Polishing of diamond, SiC, GaN based on the oxidation modification of hydroxyl radical: Status, challenges and strategies

As the wide band-gap semiconductor materials, single crystal diamond, SiC, GaN are the key in semiconductor fields. Due to the high hardness, high brittleness and strong chemical inertness, they are the typical difficult to machine materials. To solve the problem of high-efficiency and ultra-precision polishing, based on the strong oxidation potential that hydroxyl radical (•OH) can oxidize diamond, SiC and GaN, the main formation methods of •OH, the polishing mechanisms assisted by •OH and the polishing processes were systematically analyzed. Through comparative analysis, the advantages of heterogeneous Fenton reaction and its applicability in engineering application were verified. The beneficial effects of physical fields cooperated with heterogeneous Fenton reaction on increasing the yield of •OH were demonstrated. The basic theoretical problems being solved urgently were pointed out, for example, the oxidation mechanisms of •OH and the optimization mechanisms of polishing performance assisted by •OH. Finally, the physical and chemical strengthening methods of Fenton oxidation efficiency were emphatically analyzed. Introducing these strengthening methods into the polishing processes of diamond, SiC and GaN to develop new technologies from the perspectives of polishing slurry, polishing pad and polishing process, which can provide rich methods and strategies for the high-efficiency and ultra-precision polishing.