Cu-CMP for dual damascene technology: Prestonian vs. non-prestonian regimes of Cu removal

Abstract

Dual damascene Cu (Cu2D) is increasingly becoming the process of choice for IC technology. The Cu2D manufacturing sequence includes multiple use of CMP for both dielectric planarization and for shaping Cu interconnects, thereby making CMP an enabling operation. The performance of Cu-CMP has been observed to be slurry-dependent; while slurries typically exhibit the expected Prestonian behavior, i.e., a linear dependence of removal rate on pressure and speed, some slurries exhibit deviation from this linear behavior, especially at higher pressures. Such slurries are usually referred to as pressure-sensitive slurries. This paper analyzes a general scheme for Cu removal mechanism and explores the possible reasons behind the non-Prestonian anomaly.