Piezocatalysis for Chemical–Mechanical Polishing of SiC: Dual Roles of t‐BaTiO 3 as a Piezocatalyst and an Abrasive

Chemical mechanical polishing (CMP) offers a promising pathway to smooth third‐generation semiconductors. However, it is still a challenge to reduce the use of additional oxidants or/and energy in current CMP processes. Here, a new and green atomically smoothing method: Piezocatalytic‐CMP (Piezo‐CMP) is reported. Investigation shows that the Piezo‐CMP based on tetragonal BaTiO 3 ( t ‐BT) can polish the rough surface of a reaction sintering SiC (RS‐SiC) to the ultra‐smooth surface with an average surface roughness (Ra) of 0.45 nm and the rough surface of a single‐crystal 4H‐SiC to the atomic planarization Si and C surfaces with Ra of 0.120 and 0.157 nm, respectively. In these processes, t ‐BT plays a dual role of piezocatalyst and abrasive. That is, it piezo‐catalytically generates in‐situ active oxygen species to selectively oxidize protruding sites of SiC surface, yielding soft SiO 2 , and subsequently, it acts as a usual abrasive to mechanically remove these SiO 2 . This mechanism is further confirmed by density functional theory (DFT) calculation and molecular simulation. In this process, piezocatalytic oxidation is driven only by the original pressure and friction force of a conventional polishing process, thus, the piezo‐CMP process do not require any additional oxidant and energy, being a green and effective polishing method.