Analysis of TiO2 for microelectronic applications: effect of deposition methods on their electrical properties

Abstract

Metal oxide semiconductor (MOS) device down-scaling is a powerful driving force for the evolution of microelectronics. The downsizing rate of metal oxide semiconductor field effect transistors (MOSFETs) is really marvelous. Silicon dioxide (SiO2) has served as a perfect gate dielectric for the last four decades. Due to physical limitations, leakage current, high interface trap charge it now needs to be replaced with higher permittivity dielectric material. Keeping the motivation for the search of high-k materials, extensive studies have been carried out on several metal oxides, such as ZrO2, Ta2O5, TiO2, Al2O3 and HfO2 for the replacement of SiO2. The high dielectric constant (k) of titanium dioxide (TiO2) will open multifaceted prospects for the use of this material in microelectronic devices. In this paper, a comparative study of various deposition methods for fabrication of thin TiO2 films has been presented. This work uses a combination of simulation results, experimental data and critical analysis of published data. Further, an experiment using sol-gel method has been carried out to deposit thin films of TiO2. It has been characterized and compared with the earlier reported fabrication methods. The X-ray diffraction analyses and Raman spectra indicate the presence of anatase TiO2 phase in the film. The dielectric constant as calculated using capacitance-voltage (C-V) analysis was found to be 23. The refractive index of the film was 2.43. The TiO2 films studied for microelectronic applications and present acceptable properties such as low leakage current density of 1.0×10−5 A/cm at 1 V and band gap of 3.6 eV. The leakage current has been found to be dominant by the Schottky emission at lower electric field, while Flower-Nordheim (F-N) tunneling occurs at higher biasing voltages.