A detection system (200) includes an illumination system (210), a first optical system (232), a phase modulator (220), a lock-in detector (255), and a function generator (230). The illumination system is configured to transmit an illumination beam (218) along an illumination path. The first optical system is configured to transmit the illumination beam toward a diffraction target (204) on a substrate (202). The first optical system is further configured to transmit a signal beam including diffraction order sub-beams (222, 224, 226) that are diffracted by the diffraction target. The phase modulator is configured to modulate the illumination beam or the signal beam based on a reference signal. The lock-in detector is configured to collect the signal beam and to measure a characteristic of the diffraction target based on the signal beam and the reference signal. The function generator is configured to generate the reference signal for the phase modulator and the lock-in detector.

Disclosed is a metrology device operable to measure a sample with measurement radiation and associated method. The metrology device comprises: an illumination branch operable to propagate measurement radiation to a sample, a detection branch operable to propagate one or more components of scattered radiation, scattered from said sample as a result of illumination of the sample by said measurement radiation; and a dispersive arrangement in either of said illumination branch or said detection branch. The dispersive arrangement is arranged to maintain one or more components of said scattered radiation at substantially a same respective location in a detection pupil plane over a range of wavelength values for said measurement radiation.

A metrology system includes an illumination source configured to generate an illumination beam, one or more illumination optics configured to direct the illumination beam to a sample, one or more collection optics configured to collect illumination emanating from the sample, a detector, and a hyperspectral imaging sub-system. The hyperspectral imaging sub-system includes a dispersive element positioned at a pupil plane of the set of collection optics configured to spectrally disperse the collected illumination, a lens array including an array of focusing elements, and one or more imaging optics. The one or more imaging optics combine the spectrally-dispersed collected illumination to form an image of the pupil plane on the lens array. The focusing elements of the lens array distribute the collected illumination on the detector in an arrayed pattern.

An optical system for a metrology system for measuring an object has an object holder for holding the object in an object plane. A transmissive optical focusing component is arranged in the beam path of illumination light between a light source of the metrology system and an object field in the object plane. The transmissive optical focusing component is used to generate an illumination focus in the subsequent beam path of the illumination light. The transmissive optical focusing component has a focal length which is smaller than 5 mm. A detection device is used for detecting the illumination light in the beam path downstream of the object field. An imaging optical unit is used for imaging the illumination focus generated by the transmissive optical focusing component into a further illumination focus in the region of the object field. The result is an optical system, the handling of which, in particular with respect to the object arrangement, is facilitated.

An optical system for a metrology system for measuring an object has an object holder for holding the object in an object plane. A transmissive optical focusing component is arranged in the beam path of illumination light between a light source of the metrology system and an object field in the object plane. The focusing component is used to generate an illumination focus in the region of the object field. A dispersive optical component is arranged in the beam path of the illumination light downstream of the object field. The dispersive optical component is used for at least partially spatially separating at least two wavelength components of the illumination light. A detection device comprising at least two sensor elements is used for at least partially separately detecting each of the different wavelength components of the illumination light in the beam path downstream of the dispersive optical component. The result is an optical system with improved measurement accuracy.

A metrology system comprises a radiation source, an optical element, first and second detectors, an integrated optical device comprising a multimode waveguide, and a processor. The radiation source generates radiation. The optical element directs radiation toward a target to generate scattered radiation from the target. The first detector receives a first portion of the scattered radiation and generates a first detection signal based on the received first portion. The multimode waveguide interferes a second portion of the scattered radiation using modes of the multimode waveguide. The second detector receives the interfered second portion and generates a second detection signal based on the received interfered second portion. The processor receives the first and second detection signals. The processor analyzes the received first portion, the received interfered second portion, and a propagation property of the multimode waveguide. The processor determines the property of the target based on the analysis.

An overlay metrology system may include an illumination source to generate illumination including two or more spectral bands having two or more center wavelengths. The system may include an optical sub-system to illuminate and image a sample, where the sample in accordance with the metrology recipe includes one or more cells with grating-over-grating structures formed as overlapping gratings with different pitches in different sample layers. The system may include collection pupil components to exclusively pass, for each of the two or more center wavelengths, two diffraction lobes from each of the different pitches of the grating-over-grating structures. A controller may receive images of the sample from the detectors generated in accordance with the metrology recipe and generate overlay measurements between at least some of the different layers of the sample based on the images.

An inspection apparatus includes a radiation source, an optical system, and a detector. The radiation source generates a beam of radiation. The optical system directs the beam along an optical axis and toward a target so as to produce scattered radiation from the target. The optical system includes a beam displacer including four reflective surfaces having a spatial arrangement. The beam displacer receives the beam along the optical axis, performs reflections of the beam so as to displace the optical axis of the beam, rotates to shift the displaced optical axis, and preserves polarization of the beam such that a polarization state of the beam along the deflected optical axis is invariant to the rotating based on the spatial arrangement of the four reflective surfaces. The detector receives the scattered radiation to generate a measurement signal based on the received scattered radiation.

Devices and processes for managing electrostatic charge on lithographic photomasks for semiconductor fabrication are provided. Exemplary devices include sensors for measuring the electrostatic charge on a lithographic photomask and charge injectors for modifying the electrostatic charge on a lithographic photomask. Exemplary devices are capable of attaching to carriers for lithographic photomasks. Exemplary processes include measuring the electrostatic charge on a lithographic photomask, calculating the amount that the electrostatic charge should be increased or decreased, and modifying the amount of electrostatic charge.

Disclosed is metrology apparatus for measurement of a diffractive structure on a substrate. comprising: a radiation source operable to provide first radiation for excitation of the diffractive structure, said first radiation having a first wavelength; a detection arrangement operable to detect at least diffracted second radiation comprising a second harmonic of said first radiation, said diffracted second radiation being generated from said diffractive structure and/or substrate and diffracted by said diffractive structure; and a processing arrangement operable to determine a parameter of interest relating to said diffractive structure from at least said diffracted second radiation.