Abstract: Provided are light sources and methods of controlling them, and devices and methods for use in measurement applications, particularly in metrology, for example in a lithographic apparatus. The methods and devices provide mechanisms for detection and/or correction of variations in the light source, in particular stochastic variations. Feedback or feedforward approaches can be used for the correction of the source and/or the metrology outputs. An exemplary method of controlling the spectral output of a light source which emits a time-varying spectrum of light includes the steps of: determining at least one characteristic of the spectrum of light emitted from the light source; and using said determined characteristic to control the spectral output.

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: A system includes an illumination system, an optical element, a switching element and a detector. The illumination system includes a broadband light source that generates a beam of radiation. The dispersive optical element receives the beam of radiation and generates a plurality of light beams having a narrower bandwidth than the broadband light source. The optical switch receives the plurality of light 5 beams and transmits each one of the plurality of light beams to a respective one of a plurality of alignment sensor of a sensor array. The detector receives radiation returning from the sensor array and to generate a measurement signal based on the received radiation.

Abstract: A system includes an illumination system, an optical element, and a detector. The optical system is implemented on a substrate. The illumination system includes first and second sources and first and second generators. The illumination system generates a beam of radiation. The first and second sources generate respective first and second different wavelength bands. The first and second resonators are optically coupled to respective ones of the first and second sources and narrow respective ones of the first and second wavelength bands. The optical element directs the beam toward a target structure. The detector receives radiation from the target structure and to generate a measurement signal based on the received radiation.

Abstract: A lithographic apparatus (LA) applies a pattern to a substrate (W). The lithographic apparatus includes a height sensor (LS), a substrate positioning subsystem, and a controller configured for causing the height sensor to measure the height (h) of the substrate surface at locations across the substrate. The measured heights are used to control the focusing of one or more patterns applied to the substrate. The height h is measured relative to a reference height (zref). The height sensor is operable to vary the reference height (zref), which allows a wider effective range of operation. Specifications for control of the substrate height during measurement can be relaxed. The reference height can be varied by moving one or more optical elements (566, 572, 576, 504 and/or 512) within the height sensor, or moving the height sensor. An embodiment without moving parts includes a multi-element photodetector (1212).

Abstract: Provided are light sources and methods of controlling them, and devices and methods for use in measurement applications, particularly in metrology, for example in a lithographic apparatus. The methods and devices provide mechanisms for detection and/or correction of variations in the light source, in particular stochastic variations. Feedback or feedforward approaches can be used for the correction of the source and/or the metrology outputs. An exemplary method of controlling the spectral output of a light source which emits a time-varying spectrum of light includes the steps of: determining at least one characteristic of the spectrum of light emitted from the light source; and using said determined characteristic to control the spectral output.

Abstract: Disclosed is a detection apparatus for simultaneous acquisition of multiple images of an object at a plurality of different focus levels; comprising: a modulator for obtaining multiple beam copies of an incoming beam; and a detector operable to capture said multiple beam copies, such that at two of said multiple beam copies are captured at different focus levels. Also disclosed is an inspection apparatus comprising such a detection system.

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: 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: The invention provides a level sensor to measure a position of a surface of a substrate, comprising a projection unit arranged to direct a beam of radiation to the surface of the substrate and a detection unit. The detection unit comprises a detection grating arranged to receive the beam of radiation reflected on the surface of the substrate, one or more detectors, one or more optical elements to direct the beam of radiation from the detection grating to the one or more detectors, and a processing unit to determine the position of the surface of the substrate on the basis of the beam of radiation received by the one or more detectors. The detection grating and the one or more optical elements are integrated in a single integrated optical element.

Abstract: The invention provides a level sensor to measure a position of a surface of a substrate, comprising a projection unit arranged to direct a beam of radiation to the surface of the substrate and a detection unit. The detection unit comprises a detection grating arranged to receive the beam of radiation reflected on the surface of the substrate, one or more detectors, one or more optical elements to direct the beam of radiation from the detection grating to the one or more detectors, and a processing unit to determine the position of the surface of the substrate on the basis of the beam of radiation received by the one or more detectors. The detection grating and the one or more optical elements are integrated in a single integrated optical element.

Abstract: A lithographic apparatus (LA) applies a pattern to a substrate (W). The lithographic apparatus includes a height sensor (LS), a substrate positioning subsystem, and a controller configured for causing the height sensor to measure the height (h) of the substrate surface at locations across the substrate. The measured heights are used to control the focusing of one or more patterns applied to the substrate. The height h is measured relative to a reference height (zref). The height sensor is operable to vary the reference height (zref), which allows a wider effective range of operation. Specifications for control of the substrate height during measurement can be relaxed. The reference height can be varied by moving one or more optical elements (566, 572, 576, 504 and/or 512) within the height sensor, or moving the height sensor. An embodiment without moving parts includes a multi-element photodetector (1212).

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: A level sensor to determine a height level of a substrate, that includes a projection unit including a projection grating having a period P, the projection grating configured to provide a patterned measurement beam, to the substrate, having a periodically varying intensity distribution in a first direction having the period P; a detection unit to receive a reflected patterned measurement beam after reflection on the substrate, the reflected patterned measurement beam having a periodically varying intensity distribution in a second direction, having the period P, wherein the detection unit has a sensor array to receive the reflected patterned measurement beam, the sensor array including a plurality of sensing elements arranged along the second direction at a pitch p smaller than or equal to half the period P, and a processing unit to determine the height level of the substrate based on a signal from the sensor.

Abstract: A level sensor to determine a height level of a substrate, that includes a projection unit including a projection grating having a period P, the projection grating configured to provide a patterned measurement beam, to the substrate, having a periodically varying intensity distribution in a first direction having the period P; a detection unit to receive a reflected patterned measurement beam after reflection on the substrate, the reflected patterned measurement beam having a periodically varying intensity distribution in a second direction, having the period P, wherein the detection unit has a sensor array to receive the reflected patterned measurement beam, the sensor array including a plurality of sensing elements arranged along the second direction at a pitch p smaller than or equal to half the period P, and a processing unit to determine the height level of the substrate based on a signal from the sensor.