A new technique is proposed for the depth profiling of low energy As and P implants. We show that monitoring the monatomic negatively charged ions of As- and P-, using oxygen backfilling (flooding) in combination with low energy Cs+ sputtering, improves the sensitivity of SIMS profiling and removes the variation of the ion yield at the native oxide/silicon interface. (C) 2004 Elsevier B.V. All rights reserved.