An extreme ultraviolet light generator includes a collector including a first focus and a second focus, a droplet feeder configured to provide a source droplet toward the first focus of the collector, a laser generator configured to irradiate a laser toward the first focus of the collector, an airflow controller between the first focus and the second focus of the collector, the airflow controller having a ring shape, and the airflow controller including at least one slit, and a first part and a second part hinged to each other, and a control gas feeder configured to provide a control gas towards the at least one slit of the airflow controller.

A laser amplification device includes a laser oscillator that includes a first laser active medium including a mixed gas containing carbon dioxide gas and emits pulsed laser light with the full width at half maximum of between 15 ns to 200 ns, and a laser amplifier that includes a second laser active medium including a mixed gas containing carbon dioxide gas through which the pulsed laser light emitted from the laser oscillator passes to be shortened to pulsed laser light with the full width at half maximum of between 5 ns and 30 ns to be output.

A method includes ejecting initial droplets of a material using a nozzle. The method includes applying a pressure on the nozzle using an electromechanical element. The method includes controlling the applied pressure on the nozzle using an electrical signal generated by a waveform generator. The electrical signal includes a first periodic waveform and a second periodic waveform. The method includes coalescing the initial droplets to generate coalesced droplets based on the first and second periodic waveforms and drag. The method includes generating a detection signal, using a detector, corresponding to time intervals between crossings of coalesced droplets at the detector. The method includes determining at least first and second ones of the time intervals using a processor.

The stability of operations of an EUV light generating apparatus is improved. A droplet detector may include: a light source unit configured to emit illuminating light onto a droplet, which is output into a chamber and generate extreme ultraviolet light when irradiated with a laser beam; a light receiving unit configured to receive the illuminating light and to detect changes in light intensities; and a timing determining circuit configured to output a droplet detection signal that indicates that the droplet has been detected at a predetermined position within the chamber, based on a first timing at which the light intensity of the illuminating light decreases due to the droplet being irradiated therewith and a second timing at which the light intensity of the illuminating light increases.

A chamber device may include a chamber, and a target generation device assembled into the chamber and configured to supply a target material into the chamber, the target generation device including a tank configured to store the target material, a temperature variable device configured to vary temperature of the target material in the tank, and a nozzle section in which a nozzle hole configured to output the target material in a liquid form is formed, and the chamber device may further include a gas nozzle having an inlet port facing the nozzle section and configured to introduce gas into the chamber, a gas supply source configured to supply gas containing hydrogen to the gas nozzle to supply the gas containing the hydrogen to at least periphery of the nozzle section, and a moisture remover configured to remove moisture at least in the periphery of the nozzle section in the chamber.

A droplet accelerating assembly includes an acceleration chamber extending in a first direction parallel to an ejection direction of the droplet, the acceleration chamber having a first side connected to the droplet generator, a second side opposite the first side in the first direction, the second side including a discharge hole, and a fluid flow path, a pressure controller connected to the fluid flow path of the acceleration chamber, the pressure controller being configured to adjust an internal pressure of the acceleration chamber, an electrifier in the acceleration chamber, the electrifier being configured to electrify the droplet ejected by the droplet generator into an electrified droplet, and an accelerator in the acceleration chamber, the accelerator being configured to accelerate the electrified droplet.

A vessel (16) for an EUV radiation source, the vessel comprising a first opening (30) for accessing an interior (32) of the vessel, a first access member (34) configured to allow or prevent access to the interior of the vessel through the first opening, a second opening (36) for accessing the interior of the vessel, the second opening being arranged in the first access member and a second access member (38) arranged on the first access member and configured to allow or prevent access to the interior of the vessel through the second opening.

An apparatus for monitoring a stream of droplets of target material for generating a radiation beam in a radiation source, wherein the apparatus comprises: a target material emitter for creating the stream of droplets of target material, wherein the target material emitter comprises a chamber configured for the target material to pass through before forming the stream of droplets; a first transducer configured to generate acoustic pressures in the chamber, and a second transducer configured to sense the acoustic pressures in the chamber.

A circulation mechanism includes a storage section, a supply pipe, a collection pipe, a circulation drive section, and a protective member. The storage section accommodates liquid metal. The supply pipe supplies the liquid metal accommodated in the storage section to a target mechanism. The collection pipe is communicated with the storage section and collects the liquid metal that has been drained away from the target mechanism into the storage section. The circulation drive section allows the liquid metal accommodated in the storage section to move to the supply pipe, and thus circulates the liquid metal to and from the target mechanism. The protective member is disposed to cover a portion of an inner wall of the collection pipe, the portion corresponding to a position at which the liquid metal flowing through the collection pipe collides with the liquid metal accommodated in the storage section.

A light source for EUV radiation is provided. The light source includes a target droplet generator, a laser generator, and a controller. The target droplet generator is configured to provide target droplets to a source vessel. The laser generator is configured to provide a plurality of first laser pulses according to a control signal to irradiate the target droplets in the source vessel to generate plasma as the EUV radiation. The controller is configured to provide the control signal according to the temperature of the source vessel and droplet positions of the target droplets. When the temperature of the source vessel exceeds a temperature threshold value and a standard deviation of the droplet positions of the target droplets exceeds a first standard deviation threshold value, the controller is configured to provide the control signal to the laser generator, so as to stop providing the first laser pulses.