This paper presents strong evidence for carbon and oxygen gettering during high dose implantation of Cr and Al into Si by implanted ions or Si atoms. Rutherford Backscattering (RBS) and Auger Electron Spectroscopy (AES) experiments of Cr and Al implanted Si samples in a diffusion pumped vacuum (DPV) system (≃ 10−6 Torr) clearly indicate that the incorporation of carbon or oxygen occurs preferentially and depends on the surface composition which is controlled by the dose of implantation and by sputteripg.
The implantation of Cr and Al in a DPV system (≃ 10−6 Torr) results in a large increase in the concentration and retention of implanted atoms compared to implantation in a UHV system (≃ 10−8 Torr). For implantation in a DPV system, the Cr distribution broadens up to a factor of two. For Al a bimodal or broadened distribution could be observed by nuclear resonance profiling (NRP).