High-k Dielectric Assisted Trench Termination of the 4H-SiC Super Junction Device for Improved Avalanche Capability

The conventional trench termination for the 4HSiC sidewall-implanted Super Junction device has relatively low avalanche capability and the devices can fail destructively under abnormal operating conditions. In this paper, a novel high-k dielectric assisted trench termination is proposed. The high-k dielectric TiO2 is incorporated into the SiO2-filled trench. TCAD simulations are conducted to validate the efficacy of the proposed termination. The results show that with the proposed termination, the peak electric field is pushed to the edge of the TiO2 region, preventing breakdown at the corners of the active region edge; at the same time, the leakage current flows uniformly from the active region, thus improving the avalanche current; in addition, the addition of TiO2 to the terminator does not reduce the breakdown voltage. Moreover, the dimensions of the TiO2 are optimized in terms of the maximum current density. By taking the dielectric strength into consideration, the optimum depth and length of the TiO2 region are found to be 0.6μm and 2μm, respectively.