Ion Implantation Damage Gettering and Phosphorus Diffusion Gettering of Cu and Au in Silicon
The profiles and lattice location of Cu and Au have been determined for ion implantation damage and phosphorus diffusion gettering using Rutherford backscattering from the gettered surfaces. Junction leakage studies on the opposite surface -were used to correlate the results of the gettering. Prior to the gettering, the samples were intentionally equilibrated with moderate levels of Cu and Au. Random and channeled spectra on phosphorus diffused surfaces show that the Au and Cu are mainly on substitutional sites: ~ 90% for Au and ~75% for Cu. Substitutional Au and Cu are (ionized) acceptors, whose solubility is greatly enhanced by the high concentration of (ionized) phosphorus donors. Backscattering from surfaces with the Si-O-P glass on the silicon unambiguously show that the Cu and Au are gettered almost entirely in the silicon rather than into the glass phase. Densities as high as 1020 Cu/cm3 and 1019 Au/cm3 are found gettered in the phosphorus diffused surface of the contaminated silicon. Backscattering from the implanted-damaged-annealed surfaces, show that the Cu and Au are trapped in the damaged region but are not on lattice sites. For the experimental conditions used, the phosphorus diffusion was a more effective getterer than the implantation-damage; in particular, Au was ~ one-third as effectively gettered by the implantation damage for the same annealing time, temperature (1000°C), and oxygen ambient. Junction leakage measurements on Au contaminated samples confirm that Au was less effectively gettered by the implantation damage. Junction leakage measurements on Cu contaminated and gettered samples also show this trend. Possible models such as ion pairing for the diffusion gettering, and adsorption of atoms on dislocations for the damage gettering are discussed.
KeywordsChannel Number Lattice Location Substitutional Site Phosphorus Diffusion Implantation Damage
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