A Novel Charge-Imbalance Termination for Trench Superjunction VDMOS

A novel charge-imbalance termination region for high-voltage trench superjunction (SJ) vertical diffused MOSFETs (SJ-VDMOSs) is proposed and discussed in this letter. Its breakdown characteristics are investigated theoretically and experimentally. A simple and meaningful analytical-solution method is proposed, and it agrees with the simulation and experimental results. As a result, the novel imbalance termination can suppress the edge-drift potential more effectively than the conventional one in the off state. When the trench SJ-VDMOS was compared with a conventional termination structure of the same size, the device improved the breakdown voltage (BV) by about 8% using the proposed termination structure. Experimentally, a BV of 715 V was obtained in the trench SJ-VDMOS with a 35-μm trench on a 45-μm epitaxial layer and a 90- μm termination region.