The present invention relates to a semiconductor device and a fabricating method therefor. According to the semiconductor device of the present invention, a phased layer of under bump metallurgy (UBM) is formed by repeatedly depositing chrome and copper layers with sputtering equipment in which chrome and copper targets are installed in singular or plural chambers. The chrome and copper layers of the phased layer are deposited in the structure of the same, thin multi-layers possible for mutual diffusion, wherein the chrome layers gradually get thinner and the copper layers gradually get thicker. As a consequence, reliability in the phased layer of the present invention is achieved with increase in the speed of depositing UBM to reduce the time and cost for all the fabricating processes of the semiconductor device.