Thermal Stress Behavior of Micro- and Nano-Size Aluminum Films


In-situ observation of thermal stresses in thin films deposited on silicon substrate was made by X-ray andsynchrotron radiation. Specimens prepared in this experiment were micro- and nano-size thin aluminum films with andwithout passivation film. The thickness of the film was 1 micrometer for micro-size films and 10, 20 and 50 nanometerfor nano-size films. The stress measurement in micro-size films was made by X-ray radiation whereas the measurementof nano-size films was made by synchrotron radiation. Residual stress measurement revealed tensile stresses in all as-depositedfilms. Thermal stresses were measured in a series of heating- and cooling-stage. Thermal stress behavior ofmicro-size films revealed hysteresis loop during a heating and cooling process. The width of a hysteresis loop was largerin passivated film that unpassivated film. No hysteresis loops were observed in nano-size films with Si02 passivation.Strengthning mechanism in thin films was discussed on a passivation film and a film thickness.Keywords: Thermal stress, in-situ observation, aluminum film. X-ray measurement, synchrotron radiation. T. Hanabusal, M. Nishida2, K. Kusaka3IInstitute of Technology and Science, the University ofTokushima, Tokushima, Japan2Department of Mechanical Engineering, Kobe City Collage of Technology, Kobe, Japan3Institute ofTeclmology and Science, the University ofTokushima, Tokushima, Japan