The precipitation of oxygen in silicon has been studied in the temperature range 650 to 1050 degrees C using the techniques of chemical etching, IR absorption applied to the 9 mu m band (4.2K), and small-angle neutron scattering (SANS). The IR data and etch pit counts, relating to the number densities of precipitate particles, have been fitted to Ham's theoretical model for the diffusion limited growth of randomly distributed particles. Full allowance is made for the increase in size of the precipitates with increasing time and good agreement is found over the complete period starting from zero time. Values of the diffusion coefficient of oxygen so determined are in excellent agreement with other data obtained by different methods, including SANS measurements at 750 degrees C described in the present work. The combined data give D=0.11 exp(-2.51 eV/kT) cm2s-1. The SANS data also indicate that the precipitates are not spherical in shape after a short initial period, and they show that the initial concentration of particles nucleated decreases with annealing time. The solid solubility cs(T) is determined at each temperature and compared with previous measurements. The authors conclude that the best combination of results leads to cs(T)=2.6*1022 exp(-1.4 eV/kT) down to 850 degrees C. At lower temperatures cs decreases more slowly with decreasing temperature, indicating a possible change in the structure or the form of the precipitated SiO2 phase.

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The kinetics of oxygen precipitation in silicon have been determined from measurements of the IR 9-μm absorption band (4.2 K) and we obtain the time constant τ0 for the exponential approach to equilibrium for several temperatures. The density N of precipitate particles was measured directly by chemical etching, and inferred from IR scattering and cold neutron scattering. We use our values of τ0 and N to calculate the diffusion coefficient of oxygen in bulk silicon. This is the first time that this procedure has been used, and we obtain D=0.02 exp(−2.42 eV/kT) cm2 s−1 in the temperature range 650–1050 °C.