A novel surface polishing method and its fundamental performance in ultra-fine polishing of wafer

Magnetorheological finishing, considered as a promising polishing technique that can finish a nano-level smooth surface and free of surface or subsurface damage, has been widely utilized in ultra-smooth polishing of hard-to-machine materials. However, there are still several practical weaknesses in magnetorheological finishing (MRF) applied for wafer surface polishing. In this study, a new method using MRF effect was proposed for wafer polishing. Concretely, porous foam was used as a storage carrier of MR slurry, and thus, MR slurry can be bounded in porous foam in the finishing process (cluster MR-porous foam polishing, CMRPP). In this paper, an experimental rig was constructed to achieve CMRPP mechanism, the processing principle and material removal process in CMRPP were analyzed, and CMRPP experiments were conducted to investigate the effects of porous foam on surface polishing. The results indicate the following: (1) The polishing forces in CMRPP were increased compared to that of a cluster MR polishing without porous foam (CMRP), and CMRPP can get a greater shear force than of CMRP at a same normal force; (2) CMRPP can well hinder the solid-liquid separation and sustain the stability of the slurry performance; (3) CMRPP achieved a higher volumetric removal rate than that of CMRP and improving of material removal efficiency; (4) CMRPP can effectively achieve a nano-level smooth surface compared to that of CMRP.