LITHOGRAPHING PLANT

Abstract

A lithography system (1) is disclosed, comprising a radiation source (3) for generating radiation (S) with a specific repetition frequency, and a mirror array with a plurality of mirrors (30), wherein each mirror (30) is configured to guide the radiation (S) in the lithography system (1) and has a mirror plate (31) that can be displaced by a tilting angle (W), wherein each mirror plate (31) is connected to a detection device (300) via an electrical conductor (80) for guiding the electric current (I) of the mirror plate (31) to the detection device (300), wherein the detection device (300) has a capacitor (311) coupled between the electrical conductor (80) and ground and is configured toto determine a steady-state voltage value (V3) of the voltage drop (V1) across the capacitor (311) as an indicative parameter value (P) for the intensity of the radiation (S) incident on the mirror plate (31) using the electric current (I) supplied to the measuring device (300).

Description

[0001] The present invention relates to a lithography system comprising a radiation source for generating radiation with a specific repetition frequency and a mirror array with a plurality of mirrors.

[0002] Microlithography is used to manufacture microstructured components, such as integrated circuits. The microlithography process is carried out using a lithography system, which includes an illumination system and a projection system. The image of a mask (reticule) illuminated by the illumination system is projected by the projection system onto a substrate, such as a silicon wafer, coated with a photosensitive layer (photoresist) and positioned in the image plane of the projection system. This transfers the mask structure onto the photosensitive coating of the substrate.

[0003] Driven by the pursuit of ever smaller structures in the fabrication of integrated circuits, EUV lithography systems are currently being developed that use light with a wavelength in the range of 0.1 nm to 30 nm, particularly 13.5 nm. Since most materials absorb light of this wavelength, such EUV lithography systems must use reflective optics, i.e., mirrors, instead of the refracting optics, i.e., lenses, used previously.

[0004] The use of so-called MEMS mirrors in the illumination system of a lithography system is well-established. "MEMS" stands for "Micro Electro Mechanical System." Such MEMS mirrors comprise a micromirror (also called a mirror plate) and an actuator. The actuator allows the micromirror's orientation to be changed. During operation of the lithography system, radiation (also called working light, especially EUV light) strikes the surface of the micromirror and is reflected. By changing the micromirror's orientation, the path the EUV light takes through the illumination system can be controlled. These MEMS mirrors are typically manufactured in an integrated design on a substrate. Advantageously, such systems require very little installation space.However, there are often significant space limitations for electronic components in an area behind the MEMS mirrors, i.e., on the side facing away from the working light.

[0005] The micromirrors can, for example, be mounted on a carrier plate and designed to be at least partially manipulable or tiltable, in order to allow movement of each micromirror in up to six degrees of freedom and thus highly precise positioning of the micromirrors relative to each other, especially in the millimeter range. This allows changes in optical properties that occur during operation of the lithography system, e.g., due to thermal influences, to be compensated for.

[0006] For the micromirror process, particularly in the six degrees of freedom, actuators are assigned to the mirrors and controlled via a feedback loop. A device for monitoring the tilt angle of each mirror is included as part of the feedback loop.

[0007] For example, WO 2009 / 100856 A1 discloses a faceted mirror for a projection exposure system of a lithography system, which has a large number of individually movable mirrors. To ensure the optical quality of a projection exposure system, very precise positioning of the movable mirrors is necessary. Furthermore, document DE 10 2013 209 442 A1 describes how the field faceted mirror can be designed as a microelectromechanical system (MEMS).

[0008] However, the photons from the EUV radiation source of the lithography system can, through the photoelectric effect, eject electrons from the mirror surfaces of the MEMS mirrors. This can lead to temporally and spatially varying current flows across the MEMS mirrors of the field facet mirror. These temporally and spatially varying current flows across the MEMS mirrors can significantly disrupt the monitoring of the tilt angle of the respective MEMS mirror.

[0009] DE 10 2023 203338 A1 proposes a lithography system comprising a radiation source for generating radiation with a specific repetition frequency, a mirror that can be tilted by a certain angle to guide the radiation within the lithography system, a detection device configured to detect the tilt angle of the mirror using a measurement signal with a frequency higher than the repetition frequency to provide a discrete-time tilt angle signal, and an evaluation unit. The evaluation unit is configured to discard certain signal values ​​of the provided tilt angle signal based on a signal indicating the times of impact of the radiation on the mirror surface to provide a refined discrete-time tilt angle signal, and to determine the position of the mirror using this refined discrete-time tilt angle signal.Because the measurement signal frequency is higher than the repetition frequency of the radiation source, the discrete-time tilt angle signal provided by the detection device has more signal values ​​than necessary to determine the mirror's position. This makes it possible to discard a subset of the discrete-time tilt angle signal's signal values. In this case, the evaluation unit discards those signal values ​​of the provided discrete-time tilt angle signal whose corresponding detection times correspond to the times when the radiation strikes the mirror's surface.

[0010] The evaluation unit of DE 10 2023 203 338 A1 is therefore suitable for providing a discrete-time tilt angle signal for specifying the tilt angle of the movable mirror with high accuracy. However, it would also be helpful for many applications to know the properties of the radiation incident on the mirror precisely.

[0011] Against this background, one object of the present invention is to create an improved lithography system.

[0012] According to a first aspect, a lithography system is proposed which includes a radiation source for generating radiation with a specific repetition frequency and a mirror array with a plurality of mirrors, wherein the respective mirror is set up to guide the radiation in the lithography system and has a mirror plate that can be displaced by a tilting angle.The respective mirror plate is connected to a detection device via an electrical conductor for guiding the electric current from the mirror plate to the detection device, the detection device having a capacitor coupled between the electrical conductor and ground and being configured to determine a steady-state voltage value of the voltage drop across the capacitor as an indicative parameter value for the intensity of the radiation directed onto the mirror plate using the electric current guided to the detection device.

[0013] By using the capacitor of the detection device, the electric current of the mirror plate can be integrated for each pulse and thus for each radiation pulse, especially EUV pulse.

[0014] The electric current from the mirror plate is either applied to a capacitor in the detection device or, alternatively (see the second and third aspects below), to an electrical resistor in the detection device. The indicative parameter can be a steady-state voltage value across the capacitor, a peak value across the electrical resistor, or a sampled voltage waveform across the electrical resistor.

[0015] In the first example, the electric charge transferred to the mirror plate can be derived from the determined steady-state voltage across the capacitor. Additionally, the time-integrated intensity of the radiation onto the mirror plate can be determined from the electric charge. In the second example, the electric current through the mirror plate can be derived from the determined peak value of the voltage across the resistor. Subsequently, the instantaneous intensity of the radiation onto the mirror plate can also be determined from the electric current. In the third example, the time course of the electric current through the mirror plate can be derived from the sampled time course of the voltage across the resistor.Subsequently, the temporal profile of the intensity of the radiation on the mirror plate can also be determined from the temporal profile of the electric current of the mirror plate.

[0016] This allows the following properties of the radiation on the mirror plate to be determined: - the time-integrated intensity of the radiation on the mirror plate; - the instantaneous value of the intensity of the radiation on the mirror plate; - the temporal progression of the intensity of the radiation on the mirror plate.

[0017] These determined properties of the radiation on the mirror plate are preferably fed to a processing unit. Based on one or more of these properties, the processing unit is configured to perform one or more of the following functions: - Suppression of disturbances in the detection device for detecting the tilt angle of the mirror; - Measures for pulse detection and trigger suppression in the sensor system; - Adjusting the spot center for the radiation onto the mirror plate; - Monitoring of the radiation source; - Determination of the intensity distribution in the far field of the radiation source; - Monitoring of pollution and transmission, especially correlating with a combination of the intensity of incident radiation with the intensity of absorbed radiation.

[0018] The lithography system or projection exposure system can be an EUV lithography system. EUV stands for "Extreme Ultraviolet" and refers to a wavelength of the working light between 0.1 nm and 30 nm. The lithography system or projection exposure system can also be a DUV lithography system. DUV stands for "Deep Ultraviolet" and refers to a wavelength of the working light between 30 nm and 250 nm. The guided radiation can be either EUV or DUV light.

[0019] The mirror array is in particular a micromirror array and the respective mirror is in particular a MEMS mirror.

[0020] According to one embodiment, the lithography system includes an evaluation unit which is configured to derive the electric charge that is replaced on the mirror plate from the determined steady-state voltage value of the voltage drop across the capacitor, and / or to determine the time-integrated intensity of the radiation on the mirror plate from the electric charge.

[0021] The steady-state voltage across the capacitor is indicative or representative of the electric charge replaced on the mirror plate, and thus of the intensity of the radiation incident on the mirror plate. In particular, the electric charge of the mirror plate is indicative of the time-integrated intensity of the radiation on the mirror plate.

[0022] According to another embodiment, the investigative device comprises an analog part and a digital part. The analog part includes: the capacitor coupled between the electrical conductor and ground, whose input node is connected to the electrical conductor and whose output node is connected to ground, an amplifier coupled to the input node, which is configured to provide an amplified voltage signal based on the voltage drop across the capacitor, and an analog-to-digital converter coupled to the amplifier, which is configured to convert the voltage signal provided by the amplifier into a digital voltage signal with N bits.

[0023] According to another embodiment, the digital part comprises: a gradient detection unit which is configured to detect a rising edge of the voltage drop across the capacitor based on the digital voltage signal provided by the analog-to-digital converter and, depending on this, to provide an initial trigger signal upon detection of a rising edge, a transient detection unit which is configured to provide a second trigger signal when a stable digital voltage signal within a certain tolerance range is present, and a storage unit which is configured to store the digital voltage signal provided by the analog-to-digital converter as the parameter value indicative of the intensity of the radiation directed onto the mirror plate, if the first trigger signal and the second trigger signal are provided.

[0024] According to another embodiment, the digital part of the detection device includes a filter unit connected between the output of the analog-to-digital converter and the storage unit. The filter unit is configured to filter the digital voltage signal provided by the analog-to-digital converter and, based on this, output a filtered digital voltage signal to the storage unit. The storage unit is configured to store the filtered digital voltage signal provided by the filter unit as the indicative parameter if the output signal of an AND gate that combines the first and second trigger signals has a positive signal state. The positive signal state is, for example, represented by a logic one, whereas a complementary negative signal state can be represented by a logic zero.

[0025] According to another embodiment, the analog part of the detection device has a controllable switch connected in parallel to the capacitor, by means of which the capacitor can be discharged using the output signal of the AND gate, particularly after storage by the memory unit. Thus, storage by the memory unit triggers the discharge of the capacitor. The discharged capacitor is then available for the next detection process. The AND gate can also be referred to as an AND circuit and represents a logical AND.

[0026] According to another embodiment, the analog section includes an overvoltage protection circuit connected between the input node and the amplifier. The overvoltage protection circuit is, for example, designed as a diode connected in parallel with the capacitor.

[0027] According to another embodiment, the storage unit is designed as a register array.

[0028] According to another embodiment, the gradient detection unit comprises an N-bit comparator and a register for providing a threshold value. The N-bit comparator is configured to set the first trigger signal to a positive signal state if the value of the digital voltage signal stored by the N-bit comparator is greater than the threshold value of the register.

[0029] According to another embodiment, the digital section comprises a series connection of latches between the output of the analog-to-digital converter and the register array. The latches are coupled to an N-bit comparator. In particular, the latches and the analog-to-digital converter are operated at the same clock frequency. The latches are each configured as state-controlled memory units, for example, as state-controlled flip-flops.

[0030] In this embodiment, the series connection of latches and the N-bit comparator coupled to them are part of the transient detection device.

[0031] According to a second aspect, a lithography system is proposed which comprises a radiation source for generating radiation with a specific repetition frequency and a mirror array with a plurality of mirrors, wherein each mirror is configured to guide the radiation within the lithography system and has a mirror plate that can be tilted. The respective mirror plate is connected to a detection device via an electrical conductor for conducting the electric current from the mirror plate to the detection device. The detection device has a resistor coupled between the electrical conductor and ground and is configured to determine a peak value of the voltage drop across the resistor as an indicative parameter value for the intensity of the radiation incident on the mirror plate, using the electric current supplied to the detection device.

[0032] The electric current of the mirror plate can be determined by peak detection of the voltage drop across the resistor of the measuring device. Subsequently, the instantaneous intensity of the radiation on the mirror plate can also be determined from the electric current of the mirror plate.

[0033] According to one embodiment, the lithography system has an evaluation unit which is designed to derive the electric current of the mirror plate from the determined peak value of the voltage drop across the resistor, and / or to determine the instantaneous value of the intensity of the radiation on the mirror plate from the electric current of the mirror plate.

[0034] The measured peak value of the voltage drop across the resistor is indicative or representative of the electric current through the mirror plate. The electric current through the mirror plate, in turn, is indicative or representative of the instantaneous intensity of the radiation on the mirror plate.

[0035] According to another embodiment, the investigative device comprises an analog part and a digital part. The analog part comprises: the resistor coupled between the electrical conductor and ground, whose input node is connected to the electrical conductor and whose output node is connected to ground, a peak detection circuit coupled to the input node, which is configured to provide a measurement voltage at its output node representing the peak value of the voltage drop across the resistor, a capacitor connected between the output node and ground to hold the measuring voltage, an amplifier coupled to the output node, which is configured to amplify the measurement voltage held by the capacitor and, depending on this, to provide an amplified measurement voltage on the output side, an analog-to-digital converter coupled to the amplifier, which is configured to convert the amplified measurement voltage provided by the amplifier into a digital voltage signal with N bits.

[0036] At the output node of the peak detection circuit, a high-value resistor is preferably connected in addition to the capacitor. The high-value resistor is configured to discharge the measurement voltage held by the capacitor, so that this voltage is supplied to the amplifier.

[0037] According to another embodiment, the digital part has a storage unit which is configured to store the digital voltage signal provided by the analog-to-digital converter as the parameter value indicative of the intensity of the radiation projected onto the mirror plate.

[0038] According to another embodiment, the storage unit of the digital part is designed as a register array.

[0039] According to another embodiment, the analog-to-digital converter and the register array are operated at the same clock frequency.

[0040] According to another embodiment, the analog part of the detection device comprises an overvoltage protection circuit connected between the input node and the peak detection circuit. The overvoltage protection circuit is, for example, designed as a diode connected in parallel with the resistor.

[0041] According to another embodiment, the amplifier comprises a voltage divider coupled between the output node and ground, with a first resistor and a second resistor.

[0042] According to another embodiment, the peak detection circuit comprises an operational amplifier and a diode connected downstream of the operational amplifier. The non-inverting input of the operational amplifier is connected to the input node, and the inverting input of the operational amplifier is connected to the center tap of the voltage divider.

[0043] According to a third aspect, a lithography system is proposed which includes a radiation source for generating radiation with a specific repetition frequency and a mirror array with a plurality of mirrors, wherein the respective mirror is set up to guide the radiation in the lithography system and has a mirror plate that can be displaced by a tilting angle.The respective mirror plate is connected to a detection device via an electrical conductor for guiding the electric current from the mirror plate to the detection device, the detection device having a resistor coupled between the electrical conductor and ground and being configured to determine a sampled time-dependent voltage profile of the voltage drop across the resistor as an indicative parameter value for the intensity of the radiation directed onto the mirror plate using the electric current supplied to the detection device.

[0044] The current through the mirror plate can be determined by sensing the voltage drop across the resistor of the measuring device and thus by recording the resulting time-dependent voltage profile. Subsequently, the time-dependent intensity of the radiation on the mirror plate can also be determined from the time-dependent electric current through the mirror plate.

[0045] According to one embodiment, the lithography system has an evaluation unit which is designed to derive a temporal profile of the electric current of the mirror plate from the sampled temporal voltage profile of the voltage drop across the resistor, and / or to determine a temporal profile of the intensity of the radiation on the mirror plate from the temporal profile of the electric current of the mirror plate.

[0046] The measured voltage profile across the resistor is indicative or representative of the electric current across the mirror plate over time. The electric current across the mirror plate over time, in turn, is indicative or representative of the intensity of the radiation on the mirror plate over time.

[0047] According to another embodiment, the investigative device comprises an analog part and a digital part. The analog part includes: the resistor coupled between the electrical conductor and ground, whose input node is connected to the electrical conductor and whose output node is connected to ground, an amplifier coupled to the input node and an analog-to-digital converter downstream of the amplifier, operated at a specific clock frequency, the amplifier is designed to amplify the voltage drop across the resistor and, depending on this, to provide an amplified voltage signal at the output, the analog-to-digital converter is designed to convert the amplified voltage signal provided by the amplifier into a digital voltage signal.

[0048] According to another embodiment, the digital part comprises: a gradient detection unit operated at a specific clock frequency, which is configured to detect a rising edge of the digital voltage signal provided by the analog-to-digital converter and, based on this, to provide an initial trigger signal upon detection of a rising edge, a logic circuit configured to provide a second trigger signal based on an AND operation of the first trigger signal and the specified clock frequency, and a storage unit coupled to the output of the analog-to-digital converter, which is configured to store the digital voltage signal provided by the analog-to-digital converter as a time- and value-discrete signal if the second trigger signal provided by the logic circuit has a positive signal state.

[0049] According to another embodiment, the specified clock frequency is greater than 100 MHz.

[0050] According to another embodiment, the memory unit is designed as a RAM memory.

[0051] According to another embodiment, the gradient detection unit comprises an N-bit comparator and a register for providing a threshold value. The N-bit comparator is configured to set the first trigger signal to a positive signal state if the value of the digital voltage signal stored by the N-bit comparator is greater than the threshold value of the register.

[0052] According to another embodiment, the logic circuit comprises an AND gate and an address counter. In particular, the AND gate is configured to output a control signal to the address counter by means of an AND operation on the first trigger signal and the specified clock frequency. The address counter is preferably configured to output the second trigger signal to the RAM memory based on the received control signal.

[0053] According to another embodiment, the mirror is a MEMS mirror. The MEMS mirror has a mirror plate that can be displaced about the tilt angle, a support plate for supporting the mirror plate, a base plate, a solid-state joint coupling the support plate and the base plate, and a capacitive sensor arranged between the support plate and the base plate.

[0054] According to another embodiment, a capacitive sensor is provided for measuring the tilt angle of the mirror plate of the MEMS mirror, wherein the electrodes of the capacitive sensor are comb-shaped and toothed.

[0055] According to another embodiment, the comb-shaped electrodes of the capacitive sensor each have a recess through which the solid-body joint coupling the carrier plate and the base plate is guided.

[0056] The solid-state joint is guided by the two recesses of the comb-shaped electrodes of the capacitive sensor, thus connecting the carrier plate and the base plate of the MEMS mirror. The mirror plate of the MEMS mirror can be tilted by the specified angle via this solid-state joint.

[0057] According to another embodiment, the lithography system has a vacuum housing in which, in particular, the radiation source, the mirror array, and the detection device are arranged. For example, the vacuum housing is designed such that a pressure of 1013.25 hPa to 10 -3 hPa, preferably 10 -3 up to 10 -8 hPa, preferably 10 -8 up to 10 -11 hPa prevails.

[0058] According to another embodiment, the lithography system has a control device arranged externally to the vacuum housing for controlling the radiation source by means of a control signal.

[0059] According to another embodiment, the radiation source is an EUV radiation source.

[0060] The respective unit, for example, the evaluation unit or the processing unit, can be implemented in hardware and / or software. In a hardware implementation, the unit can be a device or part of a device, for example, a computer, a microprocessor, or part of the control device. In a software implementation, the unit can be a computer program product, a function, a routine, part of program code, or an executable object.

[0061] The term "one" here is not necessarily to be understood as restricting the number to exactly one element. Rather, it can also refer to multiple elements, such as two, three, or more. Similarly, every other counter used here should not be interpreted as restricting the number to the exact number stated. Instead, numerical deviations, both higher and lower, are possible unless otherwise specified.

[0062] Other possible implementations of the invention also include combinations of features or embodiments described previously or subsequently with regard to the exemplary embodiments, even if not explicitly mentioned. In such cases, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention.

[0063] Further advantageous embodiments and aspects of the invention are the subject of the dependent claims and the exemplary embodiments of the invention described below. The invention will be explained in more detail below with reference to preferred embodiments and the accompanying figures. Fig. Figure 1 shows a schematic meridional section of a projection exposure system for EUV projection lithography; Fig. Figure 2 shows a schematic view of an embodiment of an aspect of the lithography system; Fig. Figure 3A shows a schematic view of a first embodiment of a detection device for determining a parameter value indicative of the intensity of the radiation emitted onto the mirror plate; Fig. Figure 3B shows an example of an extract of the course of the electric current supplied to the investigation device via the mirror plate; Fig. 3C shows an example of an excerpt of the course that results from the electric current after Fig. 3B resulting, at the capacitor of the investigation device according to Fig. 3A dropping voltage; Fig. 3D shows an example of an excerpt of the digital voltage signal waveform at the output of the analog-to-digital converter of the investigation device. Fig. 3A; Fig. Figure 3E shows a schematic view of a second embodiment of a detection device for determining a parameter value indicative of the intensity of the radiation emitted onto the mirror plate; Fig. Figure 4A shows a schematic view of a third embodiment of a detection device for determining a parameter value indicative of the intensity of the radiation emitted onto the mirror plate; Fig. Figure 4B shows an example of an extract of the course of the electric current supplied to the detection device via the mirror plate; Fig. 4C shows an example of an excerpt of the course that results from the electric current after Fig. 4B resulting from the resistance of the investigative institution according to Fig. 4A dropping voltage; Fig. Figure 4D shows an example of an excerpt of the digital voltage signal waveform at the output of the analog-to-digital converter of the investigation device. Fig. 4A; Fig. Figure 4E shows a schematic view of a fourth embodiment of a detection device for determining a parameter value indicative of the intensity of the radiation emitted onto the mirror plate; Fig. Figure 5A shows a schematic view of a fifth embodiment of a detection device for determining a parameter value indicative of the intensity of the radiation emitted onto the mirror plate; Fig. Figure 5B shows an example of an extract of the course of the electric current supplied to the investigation device of the mirror plate; Fig. Figure 5C shows an example of an excerpt of the digital voltage signal waveform at the output of the analog-to-digital converter of the investigation device. Fig. 5A; and Fig. Figure 5D shows a schematic view of a sixth embodiment of a detection device for determining a parameter value indicative of the intensity of the radiation directed onto the mirror plate.

[0064] In the figures, identical or functionally equivalent elements have been labelled with the same reference symbols, unless otherwise indicated. Furthermore, it should be noted that the representations in the figures are not necessarily to scale.

[0065] Fig. Figure 1 shows an embodiment of a projection exposure system 1 (lithography system), in particular an EUV lithography system. One embodiment of the illumination system 2 of the projection exposure system 1 has, in addition to a light or radiation source 3, an illumination optic 4 for illuminating an object field 5 in an object plane 6. In an alternative embodiment, the light source 3 can also be provided as a separate module from the rest of the illumination system 2. In this case, the illumination system 2 does not include the light source 3.

[0066] A reticule 7 arranged in the object field 5 is exposed. The reticule 7 is held by a reticule holder 8. The reticule holder 8 can be moved, particularly in a scanning direction, via a reticule displacement drive 9.

[0067] In the Fig. Figure 1 shows a Cartesian coordinate system with an x-direction x, a y-direction y, and a z-direction z. The x-direction x runs perpendicular to the plane of the drawing. The y-direction y runs horizontally, and the z-direction z runs vertically. The scan direction runs in the Fig. 1 along the y-direction y. The z-direction z runs perpendicular to the object plane 6.

[0068] The projection exposure system 1 comprises a projection optic 10. The projection optic 10 serves to image the object field 5 onto an image field 11 in an image plane 12. The image plane 12 is parallel to the object plane 6. Alternatively, an angle other than 0° between the object plane 6 and the image plane 12 is also possible.

[0069] A structure on the reticulum 7 is imaged onto a photosensitive layer of a wafer 13 located in the image plane 12 within the image field 11. The wafer 13 is held by a wafer holder 14. The wafer holder 14 can be moved, particularly along the y-direction y, via a wafer transfer drive 15. The movement of the reticulum 7 via the reticulum transfer drive 9 and of the wafer 13 via the wafer transfer drive 15 can be synchronized.

[0070] Light source 3 is an EUV radiation source. Light source 3 emits, in particular, EUV radiation 16, which is also referred to below as useful radiation, illumination radiation, or illumination light. The useful radiation 16 has a wavelength in the range between 5 nm and 30 nm. Light source 3 can be a plasma source, for example, an LPP source (Laser Produced Plasma) or a DPP source (Gas Discharged Produced Plasma). It can also be a synchrotron-based radiation source. Light source 3 can be a free-electron laser (FEL).

[0071] The illumination radiation 16 emanating from the light source 3 is focused by a collector 17. The collector 17 can be a collector with one or more ellipsoidal and / or hyperboloid reflective surfaces. The at least one reflective surface of the collector 17 can be illuminated by the illumination radiation 16 at grazing incidence (GI), i.e., with angles of incidence greater than 45°, or at normal incidence (NI), i.e., with angles of incidence less than 45°. The collector 17 can be structured and / or coated to optimize its reflectivity for the useful radiation and to suppress stray light.

[0072] After the collector 17, the illumination radiation 16 propagates through an intermediate focus in an intermediate focal plane 18. The intermediate focal plane 18 can represent a separation between a radiation source module, comprising the light source 3 and the collector 17, and the illumination optics 4.

[0073] The illumination optics 4 comprise a deflecting mirror 19 and, downstream in the beam path, a first faceted mirror 20. The deflecting mirror 19 can be a planar deflecting mirror or, alternatively, a mirror with an effect that influences the beam shape beyond the mere deflection effect. Alternatively or additionally, the deflecting mirror 19 can be designed as a spectral filter that separates a useful wavelength of the illumination radiation 16 from stray light of a different wavelength. If the first faceted mirror 20 is arranged in a plane of the illumination optics 4 that is optically conjugate to the object plane 6 as the field plane, it is also referred to as a field faceted mirror. The first faceted mirror 20 comprises a plurality of individual first facets 21, which can also be referred to as field facets. Of these first facets 21, the following are in the Fig. 1 only some examples are shown.

[0074] The first facets 21 can be designed as macroscopic facets, in particular as rectangular facets or as facets with an arcuate or semicircular border contour. The first facets 21 can be designed as planar facets or alternatively as convexly or concavely curved facets.

[0075] As is known, for example, from DE 10 2008 009 600 A1, the first facets 21 can themselves each be composed of a plurality of individual mirrors, in particular a plurality of micromirrors. The first facet mirror 20 can in particular be designed as a microelectromechanical system (MEMS system). For details, reference is made to DE 10 2008 009 600 A1.

[0076] Between the collector 17 and the deflecting mirror 19, the illumination radiation 16 runs horizontally, i.e. along the y-direction y.

[0077] In the beam path of the illumination optics 4, a second faceted mirror 22 is arranged downstream of the first faceted mirror 20. If the second faceted mirror 22 is arranged in a pupil plane of the illumination optics 4, it is also referred to as a pupil faceted mirror. The second faceted mirror 22 can also be arranged at a distance from a pupil plane of the illumination optics 4. In this case, the combination of the first faceted mirror 20 and the second faceted mirror 22 is also referred to as a specular reflector. Specular reflectors are known from US 2006 / 0132747 A1, EP 1 614 008 B1, and US 6 573 978 B1.

[0078] The second facet mirror 22 comprises a plurality of second facets 23. In the case of a pupil facet mirror, the second facets 23 are also referred to as pupil facets.

[0079] The second facets 23 can also be macroscopic facets, which may, for example, have round, rectangular, or hexagonal edges, or alternatively, facets composed of micromirrors. Reference is also made to DE 10 2008 009 600 A1 in this regard.

[0080] The second facets 23 can have planar or alternatively convex or concave curved reflective surfaces.

[0081] The illumination optics 4 thus form a double-faceted system. This basic principle is also known as a honeycomb condenser (English: Fly's Eye Integrator).

[0082] It can be advantageous not to arrange the second faceted mirror 22 exactly in a plane that is optically conjugate to a pupil plane of the projection optics 10. In particular, the second faceted mirror 22 can be arranged tilted relative to a pupil plane of the projection optics 10, as described, for example, in DE 10 2017 220 586 A1.

[0083] With the aid of the second faceted mirror 22, the individual first facets 21 are imaged into the object field 5. The second faceted mirror 22 is the last beam-shaping, or indeed the last, mirror for the illumination radiation 16 in the beam path before the object field 5.

[0084] In another embodiment of the illumination optics 4, not shown, a transmission optic can be arranged in the beam path between the second facet mirror 22 and the object field 5, which contributes in particular to imaging the first facets 21 into the object field 5. The transmission optic can have exactly one mirror, or alternatively two or more mirrors, arranged one behind the other in the beam path of the illumination optics 4. The transmission optic can, in particular, comprise one or two mirrors for normal incidence (NI mirrors) and / or one or two mirrors for grazing incidence (GI mirrors).

[0085] The lighting optics 4, in the version shown in the Fig. Figure 1 shows exactly three mirrors after the collector 17, namely the deflecting mirror 19, the first faceted mirror 20 and the second faceted mirror 22.

[0086] In a further embodiment of the lighting optics 4, the deflecting mirror 19 can also be omitted, so that the lighting optics 4 after the collector 17 can then have exactly two mirrors, namely the first faceted mirror 20 and the second faceted mirror 22.

[0087] The mapping of the first facets 21 by means of the second facets 23 or with the second facets 23 and a transmission optic into the object plane 6 is regularly only an approximate mapping.

[0088] The projection optics 10 comprise a plurality of mirrors Mi, which are numbered according to their arrangement in the beam path of the projection exposure system 1.

[0089] In the Fig. In the example shown, the projection optics 10 comprise six mirrors M1 to M6. Alternatives with four, eight, ten, twelve, or any other number of mirrors Mi are also possible. The projection optics 10 is a doubly obscured optic. The penultimate mirror M5 and the last mirror M6 each have an aperture for the illumination radiation 16. The projection optics 10 has an image-side numerical aperture that is greater than 0.5 and can also be greater than 0.6, for example, 0.7 or 0.75.

[0090] The reflective surfaces of the mirrors Mi can be designed as freeform surfaces without an axis of rotational symmetry. Alternatively, the reflective surfaces of the mirrors Mi can be designed as aspherical surfaces with exactly one axis of rotational symmetry of the reflective surface shape. The mirrors Mi, like the mirrors of the illumination optics 4, can have highly reflective coatings for the illumination radiation 16. These coatings can be designed as multilayer coatings, in particular with alternating layers of molybdenum and silicon.

[0091] The projection optics 10 has a large object-image offset in the y-direction y between a y-coordinate of a center of the object field 5 and a y-coordinate of the center of the image field 11. This object-image offset in the y-direction y can be approximately as large as a z-distance between the object plane 6 and the image plane 12.

[0092] The projection optics 10 can be anamorphic. In particular, they have different magnifications βx, βy in the x and y directions. The two magnifications βx, βy of the projection optics 10 are preferably (βx, βy) = (+ / - 0.25, ± 0.125). A positive magnification β indicates a projection without image inversion. A negative magnification β indicates a projection with image inversion.

[0093] The projection optics 10 thus lead to a reduction in the x-direction x, that is, in the direction perpendicular to the scan direction, in a ratio of 4:1.

[0094] The projection optics 10 lead to a reduction of 8:1 in the y-direction y, that is, in the scan direction.

[0095] Other magnification ratios are also possible. Magnification ratios with the same sign and absolute value in the x and y directions (x, y), for example with absolute values ​​of 0.125 or 0.25, are also possible.

[0096] The number of intermediate image planes in the x and y directions x, y in the beam path between the object field 5 and the image field 11 can be the same or, depending on the design of the projection optics 10, different. Examples of projection optics with different numbers of such intermediate images in the x and y directions x, y are known from US 2018 / 0074303 A1.

[0097] Each of the second facets 23 is assigned to exactly one of the first facets 21 to form an illumination channel for illuminating the object field 5. This can result, in particular, in illumination according to Köhler's principle. The far field is divided into a multitude of object fields 5 with the help of the first facets 21. The first facets 21 generate a plurality of images of the intermediate focus on the second facets 23 assigned to each of them.

[0098] The first facets 21 are each superimposed on a corresponding second facet 23 to illuminate the object field 5 on the reticle 7. The illumination of the object field 5 is particularly homogeneous. It preferably exhibits a uniformity error of less than 2%. Field uniformity can be achieved by superimposing different illumination channels.

[0099] The illumination of the entrance pupil of the projection optics 10 can be geometrically defined by arranging the second facets 23. By selecting the illumination channels, in particular the subset of the second facets 23 that carry light, the intensity distribution in the entrance pupil of the projection optics 10 can be adjusted. This intensity distribution is also referred to as the illumination setting or illumination pupil filling.

[0100] Another preferred pupil uniformity in the area of ​​defined illuminated sections of an illumination pupil of the illumination optics 4 can be achieved by a redistribution of the illumination channels.

[0101] Further aspects and details of the illumination of the object field 5 and, in particular, the entrance pupil of the projection optics 10 are described below.

[0102] The projection optics 10 can, in particular, have a homocentric entrance pupil. This can be accessible. It can also be inaccessible.

[0103] The entrance pupil of the projection optics 10 cannot always be illuminated exactly by the second faceted mirror 22. When the projection optics 10 image the center of the second faceted mirror 22 telecentrically onto the wafer 13, the aperture rays often do not intersect at a single point. However, a surface can be found where the pairwise determined separation of the aperture rays is minimized. This surface represents the entrance pupil or a surface conjugate to it in real space. In particular, this surface exhibits a finite curvature.

[0104] The projection optics 10 may have different entrance pupil positions for the tangential and sagittal beam paths. In this case, an imaging element, in particular an optical component of the transmission optics, should be provided between the second faceted mirror 22 and the reticle 7. This optical element can accommodate the different positions of the tangential and sagittal entrance pupils.

[0105] During the Fig. In the arrangement of the components of the illumination optics 4 shown in Figure 1, the second faceted mirror 22 is arranged in a plane conjugate to the entrance pupil of the projection optics 10. The first faceted mirror 20 is arranged tilted relative to the object plane 6. The first faceted mirror 20 is arranged tilted relative to an arrangement plane defined by the deflecting mirror 19. The first faceted mirror 20 is arranged tilted relative to an arrangement plane defined by the second faceted mirror 22.

[0106] Fig. Figure 2 shows a schematic view of an embodiment of an aspect of a lithography system or projection exposure system 1, as used, for example, in Fig. 1 is shown.

[0107] This shows Fig. 2 the from radiation source 3 of the lithography system 1 to Fig. 1. Generated radiation S, which has a specific repetition frequency. Furthermore, the Fig. 2. A mirror 30, which can be displaced by a tilting angle W, for guiding the radiation S in the lithography system 1. The mirror 30 can be designed as a MEMS mirror, for example, to be part of one of the mirrors 20, 22, M1 - M6 of the lithography system 1. Fig. to be 1. The mirror 30 is in particular one mirror of a plurality of mirrors of a mirror array, in particular a MEMS mirror array.

[0108] The MEMS mirror 30 has a mirror plate 31 that can be displaced about the tilt angle W, a support plate 32 for supporting the mirror plate 31, a base plate 33, a solid-state joint 34 coupling the support plate 32 and the base plate 33, and a capacitive sensor 35 of a detection device 40 arranged between the support plate 32 and the base plate 33. The detection device 40 is configured to detect the tilt angle W of the MEMS mirror 30 by means of a measurement signal MS with a measurement signal frequency to provide a discrete-time tilt angle signal K. The measurement signal frequency is higher than the repetition frequency. For example, the measurement signal frequency is at least twice as high as the repetition frequency.

[0109] The MEMS mirror 30 is displaceable in particular in two tilting axes, preferably in two mutually orthogonal tilting axes. The sectional view of the MEMS mirror 30 of the Fig. Figure 2 shows a tilting axis. The detection device 40 of the Fig. Assembly 2 comprises the aforementioned capacitive sensor 35 and two sensor units 41 and 42 per tilting axis. The capacitive sensor 35 is configured to measure the tilt angle W of the mirror plate 31 of the MEMS mirror 30. The electrodes 36, 37 of the capacitive sensor 35 are comb-shaped and interlocked. The capacitive sensor 35 has an upper electrode 36, which is coupled to the carrier plate 32. Furthermore, the capacitive sensor 35 has a lower electrode 37, which is coupled to the base plate 33. The respective sensor units 41, 42 are configured to excite the capacitive sensor 35 by means of an excitation signal AS and, in response, to receive the measurement signal MS.

[0110] Two control units 51, 52 are provided per tilting axis for actuating the MEMS mirror 30. The upper electrode 36 of the capacitive sensor 35 is coupled to ground via resistor 61. Furthermore, the mirror plate 31 is coupled to ground via resistor 62. Additionally, the mirror plate 31 is connected to a detection device 70 via an electrical conductor 80 to conduct the electric current I from the mirror plate 31 to the detection device 70. In the example of the Fig. 2 the electrical conductor 80 is connected to the mirror plate 31 via the resistor 62.

[0111] The measuring device 70 is designed to determine an indicative parameter value P for the intensity of the radiation S directed onto the mirror plate 31 using the electric current I supplied to the measuring device 70.

[0112] For example, the detection device 70 can have a capacitor coupled between the electrical conductor 80 and ground (see Fig. 3A, Fig. 3E). In this case, the indicative parameter value P can be formed as a steady-state voltage value of the voltage across the capacitor.

[0113] In alternative embodiments, the detection device 70 has a resistor coupled between the electrical conductor 80 and ground (see Fig. 4A, Fig. 4E, Fig. 5A and Fig. 5D). In these examples, the indicative parameter value P can be a determined peak value of the voltage drop across the resistor. Alternatively, the indicative parameter value P can be a sampled time-dependent voltage waveform of the voltage drop across the resistor. The first example, where the indicative parameter value P is the steady-state voltage value across the capacitor, is described below with reference to the Fig. 3A to 3E are discussed. The second example, in which the indicative parameter value P is defined as the determined peak value of the voltage drop across the resistance of the measuring device, is discussed with reference to the Fig. 4A to 4E are discussed. The third example, in which the indicative parameter value P is defined as the sampled time-dependent voltage profile of the voltage drop across the resistor of the detection device, is discussed with reference to the Fig. 5A to 5D explained.

[0114] For each of these examples, the determination unit 70 transmits the determined indicative parameter value P to an evaluation unit 90 (see Fig. 2) can be output. Details on this will be provided below with reference to the Fig. 3A to 5D explained in more detail.

[0115] This shows the Fig. Figure 3A shows a schematic view of a first embodiment of a detection device 300 for determining an indicative parameter value P for the intensity of the radiation S incident on the mirror plate 31. The detection device 300 of Fig. 3A is an exemplary embodiment of the investigation device 70 of the Fig. 2.

[0116] Investigation Unit 300 of the Fig. 3A is connected to the detection device 300 via the electrical conductor 80 for conducting the electric current I of the mirror plate 31. This is shown in the Fig. 3B is an example of an extract of the course of the electric current I supplied to the investigation device 300 of the mirror plate 31. As the Fig. Figure 3B shows that the electric current I of the mirror plate 31 is formed as a current pulse, which results from the radiation S incident on the mirror plate 31.

[0117] Investigation Unit 300 of the Fig. 3A has a capacitor 311 coupled between the electrical conductor 80 and ground and is designed to determine a steady-state voltage value V3 of the voltage V1 dropping across the capacitor 311 as the indicative parameter value P for the intensity of the radiation S directed onto the mirror plate 31 using the electric current I supplied to the measuring device 300.

[0118] For this purpose, the investigation unit 300 of the Fig. Figure 3A comprises an analog section 310 and a digital section 320. The analog section 310 includes the capacitor 311, which is coupled between the electrical conductor 80 and ground. Its input node K1 is connected to the electrical conductor 80, and its output node K2 is connected to ground. Figure 311 shows the following: Fig. 3C an example of an excerpt of the course of the electric current I according to Fig. 3B resulting, at the capacitor 311 of the investigation device 300 after Fig. 3A dropping voltage V1.

[0119] Furthermore, the analog part 310 includes an amplifier 312 coupled to the input node K1, which is configured to provide an amplified voltage signal V2 based on the voltage V1 across the capacitor 311.

[0120] As the Fig. As shown in Figure 3A, an overvoltage protection circuit 314 can be connected between the input node K1 and the amplifier 312.

[0121] Furthermore, the analog section 310 includes an analog-to-digital converter 313 coupled to the amplifier 312. The analog-to-digital converter 313 is configured to convert the voltage signal V2 provided by the amplifier 312 into a digital voltage signal V3 (see Fig. to convert 3D) with N bits. This is illustrated by the Fig. 3D example of an excerpt of the course of the digital voltage signal V3 at the output of the analog-to-digital converter 313 of the detection device 300 according to Fig. 3A.

[0122] As the Fig. Figure 3A further illustrates that the digital part 320 of the detection device 300 comprises a gradient detection unit 321, a transient detection unit 322 and a storage unit 323.

[0123] The gradient detection unit 321 can also be referred to as a gradient detection circuit or rising signal detection. The gradient detection unit 321 is configured to detect a rising edge of the voltage V1 across the capacitor 311, based on the digital voltage signal V3 provided by the analog-to-digital converter 313, and, depending on this, to provide a first trigger signal T1 upon detection of a rising edge. In this example, the first trigger signal T1 is a digital signal with the possible signal states 1 and 0. Signal state 1 can also be referred to as a positive signal state, whereas signal state 0 can also be referred to as a negative signal state.

[0124] The settling detection unit 322 can also be referred to as a settling detection circuit or settling detection. The settling detection unit 322 is designed to provide a second trigger signal T2 when a digital voltage signal V3 is stable within a specific tolerance range. "Stable within a specific tolerance range" for the digital voltage signal V3 means that the settling process is complete.

[0125] The storage unit 323 can also be referred to as memory or storage. The storage unit 323 is configured to store the digital voltage signal V3 provided by the analog-to-digital converter 313 as the parameter value P indicative of the radiation intensity S projected onto the mirror plate 31, provided that the first trigger signal T1 and the second trigger signal T2 are provided, in other words, set or have a respective positive signal state.

[0126] As the Fig. As further illustrated in Figure 3A, a filter unit 324 can be connected between the output of the analog-to-digital converter 313 and the memory unit 323. The filter unit 324 can also be referred to as a filter. The filter unit 324 is configured to filter the digital voltage signal V3 provided by the analog-to-digital converter 313 and, based on this, output a filtered digital voltage signal V3 to the memory unit 323. The memory unit 323 is then configured to store the filtered digital voltage signal V3 provided by the filter unit 324 as the indicative parameter P if an output signal T3 of an AND gate 325, which links the first trigger signal T1 and the second trigger signal T2, has a positive signal state.

[0127] As the Fig. Figure 3A further shows that the analog section 310 can have a controllable switch 315 connected in parallel to the capacitor 311. By means of the switch 315, the capacitor 311 can be discharged, in particular using the output signal T3 of the AND gate 325, preferably after storage by the memory unit 323, so that the capacitor 311 is discharged for a new acquisition process.

[0128] Fig. Figure 3E shows a schematic view of a second embodiment of a detection device 300 for determining an indicative parameter value P for the intensity of the radiation S incident on the mirror plate 31. The second embodiment according to Fig. 3E is based on the first embodiment according to Fig. 3A. In the second embodiment according to Fig. 3E is the overvoltage protection circuit 314 designed as a diode connected in parallel to the capacitor 311.

[0129] The memory unit 323 of the Fig. 3E is configured as a register array. The gradient detection unit 321 of the Fig. 3E comprises an N-bit comparator 326 and a register 327 for providing a threshold value. The N-bit comparator 326 is configured to set the first trigger signal T1 to a positive signal state if the value of the digital voltage signal V3 stored by the N-bit comparator 326 is greater than the threshold value of the register 327.

[0130] As the Fig. 3E further shows that the digital part 320 of the Fig. 3E is a series connection of latches 328 connected between the output of the analog-to-digital converter 313 and the register array 323. The latches 328 are coupled to an N-bit comparator 329. The latches 328 and the analog-to-digital converter 313 are preferably operated at the same clock frequency. In this embodiment according to Fig. 3E are the series connection of latches 328 and the N-bit comparator 329 coupled to them, which form part of the transient detection device 322.

[0131] In short, the examples of Fig. 3A - 3E The current I on the mirror plate 31 is integrated via the capacitor 311. The radiation S, which is shaped as an EUV pulse, causes a significant increase in the capacitor voltage V1. After the EUV pulse, the capacitor voltage V1 remains essentially constant (negligible for potential leakage currents). After detection of a rising edge of the capacitor voltage V1 and later after the transient response, the output of the analog-to-digital converter 313 is stored in the memory unit 323. A sampling rate of approximately 1 MHz is sufficient in this case.

[0132] In summary, the examples of Fig. 3A - 3E the indicative parameter P is formed as a steady-state voltage value V3 of the voltage V1 dropping across the capacitor 311.

[0133] The evaluation unit 90 after Fig. 2 is used for the examples of Fig. 3A - 3E are set up to derive the electric charge which is replaced on the mirror plate 31 from the determined steady-state voltage value V3 of the voltage V1 dropping across the capacitor 311 and / or to determine the time-integrated intensity of the radiation S on the mirror plate 31 from the electric charge.

[0134] Furthermore, the Fig. Figure 4A shows a schematic view of a third embodiment of a detection device 400 for determining an indicative parameter value P for the intensity of the radiation S incident on the mirror plate 31. The detection device 400 of Fig. 4A is an exemplary embodiment of the investigation device 70 according to Fig. 2.

[0135] Investigation Unit 400 of the Fig. 4A is connected via the electrical conductor 80 to the detection device 400 for conducting the electric current I of the mirror plate 31. The following is shown. Fig. 4B is an example of an extract of the course of the electric current I of the mirror plate 31 at the investigation device 400. In particular, the Fig. 4B of the Fig. 3B. How the Fig. Figure 4B shows that the electric current I of the mirror plate 31 is formed as a current pulse, which results from the radiation S incident on the mirror plate 31.

[0136] Investigation Unit 400 of the Fig. 4A has an electrical resistance 411 coupled between the electrical conductor 80 and ground and is designed to determine a peak value V5 of the voltage V4 dropping across the resistance 411 as the indicative parameter value P for the intensity of the radiation S directed onto the mirror plate 31 using the current I supplied to the measuring device 400.

[0137] For this purpose, the investigation unit 400 of the Fig. Figure 4A comprises an analog section 410 and a digital section 420. The analog section 410 includes the electrical resistor 411, which is coupled between the electrical conductor 80 and ground. Its input node K3 is connected to the electrical conductor 80, and its output node K4 is connected to ground. Furthermore, the analog section 410 includes a peak-value detection circuit 412, coupled to the input node K3. This circuit is configured to provide a measurement voltage V6 at its output node K5, representing the peak value V5 of the voltage V4 across the resistor 411. Figure 4A illustrates this circuit. Fig. 4C an example of an excerpt of the course of the electric current I according to Fig. 4B resulting, at a resistance 417 of the investigation facility 400 after Fig. 3A dropping voltage V6.

[0138] The analog section 410 also has a capacitor 413 connected between the output node K5 and ground to maintain the measuring voltage V6. At the output node K5, according to... Fig. An amplifier 414 is coupled to terminal 4A. The amplifier 414 is configured to amplify the measurement voltage V6 held by the capacitor 413 and, depending on this, to provide an amplified measurement voltage V7 at its output. An analog-to-digital converter 415 is coupled to the output of the amplifier 414. The analog-to-digital converter 415 is configured to convert the amplified measurement voltage V7 provided by the amplifier 414 into a digital voltage signal V8 with N bits. The following is shown in Figure 4A. Fig. 4D shows an example of an excerpt of the course of the digital voltage signal V8 at the output of the analog-to-digital converter 415 of the detection device 400.

[0139] At the output node K5 of the peak detection circuit 412, the high-impedance resistor 417 is preferably coupled in addition to the capacitor 413. The high-impedance resistor 417 is configured to discharge the measurement voltage V6 held by the capacitor 413, so that this voltage can be supplied to the amplifier 414. The peak detection circuit 412 rapidly follows a rising voltage V4 across the resistor 411. The decay time of the capacitor voltage V6 is defined by the resistor 417. In this case, a sampling rate of approximately 200 kHz is sufficient for a repetition frequency of up to 100 kHz.

[0140] Furthermore, the analogous part 410 of the investigation facility 400 has according to Fig. 4A preferably an overvoltage protection circuit 416 connected between the input node K3 and the peak value detection circuit 412.

[0141] The digital part 420 of the investigation facility 400 according to Fig. 4A includes a storage unit 421. The storage unit 421 can also be referred to as memory or storage. The storage unit 421 is configured to store the digital voltage signal V8 provided by the analog-to-digital converter 415 as the parameter value P indicative of the radiation intensity S directed onto the mirror plate 31.

[0142] Fig. Figure 4E shows a schematic view of a fourth embodiment of a detection device 400 for determining an indicative parameter value P for the intensity of the radiation S incident on the mirror plate 31. The fourth embodiment according to Fig. 4E is based on the third embodiment according to Fig. 4A. In the fourth embodiment according to Fig. In module 4E, the memory unit 421 is configured as a register array. The analog-to-digital converter 415 and the register array 421 are operated at the same clock frequency f4.

[0143] The amplifier 414 of the Fig. 4E comprises a voltage divider R1, R2 coupled between the output node K5 and ground, with a first resistor R1 and a second resistor R2. The peak value detection circuit 412 of the Fig. 4E comprises an operational amplifier 418 and a diode 419 connected downstream of the operational amplifier 418. The non-inverting input of the operational amplifier 418 is connected to the input node K3 of the detection device 400. The inverting input of the operational amplifier 418 is connected to the center tap of the voltage divider R1, R2.

[0144] In summary, the examples of Fig. 4A - 4E the indicative parameter P is formed as a peak value V5 of the voltage V4 falling across the resistor 411.

[0145] The evaluation unit 90 after Fig. 2 is used for the examples of Fig. 4A - 4E are set up to derive the electric current I of the mirror plate 31 from the determined peak value V5 of the voltage V4 dropping across the resistor 411 and / or to determine the instantaneous value of the intensity of the radiation S on the mirror plate 31 from the electric current I of the mirror plate 31.

[0146] Furthermore, it shows Fig. Figure 5A shows a schematic view of a fifth embodiment of a detection device 500 for determining an indicative parameter value P for the intensity of the radiation S incident on the mirror plate 31. The detection device 500 according to Fig. 5A is an exemplary embodiment of the investigation device 70 according to Fig. 2.

[0147] Investigation Unit 500 of the Fig. 5A is connected to the detection device 500 via the electrical conductor 80 to carry the electric current I of the mirror plate 31. The following is shown. Fig. 5B is an example of an extract of the course of the electric current I supplied to the investigation device 500 of the mirror plate 31. Here, the Fig. 5B of the Fig. 3B and the Fig. 4B. How the Fig. Figure 5B shows that the electric current I of the mirror plate 31 is formed as a current pulse, which results from the radiation S incident on the mirror plate 31.

[0148] Investigation Unit 500 of the Fig. 5A has a resistor 511 coupled between the electrical conductor 80 and ground and is designed to determine a sampled time-dependent voltage profile V12 of the voltage V9 dropping across the resistor 511 as an indicative parameter value P for the intensity of the radiation S directed onto the mirror plate 31 using the electric current I supplied to the detection device 500.

[0149] For this purpose, the investigation unit 500 points out the Fig. Figure 5A comprises an analog section 510 and a digital section 520. The analog section 510 includes a resistor 511 coupled between the electrical conductor 80 and ground, whose input node K6 is connected to the electrical conductor 80 and whose output node K7 is connected to ground. Furthermore, the analog section 510 includes an amplifier 512 coupled to the input node K6 and an analog-to-digital converter 513 connected downstream of the amplifier 512 and operating at a specific clock frequency f5. The amplifier 512 is configured to amplify the voltage V9 across the resistor 511 and, depending on this, provide an amplified voltage signal V10 at its output. The analog-to-digital converter 513 is further configured to convert the amplified voltage signal V10 provided by the amplifier 512 into a digital voltage signal V11 with N bits. The Fig. 5C an example of an excerpt of the course of the digital voltage signal V11 at the output of the analog-to-digital converter 513 of the detection device 500 according to Fig. 5A.

[0150] The digital part 520 of the investigation facility 500 according to Fig. 5A includes a gradient detection unit 521 operated at the specified clock frequency f5. The gradient detection unit 521 is configured to detect a rising edge of the digital voltage signal V11 provided by the analog-to-digital converter 513 and, based on this, to provide a first trigger signal S1 upon detection of a rising edge.

[0151] Furthermore, the digital part comprises 520 according to Fig. 5A a logic circuit 522. The logic circuit 522 is configured to provide a second trigger signal S2 based on an AND operation of the first trigger signal S1 and the specified clock frequency f5. Furthermore, the digital section 520 includes a memory unit 523 coupled to the output of the analog-to-digital converter 513. The memory unit 523 can also be referred to as memory or storage. The memory unit 523 is configured to store the digital voltage signal V11 provided by the analog-to-digital converter 513 as a time- and value-discrete signal V12 if the second trigger signal S2 provided by the logic circuit 522 has a positive signal state. Preferably, the specified clock frequency f5 is greater than 100 MHz. In this case, an analog-to-digital converter 513 with a high speed, particularly with a frequency greater than 100 MHz, is advantageous.Furthermore, high-speed RAM is advantageous.

[0152] Fig. Figure 5D shows a schematic view of a sixth embodiment of a detection device 500 for determining an indicative parameter value P for the intensity of the radiation S incident on the mirror plate 31. The sixth embodiment according to Fig. 5D is based on the fifth embodiment according to Fig. 5A.

[0153] In the sixth embodiment according to Fig. In 5D, the memory unit 523 is configured as RAM. The gradient detection unit 521 according to Fig. 5D comprises an N-bit comparator 524 and a register 525 for providing a threshold value. The N-bit comparator 524 is configured to set the first trigger signal S1 to a positive signal state if the value of the digital voltage signal V11 stored by the N-bit comparator 524 is greater than the threshold value of the register 525.

[0154] The logic circuit 522 according to Fig. The 5D comprises an AND gate 526 and an address counter 527. The AND gate 526 is configured to output a control signal S3 to the address counter 527 by means of an AND operation on the first trigger signal S1 and the specified clock frequency f5. The address counter 527 is configured to output the second trigger signal S2 to the RAM 523 based on the received control signal S3.

[0155] In summary, the examples of Fig. 5A - 5D the indicative parameter P is formed as the sampled time voltage profile V12 of the voltage V9 dropping across the resistor 511.

[0156] The evaluation unit 90 after Fig. 2 is used for the examples of Fig. 5A - 5D are set up to derive a time course of the electric current I of the mirror plate 31 from the sampled time course of the voltage V12 of the voltage V9 dropping across the resistor 511, and / or to determine a time course of the intensity of the radiation S on the mirror plate 31 from the time course of the electric current I of the mirror plate 31.

[0157] Although the present invention has been described using exemplary embodiments, it can be modified in many ways. REFERENCE MARK LIST 1 Projection exposure system 2 Lighting system 3. Radiation source 4 Lighting optics 5 object field 6 Object level 7 reticles 8 label holders 9 Reticle displacement drive 10 Projection optics 11 Image field 12 Image plane 13 wafers 14 wafer holders 15 wafer transfer drive 16 Lighting radiation 17 Collector 18 Intermediate focus plane 19 deflecting mirrors 20 first faceted mirror 21 first facet 22 second faceted mirror 23 second facet 30 mirrors 31 Mirror plate 32 Carrier plate 33 Base plate 34 Solid body joint 35 capacitive sensor 36 upper comb-shaped electrode 37 lower comb-shaped electrode 40 Data collection device 41 first sensor unit 42 second sensor unit 51 Control unit 52 Control unit 61 Resistance 62 Resistance 70 Investigation Unit 80 electrical conductors 90 evaluation units 300 Investigation Unit 310 analog part 311 Capacitor 312 amplifiers 313 Analog-to-Digital Converters 314 Overvoltage protection circuit 315 switches 320 digital part 321 Gradient Detection Unit 322 Transient detection unit 323 memory unit 324 filter unit 325 AND gate 326 N-bit comparator 327 Register 328 Latches 329 N-bit comparator 400 Investigation Unit 410 analog part 411 Resistance 412 Peak Value Detection Circuit 413 Capacitor 414 amplifiers 415 Analog-to-Digital Converters 416 Overvoltage protection circuit 417 high-impedance resistor 418 operational amplifiers 419 Diode 420 digital part 421 storage unit 500 Investigation Unit 510 analog part 511 Resistor 512 amplifiers 513 Analog-to-Digital Converters 520 digital part 521 Gradient Detection Unit 522 Logic circuit 523 memory unit 524 N-bit comparison unit 525 Register 526 AND gates 527 Address counter AS excitation signal f4 clock frequency f5 Clock frequency I Electricity K discrete-time tilt angle signal K1 Input node K2 output node K3 Input Node K4 Exit Node K5 Exit Node K6 Input node K7 Exit node M1-M6 mirrors MS measurement signal P indicative parameter value R1 first resistor R2 second resistor S radiation S1 first trigger signal S2 second trigger signal S3 control signal T1 first trigger signal T2 second trigger signal T3 output signal V1 voltage V2 amplified voltage signal V3 steady-state voltage V4 voltage V5 peak value V6 measuring voltage V7 amplified measuring voltage V8 digital voltage signal V9 voltage V10 amplified voltage signal V11 digital voltage signal V12 sampled time-dependent voltage curve W tilt angle

Claims

[1] Lithography system (1), with: a radiation source (3) for generating radiation (S) with a specific repetition frequency, and a mirror array with a plurality of mirrors (30), wherein the respective mirror (30) is set up to guide the radiation (S) in the lithography system (1) and has a mirror plate (31) that can be displaced by a tilting angle (W), wherein the respective mirror plate (31) is connected to a detection device (300) via an electrical conductor (80) for conducting the electric current (I) of the mirror plate (31) to the detection device (300), wherein the detection device (300) has a capacitor (311) coupled between the electrical conductor (80) and ground and is configured to determine a steady-state voltage value (V3) of the voltage drop (V1) across the capacitor (311) as an indicative parameter value (P) for the intensity of the radiation (S) incident on the mirror plate (31) using the electric current (I) conducted to the detection device (300). [2] Lithography system according to claim 1, further comprising an evaluation unit (90) which is configured to derive the electric charge that is replaced on the mirror plate (31) from the determined steady-state voltage value (V3) of the voltage (V1) dropping across the capacitor (311), and / or to determine the time-integrated intensity of the radiation (S) on the mirror plate (31) from the electric charge. [3] Lithography system according to claim 1 or 2, wherein the detection device (300) has an analog part (310) and a digital part (320), wherein the analog part (310) comprises: the capacitor (311) coupled between the electrical conductor (80) and ground, whose input node (K1) is connected to the electrical conductor (80) and whose output node (K2) is connected to ground, an amplifier (312) coupled to the input node (K1), which is configured to provide an amplified voltage signal (V2) based on the voltage drop (V1) across the capacitor (311), and an analog-to-digital converter (313) coupled to the amplifier (312), which is configured to convert the voltage signal (V2) provided by the amplifier (312) into a digital voltage signal (V3) with N bits. [4] Lithography system according to claim 3, wherein the digital part (320) comprises: a gradient detection unit (321) which is configured to detect a rising edge of the voltage (V1) across the capacitor (311) based on the digital voltage signal (V3) provided by the analog-to-digital converter (313) and, depending on this, to provide a first trigger signal (T1) upon detection of a rising edge, a transient detection unit (322) which is configured to provide a second trigger signal (T2) when a stable digital voltage signal (V3) is present within a certain tolerance range, and a storage unit (323) which is configured to store the digital voltage signal (V3) provided by the analog-to-digital converter (313) as the parameter value (P) indicative of the intensity of the radiation (S) directed onto the mirror plate (31) if the first trigger signal (T1) and the second trigger signal (T2) are provided. [5] Lithography system according to claim 4, wherein the digital part (320) of the detection device (300) comprises a filter unit (324) connected between the output of the analog-to-digital converter (313) and the storage unit (323), which is configured to filter the digital voltage signal (V3) provided by the analog-to-digital converter (313) and, based thereon, output a filtered digital voltage signal (V3) to the storage unit (323), wherein the storage unit (323) is configured to store the filtered digital voltage signal (V3) provided by the filter unit (324) as the indicative parameter (P) if an output signal (T3) of an AND gate (325) linking the first trigger signal (T1) and the second trigger signal (T2) has a positive signal state. [6] Lithography system according to claim 5, wherein the analog part (310) of the detection device (300) has a controllable switch (315) connected in parallel to the capacitor (311), by means of which the capacitor (311) can be discharged using the output signal (T3) of the AND gate (325), in particular after storage by the storage unit (323), and / or wherein the analog part (310) has an overvoltage protection circuit (314) connected between the input node (K1) and the amplifier (312). [7] Lithography system (1), with: a radiation source (3) for generating radiation (S) with a specific repetition frequency, and a mirror array with a plurality of mirrors (30), wherein the respective mirror (30) is set up to guide the radiation in the lithography system (1) and has a mirror plate (31) that can be displaced by a tilting angle (W), wherein the respective mirror plate (31) is connected to a detection device (400) via an electrical conductor (80) for conducting the electric current (I) of the mirror plate (31) to the detection device (400), wherein the detection device (400) has a resistor (411) coupled between the electrical conductor (80) and ground and is configured to determine a peak value (V5) of the voltage (V4) dropping across the resistor (411) as an indicative parameter value (P) for the intensity of the radiation (S) incident on the mirror plate (31) using the electric current (I) conducted to the detection device (400). [8] Lithography system according to claim 7, further comprising an evaluation unit (90) which is configured to derive the electric current (I) of the mirror plate (31) from the determined peak value (V5) of the voltage (V4) dropping across the resistor (411), and / or to determine the instantaneous value of the intensity of the radiation (S) on the mirror plate (31) from the electric current (I) of the mirror plate (31). [9] Lithography system according to claim 7 or 8, wherein the detection device (400) has an analog part (410) and a digital part (420), wherein the analog part (410) comprises: the resistor (411) coupled between the electrical conductor (80) and ground, whose input node (K3) is connected to the electrical conductor (80) and whose output node (K4) is connected to ground, a peak value detection circuit (412) coupled to the input node (K3), which is configured to provide a measuring voltage (V6) representing the peak value (V5) of the voltage (V4) dropping across the resistor (411) at its output node (K5), a capacitor (413) connected between the output node (K5) and ground to hold the measuring voltage (V6), an amplifier (414) coupled to the output node (K5), which is configured to amplify the measurement voltage (V6) held by the capacitor (413) and to provide an amplified measurement voltage (V7) on the output side depending on this, an analog-to-digital converter (415) coupled to the amplifier (414), which is configured to convert the amplified measurement voltage (V7) provided by the amplifier (414) into a digital voltage signal (V8) with N bits. [10] Lithography system according to claim 9, wherein the digital part (420) has a storage unit (421) which is configured to store the digital voltage signal (V8) provided by the analog-to-digital converter (415) as the parameter value (P) indicative of the intensity of the radiation (S) directed onto the mirror plate (31). [11] Lithography system according to any one of claims 7 to 10, wherein the amplifier (414) has a voltage divider (R1, R2) coupled between the output node (K5) and ground, with a first resistor (R1) and a second resistor (R2), wherein the peak detection circuit (412) comprises an operational amplifier (418) and a diode (419) connected downstream of the operational amplifier (418), wherein the non-inverting input of the operational amplifier (418) is connected to the input node (K3) and the inverting input of the operational amplifier (418) is connected to the center tap of the voltage divider (R1, R2). [12] Lithography system (1), with: a radiation source (3) for generating radiation (S) with a specific repetition frequency, and a mirror array with a plurality of mirrors (30), wherein the respective mirror (30) is set up to guide the radiation (S) in the lithography system (1) and has a mirror plate (31) that can be displaced by a tilting angle (W), wherein the respective mirror plate (31) is connected to a detection device (500) via an electrical conductor (80) for conducting the electric current (I) of the mirror plate (31) to the detection device (500), wherein the detection device (500) has a resistor (511) coupled between the electrical conductor (80) and ground and is configured to determine a sampled time-dependent voltage profile (V12) of the voltage (V9) dropping across the resistor (511) as an indicative parameter value (P) for the intensity of the radiation (S) incident on the mirror plate (31) using the electric current (I) conducted to the detection device (500). [13] Lithography system according to claim 12, further comprising an evaluation unit (90) which is configured to derive a time course of the electric current (I) of the mirror plate (31) from the sampled time course of the voltage (V12) of the voltage (V9) dropping across the resistor (511), and / or to determine a time course of the intensity of the radiation (S) on the mirror plate (31) from the time course of the electric current (I) of the mirror plate (31). [14] Lithography system according to claim 12 or 13, wherein the detection device (500) has an analog part (510) and a digital part (520), wherein the analog part (510) comprises: the resistor (511) coupled between the electrical conductor (80) and ground, whose input node (K6) is connected to the electrical conductor (80) and whose output node (K7) is connected to ground, an amplifier (512) coupled to the input node (K6) and an analog-to-digital converter (513) connected downstream of the amplifier (512) and operated at a specific clock frequency (f5), wherein the amplifier (512) is configured to amplify the voltage (V9) dropping across the resistor (511) and, depending on this, to provide an amplified voltage signal (V10) on the output side, wherein the analog-to-digital converter (513) is configured to convert the amplified voltage signal (V10) provided by the amplifier (512) into a digital voltage signal (V11) with N bits. [15] Lithography system according to claim 14, wherein the digital part (520) comprises: a gradient detection unit (521) operated at a specific clock frequency (f5), which is configured to detect a rising edge of the digital voltage signal (V11) provided by the analog-to-digital converter (513) and, based on this, to provide a first trigger signal (S1) upon detection of a rising edge, a logic circuit (522) which is configured to provide a second trigger signal (S2) based on an AND operation of the first trigger signal (S1) and the specified clock frequency (f5), and a storage unit (523) coupled to the output of the analog-to-digital converter (513), which is configured to store the digital voltage signal (V11) provided by the analog-to-digital converter (513) as a time- and value-discrete signal (V12) if the second trigger signal (S2) provided by the logic circuit (522) has a positive signal state. [16] Lithography system according to claim 15, wherein the specified clock frequency (f5) is greater than 100 MHz.

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