Nano-additively manufactured gold thin films with high adhesion and near-bulk electrical resistivity via jet-assisted, nanoparticle-dominated, room-temperature microsputtering

Microsputtering is a novel additive manufacturing technique that takes a completely new approach to the printing of conductors, directly writing on an arbitrary substrate with the use of a microplasma, i.e., a plasma generated at atmospheric pressure by an arrangement of electrodes with millimeter-scale or smaller spacing. Conductors deposited via microsputtering promise significantly improved electrical conductivity over traditional extrusion ink-based methods. This study investigates, via a design of experiments, the deposits created by a 3D printer-compatible write head that encompasses an atmospheric-pressure gold microsputterer with strong coaxial gas flow. In addition to attaining 1 nm/s deposition rates—on par with traditional (i.e., vacuum) sputtering, the microplasma sputterer creates ~100 nm-thick gold films with near-bulk electrical resistivity (down to 2.9 µΩ cm, i.e., 120% the bulk value) and excellent adhesion—without employing an adhesion layer, annealing, or any other pre/post-processing steps. It is concluded that the strong gas flow promotes the formation of nanoparticles in the plasma plume out of the originally microsputtered gold atoms, which in turn, deposit and create films with excellent adhesion and conductivity. [Display omitted] •A high-coaxial gas flow microsputterer is investigated to print gold thin films.•Strong gas flow helps create nanoparticles in the plasma, making high-quality films.•3D-printer compatible write head deposition rate is 1 nm/s—akin to vacuum sputtering.•~100 nm-thick gold films have near-bulk electrical resistivity (2.9 μΩ cm)•Gold thin films show excellent adhesion without using an adhesion layer or annealing