Four-mirror extreme ultraviolet (EUV) lithography projection system
First Claim
1. A system for transferring a pattern on a reticle to a substrate, the reticle illuminated with light, the system comprising:
- a dominantly hyperbolic convex mirror positioned to receive the light from the reticle, and reflecting the received light;
a dominantly elliptical concave mirror positioned to receive the light reflected from the hyperbolic mirror, and reflecting the light received from the hyperbolic mirror;
a first substantially spherical convex mirror positioned to receive the light reflected from the elliptical mirror, and reflecting the light received from the elliptical mirror; and
a second approximately spherical concave mirror positioned to receive the light reflected from the first spherical mirror, and reflecting the light to the substrate.
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Accused Products
Abstract
The invention is directed to a four-mirror catoptric projection system for extreme ultraviolet (EUV) lithography to transfer a pattern from a reflective reticle to a wafer substrate. In order along the light path followed by light from the reticle to the wafer substrate, the system includes a dominantly hyperbolic convex mirror, a dominantly elliptical concave mirror, spherical convex mirror, and spherical concave mirror. The reticle and wafer substrate are positioned along the system'"'"'s optical axis on opposite sides of the mirrors. The hyperbolic and elliptical mirrors are positioned on the same side of the system'"'"'s optical axis as the reticle, and are relatively large in diameter as they are positioned on the high magnification side of the system. The hyperbolic and elliptical mirrors are relatively far off the optical axis and hence they have significant aspherical components in their curvatures. The convex spherical mirror is positioned on the optical axis, and has a substantially or perfectly spherical shape. The spherical concave mirror is positioned substantially on the opposite side of the optical axis from the hyperbolic and elliptical mirrors. Because it is positioned off-axis to a degree, the spherical concave mirror has some asphericity to counter aberrations. The spherical concave mirror forms a relatively large, uniform field on the wafer substrate. The mirrors can be tilted or decentered slightly to achieve further increase in the field size.
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Citations
31 Claims
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1. A system for transferring a pattern on a reticle to a substrate, the reticle illuminated with light, the system comprising:
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a dominantly hyperbolic convex mirror positioned to receive the light from the reticle, and reflecting the received light; a dominantly elliptical concave mirror positioned to receive the light reflected from the hyperbolic mirror, and reflecting the light received from the hyperbolic mirror; a first substantially spherical convex mirror positioned to receive the light reflected from the elliptical mirror, and reflecting the light received from the elliptical mirror; and a second approximately spherical concave mirror positioned to receive the light reflected from the first spherical mirror, and reflecting the light to the substrate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A system for transferring a pattern on a reticle to a substrate, the system having an optical axis, the system comprising:
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a first, concave mirror having a radius of curvature of 400 to 600 millimeters, the first mirror positioned from 400 to 600 millimeters from the substrate in a first direction along the system'"'"'s optical axis; a second, convex mirror having a radius of curvature of 300 to 500 millimeters, the second mirror positioned from 200 to 400 millimeters from the first mirror in a second direction along the system'"'"'s optical axis, the second direction opposite to the first direction; a third, concave mirror having a radius of curvature of 900 to 1400 millimeters, the third mirror positioned from 400 to 600 millimeters from the second mirror in the first direction along the system'"'"'s optical axis; and a fourth, convex mirror having a radius of curvature of 2000 to 6000 millimeters, the fourth mirror positioned from 500 to 800 millimeters from the third mirror in the second direction along the system'"'"'s optical axis, and the distance from the fourth mirror to the reticle in a range from 800 to 1500 millimeters in the first direction; wherein the first, second, third and fourth mirrors are decentered between the values of 1 to 5, 0 to -2, 2 to 7, and 1 to 4 millimeters, respectively, along an axis normal to the system'"'"'s optical axis.
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24. A system for transferring a pattern on a reticle to a substrate, the system having an optical axis, the system comprising:
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a first, concave mirror having a radius of curvature of 400 to 600 millimeters, the first mirror positioned from 400 to 600 millimeters from the substrate in a first direction along the system'"'"'s optical axis; a second, convex mirror having a radius of curvature of 300 to 500 millimeters, the second mirror positioned from 200 to 400 millimeters from the first mirror in a second direction along the system'"'"'s optical axis, the second direction opposite to the first direction; a third, concave mirror having a radius of curvature of 900 to 1400 millimeters, the third mirror positioned from 400 to 600 millimeters from the second mirror in the first direction along the system'"'"'s optical axis; and a fourth, convex mirror having a radius of curvature of 2000 to 6000 millimeters, the fourth mirror positioned from 500 to 800 millimeters from the third mirror in the second direction along the system'"'"'s optical axis, and the distance from the fourth mirror to the reticle in a range from 800 to 1500 millimeters in the first direction; wherein the object field at the reticle is decentered between the values of 200 to 250 millimeters along an axis normal to the optical axis.
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25. A system for transferring a pattern on a reticle to a substrate, the system having an optical axis, the system comprising:
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a first, concave mirror having a radius of curvature of 400 to 600 millimeters, the first mirror positioned from 400 to 600 millimeters from the substrate in a first direction along the system'"'"'s optical axis; a second, convex mirror having a radius of curvature of 300 to 500 millimeters, the second mirror positioned from 200 to 400 millimeters from the first mirror in a second direction along the system'"'"'s optical axis, the second direction opposite to the first direction; a third, concave mirror having a radius of curvature of 900 to 1400 millimeters, the third mirror positioned from 400 to 600 millimeters from the second mirror in the first direction along the system'"'"'s optical axis; and a fourth, convex mirror having a radius of curvature of 2000 to 6000 millimeters, the fourth mirror positioned from 500 to 800 millimeters from the third mirror in the second direction along the system'"'"'s optical axis, and the distance from the fourth mirror to the reticle in a range from 800 to 1500 millimeters in the first direction; wherein the first, second, third and fourth mirrors are tilted between the values of 0 to 1, 0 to -1, 0 to 1, 0 to -1 degrees, respectively, about an axis orthogonal to the optical axis.
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26. A system for transferring a pattern on a reticle to a substrate, the system having an optical axis, the system comprising:
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a first, concave mirror having a radius of curvature of 400 to 600 millimeters, the first mirror positioned from 400 to 600 millimeters from the substrate in a first direction along the system'"'"'s optical axis; a second, convex mirror having a radius of curvature of 300 to 500 millimeters, the second mirror positioned from 200 to 400 millimeters from the first mirror in a second direction along the system'"'"'s optical axis, the second direction opposite to the first direction; a third, concave mirror having a radius of curvature of 900 to 1400 millimeters, the third mirror positioned from 400 to 600 millimeters from the second mirror in the first direction along the system'"'"'s optical axis; and a fourth, convex mirror having a radius of curvature of 2000 to 6000 millimeters, the fourth mirror positioned from 500 to 800 millimeters from the third mirror in the second direction along the system'"'"'s optical axis, and the distance from the fourth mirror to the reticle in a range from 800 to 1500 millimeters in the first direction; wherein the reticle is tilted between the values of 0 to -1 degrees relative to an axis normal to the optical axis.
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27. A system for projecting patterned light from a reticle to a substrate, the system comprising:
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a dominantly hyperbolic convex mirror; a dominantly elliptical concave mirror; a dominantly spherical convex mirror; and a dominantly spherical concave mirror, the mirrors, in the stated sequence, for transferring patterned light from the reticle, through said system of mirrors, to the substrate. - View Dependent Claims (28, 29, 30, 31)
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Specification