A COMPARISON OF MOSFETS AGING UNDER DC,AC AND ALTERNATING STRESS CONDITIONS

The effects of static, alternating and dynamic stress conditions on th e degradation rate of 0.8mum n- and p-channel LDD MOS transistors have systematically been investigated and compared. The shifts of the thre shold voltage, transconductance, linear drain current and charge pumpi ng current were used to monitor the transistor degradation. The result s suggest that the aging induced by a dynamic stress cannot be directl y explained with static stress models, essentially because it is highl y dependent on a larger number of parameters (biases and durations of the top and bottom levels of the pulses, transient times). The correla tion of static and dynamic stresses also clarifies the degradation mec hanisms, in particular the role of hot holes in the generation of inte rface states.