Thin titanium oxide films deposited by e-beam evaporation or by sputtering technique with additional rapid thermal oxidation

Abstract

Titanium oxide has been extensively studied not only in microelectronics, due to its high refractive index, excellent optical constants and high dielectric constant but also in materials science where it was proved to be a biocompatible oxide. In this work we show the structural and electrical characterization results of TiO_x thin films obtained from rapid thermal oxidation of thin titanium films. A comparison between Ti films deposited by e-beam evaporation and sputtering technique with subsequent rapid thermal oxidation with different temperatures on Si wafers is presented. We analyzed the structural characteristics by Ellipsometry, Raman Spectroscopy, Atomic Force Microscopy and X-Ray Difraction identifying the tetragonal crystal structure of the rutile form of TiO₂. Electrical characterizations were obtained through I-V and C-V curves of Al/Si/TiO_x/Al capacitors. Field effect transistors were made in order to analyze I_D×V_DS, g_M×V_GS and I_D×V_GS curves. Electrical characterization of the best sample through the C-V curve showed dielectric constant equal to 8, interface states density in the order of 10^-10eV^-1.cm^-2 and current density of the order of 10^-4/cm². The MOSFET presented Early voltage in the order of kV and output resistance in order of MΩ. This device has threshold voltage equal to 0.30V, leakage current on the order of 10^-8A at VGS equal to -1V and transconductance equal to 12μS, for sample with 4×10^-4cm² gate area.