Dielectric properties of TiO2-films reactively sputtered from Ti in an RF magnetron

The dependence of the dielectric constant epsilon(r), chemical composition and crystalline structure of thin titanium oxide films, deposited onto Si substrates, on reactive sputtering conditions has been studied using an RF magnetron operated under different conditions of substrate temperature and O-2 + Ar gas composition. The effect of post-deposition annealing in O-2 was also examined. X-ray photoelectron spectroscopy (XPS) analysis showed the layers were stoichiometric TiO2 and a SiO2 layer existed between Si substrate and TiO2 with a thickness of about 23 Angstrom. Reflection High Energy Electron Diffraction (RHEED) revealed that films were mostly amorphous but some were partially crystallized structures of anatase. Dielectric constants were in the range of 16-52. epsilon(r) was found to increase slightly with increasing O-2 contents in the discharge gas. Increasing the deposition substrate temperature raised epsilon(r). Post-deposition annealing increased epsilon(r) of layers deposited with small O-2 partial pressures and decreased it for layers deposited with large O-2 contents. It also converted amorphous and anatase films to anatase-rutile mixture films with rutile prevailing in layers deposited with 3% O-2. The thickness of the SiO2 intermediate layer increased by about 20%. Copyright (C) 1996 Elsevier Science Ltd