Mechanism and dynamics of block copolymer directed assembly with density multiplication on chemically patterned surfaces
(Color online) Schematic of the block copolymer directed assembly with 2× density multiplication on a chemical pattern.
Top-down SEM images of thin films of annealed at for various times [(a)–(g) show images of block copolymer annealed for 10 min, 30 min, 1 h, 2 h, 4 h, 16 h, and 64 h, respectively] on chemical patterns designed for density multiplication and (h) for 10 min on chemical patterns without density multiplication. The chemically patterned lines on the PS brush run from top to bottom in the images. The natural period of block copolymer, , was 47.7 nm, and the pattern period, , was 100 nm . PS appears light and PMMA appears dark. Each image represents an area of .
(Color online) SAXS patterns of the in situ annealing of on chemically patterned surfaces designed for density multiplication. The temperature was ramped from 40 to for 6 min and held at afterward. The scattering peak characteristic of 100 nm spacing appeared in the pattern of and was about to disappear in the pattern of . The dark rectangle in the pattern is an empty area between two adjacent detector modules. The bright lines across the patterns are scattering noise from the scratches on the sample that were used to locate the pattern areas.
SAXS spectra of directed assembly with density multiplication on chemically patterned surfaces for various annealing times, as shown in the graph. The temperature was ramped from 40 to for 6 min and held at for . The first-order scattering peak of 100 nm spacing appeared at and disappeared at . The spectra are offset, and only the first characteristic peaks are plotted for clarity. The spectra for times less than 1 h were acquired in situ, and those for 1 and 24 h spectra are ex situ. The first-order characteristic scattering peak at 100 nm appeared at and disappeared at . The unit of the intensity is arbitrary.
(Color online) Cross-sectional average compositions obtained from steps of a Monte Carlo simulation of directed assembly of with density multiplication. The chemical pattern and the scale bar are illustrated at the bottom. The period of the chemical pattern is 100 nm, and the width of PMMA wetting stripe is 25 nm.
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