Kinetics of growth of the oxidation stacking faults

Abstract

A model for the growth of oxidation stacking faults (OSF) has been developed with three main hypotheses: (1) The growth of the OSF is due to the diffusion of silicon self-interstitials from the Si-SiO2 interface to the partial dislocation. The diffusion coefficient of the interstitials can be determined from the data of silicon self-diffusion. (2) The concentration of interstitials at the Si-SiO2 interface, Cs, is determined by the equilibrium between the interstitials and the atoms of oxygen free to react with the silicon atoms, Cs =4.1×1018t−0.25 PO20.25 exp(−0.5/kT) F, where Cs is in cm−3, t is the time in seconds, PO2 is the oxygen partial pressure in atmospheres, and kT is in eV. F value is 1 for wafers of (001) orientation, and 0.7 for the (111) wafers. (3) The concentration of the interstitials in equilibrium with the partial dislocation, C0, in cm−3, is C0=12×1025 exp(−3.02/kT), with kT in eV. The majority of the experimental data can be calculated from R =1640Ft0.75 PO20.25 exp(−2.5/kT) −3.6×1010t exp(−5.02/kT), where R is one-half of the OSF length in cm, t is in sec, PO2 is in atmospheres, and kT is in eV. The role of the vacancies in the OSF growth is also discussed, but the model favors a mechanism of silicon self-diffusion involving a silicon interstitial, and a double mechanism for boron diffusion.