GAS CLUSTER ION BEAM SOURCE FOR SECONDARY ION EMISSION MEASUREMENTS

摘要

Large argon and oxygen clusters with mean size of 3000 were bombarded on silicon targets at low energies (0～18keV), and secondary ion yield were measured. The cluster beams were produced by a Gas Cluster Ion Beam Source (GCIB) developed at Kyoto University. Secondary ion yield as a function of primary beam energy were compared for monomer and cluster impacts. For monomer impacts the emission of ionized species has similarities with the emission of neutral species, while for cluster impacts, secondary ion yield increases nearly in an exponential function. This result indicates that the mechanism of secondary ion emission by cluster ions is totally different from that of monomer ions. The use of cluster projectiles is efficient in producing secondary ions from target surface.