Boron ultra low energy (0.2-3 keV) implants in silicon have been characterized by a combined approach of secondary ion mass spectrometry (SIMS) and synchrotron radiation grazing incidence x-ray fluorescence (SR-GIXRF). SIMS analysis was carried out using ultra low energy O2+ beam in either fully or partially oxidizing conditions in order to identify the best approach. The rotation of the sample was applied to prevent or reduce the formation of roughness on the SIMS crater bottom and prevent strong variations of erosion rate. The resulting dose values were cross checked with the independently determined values from SRGIXRF analysis and revealed a good alignment between the techinques.