Chemistry of inorganic compounds – Silicon or compound thereof – Binary compound
Patent
1999-04-23
2000-11-07
Utech, Benjamin L.
Chemistry of inorganic compounds
Silicon or compound thereof
Binary compound
117 1, 117 4, 117 7, 117 9, 117 88, 117951, C01B 3136, C30B 104
Patent
active
061432679
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 semiconductor substrate wafer for a light-emitting diode, an X-ray optical element such as a monochrometer, a high-temperature semiconductor electronic element, a power 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 than an existing semiconductor material such as Si (silicon) and GaAs (gallium arsenide), and also has good high-temperature properties, high-frequency properties, dielectric strength, and resistance to environments. In addition, it is easy to perform the 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). For these reasons, single crystal SiC receives attention and is expected as a semiconductor material for a next-generation semiconductor material for a power device.
As a method of producing (growing) single crystal SiC of this type, conventionally, known are the Achison method which is generally known as an industrial method of producing an SiC abrasive material, and the sublimation and recrystallization method in which powder SiC produced by the Achison method is used as a raw material and a crystal is grown on a single crystalline nucleus.
In the Achison method of the above-described conventional production methods, however, a single crystal is grown slowly over a long time period, so that the crystal growth rate is very low. In addition, a large number of crystalline nuclei are generated in an initial growth stage, and they propagate to an upper portion of the crystal as the crystal growth advances. Thus, it is difficult to singly obtain a large-size single crystal.
In the sublimation and recrystallization method, a high-speed growth of about 1 mm/hr. is adopted mainly for an economical reason (production cost), so that impurities and pin holes which have a diameter of several microns and which pass through the crystal in the growing direction are likely to remain in a growing crystal. Such pin holes are called micropipe defects and cause a leakage current when a semiconductor device is fabricated. Accordingly, there exists a problem in that single crystal SiC having a sufficiently good quality cannot be obtained. This blocks a practical use of SiC which has many superior characteristics as compared with other existing semiconductor materials such as Si and GaAs as described above.
DISCLOSURE OF INVENTION
The invention has been conducted in view of the abovementioned circumstances of the prior art. It is an object of the invention to provide single crystal SiC in which the crystal orientation can be easily specified, and which is large and has a very high quality, and a method of producing single crystal SiC in which the growing rate of single crystal SiC is made higher so that a single crystal having a high quality can be produced with a high productivity.
The single crystal SiC of the first invention is characterized in that a complex in which plural plate-like single crystal SiC pieces are stacked while crystal orientation faces of the SiC pieces are arranged in a substantially same plane and crystal orientations are unified into one direction, and a polycrystalline plate consisting of Si and C atoms is stacked on the crystal orientation faces of the plural stacked single crystal SiC pieces is subjected to a heat treatment, whereby a single crystal is grown from the crystal orientation faces of the plural single crystal SiC pieces toward the polycrystalline plate.
The method of producing single crystal SiC of the second invention is characterized in that plural plate-like single crystal SiC pieces are stacked while crystal orientation faces of the SiC pieces are arranged in a substantially same plane and crystal orientations are unified into on
REFERENCES:
patent: 5915194 (1999-06-01), Powell et al.
patent: 6053973 (1999-06-01), Tanino et al.
Champagne Donald L.
Nippon Pillar Packing Co. Ltd.
Utech Benjamin L.
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