Symmetrical objective having four lens groups for microlithography

US7697211B2 · kind B2 · utility

Assignee

• Carl Zeiss SMT GmbH · DE

Inventors

• David Shafer · Fairfield, US
• Aurelian Dodoc · Heidenheim an der Brenz, DE
• Johannes Zellner · Aalen, DE
• Heiko Feldmann · Aalen, DE
• Wilhelm Ulrich · Aalen, DE
• Holger Walter · Aalen, DE
• Ulrich Loering · Schwäbisch Gmünd, DE
• Daniel Kraehmer · Aalen, DE
• Gerhard Fuerter · Ellwangen, DE

Key dates

• Filing date: Oct 23, 2008
• Grant date: Apr 13, 2010
• Expiry date: Oct 23, 2028

Classification

• Technology area (CPC G): Physics
• CPC primary: G03F7/70241
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

The invention features a system for microlithography that includes a mercury light source configured to emit radiation at multiple mercury emission lines, a projection objective positioned to receive radiation emitted by the mercury light source, and a stage configured to position a wafer relative to the projection objective. During operation, the projection objective directs radiation from the light source to the wafer, where the radiation at the wafer includes energy from more than one of the emission lines. Optical lens systems for use in said projection objective comprise four lens groups, each having two lenses comprising silica, the first and second lens groups on one hand and the third and fourth lens groups on the other hand are positioned symmetrically with respect to a plane perpendicular to the optical axis of said lens system.