Abstract
A method that controls the residual stress in crystalline films was proposed by vibrating the substrate using a piezo actuator [A. Matsumuro et al., J. Japan Soc. Prec. Eng., Vol.70, No.4, (2004)533]. The mechanism behind the control of the residual stress has not been clarified to date. Here, grain size measurements of the films were taken by XRD, the microstructure by SEM, TEM and AFM and the density of the film by fluorescent X-ray spectroscopy. Independent of substrate vibration, both Ti and TiN films had columnar structure when being prepared by the evaporation technique of electron beam heating, but compressive residual stress turned to tensile upon applying substrate vibration. The grain size decreased and the gap between adjacent crystals at the point of coalescence increased with an increase of vibration amplitude. This is because the decrease in grain size stimulates the development of tensile stress caused by crystallite coalescence while an increasing gap in the columnar structure causes contraction in the film enhancing tensile stress.
