Reduction of the radiation sensitivity of MOS structures by irradiation-anneal cycle treatment

Abstract

The density of the interface traps in MOS devices has been studied after repeated cycles of irradiation and anneal treatment. Each cycle consists of gamma-irradiation with a 4.6 × 10 3 rad dose and an anneal at 200°C for 10 min. Then all devices were simultaneously gamma-irradiated with a 4.48 × 10 6 rad dose. Results obtained by high frequency and quasistatic C/V methods show that the radiation sensitivity correlates with these cyclic treatments. It is found that the radiation hardness of the MOS structures first increases with the number of repeated treatments and then a saturation is reached. A possible explanation of the results is proposed.