Hybrid assisted polishing technique for 4H-SiC wafers using parallel plate dielectric barrier discharge plasma and mechanical polishing

To achieve sustainable and efficient production of 4H-SiC wafers, this study proposes a two-step plasma-assisted polishing method, which combines the parallel plate dielectric barrier discharge (PP-DBD) plasma irradiation with mechanical polishing (MP) using soft abrasives: (1) parallel-plate dielectric barrier discharge (PP-DBD) plasma irradiation to soften the wafer surface, followed by, (2) soft abrasives MP to remove the modified layer and achieve high surface quality. Key processing parameters—electrode spacing, applied voltage, and irradiation duration—were systematically optimised to form a uniform modified layer approximately 35 nm thick. The modified surfaces were characterised using transmission electron microscopy (TEM) and ellipsometry. The process achieved a material removal rate (MRR) of 220 nm/h, reducing the polishing time required to reach the target surface roughness from 300 min to 15 min compared with soft abrasives MP. This two-step, chemical-free approach significantly improves both polishing efficiency and surface quality, offering a scalable and environmentally sustainable solution for ultra-precision finishing of 4H-SiC wafers.