Study of crack generation process in scratching of gallium nitride

Single-crystal GaN has many excellent features, including high thermal conductivity, heat dissipation, possibility of operation at high temperature, high speed of electron saturation, and high dielectric breakdown voltage. Therefore, it is expected to be utilized for power devices with low power loss. GaN has a hardness of 1800 – 2000 Hv and is brittle, so it is very difficult to process. This research was performed to clarify the crack generation mechanism in the GaN semiconductor grinding process. To investigate the process of crack generation during single grinding, scratching experiments were conducted on the Ga polar plane of a GaN substrate using a single-crystal diamond indenter. The scratching results indicated that it is necessary to set the depth of cut of the tool to ≤ 180 nm to grind in the ductile state.