Bias Dependent Hot-Carrier Reliability and Lifetime over a Wide Temperature Range

CMOS device lifetime is determined at tempcratures of 77 K, 150 K, and 218 K. Due to enhanced hot carrier degradation, lower operating voltages are necessary at lower tcmperatures. A novel, two-slope lifetime behavior is observed at 77 K, emphasizing the need to stress devices near the desired operating voltage. The dominant degradation mechanism depends on the temperature and drain bias. Above a certain voltage, electron injection dominates. Bclow this bias, intcrface-state gcncration leads to a shoncr lifetime. Thc voltagc at which this transition occurs is a function of temperature and is of the same order as the power supply voltage at intermediate tcmperatures. This explains the change of dominant degradation mechanism from interface states (at 300 K) to electron injection (at 77 K).