| 摘要 |
Polishing a nitride semiconductor monocrystalline wafer leaves it with a process-transformed layer. The process-transformed layer has to be etched to be removed. The chemical inertness of nitride semiconductor materials has, however, precluded suitable etching. Although potassium hydroxide, for example, or sulfuric acid have been proposed as GaN etchants, their ability to corrosively remove material from the Ga face is weak. Dry etching utilizing a halogen plasma is carried out in order to remove the process-transformed layer. The Ga face can be etched off with the halogen plasma. Nevertheless, owing to the dry etching, a problem arises again—surface contamination due to metal particles. To address the problem, wet etching with, as the etchant, solutions such as HF+H2O2, H2SO4+H2O2, HCl+H2O2, or HNO3, which are nonselective for Ga/N faces, have metal etching capability, and have an oxidation-reduction potential of 1.2 V or more, is performed.
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