Polishing of ILD and STI by the LHA pad

Abstract

This paper examines whether a polishing pad with abrasive grain can be adapted for oxide CMP (ILD CMP and STI CMP), which is currently performed by free abrasive polishing. Using the Loosely Held Abrasive (LHA) pad that is effective in the polishing of silicon wafers, silicon oxide and silicon nitride films are polished, and the polishing selectivity and performance are investigated. In the CMP of a silicon oxide film, it is revealed that the removal rate using the combination of the LHA pad and water is 1.6 times more than that using slurry and is compatible in the almost equivalent non-uniformity within a wafer. In free abrasive polishing, the polishing selectivity of a silicon oxide film is 1.4 times that of a silicon nitride film; however, in the case of the LHA pad, it was revealed that the polishing selectivity is 10 times or more. The LHA pad, which is a polishing pad with abrasive grain, can be adapted for ILD CMP and STI CMP, and the polishing selectivity and performance is better than free abrasive polishing.