Diffusion and outdiffusion of aluminium implanted into silicon

The diffusion of aluminium in single-crystal silicon has been studied in the temperature range 1000-1290 degrees C. A low implantation dose (1*10 14 Al cm -2 ) was used to avoid dopant precipitation and a high energy (6.0 MeV) to reduce the influence, if any, of the surface. The experimental profiles, measured by spreading resistance, have been fitted taking into account the escape of Al from the Si surface into the ambient atmosphere. A pre-exponential value of 8.88 cm 2 s -1 and an activation energy of 3.44 eV have been found in this experiment. When aluminium is implanted through a capping layer, a reduction of the residual amount has been observed at medium energy (300 keV), while no difference has been measured at high energy (6 MeV).