Title:
APPARATUS FOR PROJECTING A REDUCED IMAGE OF A PHOTOMASK USING A SCHWARZSCHILD OBJECTIVE
Document Type and Number:
WIPO Patent Application WO2006086486
Kind Code:
A3
Abstract:
An optical system for projecting an image of a photomask (26) on a substrate (50) , using a Schwarzs child objective includes an excimer laser, beam shaping optics for shaping a laser beam (22) from the laser and a beam-dividing prism (10) . The beam-dividing prism has a dividing-face including four facets (14A, 14B, 14C, 14D) inclined at an angle to each other. The four facets divide the shaped beam into four beam-portions (22A, 22B, 22C, 22D) propagating at an angle to the system axis (18) . The beam-portions overlap at the photomask (26) and mutually diverge into the entrance aperture (33) in the concave mirror (36) of the Schwarzschild objective such that all of the light in the beam portions is incident on the convex mirror (34) of the objective in an annular zone outside of the central obscuration zone of the convex mirror (36) . This essentially eliminates transfer losses normally caused by this obscuration zone .
Inventors:
FERBER JOERG (DE)
SCHMIDT HENNING (DE)
SCHMIDT HENNING (DE)
Application Number:
PCT/US2006/004458
Publication Date:
December 21, 2006
Filing Date:
February 07, 2006
Export Citation:
Assignee:
COHERENT INC (US)
FERBER JOERG (DE)
SCHMIDT HENNING (DE)
FERBER JOERG (DE)
SCHMIDT HENNING (DE)
International Classes:
G03F7/20
Foreign References:
| DE19533314A1 | 1997-03-13 | |||
| US20040036037A1 | 2004-02-26 |
Other References:
PATENT ABSTRACTS OF JAPAN vol. 1995, no. 11 26 December 1995 (1995-12-26)
BJORKHOLM J E ET AL: "REDUCTION IMAGING AT 14 NM USING MULTILAYER-COATED OPTICS: PRINTING OF FEATURES SMALLER THAN 0.1 UM", JOURNAL OF VACUUM SCIENCE AND TECHNOLOGY: PART B, AVS / AIP, MELVILLE, NEW YORK, NY, US, vol. 8, no. 6, 1 November 1990 (1990-11-01), pages 1509 - 1513, XP000169153, ISSN: 1071-1023
BJORKHOLM J E ET AL: "REDUCTION IMAGING AT 14 NM USING MULTILAYER-COATED OPTICS: PRINTING OF FEATURES SMALLER THAN 0.1 UM", JOURNAL OF VACUUM SCIENCE AND TECHNOLOGY: PART B, AVS / AIP, MELVILLE, NEW YORK, NY, US, vol. 8, no. 6, 1 November 1990 (1990-11-01), pages 1509 - 1513, XP000169153, ISSN: 1071-1023
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