Criteria for uniform thin film formation for polymeric materials

Design rules for the formation of high quality thin films generated from high molar mass polymer materials of the type used in electron beam lithography are critically considered. The variation of thickness of the spin coating deposited films with change in the concentration and spinning speed obeyed theoretical predictions. The quality of the films formed was assessed and found to depend on the value of the product of the intrinsic viscosity [η] and concentration c. The highest quality films were formed with [η]·c having a value of approximately 1. Higher values of [η]·c produced rough films at all spinning speeds; lower values of [η]·c generated films with the polymer predominantly deposited at the edges of the substrate and a high occurrence of voids and defects in the films. The molecular origins of the criteria for the optimum value of [η]·c for high quality films formation are discussed.