ETCHANT FOR ETCHING A COBALT-CONTAINING MEMBER IN A SEMICONDUCTOR STRUCTURE AND METHOD OF ETCHING A COBALT-CONTAINING MEMBER IN A SEMICONDUCTOR STRUCTURE

An etchant for etching a cobalt-containing member in a semiconductor structure includes a fluorine-free acid and an alkaline solution, a rate of etching a cobalt-containing member by the etchant is greater than a rate of etching a nitride-containing member by the etchant, and a level of dissolved oxygen of the etchant is less than or equal to 100 ppb. A semiconductor structure, includes a plurality of epitaxial structures over a substrate, a gate structure over the substrate and between two of the plurality of epitaxial structures; a cobalt-containing member over one of the epitaxial structures and adjacent to the gate structure; and a dielectric member over the cobalt-containing member, wherein a top surface of the cobalt-containing member is formed by etching a portion of the cobalt-containing member using an etchant including a fluorine-free acid and an alkaline solution.