ILLUMINATION OPTICAL SYSTEM FOR EUV PROJECTION LITHOGRAPHY

摘要

An illumination optical system for EUV projection lithography for illuminating an illumination field, in which an object field of a following imaging optical system can be arranged, has a first facet mirror with a plurality of first facets (71) for the reflective guidance of part bundles of a bundle of EUV illumination light (3). A downstream second facet mirror (10) with a plurality of second facets (11) is used for the reflective guidance of the part bundles (31; 31') reflected by the first facets (71), so object field illumination channels, to which, in each case, a first (71) and a second (111; 111') facet is allocated in each case, are predetermined by the first facets (7) and the second facets (111; 111') allocated by means of the reflected bundle guidance. The reflection faces of at least some of the first facets (71) are tiltable in each case between at least one illumination tilting position to guide the part bundle along an object field illumination channel (31; 31') in the direction of one of the second facets (111; 111') and at least one switch-off tilting position to guide the part bundle in the direction of a switch-off beam path (30) not impinging on the object field. The direction of the switch-off beam path (30) differs from the direction of the object field illumination channel (31; 31'). In addition, methods for predetermining a set of switch-off tilting positions of the tiltable first facets (7) are disclosed. The result is an illumination optical system, with which a fine adjustment of illumination settings to be predetermined for the illumination of the illumination field is possible.