关态应力下P-MOSFETs的退化

研究了沟长从0.525μm到1.025μm 9nm厚的P-MOSFETs在关态应力(Vgs＝0，Vds＜0)下的热载流子效应．讨论了开态和关态应力．结果发现由于在漏端附近存在电荷注入，关态漏电流在较高的应力后会减小．但是低场应力后关态漏电流会增加，这是由于新生界面态的作用．结果还发现开态饱和电流和阈值电压在关态应力后变化很明显，这是由于栅漏交叠处的电荷注入和应力产生的界面态的影响．Idsat的退化可以用函数栅电流（Iｇ）乘以注入的栅氧化层电荷数（Qinj）的幂函数表达．最后给出了基于Idsat退化的寿命预测模型．

Degradation of P-MOSFETs Under Off-State Stress

The hot carrier effects under off-state stress mode (Vgs=0,Vds＜0) have been investigated on 9nm P-MOSFETs with channel length varying from 1.025μm to 0.525μm.Both on-and off-state currents are discussed.It is found that the off-state leakage current decreases after a higher voltage stressing,which is induced by the charge injection occurred close to the drain junction.However,the leakage current increases after a lower voltage stressing because of the newly generated interface traps.It is also found that the on state saturation current and threshold voltage degrade significantly with the stress time,which we believe is due to the charges injected near the gate-drain overlapping region and/or the stress-induced interface trap generation.The degradation of Idsat can be expressed as a function of the product of the gate current (Ig) and the number of charges injected into the gate oxide (Qinj)in a simple power law.Finally,a lifetime prediction model based on the degradation of Idsat is proposed.