The locking of dislocations by O atoms, in Czochralski Si at 350 to 700C, was studied. Investigations were carried out for various O concentrations, annealing times (10 to 3 x 107s), and point-defect concentrations. It was found that the unlocking stress of dislocations at low temperatures obeyed a similar trend to those previously observed at higher temperatures, and was affected by the annealing temperature, time and O concentration. Within the present temperature range, the results indicated an enhanced transport of O to dislocations. Numerical solution of the diffusion equation for O transport to dislocations showed that the effective diffusivity of O at lower temperatures diverged from the so-called normal diffusivity of O. It was shown that the O transport could be as much as 3 orders of magnitude higher than that expected from extrapolating data which were obtained at higher temperatures. In the low-temperature regime, the effective diffusivity depended upon the O concentration and the activation energy was about 1.5eV.

Oxygen-Dislocation Interactions in Silicon at Temperatures below 700C: Dislocation Locking and Oxygen Diffusion. S.Senkader, P.R.Wilshaw, R.J.Falster: Journal of Applied Physics, 2001, 89[9], 4803-8

Table 78

Diffusivity of O in Si