Physico-chemical elucidation of the mechanism involved in optical lithography: Micro-fabrication of 2D and 3D platforms

NATALIA PHILIPP; ANGRIMAN SOFIA; BURNE SOFIA; CARAL PAULA; GOMEZ FLORENCIANO IGNACIO; RAPAGNANI NICOLAS; GABRIEL MANUELA; ESTRADA LAURA

JOURNAL OF APPLIED PHYSICS

AMER INST PHYSICS

Lugar: New York; Año: 2022

0021-8979

Direct laser lithography has attracted much attention as a convenient micro-fabrication method to develop rapid, free-form, and low-cost19 microstructures. In this work, different microdevices were fabricated using a home-made two-photon excitation microscope and a commercial20 negative UV photoresin. The mechanism involved during the fabrication of the devices as well as the effects of the irradiation intensity and21 removal time on micro-patterns was investigated by optical microscopy. For the characterization of the microstructures, scanning electron22 microscopy, atomic force microscopy, Nuclear Magnetic Resonance (1H-NMR), and Fourier transform infrared spectroscopy were used. High23 resolution optical characterization shows an enormous uniformity and high reproducibility of fabricated platforms in two and three dimensions.24 These results prompted us to propose a different mechanism not compatible with a polymerization reaction as the triggering mechanism for25 the interaction between light and the photoresin. We demonstrate the coexistence of an allylic photo-induced reaction with a photo-induced26 polymerization effect during the fabrication process. We studied the influence of these mechanisms by fabricating micro-patterns in two condi27 tions, with and without the presence of a polymerization initiator [azobisisobutyronitrile (AIBN)], which boots the polymerization reaction.28 Even though the two mechanisms are present during the fabrication process, the polymerization is dominant in the presence of a photo-initia29 tor as AIBN. Finally, we discuss the applications of our microdevices as suitable platforms for industry and biomedical applications.