IGBT在关断过程中所发生的动态雪崩现象是导致其失效的重要原因之一.为研究IGBT动态雪崩失效机理,利用Silvaco软件对其进行仿真分析.通过对动态雪崩击穿机制、电流密度分布和温度分布的仿真分析,得出动态雪崩可以产生移动的电流丝和移动十分缓慢或固定不动的"死丝".引起器件失效的是动态雪崩形成的死丝,死丝会导致IGBT内局部温度的急剧增加,最终因局部温度过高烧毁器件导致IGBT的失效.在此基础上分析了死丝产生的原因并进一步提出防止IGBT动态雪崩失效的具体措施.
The phenomenon of dynamic avalanche occurring during the IGBT turn-off process is one of the impor-tant reasons for its failure.To study the dynamic avalanche failure mechanism of IGBT,the Silvaco software was used to simulate and analyze this mechanism.Through the simulation and analysis of the breakdown mechanism,current density distribution and temperature distribution of dynamic avalanche,it is concluded that dynamic avalanche can generate moving current filaments and dead filaments which are either moving slowly or fixed.However,the failure of the device is caused by the dead filaments formed by dynamic avalanche.The dead filaments will lead to a sharp increase of local temperature in the IGBT,and the IGBT will eventually fail because the local temperature is too high to burn the device.On this basis,the causes of dead filaments are analyzed,and specific measures to prevent the dynamic avalanche failure of IGBT are also put forward.