20 kV SiC GTO关断失效机理研究

Investigation of Turn-off Failure Mechanism for 20 kV SiC GTO

碳化硅(SiC)可关断晶闸管(GTO)在感性负载关断过程中,过流应力会导致器件发生关断失败的现象,从而影响器件的可靠性,限制安全工作区(SOA)。此处通过Sentaurus-TCAD模拟软件对20kVSiCGTO不同初始关断电流的关断特性进行了研究,分析了引起关断失效的原因及其影响因素。结果表明,当关断电流密度达到-2400 A·cm^(-2)时,SiC GTO发生强烈的动态雪崩,产生稳定的电流丝,导致器件关断失效。另外,增加P^(+)缓冲层的掺杂浓度,动态雪崩效应被削弱,且器件关断时间减小了;而P^(+)缓冲层厚度的增加,对动态雪崩强弱几乎没有影响。外电路的门极电感由1nH增加为10nH,动态雪崩强烈,导致器件关断失败。

During the inductive turn off for silicon carbide(SiC)gate turn-off thyristor(GTO),overcurrent stress will cause the device to fail to turn-off,which will affect the reliability of the device and limit the safe operating area(SOA).The turn-off characteristics of 20 kV SiC GTO with different initial turn-off currents are investigated by Sentaurus-TCAD simulation software,and analyzed mechanism turn-off failure and influencing factors.Results show that,at the case of turn-off current density-2400 A·cm^(-2),a strong dynamic avalanche occurs in SiC GTO,which generates a stable current filament and thus the device turns-off fail.In addition,increases the doping concentration of the P^(+) buffer layer,the dynamic avalanche onset is weakened and the turn-off time of the device is reduced.It is almost no influence on dynamic avalanche onset when the thickness of P^(+) buffer layer increases.The gate inductance of external circuit is increased from 1 nH to 10 nH,leading to the dynamic avalanche onset becomes stronger and thus the device is failed to turn-off.