Patent ID: 9550268
Date: 2017-01-24
CPC Classifications: B24B

Claim:
1. A substrate holding apparatus for holding a substrate to be polished and pressing the substrate against a polishing pad, said substrate holding apparatus comprising: a top ring configured to hold the substrate and press the substrate against the polishing pad; a vertical movement mechanism configured to vertically move said top ring; a torque detector configured to detect a torque of said vertical movement mechanism when said top ring is being lowered or being lifted by said vertical movement mechanism; and a controller in which a torque of said vertical movement mechanism when said top ring is brought into contact with a surface of the polishing pad at the time of a pad search is preset as a torque limit value, said pad search being defined as a process in which said top ring is lowered and brought into contact with the surface of the polishing pad to determine a contact position between the substrate held by the top ring and the polishing pad, wherein said controller is configured to preset a reference value from a torque detected by said torque detector when said top ring is being lowered or being lifted by said vertical movement mechanism, wherein said controller is configured to calculate a torque correction amount from said reference value and a torque which is detected by said torque detector when said top ring is being lowered or being lifted by said vertical movement mechanism, after said reference value is preset, and wherein said controller is configured to correct said torque limit value by using said torque correction amount.