LTHOUGH numerous attempts have been made to model the A thermal oxidation process of silicon, some obscurities seem to remain in this matter. So, in Ref. 1, Eqs. (10) and (1 l), the migration of network oxygen in the oxide layer is considered in a way that the corresponding concentration c, of the species is believed to obey Fick's Law where D,(x) is the position-dependent diffusion coefficient of the network oxygen.The physical reason is explained by the assumption that the dopant migration would occur via point defects. To quote, "Network diffusion is thought of as a process equivalent to lattice diffusion in crysalline oxides; i.e., defects in the network structure equivalent to vacancies allow oxygen ions to jump directly from one network site to another."' However, the physical principle seems to be incorrectly formulated in Eq. (1). In accordance with an older model of the dopant migration via inhomogeneously distributed vacancies in a simple cubic crystal, the resulting dopant flux density J (all vectors are written here as scalars, because they are one-dimensionally considered) is given by the relationshipz4 where a = lattice spacing = dopant jumping distance; p = vacancy concentration; o = dopant jumping rate; C = dopant concentration; E = electric field; K = dopant-vacancy-neighborhood constant; T = absolute temperature; k = Boltzmann constant; q = dopant ion charge; and p' = @/ax, w' = awlax, ct = aciax.