Effect of Ni on Electroless Cu Plating Rates in the Presence of 2,2′-Bipyridyl and 2-Mercaptobenzothiazole

Electrochemical measurements and Surface Enhanced Raman Spectroscopy (SERS) are used to evaluate the effect of Ni addition on the rate of Cu electroless deposition in the presence of 2,2′-bipyridyl (BP) and 2-mercaptobenzothiazole (MBT). Ni addition is found to increase the rate of electroless Cu deposition in the presence of BP but had no effect on the rate in the presence of MBT. In situ SERS obtained at the potential of electroless deposition shows that BP is destabilized from the Cu surface in the presence of Ni, likely due to the increased positive charge present with Ni-incorporated Cu. The BP deficient surface exhibits a higher electroless deposition rate relative to a surface with substantial BP. In contrast, SERS shows that Ni addition does not alter MBT adsorption to Cu, due to the increased affinity of MBT to the electrode surface relative to BP.