Design and Demonstration of a Novel SiC Trench MOSFET with Periodically Grounded P Shield Island Based on Secondary Epitaxy Process

This paper proposes a novel silicon carbide (SiC) trench MOSFET with periodically grounded P shield islands (SiC PSI-MOS) based on a secondary epitaxy process. The proposed SiC PSI-MOS structure utilizes a patterned P shield island formed through etching, ion implantation, and secondary epitaxy, enabling deeper shielding with lower energy implantation while maintaining gate oxide reliability. In the blocking state, the P shield region and P shield island effectively shield the drain potential, reducing the gate oxide electric field to a safe level (1.07 MV/cm at 1200 V). In the on-state, the drift between the P shield and the island creates additional current paths, lowering specific on-resistance (4.9 mΩ·cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at a 7.5 μm cell pitch). In addition, a feasible fabrication process is demonstrated, with experimental results confirming the device’s output and transfer characteristics. The SiC PSI-MOS offers an optimized trade-off between gate oxide reliability and conduction performance.