the invention relates to a method of forming a shallow junction . the method comprises forming source / drain extension regions with a non - amorphizing tail implant which is annealed conventionally and amorphizing implant which is re - grown epitaxially . the non - amorphizing tail implant is generally annealed before a doped amorphous layer for spe is formed . spe provides a high active dopant concentration in a shallow layer . the non - amorphizing tail implant expands the source / drain extension region beyond the range dictated by the spe - formed layer and keeps the depletion region of the p - n junction away from where end - of - range defects form during the spe process . thus , the spe - formed layer primarily determines the conductivity of the junction while the tail implant determines the location of the depletion region . end - of - range defects form , but are not in a position to cause significant reverse bias leakage .