Patent ID: 8454407

Claim:
A polishing method of polishing a substrate as an object to be polished by pressing the substrate against a polishing surface on a rotating polishing table, said polishing method comprising: scanning a surface, being polished, of the substrate by an eddy current sensor provided in the polishing table while the polishing table is rotated, during polishing of the substrate; and monitoring an output of the eddy current sensor obtained by scanning the surface, being polished, of the substrate and detecting damage of the substrate from a change in the output of the eddy current sensor, wherein an effective substrate width is determined from the output of the eddy current sensor in an N-th revolution, N being an integer not less than 1, of the polishing table, a substrate width is determined from the output of the eddy current sensor after the N-th revolution of the polishing table, and when the determined substrate width is narrower than the effective substrate width, it is judged that the damage of the substrate occurs.