Improvement of hot-carrier resistance and radiation hardness of nMOSFETs by irradiation-then-anneal treatments

The improvement of hot-carrier resistance and radiation hardness in n-channel MOSFETs by a novel technique is studied. This technique includes a Co-60 (1 M rad) irradiation and a subsequent anneal in N2 at 400°C for 10 min. The hot-carrier-induced instability and the radiation-induced degradation in MOSFETs are examined from the shifts of threshold voltage, transconductance, and drain current. It is observed that the sample after irradiation-then-anneal treatment shows more resistance to hot carrier and radiation damage than that without treatment. The effects are explained by a model involving strain relaxation induced near the SiO2/Si interface by irradiation. © 1991.