Abstract: A radioisotope production apparatus comprising an electron source arranged to provide an electron beam. The electron source comprises an electron injector and an electron accelerator. The radioisotope production apparatus further comprises a target support structure configured to hold a target and a beam splitter arranged to direct the a first portion of the electron beam along a first path towards a first side of the target and to direct a second portion of the electron beam along a second path towards a second side of the target.

Abstract: A radioisotope production apparatus (RI) comprising an electron source arranged to provide an electron beam (E). The electron source comprises an electron injector (10) and an electron accelerator (20). The radioisotope production apparatus (RI) further comprises a target support structure configured to hold a target (30) and a beam splitter (40) arranged to direct the a first portion of the electron beam along a first path towards a first side of the target (30) and to direct a second portion of the electron beam along a second path towards a second side of the target (30).

Abstract: An apparatus for determining information relating to at least one target alignment mark in a semiconductor device substrate. The target alignment mark is initially at least partially obscured by an opaque carbon or metal layer on the substrate. The apparatus includes an energy delivery system configured to emit a laser beam for modifying at least one portion of the opaque layer to cause a phase change and/or chemical change in the at least one portion that increases the transparency of the portion. An optical signal can propagate through the modified portion to determine information relating to the target alignment mark.

Abstract: A method of patterning lithographic substrates, the method including using a free electron laser to generate EUV radiation and delivering the EUV radiation to a lithographic apparatus which projects the EUV radiation onto lithographic substrates, wherein the method further includes reducing fluctuations in the power of EUV radiation delivered to the lithographic substrates by using a feedback-based control loop to monitor the free electron laser and adjust operation of the free electron laser accordingly.

Abstract: A delivery system for use within a lithographic system. The beam delivery system comprises optical elements arranged to receive a radiation beam from a radiation source and to reflect portions of radiation along one or more directions to form a one or more branch radiation beams for provision to one or more tools.

Abstract: An electron source, e.g. for a free electron laser used for EUV lithography comprises: • a cathode (203) configured to be connected to a negative potential (100, 101); • a laser (110) configured to direct pulses of radiation onto the cathode so as to cause the cathode to emit bunches of electrons; • an RF booster (180) connected to an RF source and configured to accelerate the bunches of electrons; and • a timing corrector (303, 313, 400, 401) configured to correct the time of arrival of bunches of electrons at the RF booster relative to the RF voltage provided by the RF source. The timing corrector may comprise a correction electrode (303, 313) surrounding a path of the bunches of electrons from the cathode to the RF booster and a correction voltage source (400, 401) configured to apply a correction voltage to the correction electrode.

Abstract: A method of patterning lithographic substrates, the method comprising using a free electron laser to generate EUV radiation and delivering the EUV radiation to a lithographic apparatus which projects the EUV radiation onto lithographic substrates, wherein the method further comprises reducing fluctuations in the power of EUV radiation delivered to the lithographic substrates by using a feedback-based control loop to monitor the free electron laser and adjust operation of the free electron laser accordingly.

Abstract: A method of patterning lithographic substrates, the method including using a free electron laser to generate EUV radiation and delivering the EUV radiation to a lithographic apparatus which projects the EUV radiation onto lithographic substrates, wherein the method further includes reducing fluctuations in the power of EUV radiation delivered to the lithographic substrates by using a feedback-based control loop to monitor the free electron laser and adjust operation of the free electron laser accordingly.

Abstract: A membrane transmissive to EUV radiation, which may be used as a pellicle or spectral filter in a lithographic apparatus. The membrane includes one or more high doped regions wherein the membrane is doped with a dopant concentration greater than 1017 cm?3, and one or more regions with low (or no) doping. The membrane may have a main substrate having low doping and one or more additional layers, wherein the high doped regions are comprised within some or all of the additional layers.

Abstract: A radioisotope production apparatus (RI) comprising an electron source arranged to provide an electron beam (E). The electron source comprises an electron injector (10) and an electron accelerator (20). The radioisotope production apparatus (RI) further comprises a target support structure configured to hold a target (30) and a beam splitter (40) arranged to direct the a first portion of the electron beam along a first path towards a first side of the target (30) and to direct a second portion of the electron beam along a second path towards a second side of the target (30).

Abstract: An electron source, e.g. for a free electron laser used for EUV lithography comprises: a cathode (203) configured to be connected to a negative potential (100, 101); a laser (110) configured to direct pulses of radiation onto the cathode so as to cause the cathode to emit bunches of electrons; an RF booster (180) connected to an RF source and configured to accelerate the bunches of electrons; and a timing corrector (303, 313, 400, 401) configured to correct the time of arrival of bunches of electrons at the RF booster relative to the RF voltage provided by the RF source. The timing corrector may comprise a correction electrode (303, 313) surrounding a path of the bunches of electrons from the cathode to the RF booster and a correction voltage source (400, 401) configured to apply a correction voltage to the correction electrode.

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: An undulator for a free electron laser includes a pipe for an electron beam and one or more periodic magnetic structures extending axially along the pipe. Each periodic magnetic structure includes a plurality of magnets and a plurality of passive ferromagnetic elements, the plurality of magnets being arranged alternately with the plurality of passive ferromagnetic elements in a line extending in an axial direction. Each of the plurality of magnets is spatially separated from the pipe, and each of the passive ferromagnetic elements extends radially from an adjacent magnet towards the pipe. A spacer element may be provided between the magnets and the pipe to provide radiation shielding for the magnets and/or cooling for the pipe.

Abstract: A method of patterning lithographic substrates, the method comprising using a free electron laser to generate EUV radiation and delivering the EUV radiation to a lithographic apparatus which projects the EUV radiation onto lithographic substrates, wherein the method further comprises reducing fluctuations in the power of EUV radiation delivered to the lithographic substrates by using a feedback-based control loop to monitor the free electron laser and adjust operation of the free electron laser accordingly.

Abstract: Passage through LINACs of electron bunches in their acceleration phase is coordinated with passage through the LINACs of electron bunches in their deceleration phase. Each successive pair of electron bunches are spaced in time by a respective bunch spacing, in accordance with a repeating electron bunch sequence. The electron source provides clearing gaps in the electron bunch sequence to allow clearing of ions at the undulator. The electron source provides the clearing gaps in accordance with a clearing gap sequence such that, for each of the plurality of energy recovery LINACS, and for substantially all of the clearing gaps: for each passage of the clearing gap through the LINAC in an acceleration phase or deceleration phase the clearing gap is coordinated with a further one of the clearing gaps passing through the LINAC in a deceleration phase or acceleration phase thereby to maintain energy recovery operation of the LINAC.

Abstract: A method of patterning lithographic substrates that includes using a free electron laser to generate EUV radiation and delivering the EUV radiation to a lithographic apparatus which projects the EUV radiation onto lithographic substrates. The method further includes reducing fluctuations in the power of EUV radiation delivered to the lithographic substrates by using a feedback-based control loop to monitor the free electron laser and adjust operation of the free electron laser accordingly, and applying variable attenuation to EUV radiation that has been output by the free electron laser in order to further control the power of EUV radiation delivered to the lithographic apparatus.

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: Passage through LINACs of electron bunches in their acceleration phase is coordinated with passage through the LINACs of electron bunches in their deceleration phase. Each successive pair of electron bunches are spaced in time by a respective bunch spacing, in accordance with a repeating electron bunch sequence. The electron source provides clearing gaps in the electron bunch sequence to allow clearing of ions at the undulator. The electron source provides the clearing gaps in accordance with a clearing gap sequence such that, for each of the plurality of energy recovery LINACS, and for substantially all of the clearing gaps: for each passage of the clearing gap through the LINAC in an acceleration phase or deceleration phase the clearing gap is coordinated with a further one of the clearing gaps passing through the LINAC in a deceleration phase or acceleration phase thereby to maintain energy recovery operation of the LINAC.

Abstract: An injector arrangement for providing an electron beam. The injector arrangement comprises a first injector for providing electron bunches, and a second injector for providing electrons bunches. The injector arrangement is operable in a first mode in which the electron beam comprises electron bunches provided by the first injector only and a second mode in which the electron beam comprises electron bunches provided by the second injector only.

Abstract: A membrane transmissive to EUV radiation, which may be used as a pellicle or spectral filter in a lithographic apparatus. The membrane includes one or more high doped regions wherein the membrane is doped with a dopant concentration greater than 1017 cm?3, and one or more regions with low (or no) doping. The membrane may have a main substrate having low doping and one or more additional layers, wherein the high doped regions are comprised within some or all of the additional layers.