Channel-length dependence of the generation of interface states and oxide-trapped charges on drain avalanche hot carrier degradation of HfSiON/SiO2 p-channel MOSFETs with strained Si/SiGe channel

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This paper evaluates how channel length L affects the drain avalanche hot carrier degradation (DAHC) degradation mechanism of HfSiON/SiO2 pMOSFETs that have strained Si/SiGe channel. DAHC degradation occurred as L was to reduced < 70 nm, and the amount of degradation increased as L decreased. In the early stage of stress, DAHC degradation increased positively due to generation of negative oxide charges –Qox, but gradually-generated interface states Nit neutralize –Qox, so a transition point occurs and eventually DAHC increases negatively after sufficient stress time ts. The distribution of DAHC degradation was also analyzed after ts = 4000, 40000 s. The effects of additional generation of –Qox and Nit on DAHC degradation contribute more near the drain edge than to the center region, and increase as L decreases. Therefore, further research on the DAHC degradation mechanism should be conducted to predict the reliability of HfSiON/SiO2 pMOSFETs with mechanical strain engineering.