Formation and annealing of defects during high-temperature processing of ion-implanted epitaxial silicon: the role of dopant implants

We have investigated the optical and structural characteristics of defect e volution during high-temperature annealing of keV-ion-implanted epitaxial s ilicon using optical microscopy (OM), photoluminescence (PL) spectroscopy a nd transmission electron microscopy (TEM). Postimplantation annealing in ox ygen ambient resulted in oxidation-induced stacking faults (OISFs) and disl ocations. The PL spectrum of these samples is dominated primarily by a disl ocation-related D1 line, which is particularly strong in Al-implanted sampl es as a consequence of the enhanced formation of dislocations with Al impla ntation. Comparative analysis of the PL signature and OM observations of de fects for different implants suggests that D1 and D2 lines result from disl ocations rather than in the OISFs. Indeed, it is found that OISFs act as a nonradiative recombination channel in the luminescence of Si. PL studies of N-2-annealed samples indicate the formation of nonradiative defect centres . In the case of dopant implants, after rapid thermal annealing (RTA) for 2 min in N-2 ambient, the specific signature of extended defects was found f rom PL studies, while TEM analysis reveals the presence of < 111 > precipit ates located in a region with a high dislocation density. In comparison wit h other dopants, Al implants show an enhanced formation of extended defects , and they are found even at a depth beyond the end-of-ion range damage. (C ) 2000 Published by Elsevier Science S.A. All rights reserved.