Abstract: A method of determining focus of a lithographic apparatus has the following steps. Using the lithographic process to produce first and second structures on the substrate, the first structure has features which have a profile that has an asymmetry that depends on the focus and an exposure perturbation, such as dose or aberration. The second structure has features which have a profile that is differently sensitive to focus than the first structure and which is differently sensitive to exposure perturbation than the first structure. Scatterometer signals are used to determine a focus value used to produce the first structure. This may be done using the second scatterometer signal, and/or recorded exposure perturbation settings used in the lithographic process, to select a calibration curve for use in determining the focus value using the first scatterometer signal or by using a model with parameters related to the first and second scatterometer signals.

Abstract: Disclosed is a patterning device configured to pattern a beam of radiation according to a desired pattern during a lithographic process. The patterning device comprises first features configured to form a first target on a substrate during the lithographic process and second features configured to form a second target on the substrate during the lithographic process. The second features are taller, in a direction transverse to the plane of the first and second targets, than the first features, such that the first and second targets have a relative best focus offset.

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: illuminating a substrate with a radiation beam such that a beam spot on the substrate is filled with one or more physical instances of a unit cell, the unit cell having geometric symmetry at a nominal value of overlay; detecting primarily zeroth order radiation redirected by the one or more physical instances of the unit cell using a detector; and determining, by a hardware computer system, a non-nominal value of overlay of the unit cell from values of an optical characteristic of the detected radiation.

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 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 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 (LA) prints product features and at least one focus metrology pattern (T) on a substrate. The focus metrology pattern is defined by a reflective reticle and printing is performed using EUV radiation (404) incident at an oblique angle (?). The focus metrology pattern comprises a periodic array of groups of first features (422). A spacing (S1) between adjacent groups of first features is much greater than a dimension (CD) of the first features within each group. Due to the oblique illumination, the printed first features become distorted and/or displaced as a function of focus error. Second features 424 may be provided as a reference against which displacement of the first features may be seen. Measurement of this distortion and/or displacement may be by measuring asymmetry as a property of the printed pattern. Measurement can be done at longer wavelengths, for example in the range 350-800 nm.

Abstract: A method of determining a process window for a lithographic process, the process window describing a degree of acceptable variation in at least one processing parameter during the lithographic process. The method includes obtaining a set of output parameter values derived from measurements performed at a plurality of locations on a substrate, following pattern transfer to the substrate using a lithographic process, and obtaining a corresponding set of actual processing parameter values that includes an actual value of a processing parameter of the lithographic process during the pattern transfer at each of the plurality of locations. The process window is determined from the output parameter values and the actual processing parameter values. This process window may be used to improve the selection of the processing parameter at which a subsequent lithographic process is performed.

Abstract: A method of determining focus of a lithographic apparatus has the following steps. Using the lithographic process to produce first and second structures on the substrate, the first structure has features which have a profile that has an asymmetry that depends on the focus and an exposure perturbation, such as dose or aberration. The second structure has features which have a profile that is differently sensitive to focus than the first structure and which is differently sensitive to exposure perturbation than the first structure. Scatterometer signals are used to determine a focus value used to produce the first structure. This may be done using the second scatterometer signal, and/or recorded exposure perturbation settings used in the lithographic process, to select a calibration curve for use in determining the focus value using the first scatterometer signal or by using a model with parameters related to the first and second scatterometer signals.

Abstract: A method of determining focus of a lithographic apparatus has the following steps. Using the lithographic process to produce first and second structures on the substrate, the first structure has features which have a profile that has an asymmetry that depends on the focus and an exposure perturbation, such as dose or aberration. The second structure has features which have a profile that is differently sensitive to focus than the first structure and which is differently sensitive to exposure perturbation than the first structure. Scatterometer signals are used to determine a focus value used to produce the first structure. This may be done using the second scatterometer signal, and/or recorded exposure perturbation settings used in the lithographic process, to select a calibration curve for use in determining the focus value using the first scatterometer signal or by using a model with parameters related to the first and second scatterometer signals.

Abstract: A substrate has first and second target structures formed thereon by a lithographic process. Each target structure has two-dimensional periodic structure formed in a single material layer on a substrate using first and second lithographic steps, wherein, in the first target structure, features defined in the second lithographic step are displaced relative to features defined in the first lithographic step by a first bias amount that is close to one half of a spatial period of the features formed in the first lithographic step, and, in the second target structure, features defined in the second lithographic step are displaced relative to features defined in the first lithographic step by a second bias amount close to one half of said spatial period and different to the first bias amount.

Abstract: Disclosed is a method of monitoring a lithographic process parameter, such as focus and/or dose, of a lithographic process. The method comprises acquiring a first and a second target measurement using respectively a first measurement configuration and a second measurement configuration, and determining the lithographic process parameter from a first metric derived from said first target measurement and said second target measurement. The first metric may be difference. Also disclosed are corresponding measurement and lithographic apparatuses, a computer program and a method of manufacturing devices.

Abstract: Disclosed is a method of monitoring a focus parameter during a lithographic process. The method comprises acquiring first and second measurements of, respectively first and second targets, wherein the first and second targets have been exposed with a relative best focus offset. The method then comprises determining the focus parameter from first and second measurements. Also disclosed are corresponding measurement and lithographic apparatuses, a computer program and a method of manufacturing devices.

Abstract: A method and apparatus for obtaining focus information relating to a lithographic process. The method includes illuminating a target, the target having alternating first and second structures, wherein the form of the second structures is focus dependent, while the form of the first structures does not have the same focus dependence as that of the second structures, and detecting radiation redirected by the target to obtain for that target an asymmetry measurement representing an overall asymmetry of the target, wherein the asymmetry measurement is indicative of focus of the beam forming the target. An associated mask for forming such a target, and a substrate having such a target.

Abstract: A lithographic system includes a monitored lithographic projection apparatus arranged to project a patterned beam onto a substrate. A scatterometer measures a plurality of parameters of the pattern transferred to the substrate including at least one CD-profile parameter and at least one further parameter of the pattern transferred to the substrate which is indicative of a machine setting of the monitored lithographic projection apparatus. A matching system includes a database storing information representative of reference CD values and reference values for the further feature. A comparison arrangement compares the measured values with the corresponding stored values, a lithographic parameter calculation means calculating a corrected set of machine settings for the monitored lithographic apparatus dependent on the differences between the measured and reference values.

Abstract: A method of determining focus of a lithographic apparatus has the following steps. Using the lithographic process to produce first and second structures on the substrate, the first structure has features which have a profile that has an asymmetry that depends on the focus and an exposure perturbation, such as dose or aberration. The second structure has features which have a profile that is differently sensitive to focus than the first structure and which is differently sensitive to exposure perturbation than the first structure. Scatterometer signals are used to determine a focus value used to produce the first structure. This may be done using the second scatterometer signal, and/or recorded exposure perturbation settings used in the lithographic process, to select a calibration curve for use in determining the focus value using the first scatterometer signal or by using a model with parameters related to the first and second scatterometer signals.

Abstract: In order to determine whether an exposure apparatus is outputting the correct dose of radiation and a projection system of the exposure apparatus is focusing the radiation correctly, a test pattern is used on a mask for printing a specific marker onto a substrate. This marker may be measured by an inspection apparatus, such as, for example, a scatterometer to determine whether errors in focus, dose, and other related properties are present. The test pattern is arranged such that changes in focus and dose may be easily determined by measuring properties of a pattern that is exposed using the mask. The test pattern of the mask is arranged so that it gives rise to a marker pattern on the substrate surface. The marker pattern contains structures that have at least two measurable side wall angles. Asymmetry between side wall angles of a structure is related to focus (or defocus) of the exposure radiation from the exposure apparatus.

Abstract: A method of determining exposure dose of a lithographic apparatus used in a lithographic process on a substrate. Using the lithographic process to produce a first structure on the substrate, the first structure having a dose-sensitive feature which has a form that depends on exposure dose of the lithographic apparatus on the substrate. Using the lithographic process to produce a second structure on the substrate, the second structure having a dose-sensitive feature which has a form that depends on the exposure dose of the lithographic apparatus but which has a different sensitivity to the exposure dose than the first structure. Detecting scattered radiation while illuminating the first and second structures with radiation to obtain first and second scatterometer signals. Using the first and second scatterometer signals to determine an exposure dose value used to produce at least one of the first and second structures.

Abstract: A method is used to determine focus of a lithographic apparatus used in a lithographic process on a substrate. The lithographic process is used to form at least two periodic structures on the substrate. Each structure has at least one feature that has an asymmetry between opposing side wall angles that varies as a different function of the focus of the lithographic apparatus on the substrate. A spectrum produced by directing a beam of radiation onto the at least two periodic structures is measured and ratios of the asymmetries are determined. The ratios and a relationship between the focus and the side wall asymmetry for each structure is used to determine the focus of the lithographic apparatus on the substrate.