Removal of TaN/Ta Barrier with Variable Selectivity to Copper and TEOS

Abstract

Highly selective 2^nd step copper slurries developed by Rodel have efficient barrier (TaN) polishing rates at extremely low down force (1000 Å/min at one psi, and 2000 Å/min at 3 psi). Removal rates of dielectrics (TEOS or low k CDO) can be independently adjusted from zero to nearly any designed value and copper removal rates can be independently controlled from 20 to 500 Å /min, while maintaining the high barrier removal rates. In addition, zero loss of low-k dielectric capping layers has been demonstrated, and zero loss of high metal density (90%) domain of pattern wafers with 30 seconds overpolishing has been demonstrated. Experiments also show that the high selectivity is a true CMP effect and not due to static etching.