Baking-temperature-modulated optical and electrical properties of HfTiOx gate dielectrics via sol-gel method

Abstract Deposition of HfTiO x gate dielectric films on n-type Si and quartz substrates by sol–gel technique has been performed and the optical, electrical characteristics of the as-deposited HfTiO x thin films as a function of baking temperature have been investigated. The components and optical properties of HfTiO x thin films related to baking temperature are investigated by energy dispersive spectrometer (EDS), ultraviolet–visible spectroscopy (UV–Vis), and spectroscopy ellipsometry (SE). By measurement of EDS, the Hf/Ti molar ratio of HfTiO x thin films is calculated to be about 1:1.20 at all baking temperature. The increase in band gap is observed with the increase of baking temperature. Additionally, the electrical properties based on Al/Si/HfTiO x /Al capacitor are analyzed by means of the high frequency capacitance-voltage ( C-V ) and the leakage current density-voltage ( J-V ) characteristics. Results have shown that 200 °C-baked sample demonstrates good electrical performance, including larger dielectric constant of 23.31 and lower leakage current density of 5.12 × 10 −5 A/cm 2 at the gate voltage of 1 V. Additionally, the leakage current conduction mechanisms as functions of baking temperatures are also discussed systematically.