Ultrathin metallic films are important functional materials for optical and microelectronic devices. Dedicated characterization with high spatial resolution and sufficient field of view is key to the understanding of the relation between microstructure and optical and electrical properties of such thin films. Here, we have applied on-axis transmission Kikuchi diffraction (TKD) and scanning precession electron diffraction (SPED) to study the microstructure of 10 nm thick polycrystalline gold films. The study compares the results obtained from the same specimen region by the two techniques and provides insights on the limits of each diffraction technique. We compare the physical spatial resolution of on-axis TKD and SPED and discuss challenges due to the larger probe size in scanning electron microscopy (SEM). Moreover, we present an improvement for the physical spatial resolution (PSR) of on-axis TKD through acquisition in immersion mode. We show how this method extends the capabilities of SEM-based microstructure characterization of ultrathin films and achieve PSR comparable to semi-automated SPED.

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