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Proceedings Paper

Debris- and radiation-induced damage effects on EUV nanolithography source collector mirror optics performance
Author(s): J. P. Allain; M. Nieto; M. Hendricks; S. S. Harilal; A. Hassanein
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Paper Abstract

Exposure of collector mirrors facing the hot, dense pinch plasma in plasma-based EUV light sources to debris (fast ions, neutrals, off-band radiation, droplets) remains one of the highest critical issues of source component lifetime and commercial feasibility of nanolithography at 13.5-nm. Typical radiators used at 13.5-nm include Xe and Sn. Fast particles emerging from the pinch region of the lamp are known to induce serious damage to nearby collector mirrors. Candidate collector configurations include either multi-layer mirrors (MLM) or single-layer mirrors (SLM) used at grazing incidence. Studies at Argonne have focused on understanding the underlying mechanisms that hinder collector mirror performance at 13.5-nm under fast Sn or Xe exposure. This is possible by a new state-of-the-art in-situ EUV reflectometry system that measures real time relative EUV reflectivity (15-degree incidence and 13.5-nm) variation during fast particle exposure. Intense EUV light and off-band radiation is also known to contribute to mirror damage. For example offband radiation can couple to the mirror and induce heating affecting the mirror's surface properties. In addition, intense EUV light can partially photo-ionize background gas (e.g., Ar or He) used for mitigation in the source device. This can lead to local weakly ionized plasma creating a sheath and accelerating charged gas particles to the mirror surface and inducing sputtering. In this paper we study several aspects of debris and radiation-induced damage to candidate EUVL source collector optics materials. The first study concerns the use of IMD simulations to study the effect of surface roughness on EUV reflectivity. The second studies the effect of fast particles on MLM reflectivity at 13.5-nm. And lastly the third studies the effect of multiple energetic sources with thermal Sn on 13.5-nm reflectivity. These studies focus on conditions that simulate the EUVL source environment in a controlled way.

Paper Details

Date Published: 18 May 2007
PDF: 9 pages
Proc. SPIE 6586, Damage to VUV, EUV, and X-ray Optics, 65860W (18 May 2007); doi: 10.1117/12.723692
Show Author Affiliations
J. P. Allain, Argonne National Lab. (United States)
M. Nieto, Argonne National Lab. (United States)
M. Hendricks, Argonne National Lab. (United States)
S. S. Harilal, Argonne National Lab. (United States)
A. Hassanein, Argonne National Lab. (United States)

Published in SPIE Proceedings Vol. 6586:
Damage to VUV, EUV, and X-ray Optics
Libor Juha; Ryszard H. Sobierajski; Hubertus Wabnitz, Editor(s)

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