Two-Step Chemical Mechanical Polishing of Stainless Steel

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 alpha-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 similar to 12) and H2O2 (0 similar to 0.5 wt%) on the polishing of 304 stainless steel disk (area similar to 6.7 cm(2)) 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 mu m to 44.6 nm (the first step using alpha-Al2O3 abrasives) and 1.61 nm (the second step using silica abrasives). Finally, an ultra-smooth surface was obtained with decent material removal rate.