Abstract: A method of determining a parameter of a patterning process, the method including: obtaining a detected representation of radiation redirected by a structure having geometric symmetry at a nominal physical configuration, wherein the detected representation of the radiation was obtained by illuminating a substrate with a radiation beam such that a beam spot on the substrate was filled with the structure; and determining, by a hardware computer system, a value of the patterning process parameter based on optical characteristic values from an asymmetric optical characteristic distribution portion of the detected radiation representation with higher weight than another portion of the detected radiation representation, the asymmetric optical characteristic distribution arising from a different physical configuration of the structure than the nominal physical configuration.

Abstract: A method to calculate a model of a metrology process including receiving a multitude of SEM measurements of a parameter of a semiconductor process, receiving a multitude of optical measurements of the parameter of a semiconductor process, determining a model of a metrology process wherein the optical measurements of the parameter of semiconductor process are mapped to the SEM measurements of the parameter of the semiconductor process using a regression algorithm.

Abstract: A method including: obtaining a detected representation of radiation redirected by each of a plurality of structures from a substrate additionally having a device pattern thereon, wherein each structure has an intentional different physical configuration of the respective structure than the respective nominal physical configuration of the respective structure, wherein each structure has geometric symmetry at the respective nominal physical configuration, wherein the intentional different physical configuration of the structure causes an asymmetric optical characteristic distribution and wherein a patterning process parameter measures change in the physical configuration; and determining a value, based on the detected representations and based on the intentional different physical configurations, to setup, monitor or correct a measurement recipe for determining the patterning process parameter.

Abstract: Measurements are obtained from locations across a substrate before or after performing a lithographic process step. Examples of such measurements include alignment measurements made prior to applying a pattern to the substrate, and measurements of a performance parameter such as overlay, after a pattern has been applied. A set of measurement locations is selected from among all possible measurement locations. At least a subset of the selected measurement locations are selected dynamically, in response to measurements obtained using a preliminary selection of measurement locations. Preliminary measurements of height can be used to select measurement locations for alignment. In another aspect, outlier measurements are detected based on supplementary data such as height measurements or historic data.

Abstract: A method of determining overlay of a patterning process, the method including: obtaining a detected representation of radiation redirected by one or more physical instances of a unit cell, wherein the unit cell has geometric symmetry at a nominal value of overlay and wherein the detected representation of the radiation was obtained by illuminating a substrate with a radiation beam such that a beam spot on the substrate was filled with the one or more physical instances of the unit cell; and determining, from optical characteristic values from the detected radiation representation, a value of a first overlay for the unit cell separately from a second overlay for the unit cell that is also obtainable from the same optical characteristic values, wherein the first overlay is in a different direction than the second overlay or between a different combination of parts of the unit cell than the second overlay.

Abstract: A method of determining a parameter of a patterning process, the method including: obtaining a detected representation of radiation redirected by a structure having geometric symmetry at a nominal physical configuration, wherein the detected representation of the radiation was obtained by illuminating a substrate with a radiation beam such that a beam spot on the substrate was filled with the structure; and determining, by a hardware computer system, a value of the patterning process parameter based on optical characteristic values from an asymmetric optical characteristic distribution portion of the detected radiation representation with higher weight than another portion of the detected radiation representation, the asymmetric optical characteristic distribution arising from a different physical configuration of the structure than the nominal physical configuration.

Abstract: A method of measuring overlay uses a plurality of asymmetry measurements from locations (LOI) on a pair of sub-targets (1032, 1034) formed on a substrate (W). For each sub-target, the plurality of asymmetry measurements are fitted to at least one expected relationship (1502, 1504) between asymmetry and overlay, based on a known bias variation deigned into the sub-targets. Continuous bias variation in one example is provided by varying the pitch of top and bottom gratings (P1/P2). Bias variations between the sub-targets of the pair are equal and opposite (P2/P1). Overlay (OV) is calculated based on a relative shifht (xs) between the fitted relationships for the two sub-targets. The step of fitting asymmetry measurements to at least one expected relationship includes wholly or partially discounting measurements (1506, 1508, 1510) that deviate from the expected relationship and/or fall outside a particular segment of the fitted relationship.

Abstract: A metrology target includes: a first structure arranged to be created by a first patterning process; and a second structure arranged to be created by a second patterning process, wherein the first structure and/or second structure is not used to create a functional aspect of a device pattern, and wherein the first and second structures together form one or more instances of a unit cell, the unit cell having geometric symmetry at a nominal physical configuration and wherein the unit cell has a feature that causes, at a different physical configuration than the nominal physical configuration due to a relative shift in pattern placement in the first patterning process, the second patterning process and/or another patterning process, an asymmetry in the unit cell.

Abstract: A lithographic apparatus prints a focus metrology pattern (T) on a substrate, the printed pattern including at least a first array of features (800). Features at any location within the array define a pattern that repeats at in at least a first direction of periodicity (X), while geometric parameters of the repeating pattern (w1, w3) vary over the array. A focus measurement is derived from measurements of the array at a selected subset of locations (ROI). As a result, the geometric parameters upon which the measurement of focus performance is based can be optimized by selection of locations within the array. The need to optimize geometric parameters of a target design on a reticle (MA) is reduced or eliminated. The measured property may be asymmetry, for example, and/or diffraction efficiency. The measured property for all locations may be captured by dark-field imaging, and a subset of locations selected after capture.

Abstract: Methods of controlling a patterning process are disclosed. In one arrangement, tilt data resulting from a measurement of tilt in an etching path through a target layer of a structure on a substrate is obtained. The tilt represents a deviation in a direction of the etching path from a perpendicular to the plane of the target layer. The tilt data is used to control a patterning process used to form a pattern in a further layer.

Abstract: A method of configuring a parameter determination process, the method including: obtaining a mathematical model of a structure, the mathematical model configured to predict an optical response when illuminating the structure with a radiation beam and the structure having geometric symmetry at a nominal physical configuration; using, by a hardware computer system, the mathematical model to simulate a perturbation in the physical configuration of the structure of a certain amount to determine a corresponding change of the optical response in each of a plurality of pixels to obtain a plurality of pixel sensitivities; and based on the pixel sensitivities, determining a plurality of weights for combination with measured pixel optical characteristic values of the structure on a substrate to yield a value of a parameter associated with change in the physical configuration, each weight corresponding to a pixel.

Abstract: A method of determining overlay of a patterning process, the method including: obtaining a detected representation of radiation redirected by one or more physical instances of a unit cell, wherein the unit cell has geometric symmetry at a nominal value of overlay and wherein the detected representation of the radiation was obtained by illuminating a substrate with a radiation beam such that a beam spot on the substrate was filled with the one or more physical instances of the unit cell; and determining, from optical characteristic values from the detected radiation representation, a value of a first overlay for the unit cell separately from a second overlay for the unit cell that is also obtainable from the same optical characteristic values, wherein the first overlay is in a different direction than the second overlay or between a different combination of parts of the unit cell than the second overlay.

Abstract: A lithographic apparatus prints a focus metrology pattern (T) on a substrate, the printed pattern including at least a first array of features (800). Features at any location within the array define a pattern that repeats at in at least a first direction of periodicity (X), while geometric parameters of the repeating pattern (w1, w3) vary over the array. A focus measurement is derived from measurements of the array at a selected subset of locations (ROI). As a result, the geometric parameters upon which the measurement of focus performance is based can be optimized by selection of locations within the array. The need to optimize geometric parameters of a target design on a reticle (MA) is reduced or eliminated. The measured property may be asymmetry, for example, and/or diffraction efficiency. The measured property for all locations may be captured by dark-field imaging, and a subset of locations selected after capture.

Abstract: A method of measuring overlay uses a plurality of asymmetry measurements from locations (LOI) on a pair of sub-targets (1032, 1034) formed on a substrate (W). For each sub-target, the plurality of asymmetry measurements are fitted to at least one expected relationship (1502, 1504) between asymmetry and overlay, based on a known bias variation deigned into the sub-targets. Continuous bias variation in one example is provided by varying the pitch of top and bottom gratings (P1/P2). Bias variations between the sub-targets of the pair are equal and opposite (P2/P1). Overlay (OV) is calculated based on a relative shift (xs) between the fitted relationships for the two sub-targets. The step of fitting asymmetry measurements to at least one expected relationship includes wholly or partially discounting measurements (1506, 1508, 1510) that deviate from the expected relationship and/or fall outside a particular segment of the fitted relationship.

Abstract: A method including: obtaining a detected representation of radiation redirected by each of a plurality of structures from a substrate additionally having a device pattern thereon, wherein each structure has an intentional different physical configuration of the respective structure than the respective nominal physical configuration of the respective structure, wherein each structure has geometric symmetry at the respective nominal physical configuration, wherein the intentional different physical configuration of the structure causes an asymmetric optical characteristic distribution and wherein a patterning process parameter measures change in the physical configuration; and determining a value, based on the detected representations and based on the intentional different physical configurations, to setup, monitor or correct a measurement recipe for determining the patterning process parameter.

Abstract: Measurements are obtained from locations across a substrate before or after performing a lithographic process step. Examples of such measurements include alignment measurements made prior to applying a pattern to the substrate, and measurements of a performance parameter such as overlay, after a pattern has been applied. A set of measurement locations is selected from among all possible measurement locations. At least a subset of the selected measurement locations are selected dynamically, in response to measurements obtained using a preliminary selection of measurement locations. Preliminary measurements of height can be used to select measurement locations for alignment. In another aspect, outlier measurements are detected based on supplementary data such as height measurements or historic data.

Abstract: A method of determining a parameter of a pattern transfer process and device manufacturing methods are disclosed. In one arrangement, a method includes obtaining a detected representation of radiation redirected by a structure. The structure is a structure formed by applying a pattern processing to a pattern transferred to an earlier formed structure by a pattern transfer process. The pattern processing is such as to remove one or more selected regions in a horizontal plane of the earlier formed structure to form a pattern in the horizontal plane. The pattern is defined by a unit cell that is mirror symmetric with respect to an axis of mirror symmetry. An asymmetry in the detected representation is determined. The determined asymmetry in the detected representation is used to determine a parameter of the pattern transfer process.

Abstract: A method, including: measuring a first plurality of instances of a metrology target on a substrate processed using a patterning process to determine values of at least one parameter of the patterning process using a first metrology recipe for applying radiation to, and detecting radiation from, instances of the metrology target; and measuring a second different plurality of instances of the metrology target on the same substrate to determine values of the at least one parameter of the patterning process using a second metrology recipe for applying radiation to, and detecting radiation from, instances of the metrology target, wherein the second metrology recipe differs from the first metrology recipe in at least one characteristic of the applying radiation to, and detecting radiation from, instances of the metrology target.

Abstract: A method defines one or more monitoring target profiles, collects and stores initial calibration data of the metrology apparatus, compiling a library of spectra that would be observed from inspection of the monitoring target profiles using the metrology apparatus calibrated according to the initial calibration data. Some operations can be performed periodically, e.g., on a daily basis: obtaining current calibration data from the apparatus, modeling the effect of the current calibration data on the metrology apparatus operation, and using the result of the modeling and the contents of the library to determine any differences between one or more values of the initial calibration data and the current calibration data, and how these changes will be translated into changes in the measurement output for a given number of stacks and geometries.

Abstract: A method defines one or more monitoring target profiles, collects and stores initial calibration data of the metrology apparatus, compiling a library of spectra that would be observed from inspection of the monitoring target profiles using the metrology apparatus calibrated according to the initial calibration data. Some operations can be performed periodically, e.g., on a daily basis: obtaining current calibration data from the apparatus, modeling the effect of the current calibration data on the metrology apparatus operation, and using the result of the modeling and the contents of the library to determine any differences between one or more values of the initial calibration data and the current calibration data, and how these changes will be translated into changes in the measurement output for a given number of stacks and geometries.