Patent ID: 7258595

Claim:
A polishing apparatus comprising: a polishing table having a polishing surface; a workpiece holding mechanism for holding a workpiece to be polished, such that when the workpiece is held by said workpiece holding mechanism and pressed against said polishing surface the workpiece is polished through motion of the workpiece relative to said polishing surface; and an eddy-current type sensor, having a sensor coil, in one location in a vicinity of a workpiece holding section of said workpiece holding mechanism, said eddy-current type sensor for measuring an electrical resistance and an electrical reactance between said eddy-current type sensor and a surface of said polishing table to detect escaping of the workpiece when a value of the electrical resistance or electrical reactance between said eddy-current type sensor and the surface of said polishing table, as measured by said eddy-current type sensor, is greater than a predetermined value.