Radiation damages of polycrystalline silicon films and npn Si transistors by high-energy particle irradiation

The degradation of polycrystalline silicon films, subjected to 20-MeV alpha ray irradiation, is studied. The radiation source dependence of the perfor mance degradation is attributed to the difference of mass and the probabili ty of nuclear collisions for the formation of lattice defects. The trap den sity for alpha rays is larger than for protons and that a negligible fluenc e dependence is observed, It is concluded that the degradation of the poly- Si films by high-energy particle irradiation is caused by the induced latti ce defects in the grain itself rather than at its boundaries. The degradati on of npn Si transistors, subjected to gamma and 1-MeV electrons at differe nt irradiation temperature and the same dose/fluence, is also studied. The radiation-induced degradation becomes significantly smaller for higher expo sure temperatures. It is concluded that the induced radiation defects in th e base and collector regions correlate welt with the device degradation of npn the Si transistors. (C) 2001 Elsevier Science Ltd. All rights reserved.