Extended defects in silicon by MeV B++ implantation in different 8" Cz-Si wafers

High-energy ion implantation is being increasingly implemented in device manufacturing for well and buried layer formation. The results of a detailed experimental comparison of different 200 mm silicon substrates after MeV B++ implantation are reported. Special emphasis was put on engineering the “good for device” quality of the implanted layer. The influence of various implant parameters (energy, dose) and substrate parameters (dissolved and precipitated oxygen, pulling conditions, wafer backside) on secondary defect generation were investigated. Chemical defect etching techniques, TEM and various electrical tests (generation lifetime, gate oxide integrity) were used for characterization. With increasing boron dose, the dislocation size in the R_p-region decreases while the density increases. This yields a very low near surface defect density and outstanding electrical properties in the high dose regime, The implant energy is of much less influence. Precipitated oxygen in the bulk of the substrate (i.e. internal gettering) is very effective at reducing implant damage and therefore increasing lifetime and gate oxide integrity in the low dose regime. The formation of an oxygen denuded zone is effective at avoiding extended threading dislocations in the high dose regime. This is explained by a dislocation pinning effect and by a strong oxygen pileup in the R_p-region. The oxygen pileup can be avoided by reducing the dose or by a suitable thermal treatment of the substrate prior to the implantation