Physical Mechanism Underlying the Time Exponent Shift in the Ultra-fast NBTI of High-k/Metal gated p-CMOSFETs

摘要

In this study, ultra-fast methods were used to measure the threshold voltage shift (ΔVn_Tn) of the negative bias temperature instability (NBTI) in p-channel complementary metal oxide semiconductor field effect transistors (p-CMOSFETs) with a high-klmetal gate (HK/MG) stack. The voltage (Vg,str) and temperature (T) dependence of the NBTI time exponent (n) were studied under a wide range of stress conditions, and the results demonstrated a strong T dependence of n above room temperature (RT) and that the field reduction effect played an important role in determining the dependence of n on Vg,str and T. With the direct current current-voltage (DCIV) method, the similarity of n, activation energy (EA) and voltage acceleration factor (Γ) between the trap generation (ΔNn_Tn) and ΔVn_Tnindicates that ΔNn_Tnis the dominant subcomponent at higher values of T. The impact of the field reduction effect on the time exponents of ΔVn_Tnand ΔVn_Tn, En_An, and Γ were also investigated.