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.

A metrology system includes a light beam metrology apparatus configured to sense one or more aspects of an amplified light beam and to make adjustments to the amplified light beam based on the sensed one or more aspects; a target metrology apparatus configured to measure one or more properties of a modified target after a target has interacted with the amplified light beam, and to determine a moment when the modified target achieves a reference calibration state; and a control apparatus configured to: receive the reference calibration state and the moment at which the reference calibration state is achieved from the target metrology apparatus; determine a light beam calibration state of the amplified light beam based on the received reference calibration state and the moment at which the reference calibration state is achieved; and provide the light beam calibration state to the light beam metrology apparatus.

A target droplet source for an extreme ultraviolet (EUV) source includes a droplet generator configured to generate target droplets of a given material. The droplet generator includes a nozzle configured to supply the target droplets in a space enclosed by a chamber. In some embodiments, a nozzle tube is arranged within the nozzle of the droplet generator, and the nozzle tube includes a structured nozzle pattern configured to provide an angular momentum to the target droplets.

A collector mirror for an extreme ultraviolet (EUV) light generator includes a first mirror in a vessel, the vessel being configured to receive a material and a laser beam for generating the EUV light, a second mirror surrounding the first mirror, and a detachable third mirror between the first mirror and the second mirror, the third mirror having an inner diameter that is not smaller than an outer diameter of the first mirror, and an outer diameter that is not larger than an inner diameter of the second mirror.

A target substance replenishment device may include a first container containing a solid target substance, a first path through which the solid target substance supplied from the first container passes, a first supply switching device switching between a first state where supply of the solid target substance from the first container to the first path is suppressed and a second state where the supply of the solid target substance from the first container to the first path is allowed, a first valve connected to the first path, a second path which is connected to the first valve and through which the solid target substance having passed through the first valve passes, a first detector outputting a first detection signal indicating that the second path is clogged with the solid target substance, and a processor controlling the first supply switching device to the first state based on the first detection signal.

An optical source for a photolithography tool includes a source configured to emit a first beam of light and a second beam of light, the first beam of light having a first wavelength, and the second beam of light having a second wavelength, the first and second wavelengths being different; an amplifier configured to amplify the first beam of light and the second beam of light to produce, respectively, a first amplified light beam and a second amplified light beam; and an optical isolator between the source and the amplifier, the optical isolator including: a plurality of dichroic optical elements, and an optical modulator between two of the dichroic optical elements.

An extreme ultraviolet light (EUV) source apparatus includes a light source part for generating a plasma that emits EUV light; a first vacuum housing in which the light source part is located; a second vacuum housing arranged between the first vacuum housing and a utilizing apparatus in which the EUV light is utilized; and a debris trap located inside the second vacuum housing for deflecting debris particles emitted from the plasma, whereby the debris particles do not ingress into the utilizing apparatus. Between the first and second vacuum housings, there is provided a window through which the EUV light emitted from the light source part passes from the first vacuum housing to the second vacuum housing. A wall of the second vacuum housing has a through-hole and a window that is configured to allow the EUV light to pass from the second vacuum housing to the utilizing apparatus.

An extreme ultra violet (EUV) light source apparatus includes a metal droplet generator, a collector mirror, an excitation laser inlet port for receiving an excitation laser, a first mirror configured to reflect the excitation laser that passes through a zone of excitation, and a second mirror configured to reflect the excitation laser reflected by the first mirror.

An extreme ultraviolet (EUV) photolithography system detects debris travelling from an EUV generation chamber to a scanner. The photolithography system includes a detection light source and a sensor. The detection light source outputs a detection light across a path of travel of debris particles from the EUV generation chamber. The sensor senses debris particles by detecting interaction of the debris particles with the detection light.