Investigation on defect control for final chemical mechanical polishing of aluminum alloy

Abstract

In acid final chemical mechanical polishing (CMP) of aluminum alloy, the addition of a small amount of nitric acid (HNO₃) is proved to be the effective measure for reducing the orange peel defect due to the protective film produced by HNO₃ on aluminum alloy; however, it makes point defects worse. The effect of hydrolyzed polymaleic anhydride (HPMA) on point defects is investigated. HPMA adsorbs on the surface of aluminum alloy first, and the composite film formed by both HPMA and HNO₃ is proved to be efficient for controlling both the orange peel and point defects. When the aluminum alloy is polished by the acid original slurry with 0.7 wt% HNO₃ and 0.1 wt% HPMA, the roughness of the aluminum alloy surface is low to 0.678 nm.