"Lateral secondary ion mass spectrometry (SIMS)" has been demonstrated to be capable, within certain limits, of measuring the lateral straggle and diffusion of dopants under mask edges. In the present work measurements of lateral dose distributions of arsenic and boron in silicon are presented and discussed, and information on the error margins of the method derived. It is shown that the lateral dose distribution of arsenic and boron can be measured down to dose levels of 5 x 10(12) cm(-2) and 2.6 x 10(13) cm(-2), respectively. In repeated measurements, the profile shapes have been reproduced to within a few nanometers, and the profile position relative to the mask edge determined with about +/-10 nm error, It is this rather high degree of accuracy that allows Lateral SIMS data to be of value in the calibration and validation of two-dimensional process simulators. An example is given showing the correlation between IMSIL (Technical University Vienna) simulation and experimental data for an as-implanted sample. By comparing experimental data from samples after dopant diffusion and at several topography variants with TMA SUPREM4 simulation, it is shown that an accurate determination of the topography of the implant window in the vicinity of the mask edge is an essential prerequisite of any simulator calibration.