ARRANGEMENT FOR THE SUPPRESSION OF UNWANTED SPECTRAL COMPONENTS IN A PLASMA-BASED EUV RADIATION SOURCE

摘要

The invention is directed to an arrangement for the suppression of unwanted spectral components (‘out-of-band’ radiation, as it is called) in a plasma-based radiation source. The object of the invention is to find a novel possibility for the suppression of unwanted spectral components in radiation exiting from a plasma-based EUV radiation source which permits a simple suppression of out-of-band radiation outside the desired EUV range without requiring costly manufacturing and adjustment of diffraction gratings. This object is met according to the invention in that a filter unit is provided between the plasma and an application location of the EUV radiation, which filter unit has at least one gas curtain comprising at least one rapidly flowing gas whose molecules have no absorption maxima for the desired EUV radiation and intensive absorption maxima for other, unwanted wavelengths that are emitted, at least in the IR region. For the purpose of generating the gas curtain, at least one slit nozzle and an efficient gas sink are arranged laterally opposite one another with respect to an optical axis of the beam bundle in order to limit the gas curtain in a spatially defined manner and to remove it again from the vacuum chambers as completely as possible.