The surface chemical characterization of materials

Abstract

Summary form only given. The three most popular methods of surface analysis: Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS) will be described. These methods all have very good depth resolution in the range of 1-5 nm and particular attention will be paid to the resolution that is attainable in position (i.e. lateral resolution) and chemistry (e.g. the identification of different valence states). In the case of the electron spectroscopies (AES and XPS) it is possible to combine analysis with ion sputtering to provide a compositional depth profile, an analysis which can also be achieved, to better depth resolution, by monitoring the abundance of a specific ion as a function of depth. This data is readily converted to a compositional depth profile and forms the basis of a technique, frequently used for the assessment of dopant distribution in semiconductor devices, known as dynamic SIMS. For the analysis of sub-monolayer contamination low damage (static) SIMS is required. Angle resolved XPS is able to provide a composition depth profile in the 1-5 nm region and shows a great deal of promise for the analysis of shallow implants. For high resolution surface analysis scanning Auger microscopy is the method of choice with chemical images attainable at a resolution of around 15 nm. The application of these three techniques will be illustrated with a series of examples taken from recent work on microelectronics and other materials. The current state-of-the-art in instrument design will be described and future prospects considered. (1 page)