EP2898756B1 - Euv radiation generating device and operating method therefor - Google Patents

Euv radiation generating device and operating method therefor Download PDF

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Publication number
EP2898756B1
EP2898756B1 EP13765953.8A EP13765953A EP2898756B1 EP 2898756 B1 EP2898756 B1 EP 2898756B1 EP 13765953 A EP13765953 A EP 13765953A EP 2898756 B1 EP2898756 B1 EP 2898756B1
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Prior art keywords
chamber
euv radiation
pressure
intermediate chamber
radiation generating
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German (de)
French (fr)
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EP2898756A1 (en
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Martin Lambert
Andreas Enzmann
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Trumpf Lasersystems for Semiconductor Manufacturing GmbH
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Trumpf Lasersystems for Semiconductor Manufacturing GmbH
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    • 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 present invention relates to an EUV radiation generating apparatus comprising: a vacuum chamber in which a target material can be arranged at a target position for generating EUV radiation, and a beam guiding chamber for guiding a laser beam from a driver laser means in the direction of Target position, an intermediate chamber which is mounted between the vacuum chamber and the beam guiding chamber, a gas-tight the intermediate chamber final window for the laser beam from the beam guiding chamber, as well as the intermediate chamber gas-tight final second window for the exit of the laser beam into the vacuum chamber.
  • the invention also relates to a method of operating such an EUV radiation generating device, comprising: generating EUV radiation by guiding the laser beam to the target material located at the target position.
  • An EUV radiation generating device with a beam guiding device for guiding a laser beam to a target position is also known from US Pat US 2011/0140008 A1 known.
  • the beam guiding device described therein serves to guide laser radiation, which was generated and amplified in a driver laser system.
  • a driver laser a CO 2 laser is usually used, as this allows for certain target materials, for example, in tin, a high conversion efficiency between the input power of the driver laser and the output power of the generated EUV radiation.
  • the beam guiding device guides the laser beam to a focusing element or to a focusing device, which serves to focus the laser beam at the target position.
  • a target material is provided, which passes into a plasma state during the irradiation with the laser beam and thereby emits EUV radiation.
  • a portion of the target material eg, tin
  • the target material eg, tin
  • the laser beam is also reflected by optical elements which have a comparatively rough optical surface, as is caused by tin deposits.
  • an EUV radiation generating device of the type mentioned which has a supply device for supplying a test gas to the intermediate chamber and a leakage monitoring device for monitoring a leakage of the intermediate chamber based on the supplied test gas.
  • the vacuum chamber is sealed off from the environment by the second window. If the second window is destroyed or the seal of the second window is faulty, gas from the environment can flow into the vacuum chamber, since in the vacuum chamber, a lower pressure than in the environment, for example in the beam guide prevails.
  • the window or its seal thus represent potential sources of leakage.
  • a slight leakage affects the environment in the vacuum chamber only as a simple error.
  • a sudden failure of the window with a large leakage leads to the influx of larger amounts of gas into the vacuum environment, which generates a gas flow there, which may possibly pass through the entire vacuum environment. Due to a leaking window, not only gas, but possibly also liquid substances, for example cooling water, which is used to cool the window, can reach the vacuum or the jet guidance chamber.
  • the window is located near the target position with the target material having a portion of the target material in the gas phase that is entrained in a sudden failure of the window of the gas stream. This is particularly problematic because the target material or possibly further entrained contaminants from the EUV radiation generating device in a subsequent in the beam path of the EUV radiation illumination system or
  • Projection system can be transported, which typically have a very clean environment. In the worst case, contamination of this environment with the target material can lead to a total failure of the EUV lithography system, since the target material attaches to the optical elements arranged there and these can possibly no longer be completely cleaned.
  • the loading of the intermediate chamber with a test gas is favorable in order to detect a leakage of the intermediate chamber and thus an insufficient seal between the jet guiding chamber and the vacuum chamber.
  • a suitable inert test gas can reduce the influence of low leakage on the optical elements in the vacuum environment.
  • the detection or monitoring of the leakage can be done, for example, by monitoring the test gas pressure in the intermediate chamber and / or by the detection of the test gas, which is supplied to the intermediate chamber per unit time.
  • the beam-guiding chamber has a higher pressure than the environment of the EUV radiation generating device, with atmospheric pressure (1013 mbar) typically occurring in the vicinity of the EUV jet generating device. Even by a comparatively low overpressure of, for example, 5 mbar or 10 mbar can in the beam-guiding chamber arranged components, eg. Optics, effectively protected from contamination that would otherwise pass from the environment of the EUV radiation generating device in the beam guiding chamber.
  • the supply device has a pressure generating device for acting on the test gas with a feed pressure and a throttle arranged between the pressure generating device and the intermediate chamber.
  • the pressure generating device serves to provide the test gas with a constant (regulated) feed pressure.
  • the test gas passes through the throttle in the intermediate chamber, wherein the test gas pressure in the intermediate chamber in the leak-free operation corresponds to the feed pressure of the pressure generating device, so that no leak gas in the leak-free operation passes through the throttle in the intermediate chamber. If there is a leak, only a small amount of gas flows into the intermediate chamber via the throttle, so that a test gas pressure is established there which is less than the feed pressure.
  • the pressure difference or the gas flow generated by the pressure difference through the throttle are a measure of the leakage of the intermediate chamber.
  • a fixed throttle As a throttle, a fixed throttle is typically used, which has a throttle bore with a constant diameter.
  • the diameter of the orifice defines the sensitivity of the leakage monitoring, with the sensitivity of the decreasing diameter monitoring of the Throttle bore increases.
  • a typical diameter of the throttle bore is in the present application in the order of about 0.1 mm.
  • the supply device has a gas flow sensor for determining a test gas flow fed to the intermediate chamber. As described above, based on the amount of gas flowing through the throttle per unit time (i.e., the check gas flow), the magnitude of the leakage in the intermediate chamber can be deduced.
  • the supply device typically has a supply line for the test gas.
  • the supply line can be selectively provided one or possibly more (small) openings. These orifices make it possible to compensate for changes in pressure caused by changes in the temperature of the test gas that might otherwise cause a leakage of the intermediate chamber to be indicated without actually causing leakage.
  • the EUV radiation generating device comprises at least one pressure sensor for determining a test gas pressure in the intermediate chamber. Based on the sketchgasdrucks in the intermediate chamber, more precisely on the basis of a drop in fürgas horrins, can also be concluded that a leakage of the intermediate chamber. The leakage can be caused by a failure of the first window, the second window and / or the corresponding seals.
  • the EUV radiation generating device has a vacuum generating device for generating an operating pressure in the vacuum chamber.
  • a vacuum generating device typically serves a vacuum pump.
  • the operating pressure in the vacuum chamber in which the target material is disposed is typically on the order of less than 1.0 mbar.
  • a target material delivery device that guides the target material along a predetermined path that crosses the target position.
  • the EUV radiation generating device a focusing device for focusing the laser beam at the target position.
  • the focusing device may have a lens element which transmits the laser radiation and which is formed, for example, from zinc selenide.
  • reflecting optical elements can also be used for focusing the laser beam at the target position.
  • the focusing device is arranged in the vacuum chamber.
  • the beam-guiding chamber can supply a collimated laser beam to the vacuum chamber, which is first focused in the vacuum chamber. It is understood that the focusing can possibly also take place wholly or partly in the beam guiding chamber.
  • At least one of the windows is designed as a plane-parallel plate, wherein preferably both windows are formed as plane-parallel plates. Due to the design as plane-parallel plates, the windows have virtually no optical effect on the typical perpendicular to the plate plane incident laser beam.
  • the material requirement of the material transmitting the laser beam when using plane-parallel plates is low, since the diameter of the plate or disc used must be chosen only slightly larger than the beam diameter of the laser beam, wherein the thickness of the plates can be chosen comparatively small.
  • At least one of the windows is formed from diamond, preferably both windows are formed from diamond.
  • the use of (artificially manufactured) diamond windows has proven to be favorable, since the high laser power (> 1 kW) of the laser beam introduced heat due to the high thermal conductivity of the diamond material can be effectively dissipated.
  • the manufacturing costs for the diamond material are comparatively high, so that the thickness of the window should not be too large.
  • inadequate cooling can result in the thermal destruction of the diamond material (burnup).
  • the beam-guiding chamber has a device for widening the laser beam.
  • the CO 2 laser beam used for generating EUV radiation has a high radiation power (eg greater than 1 kW), so that it is favorable to use comparatively large beam diameters in order not to increase the intensity of the laser radiation as it passes through transmitting optical elements to be let.
  • the use of off-axis parabolic (oid) has proven to be beneficial, as for example in the US 2011/0140008 A1 is described.
  • a further aspect of the invention relates to a method for operating the EUV radiation generating device of the aforementioned type, comprising: monitoring a leakage of the intermediate chamber based on a beaugas horrs in the intermediate chamber and / or by means of a test gas flow of the intermediate chamber supplied test gas.
  • a pressure drop in the intermediate chamber may be detected, indicating destruction of one of the two windows.
  • an immediate shutdown of the EUV lithography system can take place, in which the valves or openings between different assemblies of the EUV lithography system, in which, for example, the illumination system or the projection system are arranged, are closed.
  • a filling or loading of the vacuum environment with an inert gas can take place as a countermeasure.
  • the monitoring of the intermediate chamber for a leak by means of the test gas also makes it possible to perceive a gradual change in the windows, so that countermeasures can be initiated or a warning can already be issued before the windows break or be destroyed.
  • An increased leakage of the intermediate chamber may be due to poor contact between the window and a holder for the window, In particular, serving as a seal bearing surface or contact surface of the socket are generated.
  • Such inadequate mechanical contact may be an indication of a change in the abutment surface and thus an impediment to heat transfer from the window to the material of the fixture which serves as a heat sink for the window.
  • An insufficiently cooled window eg made of diamond, heats up relatively quickly due to absorption and can be destroyed by overheating.
  • a warning can be output to an operator before the error threshold value is reached. In this way, for example, during maintenance work on the EUV radiation generating device, the seal or the socket of the window checked and possibly replaced or repaired.
  • the figure shows an EUV radiation generating device 1, which has a driver laser device 2, a beam guiding chamber 3 and a vacuum chamber 4.
  • a focusing device in the form of a focusing lens 6 is arranged to focus a CO 2 laser beam 5 at a target position Z.
  • the EUV radiation generating device 1 shown in FIG corresponds essentially to the structure, as in the US 2011/0140008 A1 which is incorporated by reference into the contents of this application.
  • On the representation of measuring devices for monitoring the beam path of the laser beam 5 has been omitted for reasons of clarity.
  • the driver laser device 2 comprises a CO 2 beam source and a plurality of amplifiers for generating a laser beam 5 with high radiation power (> 1 kW).
  • high radiation power > 1 kW
  • FIGS US 2011/0140008 A1 directed. From the driver laser device 2, the laser beam 5 is deflected over a plurality of deflecting mirrors 7 to 11 of the beam guiding chamber 3 and a further deflecting mirror 12 in the vacuum chamber 4 to the focusing lens 6, which focuses the laser beam 5 at the target position Z, at the Tin is arranged as a target material 13.
  • the target material 13 is struck by the focused laser beam 5 and thereby converted into a plasma state, which serves to generate EUV radiation 14.
  • the target material 13 is supplied to the target position Z by means of a delivery device (not shown) which guides the target material along a predetermined path crossing the target position 6.
  • a delivery device not shown
  • the target material is also on the US 2011/0140008 A1 directed.
  • a device 15 for increasing a beam diameter of the laser beam 5 which has a first off-axis parabolic mirror 16 with a first, convexly curved reflecting surface and a second off-axis parabolic mirror 17 with a second, concavely curved reflecting beam Surface has.
  • the reflective surfaces of an off-axis parabolic mirror 16, 17 each form the off-axis segments of an (elliptical) paraboloid.
  • the term "off-axis" means that the reflective surfaces do not include the axis of rotation of the paraboloid (and therefore not the apex of the paraboloid).
  • an intermediate chamber 18 is arranged between the beam guiding chamber 3, more precisely its housing, and the vacuum chamber 4.
  • gas-tight final window 19 is mounted, which serves for the entrance of the laser beam 5 of the beam guiding chamber 3.
  • a second window 20 is attached to the vacuum chamber 4 facing housing wall of the intermediate chamber 18 and serves to exit the laser beam 5 from the intermediate chamber 18 in the vacuum chamber. 4
  • a vacuum pump 21 is used to generate an operating pressure p 2 in the vacuum chamber 4, which is in the fine vacuum range (usually at significantly less than 1.0 mbar).
  • the operation of the vacuum chamber 4 under vacuum conditions is required because it would come in a residual gas environment with too high pressure to excessive absorption of the generated EUV radiation 14.
  • the beam-guiding chamber 3 or the interior formed in this is operated at a significantly higher pressure p 1 , which may be, for example, in the order of about 5 mbar above atmospheric pressure (1013 mbar).
  • the beam guiding chamber 3 is thus selectively pressurized with respect to the surroundings of the EUV jet generating device 1 in order to protect the optical elements arranged in the beam guiding chamber 3 from soiling.
  • the pressure difference between the beam guiding chamber 3 and the vacuum chamber 4 the gas from the beam guiding chamber 3 in the interior of the vacuum chamber 4 arrive and there Entrain residues or deposits of the target material 13 and transport them to other (not shown) assemblies of the EUV lithography system.
  • These assemblies are essentially an illumination system for illuminating a structure-bearing mask and an imaging system for imaging the structure on the mask onto a photosensitive substrate (wafer).
  • the further assemblies or the optical elements arranged there can be contaminated by the target material, which may lead to a total failure of the EUV lithography system can lead.
  • cooling water can also enter the interior of the vacuum chamber 4 and carry along therewith residues or deposits of the target material 13 and transport these residues to further assemblies (not illustrated) of the EUV lithography system.
  • a supply means 23 for a test gas 24 is provided, which has a test gas reservoir 25 as a test gas supply device containing the test gas 24, for example nitrogen or argon, and this with a constant (possibly. regulated) feed pressure p 0 provides.
  • the test gas 24 is supplied via a supply line 27 of the intermediate chamber 18.
  • a fixed throttle 26 is provided in the supply line with a throttle bore which limits the test gas flow into the intermediate chamber 18.
  • the pressure p in the intermediate chamber 18 coincides with the feed pressure p 0 and no test gas 24 flows through the feed line 27 into the intermediate chamber 18.
  • the pressure sensor 28 measures the pressure the fürgastiks p in the intermediate chamber 18 measured test gas pressure p is thus consistent with the feed pressure p 0 match.
  • the feed pressure p 0 (and thus the excgastik p in leak-free case) is greater than the pressure in the beam-guiding chamber 3 and greater than the operating pressure p 2 of the vacuum chamber 4 and may for example be about 1023 mbar.
  • the test gas pressure p decreases compared to the feed pressure p 0 .
  • This can be evaluated by a leakage monitoring device 29 which is in signal communication with the pressure sensor 28 for this purpose.
  • a signaling connection to the supply device 23 is not required if the leakage detection device 29 has access to a memory device in which the numerical value for the fixed or fixed to a fixed value feed pressure p 0 is stored. It goes without saying that the leakage monitoring device 29 in the figure is only attached to the intermediate chamber 18 by way of example and can also be arranged elsewhere in the EUV radiation generating device 1.
  • the leakage monitoring device 29 can conclude from the destruction of one of the windows 19, 20 by a sudden, strong pressure drop in the intermediate chamber 18, by comparing the measured fürgastik p in the intermediate chamber 18 with an error threshold value for für für p becomes. If the test gas pressure p falls below the error threshold, countermeasures are promptly initiated in order to protect the optical elements arranged in the vacuum chamber 4 or in further vacuum chambers connected therewith from contamination (see above).
  • the leakage monitoring device 29 reacts with a suitably selected diameter of the throttle bore (for example, about 0.1 mm) very sensitive to small leaks of the intermediate chamber 18, as for example in an incomplete sealing of the windows 19, 20 against the housing of the intermediate Chamber 18, more precisely against a holder provided there or a version may occur.
  • the detection of small amounts of leakage can provide an indication that undefined states are present on the components of the beam-guiding chamber 3.
  • Such an early warning of a possible destruction of the windows 19, 20 is particularly advantageous when using diamond as the window material, since a replacement required by the erosion or destruction of a diamond window 19, 20 is associated with considerable costs ,
  • the use of diamond as a window material is advantageous because of its high thermal conductivity.
  • test gas flow dv / dt of the test gas 24 flowing through the feed line 27 can also take place with the aid of a gas flow sensor 30.
  • the test gas flow dv / dt disappears without leakage, since in this case the feed pressure p 0 and the pressure p in the intermediate chamber 18 coincide.
  • the test gas flow increases with decreasing test gas pressure p in the intermediate chamber 18 (corresponding to an increasing pressure difference between the feed pressure p 0 and the educagas horr p in the intermediate chamber 18).
  • the test gas flow dv / dt can also be compared by the leakage monitoring device 29 with an error threshold value or with a warning threshold value in order to detect an error case or to issue a warning.
  • Changes in the pressure p in the intermediate chamber 18 can also be caused by temperature changes of the test gas 24. This could possibly lead to an error message, without actually occurring a leakage in the intermediate chamber 18.
  • a leak or a (small) opening can be introduced into the supply line 27 in a targeted manner, via which the test gas 24 communicates with the environment for pressure equalization.
  • the reliability and reliability of the EUV radiation generating device can be significantly increased. It is understood that for leakage monitoring, if necessary, the supply of a test gas can be dispensed with by monitoring the gas pressure in the intermediate chamber directly by means of a pressure sensor.

Description

Die vorliegende Erfindung betrifft eine EUV-Strahlungserzeugungsvorrichtung, umfassend: eine Vakuum-Kammer, in der zur Erzeugung von EUV-Strahlung ein Target-Material an einer Zielposition anordenbar ist, sowie eine Strahlführungs-Kammer zur Führung eines Laserstrahls von einer Treiberlasereinrichtung in Richtung auf die Zielposition, eine Zwischen-Kammer, die zwischen der Vakuum-Kammer und der Strahlführungs-Kammer angebracht ist, ein die Zwischen-Kammer gasdicht abschließendes erstes Fenster zum Eintritt des Laserstrahls von der Strahlführungs-Kammer, sowie ein die Zwischen-Kammer gasdicht abschließendes zweites Fenster zum Austritt des Laserstrahls in die Vakuum-Kammer. Die Erfindung betrifft auch ein Verfahren zum Betreiben einer solchen EUV-Strahlungserzeugungsvorrichtung, umfassend: Erzeugen von EUV-Strahlung durch Führen des Laserstrahls zu dem an der Zielposition angeordneten Target-Material.The present invention relates to an EUV radiation generating apparatus comprising: a vacuum chamber in which a target material can be arranged at a target position for generating EUV radiation, and a beam guiding chamber for guiding a laser beam from a driver laser means in the direction of Target position, an intermediate chamber which is mounted between the vacuum chamber and the beam guiding chamber, a gas-tight the intermediate chamber final window for the laser beam from the beam guiding chamber, as well as the intermediate chamber gas-tight final second window for the exit of the laser beam into the vacuum chamber. The invention also relates to a method of operating such an EUV radiation generating device, comprising: generating EUV radiation by guiding the laser beam to the target material located at the target position.

Eine EUV-Strahlungserzeugungsvorrichtung der eingangs genannten Art ist aus der US 2010/0024980 A1 bekannt geworden.An EUV radiation generating device of the aforementioned type is known from US 2010/0024980 A1 known.

Eine EUV-Strahlungserzeugungsvorrichtung mit einer Strahlführungseinrichtung zur Führung eines Laserstrahls an eine Zielposition ist auch aus der US 2011/0140008 A1 bekannt geworden. Die dort beschriebene Strahlführungseinrichtung dient zur Führung von Laserstrahlung, die in einem Treiberlasersystem erzeugt und verstärkt wurde. Als Treiberlaser wird in der Regel ein CO2-Laser verwendet, da dieser bei bestimmten Target-Materialien, z.B. bei Zinn, eine hohe Konversionseffizienz zwischen der Eingangsleistung des Treiberlasers und der Ausgangsleistung der erzeugten EUV-Strahlung ermöglicht. Die Strahlführungseinrichtung führt den Laserstrahl zu einem fokussierenden Element bzw. zu einer Fokussiereinrichtung, welche dazu dient, den Laserstrahl an der Zielposition zu fokussieren. An der Zielposition wird ein Target-Material bereitgestellt, welches bei der Bestrahlung mit dem Laserstrahl in einen Plasma-Zustand übergeht und hierbei EUV-Strahlung emittiert.An EUV radiation generating device with a beam guiding device for guiding a laser beam to a target position is also known from US Pat US 2011/0140008 A1 known. The beam guiding device described therein serves to guide laser radiation, which was generated and amplified in a driver laser system. As a driver laser, a CO 2 laser is usually used, as this allows for certain target materials, for example, in tin, a high conversion efficiency between the input power of the driver laser and the output power of the generated EUV radiation. The beam guiding device guides the laser beam to a focusing element or to a focusing device, which serves to focus the laser beam at the target position. At the target position, a target material is provided, which passes into a plasma state during the irradiation with the laser beam and thereby emits EUV radiation.

Bei der Bestrahlung mit dem Laserstrahl wird typischer Weise ein Teil des Target-Materials (z.B. Zinn) verdampft, der sich auf den optischen Oberflächen von optischen Elementen ablagern kann, die in der Nähe der Zielposition angeordnet sind. Der Laserstrahl wird aufgrund seiner hohen Wellenlänge von z.B. ca. 10,6 µm (bei Verwendung eines CO2-Lasers) auch von optischen Elementen reflektiert, die eine vergleichsweise raue optische Oberfläche aufweisen, wie sie durch Zinn-Ablagerungen hervorgerufen wird. Bei optischen Elementen, die zur Reflexion der an der Zielposition erzeugten EUV-Strahlung dienen, ist dies in der Regel nicht der Fall, d.h. Ablagerungen von kontaminierenden Stoffen an diesen optischen Elementen führen typischer Weise zu einer signifikanten Verringerung der Reflektivität für die verwendete EUV-Strahlung, so dass die in der Vakuum-Kammer bzw. in dieser nachgelagerten Baugruppen, beispielsweise einem Beleuchtungssystem und einer einem Projektionssystem angeordneten optischen Elemente vor kontaminierenden Stoffen, insbesondere vor Ablagerungen des Target-Materials, geschützt werden sollten.Upon irradiation with the laser beam, a portion of the target material (eg, tin) is typically evaporated, which may deposit on the optical surfaces of optical elements located near the target position. Due to its high wavelength of, for example, about 10.6 μm (when using a CO 2 laser), the laser beam is also reflected by optical elements which have a comparatively rough optical surface, as is caused by tin deposits. For optical elements which serve to reflect the EUV radiation generated at the target position, this is generally not the case, ie deposits of contaminants on these optical elements typically lead to a significant reduction in the reflectivity for the EUV radiation used so that in the vacuum chamber or in this downstream modules, such as a lighting system and a projection system arranged optical elements should be protected from contaminants, especially against deposits of the target material.

Aufgabe der ErfindungObject of the invention

Es ist die Aufgabe der vorliegenden Erfindung, eine EUV-Strahlungserzeugungsvorrichtung der eingangs genannten Art und ein Verfahren zum Betrieb der Strahlungserzeugungsvorrichtung dahingehend weiterzubilden, dass die Betriebssicherheit der EUV-Strahlungserzeugungsvorrichtung erhöht wird.It is the object of the present invention to further develop an EUV radiation generating device of the type mentioned in the introduction and a method for operating the radiation generating device in such a way that the operational safety of the EUV radiation generating device is increased.

Gegenstand der ErfindungSubject of the invention

Diese Aufgabe wird erfindungsgemäß gelöst durch eine EUV-Strahlungserzeugungsvorrichtung der eingangs genannten Art, die eine Zuführungseinrichtung zur Zuführung eines Prüfgases zur Zwischen-Kammer sowie eine Leckage-Überwachungseinrichtung zum Überwachen einer Leckage der Zwischen-Kammer anhand des zugeführten Prüfgases aufweist.This object is achieved by an EUV radiation generating device of the type mentioned, which has a supply device for supplying a test gas to the intermediate chamber and a leakage monitoring device for monitoring a leakage of the intermediate chamber based on the supplied test gas.

Die Vakuum-Kammer wird durch das zweite Fenster dichtend von der Umgebung abgetrennt. Wird das zweite Fenster zerstört oder ist die Dichtung des zweiten Fensters fehlerhaft, kann Gas aus der Umgebung in die Vakuum-Kammer einströmen, da in der Vakuum-Kammer ein geringerer Druck als in der Umgebung, beispielsweise in der Strahlführung, herrscht. Das Fenster bzw. dessen Abdichtung stellen somit potentielle Leckagequellen dar. Eine geringe Leckage wirkt sich auf die Umgebung in der Vakuum-Kammer nur als einfacher Fehler aus. Ein plötzliches Versagen des Fensters mit einer großen Leckage führt zum Einströmen größerer Gasmengen in die Vakuum-Umgebung, was dort einen Gasstrom erzeugt, der ggf. die gesamte Vakuum-Umgebung durchlaufen kann. Aufgrund eines undichten Fensters kann nicht nur Gas, sondern es können ggf. auch flüssige Stoffe, bspw. Kühlwasser, welches zur Kühlung des Fensters verwendet wird, in die Vakuum- bzw. in die Strahlführungs-Kammer gelangen.The vacuum chamber is sealed off from the environment by the second window. If the second window is destroyed or the seal of the second window is faulty, gas from the environment can flow into the vacuum chamber, since in the vacuum chamber, a lower pressure than in the environment, for example in the beam guide prevails. The window or its seal thus represent potential sources of leakage. A slight leakage affects the environment in the vacuum chamber only as a simple error. A sudden failure of the window with a large leakage leads to the influx of larger amounts of gas into the vacuum environment, which generates a gas flow there, which may possibly pass through the entire vacuum environment. Due to a leaking window, not only gas, but possibly also liquid substances, for example cooling water, which is used to cool the window, can reach the vacuum or the jet guidance chamber.

Das Fenster befindet sich in der Nähe der Zielposition mit dem Target-Material, an dem sich ein Anteil des Target-Materials in der Gasphase befindet, der bei einem plötzlichen Versagen des Fensters von dem Gasstrom mitgerissen wird. Dies ist insbesondere deshalb problematisch, weil das Target-Material oder ggf. weitere mitgerissene kontaminierende Stoffe von der EUV-Strahlungserzeugungsvorrichtung in ein im Strahlweg der EUV-Strahlung nachfolgendes Beleuchtungssystem bzw.The window is located near the target position with the target material having a portion of the target material in the gas phase that is entrained in a sudden failure of the window of the gas stream. This is particularly problematic because the target material or possibly further entrained contaminants from the EUV radiation generating device in a subsequent in the beam path of the EUV radiation illumination system or

Projektionssystem transportiert werden können, die typischer Weise eine sehr saubere Umgebung aufweisen. Eine Verunreinigung dieser Umgebung mit dem Target-Material kann im schlimmsten Fall zu einem Totalausfall der EUV-Lithographieanlage führen, da sich das Target-Material an den dort angeordneten optischen Elementen anlagert und diese ggf. nicht mehr vollständig gereinigt werden können.Projection system can be transported, which typically have a very clean environment. In the worst case, contamination of this environment with the target material can lead to a total failure of the EUV lithography system, since the target material attaches to the optical elements arranged there and these can possibly no longer be completely cleaned.

Um bei einem plötzlichen Versagen des ersten Fensters den Eintritt von größeren Gasmengen in die Vakuum-Kammer zu verhindern, wird vorgeschlagen, ein weiteres (erstes) Fenster zu verwenden, welches zu dem zweiten Fenster in Reihe geschaltet ist. Gibt das zweite Fenster nach, kann nur das in dem Zwischenraum vorhandene (kleine) Gasvolumen in die Vakuum-Kammer gelangen, was aufgrund des deutlich größeren Volumens der Vakuum-Kammer nur zu einer vergleichsweise geringfügigen Beeinträchtigung der EUV-Lithographieanlage führt. Da ein gleichzeitiger Ausfall beider Fenster äußerst unwahrscheinlich ist, kann mit Hilfe der Zwischen-Kammer die Betriebssicherheit der EUV-Strahlungserzeugungsvorrichtung deutlich erhöht werden.In order to prevent the entry of larger amounts of gas into the vacuum chamber in the event of a sudden failure of the first window, it is proposed to use a further (first) window, which is connected in series with the second window. If the second window yields, only the (small) gas volume present in the intermediate space can enter the vacuum chamber, which only leads to a comparatively slight impairment of the EUV lithography system due to the significantly larger volume of the vacuum chamber. Since a simultaneous failure of both windows is extremely unlikely, the reliability of the EUV radiation generating device can be significantly increased by means of the intermediate chamber.

Die Beaufschlagung der Zwischen-Kammer mit einem Prüfgas, insbesondere mit einem inerten Gas, beispielsweise mit Stickstoff oder Argon, ist günstig, um eine Leckage der Zwischen-Kammer und damit eine unzureichende Abdichtung zwischen der Strahlführungs-Kammer und der Vakuum-Kammer zu detektieren. Zudem kann durch die Verwendung eines geeigneten inerten Prüfgases der Einfluss, den eine geringe Leckage auf die optischen Elemente in der Vakuum-Umgebung hat, vermindert werden. Die Detektion bzw. Überwachung der Leckage kann beispielsweise durch die Überwachung des Prüfgasdrucks in der Zwischen-Kammer und/oder durch die Detektion der Prüfgasmenge erfolgen, die der Zwischen-Kammer pro Zeiteinheit zugeführt wird.The loading of the intermediate chamber with a test gas, in particular with an inert gas, for example with nitrogen or argon, is favorable in order to detect a leakage of the intermediate chamber and thus an insufficient seal between the jet guiding chamber and the vacuum chamber. In addition, the use of a suitable inert test gas can reduce the influence of low leakage on the optical elements in the vacuum environment. The detection or monitoring of the leakage can be done, for example, by monitoring the test gas pressure in the intermediate chamber and / or by the detection of the test gas, which is supplied to the intermediate chamber per unit time.

Bei einer Ausführungsform weist die Strahlführungs-Kammer einen höheren Druck auf als die Umgebung der EUV-Strahlungserzeugungsvorrichtung, wobei in der Umgebung der EUV-Strahlerzeugungsvorrichtung typischer Weise Atmosphärendruck (1013 mbar) herrscht. Schon durch einen vergleichsweise geringen Überdruck von z.B. 5 mbar oder 10 mbar können in der Strahlführungs-Kammer angeordnete Bauteile, bspw. Optiken, wirksam vor Verschmutzungen geschützt werden, die ansonsten aus der Umgebung der EUV-Strahlungserzeugungsvorrichtung in die Strahlführungs-Kammer gelangen würden.In one embodiment, the beam-guiding chamber has a higher pressure than the environment of the EUV radiation generating device, with atmospheric pressure (1013 mbar) typically occurring in the vicinity of the EUV jet generating device. Even by a comparatively low overpressure of, for example, 5 mbar or 10 mbar can in the beam-guiding chamber arranged components, eg. Optics, effectively protected from contamination that would otherwise pass from the environment of the EUV radiation generating device in the beam guiding chamber.

Bei einer Weiterbildung ist die Zuführungseinrichtung zur Erzeugung eines Prüfgasdrucks in der Zwischen-Kammer ausgebildet, der größer ist als ein Druck in der Strahlführungs-Kammer und ein Betriebsdruck in der Vakuum-Kammer. Die Erzeugung eines Überdrucks gegenüber dem Druck in der Strahlführungs-Kammer und dem - deutlich kleineren - Betriebsdruck in der Vakuum-Kammer hat sich als vorteilhaft erwiesen, da auf diese Weise dem Eindringen von Fremdstoffen insbesondere aus der Strahlführungs-Kammer in die Zwischen-Kammer entgegen gewirkt werden kann.In a further development, the supply device for generating a Prüfgasdrucks is formed in the intermediate chamber, which is greater than a pressure in the beam-guiding chamber and an operating pressure in the vacuum chamber. The generation of an overpressure relative to the pressure in the jet-guiding chamber and the - much smaller - operating pressure in the vacuum chamber has proved to be advantageous, since in this way the intrusion of foreign substances in particular from the beam-guiding chamber into the intermediate chamber opposite can be worked.

Bei einer Weiterbildung weist die Zuführungseinrichtung eine Druckerzeugungseinrichtung zur Beaufschlagung des Prüfgases mit einem Speisedruck sowie eine zwischen der Druckerzeugungseinrichtung und der Zwischen-Kammer angeordnete Drossel auf. Die Druckerzeugungseinrichtung dient zur Bereitstellung des Prüfgases mit einem konstanten (geregelten) Speisedruck. Das Prüfgas gelangt über die Drossel in die Zwischen-Kammer, wobei der Prüfgasdruck in der Zwischen-Kammer im leckagefreien Betrieb dem Speisedruck der Druckerzeugungseinrichtung entspricht, so dass im leckagefreien Betrieb kein Prüfgas über die Drossel in die Zwischen-Kammer gelangt. Liegt eine Leckage vor, strömt über die Drossel nur eine geringfügige Gasmenge in die Zwischen-Kammer nach, so dass sich dort ein Prüfgasdruck einstellt, der kleiner ist als der Speisedruck. Die Druckdifferenz bzw. die die durch die Druckdifferenz erzeugte Gasströmung durch die Drossel stellen ein Maß für die Leckage der Zwischen-Kammer dar.In a further development, the supply device has a pressure generating device for acting on the test gas with a feed pressure and a throttle arranged between the pressure generating device and the intermediate chamber. The pressure generating device serves to provide the test gas with a constant (regulated) feed pressure. The test gas passes through the throttle in the intermediate chamber, wherein the test gas pressure in the intermediate chamber in the leak-free operation corresponds to the feed pressure of the pressure generating device, so that no leak gas in the leak-free operation passes through the throttle in the intermediate chamber. If there is a leak, only a small amount of gas flows into the intermediate chamber via the throttle, so that a test gas pressure is established there which is less than the feed pressure. The pressure difference or the gas flow generated by the pressure difference through the throttle are a measure of the leakage of the intermediate chamber.

Als Drossel wird typischer Weise eine Fest-Drossel verwendet, die eine Drosselbohrung mit konstantem Durchmesser aufweist. Der Durchmesser der Drosselbohrung legt die Sensitivität der Leckageüberwachung fest, wobei die Empfindlichkeit der Überwachung mit abnehmendem Durchmesser der Drosselbohrung zunimmt. Ein typischer Durchmesser der Drosselbohrung liegt bei der vorliegenden Anwendung in der Größenordnung von ca. 0,1 mm.As a throttle, a fixed throttle is typically used, which has a throttle bore with a constant diameter. The diameter of the orifice defines the sensitivity of the leakage monitoring, with the sensitivity of the decreasing diameter monitoring of the Throttle bore increases. A typical diameter of the throttle bore is in the present application in the order of about 0.1 mm.

Bei einer Weiterbildung weist die Zuführungseinrichtung einen Gasfluss-Sensor zur Bestimmung eines der Zwischen-Kammer zugeführten Prüfgas-Flusses auf. Wie weiter oben dargestellt wurde, kann anhand der Größe der pro Zeiteinheit durch die Drossel strömenden Gasmenge (d.h. des Prüfgas-Flusses) auf die Größe der Leckage in der Zwischen-Kammer geschlossen werden.In a development, the supply device has a gas flow sensor for determining a test gas flow fed to the intermediate chamber. As described above, based on the amount of gas flowing through the throttle per unit time (i.e., the check gas flow), the magnitude of the leakage in the intermediate chamber can be deduced.

Die Zuführungseinrichtung weist typischer Weise eine Zuführungsleitung für das Prüfgas auf. In der Zuführungsleitung können gezielt eine oder ggf. mehrere (kleine) Öffnungen vorgesehen sein. Diese Öffnung(en) ermöglichen es, durch Temperaturänderungen des Prüfgases hervorgerufene Druckänderungen auszugleichen, die ansonsten ggf. dazu führen könnten, dass eine Leckage der Zwischen-Kammer angezeigt wird, ohne dass tatsächlich eine Leckage vorliegt.The supply device typically has a supply line for the test gas. In the supply line can be selectively provided one or possibly more (small) openings. These orifices make it possible to compensate for changes in pressure caused by changes in the temperature of the test gas that might otherwise cause a leakage of the intermediate chamber to be indicated without actually causing leakage.

Bei einer weiteren Weiterbildung umfasst die EUV-Strahlungserzeugungsvorrichtung mindestens einen Drucksensor zur Bestimmung eines Prüfgasdrucks in der Zwischen-Kammer. Anhand des Prüfgasdrucks in der Zwischen-Kammer, genauer gesagt anhand eines Abfalls des Prüfgasdrucks, kann ebenfalls auf eine Leckage der Zwischen-Kammer geschlossen werden. Die Leckage kann durch ein Versagen des ersten Fensters, des zweiten Fensters und/oder der entsprechenden Dichtungen zu Stande kommen.In a further development, the EUV radiation generating device comprises at least one pressure sensor for determining a test gas pressure in the intermediate chamber. Based on the Prüfgasdrucks in the intermediate chamber, more precisely on the basis of a drop in Prüfgasdrucks, can also be concluded that a leakage of the intermediate chamber. The leakage can be caused by a failure of the first window, the second window and / or the corresponding seals.

Bei einer Weiterbildung weist die EUV-Strahlungserzeugungsvorrichtung eine Vakuum-Erzeugungseinrichtung zur Erzeugung eines Betriebsdrucks in der Vakuum-Kammer auf. Als Vakuum-Erzeugungseinrichtung dient typischer Weise eine Vakuum-Pumpe. Der Betriebsdruck in der Vakuum-Kammer, in welcher das Target-Material angeordnet ist, liegt typischer Weise in der Größenordnung von weniger als 1,0 mbar. In der Vakuum-Kammer ist eine Bereitstellungseinrichtung für das Target-Material vorgesehen, welche das Target-Material entlang eines vorgegebenen Pfades führt, der die Zielposition kreuzt.In a development, the EUV radiation generating device has a vacuum generating device for generating an operating pressure in the vacuum chamber. As a vacuum generating device typically serves a vacuum pump. The operating pressure in the vacuum chamber in which the target material is disposed is typically on the order of less than 1.0 mbar. Provided in the vacuum chamber is a target material delivery device that guides the target material along a predetermined path that crosses the target position.

Bei einer weiteren Ausführungsform weist die EUV-Strahlungserzeugungsvorrichtung eine Fokussiereinrichtung zur Fokussierung des Laserstrahls an der Zielposition auf. Die Fokussiereinrichtung kann ein Linsenelement aufweisen, welches die Laserstrahlung transmittiert und welches beispielsweise aus Zinkselenid gebildet ist. Zusätzlich oder alternativ zu transmittierenden optischen Elementen können für die Fokussierung des Laserstrahls an der Zielposition auch reflektierende optische Elemente verwendet werden.In another embodiment, the EUV radiation generating device a focusing device for focusing the laser beam at the target position. The focusing device may have a lens element which transmits the laser radiation and which is formed, for example, from zinc selenide. In addition to or as an alternative to transmitting optical elements, reflecting optical elements can also be used for focusing the laser beam at the target position.

In einer Weiterbildung ist die Fokussiereinrichtung in der Vakuum-Kammer angeordnet. In diesem Fall kann die Strahlführungs-Kammer der Vakuum-Kammer einen kollimierten Laserstrahl zuführen, welcher erst in der Vakuum-Kammer fokussiert wird. Es versteht sich, dass die Fokussierung ggf. auch ganz oder teilweise in der Strahlführungs-Kammer erfolgen kann.In a further development, the focusing device is arranged in the vacuum chamber. In this case, the beam-guiding chamber can supply a collimated laser beam to the vacuum chamber, which is first focused in the vacuum chamber. It is understood that the focusing can possibly also take place wholly or partly in the beam guiding chamber.

Bei einer weiteren Ausführungsform ist mindestens eines der Fenster als planparallele Platte ausgebildet, wobei bevorzugt beide Fenster als planparallele Platten ausgebildet sind. Durch die Ausbildung als planparallele Platten haben die Fenster praktisch keine optische Wirkung auf den typischer Weise senkrecht zur Platten-Ebene auftreffenden Laserstrahl. Auch ist der Materialbedarf des den Laserstrahl transmittierenden Materials bei der Verwendung von planparallelen Platten gering, da der Durchmesser der verwendeten Platte bzw. Scheibe nur unwesentlich größer gewählt werden muss als der Strahldurchmesser des Laserstrahls, wobei die Dicke der Platten vergleichsweise gering gewählt werden kann.In a further embodiment, at least one of the windows is designed as a plane-parallel plate, wherein preferably both windows are formed as plane-parallel plates. Due to the design as plane-parallel plates, the windows have virtually no optical effect on the typical perpendicular to the plate plane incident laser beam. The material requirement of the material transmitting the laser beam when using plane-parallel plates is low, since the diameter of the plate or disc used must be chosen only slightly larger than the beam diameter of the laser beam, wherein the thickness of the plates can be chosen comparatively small.

Bei einer Weiterbildung ist mindestens eines der Fenster aus Diamant gebildet, bevorzugt sind beide Fenster aus Diamant gebildet. Die Verwendung von Fenstern aus (künstlich hergestelltem) Diamant hat sich als günstig erwiesen, da die durch die hohe Laserleistung (> 1 kW) des Laserstrahls eingebrachte Wärme aufgrund der hohen Wärmeleitfähigkeit des Diamant-Materials effektiv abgeführt werden kann. Allerdings sind die Herstellungskosten für das Diamant-Material vergleichsweise hoch, so dass die Dicke des Fensters nicht zu groß gewählt werden sollte. Zudem kann auch bei der Verwendung eines Fensters mit vergleichsweise großer Dicke beispielsweise eine unzureichende Kühlung die thermische Zerstörung des Diamant-Materials (Abbrand) zur Folge haben.In a further development, at least one of the windows is formed from diamond, preferably both windows are formed from diamond. The use of (artificially manufactured) diamond windows has proven to be favorable, since the high laser power (> 1 kW) of the laser beam introduced heat due to the high thermal conductivity of the diamond material can be effectively dissipated. However, the manufacturing costs for the diamond material are comparatively high, so that the thickness of the window should not be too large. In addition, even when using a window with a comparatively large thickness, for example, inadequate cooling can result in the thermal destruction of the diamond material (burnup).

In einer weiteren Ausführungsform weist die Strahlführungs-Kammer eine Einrichtung zur Aufweitung des Laserstrahls auf. Die zur Erzeugung von EUV-Strahlung verwendete CO2-Laserstrahlun weist eine hohe Strahlungsleistung (z.B. größer 1 kW) auf, so dass es günstig ist, vergleichsweise große Strahldurchmesser zu verwenden, um die Intensität der Laserstrahlung beim Durchtritt durch transmittierende optische Elemente nicht zu groß werden zu lassen. Zur Strahlaufweitung von Laserstrahlung mit großen Strahldurchmessern hat sich die Verwendung von off-axis Parabol(oid)-Spiegeln als günstig erwiesen, wie dies beispielsweise in der US 2011/0140008 A1 beschrieben ist.In a further embodiment, the beam-guiding chamber has a device for widening the laser beam. The CO 2 laser beam used for generating EUV radiation has a high radiation power (eg greater than 1 kW), so that it is favorable to use comparatively large beam diameters in order not to increase the intensity of the laser radiation as it passes through transmitting optical elements to be let. For the beam expansion of laser radiation with large beam diameters, the use of off-axis parabolic (oid) has proven to be beneficial, as for example in the US 2011/0140008 A1 is described.

Ein weiterer Aspekt der Erfindung betrifft ein Verfahren zum Betreiben der EUV-Strahlungserzeugungsvorrichtung der eingangs genannten Art, umfassend: Überwachen einer Leckage der Zwischen-Kammer anhand eines Prüfgasdrucks in der Zwischen-Kammer und/oder anhand eines Prüfgas-Flusses des der Zwischen-Kammer zugeführten Prüfgases.A further aspect of the invention relates to a method for operating the EUV radiation generating device of the aforementioned type, comprising: monitoring a leakage of the intermediate chamber based on a Prüfgasdrucks in the intermediate chamber and / or by means of a test gas flow of the intermediate chamber supplied test gas.

Wie weiter oben beschrieben wurde, kann durch Vergleichen des Prüfgasdrucks bzw. des Prüfgas-Flusses mit einem jeweiligen Fehler-Schwellwert ein Druckabfall in der Zwischen-Kammer detektiert werden, der auf eine Zerstörung eines der beiden Fenster hinweist. Beim Erreichen des Fehler-Schwellwerts kann eine Sofortabschaltung der EUV-Lithographieanlage erfolgen, bei welcher die Ventile bzw. Öffnungen zwischen unterschiedlichen Baugruppen der EUV-Lithographieanlage, in denen beispielsweise das Beleuchtungssystem oder das Projektionssystem angeordnet sind, verschlossen werden. Alternativ oder zusätzlich kann als Gegenmaßnahme auch eine Befüllung bzw. Beaufschlagung der Vakuum-Umgebung mit einem inerten Gas erfolgen.As described above, by comparing the test gas pressure and the test gas flow, respectively, with a respective error threshold, a pressure drop in the intermediate chamber may be detected, indicating destruction of one of the two windows. Upon reaching the error threshold, an immediate shutdown of the EUV lithography system can take place, in which the valves or openings between different assemblies of the EUV lithography system, in which, for example, the illumination system or the projection system are arranged, are closed. Alternatively or additionally, a filling or loading of the vacuum environment with an inert gas can take place as a countermeasure.

Die Überwachung der Zwischen-Kammer auf eine Leckage mittels des Prüfgases ermöglicht es auch, eine schleichende Veränderung an den Fenstern wahrzunehmen, so dass Gegenmaßnahmen eingeleitet oder eine Warnung bereits ausgegeben werden kann, bevor es zum Bruch bzw. zur Zerstörung der Fenster kommt. Eine erhöhte Leckage der Zwischen-Kammer kann durch einen schlechten Kontakt zwischen dem Fenster und einer Fassung bzw. Halterung für das Fenster, insbesondere einer als Dichtung dienenden Auflagefläche bzw. Anlagefläche der Fassung erzeugt werden. Ein solcher unzureichender mechanischer Kontakt kann ein Hinweis auf eine Veränderung der Anlagefläche und damit auf eine Behinderung des Wärmetransports vom Fenster in das Material der Fassung bzw. Halterung sein, welches als Wärmesenke für das Fenster dient. Ein unzureichend gekühltes Fenster, z.B. aus Diamant, erwärmt sich aufgrund der Absorption relativ schnell und kann durch Überhitzen zerstört werden.The monitoring of the intermediate chamber for a leak by means of the test gas also makes it possible to perceive a gradual change in the windows, so that countermeasures can be initiated or a warning can already be issued before the windows break or be destroyed. An increased leakage of the intermediate chamber may be due to poor contact between the window and a holder for the window, In particular, serving as a seal bearing surface or contact surface of the socket are generated. Such inadequate mechanical contact may be an indication of a change in the abutment surface and thus an impediment to heat transfer from the window to the material of the fixture which serves as a heat sink for the window. An insufficiently cooled window, eg made of diamond, heats up relatively quickly due to absorption and can be destroyed by overheating.

Wird der Prüfgasdruck bzw. der Prüfgas-Fluss mit einem jeweiligen Warn-Schwellwert verglichen und wird der Warn-Schwellwert erreicht, kann eine Warnung an einen Bediener ausgegeben werden, bevor der Fehler-Schwellwert erreicht ist. Auf diese Weise kann beispielsweise bei Wartungsarbeiten an der EUV-Strahlungserzeugungsvorrichtung die Dichtung bzw. die Fassung des Fensters überprüft und ggf. ausgetauscht oder repariert werden.If the test gas pressure or the test gas flow is compared with a respective warning threshold value and the warning threshold value is reached, a warning can be output to an operator before the error threshold value is reached. In this way, for example, during maintenance work on the EUV radiation generating device, the seal or the socket of the window checked and possibly replaced or repaired.

Weitere Vorteile der Erfindung ergeben sich aus der Beschreibung und der Zeichnung. Ebenso können die vorstehend genannten und die noch weiter aufgeführten Merkmale je für sich oder zu mehreren in beliebigen Kombinationen Verwendung finden. Die gezeigten und beschriebenen Ausführungsformen sind nicht als abschließende Aufzählung zu verstehen, sondern haben vielmehr beispielhaften Charakter für die Schilderung der Erfindung.Further advantages of the invention will become apparent from the description and the drawings. Likewise, the features mentioned above and the features listed further can be used individually or in combination in any combination. The embodiments shown and described are not to be understood as exhaustive enumeration, but rather have exemplary character for the description of the invention.

Es zeigt:

Figur
eine schematische Darstellung einer EUV-Strahlungserzeugungsvorrichtung, welche eine Strahlführungs-Kammer und eine Vakuum-Kammer sowie eine Zwischen-Kammer mit einem überwachten Druckraum aufweist.
It shows:
figure
a schematic representation of an EUV radiation generating device having a beam guiding chamber and a vacuum chamber and an intermediate chamber with a monitored pressure chamber.

Die Figur zeigt eine EUV-Strahlungserzeugungsvorrichtung 1, welche eine Treiberlasereinrichtung 2, eine Strahlführungs-Kammer 3 sowie eine Vakuum-Kammer 4 aufweist. In der Vakuum-Kammer 4 ist eine Fokussiereinrichtung in Form einer Fokussierlinse 6 angeordnet, um einen CO2-Laserstrahl 5 an einer Zielposition Z zu fokussieren. Die in Fig. 1 gezeigte EUV-Strahlungserzeugungsvorrichtung 1 entspricht im Wesentlichen dem Aufbau, wie er in der US 2011/0140008 A1 beschrieben ist, die durch Bezugnahme zum Inhalt dieser Anmeldung gemacht wird. Auf die Darstellung von Messeinrichtungen zur Überwachung des Strahlengangs des Laserstrahls 5 wurde aus Gründen der Übersichtlichkeit verzichtet.The figure shows an EUV radiation generating device 1, which has a driver laser device 2, a beam guiding chamber 3 and a vacuum chamber 4. In the vacuum chamber 4, a focusing device in the form of a focusing lens 6 is arranged to focus a CO 2 laser beam 5 at a target position Z. The EUV radiation generating device 1 shown in FIG corresponds essentially to the structure, as in the US 2011/0140008 A1 which is incorporated by reference into the contents of this application. On the representation of measuring devices for monitoring the beam path of the laser beam 5 has been omitted for reasons of clarity.

Die Treiberlasereinrichtung 2 umfasst eine CO2-Strahlquelle sowie mehrere Verstärker zur Erzeugung eines Laserstrahls 5 mit hoher Strahlungsleistung (> 1 kW). Für eine detaillierte Beschreibung von möglichen Ausgestaltungen der Treiberlasereinrichtung 2 sei auf die US 2011/0140008 A1 verwiesen. Von der Treiberlasereinrichtung 2 wird der Laserstrahl 5 über einer Mehrzahl von Umlenkspiegeln 7 bis 11 der Strahlführungs-Kammer 3 sowie eines weiteren Umlenkspiegels 12 in der Vakuum-Kammer 4 auf die Fokussierlinse 6 umgelenkt, welche den Laserstrahl 5 an der Zielposition Z fokussiert, an der Zinn als Target-Material 13 angeordnet ist.The driver laser device 2 comprises a CO 2 beam source and a plurality of amplifiers for generating a laser beam 5 with high radiation power (> 1 kW). For a detailed description of possible embodiments of the driver laser device 2, reference may be made to FIGS US 2011/0140008 A1 directed. From the driver laser device 2, the laser beam 5 is deflected over a plurality of deflecting mirrors 7 to 11 of the beam guiding chamber 3 and a further deflecting mirror 12 in the vacuum chamber 4 to the focusing lens 6, which focuses the laser beam 5 at the target position Z, at the Tin is arranged as a target material 13.

Das Target-Material 13 wird von dem fokussierten Laserstrahl 5 getroffen und hierbei in einen Plasma-Zustand übergeführt, der zur Erzeugung von EUV-Strahlung 14 dient. Das Target-Material 13 wird der Zielposition Z mit Hilfe einer (nicht gezeigten) Bereitstellungseinrichtung zugeführt, welche das Target-Material entlang eines vorgegebenen Pfades führt, der die Zielposition 6 kreuzt. Für Details der Bereitstellung des Ziel-Materials sei ebenfalls auf die US 2011/0140008 A1 verwiesen.The target material 13 is struck by the focused laser beam 5 and thereby converted into a plasma state, which serves to generate EUV radiation 14. The target material 13 is supplied to the target position Z by means of a delivery device (not shown) which guides the target material along a predetermined path crossing the target position 6. For details of the provision of the target material is also on the US 2011/0140008 A1 directed.

In der Strahlführungs-Kammer 3 ist eine Einrichtung 15 zur Vergrößerung eines Strahldurchmessers des Laserstrahls 5 vorgesehen, welche einen ersten Off-Axis Parabolspiegel 16 mit einer ersten, konvex gekrümmten reflektierenden Oberfläche und einen zweiten Off-Axis Parabolspiegel 17 mit einer zweiten, konkav gekrümmten reflektierenden Oberfläche aufweist. Die reflektierenden Oberflächen eines Off-Axis Parabolspiegels 16, 17 bilden jeweils die Off-Axis Segmente eines (elliptischen) Paraboloids. Der Begriff "Off-Axis" bedeutet, dass die reflektierenden Oberflächen nicht die Rotationsachse des Paraboloids (und damit auch nicht den Scheitelpunkt des Paraboloids) enthalten.Provided in the beam guidance chamber 3 is a device 15 for increasing a beam diameter of the laser beam 5, which has a first off-axis parabolic mirror 16 with a first, convexly curved reflecting surface and a second off-axis parabolic mirror 17 with a second, concavely curved reflecting beam Surface has. The reflective surfaces of an off-axis parabolic mirror 16, 17 each form the off-axis segments of an (elliptical) paraboloid. The term "off-axis" means that the reflective surfaces do not include the axis of rotation of the paraboloid (and therefore not the apex of the paraboloid).

Wie in der Figur ebenfalls zu erkennen ist, ist zwischen der Strahlführungs-Kammer 3, genauer gesagt deren Gehäuse, und der Vakuum-Kammer 4 eine Zwischen-Kammer 18 angeordnet. An der Zwischen-Kammer 18, genauer gesagt an deren der Strahlführungs-Kammer 3 zugewandter Gehäusewand ist ein erstes die Zwischen-Kammer 18 gasdicht abschließendes Fenster 19 angebracht, welches zum Eintritt des Laserstrahls 5 von der Strahlführungs-Kammer 3 dient. Ein zweites Fenster 20 ist an der der Vakuum-Kammer 4 zugewandten Gehäusewand der Zwischen-Kammer 18 angebracht und dient zum Austritt des Laserstrahls 5 aus der Zwischen-Kammer 18 in die Vakuum-Kammer 4.As can also be seen in the figure, an intermediate chamber 18 is arranged between the beam guiding chamber 3, more precisely its housing, and the vacuum chamber 4. At the intermediate chamber 18, more precisely at the housing of the beam guiding chamber 3 facing a first intermediate chamber 18 gas-tight final window 19 is mounted, which serves for the entrance of the laser beam 5 of the beam guiding chamber 3. A second window 20 is attached to the vacuum chamber 4 facing housing wall of the intermediate chamber 18 and serves to exit the laser beam 5 from the intermediate chamber 18 in the vacuum chamber. 4

Eine Vakuum-Pumpe 21 dient der Erzeugung eines Betriebsdrucks p2 in der Vakuum-Kammer 4, der im Feinvakuum-Bereich (in der Regel bei deutlich weniger als 1,0 mbar) liegt. Der Betrieb der Vakuum-Kammer 4 unter Vakuum-Bedingungen ist erforderlich, da es in einer Restgas-Umgebung mit zu hohem Druck zu einer zu starken Absorption der erzeugten EUV-Strahlung 14 kommen würde. Demgegenüber wird die Strahlführungs-Kammer 3 bzw. der in dieser gebildete Innenraum mit einem deutlich höheren Druck p1 betrieben, der beispielsweise in der Größenordnung von ca. 5 mbar über Atmosphärendruck (1013 mbar) liegen kann. Die Strahlführungs-Kammer 3 wird somit gezielt gegenüber der Umgebung der EUV-Strahlerzeugungsvorrichtung 1 unter einen Überdruck gesetzt, um die optischen Elemente, die in der Strahlführungs-Kammer 3 angeordnet sind, vor Verschmutzungen zu schützen.A vacuum pump 21 is used to generate an operating pressure p 2 in the vacuum chamber 4, which is in the fine vacuum range (usually at significantly less than 1.0 mbar). The operation of the vacuum chamber 4 under vacuum conditions is required because it would come in a residual gas environment with too high pressure to excessive absorption of the generated EUV radiation 14. In contrast, the beam-guiding chamber 3 or the interior formed in this is operated at a significantly higher pressure p 1 , which may be, for example, in the order of about 5 mbar above atmospheric pressure (1013 mbar). The beam guiding chamber 3 is thus selectively pressurized with respect to the surroundings of the EUV jet generating device 1 in order to protect the optical elements arranged in the beam guiding chamber 3 from soiling.

In dem unwahrscheinlichen Fall, dass beide Fenster 19, 20 gleichzeitig zerstört werden, kann durch die Druckdifferenz zwischen der Strahlführungs-Kammer 3 und der Vakuum-Kammer 4 das Gas aus der Strahlführungs-Kammer 3 in den Innenraum der Vakuum-Kammer 4 gelangen und dort Reste bzw. Ablagerungen des Target-Materials 13 mitreißen sowie diese zu weiteren (nicht bildlich dargestellten) Baugruppen der EUV-Lithographieanlage transportieren. Bei diesen Baugruppen handelt es sich im Wesentlichen um ein Beleuchtungssystem zur Beleuchtung einer strukturtragenden Maske sowie um ein Abbildungssystem zur Abbildung der Struktur an der Maske auf ein lichtempfindliches Substrat (Wafer). Die weiteren Baugruppen bzw. die dort angeordneten optischen Elemente können durch das Target-Material kontaminiert werden, was ggf. zu einem Totalausfall der EUV-Lithographieanlage führen kann. Neben dem Gas aus der Strahlführungs-Kammer 3 kann auch Kühlwasser in den Innenraum der Vakuum-Kammer 4 gelangen und dort Reste bzw. Ablagerungen des Target-Materials 13 mitreißen sowie diese Reste zu weiteren (nicht bildlich dargestellten) Baugruppen der EUV-Lithographieanlage transportieren.In the unlikely event that both windows 19, 20 are destroyed at the same time, the pressure difference between the beam guiding chamber 3 and the vacuum chamber 4, the gas from the beam guiding chamber 3 in the interior of the vacuum chamber 4 arrive and there Entrain residues or deposits of the target material 13 and transport them to other (not shown) assemblies of the EUV lithography system. These assemblies are essentially an illumination system for illuminating a structure-bearing mask and an imaging system for imaging the structure on the mask onto a photosensitive substrate (wafer). The further assemblies or the optical elements arranged there can be contaminated by the target material, which may lead to a total failure of the EUV lithography system can lead. In addition to the gas from the beam-guiding chamber 3, cooling water can also enter the interior of the vacuum chamber 4 and carry along therewith residues or deposits of the target material 13 and transport these residues to further assemblies (not illustrated) of the EUV lithography system.

Durch die Verwendung einer primären Abdichtung in Form des zweiten Fensters 20 und einer sekundären Abdichtung in Form des ersten Fensters 19 kann die Gefahr einer solchen Kontamination deutlich reduziert werden, da ein gleichzeitiger Ausfall beider Fenster 19, 20 - wie oben erwähnt - extrem unwahrscheinlich ist. Wird nur das erste Fenster 19 zerstört, tritt zwar Gas bzw. Flüssigkeit von der Strahlführungs-Kammer 3 in die Zwischen-Kammer 18 ein, das zweite Fenster 20 verhindert aber den Eintritt dieses Gases bzw. der Flüssigkeit in die Vakuum-Kammer 4. Wird das zweite Fenster 20 z.B. aufgrund von thermischer Beanspruchung zerstört, tritt nur das in der Zwischen-Kammer 18 enthaltene Gas bzw. Flüssigkeit in die Vakuum-Kammer 4 über. Da das Volumen der Vakuum-Kammer 4 im Vergleich zum Volumen der Zwischen-Kammer 18 (anders als in der Figur dargestellt) deutlich größer ist, ist der Schaden, den die in die Vakuum-Kammer 4 eintretende Gas- bzw. Flüssigkeitsmenge anrichten kann, vergleichsweise gering.The use of a primary seal in the form of the second window 20 and a secondary seal in the form of the first window 19, the risk of such contamination can be significantly reduced, since a simultaneous failure of both windows 19, 20 - as mentioned above - is extremely unlikely. If only the first window 19 is destroyed, gas or liquid enters from the jet-guiding chamber 3 into the intermediate chamber 18, but the second window 20 prevents the entry of this gas or the liquid into the vacuum chamber 4 the second window 20 eg Destroyed due to thermal stress, only the gas or liquid contained in the intermediate chamber 18 enters the vacuum chamber 4 on. Since the volume of the vacuum chamber 4 is significantly larger than the volume of the intermediate chamber 18 (other than shown in the figure), the damage that the amount of gas or liquid entering the vacuum chamber 4 may cause is great. comparatively low.

Dennoch ist es günstig, eine Leckage in der Zwischen-Kammer 18, die beispielsweise auf die Zerstörung eines der Fenster 19, 20 zurückzuführen ist, möglichst frühzeitig zu erkennen, um im Fehlerfall geeignete Gegenmaßnahmen einleiten zu können, beispielsweise indem Öffnungen bzw. Ventile zwischen den Kammern unterschiedlicher Baugruppen der EUV-Lithographieanlage geschlossen werden und/oder die Vakuum-Kammer 4 bzw. die weiteren Baugruppen mit einem Inertgas geflutet werden, um dort einen Druck zu erzeugen, der den Druck des eintretenden Gases übersteigt und so dessen Eintreten verhindert.Nevertheless, it is favorable to be able to recognize a leak in the intermediate chamber 18, which is due, for example, to the destruction of one of the windows 19, 20, as early as possible in order to be able to initiate suitable countermeasures in the event of a fault, for example by opening or valves between them Chambers of different assemblies of the EUV lithography system are closed and / or the vacuum chamber 4 and the other modules are flooded with an inert gas to generate a pressure there that exceeds the pressure of the incoming gas and thus prevents it.

Zur Überwachung der Zwischen-Kammer 18 auf Leckage ist eine Zuführungseinrichtung 23 für ein Prüfgas 24 vorgesehen, welche ein Prüfgas-Reservoir 25 als Prüfgas-Bereitstellungseinrichtung aufweist, die das Prüfgas 24, beispielsweise Stickstoff oder Argon, enthält und dieses mit einem konstanten (ggf. geregelten) Speisedruck p0 bereitstellt. Das Prüfgas 24 wird über eine Zuführungsleitung 27 der Zwischen-Kammer 18 zugeführt. In der Zuführungsleitung ist eine Fest-Drossel 26 mit einer Drossel-Bohrung vorgesehen, welche den Prüfgas-Fluss in die Zwischen-Kammer 18 begrenzt.For monitoring the intermediate chamber 18 for leakage, a supply means 23 for a test gas 24 is provided, which has a test gas reservoir 25 as a test gas supply device containing the test gas 24, for example nitrogen or argon, and this with a constant (possibly. regulated) feed pressure p 0 provides. The test gas 24 is supplied via a supply line 27 of the intermediate chamber 18. In the supply line a fixed throttle 26 is provided with a throttle bore which limits the test gas flow into the intermediate chamber 18.

Ist die Zwischen-Kammer 18 leckagefrei, stimmt der Druck p in der Zwischen-Kammer 18 mit dem Speisedruck p0 überein und es strömt kein Prüfgas 24 durch die Zuführungsleitung 27 in die Zwischen-Kammer 18. Der von einem Druck-Sensor 28 zur Messung des Prüfgasdrucks p in der Zwischen-Kammer 18 gemessene Prüfgasdruck p stimmt somit mit dem Speisedruck p0 überein. Der Speisedruck p0 (und damit der Prüfgasdruck p im leckagefreien Fall) ist größer als der Druck in der Strahlführungs-Kammer 3 und größer als der Betriebsdruck p2 der Vakuum-Kammer 4 und kann beispielsweise ca. 1023 mbar betragen.If the intermediate chamber 18 is leak-free, the pressure p in the intermediate chamber 18 coincides with the feed pressure p 0 and no test gas 24 flows through the feed line 27 into the intermediate chamber 18. The pressure sensor 28 measures the pressure the Prüfgasdrucks p in the intermediate chamber 18 measured test gas pressure p is thus consistent with the feed pressure p 0 match. The feed pressure p 0 (and thus the Prüfgasdruck p in leak-free case) is greater than the pressure in the beam-guiding chamber 3 and greater than the operating pressure p 2 of the vacuum chamber 4 and may for example be about 1023 mbar.

Tritt eine ggf. geringfügige Leckage durch eine Undichtigkeit an einem oder beiden Fenstern 19, 20 auf, verringert sich der Prüfgasdruck p gegenüber dem Speisedruck p0. Dies kann von einer Leckage-Überwachungseinrichtung 29 ausgewertet werden, die zu diesem Zweck mit dem Druck-Sensor 28 in signaltechnischer Verbindung steht. Eine signaltechnische Verbindung mit der Zuführungseinrichtung 23 ist nicht erforderlich, sofern die Leckage-Erkennungseinrichtung 29 Zugriff auf eine Speichereinrichtung hat, in welcher der Zahlenwert für den fest vorgegebenen bzw. auf einen festen Wert geregelten Speisedruck p0 hinterlegt ist. Es versteht sich, dass die Leckage-Überwachungseinrichtung 29 in der Figur nur beispielhaft an der Zwischen-Kammer 18 angebracht ist und auch an anderer Stelle in der EUV-Strahlungserzeugungsvorrichtung 1 angeordnet sein kann.If a possibly slight leakage occurs due to a leak at one or both windows 19, 20, the test gas pressure p decreases compared to the feed pressure p 0 . This can be evaluated by a leakage monitoring device 29 which is in signal communication with the pressure sensor 28 for this purpose. A signaling connection to the supply device 23 is not required if the leakage detection device 29 has access to a memory device in which the numerical value for the fixed or fixed to a fixed value feed pressure p 0 is stored. It goes without saying that the leakage monitoring device 29 in the figure is only attached to the intermediate chamber 18 by way of example and can also be arranged elsewhere in the EUV radiation generating device 1.

Die Leckage-Überwachungseinrichtung 29 kann anhand eines plötzlichen, starken Druckabfalls in der Zwischen-Kammer 18 auf die Zerstörung eines der Fenster 19, 20 schließen, indem der gemessene Prüfgasdruck p in der Zwischen-Kammer 18 mit einem Fehler-Schwellwert für den Prüfgasdruck p verglichen wird. Fällt der Prüfgasdruck p unter den Fehler-Schwellwert, werden umgehend Gegenmaßnahmen eingeleitet, um die in der Vakuum-Kammer 4 bzw. in mit dieser verbundenen weiteren Vakuum-Kammern angeordneten optischen Elemente vor Kontaminationen zu schützen (s.o.).The leakage monitoring device 29 can conclude from the destruction of one of the windows 19, 20 by a sudden, strong pressure drop in the intermediate chamber 18, by comparing the measured Prüfgasdruck p in the intermediate chamber 18 with an error threshold value for Prüfgasdruck p becomes. If the test gas pressure p falls below the error threshold, countermeasures are promptly initiated in order to protect the optical elements arranged in the vacuum chamber 4 or in further vacuum chambers connected therewith from contamination (see above).

Die Leckage-Überwachungseinrichtung 29 reagiert bei geeignet gewähltem Durchmesser der Drosselbohrung (z.B. ca. 0,1 mm) sehr sensitiv auf kleine Leckagen der Zwischen-Kammer 18, wie sie beispielsweise bei einer unvollständigen Abdichtung der Fenster 19, 20 gegen das Gehäuse der Zwischen-Kammer 18, genauer gesagt gegen einen dort vorgesehenen Halter bzw. eine Fassung auftreten können. Die Detektion kleiner Leckage-Mengen kann einen Hinweis darauf liefern, dass undefinierte Zustände an den Bauteilen der Strahlführungs-Kammer 3 vorliegen. Durch den Vergleich des gemessenen Prüfgasdrucks p mit einem Warn-Schwellwert kann ggf. auf einen solchen Zustand reagiert werden, bevor es zum Fehlerfall bzw. zum Totalausfall eines der Fenster 19, 20 kommt. Beim Erreichen des Warn-Schwellwerts kann beispielsweise eine akustische oder optische Warnung an einen Bediener ausgegeben werden, damit dieser eine Wartung und Überprüfung der Fassung bzw. der Anlageflächen der Fenster 19, 20 vornehmen kann.The leakage monitoring device 29 reacts with a suitably selected diameter of the throttle bore (for example, about 0.1 mm) very sensitive to small leaks of the intermediate chamber 18, as for example in an incomplete sealing of the windows 19, 20 against the housing of the intermediate Chamber 18, more precisely against a holder provided there or a version may occur. The detection of small amounts of leakage can provide an indication that undefined states are present on the components of the beam-guiding chamber 3. By comparing the measured Prüfgasdrucks p with a warning threshold value can be reacted to such a condition, if necessary, before it comes to a fault or total failure of the window 19, 20. When the warning threshold value is reached, for example, an audible or visual warning can be output to an operator so that he can undertake maintenance and checking of the socket or contact surfaces of the windows 19, 20.

Eine solche frühe Warnung vor einer möglichen Zerstörung der Fenster 19, 20 ist insbesondere bei der Verwendung von Diamant als Fenster-Material von Vorteil, da ein durch den Abbrand bzw. die Zerstörung eines Diamant-Fensters 19, 20 erforderlicher Austausch mit erheblichen Kosten verbunden ist. Die Verwendung von Diamant als Fenster-Material ist aufgrund seiner hohen Wärmeleitfähigkeit vorteilhaft.Such an early warning of a possible destruction of the windows 19, 20 is particularly advantageous when using diamond as the window material, since a replacement required by the erosion or destruction of a diamond window 19, 20 is associated with considerable costs , The use of diamond as a window material is advantageous because of its high thermal conductivity.

Alternativ oder (wie in der Figur gezeigt) zusätzlich zur Messung des Prüfgasdrucks p in der Zwischen-Kammer 18 kann auch mit Hilfe eines Gasfluss-Sensors 30 eine Messung des Prüfgas-Flusses dv/dt des durch die Zuführungsleitung 27 strömenden Prüfgases 24 erfolgen. Der Prüfgas-Fluss dv/dt verschwindet ohne Leckage, da in diesem Fall der Speisedruck p0 und der Druck p in der Zwischen-Kammer 18 übereinstimmen. Der Prüfgas-Fluss steigt mit abfallendem Prüfgasdruck p in der Zwischen-Kammer 18 (entsprechend einer ansteigenden Druckdifferenz zwischen dem Speisedruck p0 und dem Prüfgasdruck p in der Zwischen-Kammer 18) an. Auch der Prüfgas-Fluss dv/dt kann von der Leckage-Überwachungseinrichtung 29 mit einem Fehler-Schwellwert bzw. mit einem Warnungs-Schwellwert verglichen werden, um einen Fehlerfall zu erkennen bzw. um eine Warnung auszugeben.Alternatively or (as shown in the figure) in addition to the measurement of the test gas pressure p in the intermediate chamber 18, a measurement of the test gas flow dv / dt of the test gas 24 flowing through the feed line 27 can also take place with the aid of a gas flow sensor 30. The test gas flow dv / dt disappears without leakage, since in this case the feed pressure p 0 and the pressure p in the intermediate chamber 18 coincide. The test gas flow increases with decreasing test gas pressure p in the intermediate chamber 18 (corresponding to an increasing pressure difference between the feed pressure p 0 and the Prüfgasdruck p in the intermediate chamber 18). The test gas flow dv / dt can also be compared by the leakage monitoring device 29 with an error threshold value or with a warning threshold value in order to detect an error case or to issue a warning.

Änderungen des Drucks p in der Zwischen-Kammer 18 können auch durch Temperaturänderungen des Prüfgases 24 hervorgerufen werden. Dies könnte ggf. zu einer Fehlermeldung führen, ohne dass tatsächlich eine Leckage in der Zwischen-Kammer 18 auftritt. Um derartige temperaturbedingte Druckänderungen auszugleichen, kann in die Zuführungsleitung 27 gezielt ein Leck bzw. eine (kleine) Öffnung eingebracht werden, über die das Prüfgas 24 für den Druckausgleich mit der Umgebung in Verbindung steht.Changes in the pressure p in the intermediate chamber 18 can also be caused by temperature changes of the test gas 24. This could possibly lead to an error message, without actually occurring a leakage in the intermediate chamber 18. In order to compensate for such temperature-induced pressure changes, a leak or a (small) opening can be introduced into the supply line 27 in a targeted manner, via which the test gas 24 communicates with the environment for pressure equalization.

Auf die oben beschriebene Weise kann die Betriebssicherheit und Zuverlässigkeit der EUV-Strahlungserzeugungsvorrichtung deutlich gesteigert werden. Es versteht sich, dass zur Leckage-Überwachung ggf. auf die Zuführung eines Prüfgases verzichtet werden kann, indem der Gasdruck in der Zwischen-Kammer direkt mittels eines Drucksensors überwacht wird.In the manner described above, the reliability and reliability of the EUV radiation generating device can be significantly increased. It is understood that for leakage monitoring, if necessary, the supply of a test gas can be dispensed with by monitoring the gas pressure in the intermediate chamber directly by means of a pressure sensor.

Claims (13)

  1. EUV radiation generating apparatus (1) comprising:
    a vacuum chamber (4) where a target material (13) can be positioned at a target position (Z) for generation of EUV radiation (14), and
    a beam guiding chamber (3) for guiding a laser beam (5) from a driver laser device (2) towards the target position (Z),
    an intermediate chamber (18) which is arranged between the vacuum chamber (4) and the beam guiding chamber (3),
    a first window (19) which seals the intermediate chamber (18) in a gas-tight manner for entry of the laser beam (5) from the beam guiding chamber (3) and
    a second window (20) which seals the intermediate chamber (18) in a gas-tight manner for exit of the laser beam (5) into the vacuum chamber (4),
    characterised by
    a feeding device (23) for supplying a test gas (24) to the intermediate chamber (18) and a leakage monitoring device (29) for monitoring a leak of the intermediate chamber (18) by means of the supplied test gas (24).
  2. EUV radiation generating apparatus according to claim 1, characterised in that the beam guiding chamber (3) has a higher pressure (p1) than the environment, in particular the environment outside the EUV radiation generating apparatus (1).
  3. EUV radiation generating apparatus according to claim 1 or 2, wherein the feeding device (23) is configured to generate a test gas pressure (p) in the intermediate chamber (4) which is greater than a pressure (p1) within the beam guiding chamber (3) and an operating pressure (p2) within the vacuum chamber (4).
  4. EUV radiation generating apparatus according to any one of the preceding claims, wherein the feeding device (23) has a provision device (25) for providing the test gas (24) at a feed pressure (p0) and a throttle (26) which is arranged between the pressure generating device (25) and the intermediate chamber (18).
  5. EUV radiation generating apparatus according to claim 4, wherein the feeding device (23) has a gas flow sensor (30) for determining a test gas flow (dv/dt) supplied to the intermediate chamber (18).
  6. EUV radiation generating apparatus according to any one of the preceding claims, further comprising: at least one pressure sensor (28) for determining a test gas pressure (p) in the intermediate chamber (18).
  7. EUV radiation generating apparatus according to any one of the preceding claims, further comprising: a vacuum generating device (21) for generating an operating pressure (p2) in the vacuum chamber (4).
  8. EUV radiation generating apparatus according to any one of the preceding claims, further comprising: a focusing device (6) for focusing the laser beam (5) at the target position (Z).
  9. EUV radiation generating apparatus according to claim 8, wherein the focusing device (6) is arranged within the vacuum chamber (4).
  10. EUV radiation generating apparatus according to any one of the preceding claims, wherein at least one of the windows (19, 20) is configured as a plane-parallel plate.
  11. EUV radiation generating apparatus according to any one of the preceding claims, wherein at least one of the windows (19, 20) is formed from diamond.
  12. EUV radiation generating apparatus according to any one of the preceding claims, wherein the beam guiding chamber (3) has a device (15) for expanding the laser beam (5).
  13. Method for operating an EUV radiation generating apparatus (1) according to any one of the preceding claims, comprising:
    generating EUV radiation (14) by guiding the laser beam (5) to the target material (13) positioned at the target position (Z),
    characterised by
    monitoring a leak of the intermediate chamber (18) by means of the test gas pressure (p) in the intermediate chamber (18) and/or by means of a test gas flow (dv/dt) of the test gas (24) supplied to the intermediate chamber (18).
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KR101679525B1 (en) 2016-11-24
CN104756607B (en) 2017-02-22
CN104756607A (en) 2015-07-01
DE102012217120A1 (en) 2014-03-27
US8847182B2 (en) 2014-09-30
JP2015530617A (en) 2015-10-15
EP2898756A1 (en) 2015-07-29
WO2014044392A1 (en) 2014-03-27
JP6042550B2 (en) 2016-12-14
KR20150060768A (en) 2015-06-03
US20140084186A1 (en) 2014-03-27

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