Survey of the theory and experimental measurements of residual stress in Pd thin film

Abstract

Different thicknesses of Pd thin film were deposited over SrTiO3 by electron beam physical vapor deposition. Residual stress for each thickness of Pd film was computed by applying conventional x-ray diffraction method and taking into account Poisson’s ratio and elastic module measured by Nanoindentation. We observed that Pd stress variation at 300 °C substrate temperature obeys the trend of type II metals with high adatom mobility. Several models alluded in the literature were compared to the stress variation of the Pd films. Two models, namely; Freund–Chason and Guisbiers–Van Overschelde–Wautelet were found to be in agreement with the experimental results in that for the thicknesses less than 30 nm, Guisbiers–Van Overschelde–Wautelet is dominant but for higher than 30 nm, variation in stress follows Freund–Chason model. Therefore, the thickness around 30 nm could be considered as coalescence thickness. Surprisingly, this transition thickness is the same thickness that Guisbiers–Van Overschelde–Wautelet and Freund–Chason models intersect. Negligible residual stress and high conductance of 30 nm Pd thin film reveal the importance of this transition thickness in microelectronic technology.