Uniform shallow trenches termination design for high‐voltage VDMOS transistor

A new uniform shallow trenches termination (ST 2 ) with field plate for high‐voltage VDMOS transistor is proposed in this Letter. In ST 2 structure, the electric field near the source is decreased and the depletion region is extended by the field plate, besides, many electric field peaks are introduced in shallow trenches under the field plate and the average electric field strength is increased, both improve the characteristic of the breakdown voltage (BV). Simulation results show the BV of ST 2 VDMOS is 706 V with a termination length L d = 132 μm, which reaches 97% of that of the parallel‐plane junction, and the influence of the edge curvature effect is almost entirely eliminated. The ST 2 structure is compatible with conventional CMOS process with only one additional mask and its fabrication is low‐cost.