystal base material 1A rectangular α-SiC single crystal 1a surface 2 ′ hydrogen ion-containing layer 3 β-SiC layer 4 single crystal SiC M composite

Claims (7)

[Claims] 1. A composite comprising a β-SiC layer formed on a surface of an α-SiC single crystal base material by a thermochemical vapor deposition method via a hydrogen ion-containing layer through a hydrogen ion-containing layer, whereby the β-S
A single crystal SiC, wherein the polycrystal of the iC layer is converted to α-SiC and the single crystal is grown integrally by being oriented in the same direction as the crystal axis of the α-SiC single crystal base material. 2. The hydrogen ion-containing layer is formed by implanting hydrogen ions into a thin β-SiC layer formed on a surface of an α-SiC single crystal substrate by a thermochemical vapor deposition method. Item 2. Single-crystal SiC according to item 1. 3. The method according to claim 1, wherein the hydrogen ion-containing layer is formed by directly implanting hydrogen ions into the surface of the α-SiC single crystal substrate.
The single-crystal SiC according to claim 1, wherein the single-crystal SiC is formed on a surface of a single-crystal SiC substrate. 4. After forming a hydrogen ion-containing layer on the surface of the α-SiC single crystal substrate, a β-SiC layer is formed on the surface of the hydrogen ion-containing layer by a thermochemical vapor deposition method.
Heat treating the composite to convert the polycrystalline body of the β-SiC layer into α-SiC and orienting and growing a single crystal in the same direction as the crystal axis of the α-SiC single crystal base material. A method for producing single-crystal SiC, comprising: 5. The hydrogen ion-containing layer is formed by implanting hydrogen ions into a thin β-SiC layer formed on a surface of an α-SiC single crystal substrate by a thermochemical vapor deposition method. Item 5. The method for producing single-crystal SiC according to Item 4. 6. The method according to claim 1, wherein the hydrogen ion-containing layer is formed by direct injection of hydrogen ions into the surface of the α-SiC single crystal base material.
The method for producing a single-crystal SiC according to claim 4, wherein the single-crystal SiC is formed on a surface of a single-crystal SiC base material. 7. The single crystal according to claim 4, wherein the α-SiC single crystal substrate is formed by arranging a plurality of rectangular α-SiC single crystals in close contact with each other. Manufacturing method of crystalline SiC.