Oxygen precipitation in heavily boron-doped silicon

Abstract

Small-angle neutron scattering is used to study the precipitation behaviour of dissolved oxygen in dislocation-free Czochralski-grown single crystals of silicon doped with boron and compared with those for similar undoped material. The presence of boron dramatically alters the nature of precipitates in silicon. Heat treatment at 1023 K no longer leads to the formation of the large cushion-shaped precipitates observed in essentially undoped material. The precipitates are much smaller, and do not exhibit any anisotropic small-angle scattering. Furthermore, the precipitation process is over in less than 24 h. Subsequent treatment at 1323 K leads to the formation of cushion-shaped regions which are much larger than those formed in the absence of boron.