Super junction 4H-SiC trench MOSFET for enhancing reverse recovery performance

In the report, aimed the problem that in the high-voltage and high-frequency applications, because of the increase of the pn junction area of the traditional trench MOSFET structures (CT-UMOS), 4H-SiC trench MOSFET structure affects the reverse recovery performance, a novel super junction 4H-SiC trench MOSFET structure (NSJ-UMOS) was designed. The structure introduced an NSJ super junction below the source, an SSJ structure composed of high concentration n+, low concentration n1+, and p1+regions was used to optimize the electric field distribution between the internal and gate oxide layers. TCAD simulation test was performed to verify the significant improvement of the performance of NSJ-UMOS. The results indicated that the reverse recovery time of NSJ-UMOS is shortened from 1.01 μs to 0.02 μs, the breakdown voltage is increased to 4030 V, the gate drain capacitance is reduced from 33.6 pF to 0.402 pF, the specific on resistance is reduced from 54.49 mΩ·cm² to 8.26 mΩ·cm², and the switching power consumption is reduced by 39.51%. The above improvements improved significantly the forward conduction performance, reverse recovery performance, and third quadrant performance of the device, which make it more advantageous in the high-voltage, high reliability, and high-frequency applications.