Prediction of polishing pressure distribution in CMP process with airbag type wafer carrier

This paper presents a CMP process analysis considering an airbag type wafer carrier, which is used in semiconductor devices manufacturing. In the CMP process, a wafer is compressed against the polishing pad inside the wafer carrier, which consists of the retainer ring and the membrane film. Structural analysis model is developed to estimate contact pressure distribution over the wafer surface considering the airbag compression behaviour. The polishing experiment without wafer rotation indicated a unique pressure variation around the trailing edge of the wafer. The developed analysis estimated the same phenomena accurately and clarified the mechanism deteriorating the polishing pressure uniformity.