Abstract
Emergent technologies are required in the field of nanoelectronics for improved contacts and interconnects at nano and micro-scale. In this work, we report a highly-efficient nanolithography process for the growth of cobalt nanostructures requiring an ultra-low charge dose (15 μC cm−2, unprecedented in single-step charge-based nanopatterning). This resist-free process consists in the condensation of a ∼28 nm-thick Co2(CO)8 layer on a substrate held at −100 °C, its irradiation with a Ga+ focused ion beam, and substrate heating up to room temperature. The resulting cobalt-based deposits exhibit sub-100 nm lateral resolution, display metallic behaviour (room-temperature resistivity of 200 μΩ cm), present ferromagnetic properties (magnetization at room temperature of 400 emu cm−3) and can be grown in large areas. To put these results in perspective, similar properties can be achieved by room-temperature focused ion beam induced deposition and the same precursor only if a 2 × 103 times higher charge dose is used. We demonstrate the application of such an ultra-fast growth process to directly create electrical contacts onto graphene ribbons, opening the route for a broad application of this technology to any 2D material. In addition, the application of these cryo-deposits for hard masking is demonstrated, confirming its structural functionality.
Highlights
The fabrication of functional nanostructures by the top-down approach generally involves the use of thin- lm deposition and nanolithography techniques.[1]
This resist-free process consists in the condensation of a $28 nm-thick Co2(CO)[8] layer on a substrate held at À100 C, its irradiation with a Ga+ focused ion beam, and substrate heating up to room temperature
We focus our attention on the resist-free growth of functional nanostructures by means of focused ion beam induced deposition (FIBID).[17]
Summary
We focus our attention on the resist-free growth of functional nanostructures by means of focused ion beam induced deposition (FIBID).[17] FIBID consists in the adsorption of precursor molecules provided by a gas injection system (GIS) on the substrate surface, which are dissociated by a focused ion beam (typically based on Ga+), producing the growth of a deposit In this technique, generally performed at room temperature, a single monolayer of precursor molecules is 5656 | Nanoscale Adv., 2021, 3, 5656–5662. The growth rate in FIBID can be increased several orders of magnitude if the precursor molecules form a thick layer where most of the beam energy is absorbed and efficiently used for molecule dissociation This can be achieved through cooling the substrate below the precursor condensation temperature.[19,20,21,22,23,24] This Cryo-FIBID approach holds an enormous potential for rapid patterning of metallic micro/nano-deposits.
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