Piezocatalysis for Chemical–Mechanical Polishing of SiC: Dual Roles of t‐BaTiO3 as a Piezocatalyst and an Abrasive

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2024-05, Vol.20 (21), p.e2310117-n/a
• Main Authors: Hu, Tao, Feng, Jinxi, Yan, Wen, Tian, Shuanghong, Sun, Jingxiang, Liu, Xiaosheng, Wei, Di, Wang, Ziming, Yu, Yang, Lam, Jason Chun‐Ho, Liu, Shaorong, Wang, Zhong Lin, Xiong, Ya
• Format: Article
• Language: English
• Subjects: Activated sintering; Barium titanates; BaTiO3; Chemical-mechanical polishing; Clean energy; Density functional theory; Oxidation; Oxidizing agents; piezocatalytic‐CMP; Polishes; polishing; SiC; Silicon carbide; Silicon dioxide; Surface roughness
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202310117

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 BaTiO3 (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 SiO2, and subsequently, it acts as a usual abrasive to mechanically remove these SiO2. 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. Piezo‐chemical mechanical polishing (CMP) can efficiently polish the rough surface of 4H‐SiC to an atomic planarization surface. In this process, t‐BaTiO3 acts the dual role of a piezocatalyst and an abrasive, and no additional oxidant and energy are required. Thus, Piezo‐CMP is a green and effective polishing method.