Seed crystal for SiC single-crystal growth, SiC single crystal, and method of manufacturing the SiC single crystal

1. A seed crystal for SiC single-crystal growth, comprising:

a facet formation region containing a {0001}-plane uppermost portion; and

n (n>=3) planes enclosing the periphery of the facet formation region, wherein:

the facet formation region includes a region ranging from the center of gravity of the {0001}-plane uppermost portion to any point corresponding to a radius r being R/5 where R is a diameter of a circumscribed circle of the seed crystal for SiC single-crystal growth;

the seed crystal for SiC single-crystal growth satisfies the relationships represented by formulas (a) to (c),

B k k-1 <=cos −1 (sin(2.3 degrees)/sin C k )  (a),

B k k <=cos −1 (sin(2.3 degrees)/sin C k )  (b),

min( C k )<=20 degrees  (c),

where C k is an offset angle of a k-th plane, B k k-1 is an angle defined by an offset downstream direction of the k-th plane and a (k−1)-th ridge line, and B k k is an angle defined by the offset downstream direction of the k-th plane and a k-th ridge line;

by satisfying the relationships represented by formulas (a) and (b), an angle defined by the (k−1)-th ridge line and the {0001} plane is 2.3 degrees or more so that no c-plane facet is formed on the (k−1)-th ridge line and an angle defined by the k-th ridge line and the {0001} plane is 2.3 degrees or more so that no c-plane facet is formed on the k-th ridge line; and

a diameter of the circumscribed circle of the seed crystal for SiC single-crystal growth is 100 mm or more.

2. The seed crystal for SiC single-crystal growth according to claim 1 , wherein the seed crystal for SiC single-crystal growth is cut out from an SiC single crystal grown with a growth plane being a plane having an offset angle of 60 to 90 degrees from the {0001} plane.

3. The seed crystal for SiC single-crystal growth according to claim 1 , further comprising a screw dislocation formable region that allows screw dislocations to be formed at a higher density in the neighborhood of the {0001}-plane uppermost portion than on an offset downstream side.

4. The seed crystal for SiC single-crystal growth according to claim 1 , wherein the {0001}-plane uppermost portion is provided in the neighborhood of an end of the seed crystal for SiC single-crystal growth.

5. The seed crystal for SiC single-crystal growth according to claim 1 , wherein at least one of the n planes has an offset angle C different from that of any of the other n planes.

6. The seed crystal for SiC single-crystal growth according to claim 1 ,

wherein the {0001}-plane uppermost portion is a dotted portion, and

the {0001}-plane uppermost portion corresponds to a position of a screw dislocation within the seed crystal for SiC single-crystal growth.

7. The seed crystal for SiC single-crystal growth according to claim 1 , wherein any of the k-th planes (k=1, 2, n) has an offset angle C k of 8 degrees or less.

8. The seed crystal for SiC single-crystal growth according to claim 1 , wherein a k-th plane having the largest area among the n planes has an offset angle C k of 4 degrees or less.

9. A method of manufacturing an SiC single crystal, comprising a growth step of growing an SiC single crystal on a growth plane of the seed crystal for SiC single-crystal growth according to claim 1 .

10. An SiC single crystal, wherein a maximum dimension (d) of a {0001}-plane facet in an initial stage of crystal growth, at a position slightly inside a grown crystal from an interface between the seed crystal for SiC single-crystal growth and a grown crystal, is ⅕ or less of a diameter (D) of the grown crystal in the initial stage of crystal growth, and the diameter (D) is 4 inches (101.6 mm) or more.