Endpoint detection by chemical reaction

摘要

Detection of the endpoint for removal of a target film overlying a stopping film by removing the target film with a process that selectively generates a chemical reaction product (for example, ammonia when polishing a wafer with a nitride film in a slurry containing KOH) with either the target or stopping film, and monitoring the level of chemical reaction product as the target film is removed. The reaction product is extracted as a gas from the slurry and monitored using a threshold photoionization mass spectrometer.