New REBULF super junction LDMOS with the N type buffered layer

Abstract

In this paper, a new REBULF (reduced BULk field) SJ-LDMOS (lateral double-diffused MOSFET) is proposed with the N type buffered layer based on the buffered SJ-LDMOS for the low loss of LDMOS used in the power integrated circuits. In this structure, the problem of the substrate-assisted depletion, produced due to the P-type substrate for the N-channel SJ-LDMOS, is eliminated by the N-type buffered layer. The charges for the N-type and P-type pillars are depleted completely. Moreover, a new electric field peak is introduced into the surface electric field distribution, which makes the lateral surface electric field uniform. The breakdown voltage is improved for the REBULF SJ-LDMOS in virtue of the ISE simulation results. By optimizing the location and parameters of the N-type buried layer, the breakdown voltage of REBULF SJ-LDMOS is increased by about 49% compared with that of the conventional LDMOS, and improved by about 30% compared with that of the buffered SJ-LDMOS.