Two-dimensional BMD, BSF, ring-OISF and COP distributions in a dislocation-free ingot grown by the NOC method

Abstract

The noncontact crucible (NOC) method has a large and deep low-temperature region in Si melt to grow a uniform large Si single ingot. The theoretical simulation pointed out that the lowest vacancy or interstitial Si atom area appears in the region with the smaller ratio between temperature gradients at melt surface and growing interface. The growth condition to obtain this region is suitable for the NOC method. The quality of a NOC ingot was first evaluated by determining the distribution of bulk micro defect (BMD), bulk stacking fault (BSF), oxidation induced stacking fault (OISF) and crystal originated particle (COP) in the cross section of the dislocation-free ingot. A ring-OISF or BSF can be clearly observed on the cross section cut from the middle and tail parts of the ingot. BMD can be observed inside and outside the ring-OISF. By estimated comparison to the none-doping case, CV (=CI) at cross point clearly has a trend to increase for the high B-doing case (5 × 1019 cm−3), where CV and CI are concentration of vacancy and interstitial Si atom, respectively. Nevertheless, in comparison with the distribution of COP in Cz and NOC ingots, COP cannot be detected inside the ring-OISF in the NOC wafer under the same etching process as many COP can be observed in the Cz wafer. This may be a unique feature for NOC growth.