Thin Film Interface Fracture Properties at Scales Relevant to Microelectronics

Nowadays, one of the trends in microelectronic packaging is to integrate multi-functional systems into one package, resulting in more applications of highly dissimilar materials in the form of laminated thin films or composite structures. As a consequence, the number of interfaces increases. Often, the interface between these dissimilar materials is where the failure is most likely to occur especially when the packaged devices are subjected to the thermo-mechanical loading. Prediction of interface delamination is typically done using the critical energy release rate. However, the critical value is dependent on mode mixity. This paper describes our efforts on interface characterization as a function of mode mixity. A new test setup is designed for mixed mode bending testing. It allows for measuring the stable crack growth as the function of mode mixity. The crack length, necessary for calculation of the energy release rate is measured by means of an optical microscope. Finite element simulation is used to interpret the experimental results and thus to establish the critical energy release rates and mode mixities.