New understanding of LDD NMOS hot-carrier degradation and device lifetime at cryogenic temperatures

Abstract

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-case gate voltage condition is reported at low temperatures. New understanding of the hot-carrier mechanisms at low temperatures is also discussed. Low temperature effects such as freeze-out are shown to have important contributions to the hot-carrier behavior at low temperatures. A trend is identified for the first time which suggests important consequences for the hot-carrier reliability of deep sub-micron channel length MOSFETs under normal operating temperatures.