Dynamic and high precision sensor positioning in large measuring ranges by means of an inverse measuring concept

• Applicants: Professor Dr.-Ing. Roland Füßl; Professor Dr.-Ing. Eberhard Manske
• Subject Area: Measurement Systems
• Term: from 2015 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 279458870

There are no limits to the technical challenges involved in measuring and positioning in large traverse ranges with nanometer to sub-nanometer precision. Semiconductor production is facing new challenges with wafers up to 700 mm in size and due to the constantly decreasing dimensions of the structures to be produced (currently in the sub-10 nm range). Already the 450 mm EUV technology requires ø 700 mm ultra-precise mirror optics with atomic precision. The inverse measuring concept with Abbe error compensation developed in the first project period represents a possible way out of the problem of the growing masses to be moved, while the requirements for positioning accuracy are constantly increasing. The measuring mirrors are one key component in any three-dimensional interferometric measuring or positioning task. The mirror surfaces represent the reference system of the entire structure and thus decisively determine the achievable measurement uncertainty. For this reason, the actual topography of the mirror surfaces must be exactly known in order to be able to correct their flatness deviations mathematically. Although precision optics production has developed enormously in recent years, both the achievable manufacturing tolerances and the measuring possibilities are still limited for the necessary large mirror surfaces. The desired increase in accuracy of the inverse concept therefore requires additional measuring technology in the actual measuring machine. For this purpose, the inverse measuring concept has to be extended for the ability for direct measurement of the mirror surfaces in the installed situation. This provides an option for regular or even permanent determination of the mirror topography and thus its arithmetical correction. In this way, the problem of a topography changing unknown in time, whether due to mechanical stresses, thermal strains or changes in the force flow within the machine, can be effectively countered. The flatness deviations of the mirror surfaces are to be recorded by additional measuring systems during the scan of the mirror surfaces and then be used directly for the correction of the length and angle measured values.

• DFG Programme: Research Grants