Stacking fault pyramid formation and energetics in silicon-on-insulator material formed by multiple cycles of oxygen implantation and annealing

The defect microstructure of silicon-on-insulator wafers produced by multiple cycles of oxygen implantation and annealing was studied with transmission electron microscopy. The dominant defects are stacking fault pyramids (SFPs), 30-100 nm wide, located at the upper buried oxide interface at a density of ∼10⁶ cm^-2. The defects are produced by the expansion and interaction of narrow stacking fault (NSF) ribbons pinned to residual precipitates in the top silicon layer. Consideration of the energetics of the transformation from a collection of four NSF ribbons to a single SFP indicates that the reaction is energetically favorable below a critical NSF length. Thus small defects are stable as SFPs while large defects are stable as NSF ribbons.