Title:
VARIABLE NUMERICAL APERTURE LARGE-FIELD UNIT-MAGNIFICATION PROJECTION SYSTEM
Document Type and Number:
WIPO Patent Application WO2004061487
Kind Code:
A3
Abstract:
An optical system for projection photolithography is disclosed. The optical system is a modified Dyson system capable of imaging a large field over both a narrow and a broad spectral range. The optical system includes a positive lens group having a positive subgroup of elements that includes at least a piano-convex element and a negative subgroup that includes at least a negative meniscus element. The lens subgroups are separated by a small air space. The positive and negative subgroups constitute a main lens group arranged adjacent to but spaced apart from a concave mirror along the mirror axis. The system also includes a variable aperture stop so that the system has a variable NA. A projection photolithography system that employs the optical system is also disclosed.
Inventors:
MERCADO ROMEO I
Application Number:
PCT/US2003/041527
Publication Date:
January 13, 2005
Filing Date:
December 31, 2003
Export Citation:
Assignee:
ULTRATECH STEPPER INC (US)
International Classes:
G02B17/08; (IPC1-7): G02B17/00; G03B27/42
Foreign References:
| US6381077B1 | 2002-04-30 | |||
| US6312134B1 | 2001-11-06 | |||
| US6142641A | 2000-11-07 |
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