| abstract |
A plasma reactor for physical vapor deposition (PVD), also known as sputtering, which is adapted so that the atomic species sputtered from the target can self-sustain the plasma without the need of a working gas such as argon. The method is particularly useful for sputtering copper. According to the invention, a bias ring arranged around the wafer and rising above it is electrically biased to control the plasma potential, and hence to control the energy and directionality of the ions being sputter deposited on the wafer. The bias ring can be either a separate biasing element which can be positioned at a selected height above the wafer or a clamping ring clamping the wafer to the pedestal but having a biasing surface electrically insulated from the wafer and the pedestal. |