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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 (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 (DSIMS). 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. 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

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Page 1: [IEE IEE Colloquium on Materials Characterisation - How Can We Do It? How Can It Tell Us? - London, UK (4 Dec. 1997)] IEE Colloquium on Materials Characterisation - How Can We Do It?

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