High density plasma via hole etching in SiC

Throughwafer vias up to 100 mum deep were formed in 4H-SiC substrates by in ductively coupled plasma etching with SF6/O-2 at a controlled rate of simil ar to0.6 mum min(-1) and use of Al masks. Selectivities of > 50 for SiC ove r Al were achieved. Electrical (capacitance-voltage: current-voltage) and c hemical (Auger electron spectroscopy) analysis techniques showed that the e tching produced only minor changes in reverse breakdown voltage, Schottky b arrier height, and near surface stoichiometry of the SiC and had high selec tivity over common frontside metallization. The SiC etch rate was a strong function of the incident ion energy during plasma exposure. This process is attractive for power SiC transistors intended for high current, high tempe rature applications and also for SiC micromachining. (C) 2001 American Vacu um Society.