Optimization of junction termination extension for ultrahigh voltage 4H-SiC planar power devices

Numerical simulations on the optimization of junction termination extension (JTE) have been performed. Various termination techniques have been applied and simulated in this paper, such as single-zone JTE (S-JTE), multi-zone JTE (M-JTE), and space-modulated JTE (SM-JTE). A completely novel and efficient method is demonstrated in this paper to determine total length of SM-JTE, and it is verified through simulation results. The simulation results show that the SM-JTE could provide a protection efficiency (defined in Section 2) of 95.2%, which is much higher than that of M-JTE (82.4%) and S-JTE (64.7%). Based on the fabricated MOSFETs, the interface charge density is extracted and the approximate range of charge density has been determined. The influences of different interface charge densities have been investigated for the three termination techniques respectively. According to the previous reports, the JTE is quite sensitive to the implanted dose, so the blocking capability of each termination structure with different implanted doses is also simulated. The results show that when interface charge is considered, the SM-JTE always shows an enormous advantage over the other two junction termination structures, however the interface charge densities varied. The space-modulated JTE is also applicable to the power planar devices such as MOSFETs and IGBTs, which would provide a very promising lower fabrication cost. (paper)