In-Situ Impedance Spectroscopy Of A Plasma-Semiconductor Thin Film System During Reactive Sputter Deposition

We present a comparatively simple-to-apply in situ diagnostic suitable for determining the dielectric properties of nonconducting and semi-conducting thin films during plasma-aided deposition. The method is based on measurement of the impedance spectrum of a system plasma-film within the kilohertz range of frequencies, i.e., without the need of special equipment. Total film capacitance, resistance, and the loss factor tan delta can be estimated in situ from the measured impedance spectra. Provided that the film thickness is known, the dielectric and electrical properties of the deposited films, such as relative permittivity epsilon(r) and conductivity sigma, can be estimated as well. The applicability of the developed method is demonstrated on Fe2O3 and TiO2 thin films during deposition in a low-pressure low-temperature plasma-jet system and on a TiO2 thin film during deposition in a planar magnetron system. The experimentally obtained dielectric properties are compared with data from the literature.