Patent ID: 6878629
Filing Date: 2005-04-12
Classification: B24B,H01L

Abstract:
1. A method of detecting endpoint, comprising the steps of: a. polishing a surface of a semiconductor wafer using an acidic chemical mechanical polishing (CMP) slurry that is absent a presence of ammonia gas in a polishing portion of CMP apparatus, the semiconductor having a portion below the surface; b. collecting at least some of said acidic CMP slurry during the polishing; c. interacting said collected acidic CMP slurry with a pH modifier such that the pH of the slurry is at least neutral and such that, after said interacting step, ammonia gas is present in said interacted CMP slurry; d. measuring the amount of ammonia gas present; e. discontinuing the polishing in step a when the amount of measured ammonia gas in step d at least reaches a predetermined value.