The impacts of the native oxides and the impurity loss mechanisms of low energy doping process for both p-type and n-type implants have been quantitatively studied using secondary ion mass spectrometry/angle-resolved x-ray photoelectron spectroscopy method. The low energy doping processes include conventional beamline implant and plasma immersion ion implantation (PIII). It has been found that the native oxides play very significant roles on the low energy implants, especially for PIII due to its unique impurity profiles. The results show very different behaviors on p-type and n-type implants because of the SiO2/Si interface segregation mechanisms. p-type (boron-based) doping loses more impurities into the native oxide, but n-type (arsenic-based) doping does not lose impurities. These results can be used to optimize the semiconductor processes such as implant, strip, clean, and thermal-annealing process.