The impact of bias temperature instability for direct-tunneling ultra-thin gate oxide on MOSFET scaling

This paper presents a new reliability scaling scenario for CMOS devices with direct-tunneling ultra-thin gate oxide. Device degradation due to bias-temperature instability (BTI) was studied. First, the stress voltage dependence of BTI results indicate that the direct-tunneling electron and/or hole transport does not play a major role in the degradation mechanism. Secondly, it was found that the threshold voltage change caused by BTI for the PMOSFET limits the device lifetime, which is shorter than that defined by hot-carrier induced degradation for the NMOSFET. It originates from the difference of supply voltage dependence between BTI and hot-carrier degradation.