In-situ metrology and testing of nanotwinned copper pillars for potential air gap applications

We have performed in-situ nanocompression testing in a transmission electron microscope (TEM) of copper pillars having dimensions of the same order of typical via and line structures used in the semiconductor industry. We show direct evidence that twin boundaries can withstand extensive plastic deformation and still retain their structure when compared to regular grain boundaries. Through real-time TEM observations we have verified the deformation mechanisms of twin boundaries predicted by molecular dynamic (MD) simulations. Our quantitative in-situ stress measurements are also in close agreement with those reported by MD and energetics based calculations.