A Fully Self-Aligned SiC Trench MOSFET with 0.5 μm Channel Pitch

SiC power MOSFETs have made great progress since the first commercial devices were introduced in 2011, but they are still far from their theoretical limits of performance. At blocking voltages above 1200 V the specific on-resistance is limited by the drift region, but below 1200 V the resistance is dominated by the channel and the substrate, with smaller contributions from the source and JFET regions. Trench MOSFETs have smaller cell area than planar DMOSFETs, and are inherently more scalable. Both Rohm and Infineon devices have cell pitches of about 3 μm per active channel. In this paper we demonstrate a highly self-aligned fabrication process to realize deeply-scaled trench MOSFETs with a cell pitch of 0.5 μm per channel. Since the narrow gate trench is shaped like a letter “I”, we refer to these devices as “IMOSFETs”.