功率MOSFET雪崩击穿问题分析

Analysis on Avalanche Breakdown of Power MOSFET

分析了功率 MOSFET 雪崩击穿的原因,以及 MOSFET 故障时能量耗散与器件温升的关系。和传统的双极性晶体管相比,反向偏置时 MOSFET 雪崩击穿过程不存在"热点"的作用,而电气量变化却十分复杂。寄生器件在 MOSFET 的雪崩击穿中起着决定性的作用,寄生晶体管的激活导通是其雪崩击穿的主要原因。在 MOSFET 发生雪崩击穿时,器件内部能量的耗散会使器件温度急剧升高。

The failure reasons of MOSFET,and the relations between the energy dissipation and device temperature rise for MOSFET's failure are analyzed.There are no thermal points during the avalanche breakdown for a reverse-biased power MOSFET,and the effect of the electrical change in MOSFET is complex compared with bipolar transistor.Parasitic devices in MOSFET play an important part in MOSFET's failures,and the excitation and conduction of the parasitic transistor is the main reason of the avalanche breakdown of power MOSFET.At avalanche breakdown,because of the energy dissipation,the MOSFET's temperature will have a steep rise.