Description
Two-photon lithography, enhanced by stimulated emission depletion (STED) principles, hassignificantly advanced direct laser writing, primarily benefiting radical polymerization systems [1,2].
However, its application to cationic polymerization, especially in epoxide-based systems widely used
in microfabrication, remains largely unexplored, despite the latter’s advantages, including lower
monomer toxicity, reduced shrinkage stress, improved adhesion, and resistance to oxygen inhibition.
In our recent work [3,4], we investigated a resist containing 3,4-epoxycyclohexylmethyl 3,4
epoxycyclohexanecarboxylate (EPOX) as the monomer, triarylsulfonium hexafluoroantimonate salt
as photo-initiator and 2-isopropylthioxanthone (ITX) as a photosensitizer. Using a 780 nm
femtosecond laser for two-photon excitation, we successfully produced polymer structures with a
feature size of 418 nm. Introducing an additional component to the resist system as a quenching
agent [5], Ethyl 4-(dimethylamino)benzoate (EDAB), resulted 70% polymerization quenching.
Furthermore, by employing a 450 nm multimode continuous-wave (CW) diode laser for depletion in
combination with a half-spaced phase mask, we identified an alternative depletion mechanism in this
system, enabling the fabrication of structures with a feature size of 195 nm.
| Period | Feb 2025 |
|---|---|
| Event title | 10th Conference on Applications of Femtosecond Lasers in Materials Science |
| Event type | Conference |
| Location | 5570 Mauterndorf, AustriaShow on map |
| Degree of Recognition | International |
Fields of science
- 210005 Nanophotonics
- 103016 Laser physics