Group III nitride composite substrate and method for manufacturing the same, laminated group III nitride composite substrate, and group III nitride semiconductor device and method for manufacturing the same

Abstract

A group III nitride composite substrate with a diameter of 75 mm or more includes a support substrate having a thickness ts of 0.1 mm or more and 1 mm or less and a group III nitride film having a thickness tf, thinner than the thickness ts, of 0.01 mm or more and 0.25 mm or less that are bonded to each other. An absolute value |Δα| of a difference Δα in thermal expansion coefficient determined by subtracting a thermal expansion coefficient αs of the support substrate from a thermal expansion coefficient αf of the group III nitride film is 2.2×10−6 K−1 or less. A Young's modulus Es and the thickness ts of the support substrate, a Young's modulus Ef and the thickness tf of the group III nitride film, and the difference Δα in thermal expansion coefficient satisfy a relation: ts2/tf≧6Ef·|Δα|/Es.

Dependencies are inferred from the claim text.