Performance Improvement and Reliability Physics in SiC MOSFETs

Abstract

Significant improvement of channel mobility in SiC MOSFETs with high reliability and deep understanding of bipolar degradation in SiC are presented. By excluding oxidation of SiC while adopting H2 etching prior to oxide formation and interface nitridation, a low interface state density of 6×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> eV <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> near the conduction band edge was achieved in SiC(0001) MOS structures, which resulted in more than two-fold improvement of channel mobility. A physics-based model for stacking fault expansion upon excess carrier injection is proposed. The critical excess carrier density for stacking fault expansion was estimated to be (4–6)×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">14</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> at 300 K. A design guideline of a "recombination-enhancement layer", which prevents hole injection into the underlying substrate, is described.