Adhesion measurements of Polyimide to silicon nitride for semiconductor component applications

In this study, the adhesion of a 6 µm thick polyimide film to a silicon nitride layer in a thin film stack was investigated using cross-sectional nanoindentation. The significant plasticity in the system, as well as a deviation of the delamination from the expected semicircular buckle shape, commonly observed in such experiments, necessitated the use of an adapted finite element analysis approach for evaluation. For this purpose, intensive investigations using scanning electron microscopy and confocal microscopy were performed to precisely determine the shape and area of the provoked delamination at the interface which consisted of a triangle at either side of the fractured and tilted silicon-wedge. Ultimately the finite element method could be adapted to recreate the behavior of the silicon substrate and the layer during the experiment, allowing the determination of the critical energy release rate for the opened interface. During the simulation, care was taken to remain as true as possible to the established methods to enable a comparison with other systems that exhibit conventional behavior. While the number of experiments where the finite element approach could successfully be implemented is low the obtained results are plausible and robust towards changes in the size of chosen elements for the simulation.