Patent ID: 7452814

Claim:
A method of polishing a GaN substrate of which surface to be polished has Ga portions and N portions alternatively arranged, comprising: a first polishing step of polishing the GaN substrate held by a polishing jig, using a first platen made of a material including tin and a polishing solution, while supplying the polishing solution containing first abrasives and a first lubricant, onto the first platen; a second polishing step of polishing the GaN substrate held by the polishing jig, using a second platen, made of a material including tin, in which second abrasives are buried, while supplying a second lubricant onto the second platen in which the second abrasives are buried, after the first polishing step; and in at least one of the first and second polishing steps, rotating the first or second platen and the polishing jig in the same direction.