In this paper we address the degradation of oxide reliability after annealing the phosphorusdoped polysilicon of MOS structures. The oxide reliability was studied in terms of X-ray radiation sensitivity as well as breakdown characteristics.
We found that annealing the polysilicon increased the radiation sensitivity of the gate oxide. We believe that this increase is a result of the phosphorus out-diffusion from the polysilicon into the oxide and a result of the creation of phosphorus related traps in the oxide bulk. We also found that the oxide charge to breakdown (Qbd ) degradation correlates well with the density of the phosphorus in the oxide.