An Exploration of the Copper CMP Removal Mechanism

Abstract

Copper CMP is emerging as the next generation process technology enabling feature size reduction to .15μm and beyond[1]. We propose a copper removal mechanism in the context of a slurry consisting of an oxidizer and an abrasive. The body of evidence suggests that we are polishing in an oxidation complex rate limited regime. We observed low removal rate of copper in the absence of either oxidizer or abrasive, but rate was still dependent on CMP parameters and strongly tied to temperature. Any proposed mechanism must explain the observed dependence of rate on CMP aggressiveness and the role of each of the components. For the slurry used in this work we propose that an increase in temperature resulting from an increase in CMP intensity drives the kinetics of the oxidation reaction, and that the removal process can be classified as temperature-activated, abrasion assisted dissolution.