Films consisting of multiple layers are readily deposited using different cathode materials—copper, tantalum, tantalum nitride, and a variety of other materials can be applied in this way. Copper metalization, for example, may begin by depositing a conformal film of tantalum 20 to 50 nanometers thick. Ions of copper are then deposited on top of the tantalum layer. The process can be halted when the new material has formed a thin conformal coating, or deposition can be continued until the trench is filled completely. Another possibility is to use the thin copper layer as a "seed layer" and fill the trench electrochemically.