Structure, surface morphology and electrical properties of evaporated Ni thin films: Effect of substrates, thickness and Cu underlayer

Abstract

Series of Ni thin films have been deposited by thermal evaporation onto glass, Si(111), Cu, mica and Al2O3 substrates with and without a Cu underlayer. The Ni thicknesses, t, are in the 4 to 163nm range. The Cu underlayer has also been evaporated with a Cu thickness equal to 27, 52 and 90nm. The effects of substrate, the Ni thickness and the Cu underlayer on the structural and electrical properties of Ni are investigated. Rutherford Backscattering Spectroscopy was used to probe the Ni/Substrate and Ni–Cu underlayer interfaces and to measure both Ni and Cu thicknesses. The texture, the strain and the grain size values were derived from X-ray diffraction experiments. The surface morphology is studied by means of a Scanning Electron Microscope. The electrical resistivity is measured by the four point probe. The Ni films grow with the <111> texture on all substrates. The Ni grain sizes D increase with increasing thickness for the glass, Si and mica substrates and decrease for the Cu one. The strain ε is positive for low thickness, decreases in magnitude and becomes negative as t increases. With the Cu underlayer, the growth mode goes through two phases: first, the stress (grain size) increases (decreases) up to a critical thickness tCr, then stress is relieved and grain size increases. All these results will be discussed and correlated.