As easy as “shake and bake”, the mixing and photocuring of poly‐functional thiols with alkene‐functional cross‐linkers, via thiol‐ene click chemistry, leads to materials with outstanding and tunable characteristics for soft imprint lithography. The materials are cured within 2 minutes at ambient conditions allowing stamps with high aspect ratio and sub‐100 nm features to be fabricated.
This paper describes composite patterning elements that use a commercially available acryloxy perfluoropolyether (a-PFPE) in various soft lithographic techniques, including microcontact printing, nanotransfer printing, phase-shift optical lithography, proximity field nanopatterning, molecular scale soft nanoimprinting, and solvent assisted micromolding. The a-PFPE material, which is similar to a methacryloxy PFPE (PFPE-DMA) reported recently, offers a combination of high modulus (10.5 MPa), low surface energy (18.5 mNm(-1)), chemical inertness, and resistance to solvent induced swelling that make it useful for producing high fidelity patterns with these soft lithographic methods. The results are comparable to, and in some cases even better than, those obtained with the more widely explored material, high modulus poly(dimethylsiloxane) (h-PDMS).
A noninvasive fabrication process involving soft nanoimprint lithography is used to pattern a photonic crystal (PhC) in titania film for enhanced light extraction from a GaN light emitting diode (LED). This technique avoids damaging the LED structure by the etching process, while photoluminescence measurements show extracted modes emitted from the quantum wells which agree well with modeling. A light extraction improvement of 1.8 times is measured using this noninvasive PhC.
We report the performance and characterization of a material based on poly[(3-mercaptopropyl)methylsiloxane] (PMMS) in various soft lithography applications. PMMS stamps were made by cross-linking with triallyl cyanurate and ethoxylated (4) bisphenol A dimethacrylate via thiol−ene mixed-mode chemistry. The surface chemistry of the materials was characterized by XPS when varied from hydrophilic through oxygen plasma treatment, to hydrophobic by exposure to a fluorinated trichlorosilane agent. The materials are transparent above 300 nm and thermally stable up to 225 °C, thus rendering them capable to be employed in step-and-flash imprint lithography, nanoimprint lithography, nanotransfer printing, and proximity-field nanopatterning. The successful pattern replication from the micrometer to sub-100 nm scale was demonstrated.
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