NEW UNDERSTANDING OF LDD NMOS HOT-CARRIER DEGRADATION AND DEVICE LIFETIME AT CRYOGENIC TEMPERATURES

This work shows that the worst-case gate voltage stress condition for LDD nMOSFETs is a strong function of the channel length, drain voltage , and operating temperature. A new cross-over behavior of the worst-ca se gate voltage condition is reported at low temperatures. New underst anding of the hot-carrier mechanisms at low temperatures is also discu ssed. Low temperature effects such as freeze-out are shown to have imp ortant contributions to the hot-carrier behavior at low temperatures. A trend is identified for the first time which suggests important cons equences for the hot-carrier reliability of deep sub-micron channel le ngth MOSFETs under normal operating temperatures. (C) 1997 Elsevier Sc ience Ltd.