Method of production of homogeneously doped silicium monocrystals with n-conductivity and adjustable doping material concentration by neutron irradiation

In producing, e.g., power semiconductor components with high reverse voltage rating from silicon monocrystals, especially in a zone melting process, their radial and axial concentration of doping material is changed. In order to rehomogenize the monocrystals of p-type or n-type conducting material, they are submitted to radioactive doping according to the reaction 30Si(n,γ)31Si → 31P. Irradiation of the silicon monocrystals with thermal neutrons is carried out until the desired n-type doping concentration is reached. This is the case when the concentration of the produced phosphorus atoms is at least a factor of two higher than the concentration of foreign material in the initial material. If a concentration of n-type doping material is to be set up with p-type conducting initial material, neutralization is first achieved with the production of phosphorus atoms, followed by controlled neutron doping. (DG/PB)