Analysis of AuPd thin coatings on lead frames

New technologies in microelectronics require the non-destructive analysis of very thin coatings down to the nm-range. X-Ray fluorescent spectroscopy is used already for a long time for coating thickness testing. But typical thickness was in the $\mu$m-Range. By using detectors with high-energy resolution and X-Ray optics to concentrate a high intensity to the sample it is possible to enhance the sensitivity of XRF also for very thin coatings. In the paper a $\mu$-XRF spectrometer is described that can be used for the analysis of thin coatings. Test measurements are presented for typical samples that demonstrate a high repeatability and stability for this instrument. The accuracy is determined by the quality of the calibration model or by the available references. Finally the methodology of the user interface is described. Key words. micro-Xray-fluorescence, coating thickness testing, sub-nm-range thickness