In this work, we report a simple and inexpensive UV-LEDs based photomicroreactor assembly constructed by commercially available components. The photoisomerization of norbornadiene to quadricyclane was selected to validate this novel photomicroreactor design. Mass transport limitation was eliminated and indicated by dimensionless numbers Fo and Da II , and photons loss was evaluated considering the absorption and reflection of the microreactor walls. The solvents, photosensitizers, and light sources selections were optimized for achieving better photochemical performance and mechanistic insights. The detailed comparison between the high-pressure mercury arc lamp and the UV-LEDs strip revealed great potential of UV-LEDs as appealing light source for photochemical transformations. Moreover, the reaction mechanism was thoroughly discussed and illustrated by the Jablonski diagram indicating electronic states transitions. According to possible intermediate steps, a kinetic model was proposed with the reaction rate constant being correlated with the photon flux, which is valuable for process optimization and further understanding reaction mechanisms.
Xiaofei Liu,Tianren Liu,Kaixin Su,Jingxin Lei,Yuanfu Chen,Yuan Chen,Dongxu Yang
As metal-containing resists attract increasing research interest in high-resolution lithography, gaining insights into the photochemical mechanisms, particularly in relation to the ligand functionality, is actively demanded. In this work, a controlled pair of organotin carboxylates with analogous structures but different functional groups has been designed and synthesized as deep-ultraviolet (DUV) resists. Both resists demonstrate 90 nm half-pitch resolution and the capability of pattern transfer on carbon-based hard-mask layers. Through various characterizations and comparison of the controlled pair, we propose two competitive reaction paths for the organotin system with olefin groups, which regulate the lithographic sensitivity and dissolution contrast. Our findings highlight the structural adjustability of organotin carboxylates and their potential application as high-resolution and etch-durable DUV resists.
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