Copper corrosion issue and analysis on copper damascene process

As semiconductor device features shrink into deep-submicron regime, copper metallization is taking the place of aluminum (Al)-tungsten (W) metallization because of the higher electrical conductivity and electromigration resistance of copper. However, it is very difficult for copper to be etched by dry etching method, thus copper metallization is created with damascene process. In this process, chemical mechanical polishing (CMP) is the key step. The wet chemical treatment in CMP makes copper corrosion to be one of the critical issues for copper metallization. This paper has addressed the three different types of copper corrosion, namely copper chemical corrosion, copper galvanic corrosion and photo assistant copper corrosion. The failure analyses for how to differentiate them and identify their root causes have been also discussed in details.