Conductivity of SU-8 Thin Films through Atomic Force Microscopy Nano-Patterning

• Published in: Advanced functional materials Vol. 22; no. 7; pp. 1482 - 1488
• Main Authors: Martin-Olmos, Cristina, Villanueva, L. Guillermo, van der Wal, Peter D., Llobera, Andreu, de Rooij, Nico F., Brugger, Jürgen, Perez-Murano, Francesc
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 10-04-2012; WILEY‐VCH Verlag
• Subjects: atomic force microscope (AFM); dielectric properties; nano-electrode arrays; scanning probe lithography (SPL); SU-8
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201102789

Processing flexibility and good mechanical properties are the two major reasons for SU‐8 extensive applicability in the micro‐fabrication of devices. In order to expand its usability down to the nanoscale, conductivity of ultra‐thin SU‐8 layers as well as its patterning by AFM are explored. By performing local electrical measurements outstanding insulating properties and a dielectric strength 100 times larger than that of SiO2 are shown. It is also demonstrated that the resist can be nano‐patterned using AFM, obtaining minimum dimensions below 40nm and that it can be combined with parallel lithographic methods like UV‐lithography. The concurrence of excellent insulating properties and nanometer‐scale patternability enables a valuable new approach for the fabrication of nanodevices. As a proof of principle, nano‐electrode arrays for electrochemical measurements which show radial diffusion and no overlap between different diffusion layers are fabricated. This indicates the potential of the developed technique for the nanofabrication of devices.
Atomic force microscopy (AFM)‐based lithography of SU‐8 ultrathin films and its applicability for the fabrication of nano‐devices are investigated. It is shown that SU‐8 presents outstanding insulating properties and extremely high dielectric strength. A physical‐chemical mechanism responsible for the AFM‐based patterning is proposed and the potential of this AFM nanopatterning demonstrated by the pro‐totyping and testing of nanoelectrode arrays.