IMPURITY EFFECTS ON OXYGEN PRECIPITATION INDUCED BY MEV IMPLANTS IN CZ SILICON

The heterogeneous precipitation of oxygen in Cz silicon wafers has bee n investigated for the following implanted ions: Al, C, Si, P, and As, after anneal in the 800-1200 degrees C temperature range. The amount of precipitated oxygen, as measured by secondary ion mass spectrometry , ranges from 7 X 10(13) (As implant) to 3 X 10(14) cm(-2) (Al implant ) after an anneal at 1000 degrees C for 20 min. The residual damage, a s detected by transmission electron microscopy, does not show a signif icant dependence on the amount of precipitated oxygen as demonstrated by the analysis of Cz and epitaxial silicon wafers. The results are ex plained in terms of the interstitial trapping by species like C and Al , that enhances the heterogeneous formation of SixOy clusters. The sub sequent growth of precipitates has been modelled for Al and C implants and for several annealing temperatures and times.