Patent ID: 8514372
Filing Date: 2013-08-20
Classification: G03F

Abstract:
1. A method for setting an illumination geometry for an illumination optical unit for EUV projection lithography for guiding illumination light toward an object field in which a lithography mask can be arranged, the illumination optical unit comprising a first facet mirror having a multiplicity of individual mirrors which can be switched between at least two tilting positions and which provide individual-mirror illumination channels for guiding illumination light partial beams toward the object field, the illumination optical unit comprising a second facet mirror downstream of the first facet mirror in the beam path of the illumination light and having a plurality of facets which each contribute to the imaging of a group of the individual mirrors of the first facet mirror into the object field via a group-mirror illumination channel, wherein the images of the individual mirrors of a respective individual-mirror group in the object field complement one another for illumination of the entire object field, the method comprising: predefining a desired illumination geometry; and varying tilting angles of the individual mirrors within one and the same individual-mirror group, wherein the individual mirrors: wherein tilting position distributions of the individual mirrors within the individual-mirror group are permitted in which at least one first tilting position and at least one further tilting position are present until an actual illumination geometry corresponds to the desired illumination geometry within predefined tolerances.