A method of fabricating an interconnect structure is described. A substrate is provided. A patterned interfacial metallic layer is formed on the substrate. An amorphous carbon insulating layer or a carbon-based insulating layer is formed covering the substrate and the interfacial metallic layer. A conductive carbon line or plug is formed in the amorphous carbon or carbon-based insulating layer electrically connected with the interfacial metallic layer. An interconnect structure is also described, including a substrate, a patterned interfacial metallic layer on the substrate, an amorphous carbon insulating layer or a carbon-based insulating layer on the substrate, and a conductive carbon line or plug disposed in the amorphous carbon or carbon-based insulating layer and electrically connected with the interfacial metallic layer.