It has become more important to get the real depth profile of boron at the shallow region in the silicon wafer. We have been studying dual ion beam technique, which uses both low energy oxygen ion beam for surface oxidation and Cs ion beam for sputtering, in order to extract the real distribution of the certain element exists around the SiO2/Si interface. In this study, SIMS sensitivity change of the implanted boron into silicon taken by dual ion beam technique through the oxidation process, is discussed as compared with conventional SIMS. As the results, dual ion beam technique can fully eliminate the matrix effect, which brings the difference of the oxidation states between SiO2 and Si substrate. The effect of the surface composition on the secondary ion efficiency by means of estimating the surface concentration at the craters, which are formed under dual ion beam, and a conventional SIMS, are discussed. (C) 2002 Elsevier Science B.V. All rights reserved.