# Defect removal by solvent vapor annealing in thin films of lamellar diblock copolymers

## TL;DR

Solvent vapor annealing effectively removes defects in lamellar diblock copolymer thin films by increasing spacing and controlling swelling and evaporation, crucial for nanolithography applications.

## Contribution

This study provides a systematic theoretical analysis of how solvent vapor annealing influences defect removal in lamellar BCP thin films near the order-disorder transition.

## Key findings

- Increased lamellar spacing improves defect removal efficiency.
- Defect stability depends on BCP swelling and solvent evaporation rate.
- SVA mechanism is validated for producing defect-free BCP films.

## Abstract

Solvent vapor annealing (SVA) is known to be a simple, low-cost and highly efficient technique to produce defect-free diblock copolymer (BCP) thin films. Not only can the solvent weaken the BCP segmental interactions, but it can vary the characteristic spacing of the BCP microstructures. We carry out systematic theoretical studies on the effect of adding solvent into lamellar BCP thin films on the defect removal close to the BCP order-disorder transition. We find that the increase of the lamellar spacing, as is induced by addition of solvent, facilitates more efficient removal of defects. The stability of a particular defect in a lamellar BCP thin film is given in terms of two key controllable parameters: the amount of BCP swelling and solvent evaporation rate. Our results highlight the SVA mechanism for obtaining defect-free BCP thin films, as is highly desired in nanolithography and other industrial applications.