Effect of excess hafnium on HfO2 crystallization temperature and leakage current behavior of HfO2/Si metal-oxide-semiconductor devices

Abstract

This article reports the role of excess Hf on the crystallization temperature of thin HfO2 film and leakage current behavior of Hf-rich HfO2/Si metal-oxide-semiconductor (MOS) devices. The HfO2 thin-films deposited by the radio-frequency sputtering system with different Ar:O2 gas mixtures are studied by differential scanning calorimetry. The crystallization temperature of Hf-rich HfO2 film is found to be lower than that of the HfO2 film. The grazing incidence x-ray diffraction studies also confirm the above observation. X-ray photoelectron spectroscopy study further indicates the presence of excess Hf in the oxide film. Enhanced structural relaxation in the presence of excess Hf in HfO2 film releases energy, already stored within the film during deposition, which is responsible for lowering of crystallization temperature. The gate leakage current characteristics are deteriorated in the presence of excess Hf in the HfO2/Si MOS device.