Highly-efficient growth of cobalt nanostructures using focused ion beam induced deposition under cryogenic conditions: application to electrical contacts on graphene, magnetism and hard masking

Alba Salvador-Porroche; Soraya Sangiao; César Magén; Mariano Barrado; Patrick Philipp; Daria Belotcerkovtceva; M Venkata Kamalakar; Pilar Cea; José María De Teresa

doi:10.1039/d1na00580d

Highly-efficient growth of cobalt nanostructures using focused ion beam induced deposition under cryogenic conditions: application to electrical contacts on graphene, magnetism and hard masking

Nanoscale Adv. 2021 Aug 25;3(19):5656-5662. doi: 10.1039/d1na00580d. eCollection 2021 Sep 28.

Authors

Alba Salvador-Porroche¹, Soraya Sangiao^{1

2}, César Magén^{1

2}, Mariano Barrado², Patrick Philipp³, Daria Belotcerkovtceva⁴, M Venkata Kamalakar⁴, Pilar Cea^{1

2}, José María De Teresa^{1

2}

Affiliations

¹ Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza 50009 Zaragoza Spain deteresa@unizar.es j.deteresa@csic.es.
² Laboratorio de Microscopías Avanzadas (LMA), Universidad de Zaragoza 50018 Zaragoza Spain.
³ Advanced Instrumentation for Nano-Analytics (AINA), MRT Department, Luxembourg Institute of Science and Technology (LIST) 41 rue du Brill 4422 Belvaux Luxembourg.
⁴ Department of Physics and Astronomy, Uppsala University Box 516 SE-751 20 Uppsala Sweden.

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.