TEM investigation of thin oxides in MOS structures

High resolution lattice imaging of cross-sectional specimens of thin MOS structures was used to determine the thickness of the gate oxide, this geometrical thickness is compared with thickness values obtained from C-V measurements, measurements of the Shubnikov-de Haas oscillations at 4.2 K, Fowler-Nordheim tunneling and ellipsometry. To get most probable thickness values for the SiO₂ layer, for the transition region SiO₂ and for the average distance of the electrons from the Si/SiO₂ interface, all five methods have been applied on the same sample.