ECD therefore requires an electrically conducting surface, and ALD is often used to make a seed layer for the ECD process. While ECD has become the most widely used method for Cu deposition for interconnects due to its ability to deposit highly conformal films with excellent step coverage in high-aspect-ratio structures, wet-chemical techniques cannot be easily integrated in vacuum-cluster tools. ECD is also associated with the generation of large volumes of wastewater contaminated with metal ions that must be managed. A transition from wet-chemical electrodeposition to vacuum-based techniques is therefore desired.