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.

Example implementations described herein include a laser source and associated methods of operation that can balance or reduce uneven beam profile problem and even improve plasma heating efficiency to enhance conversion efficiency and intensity for extreme ultraviolet radiation generation. The laser source described herein generates an auxiliary laser beam to augment a pre-pulse laser beam and/or a main-pulse laser beam, such that uneven beam profiles may be corrected and/or compensated. This may improve an intensity of the laser source and also improve an energy distribution from the laser source to a droplet of a target material, effective to increase an overall operating efficiency of the laser source.

An EUV light generation apparatus includes a chamber; a prepulse laser outputting prepulse laser light; a main pulse laser outputting main pulse laser light; a combiner combining optical paths of the prepulse laser light and the main pulse laser light; a light concentrating unit concentrating, on the target, the prepulse laser light and the main pulse laser light having the optical paths combined; a stage changing a position of the light concentrating unit; a first actuator changing a travel direction of the main pulse laser light; an EUV light sensor detecting EUV energy; a laser energy sensor detecting pulse energy of the main pulse laser light; and an EUV light generation control unit controlling the stage so that temporal variation of the EUV energy decreases and controlling the first actuator so that a ratio of the EUV energy to the pulse energy increases.

A system and a method for generating stable ultrashort pulses of XUV and soft X-ray radiation from laser-ablated plumes of a liquid target, using a laser source a pre-pulse and a laser source of a main pulse, by selecting the pre-pulse and the main pulse; directing and focusing the pre-pulse to a surface of the liquid target to ablate the surface of the liquid target, forming a plasma plume generating harmonics; the main pulse being selected for driving the harmonics.

A laser system for generating secondary radiation through interaction of a focused primary laser beam with a target material includes a laser beam source for providing a raw laser beam, and a beam guidance device for forming the focused primary laser beam from the raw laser beam. The focused primary laser beam is directed towards a target region in order to interact with the target material arranged in the target region. The beam guidance device includes a beam focusing device configured to form the primary laser beam by focusing a laser beam entering the beam focusing device, which corresponds to the raw laser beam. The beam focusing device includes at least two mirror elements spaced apart from one another. The beam focusing device has a numerical aperture between 0.001 and 0.01 provided that the primary laser beam propagates in a medium with a refractive index of less than 1.01.

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.

A method for operating a lithography apparatus is provided. The method includes using a laser generator, emitting a laser beam; using a radiation source, producing extreme ultraviolet radiation by hitting the target droplet by the laser beam; using a scanner, directing the EUV radiation onto a substrate through a mask; and performing an in-line inspection process on a target component in one of the laser generator, the radiation source, and the scanner when producing the EUV radiation.

Some implementations described herein provide a dual-feedback control system for laser beam targeting in a lithography system such as an EUV lithography system. In addition to using feedback from a high-frequency quad-cell sensor to adjust a target position of the pre-pulse laser beam based on a first portion of a phase of a wavefront of the pre-pulse laser beam, the dual-feedback control system uses feedback from a low-frequency camera sensor to adjust the target position of the pre-pulse laser beam based on a second portion of the phase of the wavefront.

An extreme ultraviolet light generation apparatus includes a first light source outputting first excitation light, a laser oscillator including an active medium and performing laser oscillation by irradiating the active medium with the first excitation light to output the laser light, a measurement instrument measuring a pulse energy and a pulse time width of the laser light, a temperature regulator that adjusts a temperature of a cooling medium that cools the first light source, and a processor. The processor controls the temperature regulator to adjust the temperature of the cooling medium so that the pulse energy measured by the measurement instrument falls within a target range of the pulse energy, and adjust a current value of a current supplied to the first light source so that the pulse time width measured by the measurement instrument falls within a target range of the pulse time width.

A method for generating secondary radiation includes providing a target material in a target region, and applying a pulse sequence comprising laser pulses to the target material in the target region. Interaction of the target material with the pulse sequence generates secondary radiation. The pulse sequence includes a prepulse and a main pulse trailing the prepulse. A pulse energy of the prepulse is between 2 J und 200 J. A pulse duration of the prepulse is between 200 fs and 5 ps. A pulse energy of the main pulse is between 2 mJ and 50 mJ. A pulse duration of the main pulse is between 15 fs and 300 fs. A pulse time interval between the prepulse and the main pulse is between 1 ps and 1 ns.