不同栅压下Si-n型金属氧化物半导体场效应管总剂量效应的瞬态特性仿真

Transient characteristics simulation of total ionizing dose effect on Si n-metal-oxide-semiconductor field effect transistor under different gate voltage

为了实现半导体器件在电离辐射环境中电学特性的动态退化过程,本文基于总剂量效应中陷阱对载流子的俘获/发射过程,建立了Si-n型金属氧化物半导体场效应管总剂量效应的瞬态特性数值模型.仿真了不同栅极偏压下,器件电学特性随累积总剂量的上升而造成的器件退化效应,并提取了Si/SiO_(2)界面和栅氧化层中陷阱电荷的变化.仿真发现,随着累计总剂量的上升,两个位置处陷阱电荷的数量都趋向于饱和.当辐照中栅极偏压为正时,器件阈值电压的退化幅度显著高于辐照偏压为负时的退化幅度.无论是辐照过程中栅极加正偏压还是反偏压,都表现出阈值电压的退化幅度随着偏压幅值上升先上升再下降的趋势.栅极偏压对器件辐照后的退火效应也有一定的影响,在退火过程中如果栅极偏压不为零,器件退火后的电学特性恢复幅度比零偏压下的要低一些.

In this work,we establish a novel numerical model of total ionizing dose effect and use it to simulate the radiation degradation of Si n-metal-oxide-semiconductor field effect transistor(NMOSFET)under different bias voltages.The model is based on the capture/emission process of traps,and is used to simulate the transient characteristics of semiconductor devices under total ionizing dose effect.In the simulation,the changes of trapped holes in Si/SiO_(2)interface and gate oxide layer are extracted,and it is found that the number of trapped holes at different positions tends to be saturated with the increase of the total dose.When the radiation bias voltage is positive,the degradation amplitude of the threshold voltage is significantly higher than that when the radiation bias voltage is negative.Whether the gate is applied with positive bias or negative bias during the radiation,the degradation amplitude of the threshold voltage shows a trend of first increasing and then decreasing with the increase of the absolute value of radiation bias voltage.Radiation bias voltage also has a certain effect on the annealing effect after radiation.If a gate bias voltage is applied to the device during the annealing,the electrical characteristics recovery amplitude of the device is lower than that under zero bias voltage.