Physicochemical Surface Interactions of Nanoimprint Lithography Resists and Imprinted Pore Membranes.

Nanoimprint Lithography;Pore Membrane;Hydrophobicity;Imprint Resist;Breakthrough Pressure;Interfacial Free Energy;Electrical Engineering;Engineering;Electrical Engineering

Choi, Philip Y.Yoon, Euisik ;

University of Michigan

关键词: Nanoimprint Lithography;    Pore Membrane;    Hydrophobicity;    Imprint Resist;    Breakthrough Pressure;    Interfacial Free Energy;    Electrical Engineering;    Engineering;    Electrical Engineering;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/75862/choip_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

This dissertation begins by presenting the use of inorganic copolymer imprint resists, namely siloxane graft and block copolymers.These new materials are shown to have lower resist to mold adhesion such that mold-release is more reliable without delamination from the substrate.Due to the high fraction of silicon atoms, these resists have a high degree of plasma etch resistance compared to organic polymers, so they serve as excellent high-contrast masks to facilitate pattern transfer into underlaying layers.Feature sizes of 60 nm, and possibly below, can be imprinted.Copolymerized resists presented here are single-chain component systems, offering convenience over multicomponent miscible mixtures.The graft copolymers PDMS−g−PMIA and PDMS−g−PMMA demonstrated the best performance due to their higher degree of homogeneity.To achieve a greater understanding of the wetting behavior of liquid imprint resists on mold surfaces, the phenomenon has been modeled by analysis of liquid-solid interfacial energies.The calculation methods presented here are unique in that the microscopic profile of the solid surfaces were parameterized for accurate modeling of carefully measured sample sidewalls.Equilibrium free energy minimization as well as non-zero liquid pressures were used to predict the dynamic behavior of the interacting systems.Meniscus pressure calculations in particular are a new contribution.To test the wetting models and verify the predictions of wetting behavior, freestanding, porous polymer membranes were fabricated using a modified imprinting process.These durable SU-8 polymer membranes were insoluble against a variety of test fluids.Pore morphologies were controlled to the same level of nanometer-scale accuracy due to the fidelity of the NIL process used.The modified process demonstrates the possibility of applying imprint processing to micrometer-scale size regimes and three-dimensional processing.Liquid breakthrough pressures were measured on the two types of membranes.Cross-sectional profiles of the pores, accurately scanned and digitized by electron microscopy, were used to predict wetting behaviors, and the results were compared.The small pressures were measured using a sensitive manometer, and measured wetting behavior was found to be in good agreement with the model.