Ligand Co-Deposition in Focused Electron Beam Induced Nanoprinting: A Predictive Composition Model

Recent advances in nanotechnology have created the need to manufacture 3D nanostructures with controlled material composition. Focused Electron Beam Induced Deposition (FEBID) is a nanoprinting technique offering highest spatial resolution combined with the ability to directly 3D-print almost any shape. It relies on local electron-induced dissociation of metal-ligand organometallic molecules adsorbed onto a substrate. So far FEBID continuum modeling involves the surface kinetics of precursor molecules during electron irradiation and succeeds in the prediction of nanoprint shape and growth rate and forms nowadays the basis of software for 3D nano-printing of nanostructures. Here, the model is expanded to the surface kinetics of detached ligands. Involving their dissociation and desorption behavior allows to predict trends in the metallic composition of the nanoprinted material and to define desirable nanoprint process windows as function of electron exposure time and flux. The theoretical foundations of the model is presented, validate it experimentally for chromium and silver precursors, compare calculated values with literature data for various precursors, and discuss its potential to design new experiments. This contribution enhances the understanding of FEBID dynamics and provides a versatile framework for predictive FEBID material nano-printing.