γ射线总剂量辐照效应对应变Si p型金属氧化物半导体场效应晶体管阈值电压与跨导的影响研究∗

摘要

分析了双轴应变Si p型金属氧化物半导体场效应晶体管(PMOSFET)在γ射线辐照下载流子的微观输运过程，揭示了γ射线的作用机理及器件电学特性随辐照总剂量的演化规律，建立了总剂量辐照条件下的双轴应变Si PMOSFET阈值电压与跨导等电学特性模型，并对其进行了模拟仿真。由仿真结果可知，阈值电压的绝对值会随着辐照总剂量的积累而增加，辐照总剂量较低时阈值电压的变化与总剂量基本呈线性关系，高剂量时趋于饱和；辐照产生的陷阱电荷增加了沟道区载流子之间的碰撞概率，导致了沟道载流子迁移率的退化以及跨导的降低。在此基础上，进行实验验证，测试结果表明实验数据与仿真结果基本相符，为双轴应变Si PMOSFET辐照可靠性的研究和应变集成电路的应用与推广提供了理论依据和实践基础。%In this work, the carrier microscopic transport process of biaxial strained Si p-channel metal-oxide-semiconductor field-effect transistor (PMOSFET) underγ-ray radiation has been studied. Effect ofγ-ray on devices and the relationship between the variation of device electrical characteristics and the total dose are investigated. A model for considering the degradation of threshold voltage and transconductance due to the total dose radiation is established. Based on this model, numerical simulation has been carried out. Results show that the threshold voltage of PMOSFET decreases with increasing radiation dose. At a lower total dose, the threshold voltage decreases linearly. However, at a higher total dose, it becomes saturated. The degradation can be explained by the generation of trapped charges which increase the impact possibility of carriers in the channel and induce the reduction of mobility and transconductance accordingly. Finally, the simulation results are compared with the experimental data. A good agreement is observed, indicating the validation of our proposed model.