Method and apparatus for accurate calibration of a reflectometer by using a relative reflectance measurement
First Claim
1. A method of calibrating a reflectometer, comprising:
- providing a first calibration sample and a second calibration sample, wherein the reflectance properties of the first calibration sample and the second calibration sample are different;
collecting a first set of data from the first calibration sample;
collecting a second set of data from the second calibration sample; and
utilizing a ratio of at least a portion of the first set of data and at least a portion of the second set of data to determine a property of at least one of the first and second calibration samples so that reflectance data from an unknown sample may be calibrated.
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Accused Products
Abstract
A reflectometer calibration technique is provided that may include the use of two calibration samples in the calibration process. Further, the technique allows for calibration even in the presence of variations between the actual and assumed properties of at least one or more of the calibration samples. In addition, the technique utilizes a ratio of the measurements from the first and second calibration samples to determine the actual properties of at least one of the calibration samples. The ratio may be a ratio of the intensity reflected from the first and second calibration samples. The samples may exhibit relatively different reflective properties at the desired wavelengths. In such a technique the reflectance data of each sample may then be considered relatively decoupled from the other and actual properties of one or more of the calibration samples may be calculated. The determined actual properties may then be utilized to assist calibration of the reflectometer.
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Citations
41 Claims
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1. A method of calibrating a reflectometer, comprising:
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providing a first calibration sample and a second calibration sample, wherein the reflectance properties of the first calibration sample and the second calibration sample are different;
collecting a first set of data from the first calibration sample;
collecting a second set of data from the second calibration sample; and
utilizing a ratio of at least a portion of the first set of data and at least a portion of the second set of data to determine a property of at least one of the first and second calibration samples so that reflectance data from an unknown sample may be calibrated. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 37, 38, 40)
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16. A method of calibrating a reflectometer which operates at wavelengths that include at least some wavelengths below deep ultra-violet (DUV) wavelengths, comprising:
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providing a first calibration sample and a second calibration sample, wherein the reflectance properties of the first calibration sample and the second calibration sample are different;
collecting a first set of data from a first calibration sample, the first set of data including at least some intensity data collected for wavelengths below DUV wavelengths;
collecting a second set of data from the second calibration sample, the second set of data including at least some intensity data collected for wavelengths below DUV wavelengths; and
utilizing a ratio based on the first set of data and the second set of data to determine a reflectance of at least one of the first calibration sample and the second calibration sample to assist in calibrating the reflectometer at wavelengths that include at least some wavelengths below DUV wavelengths. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 39, 41)
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30. A method of analyzing reflectometer data, comprising:
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providing a first reflectometer sample and at least a second reflectometer sample, wherein the optical response properties of the first reflectometer sample and the second reflectometer sample are different;
collecting a first set of optical response data from the first reflectometer sample;
collecting a second set of optical response data from the second reflectometer sample; and
determining at least one property of at least one of the first and second reflectometer samples by utilizing the first set and second set of optical response data in a manner independent of an incident reflectometer intensity that is utilized when collecting the first and second set of optical response data. - View Dependent Claims (31, 32, 33, 34, 35, 36)
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Specification