Fabrication of Block Copolymer Nanotemplates by One-Step Matrix-Assisted Photothermal Excimer Laser Ablation

Mask-image-like block copolymer nanotemplates with densely packed polystyrene (PS) nano-dots were prepared by a simple top-down/bottom-up hybrid method using one-step excimer laser irradiation on perpendicular cylinder-containing block copolymer masks. Together with preferential etching of more ultraviolet (UV)-sensitive block component, non-selective removal of all block components, which reduced the overall sample thickness and finally provided block copolymer nanotemplates with freestanding PS nanocylinders, simultaneously occurred during the excimer laser irradiation at an appropriate laser intensity. The numerical analysis on the photothermal ablation of periodically nanopatterned block copolymer masks revealed that, by using sufficiently low laser intensity, we could suppress the microscopic level surface melt flows of block components, as long as the intensity was high enough to induce a matrix- assisted photothermal ablation in the less UV-sensitive block component. Such surface melt flows would, otherwise, severely undermine the initial orders of nanopatterns in the block copolymer masks.