Radiation-induced charge trapping in Si-MOS capacitors with HfO2/SiO2 gate dielectrics

Abstract

The impact of high dose 60Co gamma-ray irradiation on the oxide traps and interface traps of Au/HfO2-SiO2/Si MOS capacitors is studied by C–V and G–V analysis. The results show that the trapped charges in oxide induce a shift in the C–V curves. The density of the oxide traps increases with the irradiation dose, following a linear relation below 20 kGy(SiO2) and a sublinear relation above that, and accordingly the effective trapping efficiency changes from 18.1% to 1.2%. The distribution of the interface trap density is affected by the irradiation dose. With the increase of the irradiation dose, the shallow energy level interface traps are more susceptible to be generated below 5 kGy(SiO2), but the discrepancy is largely diminished at the high dose of 500 kGy(SiO2). Fermi level pinning is observed at the high doses, and the Fermi level efficiency drops to 75.7% and 65.5% at 100 kGy(SiO2) and 500 kGy(SiO2), respectively.