High fluence 1.8 MeV proton irradiation effects on n-type MOS capacitors

MOS capacitors with 7 nm SiO2 dielectrics and n-doped Si substrate were irradiated by 1.8 MeV protons with fluences ranging from 1012 to 5 × 1013 cm−2 which correspond to the typical LHC fluence range. No significant increase in gate oxide leakage current was detected. A decrease of the capacitance was observed in the accumulation regime. This effect is explained by an increase of the substrate resistivity caused by displacement damage.

► Thin MOS capacitors high fluence 1.8 MeV proton irradiation effects are investigated.
► C–V curves of 7 nm n-type MOS capacitors are measured before and after irradiation.
► A decrease of accumulation regime capacitance is shown at fluences up to 5 × 1012 cm−2.
► It is the first time that such device effect is observed within the LHC fluence range.
► This effect is mainly due to a proton-induced increase of the substrate resistivity.