Reliability Comparison of Commercial Planar and Trench 4H-SiC Power MOSFETs

Abstract

The gate oxide reliability, bias temperature insta-bility (BTI), and short-circuit capability for commercial SiC power MOSFETs with planar and trench structures are evaluated and compared in this work. The asymmetric trench MOSFET has the thickest gate oxide among the tested devices, which provides the highest extrapolated gate oxide lifetime from the constant-voltage time-dependent dielectric breakdown (TDDB) measurements. Also, the asymmetric trench structure shows the longest short-circuit withstand time (SCWT) benefiting from the adjacent P+ regions. However, the asymmetric trench MOSFETs show a high threshold voltage shift during the BTI measurements under AC stress, indicating more at or near SiC/SiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> interface defects. The double trench MOSFETs also show better short-circuit ruggedness, but no obvious advantages in the TDDB measurements and BTI results.