Nitride semiconductor device and fabrication method thereof, and method for forming nitride semiconductor substrate

摘要

A nitride semiconductor device comprising a substrate ( 101 ) having trenches ( 102 b) each formed of a cavity and peaks ( 102 a) formed from a group III nitride on the surface thereof; a nitride semiconductor layer ( 106 ) formed on the substrate ( 101 ); and a nitride semiconductor multilayered structure that is formed on the nitride semiconductor layer ( 106 ) and has an active layer, wherein the lattice constant of the substrate ( 101 ) is different from that of the group III nitride substance ( 102 a), the substrate ( 101 ) has a mask ( 104 a) formed from a dielectric ( 104 ), the mask ( 104 a) is formed only on the side surfaces of the peaks ( 102 a), the upper surfaces of the peaks ( 102 a) are exposed and the substrate ( 101 ) is exposed in the trenches ( 102 b), a height L 1 of the mask ( 104 a) is not less than 50 nm and not more than 5000 nm, a width L 2 of the trench ( 102 b) is not less than 5000 nm and not more than 50000 nm, and an aspect ratio L 1 /L 2 of the trenches ( 102 b) is not less than 0.001 and not more than 1.0. This structure enhances the reliability of the nitride semiconductor devices.