Force-induced electrocatalytic abrasives in-situ electrochemical mechanical polishing 4H–SiC wafers

Aiming to overcome the long-standing trade-off between high material removal rate (MRR) and low surface damage in conventional chemical mechanical polishing (CMP) of 4H-SiC wafers, this study proposes an in-situ electrochemical mechanical polishing (in-situ ECMP) strategy using force-induced electrocatalytic abrasives (FIEA). The FIEA, composed of diamond, BaTiO 3 and binders, were fabricated via powder metallurgy, integrating diamond-based mechanical removal with BaTiO 3 -based piezoelectric catalytic functionality. Comparative polishing experiments were conducted under identical conditions, with traditional agglomerated diamond abrasives (AD) as the control. The results show that FIEA can stably generate a peak voltage of 2.25 V and a peak current of 210 nA under a polishing pressure of 31.03 kPa. Stress-induced piezoelectric polarization produces a localized interfacial potential difference when the positively polarized FIEA contacts 4H-SiC, thereby enhancing the equivalent anodic behavior of the 4H-SiC surface and inducing a transient equivalent electrochemical-like pathway at the abrasive/slurry/wafer interface. This significantly lowers the activation energy for surface oxidation and promotes Si-C bond rupture. Meanwhile, the piezocatalytic activity of FIEA accelerates the decomposition of H 2 O 2 and H 2 O, generating abundant hydroxyl radicals (·OH). X-ray photoelectron spectroscopy and UV-Vis analyses confirm that ·OH rapidly oxidizes the 4H-SiC surface to form a silica layer that is readily removed mechanically. As a result, the MRR achieved with FIEA reaches 105 nm/min, far exceeding the 28 nm/min obtained with AD, while the Sa is reduced to 4.5 nm with markedly fewer deep scratches. This work provides a promising abrasive design and mechanistic basis for high-efficiency, low-damage polishing of 4H-SiC wafers.