Diffusion limited precipitation of oxygen in dislocation-free silicon

Abstract

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.

Morphology and oxidation kinetics of SiO2layers on silicon

“…The decrease of density at 1050 • C has to be attributed to a change of the Si lattice (softening). Similar phenomena have been observed in oxygen precipitation in Si [28]. The above model is further corroborated from the wider spread of densities at the temperatures for which the mean density is high (900-1000 • C) and the presence of the surface profile B (appearing only in some samples at 1000 and 1050 • C).…”

“…The SiO 2 exhibits polymorphism even at atmospheric pressure and the pressure-temperature phase diagram is quite complex (for example, coesite and stishovite with densities 3 and 4.4 g cm −3 , respectively [27]). During oxide growth, especially at the initial stages studied here, most probably high pressures are created in the Si lattice as oxygen atoms are incorporated and Si interstitials emitted, if we assume a mechanism similar to that which takes place in the formation of SiO 2 precipitates in crystalline Si [28,29]. These high pressures would result in the formation of high pressure SiO 2 phases or mixture of low and high pressure phases.…”