Apparatus for and method of controlling formation of droplets used to generate EUV radiation. The droplet source includes a fluid exiting an nozzle and a sub-system having an electro-actuatable element producing a disturbance in the fluid. The droplet source produces a stream that breaks down into droplets that in turn coalesce into larger droplets as they progress towards the irradiation region. The electro-actuatable element is driven by a control signal having a sine wave component and a square wave component. Various parameters such as a phase difference between the sine wave component and the square wave component are measured and controlled to minimize the formation of noncoalesced satellite droplets in the stream.

A photolithography system utilizes tin droplets to generate extreme ultraviolet radiation for photolithography. The photolithography system irradiates the droplets with a laser. The droplets become energized and emit extreme ultraviolet radiation. A collector reflects the extreme ultraviolet radiation toward a photolithography target. The photolithography system reduces splashback of the tin droplets onto the receiver by generating a net electric charge within the droplets using a charge electrode and decelerating the droplets by applying an electric field with a counter electrode.

An extreme ultraviolet light generation system includes a pulse laser light sensor measuring a pulse energy of the main pulse laser light, a target detection sensor generating a passage signal of the droplet target for irradiation with the main pulse laser light, an EUV light sensor measuring a pulse energy of the extreme ultraviolet light, and a processor. The processor includes a neural network receiving log data of the pulse energy obtained from the pulse laser light sensor, log data of an irradiation pulse interval of the main pulse laser light, and log data of the pulse energy obtained from the EUV light sensor, and generating information enabling to identify which state it is in among a normal state, a state of droplet target combining failure, a state of abnormal variation of droplet target intervals, and a state of abnormal relative position between the irradiation position and the mist-like target.

A light source includes a rotatable drum to be coated with xenon ice and illuminated by a laser beam to produce a plasma. The drum may also be translatable. The light source further includes a confocal chromatic sensor to measure distances from the confocal chromatic sensor to the rotatable drum. The confocal chromatic sensor may include a sensor head to focus light onto the rotatable drum and to detect reflected light from the rotatable drum. The sensor head and the rotatable drum may be disposed within a vacuum chamber.

A method includes irradiating a target droplet in an extreme ultraviolet (EUV) light source of an extreme ultraviolet lithography tool with non-ionizing light from a droplet illumination module. The method further includes detecting light reflected and/or scattered by the target droplet, and performing particle image velocimetry, based on the detected light, to determine a velocity of the target droplet. The method also includes adjusting a time delay between a generation of the target droplet and a generation of an excitation laser beam based on the velocity of the target droplet.

A method includes irradiating a target droplet in an extreme ultraviolet (EUV) light source of an extreme ultraviolet lithography tool with non-ionizing light from a droplet illumination module. The method further includes detecting light reflected and/or scattered by the target droplet, and performing particle image velocimetry, based on the detected light, to determine a velocity of the target droplet. The method also includes adjusting a time delay between a generation of the target droplet and a generation of an excitation laser beam based on the velocity of the target droplet.

A method for generating an extreme ultraviolet (EUV) radiation includes simultaneously irradiating two or more target droplets with laser light in an EUV radiation source apparatus to produce EUV radiation and collecting and directing the EUV radiation produced from the two or more target droplet by an imaging mirror.

A light source apparatus according to the present disclosure includes: a target holding unit having a holding surface for holding a target material for generating light; and an acquisition unit configured to acquire state information of the holding surface, in which the holding surface includes a first region and a second region, a depth of the first region from a predetermined surface is greater than that of the second region, the target material is held in the first region when the amount of the target material is a first amount, the target material is held in the first region and the second region when the amount of the target material is a second amount greater than the first amount, and the acquisition unit acquires the amount of the target material based on a region in which the target material occupies the holding surface in the acquired state information.

An extreme ultraviolet light generation apparatus includes a droplet target generation device and a solid target replenishment device. The droplet target generation device includes a tank configured to melt a solid target substance to generate a liquid target substance, and a nozzle configured to continuously generate a droplet target from the liquid target substance in the tank and output the droplet target toward a plasma generation region to which pulse laser light is concentrated, and is configured to apply a velocity difference between a plurality of droplet targets including the droplet target so that the plurality of droplet targets coalesce. The solid target replenishment device is configured to replenish the tank with a one-time replenishment amount of the solid target substance such that the coalescence of the plurality of droplet targets is completed before the plurality of droplet targets reach the plasma generation region.

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.