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Electron Beam Microanalysis

IP.com Disclosure Number: IPCOM000081331D
Original Publication Date: 1974-May-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Landenberger, R: AUTHOR [+3]

Abstract

During electron-beam microanalysis, the material of a sample, by being subjected to a focused electron beam, is caused to emit a characteristic X-radiation. This radiation originates from a pear-shaped volume whose depth is a function of the energy of the primary electrons,and whose lateral expansion is governed by the atomic number of the sample material.

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Electron Beam Microanalysis

During electron-beam microanalysis, the material of a sample, by being subjected to a focused electron beam, is caused to emit a characteristic X- radiation. This radiation originates from a pear-shaped volume whose depth is a function of the energy of the primary electrons,and whose lateral expansion is governed by the atomic number of the sample material.

The figure shows schematically, the intensity distribution I(t) within the excited volume at a predetermined primary electron energy value. The intensity which is low at the surface of the sample (t=0) declines after having reached a maximum value at a certain depth.

When a thin layer on top of a substrate material is analysed, the intensity of the resulting X-radiation is proportional to the area F below the I(t) curve in the proximity of t=0. This intensity is low, as area F is small for low t values. But the intensity can be increased by shifting the integration boundaries (a, b) along the t-axis towards higher I(t) values (see figure).

This is effected by vapor depositing a layer of suitable material on the layer to be analyzed. The vapor deposited electron stopping layer should consist of a material that leads only to a slight absorption of the X-radiation of the layer to be analyzed. As the interaction between electrons and matter is stronger than that between X-radiation and matter, the electron stopping layer can be very thin, so that the X-ray absorption is neglectable in m...