Effect of oxygen on the formation of end-of-range disorder in implantation amorphized silicon

Formation of End-of-Range (EOR) disorder was studied in (100)-oriented silicon, when subjected to amorphization by implantation of Ge⁺ ions, followed by a 10 s Rapid Thermal Annealing (RTA) at 1050 °C. XTEM, RBS/channeling, and SIMS were used to analyze Czochralski grown (CZ) silicon wafers with oxygen concentrations of 6.5, 7.0, and 8.0 × 10¹⁷/cm³ and Float Zone (FZ) silicon, as “low oxygen” wafers. Amorphization on neighboring parts of the 4″ wafers was made either by 60 keV Ge⁺ implantation or by 110 keV Ge⁺ implantation and by sequential (60 keV + 110 keV) Ge⁺ implantation. Parts of each wafer were additionally implanted with 13 keV boron. In FZ silicon, no defects were found for 60 keV Ge⁺ implantation and RTA at 1050 °C. For 110 keV Ge⁺ and sequential (60 keV + 110 keV) Ge⁺ implantation in FZ-silicon the majority of the samples showed perfect annealing. Two wafers, however, subjected to sequential implantation still contained defects but with a defect density that was one order of magnitude lower than for CZ wafers. For one of them, not even a continuous layer of defects was formed. In contrast, CZ wafers contained defect bands, except for the 60 keV Ge⁺ implantation [in accord with the findings of Ozturk et al., IEEE Trans. on Electronic Dev. 35, 659 (1988)]. The presence of boron had no visible effect on the defect structure.