METHOD AND APPARATUS FOR MEASURING OVERLAY
First Claim
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1. A method of measuring an overlay, comprising:
- generating an original signal using first and second overlay measurement keys which are spaced apart from each other;
generating a first spectrum signal by performing Fourier transform of the original signal;
generating a second spectrum signal by filtering the first spectrum signal; and
generating a corrected signal by performing inverse Fourier transform of the second spectrum signal.
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Abstract
A method of measuring an overlay includes generating an original signal using first and second overlay measurement keys that are spaced apart from each other, generating a first spectrum signal by performing Fourier transform of the original signal, generating a second spectrum signal by filtering the first spectrum signal, and generating a corrected signal by performing inverse Fourier transform of the second spectrum signal.
7 Citations
21 Claims
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1. A method of measuring an overlay, comprising:
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generating an original signal using first and second overlay measurement keys which are spaced apart from each other; generating a first spectrum signal by performing Fourier transform of the original signal; generating a second spectrum signal by filtering the first spectrum signal; and generating a corrected signal by performing inverse Fourier transform of the second spectrum signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An apparatus for measuring an overlay, comprising:
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a stage on which a wafer that includes first and second overlay measurement keys that are spaced apart from each other is arranged; an original signal generation unit configured to generate an original signal using the first and second overlay measurement keys; a Fourier transform lens set configured to generate a first spectrum signal by performing Fourier transform of the original signal; and a signal analysis unit configured to generate a second spectrum signal by filtering the first spectrum signal and generating a corrected signal by performing inverse Fourier transform of the second spectrum signal. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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20. (canceled)
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21. A method of measuring an overlay, comprising:
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illuminating first and second overlay measurement keys to generate an original signal based on the first and second overlay measurement keys, the first and second overlay measurement keys each including a plurality of bars having a length and a width; generating a first spectrum signal by performing Fourier transform of the original signal, a pitch of the first spectrum signal corresponding to the widths and the lengths of the first and second overlay measurement keys; generating a second spectrum signal by filtering the first spectrum signal; and generating a corrected signal by performing inverse Fourier transform of the second spectrum signal, wherein a distance between the first and second overlay measurement keys along a first direction is shorter than an optical width of the light that illuminates the first and second overlay measurement keys.
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Specification