Physical analysis for saturation behavior of hot-carrier degradation in lightly doped drain N-channel metal-oxide-semiconductor field effect transistors

This paper experimentally demonstrates that hot carrier degradation curves of lightly doped drain n-channel metal-oxide-semiconductor field effect transistors (LDDNMOSFETs) has universal behavior even if different stress conditions were applied. From this phenomena, we have proved that the Φ_it/E_m, the ratio of critical barrier for interface state generation to the maximum electric field, doesn’t change so that accurate lifetime prediction for drain avalanche hot carrier (DAHC) is possible using conventional log (τI_d) vs log (I_Sub/I_d) method even if the degradation vs stress time curves show a saturation behavior. We have modeled stressed LDD as an equivalent circuit which is comprised by a surface channel MOSFET and two buried channel MOSFETs. And various circuit simulations were done by mobility change of drain side buried channel MOSFET. As a result, a modified mobility model with a lower limit parameter for mobility degradation has been developed, which successfully describes the saturation behavior of device degradation.