High resolution x-ray tomography with applications in biology and materials science

With the new tomography setup developed for the x-ray microscope XM-1 installed at the Advanced Light Source, tomography of immunolabelled frozen-hydrated cells to detect protein distributions inside of cells was performed. The distribution of the nuclear protein, male specific lethal 1 (MSL-1) in the Drosophila melanogaster cell was studied. Another application field for high resolution tomography which is of fundamental interest in materials science is electromigration in advanced copper interconnects. In this work, quantitative time-resolved x-ray microscopy mass transport studies of the early stages of electromigration in an inlaid Cu line/via structure were performed with 40 nm spatial resolution at 1.8 keV photon energy. Correlation of the real time x-ray microscopy images with post mortem high voltage electron micrographs of the sample shows that the void nucleation occurs at the site of grain boundaries in Cu and that the voids migrate along these grain boundaries during electromigration. To provide 3D information about the exact location (bulk or interface) of void nucleation and migration during an EM experiment, as well as to measure quantitatively the mass transport in the volume, future experiments must be based on time-resolved x-ray tomography.