Spatial and kinetic evolutions of telephone cord buckles

We report on the spatial and kinetic evolutions of telephone cord buckles existing in SiAlNx films sputtered on 6 mm thick glass substrates. The experiment shows that the telephone cord buckles propagate from the film edges to the central regions after annealing. During propagation, the already formed buckle undergoes a reorganization process and it can expand in the longitudinal, transverse and normal directions simultaneously. As a result, various morphological parameters (including wavelength, amplitude, width, maximum deflection etc.) evolve obviously both in spatial scale and time scale, which have been measured and analyzed in detail. The internal stress of the film is also evaluated based on the continuum elastic theory.