Copper Corrosion Issue Analysis and Study on Advanced CMP Process

As advanced semiconductor device features shrinking with each technology node, copper interconnect structures shows more importance effect because of the higher electrical conductivity and electro migration resistance of copper. Co /Ta/TaN novel metals are being introduced as barrier materials for advanced technology node. These types of materials enable cu filling of the narrowest structures and act as seed enhancement layers. However, it is difficult to solve the compatibility of the interconnect metals for copper chemical mechanical polishing process (CMP). Metal void and copper corrosion issues need to be controlled especially. The wet chemical environment in CMP process caused copper corrosion to be one of the critical issues for copper layer. This paper shows that by optimizing the copper CMP polish condition and cleaner condition has addressed the two types of copper corrosion, as copper chemical corrosion and galvanic corrosion. The failure analyses for how to identify the root causes and differentiate the corrosion have been discussed in details.