Golta Khatibi

Abstract:

Small-scaled materials are used in a broad range of applications, from microelectronic systems to medical devices with a continuous trend towards further down-scaling and function integration. The micro-systems are composed of networks of interfaces separating layers of dissimilar materials with a broad range of chemical, physical and mechanical properties. Interfaces have been recognized as potential sites of failure as a result of incompatibility and thermal mismatch in the multilayered materials. Knowledge of fatigue and degradation behavior and understanding the related micro-mechanism of damage with respect to microstructural characteristics of the constituent materials with focus on their interfaces is a prerequisite for design and fabrication of functional and reliable devices. The common practice for reliability assessment and lifetime estimation of electronic devices are accelerated passive and active thermal cycling tests. In the recent years device manufactures are seeking for highly accelerated and realistic reliability assessment methods to respond to the requirements of the rapidly growing technology and keeping up with market demands. In this context, accelerated isothermal fatigue testing has been introduced as an efficient alternative to conventional thermal procedures. A considerable reduction of testing time is achieved by using dedicated high frequency mechanical fatigue testing set-ups in order to replace the thermally induced strains by equivalent mechanical strains. Based on a physics of failure approach, the relevant failure modes in the material interfaces are induced enabling detection of weak sites of the devices in a very short duration of time. Detailed microstructural investigations and failure analysis provide insights into the micro-mechanism of deformation. On the basis of experimental data and numerical methods, the proposed method is used for prediction of lifetime and delamination growth behavior of small scaled multilayered structures. In this talk, exemplary studies on the application of accelerated isothermal mechanical fatigue testing for lifetime assessment of small scaled interconnects and thin multilayered structures are presented and the advantages and limits of the proposed method is briefly discussed.