Large NA projection lens for excimer laser lithographic systems
AssigneeNikon Corporation
InventorRomeo I. Mercado
Life of this patent
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Abstract
An apparatus and method for transferring a pattern on a reticle onto a wafer includes a projection lens system having four groups of lens elements. The projection lens system satisfies the conditions: 0.3<.vertline.f.sub.G2 /L.vertline.<4.46, 1.8<.vertline.f.sub.G3 /L.vertline.<4.8, 0.05<.vertline.f.sub.G2 /f.sub.G3 .vertline.<0.25, 0.77<.vertline.f.sub.G1 /f.sub.G4 .vertline.<1.1, 0.17<f.sub.G4 /F<0.195, 0.14<f.sub.G1 /F<0.191, and having a numerical aperture equal to or greater than 0.60.
Claims20
A projection exposure apparatus for transferring a pattern on a reticle onto a substrate, the apparatus comprising:
- a support for holding a reticle in an object plane;
- a support for holding a substrate in an image plane;
- an illuminating system for illuminating a pattern on the reticle;
- a projection lens system for projecting an image of the pattern on the reticle onto the substrate;
- wherein the projection lens system comprises in order from the object plane to the image plane:
- a first group of lens elements having an overall positive refractive power;
- a second group of lens elements having an overall negative refractive power;
- a third group of lens elements having an overall positive refractive power;
- a fourth group of lens elements having an overall positive refractive power;
- wherein the projection exposure apparatus satisfies the conditions:
- 0.3<.vertline.f.sub.G2 /L.vertline.<0.46 and
- 1.8<.vertline.f.sub.G3 /L.vertline.<4.8,
- where f.sub.G2 is the focal length of the second group of lens elements, f.sub.G3 is the focal length of the third group of lens elements, and L is the axial distance between the object plane and the image plane.
A method of transferring a pattern on a reticle onto a wafer, the method comprising:
- illuminating a pattern on a reticle;
- projecting the pattern through a projection lens system onto a substrate;
- wherein projecting the pattern through a projection lens system includes:
- projecting the pattern through a first group of lens elements having a positive refractive power;
- projecting the pattern through a second group of lens elements having a negative refractive power;
- projecting the pattern through a third group of lens elements having a positive refractive power;
- projecting the pattern through a fourth group of lens elements having a positive refractive power;
- and
- wherein the projection lens system satisfies the conditions:
- 0. 3<.vertline.f.sub.G2 /L.vertline.<0.46 and
- 1.8<.vertline.f.sub.G3 /L.vertline.<4.8,
- where f.sub.G2 is the focal length of the second group of lens elements, f.sub.G3 is the focal length of the third group of lens elements, and L is axial distance between the object plane and the image plane.
Dependencies are inferred from the claim text.