EP1632113A1 - Production de rayons x selon des procedes fondes sur l'utilisation de plasma, avec un materiau cible en couches - Google Patents

Production de rayons x selon des procedes fondes sur l'utilisation de plasma, avec un materiau cible en couches

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Publication number
EP1632113A1
EP1632113A1 EP04739766A EP04739766A EP1632113A1 EP 1632113 A1 EP1632113 A1 EP 1632113A1 EP 04739766 A EP04739766 A EP 04739766A EP 04739766 A EP04739766 A EP 04739766A EP 1632113 A1 EP1632113 A1 EP 1632113A1
Authority
EP
European Patent Office
Prior art keywords
target material
flow structure
vacuum chamber
irradiation
ray source
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP04739766A
Other languages
German (de)
English (en)
Inventor
Manfred Faubel
Bernd Abel
Ales Charvat
Eugene Lougovoi
Jens Assmann
Jürgen TROE
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Max Planck Gesellschaft zur Foerderung der Wissenschaften eV
Georg August Universitaet Goettingen
Original Assignee
Max Planck Gesellschaft zur Foerderung der Wissenschaften eV
Georg August Universitaet Goettingen
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Max Planck Gesellschaft zur Foerderung der Wissenschaften eV, Georg August Universitaet Goettingen filed Critical Max Planck Gesellschaft zur Foerderung der Wissenschaften eV
Publication of EP1632113A1 publication Critical patent/EP1632113A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05G—X-RAY TECHNIQUE
    • H05G2/00—Apparatus or processes specially adapted for producing X-rays, not involving X-ray tubes, e.g. involving generation of a plasma
    • H05G2/001—X-ray radiation generated from plasma
    • H05G2/003—X-ray radiation generated from plasma being produced from a liquid or gas
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05G—X-RAY TECHNIQUE
    • H05G2/00—Apparatus or processes specially adapted for producing X-rays, not involving X-ray tubes, e.g. involving generation of a plasma
    • H05G2/001—X-ray radiation generated from plasma
    • H05G2/008—X-ray radiation generated from plasma involving a beam of energy, e.g. laser or electron beam in the process of exciting the plasma

Definitions

  • the invention relates to methods for plasma-based generation of x-rays with the features of the preamble of claim 1, x-ray sources for plasma-based generation of x-rays with the features of the preamble of claim 22 and methods for injecting a liquid target material into a vacuum chamber.
  • the emission of soft X-rays occurs from the plasma state, which emerges through a window in the chamber or is collected with an optical system.
  • the X-ray source according to EP 186 401 is limited to the use of mercury as a liquid target material. Accordingly, the x-ray radiation that can be generated is limited to certain spectral lines.
  • Another disadvantage of mercury is its relatively high vapor pressure, which causes problems with mercury trapping and contaminants in the chamber. Liquid metals are generally incompatible with the sensitive and extremely cost-intensive X-ray optics. So on gold optics z. B.
  • a general disadvantage of the conventional plasma-based generation of X-rays is the low conversion effectiveness in the irradiation of the target material in order to generate the plasma state.
  • the conversion effectiveness may be increased, but at the same time it becomes more difficult with the increasing atomic mass to provide the target material in the liquid state.
  • the efficiency of the conversion of, in particular, liquid target material into the plasma state that is to say the ratio of the atoms or molecules of the target material excited in the plasma state to the irradiated energy of the laser light, is therefore relatively low.
  • BAM Hansson et al. (“Proceedings of SPIE", Vol. 4688, 2002, pp. 102-109) indicated an efficiency of only 0.75% for the generation of EUV light.
  • the object of the invention is to provide improved methods, in particular for the plasma-based generation of x-rays, with which the disadvantages of conventional techniques are overcome and which are characterized in particular by an increased efficiency in the generation of plasma and thus the generation of x-rays and a simplified fo kissability of the external radiation to generate the Mark the plasma state with constant or reduced material input into the vacuum chamber.
  • the object of the invention is also to provide improved target materials for plasma-based X-ray generation (in particular soft X-rays or extreme UV radiation), with which the disadvantages of conventional target materials are overcome and which are suitable for implementing the methods according to the invention.
  • the target materials are intended in particular to solve the conventional problems in collecting the target material and to avoid the generation of impurities.
  • it is also an object of the invention to provide an improved x-ray source which is suitable for carrying out the improved methods for plasma-based x-ray steel production.
  • the invention is based on the general technical teaching, a process for the plasma-based generation of X-rays, in which target material in the form of a free flow structure is irradiated in a vacuum chamber to generate a plasma state, in which the X-rays are emitted, so that white -
  • the flow structure is formed with a surface that has different radii of curvature, the target material having a surface with a local minimum of curvature (local
  • the target material is therefore irradiated at a point where the flow structure is less curved than along the surrounding surface, or even relative to other parts of the surface is oppositely (negatively) curved. This means that the cross-sectional area of the flow structure is deformed, deviating from the conventionally realized circular shape, into an elongated shape or, if necessary, at least concave on one side.
  • a free flow structure is generally a flowing liquid with a defined surface, z. B. understood in the form of a jet or a liquid layer flowing apart.
  • the liquid flows freely, i.e. with a surface that is free on all sides and without binding to a carrier through the vacuum chamber.
  • the flow structure has a fixed spatial shape, which is therefore essentially unchangeable over time.
  • the advantages of the flow structure shaped according to the invention result from the following findings of the inventors.
  • the inventors have found that increasing the diameter of a conventionally formed beam of the target material results in a significant improvement in the efficiency of the plasma generation. It was found that the improvement is not due solely to a larger amount of substance in the focus of the external radiation, but to the following effect.
  • a beam of the target material with an enlarged diameter has a less curved surface, which is more favorable for the coupling in of the external radiation energy. On a less curved surface, a larger proportion of the focused radiation can strike the target material with a steeper angle of incidence, so that reflection losses are reduced.
  • the invention solves this contradiction in that the flow structure has a non-circular cylindrical shape completely or at least at the location of the irradiation.
  • the radius of curvature of the target surface can thus be maximized at least locally while the material input remains the same.
  • free liquid structures can be created in vacuum which, contrary to the striving caused by the surface tension to form a cylindrical or spherical shape to minimize the surface area, are sufficiently stable to achieve the desired flow structure or pattern to form.
  • Irradiation of the flow structure at a local minimum surface curvature has a number of advantages.
  • the angle of incidence of the radiation can be optimized. Reflection losses are reduced.
  • the efficiency of plasma generation can be increased significantly.
  • the target material can offer a larger, free area for irradiation while the material input remains the same. This simplifies the focusing of laser light on the target material and enables the structure of the X-ray source to be simplified.
  • a target material with a relatively high vapor pressure with smaller beam dimensions can be introduced without the X-ray intensity being greatly reduced.
  • an anisotropic X-ray emission takes place in the method according to the invention. This can be used to further increase efficiency in the generation of X-rays. Furthermore is the anisotropy the emitted x-ray radiation can be measured in relation to the target surface and can also be set by a predetermined rotation of the target surface.
  • the flow structure which is formed in a free-standing manner in the vacuum chamber is provided with an elongated cross-sectional area.
  • the cross-sectional area given perpendicular to the main flow direction of the flow structure has a greater extent in a main axis direction than in a different, e.g. B. 90 ° on the major axis direction minor axis direction.
  • the local minimum of curvature is thus given on at least one side of the flow structure, which corresponds to the minimum transverse extent of the cross-sectional area.
  • This embodiment of the invention has the particular advantage that the target material provides a particularly large area for external radiation in accordance with the minor axis direction.
  • the cross-sectional area preferably has an oval, e.g. B. elliptical or a rounded, rectangular shape.
  • the flow structure forms a free-standing liquid layer or liquid lamella at least at the location of the external radiation.
  • the surface of the liquid layer can locally form a flat or vanishingly slightly curved surface, into which externally irradiated laser light can be coupled in particularly effectively.
  • the external radiation in particular with laser light on the target material is essentially perpendicular to the surface before the local minimum of curvature, e.g.
  • reflection losses during the irradiation can advantageously best be reduced and the efficiency of the plasma generation increased accordingly.
  • the flow structure is generated with a target source which has a nozzle with a non-circular cross section. It has surprisingly been found that the flow shape, which is impressed on the flow structure with a flattened nozzle, for example, is retained in the vacuum chamber over sufficiently long flow lengths. Special advantages for the generation of a liquid layer can result if a nozzle with a slit-shaped cross section is used.
  • the flow structure has a concave surface at least on one side or preferably on both sides, i. H. has a surface with a negative radius of curvature
  • the thickness of the flow structure can advantageously be reduced, in particular at the site of the irradiation. The material released in the vacuum chamber during the irradiation can thus be reduced.
  • the use of a rotatable nozzle with a non-circular cross section enables the setting of a predetermined orientation of the nozzle and thus of the target material relative to the direction of the irradiation of the target material.
  • the nozzle can be adjusted around an axis in accordance with the main flow direction of the flow structure so that the irradiation development of the target material takes place substantially perpendicular to the surface of the flow structure.
  • the flow structure is generated with two primary rays of the target material brought together at an angle. At the point where the primary rays meet, an all-round spreading occurs upon collision, in which an essentially layered flow structure is generated.
  • This variant can have advantages with regard to the flexibility in setting the flow structure by varying the flow properties of the primary jets involved.
  • an axially symmetrical flow structure can advantageously be generated. If the primary jets are brought together in opposite directions at an angle of 180 °, an axially symmetrical flow structure can advantageously be generated. If the primary beams are brought together at a smaller angle, there may be advantages for the structure of the X-ray source. Intersection angles of the primary beams are preferably chosen to be less than or equal to 180 ° (such as 120 °), in particular less than or equal to 90 °.
  • Another particular advantage of the invention is that the generation of the flattened flow structure with the known target materials for generating X-rays, such as. As water, glycerol, alcohol, liquefied gas, in particular liquefied noble gas, such as. B. Xenon or liquid metal can be realized.
  • a target material consisting of at least one hydrocarbon compound which comprises at least one polymer which is liquid at room temperature is preferred. The use of liquid, polymeric hydrocarbon compounds has one
  • the liquid, polymeric target material is not volatile. Hardly volatile substances can be removed particularly easily from a vacuum chamber in which the plasma is excited to generate radiation. The substances can be caught directly as a liquid in a trap and separated there under their own vapor pressure. A further vacuum system for evacuating the trap is not absolutely necessary, so that the structure of the X-ray source is considerably simplified.
  • the desired spatial shape of the flow structure can be generated with liquid polymers with a particularly high spatial stability.
  • the flattened surface of each flow structure can be provided with a comparatively large distance from the nozzle of the target source, for example up to 100 mm, which considerably simplifies the focusing of the external radiation.
  • the polymers used according to the invention reduce erosion damage in the vacuum chamber. The inventors have found that erosion damage can occur due to the interaction of the gas atmosphere, which is always formed by the vapor pressure of a liquid target, and the generated X-rays. Target molecules present in the gas atmosphere are ionized by the radiation. The deposition of the ions on surfaces in the vacuum chamber, e.g. B. on nozzles for introducing the target material, cause a plasma etching through which the respective material is eroded.
  • the target material which is polymeric according to the invention is not volatile, so that the particle concentration in the gas atmosphere and possible erosion damage are minimized.
  • the precipitation of polymeric target material in the vacuum chamber is not critical.
  • the polymers give rise to readily volatile products which can easily be pumped out of the vacuum chamber.
  • a target material precipitate can even act as a protective film on components of the vacuum chamber, which prevents high-energy polymer fragments from reaching the components directly and, if necessary, can be easily removed during cleaning.
  • the liquid polymer has at least one ether bond between carbon atoms.
  • a hydrocarbon with at least one ether bond (or oxygen bridge) achieves advantages which also have a positive effect on all phases of the plasma-based generation of X-rays.
  • the oxygen bridge connections between carbon atoms result in high molecular flexibility.
  • the low viscosity has an advantageous effect both on the generation of the flattened flow structure and on the disintegration into low molecular weight components after the plasma excitation.
  • the composition of the target material in particular of fluorine, carbon and oxygen, leads to an expanded area of use for the target material. A universal target for various applications is provided.
  • a polymer which is liquid at room temperature (around 20 ° C.) and comprises at least one partially fluorinated or perfluorinated, polymeric hydrocarbon ether is used as the target material.
  • the partial or complete fluorination of the polymer promotes the formation of volatile decomposition products under X-ray radiation.
  • a perfluoropolyether (PFPE) or a mixture of several perfluoropolyethers is preferably used as the target material.
  • PFPE compounds are of high molecular weight, which further promotes the formation of the flow structure. Furthermore, by breaking oxygen bridges when energy is supplied, they can decompose into volatile compounds that can be easily pumped off. This prevents deposits and contamination, especially on optical components in the X-ray source.
  • the invention advantageously protects the expensive and sensitive x-ray optics. Undecomposed residues of the target material can be collected particularly easily in a vacuum without special precautions for condensation.
  • the polymeric target material has a vapor pressure which is less than 10 mbar, preferably less than 1 mbar, at room temperature, z. B. 10 ⁇ mbar, is a molecular weight greater than 100 g / mol, preferably greater than 300 g / mol, e.g. B. in the range 400 to 8000 g / mol, and / or at room temperature a viscosity which is selected in the range of 1 to 1800 cS.
  • the mass density of the target material is preferably in the range from 1.5 to 2.5 g / mol, e.g. B. 1.8 to 1.9 g / mol.
  • the target material in particular the liquid polymeric target material
  • the target material is irradiated in an environment at a pressure which is greater than the gas pressure of the material released during the irradiation.
  • a pressure which is greater than the gas pressure of the material released during the irradiation.
  • the above-mentioned object is achieved by providing an X-ray source for plasma-based generation of X-radiation, which has a target source for providing the target material in the form of a free flow structure in a vacuum chamber and an irradiation device for high-energy irradiation of the target material and is further developed according to the invention for this purpose that the target source is set up to impress a flow shape on the target material, so that a flow structure is formed which has a local minimum of curvature in at least one surface area.
  • the target source has a nozzle with a non-circular cross section, with which the desired flow pattern is impressed on the target material.
  • a nozzle with a slot-shaped mouth is particularly preferred, since it can be used to form an essentially layered flow structure.
  • the nozzle in particular at its outlet opening, has a cross-sectional area that tapers inwards at least on one side.
  • the concave flow structure described above is advantageously formed. If the nozzle is rotatably arranged in the vacuum chamber, there can be advantages for the alignment of the flow structure for optimal external radiation.
  • the target source is equipped with two nozzles which are set up to generate primary jets which meet in the vacuum chamber at a predetermined angle. If the nozzles are directed towards each other at an angle of 180 °, there can be advantages for a uniform formation of the flow structure. If the nozzles are directed towards one another at an angle of less than or equal to 90 °, there may be advantages for the structure of the X-ray source and the flexibility in shaping the flow structure.
  • the x-ray source has at least one heating device with which at least parts of the vacuum chamber can be tempered.
  • the provision of the at least one heating device results in Particular advantages when using the above-mentioned polymeric target material, since the vapor pressure of the target material can be set higher than the pressure of the gas released by the irradiation of the target material with the heating device. By increasing the temperature, the vapor pressure can be increased, which provides advantages for the construction of the vacuum device and the reduction of precipitation.
  • the x-ray source is equipped with radiation optics arranged in the vacuum chamber for irradiating the target material, it can be advantageous to connect a heating device to the radiation optics, so that precipitation of the target material is avoided thereon.
  • the efficiency of the X-ray source increases. If the radiation optics are arranged outside the vacuum chamber, it is advantageously possible to dispense with a separate heating device on the radiation optics. The structure of the x-ray source is simplified.
  • the x-ray source is equipped with a collecting device for collecting coolant-free target material residues.
  • the X-ray source according to the invention has the advantage of a simplified structure.
  • the stability of the flow structure of the target material simplifies the adjustment of an irradiation device to excite the plasma state. Thanks to the use of a simple vacuum system and the avoidance of a complex cooling device, the X-ray source is suitable as a mobile device for an extended area of application in laboratories and in industry.
  • the X-ray lithography device can be arranged in the vacuum chamber in the immediate vicinity of the location of the X-ray radiation generation. In contrast to the conventional systems, this is possible for the first time because of the low droplet formation and reduced precipitation of the target material used according to the invention. Conversely, the x-ray source can be integrated directly into an x-ray lithography device.
  • the X-ray lithography device is preferably equipped with its own heating device, so that any residual precipitation that may occur can be easily converted into the gas phase and pumped out.
  • the vacuum chamber of the X-ray source can be combined with an additional vacuum chamber which contains the X-ray lithography device. Due to the simplified construction of the X-ray source according to the invention, both vacuum chambers can be arranged in a small space.
  • the x-ray source according to the invention has the particular advantage that x-ray radiation (or correspondingly radiation in the far UV range) can be generated during continuous operation.
  • the system can work practically continuously (e.g. over days), which is particularly important for industrial applications of the X-ray source.
  • a vacuum chamber with a nozzle with a slot-shaped outlet opening for the injection of liquid target material.
  • a liquid target material in the form of a free flow structure into a vacuum chamber, the flow structure being shaped so that the target material has a surface with a local curvature minimum and preferably forms a free, lamellar layer.
  • FIGS. 2 and 3 illustrations of the beam shaping with a slit-shaped nozzle
  • FIGS. 5 and 6 illustrations of a slit-shaped nozzle
  • FIGS. 7 and 8 illustrations for generating a surface target from two primary beams
  • FIGS. 9 and 10 Structural formulas for characterizing the target material used according to the invention.
  • FIGS. 11 to 14 schematic representations of embodiments of an X-ray source according to the invention.
  • FIG. 1 illustrates the generation and irradiation according to the invention of a liquid target material 50 which is freely standing in a vacuum under vacuum conditions and which has a surface which is at least slightly curved on one side.
  • the target material 50 is shaped as a flow structure, the cross-sectional area of which is exemplarily illustrated perpendicular to the flow direction.
  • the target material 50 is irradiated with an irradiation device 30 (see below). The radiation is directed onto the surface 52 of the flow structure 51, at which the local
  • Radius of curvature is maximum and the curvature is minimal.
  • the external irradiation with the entire focusing cross section can take place essentially perpendicularly on the surface 52.
  • the flow structure 51 has an elongated, in particular elliptical cross section.
  • the y direction forms a main axis direction in which the flow structure has the longitudinal dimension ⁇ y.
  • the x direction with the smaller transverse dimension ⁇ x forms the minor axis direction in which the irradiation also takes place.
  • the target material 50 has, for example, the following geometric parameters: longitudinal dimension ⁇ y: 100 ⁇ m to 20 mm, transverse dimension at the location of the irradiation ⁇ x: 2 ⁇ m to 2 mm, perpendicular distance of the illustrated cross-sectional area from the nozzle of a target source: 0.1 mm to 10 cm.
  • FIG. 2 shows the end of the nozzle 13 with the slot-shaped outlet opening 14, which projects into the vacuum chamber (see below).
  • the geometric structure of the nozzle as a slot nozzle is selected in accordance with the desired shape of the flow structure 51 (see also FIG. 5, 6).
  • the outlet opening 14 is formed for producing microjets according to the invention with correspondingly smaller dimensions.
  • the slot has a width of 0.1 mm and a length of 3 mm, for example.
  • Target material passes from the nozzle 13 through the slit-shaped outlet opening 14 into the vacuum chamber of the X-ray source.
  • the exit speed is set so that the target material does not freeze in the vacuum chamber and is, for example, approx. 20 to 100 m / s.
  • non-cylindrical jets can have a variable jet shape, which is dependent on the viscosity, the surface tension and the flow rate of the emerging liquid.
  • the non-cylindrical shape of the flow initially remains only over a finite range of a few millimeters.
  • a constriction 53 (FIG. 2) with an essentially circular cross section of the liquid target material is initially formed. Due to the inertia of the liquid moving in the jet, however, the liquid target material 50 is subsequently expanded 54 again.
  • the shape of the oscillating structure in particular the number of widenings 54 that are implemented and their distance from the nozzle, can be adjusted in particular by a suitable choice of the viscosity of the liquid target material.
  • the target material can thus advantageously be selected for optimal focusing of the external radiation. If the target material is a highly viscous liquid, the oscillations shown do not form. In this case, the flow structure with an elliptical cross section remains relatively far after the outlet opening 14 and changes into the cylindrical shape without back-oscillation. In this
  • the irradiation takes place in the area of the primary expansion in accordance with the slot-shaped embossing, the flow structure.
  • FIG. 4 illustrates, in a schematic, enlarged view, the cross-sectional area of a concave flow structure 51 that is curved inwards on both sides.
  • the surface 52 has a radius of curvature or radius of curvature that is negative relative to the center of the flow structure 51, so that the thickness ⁇ x is reduced towards the center.
  • the thickness can be reduced by up to 99% from the edge to the center, for example, and can be selected in the range from 500 nm to 500 ⁇ m. Deviating from the illustration in FIG. 4, a shape that is only concavely curved on one side can be provided.
  • the irradiation of the flow structure 51 is preferably carried out perpendicular to the surface 52 at the location of the minimum transverse extent ⁇ x. Depending on the material or the geometry of the radiation, it may be advantageous, alternatively the
  • the cross-sectional shape of the flow structure is determined in particular by the design of the nozzle of the target source.
  • the concave or dumbbell-shaped flow shape according to FIG. 4 can be impressed on the flow structure by a suitable nozzle shape and remains stable over a sufficiently large distance when exiting into a room with negative pressure (in particular vacuum).
  • the nozzle 13 can be formed by a slot-shaped opening 14 at the end of a line for the target material (FIG. 2).
  • FIGS. 5 and 6 show the mouth or outlet opening of a nozzle 13 in the flow direction (from the inside, left partial image) and counter to the flow direction (from the outside, right partial image).
  • a nozzle slot 14a is provided on the inside, which extends over the entire width of the outlet opening 14 and whose slot width decreases in the direction of flow (see the right partial image in FIG. 6).
  • a conical mouth 14b is provided in the flow direction to the nozzle slot 14a, through which the target material 50 exits into the vacuum chamber (see FIG. 6).
  • the flowing target material is first pressed through the nozzle slot 14a, where it converges.
  • the tar- Get material apart at the edges of the cone opening 14b, so that the desired lamella shape of the flow structure results.
  • the first oscillation of the flow structure (see FIG. 3) is influenced by the cone opening 14b.
  • a particular advantage of the nozzle 13 according to FIG. 5 is that the concave shape of the flow structure according to FIG. 4 is formed by the interaction of the nozzle slot 14a and the cone opening 14b.
  • the thickness of the flow structure 51 increases towards the edges (see dashed line in FIG. 6).
  • the nozzle for generating the flattened flow structure is rotatably arranged.
  • the rotatability refers to the axis of the
  • the rotatability can be achieved, for example, by using a rotary holder for the nozzle and a twistable liquid line from the target source.
  • a rigid liquid line can be connected to the nozzle via a rotary coupling.
  • the nozzle is equipped with an adjusting device which comprises, for example, a stepper motor or a piezoelectric drive.
  • FIGS. 7 and 8 illustrate the formation of the flow structure 51 on the impact surface between two primary jets 55, 56 of the target material, which are directed towards one another with two separate nozzles 15, 16 in the vacuum chamber.
  • FIGS. 7A to 7C are based on drawings from the publication by G. Taylor mentioned. According to the figures 7A and 8A, two primary beams with a diameter of z. B. 30 microns at an angle of z. B. 60 ° brought together, so that the flow structure 51 with a thickness of less than 30 microns (z. B. 3 microns) and an expansion of z. B. forms 1 to 2 mm. If, according to FIG. 7B, the meeting of the primary beams 55, '56 at an enlarged cutting angle of z. B.
  • the flow structure 51 is also formed above the impact surface, there is a greater expansion of the layer of the flow structure 51. If the nozzles 15, 16 are oriented opposite to each other by 180 ° according to Figure 8B or 8C, a flow structure results 51 according to FIG. 7C, which can be irradiated laterally horizontally (FIG. 8B) or vertically via a deflecting mirror (FIG. 8C).
  • the location of the combination of the primary jets is selected so that the primary jets have not yet decayed into drops (the distance from the nozzles is less than the drop decay distance).
  • the nozzles 15, 16 can have circular or slot-shaped, in particular elliptical or rectangular cross-sectional areas.
  • the combination of two jets has the advantage that the shape of the flat flow structure in the room is variable. In this case too, the flow structure can be provided at an increased distance from the nozzle 13.
  • the target material preferably used according to the invention in a plasma X-ray source is based on a polymeric hydrocarbon compound which is liquid at room temperature, in particular with at least one ether bond.
  • a building block of such a hydrocarbon compound is illustrated by way of example in FIG. 9. It is emphasized that the implementation of the invention is not limited to the illustrated examples.
  • fluorinated polyethers according to generally also non-fluorinated polymers, mixtures of fluorinated and non-fluorinated polymers or polymers with a low solvent content (less than 20% by volume) can be used.
  • the fluorination can at least partially be replaced by another halogenation, in particular chlorination.
  • the target material shown by way of example in FIG. 9 consists of a large number of building blocks constructed in this way or correspondingly from C, F, 0 and possibly H, so that a low-volatility polymer is formed.
  • the use of the low volatility polymer advantageously reduces the demands on the vacuum system of an X-ray source.
  • the target material forms in particular a partially or perfluorinated polyether (PFPE) or a mixture of several partially fluorinated or perfluorinated polyethers.
  • PFPE partially or perfluorinated polyether
  • a perfluoropolyether is illustrated by way of example in FIG. 10.
  • the PFPE compounds FOMBLIN (registered trademark) and GALDEN (registered trademark) also belong to this class of substances.
  • the x-ray source comprises a target source 10, which is connected to a temperature-controllable vacuum chamber 20, an irradiation device 30 and one
  • the target source 10 comprises a reservoir 11 for the target material, a feed line 12 and a nozzle 13.
  • an actuating device (not shown), which comprises, for example, a pump or a piezoelectric conveying device, target material is fed to the nozzle 13 and from there dispensed in the form of a liquid jet 50 and injected into the vacuum chamber 20.
  • the liquid jet 50 is vertically injected into the vacuum chamber 20 as shown.
  • another beam direction such as a horizontal injection or an injection at a different angle relative to the horizontal, can be provided to implement the invention.
  • the radiation device 30 comprises a radiation source 31 and a radiation optics 32 with which radiation from the radiation source 31 can be focused onto the target material 50.
  • the radiation source 31 is, for example, a laser, the light of which is possibly directed towards the target material with the aid of deflecting mirrors (not shown).
  • an ion source or an electron source can be provided as the radiation device, which is also arranged in the chamber 20.
  • the collecting device 40 comprises a sensor 41 z. B. in the form of a funnel or a capillary, the target material, which has not evaporated under the influence of the radiation, removed from the vacuum chamber and passed into a collecting container 42. Because the liquid polymer is used as the target material, the collected liquid can advantageously be collected in the collecting container 42 without further measures. In order to avoid the risk of backflow of collected target material into the vacuum chamber 20, if necessary, cooling of the collecting container 42 can be provided with a cooling device (not shown) and / or a vacuum pump (not shown).
  • the vacuum chamber 20 comprises a housing 21 with at least one first window 22, through which the target material 50 can be irradiated, and at least one second window 23, through which the generated X-ray radiation emerges.
  • the two te window 23 is optionally provided to decouple the generated X-rays from the vacuum chamber 20 for a specific application. If this is not necessary, the second window 23 can be omitted (see below).
  • the vacuum chamber 20 is also connected to a vacuum device 24, with which a negative pressure is generated in the chamber 20. This negative pressure is preferably below 10 ⁇ 4 mbar.
  • the radiation optics 32 are also arranged in the vacuum chamber 20.
  • the vacuum chamber 20 is equipped with a heating device 60, which comprises one or more thermostats 61 to 63.
  • the housing 21, the sensor 41 and / or the radiation optics 32 can be temperature-controlled with the thermostats. Possibly. the target source 10 can also be tempered.
  • a thermostat includes, for example, a resistance heater known per se.
  • the set with the heater 60 temperature is chosen so that the vapor pressure of, 'which is formed by irradiation of the target material 50 with the irradiation device 30 and in particular of polymeric target material exceeds the gas pressure. This avoids oversaturation of the gas phase in the vacuum chamber.
  • the released polymer remains gaseous and can be pumped out almost quantitatively with the vacuum device 24.
  • the second window 23 consists of a window material transparent to soft X-rays, e.g. B. from beryllium. If the second window 23 is provided, an evacuable processing chamber 26 can be connected, which is connected to a further vacuum device 27. In the processing chamber 26, the x-ray radiation for material processing can be imaged on an object. For example, it is one X-ray lithography device 70 is provided, with which the surface of a semiconductor substrate is irradiated.
  • the spatial separation 'of the X-ray source in the vacuum chamber 20 and the X-ray lithography device 70 in the machining chamber 26 has the advantage that the deposits not exposed of evaporated target material to be machined material.
  • the x-ray lithography device 70 comprises, for example, a filter 71 for selecting the desired x-ray wavelength, a mask 72 and the substrate 73 to be irradiated.
  • imaging optics for example mirrors
  • the X-ray lithography device 70 is arranged in the vacuum chamber 20. In order to avoid precipitation, the device 70 is also connected to a thermostat 64.
  • FIG. 12 further illustrates the use of a double nozzle 15, 16 (see FIG. 8) for generating flow structures according to FIG. 7.
  • the window 22 must be sufficiently stable with respect to the at least partially focused and possibly highly repetitive radiation from the radiation source 31.
  • the target material 50 is guided past the window 22 in a relatively tight manner (for example at a distance of a few cm).
  • a double nozzle can be used instead of the illustrated nozzle 13.
  • sensitive components of the vacuum chamber 20, such as, for example, B. the imaging optics 32 or the device 70 are heated. This embodiment of the invention is illustrated in FIG. 14.
  • the local heating advantageously ensures that the target material released during the irradiation is preferably deposited on the colder walls of the housing 21. The sensitive components that are important for the respective application are protected.
  • a beam or drop of the target material 50 in the form of the flow structure according to the invention is generated with the target source 10.
  • the flow structure 50 is irradiated with the irradiation device 30 in a manner known per se.
  • the radiation is focused with such an intensity that the target material is converted into a plasma state.
  • an energy supply of 100 mJ per irradiation pulse (e.g. per laser shot) is provided.
  • An output power of up to 50 W is achieved at a pulse rate of 10 kHz.
  • soft x-ray radiation is emitted and coupled out through the second window 23 for the respective application.
  • the X-ray radiation has a wavelength range of up to approximately 15 nm.
  • the X-ray source according to the invention is excellently suitable for X-ray microscopic and lithographic applications. Another advantage is the miniaturization of the structure.
  • the device 70 (see FIG. 12) can be arranged in the immediate vicinity of the focus of the irradiation device 30.
  • the collecting device 40 can advantageously be operated without a coolant and without a cooling device. In particular, it is not necessary to provide a so-called cryoprobe or a separator for condensing residual materials.
  • the sensor 41 and the collecting container 42 are connected directly to one another.
  • the residual materials not captured by the collecting device 40 are advantageously volatile components which can be removed from the chamber 20 with the vacuum device 24.
  • the vacuum devices 24, 27 include, for example, rotary vane oil pumps.
  • Preferred applications of the x-ray source according to the invention are in analytical chemistry, in x-ray microscopy, in x-ray lithography and in combination with other spectroscopic measurement methods, such as, for. B. fs spectroscopy.
  • liquid samples for photoelectronic or Photo absorption spectroscopic examinations or corresponding scattering experiments are introduced into the respective examination chamber in accordance with the technique according to the invention.
  • High-energy radiation or particle bombardment can be provided.
  • the liquid layer formed according to the invention can be used as a source for droplets or macro clusters (spray). After a finite distance from the nozzle, the flow structure disintegrates into individual droplets, which are irradiated to generate X-rays.

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • X-Ray Techniques (AREA)

Abstract

L'invention concerne des procédés fondés sur l'utilisation de plasma pour produire des rayons X, comprenant les étapes suivantes : préparer un matériau cible (50) sous forme de configuration d'écoulement (51) libre dans une chambre à vide (20) et exposer le matériau cible (50) à l'action de rayonnements, afin de produire un état du plasma dans lequel les rayons X sont émis. La configuration d'écoulement (51) est conçue de manière que le matériau cible comporte une surface (52) présentant une courbure minimale locale, au moins au point d'exposition à l'action des rayons. L'invention concerne également des dispositifs de mise en oeuvre desdits procédés et en particulier des sources de rayons X utilisées pour produire des rayons X sur la base de plasma.
EP04739766A 2003-06-11 2004-06-09 Production de rayons x selon des procedes fondes sur l'utilisation de plasma, avec un materiau cible en couches Withdrawn EP1632113A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE10326279A DE10326279A1 (de) 2003-06-11 2003-06-11 Plasma-basierte Erzeugung von Röntgenstrahlung mit einem schichtförmigen Targetmaterial
PCT/EP2004/006263 WO2004110112A1 (fr) 2003-06-11 2004-06-09 Production de rayons x selon des procedes fondes sur l'utilisation de plasma, avec un materiau cible en couches

Publications (1)

Publication Number Publication Date
EP1632113A1 true EP1632113A1 (fr) 2006-03-08

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EP04739766A Withdrawn EP1632113A1 (fr) 2003-06-11 2004-06-09 Production de rayons x selon des procedes fondes sur l'utilisation de plasma, avec un materiau cible en couches

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Country Link
US (1) US20110116604A1 (fr)
EP (1) EP1632113A1 (fr)
JP (1) JP2006527469A (fr)
DE (1) DE10326279A1 (fr)
WO (1) WO2004110112A1 (fr)

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US8633459B2 (en) * 2011-03-02 2014-01-21 Cymer, Llc Systems and methods for optics cleaning in an EUV light source
JP6182601B2 (ja) 2012-06-22 2017-08-16 エーエスエムエル ネザーランズ ビー．ブイ． 放射源及びリソグラフィ装置
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Also Published As

Publication number Publication date
DE10326279A1 (de) 2005-01-05
WO2004110112A1 (fr) 2004-12-16
JP2006527469A (ja) 2006-11-30
US20110116604A1 (en) 2011-05-19

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