Evaluating sidewall coverage in a semiconductor wafer
First Claim
1. A method of evaluating a feature in a semiconductor wafer, the method comprising:
- illuminating the wafer with a beam of electromagnetic radiation having a majority of energy polarized in a direction other than parallel to a longitudinal direction of the feature; and
measuring intensity of a portion of the beam reflected by the wafer.
2 Assignments
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Accused Products
Abstract
A sidewall or other feature in a semiconductor wafer is evaluated by illuminating the wafer with at least one beam of electromagnetic radiation, and measuring intensity of a portion of the beam reflected by the wafer. Change in reflectance between measurements provides a measure of a property of the feature. The change may be either a decrease in reflectance or an increase in reflectance, depending on the embodiment. A single beam may be used if it is polarized in a direction substantially perpendicular to a longitudinal direction of the sidewall. A portion of the energy of the beam is absorbed by the sidewall, thereby to cause a decrease in reflectance when compared to reflectance by a flat region. Alternatively, two beams may be used, of which a first beam applies heat to the feature itself or to a region adjacent to the feature, and a second beam is used to measure an increase in reflectance caused by an elevation in temperature due to heat transfer through the feature. The elevation in temperature that is measured can be either of the feature itself, or of a region adjacent to the feature.
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Citations
37 Claims
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1. A method of evaluating a feature in a semiconductor wafer, the method comprising:
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illuminating the wafer with a beam of electromagnetic radiation having a majority of energy polarized in a direction other than parallel to a longitudinal direction of the feature; and
measuring intensity of a portion of the beam reflected by the wafer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17, 19, 20, 21, 22, 24, 25, 26, 27, 28, 30, 31, 32, 33, 34, 35, 37)
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16. A method of evaluating wafers during fabrication, the method comprising:
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forming a feature of conductive material in a wafer by using at least one process parameter;
illuminating the wafer with a beam of electromagnetic radiation having a majority of energy polarized in a direction other than parallel to a longitudinal direction of the feature; and
repeatedly measuring intensity of a portion of the beam reflected by the wafer at a plurality of locations transverse to the longitudinal direction; and
changing the process parameter depending on measurements obtained from the act of repeatedly measuring.
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18. A method of evaluating a feature in a semiconductor wafer, the method comprising:
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illuminating the wafer with two beams, each beam forming a spot; and
performing a measurement with the first spot and the second spots located on opposite sides of the feature.
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23. A method of evaluating a feature in a semiconductor wafer, the method comprising:
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illuminating the wafer with two beams, a first beam having a first intensity larger than a second intensity of a second beam, the first beam having a majority of energy polarized in a direction other than parallel to a longitudinal direction of the feature; and
measuring intensity of a portion of the second beam reflected by the wafer
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29. An apparatus for evaluating a feature in a wafer, the apparatus comprising:
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a laser source for generating a beam polarized in a direction other than parallel to a longitudinal direction of the feature; and
a photosensitive element located in a path of radiation of electromagnetic energy from the wafer.
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36. An apparatus comprising:
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means for illuminating a semiconductor wafer with a beam of electromagnetic radiation having a majority of energy polarized in a direction other than parallel to a longitudinal direction of the feature; and
means for measuring intensity of a portion of the beam reflected by the wafer, the means for measuring being coupled to the means for illuminating.
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Specification