Two-Step Chemical Mechanical Polishing of Stainless Steel

Abstract

Stainless steel with high surface quality is required in many industries and chemical mechanical polishing can achieve both local and global planarization of the substrate surface. However, it is difficult to realize both high material removal rate and high surface quality by a single step polishing. In this regard, a two-step polishing process, coarse polishing with α-Al2O3 abrasives first and then fine polishing with silica abrasives, was proposed to solve the trade-off between material removal and surface quality. The effects of pH (1 ∼ 12) and H2O2 (0 ∼ 0.5 wt%) on the polishing of 304 stainless steel disk (area ∼ 6.7 cm2) were systematically studied and CMP mechanism of stainless steel was discussed. The results indicated that, at pH 4, with the addition of 0.01 wt% H2O2, the surface roughness of stainless steel was successfully reduced from 0.702 μm to 44.6 nm (the first step using α-Al2O3 abrasives) and 1.61 nm (the second step using silica abrasives). Finally, an ultra-smooth surface was obtained with decent material removal rate.