Method for forming metal structure in semiconductor device, and manufacturing method for interconnection layer

The invention discloses a method for forming a metal structure in a semiconductor device, and a manufacturing method for an interconnection layer. The method for forming the metal structure in the semiconductor device comprises the steps: employing one-time or repeated electroplating to forming the metal structure, wherein the additive of electroplate liquid used at one time is an inorganic additive. The method not only prevents organic residues from being generated in a process of forming the metal structure when the electroplate liquid taking the inorganic additive as the additive is employed, and but also can fill a hole generated in the metal structure in the electroplating process, thereby reducing the defects generated in the metal structure, and improving the stability of the semiconductor device.