The nucleation mechanism for oxidation–induced stacking faults in silicon crystals containing surface damage

Extrinsic stacking faults, generated during oxidation of (00l)–oriented silicon single-crystal wafers containing surface damage, have been found to nucleate by the dissociation of Lomer prismatio dislocations. Observations by transmission electron microscopy of unidirectionally abraded specimens, both in the as–abraded condition and after very short oxidation treatments, have confirmed the presence of Lomer dislocations at damage sites. Such dislocations dissociate very early during the oxidation treatment by a reaction that produces a Shcckley dislocation, which glides out of the crystal surface, and a Frank partial dislocation bounding an extrinsic stacking fault. The first experimental evidence obtained for this dissociation reaction is presented. The complete nucleation mechanism is discussed.