Lithographic apparatus, device manufacturing method and device manufactured thereby
First Claim
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1. A lithographic apparatus comprising:
- a support structure configured to support a patterning device, the patterning device configured to pattern a beam of radiation;
a substrate table configured to hold a substrate;
a projection system configured to project the patterned beam onto a target portion of the substrate; and
a displacement measurement system having a first sensor unit and a second sensor unit and configured to measure a displacement of a moveable object in two degrees of freedom relative to a reference frame, the movable object comprising one of the support structure and the substrate table, whereinthe displacement measurement system further comprises two grid gratings mounted on the reference frame, each grid grating corresponding to one of the first and second sensor units; and
the first and second sensor units are mounted on the moveable object and configured to measure displacements of a respective one of the grid gratings.
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Abstract
The X, Y and Rz positions of a mask stage are measured using two optical encoder-reading heads measuring displacements of respective grid gratings mounted on the mask stage. The grid gratings are preferably provided on cut-away portions of the mask table so as to be coplanar with the pattern on the mask itself. Measurements of the table position in the other degrees of freedom can be measured with capacitive or optical height sensors.
75 Citations
11 Claims
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1. A lithographic apparatus comprising:
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a support structure configured to support a patterning device, the patterning device configured to pattern a beam of radiation; a substrate table configured to hold a substrate; a projection system configured to project the patterned beam onto a target portion of the substrate; and a displacement measurement system having a first sensor unit and a second sensor unit and configured to measure a displacement of a moveable object in two degrees of freedom relative to a reference frame, the movable object comprising one of the support structure and the substrate table, wherein the displacement measurement system further comprises two grid gratings mounted on the reference frame, each grid grating corresponding to one of the first and second sensor units; and the first and second sensor units are mounted on the moveable object and configured to measure displacements of a respective one of the grid gratings. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A lithographic apparatus comprising:
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a support structure configured to support a patterning device, the patterning device configured to pattern a beam of radiation; a substrate table configured to hold a substrate; a projection system configured to project the patterned beam onto a target portion of the substrate; and a displacement measurement system configured to measure a displacement of a moveable object in at least two degrees of freedom relative to a reference frame, the movable object comprising one of the support structure and the substrate table, and the displacement measurement system having a first sensor head and a first sensor unit comprising a pair of sensor heads, wherein the displacement measurement system further comprises a grid grating mounted on the moveable object; and the first sensor head and the first sensor unit are mounted on the reference frame and configured to measure a displacement of the grid grating. - View Dependent Claims (8, 9)
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10. A lithographic apparatus comprising:
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a support structure configured to support a patterning device, the patterning device configured to pattern a beam of radiation; a substrate table configured to hold a substrate; a projection system configured to project the patterned beam onto a target portion of the substrate; and a displacement measurement system having a first sensor unit and a second sensor unit and configured to measure a displacement of a moveable object in two degrees of freedom relative to a reference frame, the movable object comprising one of the support structure and the substrate table, wherein the displacement measurement system further comprises two grid gratings mounted on the moveable object, each grid grating corresponding to one of the first and second sensor units; and the first and second sensor units are mounted on the reference frame and configured to measure displacements of a respective one of the grid gratings, wherein at least one of the two grid gratings include a reference mark detectable by the respective sensor unit to define a reference position of the movable object.
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11. A lithographic apparatus comprising:
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a support structure configured to support a patterning device, the patterning device configured to pattern a beam of radiation; a substrate table configured to hold a substrate; a projection system configured to project the patterned beam onto a target portion of the substrate; and a displacement measurement system configured to measure a displacement of a moveable object in at least two degrees of freedom relative to a reference frame, the movable object comprising one of the support structure and the substrate table, and the displacement measurement system having a first sensor head and a first sensor unit comprising a pair of sensor heads, wherein the displacement measurement system further comprises a grid grating mounted on the reference frame; and the first sensor head and the first sensor unit are mounted on the moveable object and configured to measure a displacement of the grid grating.
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Specification