Slurry-free atomic-scale planarization of Si(100) via solid-base-catalyzed etching in pure water

We have developed a new Si wafer polishing method that achieves ultra-smooth surfaces, surpassing those of conventionally final polished wafers. This method employs a solid-base catalyst as the polishing pad and uses only pure water—without any abrasive particles or chemical additives—resulting in a significant reduction in environmental impact. The configuration of the polishing machine is identical to that of conventional systems, except for the pad material. The removal rate is approximately 30 nm/min, which is comparable to that of existing methods. We have confirmed that the polishing mechanism is governed by a catalyzed alkali etching, which proceeds preferentially at surface protrusions due to the selective supply of OH - ions captured on the solid-base catalyst.