High-speed Etching of Gallium Nitride Substrate Using Hydrogen-Contained Atmospheric-Pressure Plasma

Atmospheric-pressure plasma etching of a gallium nitride (GaN) substrate using hydrogen radicals instead of chlorine radicals was investigated toward the backside thinning of GaN vertical power devices to reduce on-resistance. As a basic experiment, a pipe-shaped electrode was placed facing the GaN substrate to generate atmospheric-pressure plasma of a gas mixture of helium and hydrogen and high-speed etching of approximately 4 mu m min(-1) was achieved. Although many spherical Ga metal particles were observed on the surface after processing, the addition of oxygen gas was found to be able to suppress them.