Commissioning an EUV mask microscope for lithography generations reaching 8 nm

Abstract

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Optical Microscopy Has Evolved To Overcome Limitations in Resolution and Image Clarity, (An Overview of Some Available Options)

“…EUV microscopes are highly technique sensitive and the smallest misalignments of any optical component can result in enormous final image aberrations. Thus wavelength control and nano-focusing are important challenges in addition to thermal drift, vibration and other anomalies [14]. This highlights the importance of great precision in manufacturing and assembling each of the component parts of the microscope together with skilled manipulation of the instrument.…”

Phase measurements of EUV mask defects

“…4 The algorithm is able to consider partially coherent illumination allowing it to more closely match the illumination used during wafer printing while also providing potentially higher throughput. 5 We show that the algorithm accurately recovers the defect by measuring the same native defect with two different zone plate lenses-a phase contrast lens and a standard zone plate.…”

Aberration estimation using EUV mask roughness

“…5 We applied the algorithm to measurements of EUV multilayer roughness conducted using the SHARP microscope at Lawrence Berkeley National Laboratory. 6 Due to field varying aberrations and image movement caused by non-telecentricity, the algorithm was modified to calculate the aberrations for each aerial image using ray tracing. Instead of optimizing over individual aberrations, the modified algorithm optimized over the position and orientation of the zone plate to reduce the number of parameters and to handle how aberrations change with focus.…”