We have developed a metallization method that successfully satisfies all the requirements for the next several generations of integrated circuits (ICs). This method was used to deposit fully conformal diffusion barriers of Ta and TaN as well as Cu seeding layers in 100-nm-wide trenches and vias with (depth:width) aspect ratios up to 8:1. The diffusion barrier and seeding layer are critical for the implementation of copper metallization schemes. This technique was also used to completely fill high aspect ratio trenches with copper. A fully ionized metal plasma deposition method is used in which the ion energy is varied and controlled as a function of time throughout the deposition process. No limitation of the process with respect to trench width or aspect ratio has been observed yet, suggesting the process can be used for ICs with sub-100 nm linewidths.