Hole mobility degradation has been studied in high-dose boron-implanted ultrashallow junctions containing high concentrations of boron-interstitial clusters BICs, combining an empirical method based on the self-consistent interpretation of secondary-ion-mass spectrometry SIMS and Hall measurements and liquid-nitrogen LN 2 to room temperature RT hole mobility measurements. It has been found that BICs act as independent scattering centers which have a strong impact on hole mobility in addition to the other scattering mechanisms such as lattice and impurities scattering. A mobility degradation coefficient has been introduced, which gives information on the mobility degradation level in the analyzed junctions. In the case of very high concentrations of BICs containing a boron density up to 8 10 14 cm −2 , measured hole mobilities were found to be 40% lower than corresponding theoretical values. BICs dissolution through multiple Flash anneals at high temperature 1300 ° C reduces the observe mobility degradation.