Fracture mechanics of thin film systems on the sub-micron scale

Novel design of microelectronic components creates new issues concerning their reliability. Internal mechanical loading, e.g. from residual stresses, or external loading when the component is assembled into a microelectronic device, can cause failure via cracking or delamination. In this work, finite element simulations of micro-beam bending experiments for testing the fracture behavior of thin film metal composites deposited on a silicon substrate are presented. Due to the lattice mismatch between the materials, residual stresses are generated. Calculating the magnitude and distribution of these stresses is very important, as they add to the stresses produced by the external loads. Consequently, a stress free setting will behave differently compared to a structure with residual stresses. Additionally, crack propagation is affected by an interface to a material with different characteristics. In what follows, the variation of typical fracture parameters will be shown, depending on the residual stresses in the composite and on the crack position relative to the interface.