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

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review


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 (
Original languageEnglish
JournalJournal of Colloid and Interface Science
Pages (from-to)420-429
Publication statusPublished - 2019


  • Antireflection coating
  • Gallium nitride
  • Hard mask
  • High molecular weight
  • PDMS-rich PS-b-PDMS
  • Solar cells
  • TiO2


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