Novel Reduced ON-Resistance LDMOS With an Enhanced Breakdown Voltage

A novel Lateral Double-diffusion Metal Oxide Semiconductor (LDMOS) is proposed to enhance its breakdown voltage (BV) and reduce specific ON-resistance (RON,sp), and its mechanism is investigated by simulation. It features a junction field plate (JFP) at surface and an N+ floating layer (NFL) in the P-substrate. The lateral variation doping JFP not only modulates the surface electric field (E-field) distribution to improve the BV, but also allows a high N-drift doping concentration and thus reduces the RON,sp owing to the charge compensation effect between the N-drift region and P region in the JFP in the OFF-state. The heavily doped NFL is not fully depleted and thus is an equipotential layer in the lateral direction. It thus reshapes the equipotential contours at both the source and drain sides, avoiding the E-field concentration and premature breakdown under the drain; moreover, the additional vertical diode is induced between the NFL and P-sub and it thus extends the depletion width in P-sub, both of which increase the BV. The RON,sp and BV of the JFP-NFL LDMOS is improved by 47% and 63%, respectively, compared with those of a conventional LDMOS at the same dimension. The JFP-NFL LDMOS achieves a superior tradeoff between RON,sp and BV to the different single-, double-, and triple-REduced SURface Field LDMOSFETs with planar technology.