Development of in situ studies of spin coated polymer films

High quality, uniform thin polymer films are routinely produced by the technique of spin coating. Applications for such polymer films beyond photoresist layer fabrication include photovoltaics and light-emitting diodes, where device performance is dependent upon an appropriate phase separated morphology. Developing an understanding of the factors involved in the development of such morphologies is therefore an important goal. The spin coating of polymer blends is a high speed, non-equilibrium process and as such, it is difficult to monitor in situ, with most studies inferring structure development from the resultant final morphology. Over the past 20 years various in situ experimental techniques have been developed, providing insight into the details of the spin coating process itself and opening a route to understanding and controlling morphological development. The majority of studies have been based upon interferometry and light scattering, "based in reciprocal space" and have been able to verify theoretical models of spin coating and the associated phase separation of polymer blends, with direct real-space, in situ studies now a possibility.