Study on Reactive Species in Catalyst-Referred Etching of 4H-SiC using Platinum and Hydrofluoric Acid

In this study, we developed a novel abrasive-free polishing method called the catalyst-referred etching (CARE). CARE can chemically remove SiC using an etching agent activated by a catalyst. Platinum and hydrofluoric (HF) acid are used for the planarization of SiC substrates as a catalyst and etchant, respectively. CARE can produce an atomically flat surface of 4H-SiC (0001) with a root-mean-square roughness <0.1 nm, regardless of the cut-off angle. However, the mechanism of CARE has not yet been clarified. In this study, to clarify the mechanism, KF and NH4F are added to the etchant. An investigation revealed that the removal rate is proportional to [HF] x ([F-] + [HF2-]), and it is shown that both the HF molecule and fluorine ions (F- and HF2-) are reactive species of the CARE process.