Stacking fault nucleation in epitaxial silicon on variously oriented silicon substrates

Abstract

Epitaxial growth of silicon is studied for seven low-index orientations of the silicon substrate. Stacking fault traces are observed on all growths in both the single line and polygonal forms, the latter being dominant in the better growths. For each orientation the largest uniform size stacking fault polyhedra nucleate on the substrate surface and have traces on the film surface with dimensions directly related to the film thickness through a geometric factor. This factor is computed by taking the bounds of the faults (which lie in {111} planes) as 〈110〉 directions. Direct observations are presented to show that stacking faults form at slip lines, at microscratches produced in the polishing procedure, at particles on the substrate surface, at regions of localized impurity segregation, at surface oxides, and at cleaning stains. Most of the faults can be removed by annealing in hydrogen but not in argon. Among mechanically polished substrates, {111} substrates have the highest stacking fault density. No orientation effect is observed for growths on chemically polished substrates. The effects are consistent with nucleation by small incorrectly deposited two-dimensional layers and by the presence of a foreign substance (probably an oxide) on the substrate surface; the model attributing stacking fault nuclei to collapsed vacancy disks is highly unlikely. © 1964 The American Institute of Physics.