Surface roughness scattering at the Si–SiO2 interface

Abstract

Scattering of inversion layer electrons at the oxide semiconductor interface is a major source of mobility degradation in MOSFETs. We have studied, on the same sample, high resolution TEM cross sections of the Si–SiO2 interface and detailed temperature dependent electronic and magnetic transport measurements. The expeirmental mobility data are compared to a model containing terms for surface roughness and impurity scattering including carrier screening. The statistical properties of the interface fluctuations appear as parameters which are adjusted to fit the transport data. While the TEM pictures indicated an interfacial boundary which deviated by only one atomic layer, an assumed peak-to-peak deviation of approximately five atomic layers is required to fit the experimental mobility. Thus, while the overall comparison of the surface parameters suggests that roughness scattering is a plausible mechanism, close agreement between the theory and experiment is not obtained.