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US 6,714,282 B2Granted
Position detecting method optical characteristic measuring method and unit, exposure apparatus, and device manufacturing method
AssigneeNikon Corporation
InventorFuyuhiko Inoue
Life of this patent
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Abstract
An optical characteristic measuring method with which to measure an optical characteristic of an optical system to be examined. The optical characteristic measuring method includes detecting positions of a plurality of features in a picked-up image by repeating a calculating step of image information, a calculating step of comparison feature positions, and a correcting and updating step of current estimated feature positions, until the differences between an initial estimated feature positions and the comparison feature positions become at or below a permissible limit, and calculating an optical characteristic of the optical system to be examined based on the detected positions of the plurality of features.
Claims20
An optical characteristic measuring method for measuring an optical characteristic of an optical system to be examined, the optical characteristic measuring method comprising:
- dividing a wave front of light which has passed through the optical system to be examined, by a predetermined optical system to form an image having a plurality of features;
- picking up the image having the plurality of features;
- calculating an initial estimated feature position of at least one feature out of the plurality of features using a specific algorithm based on the picked-up image;
- calculating image information using a model for the predetermined optical system in view of the feature being formed in a current estimated feature position;
- calculating a comparison feature position using the specific algorithm based on the image information;
- correcting the current estimated feature position by amounts corresponding to differences between the initial estimated feature position and the comparison feature position, so that the current estimated feature position is updated;
- and
- performing the calculating of the image information, the calculating of the comparison feature position, and the correcting and updating of the current estimated feature position, until the differences between the initial estimated feature position and the comparison feature position become at or below the permissible limit, and
- calculating an optical characteristic of the optical system to be examined in consideration of the current estimated feature position for which the differences between the initial estimated feature position and the comparison feature position become at or below the permissable limit.
6 more elements
An optical characteristic measuring unit which measures an optical characteristic of an optical system to be examined, the optical characteristic measuring unit comprising:
- a wave-front dividing device which is arranged on an optical path of light passing through the optical system to be examined, divides a wave front of the light passing through the optical system to be examined, and forms an image having a plurality of features;
- a pick-up unit which is arranged a predetermined distance apart from the wave-front dividing device and picks up the image having the plurality of features;
- a position detecting unit connected to the pick-up unit, which detects positions of the plurality of features in the picked-up image,
- wherein the position detecting unit calculates an initial estimated feature position of at least one feature out of the plurality of features using a specific algorithm based on the picked-up image;
- calculates image information using a model for the predetermined optical system in view of the feature being formed in a current estimated feature position;
- calculates a comparison feature position using the specific algorithm based on the image information;
- corrects the current estimated feature position by amounts corresponding to differences between the initial estimated feature position and the comparison feature position, so that the current estimated feature position is updated;
- and performs the calculating of the image information, the calculating of the comparison feature position, and the correcting and updating of the current estimated feature position, until the differences between the initial estimated feature position and the comparison feature position become at or below a permissible limit, and
- an optical characteristic calculating unit connected to the position detecting unit, which calculates an optical characteristic of the optical system to be examined in consideration of the current estimated feature position for which the differences between the initial estimated feature position and the comparison feature position become at or below the permissable limit.
6 more elements
An exposure apparatus which, by illuminating a substrate with exposure light, transfers a predetermined pattern onto a substrate, comprising:
- an exposure apparatus main body which comprises a projection optical system arranged on an optical path of the exposure light;
- a wave-front dividing device which is arranged on an optical path of light passing through the projection optical system, divides a wave front of the light passing through the projection optical system, and forms an image having a plurality of features;
- a pick-up unit which is arranged a predetermined distance apart from the wave-front dividing device and picks up the image having the plurality of features;
- a position detecting unit connected to the pick-up unit, which detects positions of the plurality of features in the picked-up image,
- wherein the position detecting unit calculates an initial estimated feature position of at least one feature out of the plurality of features using a specific algorithm based on the picked-up image;
- calculates image information using a model for the predetermined optical system in view of the feature being formed in a current estimated feature position;
- calculates a comparison feature position using the specific algorithm based on the image information;
- corrects the current estimated feature position by amounts corresponding to differences between the initial estimated feature position and the comparison feature position, so that the current estimated feature position is updated;
- and performs the calculating of the image information, the calculating of the comparison feature position, and the correcting and updating of the current estimated feature position, until the difference between the initial estimated feature position and the comparison feature position become at or below a permissible limit, and
- an optical characteristic calculating unit connected to the position detecting unit, which calculates an optical characteristic of the projection optical system in consideration of the current estimated feature position for which the differences between the initial estimated feature position and the comparison feature position become at or below the permissable limit.
7 more elements
Dependencies are inferred from the claim text.