Residual Stress and Buckling Patterns of Free-standing Yttria-stabilized-zirconia Membranes Fabricated by Pulsed Laser Deposition

The residual stress and buckling patterns of free-standing 8?mol.% yttria-stabilized-zirconia (8YSZ) membranes prepared by pulsed laser deposition and microfabrication techniques on silicon substrates are investigated by wafer curvature, light microscopy, white light interferometry, and nanoindentation. The 300?nm thin 8YSZ membranes (390?mu m?x?390?mu m) deposited at 25?degrees C are almost flat after free-etching, whereas deposition at 700?degrees C yields strongly buckled membranes with a compressive stress of 1,100?+/-?150?MPa and an out-of-plane-displacement of 6.5?mu m. These latter membranes are mechanically stable during thermal cycling up to 500?degrees C. Numerical simulations of the buckling shape using the RayleighRitz-method and a Young's modulus of 200?GPa are in good agreement with the experimental data. The simulated buckling patterns are used to extract the local stress distribution within the free-standing membrane which consists of tensile and compressive stress regions that are below the failure stresses. This is important regarding the application in, e.g., microsolid oxide fuel cell membranes which must be thermomechanically stable during microfabrication and device operation.