Projection objective of a microlithographic projection exposure apparatus

US7982969B2 · kind B2 · utility

Assignee

• Carl Zeiss SMT GmbH · DE

Inventors

• Karl-Heinz Schuster · Oberkochen, DE
• Heiko Feldmann · Aalen, DE
• Toralf Gruner · Hennef (Sieg), DE
• Michael Totzeck · Schwäbisch Gmünd, DE
• Wilfried Clauss · Lörrach, DE
• Susanne Beder · Aalen, DE
• Daniel Kraehmer · Aalen, DE
• Olaf Dittmann · Bopfingen, DE

Key dates

• Filing date: Dec 9, 2008
• Grant date: Jul 19, 2011
• Expiry date: Dec 21, 2028

Classification

• Technology area (CPC G): Physics
• CPC primary: G03F7/70308
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A projection objective of a microlithographic projection exposure apparatus has a high index refractive optical element with an index of refraction greater than 1.6. This element has a volume and a material related optical property which varies over the volume. Variations of this optical property cause an aberration of the objective. In one embodiment at least 4 optical surfaces are provided that are arranged in at least one volume which is optically conjugate with the volume of the refractive optical element. Each optical surface comprises at least one correction means, for example a surface deformation or a birefringent layer with locally varying properties, which at least partially corrects the aberration caused by the variation of the optical property.