Method of Assessing a Model of a Substrate, an Inspection Apparatus and a Lithographic Apparatus
First Claim
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1. A method comprising:
- taking a first scatterometry measurement of a substrate using radiation having known characteristics, the radiation having a first characteristic value;
determining a value of a characteristic of a feature of the substrate or a first residual using the first scatterometry measurement;
taking a second scatterometry measurement using the radiation having a second characteristic value;
determining a second value of the characteristic of the feature or a second residual using the second scatterometry measurement; and
comparing the first value and the second value of the characteristic of the feature or the first residual and the second residual to determine an accuracy of a model.
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Abstract
A method of assessing a model of a substrate is presented. A scatterometry measurement is taken using radiation at a first wavelength. The wavelength of the radiation is then changed and a further scatterometry measurement taken. If the scatterometry measurements are consistent across a range of wavelengths then the model is sufficiently accurate. However, if the scatterometry measurements change as the wavelength changes then the model of the substrate is not sufficiently accurate.
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Citations
21 Claims
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1. A method comprising:
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taking a first scatterometry measurement of a substrate using radiation having known characteristics, the radiation having a first characteristic value; determining a value of a characteristic of a feature of the substrate or a first residual using the first scatterometry measurement; taking a second scatterometry measurement using the radiation having a second characteristic value; determining a second value of the characteristic of the feature or a second residual using the second scatterometry measurement; and comparing the first value and the second value of the characteristic of the feature or the first residual and the second residual to determine an accuracy of a model. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. (canceled)
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11. An inspection apparatus comprising:
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a radiation projector configured to project radiation onto a substrate, the radiation having a characteristic with a plurality of values; a high numerical aperture lens; and a detector configured to detect the radiation reflected from a surface of the substrate, wherein the detector is configured to separate the detected radiation into a plurality of sub-divisions, the radiation of each sub-division having a different value for the characteristic. - View Dependent Claims (12, 13)
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14. (canceled)
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15. (canceled)
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16. A lithographic apparatus comprising:
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an illumination system arranged to illuminate a pattern; a projection system arranged to project an image of the pattern on to a substrate; and an inspection apparatus configured to measure a target on the substrate, the inspection apparatus comprising, a radiation projector configured to project radiation onto the substrate, the radiation having a characteristic with a plurality of valuesl a high numerical aperture lensl and a detector configured to detect the radiation reflected from a surface of the substratel wherein the detector is configured to separate the detected radiation into a plurality of sub-divisions, the radiation of each sub-division having a different value for the characteristic. - View Dependent Claims (17, 18)
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19. (canceled)
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20. (canceled)
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21. (canceled)
Specification