A method for depositing a metal layer on a wafer is disclosed. A PVD chamber is provide having therein a wafer chuck for holding a wafer to be processed, a target situated above the wafer chuck, a magnet positioned on a backside of the target, and a DC power supply for supplying a DC voltage to the target. The target is a metal or a metal alloy having ferromagnetism property. A paste process is performed to the PVD chamber. The paste process includes sequential steps of: admitting a working gas into the PVD chamber; and igniting the working gas in cascade stages. The wafer is then loaded into the PVD chamber and positioned onto the wafer chuck. A deposition process is then performed to deposit a metal layer sputtered from the target onto the wafer.