HOT-CARRIER DEGRADATION OF CMOS INVERTERS AND RING OSCILLATORS AT 77K

The impact of hot-carrier (HC) stress on CMOS inverters at 77K was exa mined as a function of temperature. It was found that the degradation in inverter propagation delay was about one order less than that of th e device transconductance degradation. Activation energy (E(A)) of pro pagation delay exhibited two distinct values from 295K to 77K, with a transition at around 175K for virgin and stressed inverters. The impro vement of propagation delay and voltage transfer characteristic (VTC) at 77K compared to 295K was larger for virgin than HC stressed inverte rs.