SIMS using O ⁻ , F ⁻ , Cl ⁻ , Br ⁻ and I ⁻ primary ion bombardment

Abstract

The success of secondary ion mass spectrometry (SIMS) analyses depends largely on the ionization probability of the analyzed elements. The chemical state of the surface changes with the chemical nature and the concentration of implanted ions. The positive ionization probability can be enhanced by bombarding the surface with electronegative elements. In view of such an enhancement of the positive secondary ion yield, we present SIMS analyses carried out with O − , F − , Cl − , Br − and I − primary ion beams. Useful yields were experimentally determined for metal (Al, Ni, Cu, Ag and Ta) and semiconductor samples (Si, Ge, InP and GaAs). For metal samples, an enhancement of the useful yield under halogen bombardment, compared with O − bombardment, was observed for Ni, Cu and Ag under F − bombardment (enhancement of up to two orders of magnitude). For semiconductors, lower useful yields are obtained under halogen bombardment as compared with O − bombardment. The observed results are discussed in terms of the surface concentration of the implanted primary ion species and their electronegativity. Copyright © 2012 John Wiley & Sons, Ltd.