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: Methods and apparatus for measuring a parameter of interest of a target structure formed on substrate are disclosed. In one arrangement, the target structure comprises a first sub-target and a second sub-target. The first sub-target comprises a first bias and the second sub-target comprises a second bias. The method comprises determining the parameter of interest using a detected or estimated reference property of radiation at a first wavelength scattered from the first sub-target and a detected or estimated reference property of radiation at a second wavelength scattered from the second sub-target. The first wavelength is different to the second wavelength.

Abstract: A scatterometer performs diffraction based measurements of one or more parameters of a target structure. To make two-color measurements in parallel, the structure is illuminated simultaneously with first radiation (302) having a first wavelength and a first angular distribution and with second radiation (304) having a second wavelength and a second angular distribution. The collection path (CP) includes a segmented wavelength-selective filter (21, 310) arranged to transmit wanted higher order portions of the diffracted first radiation (302X, 302Y) and of the diffracted second radiation (304X, 304Y), while simultaneously blocking zero order portions (302?, 304?) of both the first radiation and second radiation.

Abstract: Methods of measuring a target formed by a lithographic process, a metrology apparatus and a polarizer assembly are disclosed. The polarizer assembly comprises a polarizing structure having a substantially planar form and configured to polarize radiation passing there through in a circular polarizing region. The circular polarizing region is configured to apply a first polarization to radiation passing through a first one of two pairs of diametrically opposite quadrants of the circular polarizing region and to apply a second polarization, orthogonal to the first polarization, to radiation passing through a second one of two pairs of diametrically opposite quadrants of the circular polarizing region.

Abstract: A method of adjusting a metrology apparatus, the method including: spatially dividing an intensity distribution of a pupil plane of the metrology apparatus into a plurality of pixels; and reducing an effect of a structural asymmetry in a target on a measurement by the metrology apparatus on the target, by adjusting intensities of the plurality of pixels.

Abstract: A radiation receiving system for an inspection apparatus, used to perform measurements on target structures on lithographic substrates as part of a lithographic process, comprises a spectrometer with a number of inputs. The radiation receiving system comprises: a plurality of inputs, each input being arranged to provide radiation from a target structure; a first optical element operable to receive radiation from each of the plurality of inputs; a second optical element operable to receive radiation from the first optical element and to scatter the radiation; and a third optical element operable to direct the scattered radiation onto a detector. The second optical element may for example be a reflective diffraction grating that diffracts incoming radiation into an output radiation spectrum.

Abstract: A method of adjusting a metrology apparatus, the method including: spatially dividing an intensity distribution of a pupil plane of the metrology apparatus into a plurality of pixels; and reducing an effect of a structural asymmetry in a target on a measurement by the metrology apparatus on the target, by adjusting intensities of the plurality of pixels.

Abstract: Methods and apparatuses for measuring a plurality of structures formed on a substrate are disclosed. In one arrangement, a method includes obtaining data from a first measurement process. The first measurement process including individually measuring each of the plurality of structures to measure a first property of the structure. A second measurement process is used to measure a second property of each of the plurality of structures. The second measurement process includes illuminating each structure with radiation having a radiation property that is individually selected for that structure using the measured first property for the structure.

Abstract: A method comprising: evaluating a plurality of polarization characteristics associated with measurement of a metrology target of a substrate processed using a patterning process, against one or more measurement quality parameters; and selecting one or more polarization characteristics from the plurality of polarization characteristics based on one or more of the measurement quality parameters.

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 metrology apparatus is disclosed that measures a structure formed on a substrate to determine a parameter of interest. The apparatus comprises an optical system configured to focus radiation onto the structure and direct radiation after reflection from the structure onto a detector, wherein: the optical system is configured such that the detector detects a radiation intensity resulting from interference between radiation from at least two different points in a pupil plane field distribution, wherein the interference is such that a component of the detected radiation intensity containing information about the parameter of interest is enhanced relative to one or more other components of the detected radiation intensity.

Abstract: Disclosed is a metrology sensor system, such as a position sensor. The system comprises an optical collection system configured to collect diffracted or scattered radiation from a metrology mark on a substrate, said collected radiation comprising at least one parameter-sensitive signal and noise signal which is not parameter-sensitive, a processing system operable to process the collected radiation; and a module housing. An optical guide is provided for guiding the at least one parameter-sensitive signal, separated from the noise signal, from the processing system to a detection system outside of the housing. A detector detects the separated at least one parameter-sensitive signal. An obscuration for blocking zeroth order radiation and/or a demagnifying optical system may be provided between the optical guide and the detector.

Abstract: Disclosed is a method and associated inspection apparatus for measuring a characteristic of interest relating to a structure on a substrate. The inspection apparatus uses measurement radiation comprising a plurality of wavelengths. The method comprises performing a plurality of measurement acquisitions of said structure, each measurement acquisition being performed using measurement radiation comprising a different subset of the plurality of wavelengths, to obtain a plurality of multiplexed measurement signals. The plurality of multiplexed measurement signals are subsequently de-multiplexed into signal components according to each of said plurality of wavelengths, to obtain a plurality of de-multiplexed measurement signals which are separated according to wavelength.

Abstract: A metrology apparatus for determining a characteristic of interest of a structure on a substrate, the apparatus comprising: a radiation source for generating illumination radiation; at least two illumination branches for illuminating the structure on the substrate, the illumination branches being configured to illuminate the structure from different angles; and a radiation switch configured to receive the illumination radiation and transfer at least part of the radiation to a selectable one of the at least two illumination branches.

Abstract: A metrology apparatus for determining a parameter of interest of a structure formed by a lithographic process on a substrate, the metrology apparatus comprising: an illuminator for illuminating the structure; a lens for collecting at least a portion of radiation diffracted from the structure; and an image sensor for receiving and obtaining a recording of the collected diffracted radiation; wherein the illuminator comprises at least one optical fiber for illuminating the structure directly.

Abstract: A metrology apparatus is disclosed that has an optical system to focus radiation onto a structure and directs redirected radiation from the structure to a detection system. The optical system applies a plurality of different offsets of an optical characteristic to radiation before and/or after redirected by the structure, such that a corresponding plurality of different offsets are provided to redirected radiation derived from a first point of a pupil plane field distribution relative to redirected radiation derived from a second point of the pupil plane field distribution. The detection system detects a corresponding plurality of radiation intensities resulting from interference between the redirected radiation derived from the first point of the pupil plane field distribution and the redirected radiation derived from the second point of the pupil plane field distribution. Each radiation intensity corresponds to a different one of the plurality of different offsets.

Abstract: A metrology tool for determining a parameter of interest of a structure fabricated on a substrate, the metrology tool comprising: an illumination optical system for illuminating the structure with illumination radiation under a non-zero angle of incidence; a detection optical system comprising a detection optical sensor and at least one lens for capturing a portion of illumination radiation scattered by the structure and transmitting the captured radiation towards the detection optical sensor, wherein the illumination optical system and the detection optical system do not share an optical element.

Abstract: Measurement system comprising a radiation source configured to generate a measurement radiation beam, a polarizer and a grating to receive the measurement radiation beam and provide a polarized measurement radiation beam patterned by the grating, optics to form an image of the grating at a target location on a substrate. The image comprises a first part having a first polarization and a second part having a second polarization, detection optics to receive radiation from the target location of the substrate and form an image of the grating image at a second grating, and a detector to receive radiation transmitted through the second grating and produce a two output signal indicative of the intensity of the transmitted radiation for the first and second parts of the grating image respectively. Topography of the substrate can be determined from the signals.

Abstract: A scatterometer performs diffraction based measurements of one or more parameters of a target structure. To make two-color measurements in parallel, the structure is illuminated simultaneously with first radiation (302) having a first wavelength and a first angular distribution and with second radiation (304) having a second wavelength and a second angular distribution. The collection path (CP) includes a segmented wavelength-selective filter (21, 310) arranged to transmit wanted higher order portions of the diffracted first radiation (302X, 302Y) and of the diffracted second radiation (304X, 304Y), while simultaneously blocking zero order portions (302?, 304?) of both the first radiation and second radiation.

Abstract: A metrology apparatus is disclosed that has an optical system to focus radiation onto a structure and directs redirected radiation from the structure to a detection system. The optical system applies a plurality of different offsets of an optical characteristic to radiation before and/or after redirected by the structure, such that a corresponding plurality of different offsets are provided to redirected radiation derived from a first point of a pupil plane field distribution relative to redirected radiation derived from a second point of the pupil plane field distribution. The detection system detects a corresponding plurality of radiation intensities resulting from interference between the redirected radiation derived from the first point of the pupil plane field distribution and the redirected radiation derived from the second point of the pupil plane field distribution. Each radiation intensity corresponds to a different one of the plurality of different offsets.