Electron-Induced Modification of Triptycene Self-Assembled Monolayers in Context of Lithography and Nanofabrication

• Published in: Journal of physical chemistry. C Vol. 127; no. 31; pp. 15582 - 15590
• Main Authors: Zhao, Zhiyong, Fukushima, Takanori, Zharnikov, Michael
• Format: Journal Article
• Language: English
• Published: American Chemical Society 10.08.2023
• Subjects: C: Physical Properties of Materials and Interfaces
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.3c03083

Whereas monopodal aromatic self-assembled monolayers (SAMs) are broadly used as negative resists for electron beam lithography (EBL) and carbon nanomembrane (CNM) fabrication, multipodal SAMs have been hardly utilized for these purposes. To resolve this drawback, we tested the respective performance of a model aromatic–aliphatic tripodal system, a SAM of 1,8,13-trimercaptomethyl-triptycene (Trip-T1) on Au(111). Upon electron irradiation, this SAM exhibits a behavior similar to that of traditional aromatic monolayers, featuring an extensive chemical modification but a clear dominance of intermolecular cross-linking. Lithographic experiments show that the cross-linking of Trip-T1, induced by electron-beam treatment, could protect the underlying substrate from etching, proving its suitability as a negative resist in EBL, similar to the benzylthiol (PT1) monolayer tested as a direct reference to Trip-T1. Finally, robust and defect-free CNMs could be successfully fabricated from the Trip-T1 SAM, which, however, required a somewhat higher dose (80 mC/cm2) than for the reference PT1 monolayer. Both the latter film and Trip-T1 SAM feature the lowest lateral material densities used to date for the CNM fabrication, which makes them unique in this regard.