Abstract: Radiation source assembly and method for generating broadband radiation by spectral broadening. The radiation source assembly includes a pump assembly configured to provide broadband input radiation. The pump assembly includes a pump source configured to provide first radiation at a pump wavelength, and a broadband assembly configured to provide second radiation including a continuous wavelength range, wherein the first radiation and the second radiation form the broadband input radiation. The radiation source assembly further includes an optical fibre configured to receive the broadband input radiation. The optical fibre includes a core configured along at least a part of the length of the fibre to guide the received broadband input radiation during propagation through the fibre, so as to generate broadband radiation by spectral broadening to be output by the fibre.

Abstract: A method of producing photonic crystal fibers (PCFs) is disclosed, the method includes: 1) obtaining an intermediate PCF having an initial outer fiber diameter of less than 1 mm; and 2) elongating the intermediate PCF so as to controllably reduce at least one dimension of the intermediate PCF.

Abstract: Apparatuses and techniques for suppressing a zeroth order portion of a configured radiation beam. In some embodiments, an extreme ultraviolet (EUV) lithographic apparatus for forming an image on a substrate by use of an EUV radiation beam that is configured by a patterning device comprising a pattern of reflective regions and partially reflective regions, wherein the partially reflective regions are configured to suppress and apply a phase shift to a portion of the EUV radiation beam, may include a projection system. The projection system may be configured to suppress a zeroth order portion of a configured EUV radiation beam, and direct an unsuppressed portion of a configured EUV radiation beam towards a substrate to form an image on the substrate.

Abstract: A two-dimensional diffraction grating for a phase-stepping measurement system for determining an aberration map for a projection system comprises a substrate provided with a square array of through-apertures, wherein the diffraction grating is self-supporting. It will be appreciated that for a substrate provided with a square array of through-apertures to be self-supporting at least some substrate material is provided between each through-aperture and the adjacent through apertures. A method of designing a two-dimensional diffraction grating for a phase-stepping measurement system for determining an aberration map for a projection system comprises: selecting a general geometry for the two-dimensional diffraction grating, the general geometry having at least one parameter; and selecting values for the least one parameter that result in a grating efficiency map for the two-dimensional diffraction grating so as to control the contributions to a first harmonic of a phase stepping signal.

Abstract: A method for improving a lithographic process of imaging a portion of a design layout onto a substrate using a lithographic apparatus. The method includes computing a multi-variable cost function that is a function of: (i) a plurality of design variables that affect characteristics of the lithographic process and (ii) a radiation bandwidth of a radiation source of the lithographic apparatus; and reconfiguring one or more of the characteristics (e.g., EPE, image contrast, resist, etc.) of the lithographic process by adjusting one or more of the design variables (e.g., source, mask layout, bandwidth, etc.) until a termination condition is satisfied. The termination condition includes a speckle characteristic (e.g., a speckle contrast) maintained within a speckle specification associated with the radiation source and also maintaining an image contrast associated with the lithographic process within a desired range. The speckle characteristic being a function of the radiation bandwidth.

Abstract: Apparatuses and techniques for suppressing a zeroth order portion of a configured radiation beam. In some embodiments, an extreme ultraviolet (EUV) lithographic apparatus for forming an image on a substrate by use of an EUV radiation beam that is configured by a patterning device comprising a pattern of reflective regions and partially reflective regions, wherein the partially reflective regions are configured to suppress and apply a phase shift to a portion of the EUV radiation beam, may include a projection system. The projection system may be configured to suppress a zeroth order portion of a configured EUV radiation beam, and direct an unsuppressed portion of a configured EUV radiation beam towards a substrate to form an image on the substrate.

Abstract: A metrology system includes a radiation source, first, second, and third optical systems, and a processor. The first optical system splits the radiation into first and second beams of radiation and impart one or more phase differences between the first and second beams. The second optical system directs the first and second beams toward a target structure to produce first and second scattered beams of radiation. The third optical system interferes the first and second scattered beams at an imaging detector. The imaging detector generates a detection signal based on the interfered first and second scattered beams. The metrology system modulates one or more phase differences of the first and second scattered beams based on the imparted one or more phase differences. The processor analyzes the detection signal to determine a property of the target structure based on at least the modulated one or more phase differences.

Abstract: A method for determining a component of optical characteristic of a patterning process. The method includes obtaining (i) a plurality of desired features, (ii) a plurality of simulated features based on the plurality of desired features and an optical characteristic of a patterning apparatus, and (iii) a performance metric (e.g., EPE) related to a desired feature of the plurality of desired features and an associated simulated feature of the plurality of simulated features; determining a set of optical sensitivities of the patterning process by computing a change in value of the performance metric based on a change in value of the optical characteristic; and identifying, based on the set of optical sensitivities, a set of components (e.g., principal components) of the optical characteristic that include dominant contributors in changing the value of the performance metric.

Abstract: A method for tuning a target apparatus of a patterning process. The method includes obtaining a reference performance, and measurement data of a substrate subjected to the patterning process at the target apparatus, the measurement data indicative of a performance of the target apparatus; determining a cause of a performance mismatch based on a difference between the reference performance and the performance of the target apparatus, wherein the cause includes an optical characteristic; and responsive to the cause, adjusting an optical parameter associated with an adjustable optical characteristic to reduce the performance mismatch in the optical characteristic.

Abstract: A radiation system comprising a radiation source and a radiation conditioning apparatus, wherein the radiation source is configured to provide a radiation beam with wavelengths which extend from ultraviolet to infrared, and wherein the radiation conditioning apparatus is configured to separate the radiation beam into at least two beam portions and is further configured to condition the at least two beam portions differently.

Abstract: A method for determining a component of optical characteristic of a patterning process. The method includes obtaining (i) a plurality of desired features, (ii) a plurality of simulated features based on the plurality of desired features and an optical characteristic of a patterning apparatus, and (iii) a performance metric (e.g., EPE) related to a desired feature of the plurality of desired features and an associated simulated feature of the plurality of simulated features; determining a set of optical sensitivities of the patterning process by computing a change in value of the performance metric based on a change in value of the optical characteristic; and identifying, based on the set of optical sensitivities, a set of components (e.g., principal components) of the optical characteristic that include dominant contributors in changing the value of the performance metric.

Abstract: Apparatuses and techniques for suppressing a zeroth order portion of a configured radiation beam. In some embodiments, an extreme ultraviolet (EUV) lithographic apparatus for forming an image on a substrate by use of an EUV radiation beam that is configured by a patterning device comprising a pattern of reflective regions and partially reflective regions, wherein the partially reflective regions are configured to suppress and apply a phase shift to a portion of the EUV radiation beam, may include a projection system. The projection system may be configured to suppress a zeroth order portion of a configured EUV radiation beam, and direct an unsuppressed portion of a configured EUV radiation beam towards a substrate to form an image on the substrate.

Abstract: A radiation system comprising a radiation source and a radiation conditioning apparatus, wherein the radiation source is configured to provide a radiation beam with wavelengths which extend from ultraviolet to infrared, and wherein the radiation conditioning apparatus is configured to separate the radiation beam into at least two beam portions and is further configured to condition the at least two beam portions differently.

Abstract: Method of determining a photodetector contribution to a measurement of apodization of a projection system of an immersion lithography apparatus, the method comprising providing a beam of radiation, illuminating an object with the beam of radiation, using the projection system to project an image of the object through a liquid layer and onto a photodetector, performing a first set of measurements of radiation intensity across a pupil plane of the projection system at a first liquid layer thickness, performing a second set of measurements of radiation intensity across the pupil plane of the projection system at a different liquid layer thickness, determining a set of intensity differences from the first set of measurements and the second set of measurements, comparing the determined set of intensity differences to an expected set of intensity difference, and using the results of the comparison to determine the photodetector contribution to a measurement of apodization.

Abstract: A method for tuning a target apparatus of a patterning process. The method includes obtaining a reference performance, and measurement data of a substrate subjected to the patterning process at the target apparatus, the measurement data indicative of a performance of the target apparatus; determining a cause of a performance mismatch based on a difference between the reference performance and the performance of the target apparatus, wherein the cause includes an optical characteristic; and responsive to the cause, adjusting an optical parameter associated with an adjustable optical characteristic to reduce the performance mismatch in the optical characteristic.

Abstract: Method of determining a photodetector contribution to a measurement of apodization of a projection system of an immersion lithography apparatus, the method comprising providing a beam of radiation, illuminating an object with the beam of radiation, using the projection system to project an image of the object through a liquid layer and onto a photodetector, performing a first set of measurements of radiation intensity across a pupil plane of the projection system at a first liquid layer thickness, performing a second set of measurements of radiation intensity across the pupil plane of the projection system at a different liquid layer thickness, determining a set of intensity differences from the first set of measurements and the second set of measurements, comparing the determined set of intensity differences to an expected set of intensity difference, and using the results of the comparison to determine the photodetector contribution to a measurement of apodization.

Abstract: A method for quantifying the effect of pupil function variations on a lithographic effect within a lithographic apparatus is disclosed. The method comprises: determining a discrete, two-dimensional sensitivity map in a pupil plane of the lithographic apparatus, wherein the lithographic effect is given by the inner product of said sensitivity map with a discrete, two-dimensional pupil function variation map of a radiation beam in the pupil plane. The pupil plane of a lithographic apparatus generally refers to the exit pupil of a projection system of the lithographic apparatus. Pupil function variations may comprise: relative phase variations within the pupil plane and/or relative intensity variations within the pupil plane.

Abstract: An optical system comprising: an illumination system configured, to form a periodic illumination mode comprising radiation in a pupil plane of the optical system having a spatial intensity profile which is periodic in at least one direction, a measurement system configured to measure a dose of radiation which is received in an field plane of the optical system as a function of position in the field plane, and a controller configured to: select one or more spatial frequencies in the field plane at which variation in the received dose of radiation as a function of position is caused by speckle, and determine a measure of the variation of the received dose of radiation as a function of position at the selected one or more spatial frequencies, the measure of the variation in the received dose being indicative of speckle in the field plane.

Abstract: A two-dimensional diffraction grating for a phase-stepping measurement system for determining an aberration map for a projection system comprises a substrate provided with a square array of through-apertures, wherein the diffraction grating is self-supporting. It will be appreciated that for a substrate provided with a square array of through-apertures to be self-supporting at least some substrate material is provided between each through-aperture and the adjacent through apertures. A method of designing a two-dimensional diffraction grating for a phase-stepping measurement system for determining an aberration map for a projection system comprises: selecting a general geometry for the two-dimensional diffraction grating, the general geometry having at least one parameter; and selecting values for the least one parameter that result in a grating efficiency map for the two-dimensional diffraction grating so as to control the contributions to a first harmonic of a phase stepping signal.

Abstract: A measurement method comprising using multiple radiation poles to illuminate a diffraction grating on a mask at a mask side of a projection system of a lithographic apparatus, coupling at least two different resulting diffraction orders per illumination pole through the projection system, using the projection system to project the diffraction orders onto a grating on a wafer such that a pair of combination diffraction orders is formed by diffraction of the diffraction orders, coupling the combination diffraction orders back through the projection system to detectors configured to measure the intensity of the combination diffraction orders, and using the measured intensity of the combination diffraction orders to measure the position of the wafer grating.