Abstract Surface profile and Auger electron spectrometry measurements were used to monitor the swelling and sputtering of oxide layers formed by 40 keV 16O 2 + ion implantation of single-crystal silicon samples (all doses below are given for O + ions). As the implanted dose increases, the surface level of the implanted region rises with respect to that of the non-implanted region. This rise is found to be due to swelling, probably resulting from oxidation. For a dose of 2.5 × 1 o 17 cm −2 the maximum positive displacement of 30 nm is registered. For still higher doses the implanted surface level falls. After annealing, a layer shrinkage of about 10% in oxide layers formed by ion implantation was measured.