Cryogenic behavior of scaled CMOS devices

Performance enchancements of scaled CMOS devices are studied at room and liquid nitrogen temperatures. The extent of propogation delay improvement at low temperature is limited by velocity saturation as device channel lengths are decreased and or the supply voltage is increased. Liquid nitrogen temperature operation increases low field mobility by a factor of 4 while the saturation velocity increases only 30%. An analytical model is developed for device switching speed which includes velocity saturation effects. The model accurately predicts measured propogation delay on scaled CMOS delay chains with channel lengths down to 0.5 µm.