Lithographic apparatus and device manufacturing method
First Claim
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1. A lithographic apparatus, comprising:
- a radiation system configured to provide a beam of radiation;
a support structure configured to support a patterning device that imparts said beam of radiation with a desired pattern;
a substrate holder configured to hold a substrate;
a projection system configured to project said patterned beam of radiation onto a target portion of said substrate; and
a positioning system configured to maintain at least a first optical element and a second optical element in predetermined positions, said at least first and second optical elements being disposed in said radiation system and/or said illumination system, said positioning system comprising;
at least one position sensor that directly measures a relative position of at least said first optical element relative to said second optical element, wherein said positioning system maintains said first and second optical elements in a predetermined relative position.
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Abstract
In a projection system for EUV, the positions of mirrors are measured and controlled relative to each other, rather than to a reference frame. Relative position measurements may be made by interferometers or capacitive sensors mounted on rigid extensions of the mirrors.
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Citations
16 Claims
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1. A lithographic apparatus, comprising:
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a radiation system configured to provide a beam of radiation;
a support structure configured to support a patterning device that imparts said beam of radiation with a desired pattern;
a substrate holder configured to hold a substrate;
a projection system configured to project said patterned beam of radiation onto a target portion of said substrate; and
a positioning system configured to maintain at least a first optical element and a second optical element in predetermined positions, said at least first and second optical elements being disposed in said radiation system and/or said illumination system, said positioning system comprising;
at least one position sensor that directly measures a relative position of at least said first optical element relative to said second optical element, wherein said positioning system maintains said first and second optical elements in a predetermined relative position. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A device manufacturing method, comprising:
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providing a substrate;
providing a beam of radiation using a radiation system;
imparting a desired pattern onto said beam of radiation;
projecting said patterned beam of radiation onto a target portion of said substrate via a projection system;
wherein a first optical element and a second optical element within said device are maintained in predetermined positions by;
directly measuring the relative positions of said first and second optical elements, and controlling the positions of said first and second optical elements based on the direct measurement of their relative positions.
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11. A lithographic positioning system, comprising:
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at least a first optical element and a second optical element situated in predetermined positions;
at least one position sensor that directly measures a relative position of at least said first optical element relative to said second optical element;
a first actuator and a second actuator;
a first controller and a second controller configured to respectively control said first and second actuators, said first controller being responsive to the measured relative position of said first optical element and said second controller being responsive to the measured relative position of said first and second optical elements;
wherein said first and second actuators operate to maintain said first and second optical elements in a predetermined relative position. - View Dependent Claims (12, 13, 14, 15, 16)
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Specification