Total dose response of hafnium oxide based metal-oxide- semiconductor structure under gamma-ray irradiation

The research of the total dose response of high dielectric-constant hafnium oxide under gamma-ray irradiation is important for the anti-irradiation study of the ultra-deep submicron electronic devices in space application. The response of the HfO₂-based Metal Oxide Semiconductor (MOS) structure under various total doses of gamma-ray irradiation is investigated in this article. MOS capacitors which are composed of aluminum electrode, HfO₂ gate dielectric on p-type silicon (Al/HfO2/p- Si) are prepared and tested before and after 60Co gamma-ray irradiation to access the irradiation induced damage in HfO₂/Si system. The surface morphology is obtained by the use of atomic force microscope(AFM), the chemical and physical characteristics are obtained using X-ray diffractometer (XRD) and X-ray photoelectron spectrometer(XPS), and the charge trapping characteristic of HfO₂ film is calculated from the current-voltage(CV) curve by the semiconductor parameter testing. Crystallized HfO2, SiO₂ and HfSiO₄ are detected from the XRD spectrum and the crystallinity and grain size are found to decrease with the increase of gamma-ray total dose. Oxygen vacancy is found to increase after irradiation and it dominates the oxide charge trapping in the HfO₂/Si system. Schottky emission is found to be the charge transport mechanism from the currentvoltage curve at room temperature, and the barrier height of HfO₂/Si interface is found to decrease with the increase of irradiation. Irradiation induced defects would lower the HfO₂/Si interface barrier height and then give rise to the leakage current, this will consequently lead to the failure of HfO₂ film and corresponding MOS structures.