Ionizing radiation effects on phosphorus implanted N+ poly gate MOS capacitors with thin gate oxides

Radiation effects on phosphorus implanted N⁺ poly-gate MOS capacitors with a 15-nm oxide grown at different temperatures are investigated. The dependence of the radiation hardness of thin gate oxides on the oxidation temperature as a function of the irradiation bias is investigated, and the results obtained are compared with those of previous studies for both thick and thin oxides. It is shown that the response of the gate oxide depends on the temperature of the phosphorus implant anneal for n⁺ poly implanted gate with an implant energy of 50 keV. A qualitative model is proposed to explain the negative trapping exhibited in the oxides of the capacitors which received an 850°C implant anneal. The model suggests that these electron traps are related to the phosphorus concentration and its electrical activation in the oxide due to the implant anneal temperature