A Scalable Pathway for Plan-View TEM of 2D Materials and Surface Layers.

Focused ion beam (FIB) microscopy is a powerful tool for preparing site-specific, electron-transparent specimens for atomic-resolution scanning and transmission electron microscopy (S/TEM). Although cross-sectional FIB preparation is routine, it probes too limited a region to provide full details of many two-dimensional/three-dimensional (2D/3D) interfaces over large areas. Plan-view (top-down) S/TEM offers a surface-parallel perspective ideal for probing crystal structure, film continuity, defects, and the alignment of a thin film with a substrate, but standard methods that rely on directly deposited protective coatings can damage delicate layers or obscure critical features. Here, we introduce a scalable method that integrates 3D printing with FIB to produce high-quality, plan-view S/TEM specimens of surface regions of interest. This approach enables tunable protection of multiple areas and preserves few-atom-thick layers, as demonstrated on 2D WS2 flakes. By streamlining plan-view specimen preparation, this method expands access to atomic-resolution S/TEM data on delicate surface layers on various sample types and geometries.