| 摘要 |
<p>An illumination optical unit for EUV projection lithography serves for guiding illumination light (16) towards an illumination field, in which a lithography mask can be arranged. The illumination optical unit has a first facet mirror having a plurality of individual mirrors (26). The latter predefine illumination channels (43) for guiding illumination light partial beams (16i) towards the illumination field. A second facet mirror of the illumination optical unit is disposed downstream of the first facet mirror and has a plurality of facets (34). The latter respectively contribute to the imaging of a group (24a) of the individual mirrors (26) of the first facet mirror into the object field via a group-mirror illumination channel (35). The latter comprises the individual-mirror illumination channels (43) of the individual-mirror group (24a). Images of the different individual-mirror groups (24a) are superimposed on one another in the object field (5) via the assigned group-mirror illumination channels (35). The individual mirrors (26) of the individual-mirror groups (24a) are arranged such that imaging aberrations which occur depending on the respective assignment of the individual-mirror groups (24a) of the first facet mirror to the facets (34) of the second facet mirror during the imaging of the individual-mirror groups (24a) into the object field are at least partly compensated for. This results in an illumination optical unit which provides an optimized superimposition of the illumination light guided via different illumination channels in the illumination field.</p> |
