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

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

doi:10.1117/1.JMM.16.4.041003

27 July 2017 RESCAN: an actinic lensless microscope for defect inspection of EUV reticles

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

Journal of Micro/Nanolithography, MEMS, and MOEMS, Vol. 16, Issue 4, 041003 (July 2017). https://doi.org/10.1117/1.JMM.16.4.041003

Abstract

Actinic mask defect inspection is an essential process step for the implementation of extreme ultraviolet (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 goal of the RESCAN project is to develop a tool capable of inspecting an EUV reticle in 7 h and detect mask defects down to a size of 10 nm×10 nm. The lensless imaging concept allows overcoming the resolution limitations due to the numerical aperture and lens aberrations of conventional 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 reticle image providing us also with extremely valuable information about phase and mask three-dimensional 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.

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Iacopo Mochi, Patrick Helfenstein, Istvan Mohacsi, Rajeev Rajendran, Dimitrios Kazazis, Shusuke Yoshitake, and Yasin Ekinci "RESCAN: an actinic lensless microscope for defect inspection of EUV reticles," Journal of Micro/Nanolithography, MEMS, and MOEMS 16(4), 041003 (27 July 2017). https://doi.org/10.1117/1.JMM.16.4.041003

Received: 8 May 2017; Accepted: 10 July 2017; Published: 27 July 2017

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