Patent ID: 9233449
Filing Date: 2016-01-12
CPC Classification: B24B

Claim Text:
1. A polishing method comprising: preparing a Ga element-containing compound semiconductor substrate, whose surface has raised portions and recessed portions; immersing the substrate in a processing solution comprising a buffer solution containing Ga ions, a concentration of the Ga ions being in a range of 10 ppm to 100 ppm, and the buffer solution having a pH in a range of 6 to 8; irradiating the surface of the substrate with light or applying a bias potential to the substrate, or applying a bias potential to the substrate while irradiating the surface of the substrate with light, thereby forming Ga oxide on the surface of the substrate in the processing solution; and rotating the substrate and a polishing tool with respect to each other to selectively polish and remove the Ga oxide formed on the raised portions of the surface of the substrate, wherein the processing solution contains oxygen dissolved therein, and wherein the processing solution does not comprise nitrogen dissolved from any Ga element-containing compound semiconductor substrate.