A method for manufacturing an SIP semiconductor device is provided. In this method, a first Organic Solderability Preservative (OSP) is coated over an upper surface of a semiconductor device including a plurality of elements and a first through electrode. An electrochemical plate (ECP) process is then performed on the semiconductor device. A second OSP is then coated over a lower surface of the semiconductor device, the lower surface including a Cu plug that has been formed over the first through electrode through the ECP process. The upper and lower (first and second) OSPs are used to prevent the Cu plug from being easily oxidized when exposed to the air.