Patent ID: 6991514

Claim:
An optical closed-loop control system for use with a chemical mechanical polishing (CMP) apparatus for polishing a semiconductor wafer, said CMP apparatus having a platen, a polishing pad coupleable with a top surface of said platen and a wafer carrier, said system comprising: a plurality of optical probes impacting a corresponding probe window and rigidly mountable through said platen, said probe window positioned within said polishing pad; a flash lamp configured to provide light to each of said plurality of said optical probes and minimize an exposure time of said light onto said semiconductor wafer; a spectrograph configured to spatially image light received by each of said plurality of said optical probes to a common charge-coupled device (CCD) and produce real-time spectral reflectometry data therefrom; and a control subsystem configured to analyze said real-time spectral reflectometry data and determine at least one wafer state parameter therefrom, and cause polishing to be adjusted based upon said at least one wafer state parameter.