Deposition of TiO2 Thin Films using plasma technology for applications in microelectronics

Abstract

Silicon dioxide (SiO2) thin films have been used as gate dielectric from many years in the MOS (Metal-Oxide-Semiconductor) - based integrated elements. Even though they have been thoroughly studied during years, the permanently growing demands of the microelectronic industry limit its application because of the increased density of the circuit elements. For thickness of the gate dielectric thinner than 100 nm the degradation of its qualities, such as break down, current leakage or aging effects become significant. This problem can be solved changing this material by a material with higher dielectric constant. Among the available ones, an excellent candidate is titanium dioxide (TiO2) thin film, since its dielectric constant is higher than 40, it has strong adhesion to the substrate surface and it has a very low interdiffusion coefficient. Recently, thin films of TiO2 have been successfully studied in the Plasmas and Process Laboratory at the Technological Institute of Aeronautics (LPP-ITA). The films have been deposited by means of plasma assisted deposition techniques (IA-PVD), such as conventional magnetron sputtering, using a hollow cathode configuration. It has been observed that, by controlling certain variables of the deposition process, it is possible to control the film structure, degree of crystallinity, surface roughness and, as a consequence, the electrical properties of the films.The present project aims to continue the research work on TiO2 - based thin films emphasizing the electrical characterization of MOS capacitors. By means of C-V and I-V curves, some parameters should be obtained, such as dielectric constant, maximum and minimum capacitance, flat-band voltage, interface deep level trap densities. These parameters will be correlated with the film crystalline structure and morphology, which are directly dependent on the deposition process performance.