A method and system for detecting a planarization endpoint of a semiconductor wafer planarization operation, which includes monitoring a motor current for at least one of a platen motor, a carousel motor and a head motor, performing a Fourier transform of the monitored current to identify periodic oscillations...http://www.google.de/patents/US6293845?utm_source=gb-gplus-sharePatent US6293845 - System and method for end-point detection in a multi-head CMP tool using real-time monitoring of motor current
