Spirothiopyran based super-resolution interference lithography

Vijayamohanan, Harikrishnan
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Ullal, Chaitanya
Palermo, Edmund
Hull, Robert, 1959-
Ryu, Chang Yeol
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Materials engineering
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In this thesis, we develop a new super-resolution writing system with the desired low light thresholds for parallel nanopatterning by combining the reversibly saturable isomerization of photochromic spirothiopyran with the thiol-Michael addition reaction. To study the kinetics and optimize the minimum feature sizes realizable with the spirothiopyran writing chemistry, a 1D super-resolution patterning prototype system was designed for self-assembled monolayers on glass substrates. The switchable photoresponsive surfaces fabricated are capable of direct writing various maleimide functionalized molecules in solution. The kinetics of spirothiopyran photoswitching in the monolayer is found to be highly sensitive to the chemical microenvironment. After optimizing the monolayer composition, we experimentally demonstrate large area 1D nanopatterning with 90 nm feature size and using a 2-color interference lithography setup. The lateral feature size of the written patterns is shown to be tunable by controlling the relative intensity of the initiation and inhibition wavelengths. The resultant nanopatterns formed are characterized using super-resolution microscopy. The kinetics of the writing system were examined in detail with the aid of a numerical model, and the factors affecting the overall resolution and contrast were identified. We further adapt this material system to pattern photoresponsive polymers for bulk volume nanopatterning. These results mark important steps toward realizing a highly parallelized fabrication technique with nanoscale resolution, over large volumes in three dimensions.
August 2019
School of Engineering
Dept. of Materials Science and Engineering
Rensselaer Polytechnic Institute, Troy, NY
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