Differential critical dimension and overlay metrology apparatus and measurement method
First Claim
1. An apparatus for measuring a dimension on a substrate comprising:
- a source of radiation for illuminating said target pattern;
collection optics configured to collect said one or more non-zeroth orders along said primary direction and to image said target pattern along said substantially orthogonal direction; and
a detector array configured to detect spatial variations of said one or more non-zeroth orders from said collection optics along said substantially orthogonal direction and along said primary direction.
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Abstract
A method is described for measuring a dimension on a substrate, wherein a target pattern is provided with a nominal characteristic dimension that repeats at a primary pitch of period P, and has a pre-determined variation orthogonal to the primary direction. The target pattern formed on the substrate is then illuminated so that at least one non-zero diffracted order is detected. The response of the non-zero diffracted order to variation in the printed characteristic dimension relative to nominal is used to determine the dimension of interest, such as critical dimension or overlay, on the substrate. An apparatus for performing the method of the present invention includes an illumination source, a detector for detecting a non-zero diffracted order, and means for positioning the source relative to the target so that one or more non-zero diffracted orders from the target are detected at the detector.
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Citations
8 Claims
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1. An apparatus for measuring a dimension on a substrate comprising:
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a source of radiation for illuminating said target pattern; collection optics configured to collect said one or more non-zeroth orders along said primary direction and to image said target pattern along said substantially orthogonal direction; and a detector array configured to detect spatial variations of said one or more non-zeroth orders from said collection optics along said substantially orthogonal direction and along said primary direction. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification