Measuring Method, Measuring Apparatus, Lithographic Apparatus and Device Manufacturing Method
First Claim
1. A method measuring a position of a mark on a substrate in an optical apparatus, the method comprising:
- providing a mark on the substrate;
providing a measurement optical system comprising an illumination subsystem configured to illuminate the mark with a spot of radiation and a detecting subsystem configured to detect radiation diffracted by the mark;
in a scanning operation moving the substrate and the measurement optical system relative to one another at a first velocity so as to scan the mark with the spot of radiation while detecting and processing signals representing the diffracted radiation to calculate a position of the mark relative to a reference frame of the measurement optical system; and
synchronously with said scanning operation, moving the spot of radiation relative to the reference frame of the measurement optical system at a second velocity, the first and second velocities being related such that the spot scans the mark at a third velocity which is lower than the first velocity while said signals are detected.
1 Assignment
0 Petitions
Accused Products
Abstract
An apparatus (AS) measures positions of marks (202) on a lithographic substrate (W). A measurement optical system comprises illumination subsystem (504) for illuminating the mark with a spot of radiation (206) and as detecting subsystem (580) for detecting radiation diffracted by the mark. The substrate and measurement optical system move relative to one another at a first velocity (vW) so as to scan the mark while synchronously moving the spot of radiation relative to the reference frame (RF) of the measurement optical system at a second velocity (vSPOT). The spot scans the mark at a third velocity (vEFF) which is lower than the first velocity to allow more time for accurate position measurements to be acquired. In one embodiment, an objective lens (524) remains fixed in relation to the reference frame while a moving optical element (562) imparts the movement of the radiation spot relative to the reference frame.
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Citations
19 Claims
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1. A method measuring a position of a mark on a substrate in an optical apparatus, the method comprising:
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providing a mark on the substrate; providing a measurement optical system comprising an illumination subsystem configured to illuminate the mark with a spot of radiation and a detecting subsystem configured to detect radiation diffracted by the mark; in a scanning operation moving the substrate and the measurement optical system relative to one another at a first velocity so as to scan the mark with the spot of radiation while detecting and processing signals representing the diffracted radiation to calculate a position of the mark relative to a reference frame of the measurement optical system; and synchronously with said scanning operation, moving the spot of radiation relative to the reference frame of the measurement optical system at a second velocity, the first and second velocities being related such that the spot scans the mark at a third velocity which is lower than the first velocity while said signals are detected. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An apparatus for measuring positions of marks on a substrate, the apparatus comprising:
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a measurement optical system comprising an illumination subsystem configured to illuminate the mark with a spot of radiation and a detecting subsystem configured to detect radiation diffracted by the mark; a first positioning subsystem configured to control movement of the substrate and measurement optical system relative to one another at a first velocity so as to scan the mark with the spot of radiation while detecting and processing signals representing the diffracted radiation to calculate a position of the mark relative to a reference frame of the measurement optical system; a second positioning subsystem operable synchronously with the first positioning subsystem configured to move the spot of radiation relative to the reference frame of the measurement optical system at a second velocity, the first and second velocities being related such that the spot scans the mark at a third velocity which is lower than the first velocity while said signals are detected. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
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18. A lithographic apparatus arranged to transfer a pattern from a patterning device onto a substrate, the apparatus comprising:
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a substrate table constructed to hold a substrate and an alignment sensor configured to measure the positions of marks on the substrate relative to a reference frame of the lithographic apparatus, wherein the alignment sensor comprises a measuring apparatus having; a measurement optical system comprising an illumination subsystem configured to illuminate the mark with a snot of radiation and a detecting subsystem configured to detect radiation diffracted by the mark; a first positioning subsystem configured to control movement of the substrate and measurement optical system relative to one another at a first velocity so as to scan the mark with the spot of radiation while detecting, and processing signals representing the diffracted radiation to calculate a position of the mark relative to a reference frame of the measurement optical system; a second positioning subsystem operable synchronously with the first positioning subsystem configured to move the spot of radiation relative to the reference frame of the measurement optical system at a second velocity, the first and second velocities being related such that the spot scans the mark at a third velocity which is lower than the first velocity while said signals are detected, and wherein the lithographic apparatus is arranged to control the transfer of a pattern onto the substrate by reference to the positions of marks on the substrate measured using said measuring apparatus.
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19. (canceled)
Specification