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US 5,969,802 AGranted
Exposure apparatus
AssigneeNikon Corporation
InventorsTetsuo Takahashi, Shigeo Mizoroke, Yasuhiro Omura
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AssigneeNikon Corporation
InventorsTetsuo Takahashi, Shigeo Mizoroke, Yasuhiro Omura
Estimating the term…
An exposure apparatus for transferring a pattern on a mask (M) onto a photosensitive substrate (W) via a projection-optical system can reduce gas fluctuation even if the length of the optical path through gas is relatively long, and even if the diameter of light flux through the gas is relatively large. The projection-optical system satisfies the condition ##EQU1## where .lambda. is a wavelength of exposure light used in the apparatus, .SIGMA.i is a summary of gas sections i in an optical path from the mask to the photosensitive substrate, Li is a length of a gas section i along the optical axis, in m, and Ri is an average of a mask-side diameter and a substrate-side diameter of a light flux in each gas section, the light flux emerging from a maximum image height and advancing within meridional plane, wherein at least one gas section i is filled with helium or neon.
An exposure apparatus with a projection-optical system for transferring an image of a pattern formed on a mask onto a photosensitive substrate, comprising a number of gas sections positioned along an optical axis within an optical path from the mask to the photosensitive substrate, the projection-optical system satisfying the condition:
An exposure apparatus with a projection-optical system for transferring an image of a pattern formed on a mask onto a photosensitive substrate, comprising a reflecting optical element and a number of gas sections positioned along an optical axis, the projection-optical system satisfying the following condition:
Dependencies are inferred from the claim text.