The Effect of Incident Cluster Ion Size on Secondary Ion Yields Produced from Si

Abstract

Secondary ions emitted from a Si target have been investigated under large Ar cluster ion bombardment. Incident ion beams with energies from 10 to 30 keV were used and the mean size of the Ar cluster ion beam was about 1000 atoms per cluster. Secondary Sin^+(n=1-11) ions were measured from Si under Ar cluster ion bombardment, while only atomic ions were measured under Ar monomer ion bombardment. In this study, we succeeded to accurately measure the incident size dependence of secondary ion spectra for Si under large Ar cluster ion bombardment using a time-of-flight technique combined a primary-ion beam deflector and a secondary-ion deflector. When the total incident ion energy was kept constant, the yields of secondary cluster ions such as Si6^+ relative to those of Si^+ increased with size. On the other hand, when the incident Ar cluster size was kept constant, the yields of secondary cluster ions relative to those of Si^+ decreased with energy. The effect of incident cluster size on secondary ion yields is discussed.