Patent · US Expired

Objective with crystal lenses

US7239447B2 · kind B2 · utility

2Cited by

34References

33Claims

0Family size

Assignee

Carl Zeiss SMT GmbH · DE

Inventors

Aksel Goehnermeier · Aalen, DE
Alexandra Pazidis · Aalen, DE
Birgit Kuerz · Aalen, DE
Christoph Zaczek · Heubach, DE
Daniel Kraehmer · Aalen, DE

Key dates

Filing date	Sep 1, 2004
Grant date	Jul 3, 2007
Priority date	—
Expiry date	Sep 1, 2024

Classification

Technology area (CPC G)Physics
CPC primaryG03F7/70966
WIPO fieldOptics
WIPO sectorInstruments

Abstract

An objective, in particular a projection objective for a microlithography projection-exposure installation, with at least one fluoride crystal lens is disclosed. A reduction in the detrimental influence of birefringence is achieved if this lens is a (100)-lens with a lens axis which is approximately perpendicular to the {100} crystallographic planes or to the crystallographic planes equivalent thereto of the fluoride crystal. A further reduction in the detrimental influence of birefringence is obtained by covering an optical element with a compensation coating.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.