Secondary ion mass spectrometry (SIMS) with gas cluster ion beams (GCIB) was studied with experiments and molecular dynamics (MD) simulations to achieve a high-resolution depth profiling. From MD simulations of Ar cluster ion impact on a Si substrate, the ion beam mixing by a cluster ion was heavier than that by Ar+ at the same energy per atom, because the energy density at the impact point by clusters was extremely high. However, the sputtering yield with an Ar cluster ion was one or two orders of magnitude higher than that with Ar+ at the same energy per atom. Comparing at the ion energy where the altered layer thickness was the same by both Ar cluster and Ar+ impact, a cluster ion showed almost 10 times higher sputtering yield than Ar+. Preliminary experiment was performed with a conventional SIMS detector and a mass resolution of several nanometer was achieved with Ar cluster ions as a primary ion beam. (C) 2002 Elsevier Science B.V. All rights reserved.