Open AccessStructured Mo/Si multilayers for IR-suppression in laser-produced EUV light sources
Author(s) -
Marcus Trost,
Sven Schröder,
Angela Duparré,
Stefan Risse,
Torsten Feigl,
Uwe D. Zeitner,
Andreas Tünnermann
Publication year - 2013
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.21.027852
Subject(s) - extreme ultraviolet lithography , extreme ultraviolet , optics , materials science , optoelectronics , laser , lithography , wavelength , diffraction efficiency , diffraction grating , grating , physics
Laser produced plasma sources are considered attractive for high-volume extreme-ultraviolet (EUV) lithography because of their high power at the target wavelength 13.5 nm. However, besides the required EUV light, a large amount of infrared (IR) light from the CO 2 drive laser is scattered and reflected from the plasma as well as from the EUV mirrors in the optical system. Since these mirrors typically consist of molybdenum and silicon, the reflectance at IR wavelengths is even higher than in the EUV, which leads to high energy loads in the optical system. One option to reduce this is to structure the EUV multilayer, in particular the collector mirror, with an IR grating that has a high IR-suppression in the zeroth order. In this paper, the characterization of such an optical element is reported, including the IR-diffraction efficiency, the EUV performance (reflectance and scattering), and the relevant surface roughness. The measurement results are directly linked to the individual manufacturing steps.