Fabrication of high aspect ratio nanostructures using capillary force lithography
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A new ultraviolet (UV) curable mold consisting of functionalized polyurethane with acrylate group (MINS101m, Minuta Tech.) has recently been introduced as an alternative to replace polydimethylsiloxane (PDMS) mold for sub-100-nm lithography. Here, we demonstrate that this mold allows for fabrication of various high aspect ratio nanostructures with an aspect ratio as high as 4.4 for 80 nm nanopillars. For the patterning method, we used capillary force lithography (CFL) involving direct placement of a polyurethane acrylate mold onto a spin-coated polymer film followed by raising the temperature above the glass transition temperature of the polymer (Tg). For the patterning materials, thermoplastic resins such as polystyrene (PS) and poly(methyl methacrylate) (PMMA) and a zinc oxide (ZnO) precursor were used. For the polymer, micro/nanoscale hierarchical structures were fabricated by using sequential application of the same method, which is potentially useful for mimicking functional surfaces such as lotus leaf.
Key wordsCapillary Force Lithography Nanostructures Aspect Ratio Laplace Pressure
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- Brandup, J. and Immergut, E. H.,Polymer Handbook, Wiley, New York (1989).Google Scholar
- Seo, S. M., Park, J.Y. and Lee, H. H., “Micropatterning of metal substrate by adhesive force lithography,”Appl. Phys. Lett.,86, (2005). As described in this paper, we used the relation γ1(1+cosθ)= 2(γ sdγ1d)1/2+2(γ spγ1p)1/2 to estimate the contact angle of PMMA on PUA mold (θ), where the superscripts d and p are for the dispersion and polar components of the surface tensionγ. Calculated dispersion and polar components surface tensions of PUA mold and PMMA are as follows: γPUAd=21.6, γPUAp=33.3 (PUA=solid), γPMAd=39.89, γPMMAp= 3.17mJ/m2 (PMMA=liquid). From these values,θ =33.3o was obtained.Google Scholar
- Wu, S., Polymer Interface and Adhesion, Dekker, New York (1982).Google Scholar