Microdomain orientation dependence on thickness in thin films of cylinder-forming PS-b-PMMA

Abstract

The self-assembly of block-copolymer thin films in periodic nanostructures has received considerable attention during the last decade due to their potential applications in nanofabrication and nanolithography. We followed the morphologies developed in thin films of a cylinder-forming diblock copolymer polystyrene-b-poly(methylmethacrylate) ((PS-b-PMMA), PS 46.1 kg mol( - 1), PMMA 21.0 kg mol( - 1), lattice spacing L(0) = 36 nm), as a function of the film thickness (t), analyzing the effect of thickness commensurability on domain orientation in respect to the substrate. The study was circumscribed to the unexplored range of thickness below L(0). Two thickness windows with perpendicular orientation of the PMMA domains were identified: a well-known window at t approximately L(0) and a new window at t approximately L(0)/2. A half-parallel cylinder morphology was observed for [Formula: see text] with a progressive change in morphology [Formula: see text] when thickness increases from L(0)/2 to L(0). This experimental evidence provides new insights on the mechanism of block copolymers self-organization and indicates the possibility to tune the thickness of the nanostructured polymeric film below L(0), allowing the fabrication of ultrathin soft masks for advanced lithographic processes.

Directed Self-Assembly on Photo-Crosslinked Polystyrene Sub-Layers: Nanopattern Uniformity and Orientation

“…These BCP films were thermally annealed at 280 °C for 60 min in a nitrogen atmosphere, giving a final thickness of 30 nm that is ideal for the formation of half-cylinder structures [28]. The equilibrium period (L 0 ) and correlation length were determined for each type of sub-layer using fast Fourier transform (FFT) analysis of a low-magnification atomic force microscopy (AFM) image.…”

Strategies for Inorganic Incorporation using Neat Block Copolymer Thin Films for Etch Mask Function and Nanotechnological Application

“…This report also commented on highly ordered pattern formation irrespective of substrate as confi rmed by simulation data. This is an important point as this particular PS-b -P2VP-b -PtBMA tri-BCP avoided complex brush modifi cations unlike those required for di-BCP counterparts, e.g., PS-b -PMMA [ 191 ] or PS-b -PDMS. [ 192 ] A work by Aizawa et al [ 193 ] in 2006 demonstrated the patterning of two metals at substrate surfaces using aqueous metal reduction and a PS-b -P2VP-b -PEO system, however, ordered uniform patterns were not formed.…”

Silicon crystallization in nanodot arrays organized by block copolymer lithography

“…The annealing was performed under vacuum (p = 3 9 10 -2 mbar) at 190°C for 2 h to promote self-organization into hexagonal arrangements of PMMA cylinders in a PS matrix with diameter (d) and lattice spacing (L 0 ) ( Fig. 1b) dictated by the molecular weight of the specific macromolecule (Zucchi et al 2010). Exposure under an ultraviolet lamp (5 mW/cm 2 , k = 253.7 nm, 90 min) degraded the PMMA and cross-linked the PS matrix.…”