Development of 1Â mA cluster ion beam source

High ion dose is needed to realize the nano-level smoothing and etching of hard materials using cluster ion beam. Large current is needed to increase the productivity of processing. In order to get the large current cluster ion beam, the cluster generator, ionizer and ion extraction has been studied. The intensity of neutral beams generated from various shapes of nozzles was measured and the orifice diameter of skimmer was adjusted. As a result, the 10 times stronger neutral beams could be generated and a maximum beam current of 2.4 mA was achieved at the acceleration voltage of 45 kV with the source gas pressure of 15,000 Torr. The ratio of monomer ion in the beam was 58%. This result indicates that the beam current of cluster ion except monomer ion is about 1 mA. With this beam current, 12-in. wafers can be treated with 2 × 1015 ions/cm2 in about 4 min. The process speed is high enough so that the cluster beam is available for next generation processes.