Appeal No. 2003-1852
Application No. 09/415,402
The subject matter on appeal relates to a “method of
controlling and encouraging the growth of high quality SiC
single crystals in a SiC crystal growth system” (claims 1, 4, 5,
38, and 40-42), a “method of growing high quality single
crystals of SiC in a SiC crystal growth system” (claims 6, 8-10,
14-16, 18-24), and a “SiC crystal growth system for high
temperature SiC crystal growth” (claims 34-36 and 48-50).
Further details of this appealed subject matter are recited in
representative claims 1 and 48 reproduced below:
1. A method of controlling and encouraging the
growth of high quality SiC single crystals in a SiC
crystal growth system, the method comprising
directing and maintaining a flow of silane and
carbon source gas to a reaction area while heating the
silane and the carbon source gas to approximately the
reaction temperature;
reacting the silane and the carbon source gas in
the reaction area to form a vaporized species
containing carbon and silicon;
directing and maintaining a flow of the vaporized
species containing carbon and silicon to a SiC seed
crystal under conditions of temperature and pressure
at which single crystal growth of silicon carbide will
take place upon the seed crystal;
substantially preventing the silane from reacting
with ambient surroundings other than the carbon source
gas by introducing the silane into a SiC crystal
growth system comprising graphite that is coated with
a material characterized by a melting point above the
sublimation temperature of SiC, chemical inertness
with respect to silicon and hydrogen at the
sublimation temperature, and a coefficient of thermal
expansion sufficiently similar to the graphite to
prevent cracking between the graphite and the coating
at the sublimation temperature.
2
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