Methods for depositing cobalt in features of a substrate include providing a substrate to a process chamber, the substrate having a first surface, a feature formed in the first surface comprising an opening defined by one or more sidewalls, a bottom surface, and upper corners, and the substrate having a first layer formed atop the first surface and the opening, wherein a thickness of the first layer is greater proximate the upper corners of the opening than at the sidewalls and bottom of the opening; exposing the substrate to a plasma formed from a silicon-containing gas to deposit a silicon layer predominantly onto a portion of the first layer atop the first surface of the substrate; and depositing a cobalt layer atop the substrate to fill the opening, wherein the silicon layer inhibits deposition of cobalt on the portion of the first layer atop the first surface of the substrate.