Silicon self-interstitial cluster formation and dissolution in SOI

Abstract

Silicon-on-insulator (SOI) is a promising alternative to bulk silicon as ultra shallow junction depths have begun to shrink below 50 nm. This study examined the effect of the SOI surface silicon/buried oxide interface on {311} defect evolution after Si+ ion implantation. SOI wafers were produced such that the surface silicon thickness varied from 300Å to 1600Å. Non-amorphizing Si+ implants at 5 and 20 kev with a dose of 2×1014 cm-2 were performed into SOITEC SOI wafers. Furnace anneals were done at 750°C from 5 minutes to 4 hours and quantitative transmission electron microscopy (QTEM) was used to study the implant damage evolution. At 5 keV, the dissolution behavior of the SOI was very similar to that of the bulk. However, the extended defects in the 300 Å SOI did not nucleate the same as those observed in the bulk or thicker SOI. Similar results were seen at 20 kev for the 700 Å SOI, but a slight decrease in the concentration of trapped interstitials was observed due to interface recombination as a result of the increased projected range of the implant. It is concluded that the surface Si/BOX interface does not significantly affect recombination of interstitials trapped in extended defects unless the interstitial profile is close to or truncates the interface. However, the interface does appear to affect the stability of zig-zag {311} defects and dislocation loops in thin SOI at lower implant energies.