GROUP III NITRIDE COMPOSITE SUBSTRATE AND MANUFACTURING METHOD OF THE SAME, LAMINATED GROUP III NITRIDE COMPOSITE SUBSTRATE, AND GROUP III NITRIDE SEMICONDUCTOR DEVICE AND MANUFACTURING METHOD OF THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a group III nitride composite substrate which has a group III nitride film having a large film thickness and high crystal quality, and achieves low cost, a large diameter and low distortion; and provide a group III nitride semiconductor device manufactured by using the group III nitride composite substrate.SOLUTION: A group III nitride composite substrate 1 has a diameter of 75 mm and over in which a support substrate 11 with a thickness tof not less than 0.1 mm and not more than 1 mm and a group III nitride film 13 with a thickness tof not less than 0.01 mm and not more than 0.25 mm which is thinner than the thickness t. An absolute value |&Dgr;α| of a thermal expansion coefficient difference &Dgr;α obtained by subtracting a thermal expansion coefficient αof the support substrate 11 from a thermal expansion coefficient αof the group III nitride film 13 is 2.2×10Kand under. A Young's modulus Eand a thickness tof the support substrate 11 and a Young's modulus Eand a thickness tof the group III nitride film 13, and the thermal expansion coefficient difference &Dgr;α satisfy a relation represented as t/t≥6E|&Dgr;α|/E.