Residual stresses in silicon and their evolution upon heat treatment and irradiation

Resumo

The distributions of internal stresses in undoped and tin-doped silicon and the influence of electron irradiation with an energy of 5 MeV and of heat treatment at 450°C on the stresses are studied. The stresses are measured by a method based on the detection of birefringence by modulation polarimetry. It is shown that tin-doped silicon includes stripes of point defects with a nonuniform distribution of residual stresses of up to 20 kg cm^–2. Heat treatment at 450°C induces an increase in the residual stresses in the sample to 50 kg cm^–2. It is established that the radiation defects formed upon the irradiation of tin-doped silicon reduce the residual stresses to 2–3 kg cm^–2.