OVERLAY METROLOGY BY PUPIL PHASE ANALYSIS
First Claim
1. A method for measuring overlay utilizing pupil phase information, comprising:
- measuring a first phase distribution across a pupil plane of a portion of illumination reflected from a first overlay target of a semiconductor wafer, wherein the first overlay target is fabricated to have a first intentional overlay;
measuring a second phase distribution across the pupil plane of a portion of illumination reflected from a second overlay target of the semiconductor wafer, wherein the second overlay target is fabricated to have a second intentional overlay, wherein the second intentional overlay is along a direction opposite to the first intentional overlay, wherein the first intentional overlay and the second intentional overlay have substantially the same magnitude;
determining a first phase tilt associated with a sum of the first phase distribution and the second phase distribution;
determining a second phase tilt associated with a difference between the first phase distribution and the second phase distribution;
calibrating a set of phase tilt data utilizing the determined second phase tilt and the magnitude of the first and second intentional overlay; and
determining a test overlay value associated with the first overlay target and the second overlay target by comparing the first phase tilt to the calibrated set of phase tilt data.
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Accused Products
Abstract
The present invention may include measuring a first phase distribution across a pupil plane of a portion of illumination reflected from a first overlay target of a semiconductor wafer, wherein the first overlay target is fabricated to have a first intentional overlay, measuring a second phase distribution across the pupil plane of a portion of illumination reflected from a second overlay target, wherein the second overlay target is fabricated to have a second intentional overlay in a direction opposite to and having the same magnitude as the first intentional overlay, determining a first phase tilt associated with a sum of the first and second phase distributions, determining a second phase tilt associated with a difference between the first and second phase distributions, calibrating a set of phase tilt data, and determining a test overlay value associated with the first and second overlay target.
10 Citations
23 Claims
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1. A method for measuring overlay utilizing pupil phase information, comprising:
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measuring a first phase distribution across a pupil plane of a portion of illumination reflected from a first overlay target of a semiconductor wafer, wherein the first overlay target is fabricated to have a first intentional overlay; measuring a second phase distribution across the pupil plane of a portion of illumination reflected from a second overlay target of the semiconductor wafer, wherein the second overlay target is fabricated to have a second intentional overlay, wherein the second intentional overlay is along a direction opposite to the first intentional overlay, wherein the first intentional overlay and the second intentional overlay have substantially the same magnitude; determining a first phase tilt associated with a sum of the first phase distribution and the second phase distribution; determining a second phase tilt associated with a difference between the first phase distribution and the second phase distribution; calibrating a set of phase tilt data utilizing the determined second phase tilt and the magnitude of the first and second intentional overlay; and determining a test overlay value associated with the first overlay target and the second overlay target by comparing the first phase tilt to the calibrated set of phase tilt data. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for measuring overlay utilizing pupil phase information, comprising:
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measuring a first phase distribution across a pupil plane of a portion of illumination reflected from a first overlay target of a semiconductor wafer, wherein the first overlay target is fabricated to have a first intentional overlay;
having a selected magnitude along a selected direction;measuring a second phase distribution across the pupil plane of a portion of illumination reflected from a second overlay target of the semiconductor wafer, wherein the second overlay target is fabricated to have a second intentional overlay, wherein the second intentional overlay is along a direction opposite to the first intentional overlay, wherein the first intentional overlay and the second intentional overlay have substantially the same magnitude; measuring a third phase distribution across the pupil plane of a portion of illumination reflected from a third overlay target of the semiconductor wafer, wherein the third overlay target is fabricated to have zero intentional overlay; determining a first phase tilt associated with a sum of the first phase distribution and the second phase distribution; determining at least one of a second phase tilt or a third phase tilt, wherein the second phase tilt is associated with a difference between the first phase distribution and the third phase distribution and the third phase tilt is associated with a difference between the third phase distribution and the second phase distribution; calibrating a set of phase tilt data utilizing at least one of the second phase tilt or the third phase tilt and the magnitude of the first intentional overlay and the second intentional overlay; and determining one or more test overlay values associated with the first overlay target, the second overlay target, and the third overlay target by comparing the first phase tilt to the calibrated set of phase tilt data. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A system for measuring overlay utilizing pupil phase information, comprising:
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a phase based metrology system configured to; measure a first phase distribution across a pupil plane of a portion of illumination reflected from a first overlay target of a semiconductor wafer, wherein the first overlay target is fabricated to have a first intentional overlay; and measure a second phase distribution across the pupil plane of a portion of illumination reflected from a second overlay target of the semiconductor wafer, wherein the second overlay target is fabricated to have a second intentional overlay, wherein the second intentional overlay is along a direction opposite to the first intentional overlay, wherein the first intentional overlay and the second intentional overlay have substantially the same magnitude; and one or more computer systems configured to; determine a first phase tilt associated with a sum of the first phase distribution and the second phase distribution; determine a second phase tilt associated with a difference between the first phase distribution and the second phase distribution; and calibrate a set of phase tilt data utilizing the determined second phase tilt; and determine a test overlay value associated with the first overlay target and the second overlay target utilizing by comparing the first phase tilt to the calibrated set of phase tilt data. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification