Islam Sourav, Sangermano Marco, Klar Thomas A
Institute of Applied Physics, Johannes Kepler University Linz, 4040 Linz, Austria.
Department of Applied Science and Technology, Politecnico Di Torino, 10124 Torino, Italy.
J Phys Chem C Nanomater Interfaces. 2023 Sep 7;127(37):18736-18744. doi: 10.1021/acs.jpcc.3c04394. eCollection 2023 Sep 21.
Direct laser writing by two-photon lithography has been enhanced substantially during the past two decades by techniques borrowed from stimulated emission depletion (STED) microscopy. However, STED-inspired lithography was so far limited to radical polymerizations, mostly to acrylates and methacrylates. Cationic polymers did not derive benefits from this technique. Specifically, epoxide polymerization, which plays a paramount role in semiconductor clean-room technology, has not yet been reported with a second, depleting laser focus in the outer rim of the point spread function. We now found that using a thioxanthone as a sensitizer and sulfonium or iodonium salts as photoinitiators enables at least partial optical on/off switching of two-photon polymerization and, in the case of the sulfonium salt, allows for writing epoxy lines with widths shrunk by approx. two-thirds compared to lines written with two-photon polymerization alone.
在过去二十年中，通过借鉴受激发射损耗（STED）显微镜技术，双光子光刻的直接激光写入技术有了显著提升。然而，受STED启发的光刻技术迄今为止仅限于自由基聚合反应，主要是丙烯酸酯和甲基丙烯酸酯的聚合。阳离子聚合物尚未从该技术中受益。具体而言，在半导体洁净室技术中起着至关重要作用的环氧化合物聚合反应，尚未有关于在点扩散函数的外边缘使用第二个耗尽激光焦点的报道。我们现在发现，使用噻吨酮作为敏化剂，锍盐或碘鎓盐作为光引发剂，能够实现双光子聚合至少部分的光学开/关切换，并且在使用锍盐的情况下，可以写出宽度比仅使用双光子聚合写出的线条缩小约三分之二的环氧线条。
