Profiles of High Conductivity Shallow Layers in Silicon Produced by Boron Ion Implantation

The conductivity profiles produced when boron ions are implanted into silicon have been investigated as a function of ion energy, total ion flux and annealing schedule. The bombardments were carried out in a manner such that channelling was minimized. These profiles have been compared with those predicted theoretically by Lindhard et al. (1963) for the bombardment of amorphous solids. At doping concentrations up to ∼10 18 acceptors/cm 3 the electrically active profile is in close agreement with the theoretical profile both as regards depth of the peak doping and the cut-off. At concentrations ≳ 10 20 /cm 3 there is slight modification of the back edge of the profile, presumably due to channelling. The conductivity produced by a given annealing schedule has been shown to be a function of the doping level and the results have been compared with those of Pavlov et al. (1965). The results show that this technique is capable of producing high conductivity layers with a very high degree of control of doping profile and junction depth.