A proven technology has been developed for monitoring and controlling the CMP processes involving a stop at a layer which contains nitride. This technology is based on the fact that a measurable amount of ammonia (NH{sub}3) will be generated during the nitride polishing. The detection of ammonia is accomplished by converting ammonia to nitrogen monoxide (NO) catalytically, then reacting the NO with ozone (O{sub}3) to form excited state nitrogen dioxide (NO{sub}2) followed by detecting its light emission. The endpoint detection system is designed to analyze and to measure these very small changes of ammonia concentration within the slurry with high velocity (～1 sec) and accuracy (ppb). The system is already approved for BPSG and STI CMP processes on different polisher types -Ebara and SpeedFam-IPEC (Westech and Auriga C).
展开▼
