A method and apparatus for performing post-exposure bake operations is described herein. The apparatus includes a plate stack and enables formation of a first high ion density plasma before the ion concentration within the first high ion density plasma is reduced using a diffuser to form a second low ion density plasma. The second low ion density plasma is an electron cloud or a dark plasma. An electric field is formed between a substrate support and the diffuser and through the second low ion density plasma during post-exposure bake of a substrate disposed on the substrate support. The second low ion density plasma electrically couples the substrate support and the diffuser during application of the electric field. The plate stack is equipped with power supplies and insulators to enable the formation or modification of a plasma within three regions of a process chamber.