A study on polishing silicon wafers by hot melt adhesive polishing pads with abrasives coated in different ways

Polishing pads are precision polishing tools for flattening workpieces. The conventional two-dimensional aperture structured polishing pads not only wear out fast with the polishing process but also lead to poor surface quality when the polishing wastes fill the apertures and slow down the recycling of slurry. Conventional polishing pads are very costly to produce. This study attempts to develop a new type of hot melt adhesive (HMA) polishing pad that is flexible and has a three-dimensional interwoven, pore-rich structure. Larger apertures of the new pads are effective in both recycling of slurry and removing of polishing wastes. The experiment was designed based on the Taguchi method for polishing monocrystalline silicon with two types of pads. Type A involves coating the surface of the HMA pad with SiC abrasive by heat-pressure and Type B injects the SiC abrasive into the HMA when forming the surface of the pad. It was found that Type B pads, injected with abrasive of 1.2μm and a portion of 5 wt% had better effects with respect to surface roughness and within-wafer nonuniformity (WIWNU) than that of Type A (heat-pressure-coated with 1.2-μm abrasive) and conventional wool felt polishing pads.