Modulation of microstructure and interface properties of co-sputter derived Hf_(1−x)Ti_xO_2 thin films with various Ti content

摘要

Hf_(1−x)Ti_xO_2 dielectric thin films were deposited on Si (100) substrates by RF reactive co-sputtering with the variation in RF power of Ti target. The compositional, morphological, structural and optical properties of Hf_(1−x)Ti_xO_2 films with various Ti concentration were systematically investigated by X-ray photoelectron spectroscopy (XPS), Field emmission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and Raman spectroscopy techniques respectively. The electrical properties of the co-sputtered thin films were studied by capacitance-voltage and current density-voltage measurements. The XRD study has shown the enhancement in the the crystalline property of Hf_(1−x)Ti_xO_2 film up to 60 W of Ti target power and amorphous like behaviour was observed for higher RF power. The Ti content in Hf_(1−x)Ti_xO_2 was calculated from the XPS measurements, where the Ti content was found to be increased with rise in RF power. FESEM micrographs depict the increase in grain size upto the RF power 60 W. The Raman spectrum of the Hf_(1−x)Ti_xO_2 film has shown that the major generated phase was titanium-substituted monoclinic phase of HfO_2. The flatband voltage (V_(fb)) and oxide charge density (Q_(ox)) were extracted from the high frequency (1 MHz) C-V curve. The D_(it) has a minimum value for the film deposited at 60 W RF power of Ti target. The leakage current density of the Hf_(1−x)Ti_xO_2 films was found to be minimum for the RF power 60 W.