Investigations on Ru-Mn films as plateable Cu diffusion barriers

In this study Ru-Mn alloys are discussed in terms of some of the major questions that are typically associated with the development of new types of barriers. First, the Cu diffusion barrier performance after annealing at high temperatures and under subsequent bias temperature stress is investigated, on SiO₂ and on low-k dielectrics. Second, the origin of the barrier performance - either a self forming barrier caused by segregation of an alloyed element, or the stuffing of grain boundaries - is investigated, since this is of importance with regard to an electromigration barrier at the bottom of a via. Third, Cu plating and Cu adhesion behavior are addressed, since they are also important with regard to electromigration, specifically along the side walls of trenches. Fourth, the blocking of oxygen diffusion is investigated. Furthermore, down-scaling of the Mn content to a lowest possible level is pursued in order to reduce line and via resistances.