Adaptable EUV radiation source

Abstract

A system for and method of controlling the characteristics a pulsed beam of EUV radiation, for example by controlling one or both of the spatial extent of a plasma generated at the primary focus of the collector optics to produce the EUV radiation or the size and / or shape of an aperture at the intermediate focus of the collector optics.

Description

ADAPTABLE EUV RADIATION SOURCECROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to US Application No. 63 / 678,816, filed August 2, 2024, titled ADAPTABLE EUV RADIATION SOURCE, which is incorporated herein by reference in its entirety.FIELD

[0002] The present disclosure relates to extreme ultraviolet radiation sources that produce radiation by generating a plasma from a source material.BACKGROUND

[0003] Extreme ultraviolet (“EUV”) radiation, for example, electromagnetic radiation having a wavelength of around 50 nm or less (also sometimes referred to as soft x-rays), and including radiation at a wavelength of about 13 nm, is used in photolithography processes to produce extremely small features in substrates, for example, silicon wafers.

[0004] Methods for generating EUV radiation include, but are not limited to, altering the physical state of a target or source material to a plasma state. The source material includes an element, for example, xenon, lithium, or tin, with an emission line in the EUV portion of the spectrum. In one such method, often termed laser-produced plasma (“LPP”), the required plasma is produced by irradiating a source material in the form of, for example, a droplet, stream, or cluster of source material, with a laser beam that can be referred to as a main or drive laser beam. For this process, the plasma is typically produced in a sealed vessel, for example, a vacuum chamber, and the resulting radiation is monitored using various types of metrology equipment.

[0005] CO2 amplifiers and lasers, which output an amplified light beam at a wavelength of about 10600 nm, can afford certain advantages as drive lasers for irradiating the source material in an LPP process. This may be especially true for certain source materials, for example, for materials containing tin. For example, one advantage is the ability to produce a relatively high conversion efficiency between the drive laser input power and the output EUV power. In some embodiments, the driver laser includes a solid-state laser. The solid-state laser, often operating in the near-infrared region (e.g., about 1 micrometer (pm) from Nd:YAG or Yb:AG, or about 2 pm from a thulium-doped laser), provides various thermal management and compact footprint, leading to a flexible and scalable EUV source. In some embodiments, the EUV source leverages a hybrid approach, combining a gaseous laser (e.g., the CO2 amplifier or the CO2 laser) and the solid-state laser. For example, the solid-state laser is used for “pre-pulses” and / or “rarefication pulses” to further optimize the target material state for a more efficient interaction with a subsequent gaseous laser “main pulses” and / or “rarefication pulses” to enhance the overall EUV conversion efficiency.

[0006] EUV radiation may be produced in a multi-step process in which a target, e.g., a droplet of source material, is hit on its way to an irradiation site by one or more pulses of conditioning radiation that prepare the target for ultimate phase conversion by the main laser pulse at the irradiation site. Conditioning in this context may include altering the shape of the droplet, e.g., flattening the droplet, or the distribution of the droplet, e.g., at least partially dispersing some of the droplet as a mist, or even causing a partial phase change of the material making up the droplet. For the purposes of this disclosure, these pulses which are preliminary to the main converting pulse are referred to as conditioning pulses and include at least one of pre-pulses, rarefication pulses, and pedestal pulses, regardless of whether produced by a main drive laser or another drive laser. The term “pulses” refers to all manner of radiation pulses, regardless of their purpose and regardless of whether produced by a primary drive laser or another laser or some other device capable of producing radiation pulses.

[0007] Also, as mentioned above, as a result of conditioning, the droplet of source material will undergo physical changes preliminary to the state conversion induced by the main heating pulse, including shape changes and mass distribution changes. Sometimes the mass of source material is referred to as a droplet before it is conditioned and as a target after it has been conditioned at least once. Herein, the term “droplet” will be used to refer to the mass of source material before any conditioning and the term “target” will be used to refer to the mass of source material both before and after conditioning so that a droplet is a type of target, unless the context indicates otherwise.

[0008] There can be one beam or multiple, e.g., three, laser beams interacting with one target. The interaction will have tunable temporal, spatial, and energy operational parameters associated with it. A recipe specifying such parameters for the beam may include beam tunable operational parameters such as pulse energy, pulse duration, pulse alignment with the target, beam size, e.g., diameter, timing between multiple pulses, and pulse shape. A recipe specifying such parameters for the target may also include specification of target parameters such as the target size (e.g., diameter for a spherical target) and target velocity.

[0009] In other words, the characteristics of the EUV radiation that is produced by the interaction of one or more laser pulses and a target depends upon the characteristics of the laser pulses, that is, their number, energy, relative timing, laser beam cross sectional radius, and so on. The characteristics of the EUV radiation also depend on characteristics of the target including droplet size and velocity. Also, the characteristics of the EUV radiation depend on the nature of the interaction of the laser pulse(s) and the target, for example, whether one or more of the laser pulse strikes the target dead center or strikes the droplet off center.

[0010] In general, conventional EUV sources have been based on a throughput-preferred approach in which the amount of EUV radiation generated, and so the amount of EUV radiation that is available for lithography in the scanner, is maximized. In other words, EUV source architectures have traditionally been designed to maximize the EUV power “through-IF”, that is, thorough the collector intermediate focus. Pursuant to this approach an EUV source is operated in a single mode, with one plasma recipe,designed to provide stable EUV and high throughput. The throughput-preferred approach is typically implemented even in circumstances in which better beam quality would be more desirable than increased EUV output. Thus, in the past, there has been a tradeoff between imaging performance, that is, optical quality of the beam that dictates the fidelity with which the beam replicates the mask pattern on the wafer, and throughput performance, that is, the rate at which the beam can replicate the mask pattern on the wafer.

[0011] Also, in the past, there was a coupling between the target size and the energy of the EUV pulse produced by converting the target. It is potentially advantageous to break this coupling of size and energy and to be able to change the pulse energy without changing the size of the droplet.

[0012] It is in this context that the need for the presently disclosed subject matter arises.SUMMARY

[0013] The following presents a succinct summary of one or more embodiments in order to provide a basic understanding of the embodiments. This summary is not an extensive overview of all contemplated embodiments and is not intended to identify as key or critical any elements of the embodiments nor delineate the scope of any or all embodiments. Its sole purpose is to present some concepts of one or more embodiments in a streamlined form as a prelude to the more detailed description that is presented later.

[0014] According to an aspect of an embodiment there is disclosed a multimode extreme ultraviolet (EUV) radiation source comprising at least one drive laser adapted to produce EUV radiation by converting a target into a plasma, a memory for storing a first plasma recipe and a second plasma recipe, the first plasma recipe including a first set of specifications for generating a plasma according to a first priority and the second plasma recipe including a second set of specifications for generating a plasma according to a second priority, and a controller arranged to receive a selected one of the first plasma recipe and the second plasma recipe, and adapted to control the at least one drive laser in accordance with the first set of specifications if the first plasma recipe is the selected one of the first plasma recipe and the second plasma recipe and in accordance with the second set of specifications if the second plasma recipe is the selected one of the first plasma recipe and the second plasma recipe.

[0015] The first plasma recipe may include specifications for generating a plasma according to a first priority of wafer throughput and the second plasma recipe may include specifications for generating a plasma according to a second priority of image quality. The specifications may include the energy of a pulse of the drive laser radiation. The specifications may include a duration of a pulse of the drive laser radiation. The specifications may include a spatial distribution of the pulse of the drive laser radiation. The specifications may include a temporal distribution of the pulse of drive laser radiation.

[0016] The radiation source may further comprise at least one conditioning laser adapted to produce conditioning laser radiation to condition the target before being converted to a plasma by the drive laser radiation. The specifications may include the energy of a pulse of the conditioning laser radiation. Thespecifications may include a duration of a pulse of the conditioning laser radiation. The specifications may include a spatial distribution of the pulse of the conditioning laser radiation. The specifications may include a temporal distribution of the pulse of conditioning laser radiation.

[0017] The radiation source may further comprise a target generator adapted to produce at least one target comprising a droplet of source material that produces the extreme ultraviolet radiation after being converted to a plasma by the at least one drive laser and wherein the specifications may include one or more droplet specifications. The droplet specifications may include droplet size. The droplet specifications may include droplet coalescence.

[0018] The radiation source may further comprise a variable aperture placed in a beam path of the extreme ultraviolet radiation and wherein the specifications may include a shape or size of the variable aperture.

[0019] According to another aspect of an embodiment there is disclosed a method of using an extreme ultraviolet (EUV) source to provide EUV radiation to a wafer, the method comprising determining one or more metrics of the EUV radiation to be delivered to the wafer, the one or more metrics resulting from prioritizing imaging performance or from prioritizing throughput, selecting, from plasma recipes, a selected plasma recipe based on the one or more metrics, and controlling the EUV source to generate the plasma based on the selected plasma recipe.

[0020] The plasma recipe may be selected based on a pupil pattern. The plasma recipe may include a plasma size. The one or more metrics of the EUV radiation may include an edge placement error.

[0021] According to another aspect of an embodiment there is disclosed a method of operating an extreme ultraviolet (EUV) radiation source comprising producing drive laser radiation by converting a target into a plasma, selecting one of a first plasma recipe and a second plasma recipe, the first plasma recipe including a first set of specifications for generating a plasma according to a first priority and the second plasma recipe including a second set of specifications for generating a plasma according to a second priority, and controlling the drive laser radiation in accordance with the first set of specifications if the first plasma recipe is the selected one of the first plasma recipe and the second plasma recipe and in accordance with the second set of specifications if the second plasma recipe is the selected one of the first plasma recipe and the second plasma recipe.

[0022] The first plasma recipe may include specifications for generating a plasma according to a first priority of wafer throughput and the second plasma recipe may include specifications for generating a plasma according to a second priority of image quality. The specifications may include the energy of a pulse of the drive laser radiation. The specifications may include a duration of a pulse of the drive laser radiation. The specifications may include a spatial distribution of a pulse of the drive laser radiation. The specifications may include a temporal distribution of a pulse of the drive laser radiation.

[0023] The method may further comprise producing conditioning laser radiation to condition the target before being converted to a plasma by the drive laser radiation. The specifications may include the energy a pulse of the conditioning laser radiation. The specifications may include a duration of a pulseof the conditioning laser radiation. The specifications may include a spatial distribution of the conditioning laser radiation. The specifications may include a temporal distribution of the conditioning laser radiation.

[0024] The method may further comprise producing at least one target comprising a droplet of source material that produces the extreme ultraviolet radiation after being converted to a plasma by the at least one drive laser and wherein the specifications may include one or more droplet specifications. The droplet specifications may include droplet size. The droplet specifications may include droplet coalescence.

[0025] The method may further comprise a controlling variable aperture placed in a beam path of the extreme ultraviolet radiation and the specifications may include a shape or size of the variable aperture.

[0026] According to another aspect of an embodiment there is disclosed a multimode extreme ultraviolet (EUV) radiation source comprising a photolithography exposure system including a photolithography exposure system controller adapted to cause the photolithography exposure system to operate in a specified mode, a laser radiation source adapted to produce pulses of laser radiation and including a laser radiation source controller adapted to control at least one of pulse energy, pulse duration, pulse spatial distribution, and pulse temporal distribution of the pulses of laser radiation, and a plasma production recipe library containing a plurality of plasma production recipes specifying at least one of pulse energy, pulse duration, pulse spatial distribution, and pulse temporal distribution of the pulses of laser radiation. The photolithography exposure system controller is further adapted to supply an indication of the specified mode to the laser radiation source controller and the laser radiation source controller is further adapted to select a selected one of the plurality of plasma production recipes based the indication of the specified mode and control operation of the laser radiation in accordance with the selected one of the plurality of plasma production recipes.

[0027] Further embodiments, features, and advantages of the subject matter of the present disclosure, as well as the structure and operation of the various embodiments, are described in detail below with reference to the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWING

[0028] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate the disclosed subject matter and, together with the description, further serve to explain the principles of the disclosed subject matter and to enable a person skilled in the relevant art(s) to make and use the disclosed subject matter. The drawings are not to scale unless otherwise indicated.

[0029] FIG. 1 is a partially schematic functional block diagram of an overall broad conception for an LPP EUV radiation source system according to an aspect of an embodiment

[0030] FIG. 2 is a partially schematic functional block diagram of a drive laser pulse delivery system such as might be used in the arrangement of FIG. 1.

[0031] FIG. 3 is a partially schematic functional block diagram of a another pulse delivery system suchas might be used in the arrangement of FIG. 1.

[0032] FIG. 4 is a partially schematic functional block diagram of a another pulse delivery system such as might be used in the arrangement of FIG. 1.

[0033] FIG. 5 is a cutaway view of a nozzle assembly for a droplet generator such as might be used in the arrangement of FIG. 1.

[0034] FIG. 6 is a flow chart showing a mode of operation of a multi-mode radiation source according to an aspect of an embodiment.

[0035] FIG. 7 is a flow chart showing a manner of operation of a multi-mode radiation source according to an aspect of an embodiment.

[0036] FIG. 8 is a diagram of a cross section of energy distributions in a plasma according to an aspect of an embodiment.

[0037] FIG. 9 is a diagram of a cross section of energy distributions in a plasma according to an aspect of an embodiment.

[0038] FIG. 10 is a partially schematic diagram of a radiation source including a variable aperture according to an aspect of an embodiment.

[0039] FIGS . 11 A and 1 IB are a plan view and a cut away side view, respectively, of a variable aperture shutter according to an aspect of embodiment.

[0040] FIG. 12 is a functional block diagram of a multi-mode radiation source according to an aspect of an embodiment.

[0041] FIG. 13 is a functional block diagram of a photolithography system according to an aspect of an embodiment.

[0042] FIG. 14 is a functional block diagram of an overall control system for a multi-mode radiation source according to an aspect of an embodiment.

[0043] Further features and advantages of the presently disclosed subject matter, as well as the structure and operation of various embodiments of the presently disclosed subject matter, are described in detail below with reference to the accompanying drawings. It is noted that the scope of the presently disclosed subject matter is not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only. Additional embodiments will be apparent to persons skilled in the relevant art based on the teachings made available herein.DETAILED DESCRIPTION

[0044] Various embodiments are now described with reference to the drawings. In the following description, for purposes of explanation, numerous specific details are set forth in order to promote a thorough understanding of one or more embodiments. It may be evident in some or all instances, however, that any embodiment described below can be practiced without adopting the specific design details attributed to it below. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate description of one or more embodiments.

[0045] Before describing such embodiments in more detail, however, it is useful to present an example of an environment in which embodiments may be implemented. In the description that follows and in the claims the terms “up,” “down,” “top,” “bottom,” “vertical,” “horizontal,” and like terms may be employed. These terms are intended to show relative orientation only and not any orientation with respect to gravity unless otherwise indicated or clear from context.

[0046] With initial reference to FIG. 1 there is shown a schematic view of an exemplary EUV radiation source, e.g., a laser produced plasma EUV radiation source 10 according to one aspect of an embodiment. As shown, the EUV radiation source 10 may include a pulsed or continuous drive laser source 22, which may for example be a pulsed laser source producing a beam 12 of radiation at from about 1pm to about 10.6 pm. The pulsed laser source may have DC or RF excitation operating at high power and at a high pulse repetition rate. In some embodiments, the drive laser source 22 includes a gaseous laser (e.g., a gas discharge CO2 laser), a solid-state laser (e.g., aNd:YAG laser, aYb:YAG laser, and a thulium -doped laser), or a combination thereof.

[0047] The EUV radiation source 10 also includes a target material delivery system 24 for delivering target material in the form of liquid droplets or a continuous liquid stream. In this example, the target material is a liquid, but it could also be a solid or gas. The target material may be made up of tin or a tin compound, although other materials could be used. In the system depicted the target material delivery system 24 introduces droplets 14 of the target material into the interior of a vacuum chamber 26 having walls 27 to an irradiation region 28 where the target material may be irradiated to produce plasma. The vacuum chamber 26 may be provided with a liner 29. It should be noted that as used herein an irradiation region is a region where source material irradiation may or is intended to occur, and is an irradiation region even at times when no irradiation is actually occurring. The EUV light source may also include a beam steering system 32.

[0048] In the system shown, the components are arranged so that the droplets 14 travel substantially horizontally. The direction from the laser source 22 towards the irradiation region 28, that is, the nominal direction of propagation of the beam 12, may be taken as the Z axis. The path the droplets 14 take from the target material delivery system 24 to the irradiation region 28 may be taken as the X axis. The view of FIG. 1 is thus normal to the XZ plane. While a system in which the droplets 14 travel substantially horizontally is depicted, it will be understood by one having ordinary skill in the art the other arrangements can be used in which the droplets travel vertically or at some angle with respect to gravity between and including 90° (horizontal) and 0° (vertical).

[0049] The EUV radiation source 10 may also include an EUV light source controller system 60, a laser firing control system 65, along with the beam steering system 32. The EUV radiation source 10 may also include a detector such as a target position detection system which may include one or more droplet imagers 70 that generate an output indicative of an absolute position of a target or a relative position of a target, e.g., relative to the irradiation region 28, and provide this output to a target position detection feedback system 62 as a target error signal.

[0050] As shown in FIG. 1 , the target material delivery system 24 may include a target delivery control system 90. The target delivery control system 90 is operable in response to a signal, for example, the target error described above, or some quantity derived from the target error provided by the system controller 60, to adjust paths of the droplets 14 through the irradiation region 28. This may be accomplished, for example, by repositioning the point at which a target delivery mechanism 92 releases the droplets 14. The droplet release point may be repositioned, for example, by tilting the target delivery mechanism 92 or by laterally translating the target delivery mechanism 92. The target delivery mechanism 92 extends into the chamber 26 and is externally supplied with target material and with gas from a gas source (not shown) to place the target material in the target delivery mechanism 92 under pressure. The system also includes a target material receptacle 96 that catches unused droplets of target material, that is, droplets of target material that have not been converted.

[0051] Continuing with FIG. 1, the radiation source 10 may also include one or more optical elements. In the following discussion, a collector 30 is used as an example of such an optical element, but the discussion applies to other optical elements as well. The collector 30 may be a normal incidence reflector, for example, implemented as an MLM with additional thin barrier layers, for example B4C, ZrC, SisN4or C, deposited at each interface to effectively block thermally-induced interlayer diffusion. Other substrate materials, such as aluminum (Al) or silicon (Si), can also be used. The collector 30 may be in the form of a prolate ellipsoid, with a central aperture to allow the laser radiation 12 to pass through and reach the irradiation region 28. The collector 30 may be, e.g., in the shape of an ellipsoid that has a first focus at the irradiation region 28 and a second focus at a so-called intermediate point 40 (also called the intermediate focus) where the EUV radiation may be output from the EUV radiation source 10 and input to, e.g., an integrated circuit lithography scanner 50 which uses the radiation, for example, to process a silicon wafer workpiece 52 in a known manner using a reticle or mask 54. The silicon wafer workpiece 52 is then additionally processed in a known manner to obtain an integrated circuit device. In some embodiments, the EUV radiation may be input to an inspection apparatus for detecting defects or measuring dimensions during the semiconductor manufacturing process.

[0052] FIG. 2 is a diagram, not to scale, of a portion of the EUV radiation source 10 showing the laser source 22, targets 14, the irradiation region 28, the chamber 26, the target delivery control system 90, and the target delivery mechanism 92. Elements such as the collector 30 shown in FIG. 1 are not shown in FIG. 2 in order to promote clarity. The arrangement of FIG. 2 also includes a controller 100 combining, for example, the functions of the light source controller 60, target position detection feedback system 62, and the laser firing control system 65 of FIG. 1. As can be seen, the laser source 22 produces a beam which strikes one of the droplets 14 in the irradiation region 28.

[0053] FIG. 2 shows an example of a system in which a single laser produces a main heating pulse and does not include provision for any preliminary pulses. As mentioned, in other systems preliminary pulses are used to condition the target before it is ultimately converted. FIG. 3 shows a system having an additional laser 23 that hits and conditions a target 14 before the target 14 reaches the irradiationregion 28. It is also possible to have arrangements in which a single laser produces both the conditioning pulse and the main heating pulse. Such a system is shown in FIG. 4 in which an optical switching element 25 in which it steers the beam from the laser source 22 to strike the target to condition the target and then steers the beam from the laser source 22 to the irradiation region 28 where the target is converted.

[0054] As mentioned, the characteristics of the resulting pulse of EUV radiation depend in part on the characteristics of the laser pulses used to condition and convert the targets 14. Also as mentioned, the characteristics of the resulting EV radiation also depend on the characteristics of the droplets as determined at least in part on how the droplets are generated and delivered to the irradiation region 28. FIG. 5 shows an example of a nozzle assembly 200 such as can be used in the target delivery mechanism 92. The nozzle assembly 200 includes a nozzle body 220 and a nozzle nut 210. A nozzle cavity 235 is positioned within the nozzle body 220. Molten source material is forced under pressure through the nozzle body 220 and through a capillary 230 and out the end of a nozzle 240. An electromechanical transducer 250 is mechanically coupled to the capillary 230. The electromechanical transducer 250 which may be, for example, a piezoelectric transducer (PZT), imposes a waveform on the stream of molten source material exiting the nozzle 240. Various droplet parameters such as droplet size, droplet velocity, droplet coalescence, and droplet spacing can be controlled by controlling the pressure within the nozzle assembly 200 and the vibration of the capillary 230.

[0055] As mentioned, traditional EUV sources are typically operated to optimize throughput rather than lithography imaging and contrast performance. Such EUV sources typically operate with a single plasma recipe to achieve one rate of throughput while meeting one requirement on imaging performance. This mode of operation, however, does not account for the fact that not all features on a wafer require the same level of imaging performance. This leads to circumstances in which throughput is compromised unnecessarily when the selected imaging performance for some portions of the wafer is in excess of what is required. Conversely it leads to circumstances in which imaging performance is compromised unnecessarily when the throughput requirements imposed for some portions of the wafer are in excess of what is required.

[0056] According to an aspect of an embodiment a radiation source may be configured to be able to switch among multiple plasma recipes devised for different balances of imaging performance and throughput performance. Thus, for example, one recipe might be devised to deliver maximized throughput, while another recipe would be devised to provide optimal imaging performance achieved by minimizing EUV source size and maximizing EUV far-field / imaging stability. Which recipes to use could vary depending on where in the wafer the pattern is being imprinted. For example, the edges of the patterns or patterns at the edges of wafers may in some circumstances require either greater or lesser fidelity and it may be desired to control the EUV radiation characteristics to minimize edge placement error.

[0057] As another example, an EUV radiation source could be operated in an imaging mode tailored to any one of several different pupil patterns and / or pupil fdl ratios, i.e., the percentage of the pupil that has light in it. The source could be triggered to operate in any one of a number of different imaging / throughput modes based on the pupil pattern the scanner is currently using. In this way, an EUV source could be optimized for a particular pupil pattern. Better imaging performance may be achieved, for example, by forming a relatively smaller, brighter, and more stable plasma. While a high throughput plasma recipe would focus on maximizing EUV photons through the intermediate focus, instead the EUV source size could be selected to minimize aperture clipping losses.

[0058] FIG. 6 is a flowchart illustrating a manner of operation of a system according to an aspect of an embodiment. In the example of FIG. 6 the source has two modes of operation, an imaging preferred mode and a throughput preferred mode. As shown in FIG. 6, the desired mode of operation for the source is selected in a step S100. This selection can be made by a user or the selection can be made automatically depending upon the existence of a predetermined condition. If in step SI 00 it is determined that an imaging preferred mode is the selected mode, then in a step SI 10 the source is operated according to an imaging preferred recipe. If, however, it is determined in step SI 00 that a throughput preferred mode has been selected, then in step S 120 the source is operated according to a throughput preferred recipe. It will be apparent to one of ordinary skill in the art that there can be more than two modes and that there can be modes in addition to an imaging preferred mode and a throughput preferred mode.

[0059] FIG. 7 is a flow chart illustrating details of operation of a multimode illumination system capable of performing in accordance with any one of a number of different plasma recipes. A plasma recipe is obtained or specified in a step S200. As mentioned, this plasma recipe can include instructions relating to the operation of a conditioning laser (e.g. pulse duration, energy, aiming, and timing), the operation of a main drive laser (e.g. pulse duration, energy, aiming, and timing), the target material dispenser (e.g., droplet size, position, velocity, and coalescence). Other parameters that would apply to both the conditioning laser and / or the main drive laser are parameters related to the spatial distribution or shape of the beam such as the magnitude of the beam radius and the beam energy as a function of time, i.e., the temporal distribution or shape of the beam, such as whether the beam energy as a function of time is Gaussian or has a temporal profile that exhibits a flat portion. The plasma recipe can also include instructions regarding the operation of an intermediate focus aperture shutter assembly as described in more detail below.

[0060] After the plasma recipe is obtained in step S200, it is determined what operational parameters the plasma recipe specifies. Thus, if it is determined in a step S210 that the plasma recipe includes instructions for one or more conditioning lasers, then, in a step S220 the conditioning laser is controlled according to the parameters specified in the plasma recipe. If, however, the plasma recipe does not include instructions relating to the conditioning lasers, then in step 230 the conditioning lasers are controlled according to default settings. Similarly, if it is determined in a step S250 that the plasmarecipe includes instructions for the main drive laser, then, in a step S260 the main drive laser is controlled according to the parameters specified in the plasma recipe. If, however, the plasma recipe does not include instructions relating to the main drive laser, then in step 270 the main drive laser is controlled according to default settings.

[0061] In a similar manner, if it is determined in a step S300 that the plasma recipe includes instructions for the target material dispenser, then, in a step S310 the target material dispenser is controlled according to the parameters specified in the plasma recipe. If, however, the plasma recipe does not include instructions relating to the target material dispenser, then in step 320 the conditioning lasers are controlled according to default settings. If it is determined in a step S350 that the plasma recipe includes instructions for operation of the IF aperture then the IF aperture is operated as required.

[0062] For example, one objective in selecting a plasma recipe may be to control the physical size of the plasma generated in the chamber. An application in which imaging quality is more critical than throughput rate may benefit from a smaller plasma while an application in which the opposite is true and throughput is more important a goal than imaging quality may benefit from a larger plasma. These two sizes of plasmas are depicted in FIGS. 8 and 9, in which FIG. 8 shows a typical, larger plasma which would be selected if increased throughput is the goal. FIG. 9, on the other hand, shows a smaller plasma which the source would be set up to generate if better imaging quality is the goal. In the figures, the outermost contour encloses 100 % of the beam energy, the innermost contour encompasses 10% of the beam energy, and the intermediate contour encompasses 90% of the beam energy.

[0063] According to an aspect of an embodiment one or more of the conditioning pulses such as the pre-pulse and rarefaction pulse could turned off completely in order to make a very small plasma. Intermediate cases exist, where an intermediate plasma size is selected that simultaneously delivers good imaging and good throughput (but not maximized throughput). Cases like this would be beneficial to lithography steps or printed features deemed more critical, where a customer might want to slow down throughput slightly in order to obtain higher quality printed features.

[0064] The characteristics of the beam of radiation generated by the source can also be set by using a variable IF aperture at the IF of the collector 30. This is depicted in FIG. 10 which shows an arrangement for a source having a variable IF aperture 300 positioned at the IF 40. FIGS. 11A and 11B show a possible configuration of the variable IF aperture 300 with FIG. 11A being a plan view and FIG. 11B being a cutaway view a long line BB of FIG. 11 A. As can be seen, the variable IF aperture 300 can be implemented as a plate with a linear array of apertures 310, 320, 330, 340, 350, and 360 of various sizes and shapes. The variable IF aperture 300 can be moved as indicated by the solid black arrow in FIG. 11B so that a selected one of the apertures is positioned so that the beam of radiation indicated by the open arrow in figure 11 B passes through it. In such arrangements the apparent spatial extent of plasma in the EUV light source would be physically limited by a reduction in the IF aperture size. For example, the largest aperture may have a size in the range of about 4 mm to about 10 mm and the smallest aperture may have a size in a range of about 1 mm to about 4mm. Which of the apertures 310, 320, 330, 340,350, and 360 is to be placed in the beam path can be determined using a motor arranged to move the variable IF aperture 300 as indicated by the solid black arrow. The motor can be operated under the control of a controller as described below.

[0065] Also, a EUV light source could be operated in a better imaging mode for different pupil patterns, or triggered to operate in a different imaging / throughput mode based on the pupil pattern the scanner was using. As is known in semiconductor photolithography, to achieve higher imaging fidelity at the wafer, it is desirable to use various pupil shapes such as dipole, annular, and quadrupole shapes that illuminate the reticle with larger angles of incidence. The use of these pupil shapes may entail the use of a smaller source size (produced, for example, either by generating a smaller plasma at the source primary focus or using a variable IF aperture that “clips” the source to the required size. Using a system as described above, the EUV source can be optimized for a particular pupil pattern.

[0066] FIG. 12 is a functional black diagram of a system 400 for operating a multimode EUV source to supply a pulsed beam of EUV radiation having variable characteristics by controlling one or both of the size of the plasma generated and the size of the aperture at intermediate focus through which the beam passes. As can be seen, the system 400 includes a system controller 410 which may be the same as or separate from other system controllers described herein. The system controller 410 includes a laser controller 420 which controls the operation of both the main drive laser 510 and one or more conditioning lasers 500 if present. The system controller 410 also includes a target material dispenser controller 430 for controlling a target material dispenser 520 and an IF aperture controller 440 for controlling a variable IF aperture 530 if present.

[0067] In use, the system controller 410 fetches a specified plasma recipe from a plasma recipe library 450. Alternatively, a plasma recipe can be input to the system controller 410 through a user interface 460. The recipes are conveyed to the system controller 410 by an input bus 480. The controllers within the system controller 410 then control the operation of the EUV source in accordance with the retrieved or input recipe. Thus, the laser controller 420 controls the conditioning lasers 500 and the drive laser 510 to produce a plasma of a desired size. The target material dispenser 430 controls the target material dispenser 520 to produce droplets having the desired characteristics. The IF aperture controller 440 controls the variable IF aperture 530 so that the aperture through which the beam passes at the intermediate focus is of a desirable size. The system controller places the signals controlling the various devices on an output bus 490.

[0068] Much of the above description is in terms of the system choosing one of two plasma production recipes but one of ordinary skill in the art will readily appreciate that a library of more than two plasma production recipes can be made available to the source . In some embodiments a controller provided data on scanner and / or illuminator settings could control the source in accordance with the a plasma production recipe which has been determined to provide the best results for that particular scanner setting, illuminator setting, or combination of scanner and illuminator setting.

[0069] For example, FIG. 13 shows a photolithography system 500 that includes an illumination system or source 505. As described more fully below, the source 505 includes a radiation source that uses a plasma to produce a pulsed radiation beam 510 and directs it to a photolithography exposure apparatus 515 such as a scanner that patterns microelectronic features on a wafer 520. The source 505 may include a plasma production recipe library 506 that may be, for example, a memory containing operational parameters for a multiplicity of plasma production recipes. Although in the example shown in FIG. 13 the plasma production recipe library 506 is shown as being part of the source 505 one of ordinary skill in the art will appreciate that the plasma production recipe library 506 could be physically associated with another part of the photolithography system 500.

[0070] The wafer 520 is placed on a wafer table 525 constructed to hold the wafer 520 and connected to a positioner 530 configured to position the wafer 520 in accurately accordance with certain parameters. The pulsed radiation beam 510 may have a wavelength in the EUV range.

[0071] The photolithography exposure apparatus 515 includes an optical arrangement 535 including a mask that enables an image transfer to occur from the mask to photoresist on the wafer 520. The optical arrangement 535 may adjust the range of angles for the pulsed radiation beam 510 impinging on the mask.

[0072] The photolithography exposure apparatus 515 can include, among other features, a lithography controller 540 that controls how layers are printed on the wafer 520. The lithography controller 540 may include a memory that stores information such as process recipes. The process recipes among other things determine the parameters of the pulsed radiation beam 510 including a length of the exposure on the wafer 520 based on, for example, the mask used, as well as other factors that affect exposure. During lithography, a burst of pulses of the pulsed radiation beam 510 illuminates the same area of the wafer 520 a specified number of times to constitute an illumination dose forthat area.

[0073] The photolithography system 500 also preferably includes a control system 545. In general, the control system 545 includes one or more of digital electronic circuitry, computer hardware, firmware, and software. The control system 545 can be centralized or be partially or wholly distributed throughout the photolithography system.

[0074] In an arrangement such as that just described, the source 505 can transition from one plasma production recipe to another directly in response to a user input directly commanding a new plasma production recipe or automatically. An example of automatic transition may occur based on receipt of data commanding a change in the production process currently being carried out by the photolithography system 500. The source 505 or a controller controlling the source 505 could then use that data to automatically transition the source 505 to using a plasma production recipe that has been determined to be better than a then-current recipe for that particular production process

[0075] As another example, the optical arrangement 535 could transition to imaging a new pattern. Then, the photolithography system 500 would provide the source 505 with data identifying the newpatern. The source 505 could then use the best plasma recipe for that patern in plasma production recipe library 506.

[0076] As another example, as mentioned above, the photolithography exposure apparatus 515 may provide an indication of the intended use of a new pupil configuration or a new pupil fill ratio. The photolithography exposure apparatus 515 may also provide an indication of a transition to a different reticle. The photolithography exposure apparatus 515 could use any of this information to decide whether to transition to operating according to a different plasma production recipe.

[0077] In other words, in some arrangements a feedback loop is established that includes the photolithography exposure apparatus 515 and the source 505. The photolithography exposure apparatus 515 receives information identifying a change in some operational parameter or operational condition and relays that information to the source 505. The source 505 then uses that information adopt the use of a plasma production recipe that is best suited among a multiplicity of available plasma production recipes for the new value of the operational parameter or operational condition.

[0078] As another example, it may be that a fabrication process about to be undertaken is a die repair operation. The plasma production recipe library may include a recipe that has been determined to be the best recipe for die repair. Alternatively, the photolithography exposure apparatus 515 may have an indication that the current type of circuitry being imaged is memory circuitry or microprocessor circuitry. The photolithography exposure apparatus 515 can relay this information to the source 505 which can use a plasma production recipe that has been determined to be the best for fabricating memory circuitry or microprocessor circuitry, respectively. Alternatively, the photolithography exposure apparatus 515 may have an indication that the next layer to be produced is a critical layer. The photolithography exposure apparatus 515 can relay this information to the source 505 which can use a plasma production recipe that is known to produce an especially stable plasma.

[0079] As another example, as noted above, a conditioning pulse such as a rarefication pulse could be turned off completely or, to the same effect, its timing could be changed so that the conditioning pulse occurs after the main conversion pulse so that the conditioning pulse does not cause the target to expand before conversion. Thus, the main conversion pulse converts a dense distribution of material.

[0080] There may be circumstances in which it will be desirable to limit the availability of operation under a particular plasma production recipe. For example, it may be that operating in the conversionpulse-only mode just described for more than a limited amount of time could lead to debris mitigation issues. The system could permit operation in the conversion-pulse-only mode for a predetermined amount of time before prohibiting additional operation in that mode at least temporarily.

[0081] As shown in FIG. 14, various embodiments and components therein can be implemented, for example, using one or more well-known computer systems, such as, for example, the example embodiments, systems, and / or devices shown in the figures or otherwise discussed. Computer system 1200 can be any well-known computer capable of performing the functions described herein.

[0082] Computer system 1200 includes one or more processors (also called central processing units, or CPUs), such as a processor 1210. Processor 1210 is connected to a communication infrastructure or bus 1220.

[0083] One or more processors 1210 may each be agraphics processing unit (GPU). In an embodiment, a GPU is a processor that is a specialized electronic circuit designed to process mathematically intensive applications. The GPU may have a parallel structure that is efficient for parallel processing of large blocks of data, such as mathematically intensive data common to computer graphics applications, images, videos, etc.

[0084] Computer system 1200 also includes user input / output device(s) 1230, such as monitors, keyboards, pointing devices, etc., that communicate with communication infrastructure 1220 through user input / output interface(s) 1240.

[0085] Computer system 1200 also includes a main or primary memory 1250, such as random access memory (RAM). Main memory 1250 may include one or more levels of cache. Main memory 1250 has stored therein control logic (i.e., computer software) and / or data.

[0086] Computer system 1200 may also include one or more secondary storage devices or memory 1260. Secondary memory 1260 may include, for example, a hard disk drive 1280 and / or a removable storage device or drive 1290. Removable storage drive 1290 may be a floppy disk drive, a magnetic tape drive, a compact disk drive, an optical storage device, tape backup device, and / or any other storage device / drive.

[0087] Removable storage drive 1290 may interact with a removable storage unit 1300. Removable storage unit 1300 includes a computer usable or readable storage device having stored thereon computer software (control logic) and / or data. Removable storage unit 1300 may be a floppy disk, magnetic tape, compact disk, DVD, optical storage disk, and / any other computer data storage device. Removable storage drive 1290 reads from and / or writes to removable storage unit 1300 in a well-known manner.

[0088] According to an example embodiment, secondary memory 1260 may include other means, instrumentalities, or other approaches for allowing computer programs and / or other instructions and / or data to be accessed by computer system 1200. Such means, instrumentalities or other approaches may include, for example, a removable storage unit 1310. Examples of the removable storage unit 1310 may include a program cartridge and cartridge interface (such as that found in video game devices), a removable memory chip (such as an EPROM or PROM) and associated socket, a memory stick and USB port, a memory card and associated memory card slot, and / or any other removable storage unit and associated interface.

[0089] Computer system 1200 may further include a communication or network interface 1320. Communication interface 1320 enables computer system 1200 to communicate and interact with any combination of remote devices, remote networks, remote entities, etc. (individually and collectively referenced by reference number 1330). For example, communication interface 1320 may allow computer system 1200 to communicate with remote devices 1330 over communications path 1340,which may be wired and / or wireless, and which may include any combination of LANs, WANs, the Internet, etc. Control logic and / or data may be transmitted to and from computer system 1200 via communications path 1340.

[0090] In an embodiment, a non-transitory, tangible apparatus or article of manufacture comprising a non-transitory, tangible computer useable or readable medium having control logic (software) stored thereon is also referred to herein as a computer program product or program storage device. This includes, but is not limited to, computer system 1200, main memory 1250, secondary memory 1260, and removable storage units 1290 and 1300, as well as tangible articles of manufacture embodying any combination of the foregoing. Such control logic, when executed by one or more data processing devices (such as computer system 1200), causes such data processing devices to operate as described herein.

[0091] A single EUV light source could be operated in multiple imaging modes using multiple plasma recipes. This would enhance the type of chips that could be produced and deliver more flexibility to lithography processes.

[0092] Some of the above description is in terms of functional block diagrams with some functions allocated to some blocks and other functions allocated to other blocks. It will be understood that the division between blocks and the allocations are arbitrary and that different divisions and allocations are possible so long as the overall functions are carried out as described above.

[0093] The above description includes examples of multiple embodiments. It is, of course, not possible to describe every conceivable combination of components or methodologies for each of these embodiments, but one of ordinary skill in the art may recognize that many further combinations and permutations of elements of the various embodiments are possible based on the disclosure. Accordingly, the described embodiments are intended to be representative of and encompass all such alterations, modifications, and variations that fall within the spirit and scope of the appended claims.

[0094] Furthermore, to the extent that the term “includes” is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term “comprising” as “comprising” is construed when employed as a transitional word in a claim. Also, although elements of the described aspects and / or embodiments may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated. Additionally, all or a portion of any aspect and / or embodiment may be utilized with all or a portion of any other aspect and / or embodiment, unless stated otherwise.

[0095] Features, materials, characteristics, or groups described in conjunction with a particular aspect, embodiment, or example are to be understood to be applicable to any other aspect, embodiment or example described in this section or elsewhere in this specification unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutuallyexclusive. The protection is not restricted to the details of any foregoing embodiments. The protection extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[0096] Furthermore, certain features that are described in this disclosure in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations, one or more features from a claimed combination can, in some cases, be excised from the combination, and the combination may be claimed as a subcombination or variation of a subcombination.

[0097] Moreover, while operations may be depicted in the drawings or described m the specification in a particular order, such operations need not be performed in the particular order shown or in sequential order, or that all operations be performed, to achieve desirable results. Other operations that are not depicted or described can be incorporated in the example methods and processes. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the described operations. Further, the operations may be rearranged or reordered in other implementations. Those skilled in the art will appreciate that in some embodiments, the actual steps taken in the processes illustrated and / or disclosed may differ from those shown in the figures. Depending on the embodiment, certain of the steps described above may be removed, others may be added.

[0098] Furthermore, the features and attributes of the specific embodiments disclosed above may be combined in different ways to form additional embodiments, all of which fall within the scope of the present disclosure. Also, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described components and systems can generally be integrated together in a single product or packaged into multiple products.

[0099] For purposes of this disclosure, certain aspects, advantages, and novel features are described herein. Not necessarily all such advantages may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the disclosure may be embodied or carried out in a manner that achieves one advantage or a group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein.

[0100] Conditional language, such as “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements, and / or steps. Thus, such conditional language is not generally intended to imply that features, elements, and / or steps are in any way required for one or more embodiments or that one or more embodimentsnecessarily include logic for deciding, with or without user input or prompting, whether these features, elements, and / or steps are included or are to be performed in any particular embodiment.

[0101] Conjunctive language such as the phrase “at least one of X, Y, and Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be either X, Y, or Z. Thus, such conjunctive language is not generally intended to imply that certain embodiments require the presence of at least one of X, at least one of Y, and at least one of Z.

[0102] Language of degree used herein, such as the terms “approximately,” “about,” “generally,” and “substantially” as used herein represent a value, amount, or characteristic close to the stated value, amount, or characteristic that still performs a desired function or achieves a desired result. For example, the terms “approximately”, “about”, “generally,” and “substantially” may refer to an amount that is within less than 10% of, within less than 5 % of, within less than 1% of, within less than 0.1 % of, and within less than 0.01 % of the stated amount.

[0103] The scope of the present disclosure is not intended to be limited by the specific disclosures of preferred embodiments in this section or elsewhere in this specification, and may be defined by claims as presented in this section or elsewhere in this specification or as presented in the future. The language of the claims is to be interpreted broadly based on the language employed in the claims and not limited to the examples described in the present specification or during the prosecution of the application, which examples are to be construed as non-exclusive.

[0104] The implementations can be further described using the following clauses.1. A multimode extreme ultraviolet (EUV) radiation source comprising: a drive laser source adapted to produce EUV radiation by converting a target material into a plasma; a memory for storing a first plasma recipe and a second plasma recipe, the first plasma recipe including a first set of specifications for generating a plasma according to a first priority and the second plasma recipe including a second set of specifications for generating a plasma according to a second priority; and a controller arranged to receive a selected one of the first plasma recipe and the second plasma recipe, and adapted to control the drive laser source in accordance with the first set of specifications if the first plasma recipe is the selected one of the first plasma recipe and the second plasma recipe and in accordance with the second set of specifications if the second plasma recipe is the selected one of the first plasma recipe and the second plasma recipe.2. The radiation source of clause 1, wherein first plasma recipe includes specifications for generating a plasma according to a first priority of wafer throughput and the second plasma recipe includes specifications for generating a plasma according to a second priority of image quality.3. The radiation source of clause 1 , wherein the specifications include an energy of a pulse of drive laser radiation.4. The radiation source of clause 1 , wherein the specifications include a duration of a pulse of the drive laser radiation.5. The radiation source of clause 1, wherein the specifications include a spatial distribution of a pulse of drive laser radiation.6. The radiation source of clause 1 , wherein the specifications include a temporal distribution of a pulse of drive laser radiation.7. The radiation source of clause 1, further comprising at least one conditioning laser adapted to produce conditioning laser radiation to condition the target material before being converted to the plasma by drive laser radiation.8. The radiation source of clause 7, wherein the specifications include an energy of a pulse of the conditioning laser radiation.9. The radiation source of clause 7, wherein the specifications include a duration of a pulse of the conditioning laser radiation.10. The radiation source of clause 7, wherein the specifications include a spatial distribution of a pulse of the conditioning laser radiation.11. The radiation source of clause 7, wherein the specifications include a temporal distribution of a pulse of conditioning laser radiation.12. The radiation source of clause 1, further comprising a target generator adapted to produce at least one target comprising a droplet of source material that produces the extreme ultraviolet radiation after being converted to a plasma by the drive laser source and wherein the specifications include one or more droplet specifications.13. The radiation source of clause 12, wherein the droplet specifications include droplet size.14. The radiation source of clause 12, wherein the droplet specifications include droplet coalescence.15. The radiation source of clause 1, further comprising a variable aperture placed in a beam path of the extreme ultraviolet radiation and wherein the specifications include a shape or size of the variable aperture.16. A method of using an extreme ultraviolet (EUV) source to provide EUV radiation to a wafer, the method comprising: determining one or more metrics of the EUV radiation to be delivered to the wafer, the one or more metrics resulting from prioritizing imaging performance or from prioritizing throughput; selecting, from plasma recipes, a selected plasma recipe based on the one or more metrics; and controlling the EUV source to generate the plasma based on the selected plasma recipe.17. The method as in clause 16, wherein the plasma recipe is selected based on a pupil pattern.18. The method as in clause 16, wherein the plasma recipe includes a plasma size.19. The method as in clause 16, wherein the one or more metrics of the EUV radiation includes an edge placement error.20. A method of operating an extreme ultraviolet (EUV) radiation source comprising: producing drive laser radiation by converting a target into a plasma;selecting one of a first plasma recipe and a second plasma recipe, the first plasma recipe including a first set of specifications for generating a plasma according to a first priority and the second plasma recipe including a second set of specifications for generating a plasma according to a second priority; and controlling the drive laser radiation in accordance with the first set of specifications if the first plasma recipe is the selected one of the first plasma recipe and the second plasma recipe and in accordance with the second set of specifications if the second plasma recipe is the selected one of the first plasma recipe and the second plasma recipe.21. The method of clause 20, wherein first plasma recipe includes specifications for generating a plasma according to a first priority of wafer throughput and the second plasma recipe includes specifications for generating a plasma according to a second priority of image quality.22. The method of clause 20, wherein the specifications include an energy of a pulse of the drive laser radiation.23. The method of clause 20, wherein the specifications include a duration of a pulse of the drive laser radiation.24. The method of clause 20, wherein the specifications include a spatial distribution of a pulse of the drive laser radiation.25. The method of clause 20, wherein the specifications include a temporal distribution of a pulse of the drive laser radiation.26. The method of clause 20, further comprising producing conditioning laser radiation to condition the target before being converted to a plasma by the drive laser radiation.27. The method of clause 26, wherein the specifications include an energy a pulse of the conditioning laser radiation.28. The method of clause 26, wherein the specifications include a duration of a pulse of the conditioning laser radiation.29. The method of clause 26, wherein the specifications include a spatial distribution of the conditioning laser radiation.30. The method of clause 26, wherein the specifications include a temporal distribution of the conditioning laser radiation.31. The method of clause 20, further comprising producing at least one target comprising a droplet of source material that produces the extreme ultraviolet radiation after being converted to a plasma by the drive laser and wherein the specifications include one or more droplet specifications.32. The method of clause 31, wherein the droplet specifications include droplet size.33. The method of clause 31, wherein the droplet specifications include droplet coalescence.34. The method of clause 20, further comprising a controlling variable aperture placed in a beam path of the extreme ultraviolet radiation and wherein the specifications include a shape or size of the variable aperture.35. A multimode extreme ultraviolet (EUV) radiation source comprising: a photolithography exposure system including a photolithography exposure system controller adapted to cause the photolithography exposure system to operate in a specified mode; a laser radiation source adapted to produce pulses of laser radiation and including a laser radiation source controller adapted to control at least one of pulse energy, pulse duration, pulse spatial distribution, and pulse temporal distribution of the pulses of the laser radiation; and a plasma production recipe library containing a plurality of plasma production recipes specifying at least one of pulse energy, pulse duration, pulse spatial distribution, and pulse temporal distribution of the pulses of the laser radiation, the photolithography exposure system controller being further adapted to supply an indication of the specified mode to the laser radiation source controller and the laser radiation source controller being further adapted to select a selected one of the plurality of plasma production recipes based the indication of the specified mode and control operation of the laser radiation in accordance with the selected one of the plurality of plasma production recipes.36. The radiation source of clause 1, wherein the drive laser source includes at least one drive laser.37. The radiation source of clause 1, wherein the drive laser source includes a gaseous laser and a solid- state laser.38. The method of clause 16, wherein controlling the EUV source includes emitting first radiation from a conditioning laser and emitting second radiation from a main laser to change a plasma size of the EUV source.

[0105] The above-described implementations and other implementations are within the scope of the following claims.

Claims

CLAIMS1. A multimode extreme ultraviolet (EUV) radiation source comprising: a drive laser source adapted to produce EUV radiation by converting a target material into a plasma; a memory for storing a first plasma recipe and a second plasma recipe, the first plasma recipe including a first set of specifications for generating a plasma according to a first priority and the second plasma recipe including a second set of specifications for generating a plasma according to a second priority; and a controller arranged to receive a selected one of the first plasma recipe and the second plasma recipe, and adapted to control the drive laser source in accordance with the first set of specifications if the first plasma recipe is the selected one of the first plasma recipe and the second plasma recipe and in accordance with the second set of specifications if the second plasma recipe is the selected one of the first plasma recipe and the second plasma recipe.

2. The radiation source of claim 1, wherein first plasma recipe includes specifications for generating a plasma according to a first priority of wafer throughput and the second plasma recipe includes specifications for generating a plasma according to a second priority of image quality.

3. The radiation source of claim 1 , wherein the specifications include an energy of a pulse of drive laser radiation.

4. The radiation source of claim 1 , wherein the specifications include a duration of a pulse of drive laser radiation.

5. The radiation source of claim 1 , wherein the specifications include a spatial distribution of a pulse of drive laser radiation.

6. The radiation source of claim 1, wherein the specifications include a temporal distribution of a pulse of drive laser radiation.

7. The radiation source of claim 1, further comprising at least one conditioning laser adapted to produce conditioning laser radiation to condition the target material before being converted to the plasma by drive laser radiation.

8. The radiation source of claim 7, wherein the specifications include an energy of a pulse of the conditioning laser radiation.

9. The radiation source of claim 7, wherein the specifications include a duration of a pulse of the conditioning laser radiation.

10. The radiation source of claim 7, wherein the specifications include a spatial distribution of a pulse of the conditioning laser radiation.

11. The radiation source of claim 7, wherein the specifications include a temporal distribution of a pulse of conditioning laser radiation.

12. The radiation source of claim 1, further comprising a target generator adapted to produce at least one target comprising a droplet of source material that produces the extreme ultraviolet radiation after being converted to a plasma by the drive laser source and wherein the specifications include one or more droplet specifications.

13. The radiation source of claim 12, wherein the droplet specifications include droplet size.

14. The radiation source of claim 12, wherein the droplet specifications include droplet coalescence.

15. A method of using an extreme ultraviolet (EUV) source to provide EUV radiation to a wafer, the method comprising: determining one or more metrics of the EUV radiation to be delivered to the wafer, the one or more metrics resulting from prioritizing imaging performance or from prioritizing throughput; selecting, from plasma recipes, a selected plasma recipe based on the one or more metrics; and controlling the EUV source to generate the plasma based on the selected plasma recipe.

16. The method of claim 15, wherein the plasma recipe is selected based on a pupil pattern.

17. The method of claim 15, wherein the plasma recipe includes a plasma size.

18. The method of claim 15 , wherein the one or more metrics of the EUV radiation includes an edge placement error.

19. The method of claim 15, wherein controlling the EUV source includes emitting first radiation from a conditioning laser and emitting second radiation from a main laser to change a plasma size of the EUV source.

20. A multimode extreme ultraviolet (EUV) radiation source comprising: a photolithography exposure system including a photolithography exposure system controller adapted to cause the photolithography exposure system to operate in a specified mode; a laser radiation source adapted to produce pulses of laser radiation and including a laser radiation source controller adapted to control at least one of pulse energy, pulse duration, pulse spatial distribution, and pulse temporal distribution of the pulses of the laser radiation; and a plasma production recipe library containing a plurality of plasma production recipes specifying at least one of pulse energy, pulse duration, pulse spatial distribution, and pulse temporal distribution of the pulses of the laser radiation, the photolithography exposure system controller being further adapted to supply an indication of the specified mode to the laser radiation source controller, and the laser radiation source controller being further adapted to select a selected one of the plurality of plasma production recipes based the indication of the specified mode and control operation of the laser radiation in accordance with the selected one of the plurality of plasma production recipes.

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