Study on the photoelectrochemical etching process of semiconducting 6H-SiC wafer

Several dry etching methods which are commonly used for the fabrication of SiC devices are known to result in ion-induced damage on the etched surface, which is highly undesirable for the high frequency and high power device operation. In this paper we report on photoelectrochemical etching process of semiconducting 6H-SiC wafer. The etching process consists of illumination of UV in HF-based electrolyte, thermal oxidation, and HF dipping. An etching rate of 760 Åmin^-1 was obtained using a dilute HF(1.4 wt.% in H₂O) electrolyte with the etching potential of 3.5 V. The etching rate was found out to increase with the bias voltage. Double-step oxidation process was found out to be useful for the decrease of the surface roughness. It was shown that the addition of H₂O₂ into the HF solution improves the etching rate of the SiC surface. The PEC etching resulted in a highly anisotropic etching characteristics and shown to have a potential for the fabrication of SiC devices.