Fast Neutral Ar Penetration during Gas Cluster Ion Beam Irradiation into Magnetic Thin Films

ABSTRACTAr penetration during gas cluster ion beam (GCIB) irradiation has been investigated using secondary ion mass spectroscopy (SIMS). The concentration of Ar rose to a maximum and then decreased gradually with increasing depth. The depth of the Ar penetration peak increased in proportion to the cube root of the acceleration voltage of GCIB and was independent of ion dose. Ar penetration was attributed to fast neutrals in the GCIB and was successfully suppressed by decreasing the pressure of the space downstream of the GCIB or decreasing the monomer ion density in order to suppress charge transfer collisions.