Effect of Halides on MPS Orientation and Cu Deposition Rates at Cu Surfaces

Abstract

Surface enhanced Raman spectroscopy (SERS), electrochemical measurements, and contact angles were used to evaluate the effect of halides on Cu electrodeposition rates in the presence of 3-mercapto-1-propanesulfonate (MPS). The Cu(II) reduction rate was shown to decrease in the order Cl− > Br− > I−. In-situ SERS and contact angle measurements showed that adsorbed MPS will exhibit decreased gauche to trans (g:t) ratio and decreased hydrophobicity in the same order as the Cu(II) reduction rate. The amount of MPS in the gauche form, due to the hydrophobicity of the halide decorated surface, is a key factor in the Cu(II) reduction rate in acid sulfate baths containing the accelerator.