RESCAN:  an actinic lensless microscope for defect inspection of EUV reticles

Iacopo Mochi; Patrick Helfenstein; Istvan Mohacsi; Rajeev Rajendran; Shusuke Yoshitake; Yasin Ekinci

doi:10.1117/12.2258086

24 March 2017 RESCAN: an actinic lensless microscope for defect inspection of EUV reticles

Iacopo Mochi, Patrick Helfenstein, Istvan Mohacsi, Rajeev Rajendran, Shusuke Yoshitake, Yasin Ekinci

Proceedings Volume 10143, Extreme Ultraviolet (EUV) Lithography VIII; 101431O (2017) https://doi.org/10.1117/12.2258086
Event: SPIE Advanced Lithography, 2017, San Jose, California, United States

Abstract

Actinic mask defect inspection is an essential process step for the implementation of EUV Lithography in high-volume manufacturing. The main challenges for any mask defect inspection platform are resolution, sensitivity, and throughput. The reflective-mode EUV mask scanning lensless imaging microscope (RESCAN) is being developed to provide actinic patterned mask inspection capabilities for defects and patterns with high resolution and high throughput, for node 7 and beyond. Namely, the first goal of the RESCAN project is to develop a tool capable of inspecting an EUV reticle in about 7 hours and detect mask defects down to a size of 10 nm. The lensless imaging concept allows to overcome the resolution limitations due to the numerical aperture (NA) and lens aberrations of conventional actinic mask imaging systems. With the increasing availability of computational power and the refinement of iterative phase reconstruction algorithms, lensless imaging became a powerful tool to synthesize the complex amplitude of the actinic aerial image providing us also with extremely valuable information about phase and mask 3D effects. Here, we present a brief description of the current prototype of the RESCAN platform and illustrate a few experimental examples of programmed defect detection.

Citation Download Citation

Iacopo Mochi, Patrick Helfenstein, Istvan Mohacsi, Rajeev Rajendran, Shusuke Yoshitake, and Yasin Ekinci "RESCAN: an actinic lensless microscope for defect inspection of EUV reticles", Proc. SPIE 10143, Extreme Ultraviolet (EUV) Lithography VIII, 101431O (24 March 2017); https://doi.org/10.1117/12.2258086

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