Abstract: A method and apparatus for improved control of the trajectory and timing of droplets of target material in a laser produced plasma (LPP) extreme ultraviolet (EUV) light system is disclosed. A droplet illumination module generates two laser curtains for detecting the droplets. The first curtain is used for detecting the position of the droplets relative to a desired trajectory to the irradiation site so that the position of a droplet generator may be adjusted to direct the droplets to the irradiation site, as in the prior art. A droplet detection module detects each droplet as it passes through the second curtain, determines when the source laser should generate a pulse so that the pulse arrives at the irradiation site at the same time as the droplet, and sends a signal to the source laser to fire at the correct time.

Abstract: A method and apparatus for controlling the seed laser in a laser produced plasma (LPP) extreme ultraviolet (EUV) light system are disclosed. In one embodiment, a seed laser generates both pre-pulses and main pulses which are amplified and irradiate a target material. The widths of the main pulses are adjusted, for example by the use of an EOM or other optical switch, without adjusting the widths of the pre-pulses, to keep the EUV output energy at a desired level. Only if the main pulse widths are longer or shorter than a desired range is the duty cycle of the laser amplifier adjusted, to keep the main pulse widths in the desired range. Adjusting the main pulse widths in this way before adjusting the pump RF duty cycle allows for less adjustment of the duty cycle, thus causing less adjustment to the pre-pulses.

Abstract: A first temperature distribution that represents a temperature of an element adjacent to and distinct from a first optical element that is positioned to receive an amplified light beam is accessed. The accessed first temperature distribution is analyzed to determine a temperature metric associated with the element, the determined temperature metric is compared to a baseline temperature metric, and an adjustment to position of the amplified light beam relative to the first optical element is determined based on the comparison.

Abstract: Described herein are embodiments of a method to control energy dose output from a laser-produced plasma extreme ultraviolet light system by adjusting timing of fired laser beam pulses. During stroboscopic firing, pulses are timed to lase droplets until a dose target of EUV has been achieved. Once accumulated EUV reaches the dose target, pulses are timed so as to not lase droplets during the remainder of the packet, and thereby prevent additional EUV light generation during those portions of the packet. In a continuous burst mode, pulses are timed to irradiate droplets until accumulated burst error meets or exceeds a threshold burst error. If accumulated burst error meets or exceeds the threshold burst error, a next pulse is timed to not irradiate a next droplet. Thus, the embodiments described herein manipulate pulse timing to obtain a constant desired dose target that can more precisely match downstream dosing requirements.

Abstract: Described herein are embodiments of a method to control energy dose output from a laser-produced plasma extreme ultraviolet light system by adjusting timing of fired laser beam pulses. During stroboscopic firing, pulses are timed to lase droplets until a dose target of EUV has been achieved. Once accumulated EUV reaches the dose target, pulses are timed so as to not lase droplets during the remainder of the packet, and thereby prevent additional EUV light generation during those portions of the packet. In a continuous burst mode, pulses are timed to irradiate droplets until accumulated burst error meets or exceeds a threshold burst error. If accumulated burst error meets or exceeds the threshold burst error, a next pulse is timed to not irradiate a next droplet. Thus, the embodiments described herein manipulate pulse timing to obtain a constant desired dose target that can more precisely match downstream dosing requirements.

Abstract: Method of and apparatus for repairing an optical element disposed in a vacuum chamber while the optical element is in the vacuum chamber. An exposed surface of the optical element is exposed to an ion flux generated by an ion source to remove at least some areas of the surface that have been damaged by exposure to the environment within the vacuum chamber. The method and apparatus are especially applicable to repair multilayer mirrors serving as collectors in systems for generating EUV light for use in semiconductor photolithography.

Abstract: Optical element protection systems for protecting optical elements and particularly reflective optical elements from degradation of their optical properties in harsh environments such as the environment inside a vacuum chamber of an EUV light source. The systems include the uses of combinations of materials in various layers where the materials are chosen and the layers are configured and arranged to extend the lifetime of the optical element without compromising its optical properties.

Abstract: A dichroic beam splitter module is disclosed for separating a main pulse laser beam from a pre-pulse laser beam each traversing a common beam path. In one embodiment, two dichroic elements are physically aligned along the beam path and are configured to pass the pre-pulse, a laser light having a first wavelength, to target material located near an irradiation site yet reflect the main pulse, a laser light having a second wavelength. The reflected main pulse is then further reflected by two reflective elements or mirrors from the first dichroic element to the second dichroic element and then on to the irradiation site. In alternative embodiments, the first mirror is deformable to alter beam characteristics of the reflected main pulse beam and the second mirror is adjustable to align the main pulse beam to the irradiation site.

Abstract: Systems and methods for automatically performing a high accuracy gas inject in a laser chamber of a two chamber gas discharge laser such as an excimer laser are disclosed. A mathematical model relates the amount of halogen gas in the laser chamber after an inject to the amount of halogen gas present prior to the inject, the amount of halogen gas injected, and the consumption rate of halogen gas in the chamber. A fixed amount of halogen gas is added to the chamber in an initial number of injects to allow transients to settle out, after which the amount of halogen gas to be injected is that calculated to result in a desired amount of halogen gas after the inject according to the model. Measurements are taken after injects to update the actual amount of halogen gas present and the consumption rate of the halogen gas.

Abstract: A method and apparatus for stabilizing the seed laser in a laser produced plasma (LPP) extreme ultraviolet (EUV) light system are disclosed. In one embodiment, the cavity length of the laser may be adjusted by means of a movable mirror forming one end of the cavity. The time delay from the release of an output pulse to the lasing threshold next being reached is measured at different mirror positions, and a mirror position selected which results in a cavity mode being aligned with the gain peak of the laser, thus producing a minimum time delay from an output pulse of the laser to the next lasing threshold. A Q-switch in the laser allows for pre-lasing and thus jitter-free timing of output pulses. Feedback loops keep the laser output at maximum gain and efficiency, and the attenuation and timing at a desired operating point.

Abstract: An extreme ultraviolet light system and method includes a drive laser, a chamber including an extreme ultraviolet light collector and a target material dispenser including an adjustable target material outlet capable of outputting multiple portions of target material along a target material path. Also included: a drive laser steering device, a detection system including at least one detector and a controller coupled to the target material dispenser, the detector system and the drive laser steering device. The controller includes logic for detecting a location of the first portion of target material from the first light reflected from the first portion of target material and logic for adjusting the target material dispenser outlet to output a subsequent portion of target material to a waist of the focused drive laser. A system and a method for optimizing an extreme ultraviolet light output is also disclosed.

Abstract: Corrosion resistant electrodes are formed of brass that has been doped with phosphorus. The electrodes are formed of brass that contains about 100 ppm to about 1,000 ppm of phosphorus, and the brass has no visible microporosity at a magnification of 400×. The brass may be cartridge brass that contains about 30 weight percent of zinc and the balance copper. Corrosion resistant electrodes also may be formed by subjecting brass to severe plastic deformation to increase the resistance of the brass to plasma corrosion. The corrosion resistant electrodes can be used in laser systems to generate laser light.

Abstract: Energy output from a laser-produced plasma (LPP) extreme ultraviolet light (EUV) system varies based on how well the laser beam can maintain focus on a target material to generate the plasma that gives off light. The system and method described herein optimize EUV light generation by using a closed-loop gradient process to track and fine-tune in real-time the positioning of optical elements that determine how the laser beam is focused on the target material. When real-time alignment of the drive laser on droplet position is achieved, EUV generation is optimized.

Abstract: A method and apparatus for protecting the seed laser in a laser produced plasma (LPP) extreme ultraviolet (EUV) light system are disclosed in one embodiment, a Bragg AOM is used as a switch on the beam path from the seed laser to other optical components and ultimately to an irradiation site. Power is applied to the Bragg AOM and pulses from the seed laser are thus deflected onto the desired beam path rather than passing straight through the Bragg AOM. Once the pulses have passed through the Bragg AOM, power to the Bragg AOM ceases, so that any reflections from the irradiation site will pass straight through the Bragg AOM and will not be deflected back to the seed laser. Use of the Bragg AOM rather than components previously used results in lower power consumption and better protection for the seed laser.

Abstract: A dichroic beam splitter module is disclosed for separating a main pulse laser beam from a pre-pulse laser beam each traversing a common beam path. In one embodiment, two dichroic elements are physically aligned along the beam path and are configured to pass the pre-pulse, a laser light having a first wavelength, to target material located near an irradiation site yet reflect the main pulse, a laser light having a second wavelength. The reflected main pulse is then further reflected by two reflective elements or mirrors from the first dichroic element to the second dichroic element and then on to the irradiation site. In alternative embodiments, the first mirror is deformable to alter beam characteristics of the reflected main pulse beam and the second mirror is adjustable to align the main pulse beam to the irradiation site.

Abstract: Energy output from a laser-produced plasma (LPP) extreme ultraviolet light (EUV) system varies based on how well the laser beam can maintain focus on a target material to generate the plasma that gives off light. The system and method described herein optimize EUV light generation by using a closed-loop gradient process to track and fine-tune in real-time the positioning of optical elements that determine how the laser beam is focused on the target material. When real-time alignment of the drive laser on droplet position is achieved, EUV generation is optimized.

Abstract: A collector mirror of an extreme ultraviolet light source is cleaned by removing the collector mirror from a chamber of the extreme ultraviolet light source; mounting the collector mirror to a carrier; inserting the carrier with the collector mirror into a cleaning tank; applying a cleaning agent to a reflective surface of the collector mirror by spraying the cleaning agent through a plurality of nozzles directed toward the collector mirror reflective surface until the collector mirror reflective surface is clean; rinsing the applied cleaning agent from the collector mirror reflective surface; and drying the collector mirror reflective surface.

Abstract: A movable electrode assembly for use in a laser system, includes a first electrode having a first discharge surface, a second electrode having a second discharge surface. The second electrode being arranged opposite from the first electrode. The second discharge surface being spaced apart from the first discharge surface by a discharge gap. A discharge gap adjuster interfaced with at least one of the second electrode or the first electrode, the discharge gap adjuster configured to adjust the discharge gap. A method of adjusting a discharge gap is also disclosed.

Abstract: Devices are disclosed herein which may comprise a vessel; a material disposed in the vessel for creating an EUV light emitting plasma at a plasma site, the plasma generating debris; a near normal incidence EUV reflective optic disposed in the vessel; and a source of a magnetic field for deflecting debris in the vessel to protect the optic, the source positioned to interpose the optic between the source and the plasma site.

Abstract: A method and system for performing injects of halogen gas into the chambers of a two chamber gas discharge laser such as a MOPA excimer laser for allowing operation of the laser within acceptable parameters and compensating for ageing effects without the necessity of performing refills is described. A parameter reflecting efficiency of the laser is measured, and the change in the parameter with respect to the length of laser operation is estimated. The change in the parameter with respect to the pressure in one of the chambers is also measured. At a given time, the total change in the value of the parameter is estimated, and from this change in pressure that is needed to reverse the change in the value of the parameter is calculated. The pressure in the chamber is then changed to correct for the amount of time that the laser has been in operation.