Real-time detection of resist strip failure at metal etch process equipment

Metal etch process is to form the electrical metal lines of device on a wafer. DPS of AMAT, the one of metal etch process equipments, is assembled chambers for metal etch process and resist strip process. The wafer proceeds metal etch process and resist strip process continuously. If resist were not removed clearly in the strip process chamber, its ash induces serious defect to metal lines. Despite such a failure has been randomly occurred in resist strip chamber, real-time detection of it was impossible under interlock system by using classical SPC. This paper shows how it is possible to detect resist strip failure in real-time by modeling. As a result, wafer loss by resist ash could be decreased effectively in the metal etch process.