Measurement of the position of a radiation beam spot in lithography
First Claim
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1. A lithographic apparatus, comprising:
- a programmable patterning device, configured to provide a plurality of radiation beams;
a projection system, configured to project the plurality of radiation beams onto a substrate to form respective spots of radiation; and
a radiation spot measurement system, comprising;
a target, onto which the spots of radiation may be projected for a spot measurement process, the target comprising a plurality of measurement targets;
a radiation detector, configured to detect radiation from one of the spots of radiation that has been projected onto the measurement target;
an actuator system configured to control the position of the radiation detector relative to the plurality of measurement targets such that, at different respective positions, it can detect radiation that has been projected onto a different measurement target of the plurality of measurement targets; and
a controller, configured to receive information from the radiation detector and, based on the information, to determine at least the position of the spot of radiation relative to an intended position of the spot of radiation on the target in a plane substantially parallel to a surface of the target.
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Abstract
A radiation spot measurement system for a lithographic apparatus, the system having a target onto which a radiation system of the lithographic apparatus may project spots of radiation for a measurement process, the target having a measurement target. The system further includes a radiation detector to detect radiation from one of the spots, and a controller to receive information from the radiation detector and to determine the position of the spot of radiation relative to an intended position of the spot of radiation.
78 Citations
20 Claims
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1. A lithographic apparatus, comprising:
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a programmable patterning device, configured to provide a plurality of radiation beams; a projection system, configured to project the plurality of radiation beams onto a substrate to form respective spots of radiation; and a radiation spot measurement system, comprising; a target, onto which the spots of radiation may be projected for a spot measurement process, the target comprising a plurality of measurement targets; a radiation detector, configured to detect radiation from one of the spots of radiation that has been projected onto the measurement target; an actuator system configured to control the position of the radiation detector relative to the plurality of measurement targets such that, at different respective positions, it can detect radiation that has been projected onto a different measurement target of the plurality of measurement targets; and a controller, configured to receive information from the radiation detector and, based on the information, to determine at least the position of the spot of radiation relative to an intended position of the spot of radiation on the target in a plane substantially parallel to a surface of the target. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17, 18)
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16. A method for measuring a radiation beam spot position in a lithographic apparatus that comprises a programmable patterning device to provide a plurality of radiation beams and a projection system to project the plurality of radiation beams onto a substrate to form respective spots of radiation, the method comprising:
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projecting the spots of radiation onto a target comprising a plurality of measurement targets; using a radiation detector to detect radiation from one of the spots of radiation that has been projected onto the measurement target; controlling the position of the radiation detector, using an actuator system, relative to the plurality of measurement targets such that, at different respective positions, it can detect radiation that has been projected onto a different measurement target of the plurality of measurement targets; and determining at least the position of the spot of radiation relative to an intended position of the spot of radiation in a plane substantially parallel to a surface of the target based on information from the radiation detector.
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19. A lithographic apparatus, comprising:
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a programmable patterning device, configured to provide a plurality of radiation beams; a projection system, configured to project the plurality of radiation beams onto a substrate to form respective spots of radiation; and a radiation spot measurement system, comprising; a target, onto which the spots of radiation may be projected for a spot measurement process, the target comprising a measurement target, the measurement target comprising first, second and third sections, the first and third sections each comprising a grating and the second section comprising a window; a radiation detector configured to detect radiation from one of the spots of radiation that has been projected onto the measurement target, the radiation detector comprising a radiation intensity sensor configured to detect the intensity of radiation from the spot and the window configured to permit the spot of radiation to be directed to the radiation detector; and a control system configured to provide relative movement between the spot of radiation and the first, second and third sections such the spot scans across the first, second and third sections, configured to control the programmable patterning device such that the beam of radiation providing the spot of radiation has a substantially constant intensity when it scans across the first and third sections and has a varying intensity at a reference position when the spot of radiation scans across the second section, and configured to determine at least the position of the spot of radiation relative to an intended position of the spot of radiation on the target in a plane substantially parallel to a surface of the target based on the timing and/or phase of first, second and third signals from the radiation detector that correspond to the spot of radiation being projected onto the first, second and third sections respectively.
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20. A lithographic apparatus, comprising:
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a programmable patterning device, configured to provide a plurality of radiation beams; a projection system, configured to project the plurality of radiation beams onto a substrate to form respective spots of radiation; and a radiation spot measurement system, comprising; a target, onto which the spots of radiation may be projected for a spot measurement process, the target comprising a measurement target, the measurement target comprising a plurality of sections, each section comprising a respective grating; a radiation detector configured to detect radiation from one of the spots of radiation that has been projected onto the measurement target, the radiation detector comprising a radiation intensity sensor configured to detect the intensity of radiation from the spot; and a control system configured to provide relative movement between the spot of radiation and the plurality of sections such the spot scans across the sections, configured to control the programmable patterning device such that the beam of radiation providing the spot of radiation has a varying intensity at a substantially constant frequency at the point at which it is projected onto the target, and configured to determine at least the position of the spot of radiation relative to an intended position of the spot of radiation on the target in a plane substantially parallel to a surface of the target based on respective signals from the radiation detector corresponding to the spot of radiation being projected at the plurality of sections of the measurement target.
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Specification