The lateral spread of implanted31P and11B ions into Si has been measured using ion implantation at oblique incidence and theC‐Vmethod. Standard deviations of the lateral spread are 570 and 825 Å for 145‐keV and 260‐keV31P ions, respectively, and 725 and 1100 Å for 80‐keV and 150‐keV11B ions, respectively. These results are in good agreement with the theoretical values in the literature.