[iee iee colloquium on materials characterisation - how can we do it? how can it tell us? - london,...
TRANSCRIPT
The Surface Chemical Characterization of Materials
John F Watts
School of Mechanical and Materials Engineering UNIVERSITY OF SURREY
Guildford Surrey GU2 5XH UK
The three most popular methods of surface analysis: Auger electron spectroscopy
(AES), X-ray photoelectron spectroscopy ( X P S ) 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 X P S ) 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 (DSIMS). For the analysis of sub-monolayer contamination
low damage (static) SIMS is required. Angle resolved X P S 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.
JFW
1.9.97
3 1997 The Institution of Electrical Engineers. 'rinted and published by the IEE, Savoy Place, London WCPR OBL, UK 21 1