Objective with birefringent lenses

US6992834B2 · kind B2 · utility

Assignee

• Carl Zeiss SMT GmbH · DE

Inventors

• Michael Totzeck · Schwäbisch Gmünd, DE
• Vladimer Kamenov · Oberkochen, DE
• Daniel Kraehmer · Aalen, DE
• Wilhelm Ulrich · Aalen, DE

Key dates

• Filing date: Mar 2, 2005
• Grant date: Jan 31, 2006
• Expiry date: Mar 2, 2025

Classification

• Technology area (CPC G): Physics
• CPC primary: G03F7/70966
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

Objective (1, 601), in particular a projection objective for a microlithography projection apparatus, with first birefringent lenses (L108, L109, L129, L130) and with second birefringent lenses (L101–L107, L110–L128). The first lenses (L108, L109, L129, L130) are distinguished from the second lenses (L101–L107, L110–L128) by the lens material used or by the material orientation. After passing through the first lenses (L108, L109, L129, L130) and the second lenses (L101–L107, L110–L128), an outer aperture ray (5, 7) and a principal ray (9) are subject to optical path differences for two mutually orthogonal states of polarization. The difference between these optical path differences is smaller than 25% of the working wavelength. In at least one first lens (L129, L130), the aperture angle of the outer aperture ray (5, 7) is at least 70% of the largest aperture angle occurring for said aperture ray in all of the first lenses (L108, L109, L129, L130) and second lenses (L101–L107, L110–L128). This arrangement has the result that the first lenses (L108, L109, L129, L130) have a combined material volume of no more than 20% of the combined total material volume of the first lenses (L108, L…