Enhancement the space between structureson PS-b-PMMA BCPs self-assembly processing

we discuss in this work a practical approach to control the distance between the nanostructures in the self-assembly process in block copolymers (BCP) thin films (PS-b-PMMA). The thermodynamics governs this self-assembly process by forcing the space between the structures and the feature size to be the same, 1: 1 pattern. However, some applications of the BCPs produced template require un-equal space-feature pattern for a given pitch, which cannot be readily generated by a standard BCPs self-assembly process. The aim of this work is to investigate to overcome this limitation. The first approach used is testing the effect of thermal annealing on periodicity. The result was not relevant. Blending with homopolymer was another option to enhance the space between structures. The last approach was the "hole in hole" method, which gives a promising result for the target behind this work.