High molecular weight block copolymer lithography for nanofabrication of hard mask and photonic nanostructures

Sozaraj Rasappa, Hanna Hulkkonen, Lars Schulte, Sokol Ndoni, Jarno Reuna, Turkka Salminen, Tapio Niemi

    Research output: Contribution to journalArticleScientificpeer-review

    10 Citations (Scopus)

    Abstract

    An unusual dot pattern was realized via self-assembly of high molecular weight polystyrene-block-polydimethylsiloxane (PS-b-PDMS) copolymer by a simple one-step solvent annealing process, optimized based on Hansen solubility parameters. Annealing PS-b-PDMS under neutral solvent vapors at room temperature produces an ordered arrangement of dots with ∼112 nm spacing and ∼54 nm diameter. The template is highly resistant to dry etching with chlorine-based plasma, enabling its utilization on a variety of hard masks and substrates. The self-assembled PDMS dots were further exploited as a template for direct patterning of silicon, metal, and dielectric materials. This nanopatterning methodology circumvents expensive and time-consuming atomic layer deposition, wet processes, and sequential infiltration techniques. Application-wise, we show a process to fabricate nanostructured antireflection surfaces (nanocones) on a 2 in. silicon wafer, reducing the reflectance of planar silicon from 35% to below 0.5% over a broad wavelength range. Alternatively, nanocones made of TiO2 on silicon exhibit low reflectance (<3%) and improved transmittance into the substrate at the visible wavelength range. The measured optical properties concur with the simulation results. The versatility of the PS-b-PDMS templates was further utilized for nanopatterning materials such as silicon-on-insulator substrates, gallium arsenide, aluminum indium phosphide, and gallium nitride, which are important in electronics and photonics.
    Original languageEnglish
    Pages (from-to)420-429
    Number of pages10
    JournalJournal of Colloid and Interface Science
    Volume534
    Issue number15
    DOIs
    Publication statusPublished - 2018
    Publication typeA1 Journal article-refereed

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    • Publication forum level 1

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