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Marker structures with accurate positions

PTB News 2.2021
26.03.2021
Especially interesting for

dimensional metrology

precision engineering

In der industriellen Fertigung werden häufig Markerstrukturen genutzt, um die relative Lage zweier Objekte zueinander zu ermitteln. Eine neue Messmethode der PTB hat durch die Kombination von optischem Imaging und Scatterometrie eine Auflösung der räumlichen Überlagerung von unter 1 nm erreicht und ist dabei besonders schnell. 

Schematic representation of the signals by means of erroneous (a) and correct (b) overlapping

Marker structures are often used in industrial manufacturing to determine the relative position of two objects in relation to each other. By combining optical imaging and scatterometry, a new measurement method devised by PTB has reached a resolution of less than 1 nm for spatial overlapping and is particularly fast at doing so. For this purpose, marker structures are put into the focus of a laser, and the light these structures scatter is detected on a quadrant photodiode. If the structures overlap exactly, a symmetrical intensity distribution is yielded at the diode. Deviations from this are an exact measure of the quality of the overlapping. This method can be integrated into a measurement process by means of simple optical components. (Technology Offer 522)

Advantages

resolution of a spatial overlapping < 1 nm

fast detection

easy integration