Microsputterer with integrated ion-drag focusing for additive manufacturing of thin, narrow conductive lines

Abstract

We report the design, modelling, and proof-of-concept demonstration of a continuously fed, atmospheric-pressure microplasma metal sputterer that is capable of printing conductive lines narrower than the width of the target without the need for post-processing or lithographic patterning. Ion drag-induced focusing is harnessed to print narrow lines; the focusing mechanism is modelled via COMSOL Multiphysics simulations and validated with experiments. A microplasma sputter head with gold target is constructed and used to deposit imprints with minimum feature sizes as narrow as 9 µm, roughness as small as 55 nm, and electrical resistivity as low as 1.1 µΩ · m.

Employing a MEMS plasma switch for conditioning high-voltage kinetic energy harvesters

“…Yet, such macroscopic plasma sources were inaccurate, unstable, large-size and difficult to be controlled. Fortunately, the emerging microplasma technology that miniaturized the inter-electrode separation [55][56][57] made it possible to create stable plasma sources at low-vacuum pressure or even atmospheric that are otherwise only possible to be created at extreme conditions. The microplasma technique opens the door to a wide range of new exciting applications, and here we apply microplasma as a high-voltage switch to solve the pain points in the energy harvesting conditioning circuits.…”

Fully 3D‐Printed, Ultrathin Capacitors via Multi‐Material Microsputtering

“…Therefore, a method to create dielectric films from DC sputtered aluminum shaped into a wire was developed. Previous microsputtering studies have used compressed dry air or argon as the sputtering gas; [43][44][45][46][47][48] while these are sufficient to sputter materials such as gold and copper, they cannot sputter aluminum, as aluminum needs more energetic ions to strip the aluminum atoms from the target wire. Increasing the ion energy by increasing the power fed to the plasma is not a viable solution, as the high current can melt the thin target wire.…”

Biomedical Applications of Metal 3D Printing

“…Sputtering is normally conducted in vacuum; however, plasmas can be stable at atmospheric pressure if the interelectrode distance is reduced to millimeters or less-these plasmas are called microplasmas. Microplasma sputtering (μPS) (Figure 1f ) is a relatively new technology for metal 3D printing of micro-and nanosystems that can deposit metal at room temperature on a wide range of materials, including temperature-sensitive substrates (99)(100)(101)(102)(103)(104)(105). There is an experimental DED technique that uses an arc plasma as an integrating agent, known as plasma-arc directed energy deposition (DED-PA), but it produces large structures with low precision, resolution, and surface quality (19); instead, μPS uses a low-current glow discharge for finer process control.…”

“…Because μPS does not use binder, it creates imprints with near-bulk electrical conductivity without annealing (∼85% bulk value for gold), surpassing competing technologies such as electrohydrodynamic deposition (jetting of metal micro/nanoparticle solutions using high electric fields; see 106-108), laser-assisted electrophoretic deposition (creation of deposits via electrophoresis of metal micro-and nanoparticles confined by high-intensity photons; see 109), laser-induced forward transfer (direct transfer by laser ablation of materials sourced as a thin film on a transparent substrate; see 110, 111), meniscus-confined electroplating (see 112,113), laser-induced photoreduction (photochemical reduction of metal salt solutions using a rastering laser; see [114][115][116], and focused-ion-beam-induced deposition (deposition of metallic molecules from the ion-induced dissociation of gases; see 117, 118) (Table 2). In principle, many materials can be sputtered, but the reported μPS work focuses on gold and copper (see [99][100][101][102][103][104]. Because of the slow speed of the process, μPS is primarily used for metallic coatings, rather than metal objects, which can be used to integrate metal traces to the surfaces of free-form objects, for example, to implement skin electronics.…”