Mirror projection system for a scanning lithographic projection apparatus, and lithographic apparatus comprising such a system
AssigneeKoninklijke Philips Electronics N.V.
InventorJosephus J.M. Braat
Life of this patent
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Abstract
A mirror projection system for use in a step-and-scan lithographic projection apparatus, in which a mask pattern (15) is repetitively scan-imaged on a number of areas of a substrate (20) by means of a beam (b) of EUV radiation having a cross-section shaped as a segment of a ring, has six imaging mirrors (5-10). The design is such that no intermediate image is formed and the system has a negative magnification. When using this projection system in a scanning apparatus, the mask and the substrate move in opposite directions during scanning, which is advantageous from a mechanical point of view.
Claims6
A mirror projection system for use in a step-and-scan lithographic projection apparatus for imaging a mask pattern, present in a mask, on a substrate by means of a beam of EUV radiation, which beam has a circular segment-shaped cross-section, said projection system being constituted by six imaging mirrors having ordinal numbers 1-6 from the object side to the image side, the second, the third and the sixth mirror being concave and the fifth mirror being convex, characterized in that the first and the fourth mirror are convex.
A lithographic apparatus for step-and-scan imaging of a mask pattern, present in a mask, on a number of areas of a substrate, which apparatus comprises an illumination unit with a source for EUV radiation, a mask holder for accommodating a mask, a substrate holder for accommodating a substrate, and a projection system, characterized in that the projection system is a mirror projection system as claimed in any one of the preceding claims.
Dependencies are inferred from the claim text.