An investigation was made of the suggestion that P diffusion at concentrations above the solid solubility generated Si self-interstitials. Buried layers of Sb were created by implanting 150keV Sb into [100]-type substrates, to 5 x 1013/cm2. After annealing (900C, 0.5h) in N, an 0.008 to 0.01mm thick epilayer was grown over the buried layers. Masking oxides were then created by liquid-phase chemical vapor deposition of 0.001mm SiO2 layers, or by thermal oxidation at 900C in steam. Spreading resistance profiles were recorded and secondary ion mass spectrometry was used to characterize the chemical P doping densities. Plan-view and cross-sectional transmission electron microscopy was used to look for SiP precipitates and defects in the P-diffused layers. It was found that P-related precipitates, 0.0001 to 0.0002mm in size, were observed in some samples by using transmission electron microscopy. In every case, their concentration was insufficient to account for the concentration of non-electrically active P. Measurably retarded diffusion of Sb in the buried layers occurred at temperatures ranging from 1100 to 1200C, with an activation energy of about 6.6eV. Stacking fault growth in buried Sb layers under the P-diffused region implied that Si self-interstitial supersaturation was produced in the P-doped layer. Self-interstitials fed stacking fault growth and retarded Sb diffusion. The number of self-interstitials generated could not be accounted for by the sparse number of precipitates which formed in the P-diffused region.

J.C.C.Tsai, D.G.Schimmel, R.B.Fair, W.Maszara: Journal of the Electrochemical Society, 1987, 134[6], 1508-18