600V VDMOS器件的反向恢复热失效机理

Thermal failure mechanism of 600V VDMOS during reverse recovery

为了研究VDMOS器件体二极管在反向恢复过程中的失效机理,详细分析了600 V VDMOS器件体二极管的工作过程,采用TCAD模拟软件研究了体二极管正向导通和反向恢复状态下的载流子密度分布及温度分布情况.模拟结果表明,VDMOS器件的体二极管在正向导通时,器件终端区同样会贮存大量的少数载流子,当体二极管从正向导通变为反向恢复状态时,贮存的少数载流子会以单股电流的形式被抽取,使得VDMOS器件中最靠近终端位置的原胞中的pbody区域温度升高,从而导致该区域寄生三极管基区电阻增大、发射结内建电势降低,最终触发寄生三极管开启,造成VDMOS器件失效.分析结果与实验结果一致.

In order to study the failure mechanism of the body diode in a vertical double-diffused metal oxide semiconductor （VDMOS）device,the reverse-recovery phenomenon of the body diode in 600 V VDMOS is investigated in detail.The distributions of carrier density and temperature of the VDMOS during the forward conduction condition and reverse recovery condition are analyzed by the TCAD simulation tools.The simulation results show that lots of the minority carriers can be stored in the termination during the on-state mode of the body diode.When the diode switches from the for-ward conduction mode to the reverse blocking mode,the minority carriers stored in the termination will be removed as current in a single path.As a result,the temperature in the p-body region of the cell near the termination is increased,which leads to the increase of the base resistance in the parasit-ic bipolar and the decrease of the built-in potential of the emitter junction.The parasitic bipolar can be triggered and the VDMOS device fails.The analytical results agree with the measurements well.