功率LIGBT热载流子退化机理及环境温度影响

Hot-carrier degradation mechanism and influence of ambient temperature for power LIGBT

研究了横向绝缘栅双极型晶体管(LIGBT)的热载流子退化机理及环境温度对其热载流子退化的影响.结果表明,器件的主导退化机制是鸟嘴处大量界面态的产生,从而导致饱和区阳极电流Iasat和线性区阳极电流Ialin存在较大的退化的主要原因,同时,由于Ialin的分布比Iasat的分布更靠近器件表面,故Ialin的退化比Iasat的退化更严重;而器件沟道区的碰撞电离和热载流子损伤很小,使得阈值电压Vth在应力前后没有明显的退化.在此基础上,进一步研究了环境温度对LIGBT器件的热载流子退化的影响.结果表明,LIGBT呈现正温度系数,且高温下LIGBT的阈值电压会降低,使得相同应力下其电流增大,导致器件碰撞电离的增大,增强了器件的热载流子损伤.

The mechanism of hot-carrier degradation for lateral insulated gate bipolar transistor（ LIGBT） and the influence of ambient temperature are investigated. The results indicate that the main degradation mechanism is the generation of a large number of interface states at the beak of LIGBT,which leads to the large decreases of the saturation-region anode current Iasatand the linearregion anode current Ialin. Meanwhile,the distribution of Ialinis much closer to the device surface comparing with that of Iasat,so the degradation of Ialinis more serious than that of Iasat. In the channel region,the impact ionization and the hot carrier damage are tiny; as a result,the threshold voltage Vthremains constant before and after the stress. Moreover,the influence of ambient temperature on the hot carrier degradation of LIGBT is also investigated. LIGBT shows positive temperature coefficient,and the decreased threshold voltage under the high temperature condition induces the increase of the current of LIGBT under the same stress,which leads to the increase of impact ionization.Thus,finally enhanceing the hot-carrier damage of LIGBT.