Damage Effect of ALD-Al₂O₃ Based Metal-Oxide-Semiconductor Structures under Gamma-Ray Irradiation

The radiation response of Al₂O₃ on silicon substrate under gamma-rays is studied in this article. The atomic layer deposited Al₂O₃ based metal-oxide-semiconductor structures were irradiated under gamma-ray with the total dose of 1.2 Mrad(Si)/2.5 Mrad(Si)/4 Mrad(Si). The generation, transportation and trapping characteristics of radiation induced charges were studied by using electronic, physical and chemical methods. Firstly, the radiation induced trapped charge density in Al₂O₃ is up to 10¹² cm^-2, with the effective trapping efficiency of 7-20% under irradiation. Secondly, the leakage current through Al₂O₃ changes little with the increase of radiation total dose. Thirdly, oxygen vacancy in Al₂O₃ and O dangling bonds and Al-Si metallic bonds at Al₂O₃/Si interface are dominant radiation induced defects in Al₂O₃/Si system, and the valence band offset between Al₂O₃ and Si is found to decrease after irradiation. From the results we can see that Al₂O₃ is radiation resistant from the aspect of leakage current and crystallization characteristics, but the radiation induced charge trapping and new defects in Al₂O₃/Si structure cannot be ignored. This paper provides a reference for the space application of Al₂O₃ based MOS devices.