Physical Mechanisms Limiting the Channel Mobility in 4H-SiC MOSFETs

SiC lateral MOSFETs were fabricated on an epitaxially-grown p-well on an n-type 4HSiC substrate. Source and drain regions were implanted with Nitrogen, and a body contact region was co-implanted with Aluminum and Carbon. Wafers were capped with graphite and implants were activated for 30 minutes at 1650°C. After sacrificial oxidation, the 80 nm gate oxide was grown at 1250°C in N20 followed by NO oxidation at 1175°C. A liftoff process was used to deposit Nickel for Ohmic contacts to n-type and p-type regions. The Molybdenum gate metal was deposited and patterned and then the Ohmic contacts were annealed at 1050°C for 3 minutes. Annular long-channel MOSFETs (Lch=100 pm) and MOS-gated Hall structures were fabricated and characterized as a function of temperature.