Design Of Uniaxial Strained Si PMOS And Research On NBTI Effect

As the feature sizes of IC entered into the nanoscale, it is more and more difficult forconventional CMOS to scale down. Strained Si has a tunable bandgap, higher carriermobility, etc., therefore was considered the most promising new technology to continueMoore’s Law. Relative to biaxial strain process, the uniaxial strain is simpler, lower cost,and is more compatible with the mature Si technology. Therefore, it is a hot spot tostudy the uniaxial strained Si device at home and abroad.This paper focuses on uniaxial strained Si PMOS, studied the SiN-induced strain,SiGe induced strain and compound-induced strain, and NBTI effect of the small sizePMOS.Firstly, this paper studied SiN-induced strain. Designed structure and processes ofPMOS in Sentaurus Simulation. Simulated its electrical properties, and the results showthe performance of SiN-induced strain PMOS improved significantly. Further studiedthe SiN film stress, thickness, gate length, Poly height, side wall structure impact onPMOS performance.Secondly, this paper studied SiGe-induced strain. The results of simulation showedthe performance of SiGe-induced PMOS is also impoved significantly. Other studied themole fraction of Ge, SiGe junction depth, height and gate length impact on PMOSperformance. In addition, this paper studied the combination of SiN-induced strain andSiGe-induced strain, called compound-induced strain, and the results show that PMOSperformance was improved more significantly.Finally, this paper studied PMOS NBTI effect. Studied generation mechanism ofNBTI and degradation model, NBTI degradation due to interface states, leading todegradation of PMOS device performance, and results show that: temperature, voltage,the diffusion coefficient of hydrogen were all factors, in which the most sensitive factoris temperature, The higher temperature and gate voltage, and the faster hydrogendiffusion, the more severe device performance degradation. In addition, this paper alsostudied gate oxide thickness impact on NBTI effect, and the results show: the thinnergate oxide, the smaller device performance degradation due to NBTI. In order tosuppress the PMOS NBTI effect, this article gives optimization methods for designingbetter performance, higher reliability PMOS in future.