Mechanical Abrasion by Bi-Layered Pad Micro-Asperity in Chemical Mechanical Polishing

Abstract

Pad asperities in chemical-mechanical polishing (CMP) provide necessary forces for mechanical abrasion, yet they are lack of precision in design and manufacturing. In this study, we investigate the polishing behaviour in CMP at the asperity contact scale. Contact mechanics model predicts that compliant and soft asperities or rigid and hard asperities may achieve either large contact area or high indentation depth respectively, whereas bi-layered asperities can enable both. We realize the well-defined pad micro-asperity fabrication using thermal reflow and micro-replica moldingtechniques, including the new bi-layered asperity design, and experimentally compare their polishing behaviours using a customized CMP test setup.