Morphological selections and dynamical evolutions of buckling patterns in SiAlNx films: From straight-sided to telephone cord or bubble structures

We report on the morphological selections and dynamical evolutions of buckling patterns in annealed SiAlNx films deposited on 6 mm thick glass substrates. Various buckle modes, including straight-sided, bubble (or varicose) and telephone cord structures, are found to coexist in the same sample. The straight-sided mode appears only when the buckle width is less than a critical value (about 50 μm in the experiment). When the buckle width increases, the straight-sided buckle destabilizes and evolves into the telephone cord structure gradually. If the buckling patterns form ridge cracks, the original straight-sided blisters and telephone cord buckles with smaller widths invariably evolve into the bubble mode, whereas the telephone cord buckles with larger widths can keep the antisymmetric mode. These buckle modes and their dynamical evolutions are discussed based on the stability diagram of unilateral buckling patterns.