A new observation of the germanium outdiffusion effect on the hot carrier and nbti reliabilities in sub-100nm technology strained-Si/SiGe CMOS devices

Abstract

In this paper, the evidence of SiGe layer induced trap generation and its correlation with enhanced degradation in strained-Si/SiGe CMOS devices have been reported for the first time. First, a new two-level charge pumping(CP) curve has been demonstrated to identify the Ge outdiffusion effect. Secondly, enhanced degradation in strained-Si devices has been clarified based on experimental results. Both n- and p-MOSFE's exhibit different extent of HC degradation effect. This is attributed to the difference in their mobility enhancement as well as additional traps coming from the Si/SiGe interface. Finally, temperature dependence of HC and NBTI has been examined for both strained-Si and bulk devices. Sophisticated measurement techniques, charge pumping and gated-diode (GD) measurements, have been employed to understand the generated interface traps. Results show that strained-Si device is less sensitive to the temperature and has a chance for better NBTI reliability if we have a good control of the strained-Si/SiGe interface, such as through low temperature gate oxide process or better S/D junction formation.