新型缓冲层分区电场调制横向双扩散超结功率器件

为了突破传统横向双扩散金属-氧化物-半导体器件(lateral double-diffused MOSFET)击穿电压与比导通电阻的极限关系,本文在缓冲层横向双扩散超结功率器件(super junction LDMOS-SJ LDMOS)结构基础上,提出了具有缓冲层分区新型SJ-LDMOS结构.新结构利用电场调制效应将分区缓冲层产生的电场峰引入超结(super junction)表面而优化了SJ-LDMOS的表面电场分布,缓解了横向LDMOS器件由于受纵向电场影响使横向电场分布不均匀、横向单位耐压量低的问题.利用仿真分析软件ISE分析表明,优化条件下,当缓冲层分区为3时,提出的缓冲层分区SJ-LDMOS表面电场最优,击穿电压达到饱和时较一般LDMOS结构提高了50%左右,较缓冲层SJ-LDMOS结构提高了32%左右,横向单位耐压量达到18.48 V/μm.击穿电压为382 V的缓冲层分区SJ-LDMOS,比导通电阻为25.6 mΩ·cm2,突破了一般LDMOS击穿电压为254 V时比导通电阻为71.8 mΩ·cm2的极限关系.

New super junction lateral double-diffused MOSFET with electric field modulation by differently doping the buffered layer

In order to break through the limit relationship between the breakdown voltage and specific on-resistance for LDMOS (lateral double-diffused MOSFET), a new super junction LDMOS is proposed with the electric field modulation by differently doping the buffered layer in this paper for the first time based on the buffered SJ-LDMOS. The new electric field introduced by the differently doping buffered layer, owing to the electric field modulation, is brought to the surface electric field of SJ-LDMOS, which alleviates a low lateral breakdown voltage due to the uneven electric field distribution for the LDMOS affected by the vertical electric field. Through the ISE simulation, the results are obtained that the surface electric field is optimized for the proposed SJ-LDMOS when the number of differently doping buffered layers is three. The saturated breakdown voltage for the new SJ-LDMOS is increased by about 50% compared with that for conventional LDMOS, and improved by about 32% compared with that for buffered SJ-LDMOS. The lateral breakdown voltage for unit length is increased to 18.48 V/μm. For the proposed SJ-LDMOS, the specific on-resistance is 25.6 mΩ· cm² with a breakdown voltage of 382 V, which already breaks the limit relationship of 71.8 mΩ·cm² with a breakdown voltage of 254 V in the conventional LDMOS.
Keywords： lateral double-diffused MOSFET super junction breakdown voltage specific on resistance