Abstract: A method for determining a measurement setting for measuring a parameter of interest from a target structure on a substrate. The method includes: obtaining first position difference data describing a difference between a position of a first representative target structure position and a position of one or more first features relating to product structure; obtaining optical metrology data relating to optical measurements of the target structure and further relating to a plurality of different measurement settings; and determining the measurement setting from the first position difference data and the optical metrology data such that a measured feature position value obtained from an optical measurement of the target structure using the determined measurement setting is better correlated to a position of the one or more first features.

Abstract: A method for a metrology process, the method includes obtaining first measurement data relating to a first set of measurement conditions and determining a first measurement recipe based on the first measurement data. At least one performance indicator is determined from one or more components of the first measurement data obtained from a component analysis or statistical decomposition. Alternatively, at least one performance indicator is determined from a comparison of one or more first measurement values relating to the first measurement recipe and one or more second measurement values relating to a second measurement recipe, where second measurement recipe is different to the first measurement data and relates a second set of measurement conditions, the second set of measurement conditions being different to the first set of measurement conditions.

Abstract: Disclosed is a method of improving a measurement of a parameter of interest. The method comprises obtaining metrology data comprising a plurality of measured values of the parameter of interest, relating to one or more targets on a substrate, each measured value relating to a different measurement combination of a target of said one or more targets and a measurement condition used to measure that target and asymmetry metric data relating to asymmetry for said one or more targets. A respective relationship is determined for each of said measurement combinations relating a true value for the parameter of interest to the asymmetry metric data, based on an assumption that there is a common true value for the parameter of interest over said measurement combinations. These relationships are used to improve a measurement of the parameter of interest.

Abstract: A method to determine a metrology contribution from statistically independent sources, the method including providing a plurality of contributions from statistically independent sources obtained at a plurality of measurement settings, and determining a metrology contribution from the contributions wherein the metrology contribution is the contribution having least dependence as a function of the measurement settings.

Abstract: An illumination and detection apparatus for a metrology tool, and associated method. The apparatus includes an illumination arrangement operable to produce measurement illumination having a plurality of discrete wavelength bands and having a spectrum having no more than a single peak within each wavelength band. The detection arrangement includes a detection beamsplitter to split scattered radiation into a plurality of channels, each channel corresponding to a different one of the wavelength bands; and at least one detector for separate detection of each channel.

Abstract: A method includes receiving an image formed in a metrology apparatus wherein the image comprises at least the resulting effect of at least two diffraction orders, and processing the image wherein the processing comprises at least a filtering step, for example a Fourier filter. The process of applying a filter may be obtained also by placing an aperture in the detection branch of the metrology apparatus.

Abstract: Methods and systems for determining information about a target structure are disclosed. In one arrangement, a value of an asymmetry indicator for the target structure is obtained. The value of the asymmetry indicator represents an amount of an overlay independent asymmetry in the target structure. An error in an initial overlay measurement performed on the target structure at a previous time is estimated. The estimation is performed using the obtained value of the asymmetry indicator and a relationship between values of the asymmetry indicator and overlay measurement errors caused at least partially by overlay independent asymmetries. An overlay in the target structure is determined using the initial overlay measurement and the estimated error.

Abstract: A metrology method relating to measurement of a structure on a substrate, the structure being subject to one or more asymmetric deviation. The method includes obtaining at least one intensity asymmetry value relating to the one or more asymmetric deviations, wherein the at least one intensity asymmetry value includes a metric related to a difference or imbalance between the respective intensities or amplitudes of at least two diffraction orders of radiation diffracted by the structure; determining at least one phase offset value corresponding to the one or more asymmetric deviations based on the at least one intensity asymmetry value; and determining one or more measurement corrections for the one or more asymmetric deviations from the at least one phase offset value.

Abstract: A method provides the steps of receiving an image from a metrology tool, determining individual units of said image and discriminating the units which provide accurate metrology values. The images are obtained by measuring the metrology target at multiple wavelengths. The discrimination between the units, when these units are pixels in said image, is based on calculating a degree of similarity between said units.

Abstract: A method of inferring a value for at least one local uniformity metric relating to a product structure, the method including: obtaining intensity data including an intensity image relating to at least one diffraction order obtained from a measurement on a target; obtaining at least one intensity distribution from the intensity image; determining, from the at least one intensity distribution, an intensity indicator expressing a variation of either intensity over the at least one diffraction order, or a difference in intensity between two complimentary diffraction orders over the intensity image; and inferring the value for the at least one local uniformity metric from the intensity indicator.

Abstract: Disclosed is a method of measuring a target on a substrate comprising: illuminating a target with measurement radiation comprising at least a first wavelength, collecting the resultant scattered radiation within a collection numerical aperture; and determining a parameter of interest from said scattered radiation. The target comprises a mediator periodic structure and at least a first target periodic structure each in a respective different layer on the substrate, wherein a pitch of at least the mediator periodic structure is below a single diffraction limit defined by the collection numerical aperture and a wavelength of said measurement radiation, such that said scattered radiation comprises double diffracted radiation, said double diffracted radiation comprising radiation having undergone two sequential same-order diffractions of opposite sign.

Abstract: Disclosed is a method of metrology. The method comprises measuring at least one surrounding observable parameter relating to a surrounding signal contribution to a metrology signal which comprises a contribution to said metrology signal which is not attributable to at least one target being measured and determining a correction from said surrounding signal observable parameter. The correction is used to correct first measurement data relating to measurement of one or more targets using measurement radiation forming a measurement spot on one or more of said one or more targets which is larger than one of said targets.

Abstract: A method of inferring a value for at least one local uniformity metric relating to a product structure, the method including: obtaining intensity data including an intensity image relating to at least one diffraction order obtained from a measurement on a target; obtaining at least one intensity distribution from the intensity image; determining, from the at least one intensity distribution, an intensity indicator expressing a variation of either intensity over the at least one diffraction order, or a difference in intensity between two complimentary diffraction orders over the intensity image; and inferring the value for the at least one local uniformity metric from the intensity indicator.

Abstract: Disclosed is a method of improving a measurement of a parameter of interest. The method comprises obtaining metrology data comprising a plurality of measured values of the parameter of interest, relating to one or more targets on a substrate, each measured value relating to a different measurement combination of a target of said one or more targets and a measurement condition used to measure that target and asymmetry metric data relating to asymmetry for said one or more targets. A respective relationship is determined for each of said measurement combinations relating a true value for the parameter of interest to the asymmetry metric data, based on an assumption that there is a common true value for the parameter of interest over said measurement combinations. These relationships are used to improve a measurement of the parameter of interest.

Abstract: Disclosed is method of determining at least one homogeneity metric describing homogeneity of an etched trench on a substrate formed by a lithographic manufacturing process. The method comprises obtaining one or more images of the etched trench, wherein each of said one or more images comprises a spatial representation of one or more parameters of scattered radiation as detected by a detector or camera following scattering and/or diffraction from the etched trench; and measuring homogeneity along the length of the etched trench on said one or more images to determine said at least one homogeneity metric.

Abstract: A method for a metrology process, the method includes obtaining first measurement data relating to a first set of measurement conditions and determining a first measurement recipe based on the first measurement data. At least one performance indicator is determined from one or more components of the first measurement data obtained from a component analysis or statistical decomposition. Alternatively, at least one performance indicator is determined from a comparison of one or more first measurement values relating to the first measurement recipe and one or more second measurement values relating to a second measurement recipe, where second measurement recipe is different to the first measurement data and relates a second set of measurement conditions, the second set of measurement conditions being different to the first set of measurement conditions.

Abstract: A method of inferring a value for at least one local uniformity metric relating to a product structure, the method including: obtaining intensity data including an intensity image relating to at least one diffraction order obtained from a measurement on a target; obtaining at least one intensity distribution from the intensity image; determining, from the at least one intensity distribution, an intensity indicator expressing a variation of either intensity over the at least one diffraction order, or a difference in intensity between two complimentary diffraction orders over the intensity image; and inferring the value for the at least one local uniformity metric from the intensity indicator.

Abstract: A metrology method relating to measurement of a structure on a substrate, the structure being subject to one or more asymmetric deviation. The method includes obtaining at least one intensity asymmetry value relating to the one or more asymmetric deviations, wherein the at least one intensity asymmetry value includes a metric related to a difference or imbalance between the respective intensities or amplitudes of at least two diffraction orders of radiation diffracted by the structure; determining at least one phase offset value corresponding to the one or more asymmetric deviations based on the at least one intensity asymmetry value; and determining one or more measurement corrections for the one or more asymmetric deviations from the at least one phase offset value.

Abstract: Methods and systems for determining information about a target structure are disclosed. In one arrangement, a value of an asymmetry indicator for the target structure is obtained. The value of the asymmetry indicator represents an amount of an overlay independent asymmetry in the target structure. An error in an initial overlay measurement performed on the target structure at a previous time is estimated. The estimation is performed using the obtained value of the asymmetry indicator and a relationship between values of the asymmetry indicator and overlay measurement errors caused at least partially by overlay independent asymmetries. An overlay in the target structure is determined using the initial overlay measurement and the estimated error.

Abstract: An illumination and detection apparatus for a metrology tool, and associated method. The apparatus includes an illumination arrangement operable to produce measurement illumination having a plurality of discrete wavelength bands and having a spectrum having no more than a single peak within each wavelength band. The detection arrangement includes a detection beamsplitter to split scattered radiation into a plurality of channels, each channel corresponding to a different one of the wavelength bands; and at least one detector for separate detection of each channel.