Shallow P+ junctions have been fabricated using reverse-type dopant preamorphization by Sb. The junctions ∼100 nm in depth have leakage current below 10 nA/cm2, sheetresistance less than 200 Ω/□ and ideality factor in the range 1.01–1.03. This type of amorphization scheme provides electrical activation of B at low temperature, which is very promising for low temperature processing applications. The importance of process optimization was demonstrated. The electrical results were correlated with residual defect structure observed by cross-sectional TEM.