[en] Xe ions at energies from 50 to 350 keV, at increments of 50 keV, were implanted into Si₃N₄ films. The mean projected range and range straggling are measured by Rutherford backscattering using 2.1 MeV He ions. The longitudinal distribution parameters obtained are compared with our calculation procedure based on Biersack's angular diffusion model and Monte Carlo simulation (TRIM'89 code). Also the lateral spread of 100 keV Xe ions in SI₃N₄ film is obtained by means of implantation at tilted angles and Rutherford backscattering. The measured lateral spread is compared with TRIM'89. The result shows that the lateral spread of 100 keV Xe ions implanted in Si₃N₄ film is in good agreement with the TRIM'89 prediction within experimental error. (author)