Target: Referring to the material used as the cathode in the sputtering deposition system. Such cathode material separates from the cathode in the molecular, atomic or ionic form under impact by the positively charged and re-deposits on the surface of the anode. It can be divided into evaporation target, multi-arc target and sputtering target according to different deposition form. It can be divided into metal target, alloy target and ceramic target, etc. according to the different materials.