Copper interconnects in microchips are currently formed by Cu
electrodeposition. With the trend of future device miniaturization, the copper interconnect dimensions will shrink, requiring a drastic change in the current state-of-the-art interconnect metallization process. The major technology hurdles include: i) non-uniformity of Cu seed layer deposited by physical vapor deposition (PVD) on the barrier and ii) deteriorated electromigration resistance of Cu interconnects. A technology under development relies on vapor deposition of a uniform ruthenium (Ru) layer on the barrier, followed by electroless deposition of a thin and continuous Cu seed layer on Ru.
In this thesis, we report an electroless bath that enables deposition of copper-manganese (Cu-Mn) alloy film. Incorporating Mn with Cu is attractive due to ability of Mn to improve Cu's electromigration resistance. Results show the Mn incorporated is mobile, a requisite for its application in interconnect metallization. Electrochemical and Quartz Crystal Microbalance (QCM) measurements indicate that the mechanism of Mn incorporation during electroless Cu deposition is most likely the underpotential deposition of Mn on Cu.