The Study of the Main Junction of the VDMOS Termination

In this paper, based on the 500 V VLD (Variation of Lateral Doping) termination, a modified VLD structure is proposed to improve the efficiency of the termination, in which the adjacent cell is employed as the main junction of the termination. And then the two terminations are simulated by Sentaurus software. The simulation results show that the breakdown voltage (BV ) of the proposed termination is slightly, and the electric field distribution of the two terminations are very similar. Therefore, it is feasible and effective to employ the adjacent cell as the main junction. Based on this, the VLD terminal structure is optimized, and its length is reduced by 12 µm (from 89 µm to 77 µm based on the depletion layer boundary). Moreover, the breakdown voltage is just reduced by 3.5 V (from 511.1 V to 507.6 V). So, it can be considered that the termination length can be effectively shortened without the degradation of breakdown voltage by this way, which will offer an excellent scheme to optimize the termination.