具有N型缓冲层REBULF Sup er Junction LDMOS

摘要

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.%针对功率集成电路对低损耗LDMOS (lateral double-diffused MOSFET)类器件的要求，在N型缓冲层super junction LDMOS (buffered SJ-LDMOS)结构基础上，提出了一种具有N型缓冲层的REBULF (reduced BULk field) super junction LDMOS结构。这种结构不但消除了N沟道SJ-LDMOS由于P型衬底带来的衬底辅助耗尽效应问题，使super junction的N区和P区电荷完全补偿，而且同时利用REBULF的部分N型缓冲层电场调制效应，在表面电场分布中引入新的电场峰而使横向表面电场分布均匀，提高了器件的击穿电压。通过优化部分N型埋层的位置和参数，利用仿真软件ISE分析表明，新型REBULF SJ-LDMOS的击穿电压较一般LDMOS提高了49%左右，较文献提出的buffered SJ-LDMOS结构提高了30%左右。