Abstract: A method including: for a metrology target, having a first biased target structure and a second differently biased target structure, created using a patterning process, obtaining metrology data including signal data for the first target structure versus signal data for the second target structure, the metrology data being obtained for a plurality of different metrology recipes and each metrology recipe specifying a different parameter of measurement; determining a statistic, fitted curve or fitted function through the metrology data for the plurality of different metrology recipes as a reference; and identifying at least two different metrology recipes that have a variation of the collective metrology data of the at least two different metrology recipes from a parameter of the reference that crosses or meets a certain threshold.

Abstract: A method of measuring a position of an alignment target on a substrate using an optical system. The method includes measuring a sub-segmented target by illuminating the sub-segmented target with radiation and detecting radiation diffracted by the sub-segmented target using a detector system to obtain signals containing positional information of the one sub-segmented target. The sub-segmented target has structures arranged periodically in at least a first direction, at least some of the structures including smaller sub-structures, and each sub-segmented target is formed with a positional offset between the structures and the sub-structures that is a combination of both known and unknown components. The signals, together with information on differences between known offsets of the sub-segmented target are used to calculate a measured position of an alignment target which is corrected for the unknown component of the positional offset.

Abstract: A lithographic apparatus comprises comprise a substrate table constructed to hold a substrate; and a sensor configured to sense a position of an alignment mark provided onto the substrate held by the substrate table. The sensor comprises a source of radiation configured to illuminate the alignment mark with a radiation beam, a detector configured to detect the radiation beam, having interacted with the alignment mark, as an out of focus optical pattern, and a data processing system. The data processing system is configured to receive image data representing the out of focus optical pattern, and process the image data for determining alignment information, comprising applying a lensless imaging algorithm to the out of focus optical pattern.

Abstract: Target structures such as overlay gratings (Ta and Tb) are formed on a substrate (W) by a lithographic process. The first target is illuminated with a spot of first radiation (456a, Sa) and simultaneously the second target is illuminated with a spot of second radiation (456b, Sb). A sensor (418) detects at different locations, portions (460x?, 460x+) of said first radiation that have been diffracted in a first direction by features of the first target and portions (460y?, 460y+) of said second radiation that have been diffracted in a second direction by features of the second target. Asymmetry in X and Y directions can be detected simultaneously, reducing the time required for overlay measurements in X and Y. The two spots of radiation at soft x-ray wavelength can be generated simply by exciting two locations (710a, 710b) in a higher harmonic generation (HHG) radiation source or inverse Compton scattering source.

Abstract: A method of determining the position of an alignment mark on a substrate, the alignment mark having first and second segment, the method including illuminating the alignment mark with radiation, detecting radiation diffracted by the alignment mark and generating a resulting alignment signal. The alignment signal has a first component received during illumination of the first segment only, a second component received during illumination of the second segment only, and a third component received during simultaneous illumination of both segments. The positions of the segments are determined using the first component, the second component and the third component of the alignment signal.

Abstract: Disclosed is a high harmonic generation (HHG) radiation source which may be used to generate measurement radiation for an inspection apparatus. In such a radiation source, a pump radiation source is operable to emit pump radiation at a high harmonic generation gas medium thereby exciting the high harmonic generation gas medium within a pump radiation interaction region so as to generate the high harmonic radiation and an ionization radiation source is operable to emit ionization radiation at the high harmonic generation gas medium to ionize a gas at an ionization region between the pump radiation interaction region and an optical output of the illumination source.

Abstract: An alignment sensor for a lithographic apparatus has an optical system configured to deliver, collect and process radiation selectively in a first waveband (e.g. 500-900 nm) and/or in a second waveband (e.g. 1500-2500 nm). The radiation of the first and second wavebands share a common optical path in at least some portion of the optical system, while the radiation of the first waveband is processed by a first processing sub-system and the radiation of the second waveband is processed by a second processing sub-system. The processing subsystems in one example include self-referencing interferometers. The radiation of the second waveband allows marks to be measured through an opaque layer. Optical coatings and other components of each processing sub-system can be tailored to the respective waveband, without completely duplicating the optical system.

Abstract: Disclosed is an inspection apparatus and associated method for measuring a target structure on a substrate. The inspection apparatus comprises an illumination source for generating measurement radiation; an optical arrangement for focusing the measurement radiation onto said target structure; and a compensatory optical device. The compensatory optical device may comprise an SLM operable to spatially modulate the wavefront of the measurement radiation so as to compensate for a non-uniform manufacturing defect in said optical arrangement. In alternative embodiments, the compensatory optical device may be located in the beam of measurement radiation, or in the beam of pump radiation used to generate high harmonic radiation in a HHG source. Where located in in the beam of pump radiation, the compensatory optical device may be used to correct pointing errors, or impart a desired profile or varying illumination pattern in a beam of the measurement radiation.

Abstract: Disclosed is a method of performing a measurement in an inspection apparatus; and an associated inspection apparatus and HHG source. The method comprises configuring one or more controllable characteristics of at least one driving laser pulse of a high harmonic generation radiation source to control the output emission spectrum of illumination radiation provided by the high harmonic generation radiation source; and illuminating a target structure with said illuminating radiation. The method may comprise configuring the driving laser pulse so that the output emission spectrum comprises a plurality of discrete harmonic peaks. Alternatively the method may comprise using a plurality of driving laser pulses of different wavelengths such that the output emission spectrum is substantially monochromatic.

Abstract: Disclosed is an illumination source for generating measurement radiation for an inspection apparatus. The source generates at least first measurement radiation and second measurement radiation such that the first measurement radiation and the second measurement radiation interfere to form combined measurement radiation modulated with a beat component. The illumination source may be a HHG source. Also disclosed is an inspection apparatus comprising such a source and an associated inspection method.

Abstract: Disclosed is a method, and associated apparatuses, for measuring a parameter of interest relating to a structure having at least two layers. The method comprises illuminating the structure with measurement radiation and detecting scattered radiation having been scattered by said structure. The scattered radiation comprises normal and complementary higher diffraction orders. A scatterometry model which relates a scattered radiation parameter to at least a parameter of interest and an asymmetry model which relates the scattered radiation parameter to at least one asymmetry parameter are defined, the asymmetry parameter relating to one or more measurement system errors and/or an asymmetry in the target other than a misalignment between the two layers. A combination of the scatterometry model and asymmetry model is used to determine a system of equations, and the system of equations is then solved for the parameter of interest.

Abstract: A method including directing, by an optical system, an illumination beam to a surface of a substrate, providing relative motion between the directed illumination beam and the substrate until the directed illumination beam is illuminated on a grating underneath an edge or a notch of the substrate, diffracting, by the grating, at least a portion of the illumination beam, and detecting, by the detector, the diffracted illumination.

Abstract: A method to determine a patterning process parameter, the method comprising: for a target, calculating a first value for an intermediate parameter from data obtained by illuminating the target with radiation comprising a central wavelength; for the target, calculating a second value for the intermediate parameter from data obtained by illuminating the target with radiation comprising two different central wavelengths; and calculating a combined measurement for the patterning process parameter based on the first and second values for the intermediate parameter.

Abstract: A method of determining positions of marks, the marks comprising periodic structures, at least some of the structures comprising periodic sub-structures, the sub-structures having a smaller period than the structures, the marks formed with positional offsets between the sub-structures and structures, the positional offsets caused by a combination of both known and unknown components, the method comprising illuminating a plurality of the marks with radiation having different characteristics, detecting radiation diffracted by the marks using one or more detectors which produce output signals, discriminating between constituent parts of the signals, the discriminating based on a variation of the signals as a function of spatial positions of the marks on a substrate, selecting at least one of the constituent parts of the signals, and using the at least one selected constituent part, and information relating to differences between the known components, to calculate a corrected position of at least one mark.

Abstract: Disclosed is a method of performing a measurement in an inspection apparatus, and an associated inspection apparatus and HHG source. The method comprises configuring one or more controllable characteristics of at least one driving laser pulse of a high harmonic generation radiation source to control the output emission spectrum of illumination radiation provided by the high harmonic generation radiation source; and illuminating a target structure with said illuminating radiation. The method may comprise configuring the driving laser pulse so that the output emission spectrum comprises a plurality of discrete harmonic peaks. Alternatively the method may comprise using a plurality of driving laser pulses of different wavelengths such that the output emission spectrum is substantially monochromatic.

Abstract: An apparatus and method for estimating a parameter of a lithographic process and an apparatus and method for determining a relationship between a measure of quality of an estimate of a parameter of a lithographic process are provided. In the apparatus for estimating the parameter a processor is configured to determine a quality of the estimate of the parameter relating to the tested substrate based on a measure of feature asymmetry in the at least first features of the tested substrate and further based on a relationship determined for a plurality of corresponding at least first features of at least one further substrate representative of the tested substrate, the relationship being between a measure of quality of an estimate of the parameter relating to the at least one further substrate and a measure of feature asymmetry in the corresponding first features.

Abstract: Disclosed are a method, computer program and a metrology apparatus for measuring a process effect parameter relating to a manufacturing process for manufacturing integrated circuits on a substrate. The method comprises determining for a structure, a first quality metric value for a quality metric from a plurality of measurement values each relating to a different measurement condition while cancelling or mitigating for the effect of the process effect parameter on the plurality of measurement values and a second quality metric value for the quality metric from at least one measurement value relating to at least one measurement condition without cancelling or mitigating for the effect of the process effect parameter on the at least one measurement value. The process effect parameter value for the process effect parameter can then be calculated from the first quality metric value and the second quality metric value, for example by calculating their difference.

Abstract: A method including: for a metrology target, having a first biased target structure and a second differently biased target structure, created using a patterning process, obtaining metrology data including signal data for the first target structure versus signal data for the second target structure, the metrology data being obtained for a plurality of different metrology recipes and each metrology recipe specifying a different parameter of measurement; determining a statistic, fitted curve or fitted function through the metrology data for the plurality of different metrology recipes as a reference; and identifying at least two different metrology recipes that have a variation of the collective metrology data of the at least two different metrology recipes from a parameter of the reference that crosses or meets a certain threshold.

Abstract: Disclosed is an inspection apparatus and associated method for measuring a target structure on a substrate. The inspection apparatus comprises an illumination source for generating measurement radiation; an optical arrangement for focusing the measurement radiation onto said target structure; and a compensatory optical device. The compensatory optical device may comprise an SLM operable to spatially modulate the wavefront of the measurement radiation so as to compensate for a non-uniform manufacturing defect in said optical arrangement. In alternative embodiments, the compensatory optical device may be located in the beam of measurement radiation, or in the beam of pump radiation used to generate high harmonic radiation in a HHG source. Where located in the beam of pump radiation, the compensatory optical device may be used to correct pointing errors, or impart a desired profile or varying illumination pattern in a beam of the measurement radiation.

Abstract: A metrology apparatus (302) includes a higher harmonic generation (HHG) radiation source for generating (310) EUV radiation. Operation of the HHG source is monitored using a wavefront sensor (420) which comprises an aperture array (424, 702) and an image sensor (426). A grating (706) disperses the radiation passing through each aperture so that the image detector captures positions and intensities of higher diffraction orders for different spectral components and different locations across the beam. In this way, the wavefront sensor can be arranged to measure a wavefront tilt for multiple harmonics at each location in said array. In one embodiment, the apertures are divided into two subsets (A) and (B), the gratings (706) of each subset having a different direction of dispersion. The spectrally resolved wavefront information (430) is used in feedback control (432) to stabilize operation of the HGG source, and/or to improve accuracy of metrology results.