Metal-containing film etchant compositions may include hydrogen peroxide (H2O2), a phosphoric acid compound, a heterocyclic organic amine compound including at least one heteroatom in a ring, and water. Manufacturing methods of an integrated circuit (IC) may include performing a dry etch process on a conductive structure including a metal nitride film and a metal film to form a conductive pattern intermediate product and performing a wet etch process on the conductive pattern intermediate product using an etching atmosphere providing a higher etch selectivity with respect to the metal nitride film than the metal film. The etching atmosphere may include an etchant composition including hydrogen peroxide, a phosphoric acid compound, a heterocyclic organic amine compound including at least one heteroatom in a ring, and water.