Asml Netherlands B.v.

Cymer, Inc.

Matthew Graham

Steven Chang

Wayne J Dunstan

Alexander Igorevich Ershov

William N Partlo

Robert A Bergstedt

Daniel Jason Riggs

David Robert Evans

James H Crouch

Paul Frihauf

Andrew Liu

Charles E Kinney

Jeroen Van Der Burgt

Igor Vladimirovich Fomenkov

Richard L Sandstrom

Robert Jay Rafac

Daniel J W Brown

Robert N Jacques

Kevin M O'Brien

Joshua Jon Thornes

Robert P Akins

Alexander Anthony Schafgans

Andrei Dorobantu

David L Evans

Olav Haugan

Kevin Weimin Zhang

Spencer Rich

Jim Crouch

Patrick L Nelissen

Sean W McGrogan

Disclosed is an apparatus and a method in which off-droplet measurements instead of on-droplet measurements of prepulse energy are used for pulse energy control. Prepulse energy is measured during an off-droplet nonexposure period and controlled to a prepulse energy setpoint. The prepulse energy can then be controlled open-loop to the prepulse energy setpoint during on-droplet periods. This effectively decouples the EUV dose control loop from the prepulse energy control loop and avoids negative side effects of coupling such loops, for example, loss of the part of the dose adjustment range available to the dose controller.

Laser system for source material conditioning in an EUV light source

A device and method are disclosed in which a source material delivery system can be reoriented so that the path of the source material is not directly towards an irradiation region in operating conditions in which the path is expected to be unpredictable. A shroud provided to protect the flow of source material from being disrupted is segmented so with one part of the shroud being movable with respect to another part of the shroud so that the movable part can avoid interfering with the path of the source material when it is not directly towards the irradiation region.

Apparatus for and method of source material delivery in a laser produced plasma EUV light source

An optical lithography system is monitored. Information is received from the optical lithography system; a rule is accessed, the rule being associated with one or more of an event in the optical lithography system and an amount of time; a module stored in a library of modules is identified based on the accessed rule; whether a particular condition exists in the optical lithography system is determined using the identified module and the information received from the optical lithography system; and if the particular condition exists, a command signal is generated based on one or more characteristics of the particular condition and provided to an optical source of the optical lithography system. The command signal is based on the determined particular condition, and the command signal is sufficient to change one or more operating parameters of the optical source.

Monitoring system for an optical lithography system

An extreme ultraviolet light system includes a steering system that steers and focuses an amplified light beam traveling along a propagation direction to a focal plane near a target location within an extreme ultraviolet light chamber, a detection system including at least one detector positioned to detect an image of a laser beam reflected from at least a portion of a target material within the chamber, a wavefront modification system in the path of the reflected laser beam and between the target location and the detection system, and a controller. The wavefront modification system is configured to modify the wavefront of the reflected laser beam as a function of a target focal plane position along the propagation direction. The controller includes logic for adjusting a location of the focal plane of the amplified light beam relative to the target material based on the detected image of the reflected laser beam.

Alignment of light source focus

A device and method are disclosed in which gas is caused to flow parallel to a flow of source material to form a gas shroud. The gas shroud may protect flow of source material from being disrupted by a cross flow of gas. The gas shroud may also limit heating of a physical shroud through which the source material passes and limit accumulation of source material on the physical shroud by deforming a plasma bubble formed during irradiation of the source material so that the plasma bubble does not come too near the physical shroud. A device and method are also disclosed for establishing an additional transverse flow of gas so that the gas shroud does not cause source material contamination of an optic used to collect light generated during irradiation of the source material.

A method and apparatus for control of a dose of extreme ultraviolet (EUV) radiation generated by a laser produced plasma (LPP) EUV light source that combines pulse control mode and pulse modulation. The EUV energy created by each pulse is measured and total EUV energy created by the fired pulses determined, a desired energy for the next pulse is determined based upon whether the total EUV energy is greater or less than a desired average EUV energy times the number of pulses. If the desired pulse energy for the next droplet is within the range of one or more pulse modulation actuators, the pulse is modulated; otherwise, the pulse is fired to miss the droplet. This provides greater control of the accumulated dose as well as uniformity of the EUV energy over time, greater ability to compensate for pulses that generate EUV energy that is higher or lower than nominal expected values, and ability to provide an average EUV energy per pulse that is less than the nominal minimum EUV energy per pulse of the system.

EUV LPP source with improved dose control by combining pulse modulation and pulse control mode

Energy output from a laser-produced plasma (LPP) extreme ultraviolet light (EUV) system varies based on how well the laser beam is focused on droplets of target material to generate plasma at a primary focal spot. Maintaining droplets at the primary focal spot during burst firing is difficult because generated plasma from preceding droplets push succeeding droplets out of the primary focal spot. Current droplet-to-droplet feedback control to re-align droplets to the primary focal spot is relatively slow. The system and method described herein adaptively pre-compensate for droplet push-out by directing droplets to a target position that is offset from the primary focal spot such that when a droplet is lased, the droplet is pushed by the laser beam into the primary focal spot to generate plasma. Over time, the EUV system learns to maintain real-time alignment of droplet position so plasma is generated consistently within the primary focal spot.

System and method to adaptively pre-compensate for target material push-out to optimize extreme ultraviolet light production

A droplet generation system for use with a laser produced plasma (LPP) extreme ultraviolet (EUV) source plasma chamber is described. During EUV generation, oscillations can occur as a function of droplet time-of-flight within the plasma chamber. To reduce these oscillations, a droplet controller adjusts the rate at which droplets are generated which, in turn, dictates the droplet time-of-flight. The droplets are a result of coalescence of generated microdroplets such that the rate at which the droplets are generated is dictated by a frequency of a signal used to generate the microdroplets. This adjustment can be a modulation of a baseline droplet frequency. In some instances, the modulation function may be a sinusoid or implemented as a pseudo-random switch.

System and method to reduce oscillations in extreme ultraviolet light generation

Extreme ultraviolet light (EUV) is produced in a laser-produced plasma (LPP) EUV light source when laser light strikes a target. Measuring reflected light from the target by a Return Beam Diagnostics (RBD) module provides data on EUV production, including but not limited to target position, target focus, target shape, and target profile. In a RBD module, a controller sequences an optical switch to direct the reflected light between a blocking element and a sensing device, providing greater flexibility in measuring the reflected light during different aspects of the EUV generation process, such as different power levels and duty cycles of the laser light striking the target.

System and method for return beam metrology with optical switch

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.

System and method for adjusting seed laser pulse width to control EUV output energy

An apparatus includes a drive laser system producing an amplified light beam of pulses that travels along a drive axis; a beam delivery system that directs the amplified light beam of pulses toward a target region; a target material delivery system that provides a target mixture containing a target material in the target region; two or more sensors radially separated from a main axis that crosses the target region, the two or more sensors being configured to detect energy of ultraviolet electromagnetic radiation emitted from a plasma state of the target material when the amplified light beam of pulses intersects the target mixture; and a controller that receives the output from the two or more sensors. The controller is configured to estimate a relative radial alignment between the target mixture and the drive axis within the target region based on an analysis of the detected energy.

Energy sensors for light beam alignment

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.

Growing community of inventors

San Diego, CA, United States of America

Matthew Graham