Displacement measurement system, lithographic apparatus, displacement measurement method and device manufacturing method
First Claim
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1. A displacement measurement system configured to measure a displacement of a component relative to a reference component, comprising:
- first, second, third and fourth targets, each mounted to the reference component and arranged such that a target surface of each target is substantially parallel to a reference plane; and
first, second, third and fourth displacement sensors, each arranged to measure the displacement of a respective part of the component relative to the target surface of a respective target;
wherein said first and third displacement sensors are configured to measure the displacement of first and third parts of the component relative to the target surfaces of said first and third targets, respectively, along a direction substantially parallel to a first direction that lies within said reference plane; and
said second and fourth displacement sensors are configured to measure the displacement of second and fourth parts of the component relative to the target surfaces of said second and fourth targets, respectively, along a direction substantially parallel to a second direction that lies within said reference plane and is substantially orthogonal to said first direction.
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Abstract
A displacement measurement system, in particular for measuring the displacement of a substrate table in a lithographic apparatus relative to a reference frame is presented. The displacement measure system includes a plurality of displacement sensors mounted to the substrate table and a target associated with each displacement sensor mounted to the reference frame.
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Citations
24 Claims
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1. A displacement measurement system configured to measure a displacement of a component relative to a reference component, comprising:
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first, second, third and fourth targets, each mounted to the reference component and arranged such that a target surface of each target is substantially parallel to a reference plane; and
first, second, third and fourth displacement sensors, each arranged to measure the displacement of a respective part of the component relative to the target surface of a respective target;
wherein said first and third displacement sensors are configured to measure the displacement of first and third parts of the component relative to the target surfaces of said first and third targets, respectively, along a direction substantially parallel to a first direction that lies within said reference plane; and
said second and fourth displacement sensors are configured to measure the displacement of second and fourth parts of the component relative to the target surfaces of said second and fourth targets, respectively, along a direction substantially parallel to a second direction that lies within said reference plane and is substantially orthogonal to said first direction. - 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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a substrate table constructed to support a substrate;
a first displacement measuring system configured to measure a displacement of the substrate table relative to a reference component during a process to transfer a pattern onto the substrate, the first displacement measuring system comprising at least one target mounted to the reference component and at least one displacement sensor configured to measure the displacement of at least a part of the substrate table relative to the at least one target; and
a second displacement measuring system configured to measure a displacement of the substrate table relative to a base frame of the lithographic apparatus, at least during a part of a substrate table return movement, in which the substrate table is moved from a position at which the pattern is transferred to the substrate, to an unload position, at which a substrate is unloaded from the substrate table. - View Dependent Claims (19, 20, 21, 23)
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22. A method of measuring a displacement of a component relative to a reference component, the method comprising:
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measuring a displacement of a respective part of the component relative to a target surface of a first, second, third and fourth target using first, second, third and fourth displacement sensors, respectively, the first, second, third and fourth targets mounted to the reference component and arranged such that the target surface of each of said first, second, third and fourth targets is substantially parallel to a reference plane;
wherein said first and third displacement sensors measure a displacement of the first and third parts of the component relative to the target surface of the first and third targets, respectively, along a direction substantially parallel to a first direction that lies within said reference plane; and
wherein said second and fourth displacement sensors measure a displacement of the second and fourth parts of the component relative to the target surfaces of the second and fourth targets, respectively, along a direction substantially parallel to a second direction that lies within said reference plane and is substantially orthogonal to said first direction.
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24. A device manufacturing method comprising:
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transferring a pattern from a patterning device onto a substrate, the substrate being supported on a substrate table during the transferring;
measuring a displacement of the substrate table relative to a reference component during said transferring using a displacement measuring system comprising at least one target mounted to the reference component and at least one displacement sensor, the at least one displacement sensor configured to measure the displacement of at least a part the substrate table relative to the at least one target; and
measuring a displacement of the substrate table relative to a base frame of the lithographic apparatus, at least during a part of a substrate table return movement, in which the substrate table is moved from a position in which the pattern is transferred onto the substrate, to an unload position, at which the substrate is unloaded from the table.
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Specification