Investigations of SiC VDMOSFET with Floating Island Structure Based on TCAD

Abstract

Using TCAD simulations, the silicon carbide metal-oxide-semiconductor field-effect transistor with p-type floating islands (SiC FLIMOSFET) is systematically investigated in this paper. The doping concentration (N _FLI ), length (L), and position (D1) of floating islands are optimized according to breakdown voltage (BV), electric field distribution, and on-resistance. The results show that NFLI = 1 × 10 ¹⁷ cm ^-3 , L = 2.5 μm, and D1 = 9.0 μm are superior values for FLI structure considering tradeoff between BV and on-resistance. With the same BV capacity, the on-resistance of SiC FLIMOSFET is decrease by 32% comparing to the conventional SiC VDMOSFET. Besides, the dynamic property shows 16.5% reduction of FoM R _{on} cdot Q _GD in the SiC FLIMOSFET. Significantly, comparing to the conventional structure, the electro-thermal simulation indicates that the SiC FLIMOSFET has a higher robustness under short-circuit condition owing to the reduction of thermal stress in SiC/SiO ₂ interface. All the results show that the SiC FLIMOSFET has a good potential in SiC power device.