Using Electron Beam Curing (EBC) for the Controlled Bending of 3D-Nanoprinted FEBID Structures

Additive manufacturing via Focused Electron Beam Induced Deposition (FEBID) is anincreasingly relevant technique for depositing high-fidelity architectures on the nanoscale.While most such structures in the past were of a meshed nature [1], recent developmentstowards building closed (sheet-like) elements have opened up the field for a whole newrange of possibilities [2]. In a next step we now explored post-growth electron beam curing(EBC) [3], where the structures are locally irradiated without precursor gas present. Thisprocess impacts the inner structure and the overall volume of exposed elements and, if onlyapplied partially, enables controlled deformation. We therefore performed experimentalseries, 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 a vertical wall with a width of 1 μm and a height of 2 μm that wasbent via electron beam irradiation within a defined area across the structure. Figure 1cshows a more complex (originally straight) screw element where two areas have beenexposed to EBC, clearly illustrating the bending effect towards the incidence direction. Weattribute this “forward” bending to smaller interaction volumes of the incoming electronscompared to the wall thickness, mainly influencing the front part of the elements incomparison with the back side. We evaluated the impact for a variety of parameters, suchas voltage, point pitch, dwell time, overall dose and beam incidence angle to achievecontrolled and reproducible results. The expansion to more complex EBC patterns leadsfurthermore to more sophisticated bending as will be presented as well (see Fig. 2). Wethereby extended the post-growth treatment possibilities of FEBID, showing the flexibility ofEBC for various applications in research and development, some of which clearly go beyondthe capabilities of sole 3D FEBID (e.g. spatially tuned mechanics).