Arrays of Densely Packed Isolated Nanowires by Focused Beam Induced Deposition Plus Ar⁺ Milling

Abstract

One of the main features of any lithography technique is its resolution, generally maximized for a single isolated object. However, in most cases, functional devices call for highly dense arrays of nanostructures, the fabrication of which is generally challenging. Here, we show the growth of arrays of densely packed isolated nanowires based on the use of focused beam induced deposition plus Ar(+) milling. The growth strategy presented herein allows the creation of films showing thickness modulation with periodicity determined by the beam scan pitch. The subsequent Ar(+) milling translates such modulation into an array of isolated nanowires. This approach has been applied to grow arrays of W-based nanowires by focused ion beam induced deposition and Co nanowires by focused electron beam induced deposition, achieving linear densities up to 2.5 × 10(7) nanowires/cm (one nanowire every 40 nm). These results open the route for specific applications in nanomagnetism, nanosuperconductivity, and nanophotonics, where arrays of densely packed isolated nanowires grown by focused beam deposition are required.

Thickness-modulated tungsten–carbon superconducting nanostructures grown by focused ion beam induced deposition for vortex pinning up to high magnetic fields

“…2, FIBID allows the growth of W–C films that are either flat or display engineered thickness modulation (corrugation). In the present work, the thickness corrugation arises mainly at the interface between the film and the substrate because during growth, the ion beam removes substrate material from the scanned areas [22]. During growth, the ion beam is scanned following linear paths, which produces characteristic grooves and crest–valley-structured films.…”

“…Even small surface corrugations of just a few percent of the total thickness allow the observation of vortex-lattice matching effects by means of scanning tunneling microscopy (STM) [20–21]. Recently, De Teresa and Córdoba proposed a strategy to grow W–C films by FIBID with controlled thickness modulation [22], which opens the route for the design of specific experiments probing the behavior of the vortex lattice as a function of magnetic field, temperature and electrical current. In the present work, we exploit such a strategy to create linear-shape vortex-pinning landscapes in W–C films grown by FIBID.…”

Mechanical magnetometry of Cobalt nanospheres deposited by focused electron beam at the tip of ultra-soft cantilevers

“…We were then able to grow by FEBID roughly spherical Co nanoparticles having the requested lateral dimensions at the very end of the special V-shape tip of the cantilever. The precursor used for growing these Cobalt nanospheres was Co 2 (CO) 8 as previous work has demonstrated the growth of ultra-small magnetic structures (< 30 nm) using this approach [27,28]. When the precursor was introduced close to the cantilever tip, the chamber vacuum pressure changed from 1 · 10 -6 mbar (base pressure) to 8.5 · 10 -6 mbar (process pressure).…”

Present and future applications of magnetic nanostructures grown by FEBID

“…Therefore, beneficial effects that could result from unique features of FEBID, such as the Gaussian profile of the deposits [12], its ultrahigh resolution [4,54] or the possibility to tune different thicknesses at different parts of a magnetic circuit in a single lithography step [22], should be exploited so that patterning these devices by FEBID became advantageous. In this direction, De Teresa and Córdoba [55] have recently grown Co deposits where the thickness is strongly modulated with short periodicity of 40 nm, as shown in Fig. 8.…”

“…From such deposits, arrays of highly dense isolated nanowires have been obtained after a gentle Ar ? milling, circumventing one of the problems of dense patterns in FEBID: the connecting base layer caused by precursor dissociation beyond the incidence point of the electron beam [55]. This strategy could be further exploited towards generation of highly dense isolated structures with arbitrary form.…”