Damage effect of hafnium oxide gate dielectric based metal–oxide–semiconductor structure under gamma-ray irradiation

The radiation response of HfO2 films on a silicon substrate under gamma rays is studied in this article. HfO2 films with the thickness of 12.8 and 4.3 nm are prepared on a p-type silicon substrate by using the atomic layer deposition method, and the HfO2/Si MOS structure is irradiated under gamma rays with the total dose of 1.2/2.5/4 Mrad. The generation, transportation, and trapping characteristics of radiation induced charges are studied by using electronic, physical, and chemical methods. First, radiation induced oxide and interface trapped charge densities are found to be up to 1012 cm−2, and oxygen vacancies in HfO2 and Hf–Si metallic bonds at the HfO2/Si interface are dominant defects in the HfO2/Si system. Second, the leakage current through HfO2 increases with the increase in the radiation total dose and the crystallinity also increases after a large total dose of irradiation. Third, the valence band offset between HfO2 and Si is found to decrease slightly after irradiation. From the results, we can see that HfO2 is radiation resistant from the aspect of charge trapping even under a very large total dose of radiation, but the radiation induced leakage current and crystal structure change in the HfO2 film cannot be ignored. This provides a reference for microelectronic devices working in the space environment.