Endpoint detection system for wafer polishing

Abstract

An wafer polishing pad assembly for use in CMP includes an optical sensor for sensing reflectivity of the wafer during polishing, and produces a corresponding signal, and transmits the signal from the rotating pad to a stationary portion of the assembly. The signal is transmitting off the pad through non-contact couplings such inductive coupling or optical couplings after being converted into signal formats enabling non-contact transmission.

1 . A polishing pad assembly for polishing a wafer surface and collecting and transmitting data relating to the condition of the wafer surface, said polishing pad assembly comprising:
 a polishing pad;   means for directing light at the wafer surface, said means disposed within the polishing pad;   means for detecting light reflected from the wafer surface and creating an electrical signal corresponding to the light reflected, said means for detecting light disposed within the polishing pad;   means for processing the electrical signal corresponding to the light reflected and producing a corresponding processed signal, said means for processing the electrical signal disposed within the pad; and   a transmitter for transmitting the processed signal, said transmitter operably coupled to the means for processing the electrical signal.