Patent ID: 8338299
Filing Date: 2012-12-25
Classification: C09G,C30B,H01L

Abstract:
1. A method of processing a surface of a group III nitride crystal, the method comprising steps of: polishing a surf ace of a group III nitride crystal with a polishing slurry containing abrasive grains; and thereafter polishing said surface of said group III nitride crystal with a polishing liquid that does not contain abrasive grains at least once, wherein: each step of polishing with said polishing liquid employs one of a basic polishing liquid and an acidic polishing liquid as said polishing liquid; and said basic polishing liquid contains at least one type selected from the group consisting of a base having only at least any of C, O, H and N as a constituent element, a salt thereof and an oxidizer having only at least any of C, O, H and N as a constituent element and has a pH of at least 8.5 and at most 14, and if said pH is represented by a value x and said basic polishing liquid has an oxidation reduction potential represented by a value y represented in mV, said values x and y satisfy the following expression: said acidic polishing liquid contains at least one type selected from the group consisting of an acid having only at least any of C, O, H and N as a constituent element, a salt thereof and an oxidizer having only at least any of C, O, H and N as a constituent element and has a pH of at least 1.5 and at most 6, and if said pH is represented by a value x and said acidic polishing liquid has an oxidation reduction potential represented by a value y represented in mV, said values x and y satisfy the following expression: