Lithographic apparatus, overlay detector, device manufacturing method, and device manufactured thereby
First Claim
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1. A measurement device comprising:
- a first object having a first pattern;
a second object having a second pattern corresponding to the first pattern;
a projection system configured to project an image of the first pattern onto the second pattern; and
a detector configured to measure an amplitude of at least one order of a diffraction pattern resulting from an interference of the second pattern and the projected image.
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Abstract
A device according to one embodiment of the invention may be applied to measure the overlay (e.g. as a machine performance number) quickly and over an expanded range of locations (possibly everywhere) on a wafer. One method using such a device includes measuring the amplitude of a diffraction order of a diffraction pattern that results from interference between a pattern on wafer level and a pattern that is projected on the pattern on wafer level. The pattern that is projected may be present, for example, at reticle level.
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Citations
28 Claims
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1. A measurement device comprising:
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a first object having a first pattern;
a second object having a second pattern corresponding to the first pattern;
a projection system configured to project an image of the first pattern onto the second pattern; and
a detector configured to measure an amplitude of at least one order of a diffraction pattern resulting from an interference of the second pattern and the projected image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A lithographic apparatus comprising:
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an illumination system configured to provide a beam of radiation;
a support structure configured to support a patterning structure, the patterning structure configured to impart the beam with a pattern in its cross-section;
a substrate table configured to hold a substrate;
a projection system configured to project the patterned beam onto a target portion of the substrate;
a first object having at least a first pattern;
a second object having a second pattern corresponding to said first pattern; and
a detector, wherein the illumination system is configured to illuminate the first pattern, and wherein the projection system is configured to project a patterned beam including an image of the first pattern onto the second pattern, and wherein the detector is configured to measure an amplitude of at least one order of a diffraction pattern resulting from interference between the second pattern and the projected image. - View Dependent Claims (19, 20)
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21. A method for measurement, said method comprising:
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illuminating a first object having at least a first pattern;
projecting an image of the first pattern onto a second object having a second pattern corresponding to the first pattern; and
measuring an amplitude of at least one order of a diffraction pattern resulting from interference between the second pattern and the projected image. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28)
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Specification