Chemical etching of hot‐pressed p‐type polycrystalline SiC surfaces by HF/K2S2O8 solutions

Abstract

AbstractIn this work, an experimental study on the etching of p‐type hot‐pressed silicon carbide (SiC) was carried out in HF/K2S2O8 solutions. The SiC wafers used in this work were p‐type polycrystalline materials, supplied by Goodfellow, with an acceptor concentration of 2.31 × 1012 cm−3. The SiC substrate was a hot‐pressed material, the latter realized from a mixture of 1 part of SiO2 with 3 parts of C (carbon) ‘1SiO2 + 3C’ heated in an oven at 2500 °C. In order to facilitate the chemical etching of the SiC substrate, a thin aluminium film was deposited on the SiC substrate. The morphology of the etched surface was examined with varying K2S2O8 concentration. The surfaces of the etched samples were analysed using secondary ions mass spectrometry (SIMS), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT‐IR) and photoluminescence (PL). The surface morphology of the samples etched in HF/K2S2O8 is shown to depend on the solution composition. The investigation of the effect of the HF/K2S2O8 solution on SiC samples shows that as K2S2O8 concentration increases, the chemical etching reveals defects with random geometry. Finally, chemical etching of p‐type SiC induces a decrease in the PL intensity, which indicates clearly the defects on the polycrystalline SiC surface. In addition, the result is very interesting, as to date no chemical etching solution at low temperature (<100 °C) has been developed for SiC. Finally, we have proposed a dissolution mechanism of SiC in 2HF/1K2S2O8 solutions. Copyright © 2007 John Wiley & Sons, Ltd.