Physical model of drain conductance, gd, degradation of NMOSFET´s due to interface state generation by hot carrier injection

Degradation of analog device parameters such as drain conductance, g_d, due to hot carrier injection has been modeled for NMOSFET´s. In this modeling, mobility reduction caused by interface state generation by hot carrier injection and the gradual channel approximation were employed. It has been found that g_d degradation can be calculated from linear region transconductance, g_m, degradation which is usually monitored for hot carrier degradation of MOSFET´s. The values of g_d degradation calculated from g_m degradation fit well to the measured values of g_d degradation The dependence of the g_d degradation lifetime on L_eff has been also studied, this model also provides an explanation of the dependence on L_eff. The model is then useful for lifetime predictions of analog circuits in which g_d degradation is usually more important than g_m degradation