Abstract: Disclosed is a substrate and associated patterning device. The substrate comprises at least one target arrangement suitable for metrology of a lithographic process, the target arrangement comprising at least one pair of similar target regions which are arranged such that the target arrangement is, or at least the target regions for measurement in a single direction together are, centrosymmetric. A metrology method is also disclosed for measuring the substrate. A metrology method is also disclosed comprising which comprises measuring such a target arrangement and determining a value for a parameter of interest from the scattered radiation, while correcting for distortion of the metrology apparatus used.

Abstract: Disclosed is a method comprising measuring radiation reflected from a metrology target and decomposing the measured radiation in components, for example Fourier components or spatial components. Further, there is disclosed a recipe selection method which provides an algorithm to select a parameter of the metrology apparatus based on re-calculated dependencies of 5 the measured radiation based on single components.

Abstract: Techniques for determining a value of a parameter of interest of a patterning process are described. One such technique involves obtaining a plurality of calibration data units from one or more targets in a metrology process. Each calibration data unit of at least two of the calibration data units represents detected radiation obtained using different respective polarization settings in the metrology process, each polarization setting defining a polarization property of incident radiation of the metrology process and of detected radiation of the metrology process. The calibration data units are used to obtain calibration information about the metrology process. A measurement data unit representing detected radiation scattered from a further target is obtained, the further target having a structure formed using the patterning process on the substrate or on a further substrate. A value of the parameter of interest is determined using the measurement data unit and the obtained calibration information.

Abstract: The disclosure relates to measuring a parameter of a lithographic process and a metrology apparatus. In one arrangement, radiation from a radiation source is modified and used to illuminate a target formed on a substrate using the lithographic process. Radiation scattered from a target is detected and analyzing to determine the parameter. The modification of the radiation comprises modifying a wavelength spectrum of the radiation to have a local minimum between a global maximum and a local maximum, wherein the power spectral density of the radiation at the local minimum is less than 20% of the power spectral density of the radiation at the global maximum and the power spectral density of the radiation at the local maximum is at least 50% of the power spectral density of the radiation at the global maximum.

Abstract: The disclosure relates to methods of determining a value of a parameter of interest of a patterning process, and of cleaning a signal containing information about the parameter of interest. In one arrangement, first and second detected representations of radiation are obtained. The radiation is provided by redirection of polarized incident radiation by a structure. The first and second detected representations are derived respectively from first and second polarization components of the redirected radiation. An asymmetry in the first detected representation comprises a contribution from the parameter of interest and a contribution from one or more other sources of asymmetry. An asymmetry in the second detected representation comprises a larger contribution from said one or more other sources of asymmetry relative to a contribution from the parameter of interest. A combination of the first and second detected representations is used to determine a value of the parameter of interest.

Abstract: Techniques for determining a value of a parameter of interest of a patterning process are described. One such technique involves obtaining a plurality of calibration data units from one or more targets in a metrology process. Each calibration data unit of at least two of the calibration data units represents detected radiation obtained using different respective polarization settings in the metrology process, each polarization setting defining a polarization property of incident radiation of the metrology process and of detected radiation of the metrology process. The calibration data units are used to obtain calibration information about the metrology process. A measurement data unit representing detected radiation scattered from a further target is obtained, the further target having a structure formed using the patterning process on the substrate or on a further substrate. A value of the parameter of interest is determined using the measurement data unit and the obtained calibration information.

Abstract: The disclosure relates to methods of determining a value of a parameter of interest of a patterning process, and of cleaning a signal containing information about the parameter of interest. In one arrangement, first and second detected representations of radiation are obtained. The radiation is provided by redirection of polarized incident radiation by a structure. The first and second detected representations are derived respectively from first and second polarization components of the redirected radiation. An asymmetry in the first detected representation comprises a contribution from the parameter of interest and a contribution from one or more other sources of asymmetry. An asymmetry in the second detected representation comprises a larger contribution from said one or more other sources of asymmetry relative to a contribution from the parameter of interest. A combination of the first and second detected representations is used to determine a value of the parameter of interest.

Abstract: A scatterometer is used in a dark-field imaging mode to measure asymmetry-related parameters such as overlay. Measurements of small grating targets are made using identical optical paths, with the target in two orientations to obtain separate measurements of +1 and ?1 diffraction orders. In this way, intensity scaling differences (tool asymmetry) are avoided. However, additive intensity defects due to stray radiation (ghosts) in the optical system cannot be avoided. Additive intensity issues strongly depend on the ratio between 0th and 1st order diffraction and are therefore strongly substrate (process) dependent. Calibration measurements are made on a few representative target gratings having biases. The calibration measurements are made, using not only different substrate rotations but also complementary apertures. Corrections are calculated and applied to correct asymmetry, to reduce error caused by stray radiation.

Abstract: A scatterometer is used in a dark-field imaging mode to measure asymmetry-related parameters such as overlay. Measurements of small grating targets are made using identical optical paths, with the target in two orientations to obtain separate measurements of +1 and ?1 diffraction orders. In this way, intensity scaling differences (tool asymmetry) are avoided. However, additive intensity defects due to stray radiation (ghosts) in the optical system cannot be avoided. Additive intensity issues strongly depend on the ratio between 0th and 1st order diffraction and are therefore strongly substrate (process) dependent. Calibration measurements are made on a few representative target gratings having biases. The calibration measurements are made, using not only different substrate rotations but also complementary apertures. Corrections are calculated and applied to correct asymmetry, to reduce error caused by stray radiation.