pMOSFET的NBTI退化机理及内在影响因素

NBTI degradation mechanism and its influence factors for pMOSFET

研究了P型MOSFET的NBTI效应退化机理,以及栅氧化层电场和沟道载流子浓度对NBTI效应的影响.首先,通过电荷泵实验对NBTI应力带来的p M OSFET的界面损伤进行了测试,并利用TCAD仿真软件对测试结果进行分析,结果表明该器件的NBTI退化主要由其沟道区的界面态产生引起,而电荷注入的影响相对可以忽略.然后,通过施加衬底偏置电压的方法实现了增加器件栅氧化层电场但保持沟道载流子浓度不变的效果,进而研究了栅氧化层电场和沟道载流子浓度2个内在因素分别对NBTI退化的影响.最后,通过对比不同栅极电压和不同衬底偏置电压条件下器件的2个内在影响因素变化与NBTI退化的关系,证明了p MOSFET的NBTI效应主要由器件的栅氧化层电场决定,沟道载流子浓度对器件NBTI效应的影响可以忽略.

The negative bias temperature instability （NBTI） degradation mechanism and the influ- ences of the gate oxide field and the channel carrier density on the NBTI are investigated for a P-type metallic oxide semiconductor field effect transistor （MOSFET）. First, the interface damages induced by the NBTI stresses are measured by the charge pumping （CP） experiments. Through analyzing CP results with the technology computer aided design （TCAD） simulations, it is shown that the NBTI degradation is dominated by the interface states generation in the channel region, while the influence of charge injection is relatively ignorable. Then, by applying the substrate bias, the constant channel carrier density is maintained when the gate oxide electric field is increased. As a result, the influ- ences of gate oxide electric field and channel carder density on the NBTI degradations are investiga- ted, respectively. Finally, by comparing the NBTI degradation and the influence factors variations under different substrate bias and gate bias conditions, it is proved that the NBTI effect of the pMOSFET is determined by the gate oxide electric field, and the influence of the channel carrier density on the NBTI is relatively negligible.