Free-standing subwavelength grid infrared cut filter of 90 mm diameter for LPP EUV light source

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6 Citations (Scopus)


Abstract A subwavelength grid infrared (IR) cut filter as large as 90 mm in diameter was fabricated and tested on a 6 inch Si wafer for a laser-produced plasma (LPP) extreme ultraviolet (EUV) light source used in the next generation lithography tools. The IR cut filter is a grid type, which has higher thermal stability compared with a conventional multilayer metal membrane filter. The grid is a free-standing Molybdenum coated Si honeycomb structure with a thickness of 5 μm, a wire width of only 0.35 μm and a pitch of 4.5 μm. Such a large-size free-standing microstructure was successfully fabricated by carefully balancing film stress at each process step. The fabricated IR cut filter demonstrated 99.7% rejection for 10.6 μm IR light. The IR cut filter was finally installed in a LPP EUV light source.

Original languageEnglish
Article number8852
Pages (from-to)59-64
Number of pages6
JournalSensors and Actuators, A: Physical
Publication statusPublished - 2015 Aug 11
Externally publishedYes


  • Balancing film stress
  • EUV lithography
  • IR filter
  • LPP EUV lighting source
  • Subwavelength grid

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Instrumentation
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Electrical and Electronic Engineering


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