Microlithographic illumination method and a projection lens for carrying out the method

US6728043B2 · kind B2 · utility

Assignee

• Carl Zeiss Semiconductor Manufacturing Technologies AG · DE

Inventors

• Toralf Gruner · Hennef (Sieg), DE
• Manfred Maul · Aalen, DE
• Rudolf Von Buenau · Jena, DE

Key dates

• Filing date: May 17, 2002
• Grant date: Apr 27, 2004
• Expiry date: May 17, 2022

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S359/90
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A microlithographic illumination method for imaging a pattern arranged in an object plane of a projection lens onto an image plane of the projection lens, under which a special means for optically correcting the optical path lengths of s-polarized and p-polarized light such that light beams of both polarizations will either traverse essentially the same optical path length between the object plane and the image plane or any existing difference in their optical path lengths will be retained, largely independently of their angles of incidence on the image plane, which will allow avoiding contrast variations due to pattern orientation when imaging finely structured patterns, is disclosed. The contrast variations may be caused by uncorrected projection lenses due to their employment of materials that exhibit stress birefringence and/or coated optical components, such as deflecting mirrors, that are used at large angles of incidence.