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Spectral purification and infrared light recycling in extreme ultraviolet lithography sources

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Author
Abstract

We present the design of a novel collector mirror for laser produced plasma (LPP) light sources to be used in extreme ultraviolet (EUV) lithography. The design prevents undesired infrared (IR) drive laser light, reflected from the plasma, from reaching the exit of the light source. This results in a strong purification of the EUV light, while the reflected IR light becomes refocused into the plasma for enhancing the IR-to-EUV conversion. The dual advantage of EUV purification and conversion enhancement is achieved by incorporating an IR Fresnel zone plate pattern into the EUV reflective multilayer coating of the collector mirror. Calculations using Fresnel-Kirchhoff's diffraction theory for a typical collector design show that the IR light at the EUV exit is suppressed by four orders of magnitude. Simultaneously, 37% of the reflected IR light is refocused back the plasma. (C) 2014 Optical Society of America

Year of Publication
2014
Journal
Optics Express
Volume
22
Issue
7
Number of Pages
8633-8639
Date Published
Apr 7
ISBN Number
1094-4087
DOI
PId
076ccb96c67f51cfb60d44c0253a002e
Alternate Journal
Opt. Express
Label
OA
Journal Article
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