Embodiments comprise forming a stacked arrangement of layers, the stacked arrangement of layers comprising an additive layer on a substrate, and a metal layer on the additive layer, annealing the stacked arrangement of layers to form a metal silicide layer on the substrate, wherein the metal silicide layer includes an additive from the additive layer. Alternative embodiments include etching the stacked arrangement of layers to remove an unreacted material layer. In an alternative embodiment, the stacked arrangement of layer comprises a metal layer on a substrate, an additive layer on the metal layer, and an optional oxygen barrier layer on the additive layer. An annealing process forms a metal silicide containing an additive. Metal silicides formed according to embodiments are particularly resistant to agglomeration during high temperature processing.