Electrothermal Effects on Hot Carrier Injection in n-Type SOI FinFET Under Circuit-Speed Bias

Electrothermal study of the n-type SOI Fin-FETs at 50-nm node is performed by analytical method and numerical algorithm. The self-heating effects (SHE) are investigated and validated by commercial software and other published analytical solutions. Further, the time-dependent thermal conduction equation is solved to get the temperature response under different signal stresses, including step pulse, AC signal, and circuit-speed random stress which is mimicked by the pseudorandom binary sequence (PRBS) signal. It is found that the PRBS signal leads to a lower transient temperature peak in the n-type FinFET of an inverter than the AC signal due to the less logic transitions in the PRBS, and signal with higher frequency induces worse SHE. According to the temperature response, hot-carrier injection (HCI)-induced threshold voltage shift (TVS) in the n-type FinFET of an inverter is further captured. It is shown that TVS under PRBS stress is much lower than that the AC case with the same frequency due to less logic transitions in PRBS signal, and the TVS becomes more severe with the increase of signal frequency. Although the gradual-width structure for n-type FinFET leads to a much lower static temperature, it does not help a lot to improve dynamic temperature and TVS when the inverter is biased by AC or PRBS signals.