Measurement of the thickness of thin layers by the means of X-ray fluorescence with compensation for position of sample

摘要

A method of measuring the thickness of thin layers (9, 11) by X-ray fluorescence in which a specimen has X-rays (6) directed onto the area to be studied and emitted fluorescent radiation is detected by means of a detector (17). Errors in the layer measurements may be caused by differences in the separation between sample and detector for different samples. These errors may be compensated for by determining the relative separation of sample and detector and correcting the layer thickness measurements (21). Light from the sample is reflected off a mirror (14), passes through a focusing element (27) before being detected by a camera (28). An image of the sample, detected by the camera may be focused by moving the element, the position of which is measured (33) and is used to correct the layer thickness measurement. This obviates the need for having to move a workpiece carrying table in such a way that the work surface comes to rest at a predetermined measuring distance.