AVS 50th International Symposium
    QSA-10 Topical Conference Tuesday Sessions
       Session QS-TuP

Paper QS-TuP3
Measurement of Overlayer Properties Using Angle Resolved XPS

Tuesday, November 4, 2003, 5:30 pm, Room Hall A-C

Session: Aspects of Quantitative Surface Analysis
Presenter: R.G. White, Thermo Electron
Authors: P. Mack, Thermo Electron
B. McIntosh, Thermo Electron
R.G. White, Thermo Electron
J. Wolstenholme, Thermo Electron
Correspondent: Click to Email
Ultra-thin films (<10 nm) are encountered, for example, as gate oxides on transistors, self-assembled monolayers or surface contamination layers. Angle resolved XPS (ARXPS) can provide a convenient and non-destructive method for measuring thickness and distribution of the component materials within these layers. It will be shown that methods based on sputtering or single angle XPS measurements may produce misleading results. The equation commonly used for the calculation of overlayer thickness will be shown to have limitations that depend upon both the material and the overlayer thickness. Advanced methodologies for the determination of layer thickness from ARXPS data will be described and will be shown to overcome these problems. These methods include the simultaneous calculation of thickness of each layer in a multi-layer stack by fitting. The methods for measuring concentration depth profiles will be discussed. In some applications, it is essential to know the dose of an element within an ultra-thin layer, for example the distribution of nitrogen in a transistor gate oxynitride. It will be shown that large errors can be expected if such measurements are attempted using XPS without knowing the distribution of the nitrogen within the layer. Using ARXPS, the nitrogen distribution can be measured and a more accurate dose calculated from this distribution. Application of ARXPS to thin films will be shown to be a powerful technique for the measurement of dose distribution and thickness but care must be taken to ensure that all of the required parameters are taken into account.