The effect of debris on collector optics, its mitigation and repair: Next-step a gaseous Sn EUV DPP source

Brian E. Jurczyk, Darren A. Alman, Erik L. Antonsen, Michael A. Jaworski, Michael J. Williams, David N. Ruzic, Timothy Spila, Ginger Edwards, Stefan Wurm, Obert Wood, Robert L. Bristol

Research output: Contribution to journalConference articlepeer-review

Abstract

The critical issue related to advanced fuel plasma EUV sources is collector lifetime. The Illinois Debris-mitigation EUV Applications Laboratory (IDEAL) is continuing research with a dense plasma focus (DPF) light source. The IDEAL DPF electrodes have been redesigned in order to allow for advanced fuel testing, better pinch operation and increased debris generation. The DPF light source operates at negative polarity, 50 Hz, 3 kV and 7.5 Joules of energy per pulse with tetramethyltin [(CH3)4Sn] as an advanced fuel source. EUV output power is measured with filtered photodiodes and results from a gridded energy analyzer still show two primary ion components with a high-energy peak near 6keV. A Faraday-shielded immersed RF antenna provides a 2kW secondary discharge near the DPF for both pre-ionization and mitigation of the debris with a foil trap (>90%). In addition the Surface Cleaning of Optics by Plasma Exposure (SCOPE) facility has been constructed where evaporated and/or ion implanted metals can be deposited on and removed from EUV mirrors. In SCOPE metals were evaporated on to mirror samples held at various temperatures. A metal ion beam was also added to simulate the energetic erosive flux and a helicon plasma was used in situ to study plasma cleaning. Reactive ion etching of tin by chlorine and other gases has shown 500:1 selectivity factors and very high etch rates suitable to refresh an optical mirror surface within a few seconds. Mirror samples were analyzed at the Center for Microanalysis of Material where the diffusion and transport of the metals and surface roughness were studied for lifetime estimation. Lastly, the Xtreme Characterization EUV Experiment Device (XCEED) was used for characterization of the debris has been accomplished by use of an energy sector analyzer in combination with ion time-of-flight. This diagnostic has been designed to measure velocity, mass and charge states of the incoming ions and neutrals, giving discrete debris spectra while in negative polarity operation. Latest results will be presented based on this work.

Original languageEnglish (US)
Article number65
Pages (from-to)572-577
Number of pages6
JournalProgress in Biomedical Optics and Imaging - Proceedings of SPIE
Volume5751
Issue numberI
DOIs
StatePublished - 2005
EventEmerging Lithographic Technologies IX - San Jose, CA, United States
Duration: Mar 1 2005Mar 3 2005

Keywords

  • Collector lifetime
  • Debris
  • Debris spectra
  • EUV source
  • Etching
  • Mitigation
  • Optics
  • Plasma cleaning

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Radiology Nuclear Medicine and imaging

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