Comparative investigations were performed using high-depth-resolution Rutherford backscattering (RBS) combined with channeling, spectroellipsometry (SE) and atomic force microscopy (AFM) to analyze surface disorder and surface roughness formed during plasma. immersion implantation of silicon (100) substrates in a gas mixture containing PH3. In order to enhance the sensitivity to the determination of the oxygen content of the surface oxide layer, the 3.05 MeV (He-4(+), He-4(+)) nuclear resonance was used in combination with channeling. For the analysis of SE data we used the method in which an appropriate optical model is assumed and a best fit to the model parameters is obtained (i.e. the thickness of surface oxide and damaged silicon lavers and the volume fraction of the components). Evaluation of RES spectra yields damage profiles consistent with those obtained by SE modelling.