DEVELOPMENT OF IONIZED CLUSTER BEAM SOURCE FOR PRACTICAL USE

Low-energy ion bombardment during film growth can significantly modify film properties. The practical advantages of using an ionized cluster beam (ICB) include reduced damages and high deposition rates at low temperature. The design and the characteristics of the ICB source are described. The ionized cluster trajectories and the potential profiles were numerically calculated in order to optimize the design. The ionization chamber has restrictive electrodes to enhance the ionization probability in the low cluster density region near the anode. With these electrodes, the source provides uniform ion current densities up to 30 μA/cm2 at voltages ranging from 200 to 8000 V over a 127 mm diam substrate at a distance of 300 mm from the source. The ICB source can operate over a wide temperature range up to 2000 °C. Deposition rates up to 120 nm/min are obtained for Ti, Si, and Cu. The source has successfully operated for more than 100 h in several industrial applications.