The effect of oxygen on secondary defect formation in MeV self-implanted silicon

Abstract

The effects of ion fluence and oxygen concentration on secondary defect formation in MeV self-implanted silicon has been studied for Czochralski (Cz) and float zone (FZ) wafers by means of transmission electron microscopy (TEM) and optical microscopy with bevel polishing/chemical etching. We found that the density, distribution and number of extended defects is strongly dependent upon the oxygen concentration. The dislocation density was found to be up to one order of magnitude lower in FZ wafers. At high ion fluences (∼ 10 15 cm −2), secondary defects form in a well-defined band near the ion projected range, R p. At lower ion fluences, dislocations extend from the defect band to increasingly large depths. For ion fluences approaching the threshold for secondary defect formation (∼ 10 14 cm −2), defects are observed from the surface to depths of ⋍ 10 μm, i.e., five times R p.