Silicon-on-insulator (SOI) is important for VLSI and three-dimensional integrated circuits. An SOI sample fabricated by Separation by IMplanted Oxygen and Nitrogen (SIMON) was depth profiled by dual beam TOF-SIMS. The sputter and analysis beam were 1 keV Cs+ and 10 keV Ar+, respectively. The matrix effects were pronounced during the depth profiling,,when the atomic secondary silicon ion was used. The intensities of the detected secondary ions were related to the cesium coverage on the surface. However, the depth distribution in this sample was characterized by the proper selection of the atomic and cluster secondary ions. Some useful information about this sample including trace contamination has been obtained. (C) 2002 Elsevier Science B.V. All rights reserved.