Oxygen diffusion in silicon was known to be affected by high concentrations of impurities, although the mechanism underpinning this was poorly understood. oxygen transport in Czochralski silicon was studied by analyzing data on the locking of dislocations by oxygen as a function of time and temperature. New data from crystals grown so as to contain high levels of germanium and arsenic were presented here. These new data were analyzed, together with previous data for silicon having a high boron concentration, in order to understand further the mechanism by which high impurity concentrations affected oxygen transport at temperatures at which the oxygen dimer dominated transport (up to 550C). The results showed that a high level of boron doping (∼3 x 1018/cm3) enhanced the effective diffusivity of oxygen by a factor of ∼8 to ∼25 relative to low doped material with the same oxygen concentration. High levels of germanium doping (∼8  x  1019/cm3) and arsenic doping (∼2  x  1019/cm3) could both have a slight retardation effect on oxygen transport. The magnitude of the reduction measured was less than a factor of ∼4 in the heavily germanium doped specimens and less than a factor of ∼5 in the heavily arsenic doped specimens, and in most cases was significantly less than this. Germanium doping introduces considerable strain into the silicon lattice without affecting the Fermi level position, so data from these samples showed that lattice strain affects oxygen dimer transport. The arsenic and boron doping levels in the materials studied gave rise to lattice strain with a smaller magnitude and opposite sign to that in the germanium doped samples. It was therefore suggested that the Fermi level position also affects the transport of oxygen dimers.

The Effect of Impurity-Induced Lattice Strain and Fermi Level Position on Low Temperature Oxygen Diffusion in Silicon. Z.Zeng, J.D.Murphy, R.J.Falster, X.Ma, D.Yang, P.R.Wilshaw: Journal of Applied Physics, 2011, 109[6], 063532