Controlled Bending of 3D-Nanoprinted Structuresvia Electron Beam Curing

Additive manufacturing via Focused Electron Beam Induced Deposition (FEBID) is an increasingly relevant techniquefor depositing high-fidelity architectures on the nanoscale. While most such structures in the past were of a meshednature [1], recent developments towards building closed (sheet-like) elements have opened up the field for a wholenew range of possibilities [2]. In a next step we now explored post-growth electron beam curing (EBC) [3], where thestructures are locally irradiated without precursor gas present. This process impacts the inner structure and the overallvolume of exposed elements and, if only applied partially, enables controlled deformation. We therefore performedexperimental series, analyzed via SEM and TEM and complemented by Monte Carlo Simulations to exploreand identify ideal parameters for smooth, stable and reproducible morphological bending. Figures 1a and 1b show avertical wall with a width of 1 μm and a height of 2 μm that was bent via electron beam irradiation within a definedarea across the structure. Figure 1c shows a more complex (originally straight) screw element where two areas havebeen exposed to EBC, clearly illustrating the bending effect towards the incidence direction. We attribute this“forward” bending to smaller interaction volumes of the incoming electrons compared to the wall thickness mainlyinfluencing the front part of the elements in comparison with the back side. We evaluated the impact for a variety ofparameters, such as voltage, point pitch, dwell time, overall dose and bending angle to achieve controlled and reproducibleresults. The expansion to more complex EBC pattern leads furthermore to more complex bending as will bepresented as well. We thereby extended the post-growth treatment possibilities of FEBID, showing the flexibility ofEBC for various applications in research and development, some of which clearly go beyond the capabilities of sole3D FEBID (e.g. spatially tuned mechanics).