Lensless EUV mask inspection for anamorphic patterns

Abstract

Anamorphic mask design is necessary to overcome the geometrical limitation imposed by the reflective geometry used in EUV lithography projection systems and will be used in high-NA EUVL scanners. In this study, we demonstrate the capability of anamorphic imaging using CDI. We created anamorphic EUV masks with programmed defects and inspected it with RESCAN, a lensless microscope dedicated to EUV mask inspection.

Towards fast ptychography image reconstruction of EUV masks by deep neural networks

“…Actinic mask inspection systems, on the other hand, mimic the operational conditions of the scanner by imaging at a wavelength of 13.5 nm. [3][4][5][6] Ptychography, a computational imaging method that images a sample by processing a series of diffraction patterns obtained by illuminating the object at overlapping probe positions, is a promising alternative to conventional actinic mask inspection methods, owing to its robustness, flexibility and relatively simple and lens-free optical design. 7,8 On the other hand, the need for a scanning illumination, the requirement for a large overlap among adjacent probe positions, the need to handle a significant volume of data, and the slow iterative phase retrieval process pose throughput challenges that need to be properly evaluated and addressed.…”