Thin film thickness measurement using electron probe microanalyzer

Abstract

A non-destructive method for measuring the thickness of thin films deposited on a substrate has been developed with a conventional scanning electron microscope (SEM) equipped with ultra-thin window energy dispersive X-ray spectrometer (EDS). It is based physically on that the penetrant depth of electrons decreased as the accelerate voltage of incident electron lowered. By measuring the intensity ratio of an X-ray peak of the thin film to one of substrate at different accelerate voltage; the relation of intensity ratio of Is/If with electron energy is obtained. And when the penetrant depth of electrons is equal to the films thickness, change of the ratios both films and bulk standard is identical, theoretically. Then the thickness of thin films can be calculated by combining the expression of the experimental data and Sewell's formula. The thicknesses of FeCoSiB compound films on glass substrate were determined by this method. Comparing the results with the data taken from the stylus profilometry measurement, it shows that the method of measuring the thickness of thin films by EDS is reasonable and practicable.