Radiation effects on p+ poly gate MOS structures with thin oxides

The effects of radiation on p⁺ poly gate MOS structures with thin (25-10 nm) oxides are investigated and compared with those on n⁺ poly gate MOS structures using a high-frequency C-V technique. It is found that the characteristics of the oxide charge buildup and the interface state generation are different for n⁺ and p⁺ poly gates. The results indicate that the differences are due to boron atoms penetrating to the gate oxide from the polysilicon gate. On the basis of these observations, a model for the role of boron atoms in the oxide is proposed. In the model, boron atoms in the bulk of the oxide act as electron-hole recombination centers which reduce the number of holes available for trapping, and boron atoms at the interface, which may form B-Si bonds, cause the interface state generation