A radiation system comprises a fuel emitter configured to provide fuel to a plasma formation region, a laser arranged to provide a laser beam at the plasma formation region incident on the fuel to generate a radiation emitting plasma, and a reflective or transmissive device (30) arranged to receive radiation emitted by the plasma and to reflect or transmit at least some of the received radiation along a desired path, wherein the reflective or transmissive device comprises a body configured to reflect and/or transmit said at least some of the radiation, and selected secondary electron emission (SEE) material (34) arranged relative to the body such as to emit secondary electrons in response to the received radiation, thereby to clean material from a surface of the device.

32

In particular embodiments, the present disclosure provides targets including a metal layer and defining a hollow inner surface. The hollow inner surface has an internal apex. The distance between at least two opposing points of the internal apex is less than about 15 m. In particular examples, the distance is less than about 1 m. Particular implementations of the targets are free standing. The targets have a number of disclosed shaped, including cones, pyramids, hemispheres, and capped structures. The present disclosure also provides arrays of such targets. Also provided are methods of forming targets, such as the disclosed targets, using lithographic techniques, such as photolithographic techniques. In particular examples, a target mold is formed from a silicon wafer and then one or more sides of the mold are coated with a target material, such as one or more metals.

Capacitive measurements for monitoring vapor or deposits from a vapor in a radiation source for a lithography apparatus. The measurements may be used to control operation of the radiation source. In one particular arrangement measurements from a plurality of capacitors are used to distinguish between changes in capacitance caused by the vapor and changes in capacitance caused by deposits from the vapor.

An extreme ultraviolet (EUV) lithography system includes a collector designed to collect and reflect EUV radiation, a cover integrated with the collector, a first exhaust line connected to the cover and configured to receive debris vapor from the collector, a debris trapper connected to the first exhaust line and configured to trap the debris vapor, and a second exhaust line connected to the debris trapper.

An EUV light source serves for generating a usable output beam of EUV illumination light for a projection exposure apparatus for projection lithography. The light source has an EUV generation device which generates an EUV raw output beam. The latter is circularly polarized. For the purposes of setting the polarization of the usable output beam and in respect of the polarization direction, a polarization setting device has a linearly polarizing effect on the raw output beam. This results in an EUV light source, which provides an improved output beam for a resolution-optimized illumination.

There is provided a light source device according to one embodiment of the present disclosure for outputting an extreme ultraviolet light source based on an electron beam, comprising: a chamber; an electron beam emission unit including a cathode electrode and a plurality of emitters, each of which contains a carbon-based material and which are arranged over the cathode electrode in such a manner as to be spaced apart from each other, the electron beam emission unit generating an electron beam within the chamber; and an anode electrode positioned within the chamber, but in a manner that is spaced apart from the electron beam emission unit, and ionized upon incidence of the electron beam thereon, thereby generating plasma, wherein extreme ultraviolet is generated from the plasma.

An extreme ultraviolet generation device, including a chamber with an internal space; a plasma generator to generate plasma in the internal space; a condenser in the internal space to gather light generated from the plasma; and a monitor to monitor the internal space in an omnidirectional manner.

A differential phase contrast X-ray imaging system includes an X-ray illumination system, a beam splitter arranged in an optical path of the X-ray illumination system, and a detection system arranged in an optical path to detect X-rays after passing through the beam splitter.

A laser-sustained plasma light source for transverse plasma pumping includes a pump source configured to generate pumping illumination, one or more illumination optical elements and a gas containment structure configured to contain a volume of gas. The one or more illumination optical elements are configured to sustain a plasma within the volume of gas of the gas containment structure by directing pump illumination along a pump path to one or more focal spots within the volume of gas. The one or more collection optical elements are configured to collect broadband radiation emitted by the plasma along a collection path. Further, the illumination optical elements are configured to define the pump path such that pump illumination impinges the plasma along a direction transverse to a direction of propagation of the emitted broadband light of the collection path such that the pump illumination is substantially decoupled from the emitted broadband radiation.

A differential phase contrast X-ray imaging system includes an X-ray illumination system, a beam splitter arranged in an optical path of the X-ray illumination system, and a detection system arranged in an optical path to detect X-rays after passing through the beam splitter.