Multi Layer Analysis: Determination of the Thickness and the Chemical Composition of the Individual Layers of Multilayer Systems in SEM

Measurement of the thickness of thin films both unsupported and on substrates can be performed with a high accuracy down to a thickness of 2 nm as well by EPMA as by SEM-EDX. For this purpose the ratio between the X-ray intensity of the film and the intensity of the same element of a bulk standard is used. In the X-ray analysis of bulk specimens, it is usual to use standars as similar to the unknown specimen as possible. Thus a compensation for eventual shortcomings of the underlying theoretical models is possible. This is generally impossible in the case of thin films. This lack of compensation between standards and unknown specimen provides a lot of information on the accuracy and the importance of some of the basic expressions and parameters of the theoretical models and also the maximum error cause by them.