US 11,718,927 B2
Group III nitride crystal substrate having a diameter of 4 inches or more and a curved c-plane with a radius of curvature of 15 m or more
Takehiro Yoshida, Ibaraki (JP); Masatomo Shibata, Ibaraki (JP); Seiji Sarayama, Ibaraki (JP); Takashi Sato, Ibaraki (JP); Naoya Miyoshi, Ibaraki (JP); and Akishige Murakami, Ibaraki (JP)
Assigned to SUMITOMO CHEMICAL COMPANY, LIMITED, Tokyo (JP)
Filed by SUMITOMO CHEMICAL COMPANY, LIMITED, Tokyo (JP)
Filed on Mar. 14, 2019, as Appl. No. 16/353,115.
Claims priority of application No. 2018-053120 (JP), filed on Mar. 20, 2018.
Prior Publication US 2019/0292682 A1, Sep. 26, 2019
Int. Cl. C30B 29/40 (2006.01); C30B 25/20 (2006.01); C30B 25/10 (2006.01); C30B 25/08 (2006.01)
CPC C30B 25/20 (2013.01) [C30B 25/08 (2013.01); C30B 25/10 (2013.01); C30B 29/406 (2013.01)] 3 Claims
OG exemplary drawing
 
1. A crystal substrate which is a substrate consisting of a single crystal of group III nitride, having a diameter of 4 inches or more, and in which c-plane of the single crystal is curved in a concave spherical shape toward inside of the substrate, when a main surface of the substrate is viewed from +c side with a radius of curvature of 15 m or more, the c-plane of the single crystal has a constant radius of curvature in a region of 80% or more of an area of the main surface viewed in plan view, and the substrate consists of a single domain,
wherein a thickness of the substrate is 0.2 mm or more, and
wherein the radius of curvature of the c-plane of the single crystal in a-axis direction is 27.2 m or more and the radius of curvature of the c-plane of the single crystal in m-axis direction is 35.6 m or more.