Facet mirror suitable for use as first facet mirror for illumination optical unit for projection lithography

Abstract

A faceted mirror (6) for an illumination optical unit for projection lithography is adapted to be used as a first faceted mirror such that individual mirror groups of faceted mirrors (6) are imaged as first facets at least into a partial field of an object field of the illumination optical unit with the assistance of a transmission optical unit, an object may be disposed in the object field and displaced through the object field in an object displacement direction (y) during the projection exposure. The facet mirror (6) has an array configuration of individual mirror units (26), wherein each of the individual mirror units (26) is implemented as a sub-array of NxM individual mirrors (21). The faceted mirror (6) comprises at least two pre-tilt types (321, 322) of individual mirror units (26). The first pre-tilt type (321) comprises individual mirror units (26) having, in the neutral position, a first pre-tilt angle with respect to a base tilt angle specified by the carrier geometry of the faceted mirror (6). The second pre-tilt type (322) includes individual mirror units (26) having a second pre-tilt angle. The pre-tilt angles of the different pre-tilt types (321, 322) are different from each other. This results in faceted mirrors that have loose requirements for tilting actuator systems for tilting individual ones of the faceted mirrors.

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