Effect of angstrom-scale surface roughness on the self-assembly of polystyrene-polydimethylsiloxane block copolymer

Abstract

Self-assembly of block copolymers has been identified as a potential candidate for high density fabrication of nanostructures. However, the factors affecting its reliability and reproducibility as a patterning technique on various kinds of surfaces are not well-established. Studies pertaining to block copolymer self-assembly have been confined to ultra-flat substrates without taking into consideration the effect of surface roughness. Here, we show that a slight change in the angstrom-scale roughness arising from the surface of a material creates a profound effect on the self-assembly of polystyrene-polydimethylsiloxane block copolymer. Its self-assembly was found to be dependent on both the root mean square roughness (Rrms) of the surface and the type of solvent annealing system used. It was observed that surface with Rrms< 5.0 Å showed self-assembly. Above this value, the kinetic hindrance posed by the surface roughness on the block copolymer leads to its conforming to the surface without observable phase separation.

Manufacturing Over Many Scales: High Fidelity Macroscale Coverage of Nanoporous Metal Arrays via Lift‐Off‐Free Nanofabrication

“…The authors claimed that a substrate with a root mean square roughness (R rms ) larger than 5 Å does not allow the self assembly of their PS-PDMS spherical BCPs whose PDMS centers are 40 nm apart. In our study, unlike Kundu et al's claim, [ 26 ] large roughness did not prevent self assembly completely. We deposited Au on bare Si wafers with various thicknesses from 30 nm to 200 nm in order to obtain various surface roughness values ( Figure 2 ).…”

“…[ 33,34 ] Another recent study by Kundu et al [ 26 ] on the effect of surface roughness on the self assembly of polystyrene-polydimethylsiloxane (PS-PDMS) BCPs hints that the roughness of the metal substrate could impede the mobility of the polymer blocks under constraint, thus disrupting the self assembly. The authors claimed that a substrate with a root mean square roughness (R rms ) larger than 5 Å does not allow the self assembly of their PS-PDMS spherical BCPs whose PDMS centers are 40 nm apart.…”

“…[ 20 ] Recently, BCP lithography has been nearly perfected with achieving a periodicity over a wafer scale, yet enabled by additional sparse patterning of lithographically-defi ned chemical [ 21,22 ] or physical templates. [23][24][25] BCPs can take different nanostructured morphologies of spherical, [ 20,26 ] cylindrical (columnar hexagonal) [ 20,22 ] or lamellar [ 25,27 ] blocks via microphase segregation. Compared with spherical ones, cylindrical BCPs have been more popular among researchers due to their high aspect ratio and negligible residual layers.…”

Uniformity analysis in nanocrystalline silver thin films using fuzzy inference system

“…It is observed that when the FSM values are high, the UM will be depending more on the NR values, and hence, w 3 and w 4 are computed with a weight 3 given to the NR membership value as shown in Eqns (11) and (12). The outputs z 1 , z 2 , z 3 , and z 4 of each fuzzy rule are defined as…”

“…[11] AFM images are used to measure root mean square roughness, which helps in analyzing the surface characteristics of nanostructures. [12] Scattering techniques have also been used for analyzing the surface roughness. [13] Eraldo Riberiro and Mubarak Shah [14] has mentioned the use of texture analysis to characterize nanoscale materials as one of the possible avenues for future research in nanoscale imaging.…”