Transverse differential interferometric confocal microscopy
First Claim
1. A differential interferometric confocal microscope for measuring an object, said microscope comprising:
- a source-side pinhole array;
a detector-side pinhole array; and
an interferometer that images the array of pinholes of the source-side pinhole array onto a first array of spots on or in the object and onto a second array of spots on or in the object, wherein the first and second arrays of spots are displaced from each other so each pinhole of the source-side pinhole array is imaged onto two corresponding different locations that are displaced from each other, said interferometer also imaging both the first and second array of spots onto the detector-side pinhole array so that each spot of the first array of spots and its corresponding spot of the second array of spots is imaged onto a corresponding pinhole of the detector-side pinhole array.
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Accused Products
Abstract
An array of conjugated quadratures of fields is measured interferometrically by a confocal interferometer and detector system wherein each conjugated quadratures comprises a difference of conjugated quadratures of fields of beams scattered/reflected or transmitted by a pair of spots in or on a substrate. The array of conjugated quadratures is measured jointly, i.e., simultaneously, and the components of each conjugated quadratures may be measured jointly. Each pair of spots generally has a relative displacement on the order of the three or more times the size of the spots in a direction nominally tangent to the surface of the substrate. The relative phases of the beams subsequently scattered/reflected or transmitted by the pair of spots on/in a substrate may be adjusted as a set by control of a single system parameter so that the conjugated quadratures of the array of conjugated quadratures are nominally zero, i.e., information may be obtained about the substrate with the interferometer and detector system operating in a dark field mode. Operation in a dark field mode leads to both reduced systematic and statistical errors in the information and increased throughput. The information may include the transverse derivative of a profile of one or more surfaces of a substrate; one-dimensional, two-dimensional, and three-dimensional transverse differential images of a substrate; critical dimensions of features or artifacts on or in a substrate, and the size and location of sub-wavelength defects in or on a substrate.
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Citations
28 Claims
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1. A differential interferometric confocal microscope for measuring an object, said microscope comprising:
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a source-side pinhole array;
a detector-side pinhole array; and
an interferometer that images the array of pinholes of the source-side pinhole array onto a first array of spots on or in the object and onto a second array of spots on or in the object, wherein the first and second arrays of spots are displaced from each other so each pinhole of the source-side pinhole array is imaged onto two corresponding different locations that are displaced from each other, said interferometer also imaging both the first and second array of spots onto the detector-side pinhole array so that each spot of the first array of spots and its corresponding spot of the second array of spots is imaged onto a corresponding pinhole of the detector-side pinhole array.
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2. A differential interferometric confocal microscope for measuring an object, said microscope comprising:
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a source-side pinhole array;
a detector-side pinhole array; and
an interferometer that images each pinhole of the source-side pinhole array onto a corresponding pair of two different spots on or in the object to thereby generate a first image of the source-side pinhole array and a second image of the source-side pinhole array that is displaced from the first image of the source-side pinhole array and that images both spots of each corresponding pair of spots onto a corresponding pinhole of the detector-side pinhole array. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A differential interferometric confocal microscope for measuring an object, said microscope comprising:
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a source for producing an input optical beam;
a pinhole beam-splitter including a pinhole arranged to receive the optical input beam and generate a first measurement beam, a second measurement beam, and a reference beam therefrom; and
an interferometer that focuses the first and second measurement beams onto a first spot on or in the object and onto a second spot on or in the object, said second spot displaced from said first spot, said interferometer further imaging both the first and second spots onto the pinhole of the pinhole beam-splitter so as to combine the reference beam and optical signals coming from both the first and second spots to produce an interference beam. - View Dependent Claims (27)
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28. A differential interferometric confocal microscope for measuring an object, said microscope comprising:
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a source for producing an input optical beam;
a plate defining a pinhole and arranged to receive the input optical beam;
an interferometer that images the pinhole onto a corresponding pair of two different spots on or in the object and that images the two spots of each corresponding pair of spots back onto a the pinhole to generate an output beam; and
a detector arranged to receive the output beam.
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Specification