Effects of physical growth conditions on the structural and optical properties of sputtered grown thin HfO 2 films

Abstract

HfO 2 thin films were prepared by reactive DC magnetron sputtering technique on (100) p-Si substrate. The effects of O 2/Ar ratio, substrate temperature, sputtering power on the structural properties of HfO 2 grown films were studied by Spectroscopic Ellipsometer (SE), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectrum, and X-ray photoelectron spectroscopy (XPS) depth profiling techniques. The results show that the formation of a SiO x suboxide layer at the HfO 2/Si interface is unavoidable. The HfO 2 thickness and suboxide formation are highly affected by the growth parameters such as sputtering power, O 2/Ar gas ratio during sputtering, and substrate temperature. XRD spectra show that the deposited films have (111) monoclinic phase of HfO 2, which is also supported by FTIR spectra. XPS depth profiling spectra shows that highly reactive sputtered Hf atoms consume some of the oxygen atoms from the underlying SiO 2 to form HfO 2, leaving Si–Si bonds behind.