Methods and apparatus for forming a metal silicide as nanowires for back-end interconnection structures for semiconductor applications are provided. In one embodiment, the method includes forming a metal silicide layer on a substrate by a chemical vapor deposition process or a physical vapor deposition process, thermal treating the metal silicide layer in a processing chamber, applying a microwave power in the processing chamber while thermal treating the metal silicide layer; and maintaining a substrate temperature less than 400 degrees Celsius while thermal treating the metal silicide layer. In another embodiment, a method includes supplying a deposition gas mixture including at least a metal containing precursor and a reacting gas on a surface of a substrate, forming a plasma in the presence of the deposition gas mixture by exposure to microwave power, exposing the plasma to light radiation, and forming a metal silicide layer on the substrate from the deposition gas.