EVALUATION OF POLYENCAPSULATION, OXYGEN LEAK, AND LOW-ENERGY ION-BOMBARDMENT IN THE REDUCTION OF SECONDARY ION MASS-SPECTROMETRY SURFACE ION YIELD TRANSIENTS

The accurate determination of dopant concentrations in the near-surface region of secondary ion mass spectrometry (SIMS) depth profiles is often complicated by surface ion yield transients. These ion yield transients, which result mainly from the implantation of the ion yield enhancing primary ion beam, can lead to errors in the quantification of impurity species as well as distortions in the dopant profile shape. Polyencapsulation, oxygen flooding, and matrix normalization have each proven to be useful in the reduction and elimination of these surface ion yield transients. The use of low primary beam energies has been shown to have the additional benefit of reducing profile broadening due to cascade mixing. In this study, three methods of transient reduction were evaluated in the SIMS characterization of ultra-shallow p + junctions in Si (< 1000 angstrom) using oxygen bombardment and positive secondary ion detection.