Solvent vapor annealing (SVA) is a widely used technique for controlling the morphology and ordering of block copolymer (BCP) films. By controlling the block ratio (f = N/N), spheres, cylinders, gyroids , and lamellae structures can be generated by forming a swollen and mobile layer of thin-film from added solvent vapor to facilitate the self-assembly of the polymer blocks. The process allows increased lateral ordering by several magnitudes to previous methods. It is a more mild alternative to thermal annealing.
Ideally, the chamber in which SVA takes place is a metal chamber that is inert to reaction with the given solvent, allowing for high precision in forming the desired nanostructures. Computers with designed program control of the valves for solvent addition and withdrawal are used to increase precision as well. This regulated inlet along with close monitoring of pressure gauges and thickness allows instant response and control while the annealing and evaporation phases precede.