Novel LDMOS Optimizing Lateral and Vertical Electric Field to Improve Breakdown Voltage by Multi-Ring Technology

Abstract

A novel lateral double-diffused MOSFET with multi-ring substrate (M-R LDMOS) is proposed. New high electric field peaks are introduced by the M-R due to the effect of the electric field modulation, which makes the lateral and vertical electric field distributions more uniform at the same time. As a consequence, the breakdown voltage (BV) of M-R LDMOS is enhanced significantly. The simulation result shows that the BV of M-R LDMOS is 566 V with the drift region length of $30~\mu \text{m}$ . Furthermore, the figure-of-merit of M-R LDMOS is 3.05 MW/cm2, increased by 190%, 45%, and 24.5% in comparison with the conventional LDMOS, the step doping drift LDMOS, and the assisted deplete-substrate layer LDMOS, respectively. M-R LDMOS has a much better performance. In addition, the proposed M-R LDMOS uses the highly doped substrate ( $3\times 10^{15}$ cm−3), which significantly reduces the cost of substrate.