Comparison of nanometer-thick films by x-ray reflectivity and spectroscopic ellipsometry
Date
2005
Authors
Menoni, Carmen, author
Dummer, Ann M., author
Dorhout, Peter K., author
Rithner, Christopher D., author
Kohli, Sandeep, author
American Institute of Physics, publisher
Journal Title
Journal ISSN
Volume Title
Abstract
Films of tantalum pentoxide (Ta2O5) with thickness of 10-100 nm were deposited on Si wafers and have been compared using spectroscopic ellipsometry (SE) and x-ray reflectivity (XRR). (Ta2O5) was chosen for comparison work based on various criterions for material selection outlined in this article. Measurements were performed at six positions across the sample area to take into consideration thickness and composition inhomogeneity. SE and XRR fitted curves required the incorporation of a linearly graded interface layer. SE systematically measured higher values of film thickness as compared to XRR. A linear equation was established between the thickness measurements using SE and XRR. The slope of the linear equation established was found to be 1.02±0.01. However, the intercepts were found to be 1.7±0.2 and 2.6±0.3 when the interface was excluded and included, respectively. These differences in the values of intercepts were attributed to the uncertainties in the determination of the interface layer.