Methods for forming an interconnections structure on a substrate in a cluster processing system and thermal processing such interconnections structure are provided. In one embodiment, a method for a device structure for semiconductor devices includes forming a barrier layer in an opening formed in a material layer disposed on a substrate, forming an interface layer on the barrier layer, forming a gap filling layer on the interface layer, and performing an annealing process on the substrate, wherein the annealing process is performed at a pressure range greater than 5 bar.