Expanding 3D Nano-Printing Performance by Blurring the Electron Beam

FEBID is a mask-less direct-write fabrication process where surface adsorbed precursor molecules are dissociated and thereby immobilized upon irradiation with a focused electron beam. Aside from the additive character with minimal demands on the substrate materials and morphologies, this technology allows the fabrication of freestanding, 3-dimensional architectures with feature sizes down to the sub-20 nm range. As FEBID based 3D nanoprinting[1] is realized by the slow lateral movement of the electron beam, the design flexibility is very high, which opens up entirely new possibilities for e.g. optical metamaterials, plasmonic structures and advanced scanning probe microscopy tips[2]. The long term aim of this work is to tune the 3D-FEBID process in a way, which allows the deposition of functional electromagnetic helices, which require long, freestanding and shallow inclined segments. While beneficial for other applications such as 3D plasmonics, the small nanowire diameters, obtained by standard 3D-FEBID conditions, entail highly growth instabilities due to their high thermal resistance, which lead to heating issues in the beam impact regions. Based on previous studies with defocused electron-beams[3], we studied the controlled introduction of a beam blur for 3D-FEBID. Our results reveal, that the introduction of a defocused e-beam can stabilize the spatial growth in 3D space (precision), while growth rates strongly increase (efficiency) and all unwanted artifacts are minimized (co-deposits and / or structural collapse). At the same time, blurred beams not only allow an on-purpose tuning of branch diameters but also can be used for shifting the height/width aspect ratio within certain ranges. By that, this study lies the foundation for the originally aimed fabrication of functional electromagnetic helices, which will be in focus in near future