Method for improving the imaging properties of a projection objective for a microlithographic projection exposure apparatus

US7456933B2 · kind B2 · utility

Assignee

• Carl Zeiss SMT GmbH · DE

Inventors

• Ulrich Wegmann · Oberkochen, DE
• Vladimir Kamenov · Oberkochen, DE
• Thomas Muelders · Dresden, DE
• Toralf Gruner · Hennef (Sieg), DE
• Markus Mengel · Heidenheim, DE

Key dates

• Filing date: Sep 8, 2005
• Grant date: Nov 25, 2008
• Expiry date: Nov 9, 2026

Classification

• Technology area (CPC G): Physics
• CPC primary: G03F7/70591
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

In a method for improving the imaging properties of a projection objective of a microlithographic projection exposure apparatus, an appropriate illumination angle distribution adapted to a mask (24; 224) to be projected is selected. Then locations (40a, 40b; 60a, 60b; 80a, 80b, 80c) in an exit pupil of the projection objective (20), which are illuminated under these conditions by projection light during a projection of the mask, are determined. For at least one image point, an actual value of an imaging quantity, e.g. a wavefront profile or a polarization state, is determined that influences the imaging properties of the projection objective. Finally, corrective measures are calculated such that the actual value of the imaging quantity approximates a desired value at these locations. In this last step, however, deviations of the actual value from the desired value are taken into account exclusively at said locations illuminated in the exit pupil.