A robust and area-efficient guard ring edge termination technique for 4H-SiC power MOSFETs. (September 2017) - Deng, Xiaochuan
Abstract: A robust and area efficient adjusted multi-section guard rings (AMS) edge termination structure is employed to a 4H-SiC power MOSFET device rated at 1.7 kV and fabricated without extra process steps or masks in this paper. The lightly doped p-type guard ring with adjusted multi-section spacing, which is similar with varied lateral doping technology widely used in silicon edge termination, creates a smoother and more uniform surface electric field distribution across all rings, resulting in a higher reverse blocking voltage with minimal edge termination area. The fabricated AMS-MOSFET devices with an active area of 2.5 mm 2 have reverse blocking voltage up to 2.5 kV at room temperature. Compared to the conventional SiC MOSFETs with the uniform ring spacing, the AMS-MOSFET with the same edge termination area shows more than a 25% increase in the reverse blocking voltage. Furthermore, high-temperature reverse bias stress test is performed to verify junction and termination robustness of the AMS-MOSFET device. A small variation in the reverse blocking voltage and drain-source leakage current are achieved under 168 h high-temperature reverse bias stress with the drain bias of 1360 V at ambient temperature of 175 °C, which suggests an expected robustness in high power application for the fabricated SiC MOSFET with the AMS structure.