Environment-friendly chemical mechanical polishing using NaHCO3-activated H2O2 slurry for highly efficient finishing of 4H-SiC (0001) surface

Abstract

Silicon carbide (SiC) is recognized as one of the most promising and widely used semiconductor materials, but the current chemical mechanical polishing (CMP) process for SiC is inefficient and polluting. There is badly in need of developing an efficient and environmentally friendly CMP polishing solution for SiC. This paper proposes the use of a bicarbonate-activated hydrogen peroxide (BAP) system in SiC CMP to address the inefficiency and environmental concerns. The BAP system aims to develop an economical, environmentally friendly, efficient, and sustainable SiC CMP solution. Comparative tests were conducted to validate the material removal rate (MRR), surface roughness (Sa), and morphology of 4H-SiC samples after CMP processing. The experimental results show that the introduction of NaHCO3 induces the generation of different reactive oxygen radicals (·CO3−, ·O2−, 1O2) when combined with hydrogen peroxide (H2O2). This enhancement significantly improves the oxidation performance of the polishing solution. The average MRR after a 2-hour CMP process is measured at 220 ± 5 nm/h, which represents a remarkable 450 % increase in material removal efficiency compared to using pure H2O2 slurry. Furthermore, the surface roughness (Sa) after polishing is measured at only 0.283 ± 0.016 nm, indicating a smooth surface without noticeable scratches.