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

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 TiO 2 on silicon exhibit low reflectance ( 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.