Microscale Metal Additive Manufacturing by Solid‐State Impact Bonding of Shaped Thin Films

Abstract

The deposition of device-grade inorganic materials is one key challenge towardthe implementation of additive manufacturing (AM) in microfabrication, andto that end, a broad range of physico-chemical principles has been exploredfor 3D fabrication with micro- and nanoscale resolution. Yet, for metals,a process that achieves material quality rivalling that of established thin-filmdeposition methods, and at the same time, has the potential to combinehigh throughput production with a broad palette of processable materials, isstill lacking. Here, the kinetic, solid-state bonding of metal thin films for theadditive assembly of high-purity, high-density metals with micrometer-scaleprecision is introduced. Indirect laser ablation accelerates micrometer-thickgold films to hundreds of meters per second without their heating or ablation.Their subsequent impact on the substrate above a critical velocity forms apermanent, metallic bond in the solid state. Stacked layers are of high density(>99%). By defining thin-film layers with established lithographic methodsprior to launch, a variable feature size (2–50 µm), arbitrary shape of bondedlayers, and parallel transfer of up to 36 independent film units in a single shot,is demonstrated. Thus, the solid-state kinetic bonding principle as a viableand potentially versatile route for micro-scale AM of metals is established.