Patent ID: 8147647
Filing Date: 2012-04-03
Classification: B08B,G03F,H05H

Abstract:
1. An arrangement for cleaning optical surfaces of reflection optics which are arranged in a plasma-based radiation source or in an exposure device arranged downstream and which are contaminated by debris particles emitted by a hot plasma of the radiation source, comprising: gas feeds being arranged at the edge of the optical surfaces for streaming in at least one gas along the optical surfaces, which gas is reactive for the debris particles, and gas radicals can be generated from the introduced gas by electric discharges with the participation of electrode areas that are associated with at least a portion of the optical surface in parallel planes, said gas radicals forming gaseous compounds with debris particles generated by plasma; vacuum pumps being provided in the radiation source for sucking up these debris particles; a closed optical surface being formed in each instance either itself as a surface electrode or is provided with a back surface electrode parallel to the optical surface; a surface electrode that is formed approximately parallel to the optical surface being arranged over the optical surface as a counter-electrode; at least one dielectric barrier layer being arranged between the surface electrodes over the entire surface of one of the oppositely located surface electrodes; and the oppositely located surface electrodes being connected to an AC voltage source having an AC voltage in the Hz to kHz range so that a cold plasma is generated in the gas flow between the surface electrodes by ongoing dielectrically impeded discharges which are evenly distributed spatially and gas radicals are continuously provided for cleaning the optical surfaces.