Study On Hot-Carrier-Induced Reliability Priblems And Lifetime Prediction Method In PMOSFET's

Hot-carrier effect is a major reliability failure mechanism of MOS devices and circuits. Most of the studies about hot-carrier effects concentrated on NMOSFET rather than PMOSFET simply because hot-carrier-induced reliability problems of NMOSFET axe always more serious than those of PMOSFET in general. However, as the channel length decreases, hot-carrier-induced degradation of PMOSFET becomes more and more serious, and have become an important reliability limitation of CMOS circuits, so it is required that hot-carrier effects of PMOSFET should be studied deeply. First, the degradation characteristics of several typical device parameters with stress time are studied, and the growth mechanism of hot-carrier-induced device damage is studied. Also, High electric field annealing of stressed PMOSFET and detrapping of trapped electrons on the gate oxide are studied deeply. It is shown that detrapping under negative gate voltage is faster than detrapping under positive gate voltage, so the recovery of device characteristics under negative gate voltage is more obvious. Degradation characteristics of gate current and substrate current during stress are studied, and an accurate analytic degradation model of gate current is presented. Characterization methods of hot-carrier-induced degradation in PMOSFET by total injected charge are studied, and a new degradation monitor is proposed. Finally, a unified degradation model of different device parameters is presented for accurate prediction of device degradation and lifetime.