A method of manufacturing a semiconductor device and an apparatus for manufacturing a semiconductor device in which moisture is removed from a porous low-dielectric layer after a chemical mechanical polishing (CMP) process include formation of a porous low-dielectric layer on a substrate. A metal interconnection is formed on the substrate having the porous low-dielectric layer. The metal interconnection forms a planar surface with the porous low-dielectric layer to fill the openings. Ultraviolet (UV) light is irradiated to the porous low-dielectric layer to remove absorbed moisture from the porous low-dielectric layer. A capping layer is formed on the substrate having the porous low-dielectric layer and the metal interconnection. The capping layer is formed in-situ to prevent additional absorption of moisture.