@article{ZschechLechowskiKuturkovaetal.2024, author = {Zschech, Ehrenfried and Lechowski, Bartlomiej and Kuturkova, Kristina and Panchenko, Luliana and Kr{\"u}ger, Peter and Clausner, Andr{\´e}}, title = {Laboratory X-ray microscopy of 3D nanostructures in the hard X-ray regime enabled by a combination of multilayer X-ray optics}, series = {Nanomaterials}, volume = {14}, journal = {Nanomaterials}, number = {2}, publisher = {MDPI}, address = {Basel}, issn = {2079-4991}, doi = {10.3390/nano14020233}, year = {2024}, abstract = {High-resolution imaging of buried metal interconnect structures in advanced microelectronic products with full-field X-ray microscopy is demonstrated in the hard X-ray regime, i.e., at photon energies > 10 keV. The combination of two multilayer optics—a side-by-side Montel (or nested Kirkpatrick-Baez) condenser optic and a high aspect-ratio multilayer Laue lens—results in an asymmetric optical path in the transmission X-ray microscope. This optics arrangement allows the imaging of 3D nanostructures in opaque objects at a photon energy of 24.2 keV (In-Kα X-ray line). Using a Siemens star test pattern with a minimal feature size of 150 nm, it was proven that features < 150 nm can be resolved. In-Kα radiation is generated from a Ga-In alloy target using a laboratory X-ray source that employs the liquid-metal-jet technology. Since the penetration depth of X-rays into the samples is significantly larger compared to 8 keV photons used in state-of-the-art laboratory X-ray microscopes (Cu-Kα radiation), 3D-nanopattered materials and structures can be imaged nondestructively in mm to cm thick samples. This means that destructive de-processing, thinning or cross-sectioning of the samples are not needed for the visualization of interconnect structures in microelectronic products manufactured using advanced packaging technologies. The application of laboratory transmission X-ray microscopy in the hard X-ray regime is demonstrated for Cu/Cu6Sn5/Cu microbump interconnects fabricated using solid-liquid interdiffusion (SLID) bonding.}, subject = {X-ray microscopy; High-resolution radiography; Nanostructure; Advanced packaging; R{\"o}ntgenmikroskopie; Hochaufl{\"o}sende Radiographie; Nanostruktur; Erweiterte Verpackung; Nanostruktur; R{\"o}ntgenmikroskopie; Radiographie}, language = {en} }