Abstract: A radiation measurement system (200) comprising an optical apparatus (205) configured to receive a radiation beam (210) and change an intensity distribution of the radiation beam to output a conditioned radiation beam (215), and a spectrometer (220) operable to receive the conditioned radiation beam and determine spectral content of the conditioned radiation beam. The radiation measurement system may form part of a lithographic apparatus.

Abstract: A method includes: producing a light beam made up of pulses having a wavelength in the deep ultraviolet range, each pulse having a first temporal coherence defined by a first temporal coherence length and each pulse being defined by a pulse duration; for one or more pulses, modulating the optical phase over the pulse duration of the pulse to produce a modified pulse having a second temporal coherence defined by a second temporal coherence length that is less than the first temporal coherence length of the pulse; forming a light beam of pulses at least from the modified pulses; and directing the formed light beam of pulses toward a substrate within a lithography exposure apparatus.

Abstract: An apparatus (10) for increasing a pulse length of a pulsed radiation beam, the apparatus comprising: a beam splitter (16) configured to split an input radiation beam (18) into a first beam (24) and a second beam (22); an optical arrangement (12, 14), wherein the beam splitter and the optical arrangement are configured such that at least a portion of the first beam is recombined with the second beam into a modified beam after an optical delay of the first beam caused by the optical arrangement; and at least one optical element (30) in an optical path of the first beam, the at least one optical element configured such that the phase of different parts of a wavefront of the first beam is varied to reduce coherence between the first beam and the second beam.

Abstract: A control system for controlling a laser, comprising a sensor for sensing a physical value indicative of a characteristic of a laser beam emitted by the laser, a switch, a first controller and a second controller. Each controller is configured, to receive a further sensor value from the sensor, adjust a received setpoint value based on the received further sensor value to give an output value and cause the laser to operate in accordance with the output value. The switch is configured to switch between the controllers such that output values are provided from each controller in a cyclic fashion.

Abstract: An apparatus (10) for increasing a pulse length of a pulsed radiation beam, the apparatus comprising: a beam splitter (16) configured to split an input radiation beam (18) into a first beam (24) and a second beam (22); an optical arrangement (12,14), wherein the beam splitter and the optical arrangement are configured such that at least a portion of the first beam is recombined with the second beam into a modified beam after an optical delay of the first beam caused by the optical arrangement; and at least one optical element (30) in an optical path of the first beam, the at least one optical element configured such that the phase of different parts of a wavefront of the first beam is varied to reduce coherence between the first beam and the second beam.

Abstract: A method includes: producing a light beam made up of pulses having a wavelength in the deep ultraviolet range, each pulse having a first temporal coherence defined by a first temporal coherence length and each pulse being defined by a pulse duration; for one or more pulses, modulating the optical phase over the pulse duration of the pulse to produce a modified pulse having a second temporal coherence defined by a second temporal coherence length that is less than the first temporal coherence length of the pulse; forming a light beam of pulses at least from the modified pulses; and directing the formed light beam of pulses toward a substrate within a lithography exposure apparatus.

Abstract: A method includes: producing a light beam made up of pulses having a wavelength in the deep ultraviolet range, each pulse having a first temporal coherence defined by a first temporal coherence length and each pulse being defined by a pulse duration; for one or more pulses, modulating the optical phase over the pulse duration of the pulse to produce a modified pulse having a second temporal coherence defined by a second temporal coherence length that is less than the first temporal coherence length of the pulse; forming a light beam of pulses at least from the modified pulses; and directing the formed light beam of pulses toward a substrate within a lithography exposure apparatus.

Abstract: A method of controlling output of a radiation source, the method including: periodically monitoring an output energy of the radiation source; determining a difference between a reference energy signal and the monitored output energy; determining a feedback value; determining a desired output energy of the radiation source for a subsequent time period; and controlling an input parameter of the radiation source in dependence on the determined desired output energy during the subsequent time period. If the magnitude of the determined difference between the monitored output energy of the radiation source and the reference energy signal exceeds a threshold value: the determined difference does not contribute to the feedback value; and the determined difference is spread over the subsequent time period according to a reference energy signal adjustment profile and the reference energy signal adjustment profile is added to the reference energy signal for the subsequent time period.

Abstract: A method includes: producing a light beam made up of pulses having a wavelength in the deep ultraviolet range, each pulse having a first temporal coherence defined by a first temporal coherence length and each pulse being defined by a pulse duration; for one or more pulses, modulating the optical phase over the pulse duration of the pulse to produce a modified pulse having a second temporal coherence defined by a second temporal coherence length that is less than the first temporal coherence length of the pulse; forming a light beam of pulses at least from the modified pulses; and directing the formed light beam of pulses toward a substrate within a lithography exposure apparatus.

Abstract: A method includes: producing a light beam made up of pulses having a wavelength in the deep ultraviolet range, each pulse having a first temporal coherence defined by a first temporal coherence length and each pulse being defined by a pulse duration; for one or more pulses, modulating the optical phase over the pulse duration of the pulse to produce a modified pulse having a second temporal coherence defined by a second temporal coherence length that is less than the first temporal coherence length of the pulse; forming a light beam of pulses at least from the modified pulses; and directing the formed light beam of pulses toward a substrate within a lithography exposure apparatus.

Abstract: An illumination system for a lithographic apparatus includes an array of lenses configured to receive a radiation beam and focus the beam into a plurality of sub-beams, an array of reflective elements configured to receive the sub-beams and reflect the sub-beams so as to form an illumination beam, a beam splitting device configured to split the illumination beam into a first portion and a second portion wherein the first portion is directed to be incident on a lithographic patterning device, a focusing unit configured to focus the second portion of the illumination beam onto a detection plane such that an image is formed at the detection plane and wherein the image is an image of the sub-beams in which the sub-beams do not overlap with each other and an array of detector elements configured to measure the intensity of radiation which is incident on the detection plane.

Abstract: A technique involving projecting a pulsed radiation beam using an illumination system onto a region of a plane in a reference frame; using a scanning mechanism to move a calibration sensor relative to the reference frame such that the calibration sensor moves through the beam of radiation in the plane along a scan trajectory; determining a quantity indicative of a velocity of the illumination system relative to the reference frame; and determining information related to a spatial intensity distribution of the radiation beam in the plane in dependence on: (a) an output of the calibration sensor; (b) the scan trajectory of the calibration sensor; and (c) the quantity indicative of a velocity of the illumination system relative to the reference frame.

Abstract: A photocathode comprises a substrate in which a cavity is formed and a film of material disposed on the substrate. The film of material comprises an electron emitting surface configured to emit electrons when illuminated by a beam of radiation. The electron emitting surface is on an opposite side of the film of material from the cavity.

Abstract: A method of controlling output of a radiation source, the method including: periodically monitoring an output energy of the radiation source; determining a difference between a reference energy signal and the monitored output energy; determining a feedback value; determining a desired output energy of the radiation source for a subsequent time period; and controlling an input parameter of the radiation source in dependence on the determined desired output energy during the subsequent time period. If the magnitude of the determined difference between the monitored output energy of the radiation source and the reference energy signal exceeds a threshold value: the determined difference does not contribute to the feedback value; and the determined difference is spread over the subsequent time period according to a reference energy signal adjustment profile and the reference energy signal adjustment profile is added to the reference energy signal for the subsequent time period.

Abstract: A method includes: producing a light beam made up of pulses having a wavelength in the deep ultraviolet range, each pulse having a first temporal coherence defined by a first temporal coherence length and each pulse being defined by a pulse duration; for one or more pulses, modulating the optical phase over the pulse duration of the pulse to produce a modified pulse having a second temporal coherence defined by a second temporal coherence length that is less than the first temporal coherence length of the pulse; forming a light beam of pulses at least from the modified pulses; and directing the formed light beam of pulses toward a substrate within a lithography exposure apparatus.

Abstract: A technique involving projecting a pulsed radiation beam using an illumination system onto a region of a plane in a reference frame; using a scanning mechanism to move a calibration sensor relative to the reference frame such that the calibration sensor moves through the beam of radiation in the plane along a scan trajectory; determining a quantity indicative of a velocity of the illumination system relative to the reference frame; and determining information related to a spatial intensity distribution of the radiation beam in the plane in dependence on: (a) an output of the calibration sensor; (b) the scan trajectory of the calibration sensor; and (c) the quantity indicative of a velocity of the illumination system relative to the reference frame.

Abstract: A lithographic apparatus including: a radiation system; a frame; a substrate table for holding a substrate; and a scanning mechanism. The radiation system is operable to produce a radiation beam. The substrate table is moveably mounted to the frame and arranged such that a target portion of the substrate is arranged to receive the radiation beam. The scanning mechanism is operable to move the substrate table relative to the frame so that different portions of the substrate may receive the radiation beam. A mechanism is operable to determine a quantity indicative of a velocity of the radiation system relative to the frame. An adjustment mechanism is operable to control a power or irradiance of the radiation beam so as to reduce a variation in a dose of radiation received by the substrate as a result of relative motion of the radiation system and the frame.

Abstract: A lithographic apparatus including: a radiation system; a frame; a substrate table for holding a substrate; and a scanning mechanism. The radiation system is operable to produce a radiation beam. The substrate table is moveably mounted to the frame and arranged such that a target portion of the substrate is arranged to receive the radiation beam. The scanning mechanism is operable to move the substrate table relative to the frame so that different portions of the substrate may receive the radiation beam. A mechanism is operable to determine a quantity indicative of a velocity of the radiation system relative to the frame. An adjustment mechanism is operable to control a power or irradiance of the radiation beam so as to reduce a variation in a dose of radiation received by the substrate as a result of relative motion of the radiation system and the frame.

Abstract: An illumination system for a lithographic apparatus includes an array of lenses configured to receive a radiation beam and focus the beam into a plurality of sub-beams, an array of reflective elements configured to receive the sub-beams and reflect the sub-beams so as to form an illumination beam, a beam splitting device configured to split the illumination beam into a first portion and a second portion wherein the first portion is directed to be incident on a lithographic patterning device, a focusing unit configured to focus the second portion of the illumination beam onto a detection plane such that an image is formed at the detection plane and wherein the image is an image of the sub-beams in which the sub-beams do not overlap with each other and an array of detector elements configured to measure the intensity of radiation which is incident on the detection plane.

Abstract: A photocathode comprises a substrate in which a cavity is formed and a film of material disposed on the substrate. The film of material comprises an electron emitting surface configured to emit electrons when illuminated by a beam of radiation. The electron emitting surface is on an opposite side of the film of material from the cavity.