Expanding Design Possibilities by Blurred Electron Beams during 3D Nanoprinting

Additive, direct-write manufacturing via focused electron beams has evolved into a reliable 3D nanoprinting technology in recent years [1]. Focused electron beam induced deposition (FEBID) bases on the highly localized immobilization of surface adsorbed precursor molecules by focused electron beams and its subsequent processes. As the precursor is injected in gaseous state, this technology has low demands on substrate materials (vacuum and e-beam compatible) and surface morphology (accessible by the electron beam). By the controlled movement of the electron beam, FEBID allows the fabrication of even complex 3D structures with nanoscale features down to the sub-20 nm range [2,3]. While current trends focus on closed and even bulky 3D designs, most 3D-FEBID structures in the past used meshed objects, meaning a combination of differently oriented branches, connected at some points in 3D space according to the final application. While inherently required for some concepts (e.g. 3D nano-plasmonics [4] or magnetic lattices [5]), the small diameters can also limit final applicability due to low mechanical rigidity, thermal or electric conductivities. To optimize those properties without changing the general 3D design type, a controlled way for tuning individual branch diameters would be highly desirable. Following that motivation, we here introduce on-purpose beam blurring for a controlled upward scaling and study the behaviour at different inclination angles. Aside the intended diameter tunability, the study reveals a massive boost in growth efficiencies up to factor 5 due to strongly changed working regime conditions. As a consequence of the latter, unwanted proximal growth beneath overhanging 3D branches is strongly reduced, which increases the reliability of 3D-FEBID. By that, the study expands the design flexibility of this technology by means of tuneable diameters for meshed objects at higher volume growth rates and reduced proximal growth.