SiSiO2 interfacial atomic scale roughness caused by inhomogeneous thermal oxidation

Abstract

A new model to describe the thickness inhomogeneities and the roughness of the interfaces of thin SiO2 films is presented. This model is compatible with the actual kinetics of silicon oxidation and can be used to study the influence of the oxidation conditions on the final homogeneity of the film at the atomic scale. Monte Carlo methods are used to simulate the inhomogeneous SiO2 growth and an analytical expression for the distribution of thickness inhomogeneities is also derived. The Monte Carlo simulations are used to simultaneously determine the distribution of local thicknesses as a function of the oxidation time and the average growth law of the rough film. As in previous works, the experimentally observed non‐stoichiometric SiOx layer is reinterpreted in terms of the microroughness. The thickness of this apparent non‐stoichiometric layer, which depends on the oxidation conditions, is obtained as a function of the total oxide thickness. The presented model is appropriate to investigate the influence of the SiO2 thickness inhomogeneities on the electrical performance of MOS structures and, since it is compatible with the actual oxide growth mechanisms, it can be used to determine which oxidation conditions are suitable to minimize the effects of these inhomogeneities.

Characterization of the Si/SiO2 interface morphology from quantum oscillations in Fowler–Nordheim tunneling currents

“…The oxidation model presented above is consistent with this type of behavior. Other authors have theorized that the oxidation process will roughen a flat surface, and that the roughness can be described by a Poisson distribution of local oxide thicknesses 12 ' 13 . There is probably a combination of effects occurring and the surface morphology will evolve in a way that depends on the specific processing conditions to which it is exposed.…”