Polymer Masks Fabrication by Micropatterning Surfaces of Composite Polymer Coatings

Abstract

Micropatterning of surfaces has been demonstrated using composite polymer coatings of PS and PMMA of equal molecular weights in different volume proportions with varying surface topographies on silicon surfaces. The creation of PMMA masks with various surface morphological features has also been demonstrated by removal of PS from the composite coatings using cyclohexane. Atomic force microscopy (AFM) investigations revealed that the surface pattern and the dimensions of these masks significantly changed with the change in the volume proportions of each homopolymer. The composite coatings of 20/80 vol% PS/PMMA, 50/50 vol% PS/PMMA, and 80/20 vol% PS/PMMA resulted in PMMA masks with holes (depth ∼300 nm), wrinkles (height ∼350 nm) and pillars (height ∼600 nm), respectively. Surface compositional analysis carried out using FTIR and XPS investigations confirmed the presence of polymer coatings of PS, PMMA and PS/PMMA. XPS investigations also confirmed the successful removal of PS from the PMMA mask by showing the presence of the silicon substrate on those masks where PS was previously present. The water contact angle of the composite polymer masks ranged from 70 to 90° which increased with the increase of PS vol% in the composite. The wetting behavior of certain PMMA masks showed hydrophobicity with water contact angle values above 90°.