高电子迁移率晶体管微波损伤仿真与实验研究

针对AlGaAs/InGaAs型高电子迁移率晶体管,利用TCAD半导体仿真工具,从器件内部空间电荷密度、电场强度、电流密度和温度分布变化分析出发,研究了从栅极注入1 GHz微波信号时器件内部的损伤过程与机理。研究表明,器件的损伤过程发生在微波信号的正半周,负半周器件处于截止状态;器件内部损伤过程与机理在不同幅值的注入微波信号下是不同的。当注入微波信号幅值较低时,器件内部峰值温度出现在栅极下方靠源极侧栅极与InGaAs沟道间,由于升温时间占整个周期的比例太小,峰值温度很难达到GaAs的熔点;但器件内部雪崩击穿产生的栅极电流比小信号下栅极泄漏电流高4个量级,栅极条在如此大的电流下很容易烧毁熔断。当注入微波信号幅值较高时,在信号正半周的下降阶段,在栅极中间偏漏极下方发生二次击穿,栅极电流出现双峰现象,器件内部峰值温度转移到栅极中间偏漏极下方,峰值温度超过GaAs熔点。利用扫描电子显微镜对微波损伤的高电子迁移率晶体管器件进行表面形貌失效分析,仿真和实验结果符合较好。

Simulation and experiment research on high electron mobility transistor microwave damage

The damage process and mechanism of the typical AlGaAs/InGaAs structure high electron mobility transistor by injection of 1 GHz microwave signals from the gate were studied with TCAD based on the distribution of the space charge density, electric field, current density and temperature. The results showed that the gate current rapidly increased because of avalanche breakdown which was 4 orders higher than the gate leakage current under small signals and the gate finger was extremely easy to burn and melt by such high current in the positive semi-cycle of microwave signals; the internal peak temperature of the device appeared between the InGaAs channel and gate near the source below the gate; when the amplitude of the microwave signals was high enough, during the fall time of the positive semi-cycle, the second breakdown occurred below the central gate inclining to the drain which caused double-peak phenomenon of the gate current, and the internal peak temperature of the device shifted to the above position and surpassed the GaAs melting point. Failure analysis of high electron mobility transistor devices damaged by microwaves was carried out with scanning electron microscope and the simulation results were well consistent with the experiment results.