E-beam lithography and cryo-etching for the definition of sharp edges in 2D-materials

Vito Clericò
Group of Nanotechnology, USAL-NANOLAB,  
Universidad de Salamanca, E-37008 Salamanca, Spain

A detailed introduction of SEM (scanning electron microscope) and EBL (electron beam lithography) will be shown in the first part of the talk. Correction of SEM parameters, EBL alignment and main limitation of EBL technique will be described thought the use of common examples [1].

Some application of EBL technique on 2D materials are presented in the second part of the talk. Also in this case a detailed description of the whole process (including main problems) to obtain a final device is shown [2][3].

In the last part of the talk the role of the temperature in an ICP-RIE process is described. A very controllable etching process is fundamental for the realization of ‘side’ or ‘edge’ contacts in encapsulated 2D materials. Besides, through the use of cryogenic temperature in the etching process, we were able to obtain nanostructures with very small roughness in comparison with higher etching temperatures. A clear conductance quantization was so observed in encapsulated graphene constriction [4].

[1] V. Clericò, M. Amado, E. Diez Electron beam lithography and its use on 2D materials (Chapter 3), Book Nanofabrication: nanolithography techniques and their applications Institute of Physics, UK, 2020.

[2] D. Vaquero, V. Clericò, J. Salvador-Sánchez, A. Martín-Ramos, E. Díaz, F. Domínguez-Adame, Y. M. Meziani, E. Diez y J. Quereda  Excitons, trions and Rydberg states in monolayer MoS2 revealed by low-temperature photocurrent spectroscopy, Comm. Phys. volume 3, 194 (2020)

[3] J. A. Delgado-Notario, V. Clericò, E. Diez, J. E. Velázquez-Pérez, T. Taniguchi, K. Watanabe, T. Otsuji, and Y. M. Meziani Asymmetric dual-grating gates graphene FET for detection of terahertz radiations, APL Photonics 5, 066102 (2020)

[4] V. Clericò, J.A. Delgado-Notario, M. Saiz-Bretín, A.V. Malyshev, Y. M. Meziani, P. Hidalgo, B. Méndez, M.Amado, F. Domínguez-Adame and E. Diez Quantum nanoconstrictions fabricated by cryo-etching in encapsulated graphene Scientific Reports 9, 13572 (2019)

Vito Clericò is clean room technical manager at the University of Salamanca since November 2013. After his master degree in Matter Physics in 2010, he worked for two years (2011-2013) as research assistant at NEST (National Enterprise for Nanoscience and nanoTechnology) in Pisa (Italy).  He received his PhD degree in February 2020 in Salamanca. The topic of the PhD thesis was “Fabrication and characterization of Quantum Materials: Graphene heterostructures and Topological Insulators”. In Salamanca he has significantly contributed to realize the first nanotechnology clean room of Castilla y León, where he nanofabricated the first devices. His field of competence includes nanofabrication techniques (e-beam lithography, SEM imaging,Uv-vis lithography, e-beam evaporation, thermal evaporation, dry etching with ICP-RIE and RIE, wet etching, ALD and sputter deposition, rapid thermal annealing, etc…).