Chemistry of inorganic compounds – Silicon or compound thereof – Binary compound
Patent
1998-12-29
2000-11-28
Utech, Benjamin L.
Chemistry of inorganic compounds
Silicon or compound thereof
Binary compound
117 4, 117 7, 117 9, 117951, L30B 104, L30B 2936
Patent
active
061531650
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to single crystal SiC and a method of producing the same, and more particularly to single crystal SiC which is used as a substrate wafer for a light-emitting diode and an electronic device, or the like, and also to a method of producing the same.
BACKGROUND ART
SiC (silicon carbide) is superior in heat resistance and mechanical strength, and also has good resistance to radiation. In addition, it is easy to perform valence control of electrons and holes by doping an impurity. Moreover, SiC has a wide band gap (for example, single crystal 6H-SiC has a band gap of about 3.0 eV, and single crystal 4H-SiC has a band gap of 3.26 eV). Therefore, it is possible to realize a large capacity, high frequency, high dielectric strength, and high environmental resistance which cannot be realized by existing semiconductor materials such as Si (silicon) and GaAs (gallium arsenide). For these reasons, single crystal SiC is receiving attention and is expected as a semiconductor material for a next-generation power device.
As a method of growing (producing) single crystal SiC of this type, known are a method in which single crystal SiC is grown by a sublimation and recrystallization method using a seed crystal, and that in which, in the case of a high temperature, epitaxial growth is conducted on a silicon substrate by using a chemical vapor deposition method (CVD method), thereby growing single crystal cubic SiC (.beta.-SiC).
In the above-described conventional production methods, however, the crystal growth rate is as low as 1 .mu.m/hr. Furthermore, the sublimation and recrystallization method has a problem in that pin holes which have a diameter of several microns and which pass through the crystal in the growing direction remain at about 100 to 1,000/cm.sup.2 in a growing crystal. Such pin holes are called micropipe defects and cause a leakage current when a semiconductor device is fabricated. These problems block a practical use of single crystal SiC which has superior characteristics as compared with other existing semiconductor materials such as Si and GaAs as described above.
In the case of the high-temperature CVD method, the substrate temperature is as high as 1,700 to 1,900.degree. C., and it is required to produce a high-purity reducing atmosphere. Therefore, the method has a problem in that it is difficult to conduct the method from the view point of installation. Furthermore, the method has another problem in that, because of epitaxial growth, the growth rate is naturally limited.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide single crystal SiC of a high quality in which lattice defects and micropipe defects are largely reduced by conducting a high-temperature heat treatment, and a production method in which the growth rate of the single crystal SiC is enhanced so that the area of the single crystal is sufficiently ensured, and which can expedite the practical use of the single crystal as a semiconductor material.
The single crystal SiC of the present invention is characterized in that a complex in which a polycrystalline plate consisting of Si and C atoms is stacked on the surface of a single crystal SiC base material and is subjected to a heat treatment, whereby polycrystals of the polycrystalline plate are transformed into a single crystal and the single crystal oriented in the same direction as the crystal axis of the single crystal base material is grown.
According to the thus configured present invention, the complex consisting of the single crystal SiC base material and the polycrystalline plate stacked on the surface of the base material is subjected to a heat treatment at a high temperature, whereby polycrystals of the polycrystalline plate are phase-transformed while external impurities are prevented from entering between the single crystal SiC base material and the polycrystalline plate, and the crystal is oriented in the same direction as the crystal axis of the single crystal SiC base material and is integrated with
REFERENCES:
patent: 4590130 (1986-05-01), Cline
patent: 5471946 (1995-12-01), Scholz et al.
patent: 6053973 (2000-04-01), Tanino et al.
Champagne Donald L.
Nippon Pillar Packing Co. Ltd.
Utech Benjamin L.
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