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Empirical Method for Quantitative Auger Analysis of Pseudo Binary Compounds and Mixed Two Phase Oxides, with Internal Concentration Gradients

IP.com Disclosure Number: IPCOM000081546D
Original Publication Date: 1974-Jun-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 3 page(s) / 51K

Publishing Venue

IBM

Related People

Chou, NJ: AUTHOR [+3]

Abstract

A method has been devised for empirically determining the chemical constituents of compounds and oxides used in thin film technologies.

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Empirical Method for Quantitative Auger Analysis of Pseudo Binary Compounds and Mixed Two Phase Oxides, with Internal Concentration Gradients

A method has been devised for empirically determining the chemical constituents of compounds and oxides used in thin film technologies.

This technique utilizes Auger electron spectroscopy (AES) in conjunction with sputter etching by argon ion bombardment, for analyzing the chemical constituents of these films.

Although the method is described in detail for a mixed oxide of PbO and In(2)O(3) (Pb(x)In(1-x)O), it is equally applicable to pseudo-binary compounds such as Ga(x)Al(1-x)As, noting the equivalency between lead, indium and oxygen to gallium, aluminum and arsenic, respectively.

An electron beam is focused normal to the surface of the oxide to be profiled. Ejected electrons are analyzed, the intensity of the signal associated with each element is taken to be proportional to the concentration in the sampled material. The compositional profile of the film is obtained by monitoring these signals during sputter etch removal of the oxide.

To translate the oxide compositional profile into volume fractions of PbO and In(2)O(3), an empirical relationship is utilized which relates the observed signal intensities of Pb and In to the volume fractions of the constituent phases, PbO and In(2)O(3), respectively. This empirical relationship is a linear dependence which exists between the Pb and In signals, i.e., A(In) = -mA(pb) + C where, A(In) and A(pb) refer to the signals associated with In and Pb, respectively, and m is the In-to-Pb Auger yield ratio. Plotting A(In) vs A(pb) (Fig. 1) shows this linear relationship which can be extrapolated to obtain intercepts A(pb) and A(In),
i.e., the signal intensities associated with a layer containing either 100% PbO or 100% In(2)O(3). Since the signal intensities of Pb and In are proportional to the volume fractions of PbO and In(2)O(3), respectively, knowledge of A(Pb) and A(In) allows Fig. 1 to be used as a calibration curve for the oxide, simply by relabelling the coordinates in terms of volume fractions (top and right scales, Fig.
1).

An additional empirical relationship which relates th Pb and in signals to the O signal in a linear combination, is used to verify th...