Electrodeposition of Copper on Silicon from Sulfate Solution

In this paper, we report on the energetics and kinetics of copper deposition on n-type Si(100), Si(111), and miscut Si(111) surfaces from 1 mM solution. Electrochemical impedance spectroscopy showed that the position of the bandedges at the surface is very similar for n-Si(100), n-Si(111), and miscut n-Si(111) surfaces. At more positive potentials, the presence of electrically active surface states was observed. Cyclic voltammetry and current transients showed that copper deposition occurs by progressive nucleation and diffusion-limited growth for the three surfaces, which was confirmed by ex situ atomic force microscopy experiments. The rates for copper nucleation on Si(100) and Si(111) are essentially the same, while miscut Si(111) shows a slightly higher nucleation rate. These results indicate that the energetics and kinetics of copper deposition from acidic sulfate solution on silicon are essentially independent of the silicon surface orientation.