Radiation Induced Si–SiO2 Interface States and Positive Charge Buildup of MOS Capacitors Annealed in Nitrogen and in Hydrogen After Metalization

Abstract

The density of Si–SiO2 interface states (ΔDit) and the density of trapped oxide charges (ΔNot) generated by Co-60 gamma ray irradiation are examined for MOS capacitors with post metalization annealing (PMA) in hydrogen and in nitrogen. A good correlation between |ΔVmg-ΔVFB| and \\int Dit dE is found, and it verifies that the charging at the interface states affects the estimation of ΔNot from the VFB shift. The radiation hardness of the MOS structure is sensitive to annealing conditions. PMA is effective in decreasing ΔDit and ΔNot. The PMA effect is discussed in terms of weak bond and interstitial hydrogen atoms. Moreover annealing after irradiation is found to be effective in recovery of radiation damage on MOS devices.