Accelerated C-face polishing of silicon carbide by alkaline polishing slurries with Fe3O4 catalysts

Abstract

As a third-generation semiconductor material, Silicon carbide (SiC) excels in extraordinary physical and chemical properties, which makes, in turn, it hard to process. The strong oxidizing species·OH produced by the Fenton reaction has been effectively applied in the chemical mechanical polishing (CMP) of single-crystal SiC. In order to expand the applicable pH range of Fenton reaction, magnetic recoverable Fe3O4 nanocatalysts were prepared in this paper, and the Fenton system was successfully applied to SiC polishing in alkaline silica slurry, which significantly improved the material removal rate (MRR). UV–vis spectroscopy curves prove that in a H2O2 containing slurry, more·OH radicals were produced at pH 2.5 than that at pH 9.0 during Fe3O4 catalyst-assisted polishing, which is consistent with conventional wisdom about Fenton Reaction. Surprisingly, MRR of SiC wafer up to 632 nm/h was achieved at pH 9.0 instead of 2.5 using the same slurry. A detailed hypothesis is presented to elucidate the material removal mechanism of the Fenton reaction system on SiC polishing.