Annealing characteristics of highly doped ion implanted phosphorus layers in silicon

Abstract

Abstract A combination of sheet resistance, stripping and Hall effect measurements have been made on phosphorus layers implanted into silicon at 40 and 100 keV with doses between 1 × 1015 and 5 × 1016 atoms/cm2. The implants were made at room temperature and 450°C. After annealing at 650°C, the profile of electrically active phosphorus following a high dose room temperature implant, was found to be flat topped with a concentration of approximately 5 × 1020/cm3. Very little diffusion occurred when annealing to 850°C where the free electron concentration increased to approximately 1.5 × 1021/cm3. Highly doped channeled tails were found when implanting at 450°C along the 〈110〉 direction and damage was being continuously annealed out preventing the formation of an amorphous phase. The rapid diffusion of the profile into the bulk found when annealing between 650°C and 850°C was speculated to be due to the presence of a dense dislocation entanglement in these layers following a hot implant.