Devices and methods of fabricating integrated circuit devices via cobalt fill metallization are provided. A method includes, for instance, providing an intermediate semiconductor device having at least one trench, forming at least one layer of semiconductor material on the device, depositing a first cobalt (Co) layer on the second layer, and performing an anneal reflow process on the device. Also provided are intermediate semiconductor devices. An intermediate semiconductor device includes, for instance, at least one trench formed within the device, the trench having a bottom portion and sidewalls, at least one layer of semiconductor material disposed on the device, a first cobalt (Co) layer disposed on the at least one layer of semiconductor material, wherein the at least one layer of semiconductor material includes at least a first semiconductor material and a second semiconductor material.