3D Nanoprinting with Electrons - From Meshes to Closed Structures

Additive manufacturing of 3-dimensional objects on the nanoscale is a very demanding task. Among the few capable techniques, 3D nanoprinting via Focused Electron Beam Induced Deposition (3D-FEBID) is a highly promising candidate due to its additive direct-write capabilities with feature sizes below 100 nm on a regular basis and even below 20 nm under optimized conditions. The working principle relies on the localized immobilization of surface adsorbed precursor molecules, injected in the vacuum chamber in gaseous states. Consequently, the demands on substrate materials and in particular surface morphologies are very low, turning 3D-FEBID into a powerful and flexible 3D nanoprinting technology. In the past, however, most fabricated structures were meshed, meaning a combination of differently oriented, individual nanowires, which were connected at specific points in 3D space according to the target application. To leverage this technology to the next level, we here report about the progress to expand 3D-FEBID capabilities from mesh-like towards closed structures.The main challenge, we had to face is based on local beam heating and its implications on local growth rates. While well understood in meshed structures, closed objects revealed additional dependencies on the dimensions of built objects and the XY pixel position within the structures. Furthermore, electron trajectories are more complex in closed objects, introducing additional proximity effects.To tackle that problem, we combined finite element simulations with 3D-FEBID experiments and developed a python-based compensation tool, capable of stabilizing the growth in each patterning plane by pre-determined parameter adaptions. The gained insight allowed further expansion, now being applicable for different element-widths and -heights, as demonstrated by more advanced structures. By that, the new model crucially expands FEBID-based 3D nanoprinting by opening up design possibilities for closed and consequently mixed objects for novel applications in various fields of research and development.