Abstract: An alignment method includes directing an illumination beam with a first polarization state to form a diffracted beam with a second polarization state from an alignment target, and passing the diffracted beam through a polarization analyzer. The alignment method further includes measuring a polarization state of the diffracted beam and determining a location of the alignment target from the measured polarization state relative to its initial polarization state. The alignment target includes a plurality of diffraction gratings with a single pitch and two or more duty cycles, wherein the pitch is smaller than a wavelength of the illumination beam, and the location of the alignment target corresponds to the duty cycle of the diffraction grating.

Abstract: An apparatus for and method of sensing alignment marks in which a self-referencing interferometer based sensor outputs standing images of the alignment marks and camera device is used to capture the images as output by the sensor and a detector is used to obtain phase information about the alignment marks from the images as output by the sensor.

Abstract: A measurement apparatus, including: a tapered optical fiber, the tapered optical fiber having an input to receive radiation and having an output to provide spectrally broadened output radiation toward a measurement target, the tapered optical fiber configured to spectrally broaden the radiation received at the input; and a detector system configured to receive a redirected portion of the output radiation from the measurement target.

Abstract: A method for generating an alignment signal that includes detecting local dimensional distortions of an alignment mark and generating the alignment signal based on the alignment mark. The alignment signal is weighted based on the local dimensional distortions of the alignment mark. Detecting the local dimensional distortions can include irradiating the alignment mark with radiation, the alignment mark including a geometric feature, and detecting one or more phase and/or amplitude shifts in reflected radiation from the geometric feature. The one or more phase and/or amplitude shifts correspond to the local dimensional distortions of the geometric feature. A parameter of the radiation, an alignment inspection location within the geometric feature, an alignment inspection location on a layer of a structure, and/or a radiation beam trajectory across the geometric feature may be determined based on the one or more detected phase and/or amplitude shifts.

Abstract: A method of applying a measurement correction includes determining an orthogonal subspace used to characterize a first principal component of the measurement and a second principal component of the measurement, and rotating the orthogonal subspace by a first angle such that the first principle component rotates to become a first factor vector and the second principle component rotates to become a second factor vector. An asymmetry vector is generated by rotating the second factor vector by a second angle, where the asymmetry vector and the first factor vector define a non-orthogonal subspace. An asymmetry contribution is determined in the measurement based on the projection of the measurement onto the first factor vector in the non-orthogonal subspace. The method also includes subtracting the asymmetry contribution from the measurement.

Abstract: A method of applying a measurement correction includes determining an orthogonal subspace used to characterize the measurement as a plot of data. A first axis of the orthogonal subspace corresponds to constructive interference output from an interferometer of the metrology system plus a first error variable and a second axis of the orthogonal subspace corresponds to destructive interference output from the interferometer of the metrology system plus a second error variable. The method also includes determining a slope of the plot of data and determining a fitted line to the plot of data in the orthogonal subspace based on the slope.

Abstract: An alignment method includes directing an illumination beam with a first polarization state to form a diffracted beam with a second polarization state from an alignment target, and passing the diffracted beam through a polarization analyzer. The alignment method further includes measuring a polarization state of the diffracted beam and determining a location of the alignment target from the measured polarization state relative to its initial polarization state. The alignment target includes a plurality of diffraction gratings with a single pitch and two or more duty cycles, wherein the pitch is smaller than a wavelength of the illumination beam, and the location of the alignment target corresponds to the duty cycle of the diffraction grating.

Abstract: A method of applying a measurement correction includes determining an orthogonal subspace used to characterize the measurement as a plot of data. A first axis of the orthogonal subspace corresponds to constructive interference output from an interferometer of the metrology system plus a first error variable and a second axis of the orthogonal subspace corresponds to destructive interference output from the interferometer of the metrology system plus a second error variable. The method also includes determining a slope of the plot of data and determining a fitted line to the plot of data in the orthogonal subspace based on the slope.

Abstract: A method of applying a measurement correction includes determining an orthogonal subspace used to characterize a first principal component of the measurement and a second principal component of the measurement, and rotating the orthogonal subspace by a first angle such that the first principle component rotates to become a first factor vector and the second principle component rotates to become a second factor vector. An asymmetry vector is generated by rotating the second factor vector by a second angle, where the asymmetry vector and the first factor vector define a non-orthogonal subspace. An asymmetry contribution is determined in the measurement based on the projection of the measurement onto the first factor vector in the non-orthogonal subspace. The method also includes subtracting the asymmetry contribution from the measurement.

Abstract: An alignment sensor apparatus includes an illumination system, a first optical system, a second optical system, a detector system, and a processor. The illumination system is configured to transmit an illumination beam along an illumination path. The first optical system is configured to transmit the illumination beam toward a diffraction target on a substrate. The second optical system includes a first polarizing optic configured to separate and transmit an irradiance distribution. The detector system is configured to measure a center of gravity of the diffraction target based on the irradiance distribution outputted from a first polarization branch and a second polarization branch. The processor is configured to measure a shift in the center of gravity of the diffraction target caused by an asymmetry variation in the diffraction target and determine a sensor response function of the alignment sensor apparatus based on the center of gravity shift.

Abstract: An alignment mark for determining a two-dimensional alignment position of a substrate is discussed. The alignment mark includes an array of patterns. The array of patterns includes a first set of patterns and a second set of patterns arranged. The first set of patterns is arranged in a first sequence along a first direction. The second set of patterns is arranged in a second sequence along the first direction. The second sequence is different from the first sequence. Each pattern of the array of patterns is different from other patterns of the array of patterns that are adjacent to the each pattern.

Abstract: An alignment sensor apparatus includes an illumination system, a first optical system, a second optical system, a detector system, and a processor. The illumination system is configured to transmit an illumination beam along an illumination path. The first optical system is configured to transmit the illumination beam toward a diffraction target on a substrate. The second optical system includes a first polarizing optic configured to separate and transmit an irradiance distribution. The detector system is configured to measure a center of gravity of the diffraction target based on the irradiance distribution outputted from a first polarization branch and a second polarization branch. The processor is configured to measure a shift in the center of gravity of the diffraction target caused by an asymmetry variation in the diffraction target and determine a sensor response function of the alignment sensor apparatus based on the center of gravity shift.

Abstract: A method of applying a measurement correction includes calculating a first correction value based on a first coefficient and the measurement; calculating a second correction value based on a second coefficient, greater than the first coefficient, and the measurement; and calculating a third correction value based on a third coefficient, greater than the second coefficient, and the measurement. The method also includes applying the third correction value to the measurement if a difference between the first correction value and the third correction value is above a first threshold value; applying the second correction value to the measurement if a difference between the first correction value and the second correction value is above a second threshold value; and applying the first correction value to the measurement if the difference between the first correction value and the second correction value is below or equal to the second threshold value.

Abstract: A measurement apparatus, including: a tapered optical fiber, the tapered optical fiber having an input to receive radiation and having an output to provide spectrally broadened output radiation toward a measurement target, the tapered optical fiber configured to spectrally broaden the radiation received at the input; and a detector system configured to receive a redirected portion of the output radiation from the measurement target.

Abstract: A measurement apparatus, including: a tapered optical fiber, the tapered optical fiber having an input to receive radiation and having an output to provide spectrally broadened output radiation toward a measurement target, the tapered optical fiber configured to spectrally broaden the radiation received at the input; and a detector system configured to receive a redirected portion of the output radiation from the measurement target.

Abstract: An alignment mark for determining a two-dimensional alignment position of a substrate is discussed. The alignment mark includes an array of patterns. The array of patterns includes a first set of patterns and a second set of patterns arranged. The first set of patterns is arranged in a first sequence along a first direction. The second set of patterns is arranged in a second sequence along the first direction. The second sequence is different from the first sequence. Each pattern of the array of patterns is different from other patterns of the array of patterns that are adjacent to the each pattern.

Abstract: An alignment system obtains the characteristics of the light coming back from a wafer stack. A beam analyzer measures changes in wavelength, polarization, and beam profile. This measured information allows for in-line process variation corrections. The correction provides optical monitoring of individual mark stack variations, and in turn provides information to reduce individual mark process variation-induced accuracy error.

Abstract: A method, including printing an apparatus mark onto a structure while the structure is at least partly within a lithographic apparatus. The structure may be part of, or is located on, a substrate table, but is separate from a substrate to be held by the apparatus. The method further includes measuring the apparatus mark using a sensor system within the apparatus.

Abstract: An alignment system obtains the characteristics of the light coming back from a wafer stack. A beam analyzer measures changes in wavelength, polarization, and beam profile. This measured information allows for in-line process variation corrections. The correction provides optical monitoring of individual mark stack variations, and in turn provides information to reduce individual mark process variation-induced accuracy error.

Abstract: A method, including printing an apparatus mark onto a structure while the structure is at least partly within a lithographic apparatus. The structure may be part of, or is located on, a substrate table, but is separate from a substrate to be held by the apparatus. The method further includes measuring the apparatus mark using a sensor system within the apparatus.