Non-destructive high resolution in situ studies of the electromigration in passivated Cu interconnects and integrated circuit conductors by X-ray microscopy

The dynamics during an electromigration process in a passivated Cu interconnect was imaged with 100 nm spatial resolution using an X-ray microscope operating at 4 keV photon energy. A time sequence of images, recorded with the transmission X-ray microscope installed at the ESRF, visualizes the mass transport of Cu at current densities up to 2 x 10(7) A/cm(2) during 2.2 hours of observation. In addition, it was shown that an X-ray microscope permits to image intact integrated circuits by using the X-ray absorption contrast between elements like Si, Cu, Al and W Therefore, transmission X-ray microscopy is a new powerful technique for quantitative analysis of material transport phenomena as well as for failure detection in complete and operational integrated circuits.