Thin-Film Engineering of Mechanical Fragmentation Properties of Atomic-Layer-Deposited Metal Oxides

Mechanical fracture properties were studied for the common atomic-layer-deposited Al(2)O(3), ZnO, TiO(2), ZrO(2), and Y(2)O(3) thin films, and selected multilayer combinations via uniaxial tensile testing and Weibull statistics. The crack onset strains and interfacial shear strains were studied, and for crack onset strain, TiO(2)/Al(2)O(3) and ZrO(2)/Al(2)O(3) bilayer films exhibited the highest values. The films adhered well to the polyimide carrier substrates, as delamination of the films was not observed. For Al(2)O(3) films, higher deposition temperatures resulted in higher crack onset strain and cohesive strain values, which was explained by the temperature dependence of the residual strain. Doping Y(2)O(3) with Al or nanolaminating it with Al(2)O(3) enabled control over the crystal size of Y(2)O(3), and provided us with means for improving the mechanical properties of the Y(2)O(3) films. Tensile fracture toughness and fracture energy are reported for Al(2)O(3) films grown at 135 °C, 155 °C, and 220 °C. We present thin-film engineering via multilayering and residual-strain control in order to tailor the mechanical properties of thin-film systems for applications requiring mechanical stretchability and flexibility.