Dependence of GaN removal rate of plasma chemical vaporization machining on mechanically introduced damage

A high-efficiency planarization method combining atmospheric-pressure plasma etching [plasma chemical vaporization machining (PCVM)] and mechanical polishing is proposed. The convex part of a substrate surface, considered to be affected by mechanical action, is removed preferentially by PCVM. However, it is not evident whether the PCVM removal rate of the damaged layer of a gallium nitride (GaN) substrate increases. In this study, the dependence of removal rate on removal depth is investigated using a GaN substrate with a damaged layer. As a result, the removal rate of the damaged layer is observed to be three or four times greater than that of deep undamaged layers.