Measurements and Modeling of Thin Silicon Dioxide Films on Silicon

Abstract

The ellipsometric measurement of refractive indexes for films less than 50 nm thick is of dubious quality due to the significance of the size of random errors relative to the accuracy required to extract reliable index values from the measurements. In this study the various errors are quantitatively assessed as a function of the film thickness, and then compared with experimental data obtained from differently prepared silicon dioxide films on silicon. The new results confirm previous work that shows higher refractive indexes for thinner films. Transmission electron microscopy confirms the results. Graded and discrete layer models are compared.