Paper
18 March 2009 Grid spectral purity filters for suppression of infrared radiation in laser-produced plasma EUV sources
Wouter A. Soer, Martin J. J. Jak, Andrei M. Yakunin, Maarten M. J. W. van Herpen, Vadim Y. Banine
Author Affiliations +
Abstract
We have developed a grid-type spectral purity filter (SPF) for suppression of infrared radiation in laser-produced plasma (LPP) EUV sources for high-volume EUV lithography. The SPF is a silicon grid with sub-wavelength periodicity that is metalized to make it reflective for infrared radiation. EUV radiation is transmitted geometrically through the open area of the grid. The first prototype samples show an in-band EUV transmittance of 74% at normal incidence. Infrared spectrometry exhibits a clear cut-off behavior as expected, with a transmittance of <0.1% at a wavelength of 10.6 µm. In a first power-load test, a grid was exposed to a CO2 laser at 100 W/cm2 in vacuum for 8 hours. Another grid was kept at 800 °C in a vacuum oven for 24 hours. Both grids remained structurally intact and maintained an infrared transmittance of <0.1%.
© (2009) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Wouter A. Soer, Martin J. J. Jak, Andrei M. Yakunin, Maarten M. J. W. van Herpen, and Vadim Y. Banine "Grid spectral purity filters for suppression of infrared radiation in laser-produced plasma EUV sources", Proc. SPIE 7271, Alternative Lithographic Technologies, 72712Y (18 March 2009); https://doi.org/10.1117/12.814231
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Cited by 24 scholarly publications and 2 patents.
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KEYWORDS
Transmittance

Extreme ultraviolet

Infrared radiation

Optical filters

Extreme ultraviolet lithography

Plasma

Reflectivity

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