GaN高电子迁移率晶体管强电磁脉冲损伤效应与机理∗

摘要

提出了一种新型GaN异质结高电子迁移率晶体管在强电磁脉冲下的二维电热模型，模型引入材料固有的极化效应，高场下电子迁移率退化、载流子雪崩产生效应以及器件自热效应，分析了栅极注入强电磁脉冲情况下器件内部的瞬态响应，对其损伤机理和损伤阈值变化规律进行了研究。结果表明，器件内部温升速率呈现出“快速-缓慢-急剧”的趋势。当器件局部温度足够高时(>2000 K)，该位置热电子发射与温度升高形成正反馈，导致温度急剧升高直至烧毁。栅极靠近源端的柱面处是由于热积累最易发生熔融烧毁的部位，严重影响器件的特性和可靠性。随着脉宽的增加，损伤功率阈值迅速减小而损伤能量阈值逐渐增大。通过数据拟合得到脉宽τ与损伤功率阈值P和损伤能量阈值E的关系。%As electromagnetic environment of semiconductor device and integrated circuit deteriorates increasingly, electro-magnetic pulse (EMP) of device and damage phenomenon have received more and more attention. In this paper, the damage effect and mechanism of the GaN high electron mobility field effect transistor (HEMT) under EMP are inves-tigated. A two-dimensional electro-thermal theoretical model of GaN HEMT under EMP is proposed, which includes GaN polarization effect, mobility degradation in large electric field, avalanche generation effect, and self-heating effect. The internal transient response of AlGaN/GaN HEMT is analyzed under the EMP injected into the gate electrode, and the damage mechanism is studied. The results show that the temperature of device keeps increasing, and the rate is divided into three stages, which present a tendency of “rapid-slow-sharp” till burn-out. The first rapid increasing of temperature is caused by the avalanche breakdown, and then rate becomes smaller due to the decrease of electric field. As the temperature is more than 2000 K, a positive feedback is formed between the hot electron emission and temper-ature of device, which causes temperature to sharply increase till burn-out. The maximum values of electric field and current density are located at the cylinder surface beneath the gate around the source, which is damage prone because of heat accumulation. Finally, the dependences of the EMP damage power, P , and the absorbed energy, E, on pulse width are obtained in a nanosecond range by adopting the data analysis software. It is demonstrated that the damage power threshold decreases but the energy threshold increases slightly with the increasing of pulse-width. The proposed formulas P =38τ−0.052 and E=1.1τ0.062 can estimate the high power microwave pulse-width dependent damage power threshold and energy threshold of AlGaN/GaN HEMT, which can provide a good prediction of device damage and a guiding significance for electromagnetic pulse resistance destruction.