Method and apparatus of the scene end point detection and process monitoring for chemical mechanical polishing

A chemical mechanical polishing apparatus has a polishing pad (30), a carrier (70) to hold a substrate (10) against a first side of the polishing surface, and a motor coupled to at least one of the polishing pad (30) and carrier head (70) for generating relative motion therebetween. An eddy current monitoring system (40) is positioned to generate an alternating magnetic field in proximity to the substrate (10), an optical monitoring system (140) generates a light beam and detects reflections of the light beam from the substrate (10), and a controller (90) receives signals from the eddy current monitoring system (40) and the optical monitoring system (140).