Radiation Induced Leakage Current of HfO2-based MOS Capacitors under 60Co Gamma Ray

Hafnium oxide (HfO₂) is the most promising high-k gate dielectric used in microelectronic industry, the study of its' response to the radiation from space and other possible nuclear environment is of great significance for the reliability and lifetime improvement of electronic devices. Hafnium oxide is widely used in novel metal-oxide-semiconductor (MOS) devices, which are the most vulnerable devices under ionic radiation such as gamma-ray and X-ray. The total dose response of hafnium oxide based MOS structure under ⁶⁰Co gamma-ray irradiation is studied in this article, and radiation induced leakage current characteristics of HfO₂ are summarized and the degradation mechanism is discussed. HfO₂ films with different thickness are prepared using atomic layer deposition (ALD) method, and Al/HfO₂/Si MOS structures are also prepared by evaporating aluminum onto the top of HfO₂ film in order to form a metal electrode to facilitate the following electrical measurements. Current-voltage test is applied to study the leakage current and charge transport mechanism through HfO₂. It shows that the leakage current increases sharply after gamma-ray irradiation; the barrier height on the HfO₂/Si interface and the trap depth inner the HfO₂ film gets lower and lower with the increase of radiation total dose.