Method and laser system for generating a plasma of a target material for generating a secondary radiation and / or for mediating a nuclear fusion reaction

Abstract

The invention relates to a method for generating a plasma (12) of a target material (14) for generating secondary radiation (16), in particular for generating EUV light, and / or for mediating a nuclear fusion reaction, wherein the method has a step of generating (S1) an excitation light beam (24) and a step of amplifying (S2) the excitation light beam (24) in order to form an amplified excitation light beam (46). Furthermore, the method has a step of producing (S3) a plurality of units (18) of the target material (14) and a step of exciting (S4) at least one unit (18) of the target material (14) using the amplified excitation light beam (46) and thereby generating the plasma (12) of the target material (14) in particular. According to the invention, the method has a step of modulating the excitation light beam (24) and / or the amplified excitation light beam (46) in such a way that a specified target trajectory (62) is set for the excited unit (18) of the target material (14) and / or at least one other unit. The invention further relates to a laser system (10) and to a method for producing microchips or semiconductor intermediate products.

Description

[0001] Method for generating a plasma of a target material for generating secondary radiation and / or mediating a nuclear fusion reaction, laser system for generating an enhanced excitation light beam and manufacturing process for producing microchips or semiconductor intermediates for producing microchips

[0002] BACKGROUND OF THE INVENTION

[0003] 1. Field of the invention

[0004] The invention relates to a method for generating a plasma of a target material for generating secondary radiation, in particular for generating EUV light, and / or for mediating a nuclear fusion reaction, wherein the method comprises the following steps: a) generating an excitation light beam and amplifying the excitation light beam to an enhanced excitation light beam; b) generating a plurality of units of the target material; c) exciting at least one unit of the target material with the enhanced excitation light beam and thereby in particular generating the plasma of the target material.

[0005] Furthermore, the invention relates to a laser system for generating an amplified excitation light beam for generating a plasma of a target material for generating secondary radiation, in particular for generating EUV light, and / or for mediating a nuclear fusion reaction, comprising: a) a beam source arrangement with at least one beam source configured to generate an excitation light beam; b) an optical preprocessing arrangement comprising a beam splitter arrangement configured to divide the excitation light beam into a plurality of excitation light partial beams; an optical waveguide arrangement configured to guide the excitation light partial beams along beam paths defined by the optical waveguide arrangement; and c) an amplifier arrangement comprising a plurality of optical amplifiers, each configured tod) to amplify at least one of the excitation light partial beams to form an enhanced excitation light partial beam, d) a combination unit configured to combine the enhanced excitation light partial beams to form an enhanced excitation light beam.

[0006] Furthermore, the invention relates to a manufacturing process for producing microchips or semiconductor intermediates for producing microchips.

[0007] 2. State of the art

[0008] In modern high technology, where there is a constant effort to push beyond previously accepted absolute limits and unlock new boundaries, a target material is often excited for a wide variety of applications using an excitation light beam that can have a particularly high power in a range of, for example, 10 kW to 100 kW.

[0009] During or as a result of this excitation with the excitation light beam, a plasma of the target material can be generated at a sufficiently high excitation beam power. Secondary radiation can be generated or emitted as a byproduct of plasma generation and / or by the plasma itself. This secondary radiation often has a particularly short wavelength, especially in the extreme ultraviolet (EUV) or even X-ray range, and exhibits a particularly high quality, being produced with a comparatively high yield. This secondary radiation can be used for a wide variety of applications in industry and research.

[0010] However, excitation with the excitation light beam can also, for example, mediate nuclear fusion of atoms present in the target material. For this purpose, a plasma of the target material can be generated at its surface, which is then repelled by a comparatively heated but essentially non-ionized inner surface of the target material. Due to a recoil effect of the plasma being ejected radially from the inner surface, an inner region of the target material is compressed particularly strongly radially inwards, i.e., concentrically. This generates a temperature in the inner region high enough for a nuclear fusion reaction to occur, with temperatures reaching up to 100 million degrees Celsius.Comparable methods known from the prior art for mediating nuclear fusion are referred to as inertial fusion or, alternatively, thermonuclear fusion, for example, due to the inertia of the generated plasma, which holds the target material together during the nuclear fusion reaction.

[0011] In other methods known from the prior art for mediating nuclear fusion, a proton beam can be generated within the target material by the excitation light beam, which in particular can be pulsed and have pulse durations in the picosecond range, which in turn can provide fusion energy required for the nuclear fusion reaction and thus mediate nuclear fusion of atoms of the target material.

[0012] In the production of integrated circuits, so-called microchips, semiconductor substrates (hereinafter referred to as "wafers"), which are often monocrystalline, are coated with a layer in a relatively early manufacturing step. This layer is then structured in subsequent manufacturing steps. Such structuring acts as a mask in further downstream manufacturing steps, enabling the functional layer beneath the coating to be etched, doped with foreign atoms (e.g., by ion implantation), or introduced into the structure by foreign materials (e.g., by LIGA and lift-off).

[0013] The aim of these process steps is, among other things, to fabricate transistors and conductive areas that connect the transistors on the wafers. The structuring can be introduced into the coating using various methods.

[0014] In photolithography, for example, the coating is a photosensitive coating, specifically a photoresist. Here, the photoresist is exposed to light of a specific wavelength, to which it is sensitive, in a particular pattern. This allows the chemical properties of the exposed areas of the photoresist, such as its solubility in a developer solution, to be influenced. Some photoresists polymerize the exposed areas, meaning their solubility decreases compared to the unexposed areas (so-called negative resists). Others become more soluble in the exposed areas compared to the unexposed areas (so-called positive resists).In any case, to form the structure in the photoresist and thus the mask for the functional layer located under the photoresist, the more soluble areas of the photoresist are removed using the developer solution.

[0015] To introduce the specific pattern into the photoresist, a masking element (hereinafter referred to as "photomask") is usually placed between the light source and the wafer, which, depending on the photoresist used (negative or positive), is designed as a negative or positive of the structure to be formed on the photoresist.

[0016] In conventional photolithography, the photomask either lies directly on the photoresist or is positioned just above it, i.e., spaced apart from it, resulting in a 1:1 relationship between the photomask and the resulting pattern on the photoresist. Since photomasks can only be scaled to a finite size, this method is essentially limited to feature sizes of a few hundred nanometers. Because smaller patterns enable microchips with significantly higher performance per unit area or volume (as this allows for more transistors to be implemented on the same small area), there is a general drive to reduce the size of the pattern to its absolute physical limits.

[0017] For this reason, projection exposure systems are generally used nowadays, in which a focusing optic is usually positioned between the photomask and the photoresist. This allows the photomask to be drastically reduced in size and projected onto the photoresist. This enables the photomasks to be manufactured more cheaply, as the structures of the photomask do not need to be as small. Furthermore, it allows for significantly smaller structures to be imaged onto the wafers compared to conventional photolithography. The photomask and the resulting structure on the photoresist can then be present in a ratio of, for example, 5:1 or greater. The photomask itself can be designed as an absorptive or a reflective photomask.

[0018] Since the reduced image size of the photomask on the photoresist does not allow the entire wafer to be covered, prior art methods often employ a so-called "step-and-repeat" process: the wafer is exposed at a first exposure position, moved a certain distance, and then exposed again at a second exposure position. This process is repeated until the wafer is largely covered with instances of the same pattern. After the more soluble areas of the photoresist have been removed and the underlying functional layer has been treated, for example, by etching, the photoresist is often removed from the functional layer by a process called "stripping."

[0019] For multi-layered microchips, the projection exposure method described above can be performed up to one hundred times for the same microchip.

[0020] Generation of secondary radiation for the production of microchips and mediation of nuclear fusion

[0021] Besides reducing the size of the photomask and using focusing optics, another way to reduce the size of the pattern on the wafers is to use light with a shorter wavelength for exposure.

[0022] In processes known from the prior art, extreme ultraviolet (EUV) light with a wavelength in the range of approximately 8 nm to approximately 15 nm is generated during or as a result of the plasma generation of the target material and as a component of secondary radiation, sometimes referred to as "plasma luminescence." A major component of the EUV light lies at 13.5 nm, which is directed onto the photoresist by means of EUV projection optics and EUV focusing optics in the projection exposure system. In other processes outside of microchip manufacturing, the plasma luminescence can also include X-ray components that can be used for other applications, or X-ray components of the plasma luminescence can be used for other applications.

[0023] An EUV light generation system used for microchip manufacturing essentially comprises a laser system, sometimes referred to as an EUV drive laser, which generates an excitation light beam; a target material generator, which produces units of the target material; and an EUV light generation chamber. Typically, a pulsed high-power laser is used as the EUV drive laser, and a droplet generator serves as the target material generator, enabling the injection of numerous units of the target material in droplet form into the EUV light generation chamber. To prevent damage to the system due to particle contamination, a high vacuum under a process gas atmosphere can be maintained within the EUV light generation chamber in prior art implementations. Hydrogen (Hz) or helium (He) are particularly suitable process gases.In prior art processes for generating EUV light, tin (Sn) is frequently used as the target material. However, in addition to tin (Sn), target materials including xenon (Xe), gold (Au), and / or lithium (Li) are also possible.

[0024] In contrast, methods for mediating nuclear fusion can also use other target materials, such as a mixture of deuterium ( ) for a helium-producing nuclear fusion reaction. 2 H) and tritium ( 3 H) or from protons and the boron-11 isotope (p 11 B) may include.

[0025] To increase the amount of EUV light emitted during microchip manufacturing, for example, the droplets produced by the droplet generator can be excited first with a pre-pulse and then with a main pulse. The two excitation beams can be independent or generated by splitting a single beam. In principle, EUV light can be generated with only a single excitation beam; a second excitation beam is therefore not strictly necessary. However, using a second excitation beam significantly increases the conversion efficiency—the ratio of laser power input to EUV power output—in established methods.

[0026] This is because, in these known methods, the pre-pulse excitation causes a preconditioning of the target material droplet. Currently, this preconditioning involves the target material droplet forming an approximately disk-like shape due to the energy input from the pre-pulse, thereby comparatively increasing the surface area of ​​the target material droplet that can be excited by the second excitation light beam. The main pulse then strikes the preconditioned target material droplet, thereby exciting it. In the known methods, this excitation includes the generation of an ionized gas (plasma) of the target material—if the target material is a tin material, this results in the generation of a tin plasma. During or as a consequence of the generation of the tin plasma, the EUV light required for the formation of the structure in the photoresist is then generated as a component of secondary radiation.

[0027] In another known method, a third excitation light beam, in the form of a so-called rarefaction pulse, can be used for further preconditioning. This pulse strikes the target material droplet between the pre-pulse and the main pulse. In this known method, the rarefaction pulse causes the target material droplet, which has been shaped into a disk by the pre-pulse, to become a cloud of target material. The term "cloud" here is not to be equated with a gaseous or vapor state of the target material. The use of such a rarefaction pulse further increases the conversion efficiency.

[0028] The dilution pulse can be generated by splitting the initial excitation beam into the pre-pulse and the dilution pulse. Alternatively, a separate light source can be used for the dilution pulse, or even a single excitation beam can be split into the pre-pulse, the dilution pulse, and the main pulse. Furthermore, the dilution pulse can be designed as a temporally preceding segment of the main pulse, with a time-definable intensity distribution. In this case, it is sometimes referred to as a "pedestal."

[0029] EUV driver lasers are also conceivable, in which more than three excitation light beams are used to excite the target material and thus generate secondary radiation that includes EUV light.

[0030] In each of the above-mentioned cases, the main pulse hits the target material droplet with an average power in the range of 20 kW to 50 kW in the known methods.

[0031] In prior art methods where the excitation light beam is used to initiate or mediate nuclear fusion, multiple excitation light beams can also be employed. In some of these methods, it has proven advantageous to direct a plurality of excitation light beams temporally synchronously onto a unit of the target material to ensure the necessary input of photonic and / or thermal and / or relative kinetic energy for the nuclear fusion reaction. The multiple excitation light beams can, in particular, be directed equidistantly and / or onto the unit of the target material in such a way that the resultant momentum energy acting on the unit of the target material is zero, thus holding the unit of the target material in place during the nuclear fusion reaction and / or decelerating it during movement along a trajectory.However, there are also approaches in prior art methods to mediate nuclear fusion in a unit of the target material moving along the trajectory, thus enabling a nuclear fusion reaction to take place within the moving unit of the target material. Prior art laser systems, which in the context of generating secondary radiation including EUV light may occasionally be referred to as EUV driver lasers, can comprise a beam source arrangement, an optical preprocessing arrangement, an amplifier arrangement with a plurality of optical amplifiers, and a combination unit.

[0032] The beam source arrangement usually has at least one beam source that can generate the excitation light beam, which is then present at a certain point of an optical path, usually in a propagation direction of the excitation light beam behind the amplifier arrangement, as an amplified excitation light beam and is subsequently referred to as such.

[0033] If more than one excitation light beam is used to generate EUV light in the prior art methods, individual beam sources can be provided for each excitation light beam (pre-pulse, dilution pulse and main pulse), i.e. a pre-pulse beam source, a dilution pulse beam source and a main pulse beam source.

[0034] If one, two, three or more individual beam sources are used to generate the excitation light beam or the pre-, dilution and / or main pulse, these can generate the excitation light beams with the same or different wavelength and the same or different intensity, mode, beam caustics and / or polarization, or the excitation light beams can strike the target material droplet with the same or different wavelength and the same or different intensity, mode, beam caustics and / or polarization.

[0035] In conventional EUV driver lasers, the use of a solid-state laser as the pre-pulse beam source is known. Such a known solid-state laser generates the pre-pulse with a wavelength of approximately 1 pm. A solid-state laser can also be used as the dilution pulse beam source, preferably with a wavelength different from the pre-pulse, also approximately 1 pm, for example, for metrological purposes.

[0036] A CO2 laser, generating the main pulse with a wavelength of approximately 10.6 pm, is frequently used as the main pulse beam source. However, it is also possible to use a solid-state laser as the main pulse beam source, generating the main pulse with a wavelength in the range of approximately 1.6 pm to 2.3 pm. (Prior art problem)

[0037] A disadvantage of the prior art methods for generating a plasma of a target material to generate secondary radiation and / or to mediate a nuclear fusion reaction is that it involves considerable technical effort to provide an enhanced excitation light beam to a unit of the target material with certain specific beam properties, and the laser systems used to carry out the methods are comparatively susceptible to, for example, thermal drift, which in turn can negatively affect the beam properties.

[0038] This often results in the amplified excitation beam, used to excite the target material, striking the target material with undesirable beam properties. Even very small deviations from the desired beam properties can drastically reduce, for example, the conversion efficiency in the case of secondary radiation generation or the conversion efficiency in the case of mediating a nuclear fusion reaction.

[0039] One cause for a reduction in conversion efficiency can be that the amplified excitation beam is no longer ideally synchronized with the movement of the target material, resulting in suboptimal exposure. Thermal deformation of optics within the laser system is also possible, causing a change in the beam position of the amplified excitation beam at the target material. Furthermore, among numerous other possibilities, the beam properties of the excitation beam can change in such a way that an unfavorable photonic pulse acts on the target material. This pulse causes the target material to change its relative position to the excitation beam during exposure, meaning that it is no longer within the beam diameter of the excitation beam, at least partially and temporarily.This may, for example, necessitate an increase in the beam diameter at the point of impact of the amplified excitation light beam on the unit of the target material, and thus result in a decrease in the conversion efficiency.

[0040] Another disadvantage of the known methods is that, as a consequence of the excitation of the target material unit by the excitation light beam, significant contamination of surrounding components can occur due to the target material, which can only be removed with comparatively considerable effort. For example, it may be necessary to open a reaction chamber under high vacuum and evacuate it again after cleaning, which can lead to considerable downtime, for example in production and / or energy generation.

[0041] SUMMARY OF THE INVENTION

[0042] The object of the invention is therefore to provide the method described at the outset, which addresses the disadvantages mentioned above in the prior art.

[0043] This problem is solved according to the invention by the method mentioned at the outset, in which d) the excitation light beam and / or the amplified excitation light beam are modulated in such a way that a predetermined target trajectory is set by the excited and / or at least one further unit of the target material.

[0044] By modulating the excitation light beam and / or the amplified excitation light beam to set a predetermined target trajectory of the excited and / or at least one other unit of the target material, the aforementioned disadvantages known from the prior art can be overcome in a comparatively simple manner. The invention thus provides a technically surprisingly simple method for achieving an overall higher conversion efficiency of generated secondary radiation and / or a higher conversion efficiency of generated fusion energy as a result of a nuclear fusion reaction.

[0045] The desired trajectory of the excited and / or at least one other unit of the target material can be adjusted by modulating the excitation light beam and / or the amplified excitation light beam in such a way that, for example, non-ideal beam properties at an impact point of the amplified excitation light beam on the unit of the target material, thermal deformations of optics, or also, for example, insufficient temporal synchronization between a movement of the unit of the target material with the amplified excitation light beam, known in various applications, for example in the generation of EUV light, can be compensated by means of the adjusted desired trajectory of the unit of the target material.

[0046] It may be advantageous if the method is designed as a method for exciting a target material to generate a plasma of the target material to generate secondary radiation and / or for exciting the target material to generate a plasma of the target material to mediate a nuclear fusion reaction.

[0047] A desired trajectory of the excited and / or at least one further unit of the target material is understood here as a trajectory along which this unit of the target material is intended to move after being excited by means of the amplified excitation light beam. In other words, the desired trajectory is understood here as the motion of a geometric center of mass of this unit of the target material along a virtual line or curve.

[0048] The at least one unit of target material for which the desired trajectory is set can be the same unit of target material that was excited by the excitation light beam. Therefore, modulation of the excitation light beam and / or the amplified excitation light beam can occur almost in real time. Alternatively, the at least one unit of target material for which the desired trajectory is set can also be a unit of target material that follows the same, i.e., the excited, unit of target material in the context of a plurality of units of target material, for example, at least one more unit or at least one unit further down the list.It is therefore also possible that any number n of units of the target material lie between the excited unit and the at least one unit set with respect to the desired trajectory.

[0049] Preferably, the method according to the invention comprises the following steps between step c) and step d):

[0050] Capturing at least one unit of the target material and / or the plasma of the target material with respect to a shape and / or an absolute position in a reference space and / or a relative position with respect to the enhanced excitation light beam, in particular at least with respect to at least one beam parameter of the enhanced excitation light beam;

[0051] Determining a modulation value for the excitation light beam and / or the amplified excitation light beam.

[0052] Advantageously, the excitation light beam and / or the amplified excitation light beam are modulated according to the determined modulation value.

[0053] Preferably, the excitation light beam has a wavelength in the range of 1600 nm to 2300 nm, in particular in the range of 1800 nm to 2100 nm, in particular 1900 nm to 2050 nm, and especially preferably in the range of 1900 nm to 2000 nm.

[0054] Preferably, the excitation light beam comprises a plurality of pulses, and the amplified excitation light beam comprises a plurality of amplified pulses, wherein each amplified pulse of the amplified excitation light beam is traceable back to at least one original pulse of the excitation light beam. It is possible that exactly one pulse of the excitation light beam corresponds exactly to one amplified pulse of the amplified excitation light beam, i.e., that the pulses of the excitation light beam are each amplified to form amplified pulses of the amplified excitation light beam. Furthermore, it is also possible that several pulses of the excitation light beam are summed in an optical delay unit, for example, a Q-switch, to form an amplified pulse of the amplified excitation light beam.

[0055] The term "pulse" is understood here as a light pulse with a relatively short duration. Accordingly, a pulse has a start time and an end time. A pulse can be part of a sequence of several temporally successive light pulses of the same type, in the form of a pulse burst, and can be generated by a pulsed laser. The duration of a pulse, from its start time to its end time, can be in the range of microseconds, nanoseconds, picoseconds, or femtoseconds. Lasers operated in continuous wave (CW) mode must be distinguished from this. In particular, for inducing a nuclear fusion reaction, it is advantageous to use an excitation light beam with picosecond pulses.

[0056] Preferably, the at least one unit of the target material is excited with at least one amplified pulse of the amplified excitation light beam. Furthermore, the unit of the target material can also be excited with a plurality of pulses of the amplified excitation light beam, wherein only one, some, or all pulses may be modulated accordingly to set the predetermined desired trajectory of the excited and / or at least one further unit of the target material. If several pulses are used to excite the at least one unit of the target material, the pulses may be accumulated in pulse bursts. Pulse bursts are understood here as a sequence of pulses, preferably of the same type, between which there is a pause of duration ti, wherein there is a pause of duration t2 between the pulse bursts, and where t2 > ti.

[0057] Advantageously, at least one pulse of the excitation light beam and / or at least one amplified pulse of the amplified excitation light beam are modulated, at least temporally, segment by segment, thereby setting the predetermined target trajectory of the excited and / or at least one other unit of the target material. Particularly when an entire pulse duration is not required to set the predetermined target trajectory of the excited and / or at least one other unit of the target material, it can be advantageous to modulate only one, some, or all pulses of the excitation light beam and / or the amplified excitation light beam only temporally segment by segment, i.e., only over a temporal segment of the respective pulse.It is advantageous if at least one unit of the target material moves along an actual trajectory, at least one unit of the target material is excited at a specific excitation point of the actual trajectory, and if setting the predetermined target trajectory includes adjusting the actual trajectory to the predetermined target trajectory at the excitation point. This further development is particularly advantageous in applications of the invention where the units of the target material are introduced into a reaction chamber at particularly high pressure. In such applications, without appropriate modulation of the excitation light beam and / or the amplified excitation light beam, the unit of the target material, which must be adjusted with respect to the target trajectory, could follow an erroneous actual trajectory, which could drastically impair the conversion efficiency.In other words, in such applications, for example in the field of secondary radiation generation, it may be necessary to correct the movement or trajectory of the excited and / or at least one other unit of the target material with respect to a desired trajectory, in order to ensure, for example, exposure of the entire unit of the target material while maintaining a narrow beam diameter of the amplified excitation light beam.

[0058] Furthermore, it is advantageous if the adjustment of the actual trajectory to the predetermined target trajectory takes place under continuous movement of the excited and / or at least one further unit of the target material.

[0059] Preferably, the excitation light beam and / or the amplified excitation light beam are modulated with respect to one or more beam parameters selected from the following group of beam parameters:

[0060] Propagation direction, polarization of at least one polarization component, wavelength of at least one spectral component, spectral width, phase, mode, amplitude, and prominence of a chirp.

[0061] Furthermore, preferably the at least one pulse of the excitation light beam and / or the at least one amplified pulse of the amplified excitation light beam are modulated with respect to one or more beam parameters selected from the following group of beam parameters:

[0062] Pulse duration, phase of at least one temporal pulse segment, mode of at least one temporal pulse segment, amplitude of at least one temporal pulse segment, and the intensity of a chirp of at least one temporal pulse segment are all parameters to be considered. It is particularly advantageous if the beam parameter with respect to which modulation is performed is the mode, especially the transverse mode, of at least one temporal pulse segment of the at least one pulse or amplified pulse. This is especially beneficial because, for example, thermal drift or insufficient temporal synchronization of the amplified excitation beam with the at least one unit of the target material can lead to an erroneous beam position, i.e., a beam position outside the intended range, of the amplified excitation beam at this and subsequent units of the target material.By modulating the mode of at least one temporal pulse segment, the intensity and / or phase distribution of the light within the amplified excitation beam can be adjusted to compensate for the erroneous beam position. After modulation, the intensity maximum of the mode can, for example, lie on the predetermined target trajectory or define a starting point of the predetermined target trajectory.

[0063] In particular, the mode in a cross-section can be asymmetric along at least one axis of symmetry, or alternatively along two mutually perpendicular axes of symmetry, and / or exhibit an eccentric intensity maximum.

[0064] Furthermore, it is advantageous if the beam parameter with respect to which modulation is performed is the amplitude of a chirp and / or the spectral width of at least one temporal pulse segment of the at least one pulse or the amplified pulse. By modulating an applied chirp, its amplitude, and / or its spectral width, the interference pattern of the amplified excitation beam can be altered. This allows for the creation of destructive interference and constructive interference segments within the amplified excitation beam, thus changing the position of the intensity maximum not by redistributing the light within the excitation beam, but rather by the mutual interaction of the light.

[0065] It is advantageous if the excitation light beam is divided temporally into a multitude of excitation light partial beams before amplification, which are individually amplified to amplified excitation light partial beams by means of an amplifier arrangement and combined temporally after amplification to form the amplified excitation light beam, in particular coherently, wherein the excitation light partial beams and the amplified excitation light partial beams, before being combined to form the amplified excitation light beam, each point along a temporal axis together form the excitation light beam.

[0066] Preferably, the enhanced excitation light partial beams are combined such that a) at least some of the enhanced excitation light partial beams propagate essentially without superposition parallel to each other and alongside each other along a common propagation direction, and / or b) at least some of the enhanced excitation light partial beams superimpose spatially and temporally on each other in the manner of a filled aperture, in particular such that they interfere constructively with each other at least in certain areas.

[0067] The amplified excitation light partial beams can be coherently combined, for example, in the manner of a "side-by-side combination" as described in the immediately preceding feature a). This means that the amplified excitation light partial beams do not overlap spatially, or only to an insignificant extent, but propagate parallel to each other and alongside each other along a propagation direction.

[0068] Furthermore, in accordance with the immediately preceding feature b), it is additionally or alternatively possible that the amplified partial beams are coherently combined in the manner of a so-called filled aperture. In this context, a filled aperture is understood to be an optical arrangement in which the amplified excitation light partial beams are superimposed, particularly in space and time.

[0069] Such a filled aperture can be generated, for example, by a mirror arrangement comprising multiple mirror zones, each with a different reflectivity, ranging from nearly completely transmissive to nearly completely reflective. Ideally, a first mirror zone has a reflectivity of nearly 0% and is coated with an anti-reflective coating, while a final mirror zone ideally has a reflectivity adapted to the power of the amplified excitation light partial beam already coherently combined up to that mirror zone. Advantageously, the number of mirror zones can correspond to the number of amplified excitation light partial beams to be combined.Furthermore, the reflectivities of one or more mirror zones arranged between the first mirror zone and the last mirror zone can also be adapted to the power of the enhanced excitation light partial beams already combined up to the corresponding mirror zones and, in particular, be smaller than the reflectivity of the last mirror zone.

[0070] However, such a filled aperture can also be realized by at least one, preferably several, diffractive optical elements (DOEs), for example diffraction gratings or diffraction lenses, wherein first diffractive optical elements can diffract the amplified excitation light partial beams in such a way that they propagate onto at least a second diffractive optical element, through which the amplified excitation light partial beams can be diffracted in such a way that they are coherently combined in a single combined amplified excitation light beam.

[0071] Preferably, partial pulses of at least one pulse of the excitation light beam, i.e., pulses that arise from splitting the excitation light beam into excitation light partial beams and that originate directly from the pulses of the excitation light beams, are modulated temporally after splitting into the excitation light partial beams in at least some or all excitation light partial beams and / or amplified excitation light partial beams in such a way that a predetermined transverse mode of the amplified excitation light beam is generated as soon as the amplified excitation light partial beams are combined with each other to form the amplified excitation light beam.

[0072] Advantageously, the predetermined transverse mode, in particular an intensity maximum of the predetermined transverse mode, of the amplified excitation light beam at the time of impact on the excited and / or at least one other unit of the target material, specifies the predetermined target trajectory of the unit of the target material.

[0073] Preferably, the enhanced excitation light beam propagates along a beam axis and a propagation direction at the time of impact on the excited and / or at least one further unit of the target material, wherein the predetermined desired trajectory of the excited and / or at least one further unit of the target material runs parallel, and in particular collinearly, to the beam axis in temporal terms after impact, in particular at least section by section.

[0074] Furthermore, preferably, or alternatively, an axis of intensity maximum at the time of impact on the excited and / or at least one further unit of the target material runs parallel, in particular collinearly, at least section by section to the predetermined target trajectory for the unit of the target material and / or to the beam axis.

[0075] Alternatively, the beam path, propagation direction, and axis of the intensity maximum can also run at an angle to at least one segment of the desired trajectory. This allows a photonic impulse to be exerted on the excited and / or at least one other unit of the target material at the moment the amplified excitation light beam strikes this unit, thereby enabling, for example, a curved desired trajectory for this unit of the target material.

[0076] According to a further aspect of the invention, the aforementioned problem is also solved by a laser system mentioned above for generating an enhanced excitation light beam for generating a plasma of a target material for generating secondary radiation, in particular for generating EUV light, and / or for mediating nuclear fusion, in which, according to the invention: e) the optical preprocessing arrangement comprises a control device with a plurality of control elements, each of which is configured to individually modulate at least one excitation light partial beam and / or at least one enhanced excitation light partial beam depending on a modulation value detectable or determinable by the control device.

[0077] The laser system can also have multiple beam sources, whereby the excitation light beams generated by these can perform different functions, such as preconditioning the unit of the target material before the actual excitation of the unit of the target material.

[0078] Preferably, the control elements are each configured to modulate the excitation light partial beams temporally synchronously.

[0079] It is also advantageous if the control device is configured to modulate the excitation light partial beams in such a way that a predetermined transverse mode and / or a predetermined spectral width and / or a predetermined chirp of the amplified excitation light beam can be generated along a propagation direction of the amplified excitation light partial beams behind the combination unit.

[0080] Furthermore, it is advantageous if the optical preprocessing arrangement is designed as an integrated component, i.e., as a closed and replaceable component in which the beam splitter arrangement and the optical waveguide arrangement are supported by a common support element, in particular essentially enclosed.

[0081] It is further advantageous if the optical preprocessing arrangement is designed as a photonic integrated circuit (PIC). Using such a PIC, preferably at least 50, preferably at least 200, particularly preferably at least 500, and even more preferably at least 1,000, 2,000, 5,000, or 10,000 excitation light partial beams can be generated. Preferably, the PIC, in particular the optical waveguide arrangement, comprises SiN, LiNb, and / or InP, particularly preferably LiNb.

[0082] It is advantageous if the laser system includes a metrology device by means of which a beam of the amplified excitation light beam reflected back from the unit of the target material that can be excited by the amplified excitation light beam can be detected, and if the metrology device is configured to determine the modulation value for the control device as a function of the reflected beam.

[0083] Furthermore, it is advantageous if the optical preprocessing arrangement and the metrology device are configured to modulate the excitation light partial beams and / or the amplified excitation light partial beams within a time interval in the nanosecond range, particularly within a time interval of < 500 ns, preferably < 250 ns, most preferably < 100 ns, and most preferably < 50 ns, from the moment the amplified excitation light beam strikes the target material until the modulation value is transmitted to the control device. Modulation of the excitation light partial beams and / or the amplified excitation light partial beams in near real time is particularly advantageous. This makes it possible to perform modulations on the amplified excitation light beam very quickly while the target material is moving along its actual trajectory.

[0084] It is advantageous if at least one beam source and / or one, several, or all optical amplifiers are doped with an active medium. It is beneficial if the active medium is the same in the beam source and / or one, several, or all optical amplifiers.

[0085] Preferably, the active medium comprises holmium (Ho) and / or thulium (Tm). In the case of a first and a second active medium, these active media can also comprise holmium (Ho) and / or thulium (Tm). Pure thulium (Tm) doping is preferred, but mixed doping with thulium (Tm) and holmium (Ho) in varying relative concentrations of the dopants in the material to be doped is also conceivable and possible. Upon excitation, thulium (Tm) can emit light with a wavelength in the range of approximately 1600 nm to 2300 nm. The active medium can also comprise other lanthanide materials besides the two mentioned. Depending on which lanthanide materials are included in the active medium and their relative proportions, the emission spectrum of the active medium, the beam quality, and / or the beam profile of the emitted excitation light beam can be tailored.The optical amplifiers of the multiple optical amplifiers are preferably connected in parallel.

[0086] It is particularly advantageous if the laser system has the following immediately subsequent advanced features: a) the optical amplifiers of the plurality of optical amplifiers each comprise a solid-state amplifier, in particular a fiber amplifier, and / or b) the at least one beam source comprises a solid-state or semiconductor laser.

[0087] If the laser system includes at least one optical amplifier designed as a solid-state amplifier, the maximum achievable power for the excitation beam can theoretically be scaled arbitrarily, since the effort required to include further optical amplifiers in the amplifier arrangement is comparatively low. Consequently, the power output of generated secondary radiation, especially EUV light, and / or nuclear fusion energy can also theoretically be scaled arbitrarily.

[0088] It is advantageous if a major portion of the excitation beam, when the laser system is operating, is generated by stimulated emission. In other words, when the laser system is operating, a major portion of the excitation beam is generated by producing photons in a population inversion state within the at least one beam source, either by stimulating excited atoms and / or molecules and / or by spontaneous emission that triggers a chain reaction in excited atoms and / or molecules.

[0089] Preferably, the excitation light beam can be generated directly by converting the pumping energy of a pump source. By eliminating possible intermediate steps in the generation of the excitation light beam, power losses, e.g., due to elastic scattering, can be reduced.

[0090] Preferably, the laser system comprises one or more phase modulation units within the beam path of one, several, or all excitation light partial beams to compensate for possible differences in the propagation time of the excitation light partial beams by means of phase modulation. This advantageously ensures that the excitation light partial beams interfere constructively with each other – destructive interference, which would lead to the mutual cancellation of at least two excitation light partial beams, would be disadvantageous in this respect.

[0091] The amplified excitation light partial beams do not necessarily have to be coherent to each other in all aspects, but can, for example, exhibit different polarizations with the same or different phases. For this purpose, polarization modulation units can be arranged upstream of the combination unit in the propagation direction of the excitation light partial beams. According to a further aspect of the invention, the aforementioned problem is achieved by the aforementioned manufacturing process for producing microchips or semiconductor intermediates for producing microchips, in which, according to the invention, the steps of the aforementioned inventive process are used with some or all of the process steps or features mentioned in connection with the process, and / or a aforementioned inventive laser system is used with some or all of the features mentioned in connection with the laser system.

[0092] List of characters

[0093] Exemplary embodiments of the invention are explained in more detail below with reference to the drawings. These show:

[0094] Fig. 1 is a schematic representation of a first embodiment of a laser system according to the invention for generating an enhanced excitation light beam for generating a plasma of a target material for generating secondary radiation and / or for mediating a nuclear fusion reaction, wherein in Figure 1 the generation of an EUV light-emitting plasma of a unit of the target material is shown;

[0095] Fig. 2 is a schematic representation of a second embodiment of the laser system according to the invention, wherein in the figure 2 the generation of the plasma of the unit of the target material for mediating a nuclear fusion reaction within the unit of the target material is shown;

[0096] Figures 3a to 4b show a schematic representation of an excitation process known from the prior art of at least one unit of the target material by means of the amplified excitation light beam, wherein in figures 3a and 3b there is a target state and this unit of the target material moves along a target trajectory, and in figures 4a and 4b there is a fault state and this unit of the target material moves away from the target trajectory along a faulty actual trajectory;

[0097] Figures 5a to 6b show a first and a second embodiment of a method according to the invention for generating a plasma of a target material for generating secondary radiation and / or mediating a nuclear fusion reaction, wherein the first embodiment is shown in Figures 5a and 5b and the second embodiment in Figures 6a and 6b, wherein in the first embodiment the amplified excitation light beam is modulated such that insufficient temporal synchronization between the excited or a further unit of the target material and the amplified excitation light beam is compensated, and in the second embodiment, defective beam properties at the point of impact of the amplified excitation light beam on this or a further unit of the target material are compensated; Figure 7 shows a schematic representation of process steps of the method according to the invention;

[0098] Figs. 8a to 8c show an embodiment of the laser system according to the invention, in which amplified excitation light partial beams are coherently combined with each other in the manner of a “side-by-side combination” to form the amplified excitation light beam;

[0099] Figs. 9 to 11 show further embodiments of the laser system according to the invention, in which the amplified excitation light partial beams are combined coherently with each other to form the amplified excitation light beam in the manner of a “filled aperture”.

[0100] The invention is, of course, not limited to the embodiments shown. The embodiments shown in the figures merely represent concrete examples of the invention. Within the scope of their expert knowledge, a person skilled in the art can recognize embodiments of the invention that are not explicitly shown and identify features of the laser system as process features and vice versa without any inventive effort.

[0101] Reference symbol list

[0102] 10 laser systems

[0103] 12 Plasma of the target material

[0104] 14 Target material

[0105] 16 Secondary radiation

[0106] 18 units of target material

[0107] 20 Beam source arrangement

[0108] 22 Beam source

[0109] 24 Excitation light beam

[0110] 26 optical preprocessing arrangement

[0111] 28 Beam splitter arrangement

[0112] 30 Optical fiber arrangement

[0113] 32 Excitation light partial beam

[0114] 34 Beam path

[0115] 36 System propagation direction

[0116] 38 Amplifier arrangement

[0117] 40 optical amplifiers

[0118] 42 amplified excitation light partial beam

[0119] 44 Combination unit

[0120] 46 enhanced excitation light beam

[0121] 47 Multicore fiber

[0122] 47a Optical fiber channel

[0123] 48 Inner surface of the target material unit

[0124] 50 Interior of the target material unit

[0125] 52 Focusing unit

[0126] 54 Control unit

[0127] 56 Control element

[0128] 58 Metrology equipment

[0129] 60 back-reflected beam

[0130] 62 Target trajectory

[0131] 64 Transverse mode

[0132] 66 Pulse of the excitation light beam

[0133] 68 Pulse of the amplified excitation light beam

[0134] 70 Maximum intensity

[0135] 72 Beam axis

[0136] 74 geometric center of gravity

[0137] 76 Actual trajectory 78 Correction trajectory

[0138] 80 Transition point

[0139] 82 Propagation direction

[0140] 84 Side-by-side combination 86 Filled aperture

[0141] 88 Mirror arrangement

[0142] 90 first mirror unit

[0143] 92 Mirror zone

[0144] 94 second mirror unit 96 diffractive optical element

[0145] S procedure

[0146] S1-S5 process steps

[0147] DESCRIPTION OF PREFERRED EXAMPLES

[0148] Figures 1 and 2 schematically show exemplary embodiments of a laser system designated 10. A first embodiment of the laser system 10, shown in Figure 1, is configured to generate a plasma 12 of a target material 14 for producing secondary radiation 16, which, in the embodiment shown in Figure 1, is EUV light. A second embodiment of the laser system 10, shown in Figure 2, is configured to generate the plasma 12 of the target material 14 for mediating a nuclear fusion reaction within a unit 18 of the target material 14. In an embodiment of the laser system 10 not shown, it can also be configured to mediate a nuclear fusion reaction without the prior generation of a plasma 12 of the target material 14.For example, the laser system 10 can be configured to generate a proton beam within the target material 14, which provides fusion energy required for the nuclear fusion reaction. The laser system 10 according to Fig. 1 is configured here as an EUV driver laser, and the laser system 10 according to Fig. 2 is configured here as a fusion laser.

[0149] In the technical literature, plasmas that are generated by the input of light into the target material 14 are generally referred to as LPP (laser produced plasma).

[0150] The following refers to both the first and second embodiments of the laser system 10. Identical components are identified by the same reference numerals and are introduced only once for each embodiment, unless explicitly stated otherwise. Therefore, when referring to "the laser system 10" or, more generally, to corresponding components with a specific article without further specification, both embodiments are addressed equally.

[0151] The laser system 10 has a beam source arrangement 20, which in this case comprises only a single beam source 22. The beam source 22 is configured to generate an excitation light beam 24. In embodiments not shown, the beam source arrangement 20 can also comprise two or more beam sources 22, each capable of generating an excitation light beam 24. In these embodiments, the excitation light beams 24 can, for example, propagate along different propagation directions toward the unit 18 of the target material 14 and thus be directed toward the unit 18 of the target material 14 from different directions.

[0152] In addition, the laser system 10 has an optical preprocessing arrangement 26, which comprises a beam splitter arrangement 28 and an optical waveguide arrangement 30. The beam splitter arrangement 28 is configured to divide the excitation light beam 24 into a plurality of excitation light partial beams 32, of which, for clarity, only one excitation light partial beam 32 is shown with a reference numeral in Figures 1 and 2. For this purpose, the beam splitter arrangement 28 has at least one, preferably a plurality, beam splitters (not shown), each beam splitter being configured to divide a parent beam into at least two daughter beams. For example, the excitation light beam 24 can be divided into the plurality of excitation light partial beams 32 by connecting beam splitters of the same type in series.

[0153] The optical waveguide arrangement 30 is configured to guide the excitation light partial beams 32 along beam paths 34 defined by the optical waveguide arrangement 30. For clarity, each beam path 34 is also designated with a reference symbol only once. The beam paths 34 can be provided, for example, by individual optical waveguides that are not specifically designated with a reference symbol, such as elastic fibers, in particular glass fibers. Additionally or alternatively, it is also possible for the beam paths 34 to be provided, at least partially, by a comparatively inelastic conductor rod, which is also not designated with a reference symbol. For this purpose, the conductor rod can be designed as a multicore fiber and provide a multitude of beam paths 34 in the form of drawn fibers encased in a substantially rigid cladding, in particular a glass cladding.

[0154] The optical preprocessing arrangement 26 can, as is known from the prior art, be formed from optically interconnected individual components. In the present case, however, the optical preprocessing arrangement 26 is designed as an integrated component, specifically as a photonic integrated circuit (PIC). By means of the photonic integrated circuit, the excitation light beam 24 can be divided into a plurality of excitation light partial beams 32, and the excitation light partial beams 32 can each be guided in optical waveguides broadened by the photonic integrated circuit, which in turn define the beam paths 34 for the excitation light partial beams 32, preferably along a system propagation direction 36.

[0155] The laser system 10 further comprises an amplifier arrangement 38 with a plurality of optical amplifiers 40, of which, for the sake of clarity, only a single optical amplifier 40 is shown in Fig. 1 and provided with a reference numeral. Each optical amplifier 40 is configured to amplify at least one of the excitation light partial beams 32 to produce an amplified excitation light partial beam 42. Again, for clarity, only one excitation light partial beam 42 is provided with a reference numeral. In other words, each optical amplifier 40 can amplify at least one of its associated excitation light partial beams 32 to produce an amplified excitation light partial beam 42.

[0156] The laser system 10 further comprises a combination unit 44, which is configured to combine the amplified excitation light partial beams 42 into an amplified excitation light beam 46. The combination unit 44 can, for example, have a multicore fiber 47, wherein for each amplified excitation light partial beam 42 to be combined, an optical fiber channel 47a can be provided in the multicore fiber 47. With the amplified excitation light beam 46, it is then possible to excite the unit 18 of the target material 14 in order to generate, if necessary, a plasma 12 of the target material 14. The plasma 12 can then emit so-called "plasma light," which is addressed here as secondary radiation 16 and can include low-wave electromagnetic radiation, for example, EUV light, which is required for the production of microchips (see Fig. 1). In the case of the EUV driver laser, the target material 14 comprises a tin material.

[0157] Furthermore, it is also possible to mediate a nuclear fusion reaction within unit 18 of the target material 14 using the plasma 12. During excitation by the amplified excitation light beam 46, unit 18 of the target material 14 is heated intensely on the surface, thereby generating the plasma 12 of the target material 14. This plasma is subsequently repelled from a comparatively heated but essentially non-ionized inner surface 48 of unit 18 of the target material 14. Due to a recoil effect of the plasma 12 being ejected radially from the inner surface 48, an inner region 50 of unit 18 of the target material 14 is compressed particularly strongly radially inwards, i.e., concentrically. This generates a temperature in the inner region high enough for a nuclear fusion reaction to occur, with temperatures reaching up to 100 million degrees Celsius.In the case of the fusion laser, the target material 14 can include a fusion fuel, such as deuterium ( . 2 H)-Tritium ( 3 H) mixture or a proton-boron mixture (p 11 B) can include. In the nuclear fusion reaction, nuclei of the target material typically fuse to form helium (He) isotopes. The nuclear fusion reaction also releases a considerable amount of clean fusion energy, which can, for example, be fed into a city's power grid.

[0158] The laser system 10 further comprises a focusing unit 52, by means of which the amplified excitation light beam 46 can be focused onto the unit 18 of the target material 14. It is not necessary for the unit 18 of the target material 14 to be located within a region of the beam waist of the amplified excitation light beam 46 during excitation. It is also possible for the unit 18 of the target material 14 to be located 1 / 3, 1 / 2, 2 / 3, or a full Rayleigh length away from the beam waist during excitation with the amplified excitation light beam 46.The optical preprocessing arrangement 26, which is exemplified here as a photonic integrated circuit, comprises according to the invention a control device 54 with a plurality of control elements 56, each of which is configured to individually modulate at least one excitation light partial beam 32 of an adaptation signal detectable by the control device 54.

[0159] For this purpose, a metrology device 58 is provided as an example, by means of which a beam 60 of the amplified excitation light beam 46, which is reflected back from the unit 18 of the target material 14, is detected.

[0160] By means of the metrology device 58, if the unit 18 of the target material deviates from a target trajectory 62, which is only shown in Figures 3a to 6b, the adjustment signal is generated and transmitted to the control device 54. In response to the adjustment signal from the metrology device 58, the control elements 56 can modulate the excitation light partial beams 32 such that the target trajectory 62 is established for the unit 18 of the target material 14.

[0161] This setting of the target trajectory 62 can be done in real time, but it can also be done at predetermined time intervals, so that a deviation from the target trajectory 62 of a unit 18 of the target material 14 cannot have an immediate effect for exactly this unit 18, but only becomes noticeable at least in the next unit 18 of the target material 14 and consequently the target trajectory 62 is only set for this next unit 18.

[0162] The control elements 56 are configured to modulate the excitation light partial beams 32 in a temporally synchronous manner. In other words, the control elements 56 can modulate the excitation light partial beams 56 simultaneously in order to produce a specific modulation result in the amplified excitation light beam 46.

[0163] The control device 54 is hereby configured to modulate the excitation light partial beams 32 in such a way that a predetermined transverse mode 64 of the amplified excitation light beam 46 can be generated along a propagation direction of the amplified excitation light partial beams 42 behind the combination unit 44, which is not specifically designated.

[0164] In the present case, the excitation light beam 24 has a plurality of pulses 66, and the amplified excitation light beam 46 has a plurality of amplified pulses 68, wherein each amplified pulse 68 of the amplified excitation light beam 46 can be traced back to at least one original pulse 66 of the excitation light beam 24. Reference is now made to Figures 3a to 6b. Figures 3a to 4b illustrate methods known from the prior art, whereas Figures 5a to 6b schematically illustrate the method according to the invention.

[0165] Figures 3a and 3b illustrate a desired state: the amplified excitation light beam 46 is directed at the unit 18 of the target material 14, and the transverse mode 64 of the amplified pulse 68 incident on the unit 18 of the target material 14 has an intensity maximum 70, which lies on a beam axis 72 of the amplified excitation light beam 46. The unit 18 of the target material 14, in turn, also lies with a geometric center of gravity 74 on a virtual extension of the beam axis 72. Consequently, the unit 18 of the target material 14 can move along the desired trajectory 62, which in this case is collinear with the beam axis 72, due to a photonic pulse introduced onto the unit 18 by means of the amplified pulse 68.

[0166] Figures 4a and 4b illustrate a fault condition: for example, due to insufficient temporal synchronization between a unit 18 of the target material 14 moving along a trajectory not shown and the amplified excitation light beam 46, the unit 18, in the depicted fault condition, does not lie with its geometric center of gravity 74 on the beam axis 72. This causes a photonic pulse to be introduced into this unit 18 and all subsequent units 18 via the intensity maximum 70, resulting in the unit 18 deviating even further from the intended trajectory 62. The unit 18 of the target material 14 here follows an actual trajectory 76, which differs disadvantageously from the intended trajectory 62. The disadvantage of this is that, due to inhomogeneous illumination and thus excitation of the unit 18 of the target material 14, the conversion efficiency is reduced.the conversion efficiency drops drastically and the excited unit 18 as well as all subsequent units 18 of the target material 14 cannot, for example, be directed towards a disposal facility, which is not specifically shown, which can lead to contamination of surrounding components by the target material 14.

[0167] Figures 5a and 5b accordingly show a first embodiment of the method according to the invention, in which the error condition is remedied by selecting the intensity maximum 70 of the transverse mode 64 such that a corrective trajectory 78 is established for unit 18 and for subsequent units 18, which transitions into the target trajectory 62 at a transition point 80. The error condition shown in Figures 5a and 5b can occur, for example, if the amplified excitation light beam 46 and unit 18 are insufficiently synchronized temporally. Figures 6a and 6b show a further embodiment of the method according to the invention, wherein a [missing information] is shown in the figure.The fault condition shown in Figure 6a consists of faulty beam properties, represented here as a faulty transverse mode 64, in which the intensity maximum 70 does not lie on the beam axis 72 despite sufficient temporal synchronization of the amplified excitation light beam 46 and the unit 18 of the target material 14. Consequently, a photon impulse is introduced into the unit 18, causing it to move along a faulty actual trajectory 76.According to the inventive method, the faulty transverse mode 64 can, in accordance with an adaptation signal detected by the control device 54, cause the control elements 56 to modulate the excitation light partial beams 32 in such a way that the intensity maximum 70, which is decisive for the photonic pulse introduced onto the unit 18, is oriented in such a way that a target trajectory 62 is established for the unit 18 or for subsequent units 18 of the target material.

[0168] Figure 7 schematically illustrates a method S according to the invention. In a first process step S1, the excitation light beam 24 is generated. Furthermore, in a second process step S2, the excitation light beam 24 is amplified to an enhanced excitation light beam 46. In a third process step S3, which can be synchronous with process step S2 or shortly before or after it, a plurality of units 18 of the target material 14 are generated. In a fourth process step S4, at least one unit 18 of the target material 14 is excited with the enhanced excitation light beam, so that, for example, a plasma 12 of the target material is generated to produce secondary radiation and / or a nuclear fusion reaction is mediated within the unit 18 of the target material.In a fifth process step S5, the excitation light beam 24 and / or the amplified excitation light beam 46 is modulated in such a way that the predetermined target trajectory 64 of the excited and / or at least one further unit 18 of the target material 14 is set.

[0169] As shown in Figures 8a to 11, the amplified excitation light partial beams 42 can be combined with each other in different ways. As shown in Figures 8a to 8c, the amplified excitation light partial beams 42 can propagate essentially without superposition parallel to each other and side by side along a propagation direction 82 (Figure 8c). In this case, one can speak of a "side-by-side" combination 84.

[0170] However, as shown in Figures 9 to 11, it is also possible to superimpose the amplified excitation light partial beams 42 spatially and temporally in such a way that the amplified excitation light partial beams 42 essentially interfere constructively with each other. In this case, one can speak of a "filled aperture" 86. Here, the filled aperture is realized by means of a mirror arrangement 88 (Figure 10), which has a first mirror unit 90 with several mirror zones 92.1 to 92.5 and a second mirror unit 94. The mirror zones 92.1 to 92.5 have different reflectivities, which increase proportionally with the power of the amplified excitation light partial beam 42 combined up to the respective mirror zone 92, starting at the first mirror zone 92.1 and continuing to the last mirror zone 92.5.

[0171] The filled aperture 86 can also be realized by means of at least one diffractive optical element 96, onto which the amplified excitation light partial beams 42 are directed.

Claims

Claims 1. Method for generating a plasma (12) of a target material (14) for generating secondary radiation (16), in particular for generating EUV light, and / or for mediating a nuclear fusion reaction, wherein the method comprises the following steps (S1-S5): a) generating (S1) an excitation light beam (24) and amplifying (S2) the excitation light beam (24) to an amplified excitation light beam (46); b) generating (S3) a plurality of units (18) of the target material (14); c) Excitation (S4) of at least one unit (18) of the target material (14) with the amplified excitation light beam (46) and thereby, in particular, the generation of the plasma (12) of the target material (14), characterized in that d) the excitation light beam (24) and / or the amplified excitation light beam (46) are modulated such that a predetermined target trajectory (62) is established by the excited and / or at least one further unit (18) of the target material (14).

2. Method according to claim 1, characterized in that the excitation light beam (24) comprises a plurality of pulses (66) and the amplified excitation light beam (46) comprises a plurality of amplified pulses (68), wherein each amplified pulse (68) of the amplified excitation light beam (46) is traceable back to at least one original pulse (66) of the excitation light beam (24).

3. Method according to claim 2, characterized in that the at least one unit (18) of the target material (14) is excited with at least one amplified pulse (68) of the amplified excitation light beam (46).

4. Method according to claim 3, characterized in that at least one pulse (66) of the excitation light beam (24) and / or at least one amplified pulse (68) of the amplified excitation light beam (46) are modulated at least temporally in segments and thereby the predetermined target trajectory (62) of the excited and / or at least one further unit (18) of the target material (14) is set.

5. Method according to one of the preceding claims, characterized in that the at least one unit (18) of the target material (14) moves along an actual trajectory (76), the at least one unit (18) of the target material (14) is excited at a specific excitation location of the actual trajectory (76), and the setting of the predetermined target trajectory (62) by the excited and / or the at least one further unit (18) of the target material (12) comprises an adjustment of the actual trajectory (76) to the predetermined target trajectory (62) at the excitation location.

6. Method according to claim 5, characterized in that the adaptation of the actual trajectory (76) to the predetermined target trajectory (62) takes place under continuously continued movement of the excited and / or at least one further unit (18) of the target material (14).

7. Method according to one of the preceding claims, characterized in that the excitation light beam (24) and / or the amplified excitation light beam (46) are modulated with respect to one or more beam parameters selected from the following group of beam parameters: Propagation direction, polarization of at least one polarization component, wavelength of at least one spectral component, spectral width, phase, mode, amplitude, and prominence of a chirp.

8. Method according to one of claims 4 to 7, characterized in that the at least one pulse (66) of the excitation light beam (24) and / or the at least one amplified pulse (68) of the amplified excitation light beam (46) are modulated with respect to one or more beam parameters selected from the following group of beam parameters: Pulse duration, phase of at least one temporal pulse segment, mode of at least one temporal pulse segment, amplitude of at least one temporal pulse segment, severity of a chirp of at least one temporal pulse segment.

9. Method according to one of the preceding claims, characterized in that the excitation light beam (24) is divided temporally into a plurality of excitation light partial beams (32) before amplification, which are individually amplified to amplified excitation light partial beams (42) by means of an amplifier arrangement (38) and are combined temporally with one another to form the amplified excitation light beam (46), in particular coherently, wherein the Excitation light partial rays (32) and the enhanced excitation light partial rays (42) in temporal terms before combining to form the enhanced excitation light ray (46) at each point along a temporal axis, each form the excitation light ray (24).

10. Method according to claim 9, characterized in that the amplified excitation light partial beams (42) are combined such that a) at least some of the amplified excitation light partial beams (42) propagate in a side-by-side combination (84) essentially without superposition parallel to each other and alongside each other along a common propagation direction (82), and / or b) at least some of the amplified excitation light partial beams (42) superimpose spatially and temporally on each other in a filled aperture (86), in particular such that they constructively interfere with each other.

11. Method according to claim 9 or 10 with reference to one of claims 4 to 8, characterized in that partial pulses of the at least one pulse (66) of the excitation light beam (24) are modulated in temporal terms after division into the excitation light partial beams (32) at at least some or all excitation light partial beams (32) and / or amplified excitation light partial beams (42) in such a way as to be individually and in particular synchronously modulated over the excitation light partial beams (32) or the amplified excitation light partial beams (42) such that a predetermined transverse mode (64) of the amplified excitation light beam (46) is generated as soon as the amplified excitation light partial beams (32) are combined with each other to form the amplified excitation light beam (46).

12. Method according to claim 11, characterized in that the predetermined transverse mode (64), in particular an intensity maximum (70) of the predetermined transverse mode (62), of the amplified excitation light beam (46) at the time of impact on the excited and / or at least one further unit (18) of the target material (14) specifies the predetermined target trajectory (64) of this unit (18) of the target material (14).

13. Method according to one of the preceding claims, characterized in that the amplified excitation light beam (46) at the time of impact on the excited and / or at least one further unit (18) of the target material (14) propagated along a beam axis (72) and a propagation direction, wherein the predetermined target trajectory (62) of the excited and / or at least one further unit (18) of the target material (14) is parallel, in particular collinear, to the beam axis (72) in temporal terms after impact.

14. Laser system (10) for generating an enhanced excitation light beam (46) for generating a plasma (12) of a target material (14) for generating secondary radiation (16), in particular for generating EUV light, and / or for mediating a nuclear fusion reaction, comprising: a) a beam source arrangement (20) with at least one beam source (22) configured to generate an excitation light beam (24); b) an optical preprocessing arrangement (26) comprising a beam splitter arrangement (28) configured to split the excitation light beam (24) into a plurality of excitation light partial beams (32); an optical waveguide arrangement (30) configured to guide the excitation light partial beams (32) along beam paths (34) defined by the optical waveguide arrangement (30); c) an amplifier arrangement (38) with a plurality of optical amplifiers (40), each configured tod) a combination unit (44) configured to combine the amplified excitation light partial beams (42) into an amplified excitation light partial beam (46), characterized in that e) the optical preprocessing arrangement (26) comprises a control device (54) with a plurality of control elements (56), each configured to individually modulate at least one excitation light partial beam (32) and / or at least one amplified excitation light partial beam (42) depending on a modulation value detectable or determinable by the control device (54).

15. Laser system (10) according to claim 14, characterized in that the control elements (56) are each configured to modulate the excitation light partial beams (32) temporally synchronously.

16. Laser system (10) according to claim 14 or 15, characterized in that the control device (54) is configured to modulate the excitation light partial beams (32) such that a predetermined transverse mode (64) and / or a predetermined spectral width and / or a predetermined chirp of the amplified excitation light beam (46) can be generated along a propagation direction of the amplified excitation light partial beams (42) behind the combination unit (44).

17. Laser system according to any one of claims 14 to 16, characterized in that the optical preprocessing arrangement (26) is designed as an integrated component.

18. Laser system according to claim 17, characterized in that the optical preprocessing arrangement (26) is designed as a photonic integrated circuit (PIC).

19. Manufacturing process for producing microchips or semiconductor intermediates for producing microchips, characterized in that it comprises the steps of the process according to one of claims 1 to 13 and / or uses a laser system (10) according to one of claims 14 to 18.

Images