Seedless Fill-Up of the Damascene Structure Only by Copper Electroless Plating

We attempted to fill up seedlessly the damascene pattern in ULSI interconnection only by Cu electroless plating. Cu 2 O content, which was generally detected in Cu electroless plating, was removed through controlling the plating temperature. Optimum control in electrolyte concentration and plating temperature leaded to good characteristics of electrolessly plated Cu with 2.1 µΩ·cm resistivity, 8.9 nm rms roughness at 160 nm thickness, good adhesion and 10 nm/min deposition rate. The optimum condition was successfully applied to a damascene pattern with aspect ratio of 3 and via size of 0.13 µm without void and seam.