Projection lens system
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United States of America Patent
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-
Dec 8, 1992
Grant Date -
N/A
app pub date -
Dec 12, 1991
filing date -
Dec 12, 1990
priority date (Note) -
In Force
status (Latency Note)
Importance
Abstract
The present invention relates to a projection lens system well-fit for baking integrated circuit patterns onto silicon wafers using a light source having wavelengths ranging from an ultraviolet wavelength zone to a vacuum ultraviolet wavelength zone. This projection lens system is characterized by comprising a plurality of lens elements including a Fresnel lens element having negative dispersion characteristics, said Fresnel lens being located at a position lying somewhere in said projection lens system with the exception of the pupil thereof and satisfying the following condition: 2h.sub.MAX /3.ltoreq.h. Here h.sub.MAX is the maximum height of a marginal ray in said projection lens system, and h is the height of a marginal ray at the position of said Fresnel lens.
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