Method for forming interconnect structure

Abstract

An improved interconnect structure and a method for forming the interconnect structure is disclosed that allows the interconnect structure to achieve a lower Rc. To lower the Rc of the interconnect structure, an α-phase inducing metal layer is introduced on a first Ta barrier layer of β phase to induce the subsequent deposition of Ta thereon into the formation of an α-phase Ta barrier layer. The subsequently deposited Ta barrier layer with a primary crystallographic structure of α phase has a lower Rc than that of the β-phase Ta barrier layer.