Electrochemical Deposition of Copper onto Silicon

摘要

The open-circuit deposition of copper onto silicon rotating disks has been studied to determine the deposition mechanism and the effects of deposition conditions on the properties of the resulting copper films. Cu~(2+) reduction limits the rate when HF is present in large excess, and Si oxidation and dissolution limit the rate at lower ratios of [HF] to [CuSO_4]. The rate-limiting process strongly affects the resulting film properties, as the Cu films are smoother and more reflective when Cu~(2+) reduction limits the rate. Deposition rates increased with increasing rotating speed, and Cu~(2+) was found to be the diffusion-limited species over a wide range of CuSO_4 (0.001-0.04 M) and HF (0.02-0.4 M) concentrations. Open circuit potential measurements confirmed that Cu~(2+) was the species responsible for diffusion limitations through the external boundary layer.