Determination of optimum structure of 4H-SiC Trench MOSFET

A critical issue for the 4H-SiC UMOSFET is a shielding of the gate oxide at the bottom of the trench gate from the high electric field during the blocking state. This study develops the UMOSFET structure with low specific on-resistance and low electric field in the gate oxide by the two-dimensional numerical device simulation. The gate oxide field is successfully decreased without the degradation of the on-resistance by the structure with the buried p-base region. Furthermore, two-zone Superjunction structure that applies the buried p-base region is also proposed for the 3300 V device.