Effects of cetyltrimethylammonium bromide (CTAB) on electroplating twin-structured copper interconnects

Twin-structured copper possesses great potential in advanced interconnect electroplating because of high performance and high reliability. Whereas, the issue of surface nonuniformity restricts its practices in integrated circuits and demands a prompt solution. A novel additive strategy based on coexisting cetyltrimethylammonium bromide (CTAB) and gelatin is proposed and effects of CTAB to bath electrochemistry and material properties are investigated. With an optimum concentration of CTAB, the electroplating formular enables improved surface leveling and filling height coplanarity for twin-structured copper filling in 15/15µm line/space redistribution layer (RDL) patterns.