SU-8 for real three-dimensional subdiffraction-limit two-photon microfabrication

The utility of two-photon-absorption (TPA) for the fabrication real three-dimensional photoplastic structures with subdiffraction limit (SDL) resolution, based on SU-8 as the polymer matrix was discussed. The TPA photopolymerization process was used as a shutter mechanism for disruptive three-dimensional lithography. The SU-8 lines fabrication was studied by scanning the laser focal spot in regularly spaced straight lines above the 975 nm SU-8/Si interface. Analysis shows that a rapid drop in linewidth as a function of scanning speed was observed which was caused by the incomplete protolysis of the cationic photoinitiator in SU-8.