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Proceedings Paper

Tin droplets for LPP EUV sources
Author(s): Bob Rollinger; Luna Bozinova; Nadia Gambino; Reza S. Abhari
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Paper Abstract

The tin droplet generator is a key component of EUV LPP sources. Small tin droplets, when combined with a high power laser, form a regenerative target with high CE. A major challenge associated with today's EUV sources is energy stability, which directly correlates with the stability of the fuel delivery system. The LEC droplet dispenser is now in its 5th generation design, with several years of development, including studies of different nozzle types, excitation mechanisms, thermal management approaches and contamination control systems. The dispenser produces droplets in the frequency range required for both metrology and HVM EUV sources. The two relevant instability modes are drop-to-drop jitter and lateral instabilities. The low frequency content of the lateral droplet displacement is compensated by a newly implemented dispenser positioning system. The drop-to-drop jitter, which is studied over 2000 s, equals 11.2% (3σ) of the mean droplet spacing, which makes individual droplet laser triggering necessary. The lateral instabilities, which are mainly relevant in the plane perpendicular to the laser axis, are determined to be in the range of 7.1% (3σ;) of the droplet diameter. The lateral displacements are recorded over 2.2 hrs. The related EUV temporal energy stability (open-loop) is estimated to be 0.35% (3σ) for the worst case scenario, a laser spot size which matches the droplet diameter.

Paper Details

Date Published: 23 March 2012
PDF: 9 pages
Proc. SPIE 8322, Extreme Ultraviolet (EUV) Lithography III, 83222P (23 March 2012); doi: 10.1117/12.916683
Show Author Affiliations
Bob Rollinger, ETH Zurich (Switzerland)
Luna Bozinova, ETH Zurich (Switzerland)
Nadia Gambino, ETH Zurich (Switzerland)
Reza S. Abhari, ETH Zurich (Switzerland)

Published in SPIE Proceedings Vol. 8322:
Extreme Ultraviolet (EUV) Lithography III
Patrick P. Naulleau; Obert R. Wood II, Editor(s)

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