A non-planar semiconductor transistor device includes a substrate layer. Conductive channels extend between corresponding source and drain electrodes. A gate stack extending in a direction perpendicular to the conductive channels crosses over the plurality of conductive channels. The gate stack includes a dielectric layer running along the substrate and the plurality of conductive channels and arranged with a substantially uniform layer thickness, a work-function electrode layer covers the dielectric layer and is arranged with a substantially uniform layer thickness, and a metal layer, distinct from the work-function electrode layer, covers the work-function electrode layer and is arranged with a substantially uniform height with respect to the substrate such that the metal layer fills a gap between proximate conductive channels of the plurality of conductive channels.