Spatially-Resolved Layer, Interface and Dopant Profiling Using Tabletop Coherent EUV Beams

Next-generation devices, nanomaterials, quantum and magnetic materials necessarily have increasingly complex layers, dopants and 3D structures. As a result, non-destructive techniques that can image through visibly opaque layers with sensitivity to layer and interfacial composition are critical for synthesizing and optimizing these systems. We present a tabletop complex-imaging reflectometer illuminated by coherent high harmonic extreme ultraviolet (EUV) beams. Unlike most reflectometers that transversely average quantities such as film thicknesses over the sample, our reflectometer can attain diffraction-limited spatial resolution with high sensitivity to material composition by using coherent diffractive imaging (CDI). Our complex imaging reflectometer uses grazing-incidence CDI to generate high-resolution, high-fidelity phase and amplitude images of a sample at many incidence angles. The phase images are extremely sensitive to composition, allowing us to extract a 3D map of the sample. We demonstrate the ability to very sensitively probe diffusion at buried interfaces, layer thickness and dopant profiles in a non-destructive and spatially resolved manner, distinguishing our technique from others such as SIMS, Auger sputtering, or electron imaging.