Semiconductor devices are formed with a silicide interface between the work function layer and polycrystalline silicon. Embodiments include forming a high-k/metal gate stack by: forming a high-k dielectric layer on a substrate, forming a work function metal layer on the high-k dielectric layer, forming a silicide on the work function metal layer, and forming a poly Si layer on the silicide. Embodiments include forming the silicide by: forming a reactive metal layer in situ on the work function layer, forming an a-Si layer in situ on the entire upper surface of the reactive metal layer, and annealing concurrently with forming the poly Si Layer.