MEASUREMENT OF THE REFRACTIVE-INDEX OF THIN SIO2-FILMS USING TUNNELING CURRENT OSCILLATIONS AND ELLIPSOMETRY

We use Fowler-Nordheim tunneling current oscillations to accurately de termine the thicknesses of ultrathin SiO2 films, acid with the thickne sses as input, we employ precision single wavelength ellipsometry to d etermine the real part of the refractive index for thin SiO2 films in the range of 4-6 nm. An average value for this refractive index was fo und to be 1.894+/-0.110. This value is shown to yield SiO2 thicknesses to an accuracy of +/-0.1 nm. A SiO2 thickness-refractive index interp olation formula for the thin film regime is given. (C) 1996 American I nstitute of Physics.