CRYOGENIC BEHAVIOR OF SCALED CMOS DEVICES.

Performance enhancements of scaled CMOS devices are studied at room and liquid nitrogen temperatures. The extent of propagation 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 propagation delay on scaled CMOS delay chains with channel lengths down to 0. 5 mu m.