Abstract: There are provided a processing method for a wide-bandgap semiconductor substrate and an apparatus therefor that use no abrasives or no abrasive grains, or no solution having a large environmental burden at all, can process a single crystal, which is SiC, GaN, AlGaN, or AlN, at a variety of processing speed, can obtain a surface of higher quality than the quality of a surface finished by CMP, and also have an excellent compatibility with a clean room. A catalytic substance having a function of promoting the direct hydrolysis of a work piece (5) or promoting the hydrolysis of an oxide film on the surface of the work piece is used as a processing reference plane (3). In the presence of water (1), the work piece is brought into contact with or extremely close to the processing reference plane at a predetermined pressure.

Abstract: A substrate polishing apparatus includes a retainer for holding a substrate and substrate rotating device that spins the retainer around a first rotational axis perpendicular to a to-be-polished surface of the substrate. A platen includes an abrasive pad disposed opposite of the to-be-polished surface of the substrate. A platen rotating device spins the platen around a second rotational axis perpendicular to the abrasive pad. A liquid storage chamber includes a wall portion surrounding the outer periphery of the substrate. One end of the wall portion is positionable in a liquid-tight manner with the abrasive pad to define a liquid storage space for retaining a polishing liquid around the outer periphery of the substrate.