For deep submicron technologies it is of crucial importance to grow ultra-thin (<3-4 nm) dielectrica with extreme quality and uniformity. It has been shown that the growth mode of these films (layer by layer versus island like) has a dramatic impact on the further integration with polysilicon and the electrical performance of the high k stack. Since a large number of process parameters need to be investigated, a rapid diagnostic tool for determining the growth mode is required. We show, based on a comparison between LEIS, XPS, and TOF-SIMS that TOF-SIMS surface spectra can be used to probe the layer structure (in particular for the detection of island growth). For this purpose, we have examined ZrO2/Si stacks grown by ALCVD for which it has already been reported that ZrO2 grows on HF-etched Si surfaces in an island growth mode. We have studied the possible matrix effects which could hamper the TOF-SIMS data interpretation and show that it is (fairly easily) possible to distinguish between different growth modes for ZrO2. (C) 2002 Elsevier Science B.V. All rights reserved.