The invention includes a method of forming a metal-containing film over a surface of a semiconductor substrate. The surface is exposed to a supercritical fluid. The supercritical fluid has H.sub.2, at least one H.sub.2-activating catalyst, and at least one metal-containing precursor dispersed therein. A metal-containing film is formed across the surface of the semiconductor substrate from metal of the at least one metal-containing precursor. The invention also includes semiconductor constructions having metal-containing layers which include one or more of copper, cobalt, gold and nickel in combination with one or more of palladium, platinum, iridium, rhodium and ruthenium.