OPTICAL SYSTEM AND LITHOGRAPHING PLANT

Abstract

An optical system (300) for a lithography system, comprising a number N of printed circuit boards (500), wherein each printed circuit board (500) is assigned unique identification information, wherein each printed circuit board (500) comprises at least one identification circuit (510) for identifying the printed circuit board (500) with a circuit part (520) having a specific time constant, wherein at least part of the identification information can be derived from the specific time constant.

Description

[0001] The present invention relates to an optical system comprising a number of circuit boards and a lithography system comprising such an optical system.

[0002] Microlithography is used to manufacture microstructured components, such as integrated circuits. The microlithography process is carried out using a lithography system equipped with an illumination system and a projection system. The image of a mask (reticle) illuminated by the illumination system is projected by the projection system onto a substrate coated with a light-sensitive layer (photoresist) and arranged in the image plane of the projection system, for example, a silicon wafer, in order to transfer the mask structure to the light-sensitive coating of the substrate.

[0003] Driven by the pursuit of ever smaller structures in the production 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 at this wavelength, such EUV lithography systems must use reflective optics, i.e., mirrors, instead of the refractive optics, i.e., lenses, as was previously the case.

[0004] A variety of actuator / sensor devices, such as sensors and actuators, are installed in lithography systems. In general, an actuator / sensor device is suitable for displacing an optical element assigned to the actuator / sensor device, such as a mirror, and / or detecting a parameter of the assigned optical element, such as a position of the assigned optical element or a temperature of the assigned optical element. For control and evaluation, such an actuator / sensor device must be electrically connected to an integrated circuit (IC). Integrated circuits are assembled on printed circuit boards (also called printed circuit boards), and the assembled printed circuit boards are installed in the lithography system. The printed circuit boards must be provided with identification information, which includes, for example, an identification number of the printed circuit board and / or a version number.

[0005] Traditionally, the identification information is binary-encoded using resistors on the circuit board. With a large number of different pieces of identification information, this requires many resistors and many I / O ports on the evaluation unit that evaluates the identification information. The evaluation unit is implemented, for example, as an FPGA. One I / O port and two resistors are traditionally required per bit of coding. The resistors, however, take up a lot of space on the circuit board. Due to the high number of I / O ports occupied on the FPGA, other functionalities provided by the FPGA may no longer be able to be implemented.

[0006] Against this background, an object of the present invention is to provide an improved optical system.

[0007] According to a first aspect, an optical system for a lithography system is proposed. The optical system comprises a number N of circuit boards, where N ≥ 1, each circuit board being assigned unique identification information. Each circuit board comprises at least one identification circuit for identifying the circuit board with a circuit part having a specific time constant, wherein at least part of the identification information can be derived from the specific time constant.

[0008] In this case, the circuit board's identification information is encoded via the time constant of the circuit component of the identification circuit. The circuit component with the specific time constant is, for example, an RC element. For the RC element example, the time constant T of the circuit component is the product of the value of the resistance R and the value of the capacitance C: T = R · C

[0009] One can say that the time constant T consisting of R and C corresponds to a state. If the RC element in the resonant circuit of the identification circuit is excited, a defined frequency results. This frequency correlates with the time constant T and, like the time constant T, is indicative of the identification information of the circuit board. This frequency of the output signal of the identification circuit can be evaluated by the evaluation unit, which can infer the identification information from the frequency or time constant. For example, the frequency can be evaluated by the evaluation unit with a counter to determine a state. However, it is also possible to define the state and thus infer the identification information by evaluating the time constant alone. The identification information includes, for example, an identification number of the circuit board and / or a version number.

[0010] The optical system is preferably a projection optics system of the lithography system or projection exposure system. However, the optical system can also be an illumination system. The 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 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.

[0011] According to one embodiment, the circuit part having the specific time constant comprises an RC element, an RL element, and / or an LC element. The RC element is a circuit comprising at least one ohmic resistor R and a capacitor C. The RL element is a circuit comprising at least one resistor R and an inductor L. The LC element is a circuit comprising at least one inductor L and a capacitance C. Each of these circuit variants has a specific time constant, from which at least part of the identification information can be derived. At least part of the identification information can be derived from the specific time constant. If, for example, the circuit board only comprises one identification circuit, the complete identification information can be derived from the specific time constant of the circuit part of the identification circuit.In alternative embodiments in which the circuit board has a plurality M, with M ≥ 2, of identification circuits, the identification information of the circuit board is preferably composed of or derivable from the plurality M of different time constants.

[0012] According to a further embodiment, the identification circuit has an excitation unit configured to excite the circuit part using a specific excitation signal to provide an output signal with a defined frequency on the output side. The defined frequency of the output signal of the specific circuit part of the identification circuit is representative of the time constant of the identification circuit. Consequently, at least part of the circuit board's identification information can be derived from this defined frequency.

[0013] According to a further embodiment, the excitation unit is designed as an inverting Schmitt trigger. If the input voltage exceeds the upper switching source of the inverting Schmitt trigger, its output voltage switches from the maximum voltage value to the minimum voltage value.

[0014] However, if the input voltage subsequently falls below the lower switching threshold, the output voltage drops back to the maximum output voltage. The two switching thresholds are separated by a voltage difference, which can also be referred to as hysteresis.

[0015] According to a further embodiment, the optical system further comprises an evaluation unit which is configured to determine at least part of the identification information of the circuit board by means of the output signal provided by the identification circuit with the specific frequency.

[0016] According to a further embodiment, the identification circuit is connected to exactly one I / O port of the evaluation unit. According to a further embodiment, the identification circuit is connected to exactly two I / O ports of the evaluation unit.

[0017] The installation space in a lithography system is very limited. This also means that the installation space for the circuit boards to be installed is very limited. The present circuit board with its identification circuit is particularly advantageous compared to conventional circuit boards, in which the identification information is implemented using resistors, because more states can be implemented per installation space and required I / O ports of the evaluation unit. For example, with conventional circuit boards, 14 resistors and 7 I / O ports of the evaluation unit are required for 120 states. In contrast, the present embodiment, in which the specific circuit part is implemented as an RC element, requires only one resistor, one capacitor, and one inverting Schmitt trigger for 120 states. As explained above, only one I / O port is required in each case.This is shown by the table below, which illustrates the determination of various time constants using the E series of components. Variante E-Reihe Multiplikator Kapazität [F] Zeitkonstante [s] 1 1 100 1,00E-08 1,00E-06 2 1,1 100 1,00E-08 1,10E-06 3 1,2 100 1,00E-08 1,20E-06 4 1,3 100 1,00E-08 1,30E-06 5 1,5 100 1,00E-08 1,50E-06 6 1,6 100 1,00E-08 1,60E-06 7 1,8 100 1,00E-08 1,80E-06 8 2 100 1,00E-08 2,00E-06 9 2,2 100 1,00E-08 2,20E-06 10 2,4 100 1,00E-08 2,40E-06 11 2,7 100 1,00E-08 2,70E-06 12 3 100 1,00E-08 3,00E-06 13 3,3 100 1,00E-08 3,30E-06 14 3,6 100 1,00E-08 3,60E-06 15 3,9 100 1,00E-08 3,90E-06 16 4,3 100 1,00E-08 4,30E-06 17 4,7 100 1,00E-08 4,70E-06 18 5,1 100 1,00E-08 5, 10E-06 19 5,6 100 1,00E-08 5,60E-06 20 6,2 100 1,00E-08 6,20E-06 21 6,8 100 1,00E-08 6,80E-06 22 7,5 100 1,00E-08 7,50E-06 23 8,2 100 1,00E-08 8,20E-06 24 9,1 100 1,00E-08 9,10E-06 25 1 1000 1,00E-08 1,00E-05 26 1,1 1000 1,00E-08 1,10E-05 27 1,2 1000 1,00E-08 1,20E-05 28 1,3 1000 1,00E-08 1,30E-05 29 1,5 1000 1,00E-08 1,50E-05 30 1,6 1000 1,00E-08 1,60E-05 31 1,8 1000 1,00E-08 1,80E-05 32 2 1000 1,00E-08 2,00E-05 33 2,2 1000 1,00E-08 2,20E-05 34 2,4 1000 1,00E-08 2,40E-05 35 2,7 1000 1,00E-08 2,70E-05 36 3 1000 1,00E-08 3,00E-05 37 3,3 1000 1,00E-08 3,30E-05 38 3,6 1000 1,00E-08 3,60E-05 39 3,9 1000 1,00E-08 3,90E-05 40 4,3 1000 1,00E-08 4,30E-05 41 4,7 1000 1,00E-08 4,70E-05 42 5,1 1000 1,00E-08 5,10E-05 43 5,6 1000 1,00E-08 5,60E-05 44 6,2 1000 1,00E-08 6,20E-05 45 6,8 1000 1,00E-08 6,80E-05 46 7,5 1000 1,00E-08 7,50E-05 47 8,2 1000 1,00E-08 8,20E-05 48 9,1 1000 1,00E-08 9,10E-05 49 1 10000 1,00E-08 1,00E-04 50 1,1 10000 1,00E-08 1,10E-04 51 1,2 10000 1,00E-08 1,20E-04 52 1,3 10000 1,00E-08 1,30E-04 53 1,5 10000 1,00E-08 1,50E-04 54 1,6 10000 1,00E-08 1,60E-04 55 1,8 10000 1,00E-08 1,80E-04 56 2 10000 1,00E-08 2,00E-04 57 2,2 10000 1,00E-08 2,20E-04 58 2,4 10000 1,00E-08 2,40E-04 59 2,7 10000 1,00E-08 2,70E-04 60 3 10000 1,00E-08 3,00E-04 61 3,3 10000 1,00E-08 3,30E-04 62 3,6 10000 1,00E-08 3,60E-04 63 3,9 10000 1,00E-08 3,90E-04 64 4,3 10000 1,00E-08 4,30E-04 65 4,7 10000 1,00E-08 4,70E-04 66 5,1 10000 1,00E-08 5,10E-04 67 5,6 10000 1,00E-08 5,60E-04 68 6,2 10000 1,00E-08 6,20E-04 69 6,8 10000 1,00E-08 6,80E-04 70 7,5 10000 1,00E-08 7,50E-04 71 8,2 10000 1,00E-08 8,20E-04 72 9,1 10000 1,00E-08 9,10E-04 73 1 10000 1,00E-07 1,00E-03 74 1,1 10000 1,00E-07 1,10E-03 75 1,2 10000 1,00E-07 1,20E-03 76 1,3 10000 1,00E-07 1,30E-03 77 1,5 10000 1,00E-07 1,50E-03 78 1,6 10000 1,00E-07 1,60E-03 79 1,8 10000 1,00E-07 1,80E-03 80 2 10000 1,00E-07 2,00E-03 81 2,2 10000 1,00E-07 2,20E-03 82 2,4 10000 1,00E-07 2,40E-03 83 2,7 10000 1,00E-07 2,70E-03 84 3 10000 1,00E-07 3,00E-03 85 3,3 10000 1,00E-07 3,30E-03 86 3,6 10000 1,00E-07 3,60E-03 87 3,9 10000 1,00E-07 3,90E-03 88 4,3 10000 1,00E-07 4,30E-03 89 4,7 10000 1,00E-07 4,70E-03 90 5,1 10000 1,00E-07 5,10E-03 91 5,6 10000 1,00E-07 5,60E-03 92 6,2 10000 1,00E-07 6,20E-03 93 6,8 10000 1,00E-07 6,80E-03 94 7,5 10000 1,00E-07 7,50E-03 95 8,2 10000 1,00E-07 8,20E-03 96 9,1 10000 1,00E-07 9,10E-03 97 1 10000 1,00E-06 1,00E-02 98 1,1 10000 1,00E-06 1,10E-02 99 1,2 10000 1,00E-06 1,20E-02 100 1,3 10000 1,00E-06 1,30E-02 101 1,5 10000 1,00E-06 1,50E-02 102 1,6 10000 1,00E-06 1,60E-02 103 1,8 10000 1,00E-06 1,80E-02 104 2 10000 1,00E-06 2,00E-02 105 2,2 10000 1,00E-06 2,20E-02 106 2,4 10000 1,00E-06 2,40E-02 107 2,7 10000 1,00E-06 2,70E-02 108 3 10000 1,00E-06 3,00E-02 109 3,3 10000 1,00E-06 3,30E-02 110 3,6 10000 1,00E-06 3,60E-02 111 3,9 10000 1,00E-06 3,90E-02 112 4,3 10000 1,00E-06 4,30E-02 113 4,7 10000 1,00E-06 4,70E-02 114 5,1 10000 1,00E-06 5,10E-02 115 5,6 10000 1,00E-06 5,60E-02 116 6,2 10000 1,00E-06 6,20E-02 117 6,8 10000 1,00E-06 6,80E-02 118 7,5 10000 1,00E-06 7,50E-02 119 8,2 10000 1,00E-06 8,20E-02 120 9,1 10000 1,00E-06 9,10E-02

[0018] The first column of the table shows the 120 variants, the second column shows the respective E series, the third column shows the respective multiplier, the fourth row shows the capacitance value, and the fifth and final column shows the associated time constant. In total, the table shows that 120 different time constants can be realized.

[0019] According to a further embodiment, the evaluation unit is arranged on the circuit board.

[0020] According to a further embodiment, the evaluation unit is arranged externally of the circuit board.

[0021] According to a further embodiment, the optical system comprises a plurality N of circuit boards, with N ≥ 2.

[0022] According to a further embodiment, the complete identification information of the circuit board can be derived from the determined time constant of the circuit part of the identification circuit.

[0023] According to a further embodiment, the circuit board has a plurality of identification circuits. The identification circuits have different circuit components with different specific time constants, and the identification information of the circuit board can be derived from the different specific time constants.

[0024] According to one embodiment, the optical system is designed as an illumination optics or as a projection optics of a lithography system.

[0025] The optical system comprises in particular a micromirror array and / or a microlens array with a plurality of independently actuatable optical elements.

[0026] According to a further embodiment, the optical system comprises a vacuum housing in which the number N of circuit boards is arranged.

[0027] According to a second aspect, a lithography system is proposed which has an optical system according to the first aspect or according to one of the embodiments of the first aspect.

[0028] The lithography system is, for example, an EUV lithography system whose working light lies in a wavelength range from 0.1 nm to 30 nm, or a DUV lithography system whose working light lies in a wavelength range from 30 nm to 250 nm.

[0029] "One" in this case is not necessarily limited to a single element. Rather, multiple elements, such as two, three, or more, may also be included. Any other counting term used here should not be understood as implying a limitation to the exact number of elements stated. Rather, numerical deviations upwards and downwards are possible, unless otherwise stated.

[0030] Further possible implementations of the invention also include combinations of features or embodiments described above or below with respect to the exemplary embodiments that are not explicitly mentioned. In this case, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention.

[0031] 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 using preferred embodiments with reference to the accompanying figures. Fig. 1 shows a schematic meridional section of a projection exposure system for EUV projection lithography; Fig. 2 shows a schematic representation of an embodiment of an optical system; Fig. 3 shows a schematic representation of an embodiment of an optical system with a circuit board; and Fig. 4 shows a schematic representation of another embodiment of an optical system with a circuit board.

[0032] In the figures, identical or functionally equivalent elements are provided with the same reference numerals unless otherwise indicated. Furthermore, it should be noted that the representations in the figures are not necessarily to scale.

[0033] Fig. 1 shows an embodiment of a projection exposure system 1 (lithography system), in particular an EUV lithography system. One embodiment of an illumination system 2 of the projection exposure system 1 has, in addition to a light or radiation source 3, an illumination optics 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 remaining illumination system 2. In this case, the illumination system 2 does not include the light source 3.

[0034] A reticle 7 arranged in the object field 5 is exposed. The reticle 7 is held by a reticle holder 8. The reticle holder 8 can be displaced via a reticle displacement drive 9, in particular in a scanning direction.

[0035] In the Fig. For illustrative purposes, 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 scanning direction runs in the Fig. 1 along the y-direction y. The z-direction z runs perpendicular to the object plane 6.

[0036] The projection exposure system 1 comprises a projection optics 10. The projection optics 10 serves to image the object field 5 into an image field 11 in an image plane 12. The image plane 12 runs 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.

[0037] A structure on the reticle 7 is imaged onto a light-sensitive layer of a wafer 13 arranged in the image plane 12 in the region of the image field 11. The wafer 13 is held by a wafer holder 14. The wafer holder 14 can be displaced, in particular along the y-direction y, via a wafer displacement drive 15. The displacement of the reticle 7, on the one hand, via the reticle displacement drive 9, and the displacement of the wafer 13, on the other hand, via the wafer displacement drive 15, can be synchronized with each other.

[0038] The light source 3 is an EUV radiation source. The 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, in particular, a wavelength in the range between 5 nm and 30 nm. The 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. The light source 3 can be a free-electron laser (FEL).

[0039] 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 hyperboloidal reflection surfaces. The at least one reflection surface of the collector 17 can be exposed to the illumination radiation 16 at grazing incidence (GI), i.e., at angles of incidence greater than 45°, or at normal incidence (NI), i.e., at angles of incidence less than 45°. The collector 17 can be structured and / or coated, on the one hand, to optimize its reflectivity for the useful radiation and, on the other hand, to suppress stray light.

[0040] 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.

[0041] The illumination optics 4 comprises a deflecting mirror 19 and, downstream of this in the beam path, a first facet mirror 20. The deflecting mirror 19 can be a flat deflecting mirror or, alternatively, a mirror with a beam-influencing effect beyond the pure deflection effect. Alternatively or additionally, the deflecting mirror 19 can be designed as a spectral filter that separates a useful light wavelength of the illumination radiation 16 from stray light of a different wavelength. If the first facet mirror 20 is arranged in a plane of the illumination optics 4 that is optically conjugated to the object plane 6 as the field plane, it is also referred to as a field facet mirror. The first facet mirror 20 comprises a plurality of individual first facets 21, which can also be referred to as field facets. Of these first facets 21, Fig. 1 only some examples are shown.

[0042] The first facets 21 can be designed as macroscopic facets, in particular as rectangular facets or as facets with an arcuate or partially circular edge contour. The first facets 21 can be designed as flat facets or, alternatively, as convexly or concavely curved facets.

[0043] As is known, for example, from DE 10 2008 009 600 A1, the first facets 21 themselves can also 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.

[0044] Between the collector 17 and the deflecting mirror 19, the illumination radiation 16 runs horizontally, i.e. along the y-direction y.

[0045] In the beam path of the illumination optics 4, a second facet mirror 22 is arranged downstream of the first facet mirror 20. If the second facet mirror 22 is arranged in a pupil plane of the illumination optics 4, it is also referred to as a pupil facet mirror. The second facet 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 facet mirror 20 and the second facet 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 Pat. No. 6,573,978.

[0046] 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.

[0047] The second facets 23 can also be macroscopic facets, which can, for example, be round, rectangular, or hexagonal, or alternatively facets composed of micromirrors. Reference is also made to DE 10 2008 009 600 A1 in this regard.

[0048] The second facets 23 can have planar or alternatively convex or concave curved reflection surfaces.

[0049] The illumination optics 4 thus form a double-faceted system. This basic principle is also known as a fly's-eye integrator.

[0050] It may be advantageous to arrange the second facet mirror 22 not exactly in a plane that is optically conjugate to a pupil plane of the projection optics 10. In particular, the second facet 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.

[0051] With the help of the second facet mirror 22, the individual first facets 21 are imaged into the object field 5. The second facet mirror 22 is the last beam-forming mirror or actually the last mirror for the illumination radiation 16 in the beam path before the object field 5.

[0052] In a further embodiment of the illumination optics 4 (not shown), a transmission optics can be arranged in the beam path between the second facet mirror 22 and the object field 5, which transmission optics contributes in particular to the imaging of the first facets 21 into the object field 5. The transmission optics can have exactly one mirror, but alternatively also two or more mirrors, which are arranged one behind the other in the beam path of the illumination optics 4. The transmission optics can in particular comprise one or two mirrors for normal incidence (NI mirrors, normal incidence mirrors) and / or one or two mirrors for grazing incidence (GI mirrors, grazing incidence mirrors).

[0053] The illumination optics 4 has in the version shown in the Fig. 1, after the collector 17 there are exactly three mirrors, namely the deflection mirror 19, the first facet mirror 20 and the second facet mirror 22.

[0054] In a further embodiment of the illumination optics 4, the deflection mirror 19 can also be omitted, so that the illumination optics 4 can then have exactly two mirrors after the collector 17, namely the first facet mirror 20 and the second facet mirror 22.

[0055] The imaging of the first facets 21 by means of the second facets 23 or with the second facets 23 and a transmission optics into the object plane 6 is usually only an approximate imaging.

[0056] The projection optics 10 comprises a plurality of mirrors Mi, which are numbered according to their arrangement in the beam path of the projection exposure system 1.

[0057] In the Fig. In the example shown in Figure 1, the projection optics 10 comprises six mirrors M1 to M6. Alternatives with four, eight, ten, twelve, or a different number of mirrors M1 are also possible. The projection optics 10 is a doubly obscured optic. The penultimate mirror M5 and the last mirror M6 each have a passage opening 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.

[0058] Reflection surfaces of the mirrors Mi can be designed as freeform surfaces without a rotational symmetry axis. Alternatively, the reflection surfaces of the mirrors Mi can be designed as aspherical surfaces with exactly one rotational symmetry axis of the reflection 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.

[0059] 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.

[0060] The projection optics 10 can, in particular, be anamorphic. It has, in particular, different magnifications βx, βy in the x and y directions x, y. The two magnifications βx, βy of the projection optics 10 are preferably (βx, βy) = (+ / - 0.25, / +- 0.125). A positive magnification β means imaging without image inversion. A negative sign for the magnification β means imaging with image inversion.

[0061] The projection optics 10 thus leads to a reduction in the ratio 4:1 in the x-direction x, i.e. in the direction perpendicular to the scanning direction.

[0062] The projection optics 10 leads to a reduction of 8:1 in the y-direction y, i.e. in the scanning direction.

[0063] Other magnifications are also possible. Magnifications with the same sign and absolutely identical in the x and y directions (x, y), for example, with absolute values ​​of 0.125 or 0.25, are also possible.

[0064] 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 can be different, depending on the design of the projection optics 10. 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.

[0065] Each of the second facets 23 is assigned to exactly one of the first facets 21 to form a respective illumination channel for illuminating the object field 5. This can, in particular, result in illumination according to the Köhler principle. The far field is divided into a plurality of object fields 5 using the first facets 21. The first facets 21 generate a plurality of images of the intermediate focus on the second facets 23 assigned to them.

[0066] The first facets 21 are each imaged onto the reticle 7 by an associated second facet 23, superimposed on one another, to illuminate the object field 5. The illumination of the object field 5 is, in particular, as homogeneous as possible. It preferably has a uniformity error of less than 2%. Field uniformity can be achieved by superimposing different illumination channels.

[0067] By arranging the second facets 23, the illumination of the entrance pupil of the projection optics 10 can be geometrically defined. By selecting the illumination channels, in particular the subset of the second facets 23 that guide 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 fill.

[0068] A likewise preferred pupil uniformity in the area of ​​defined illuminated sections of an illumination pupil of the illumination optics 4 can be achieved by redistributing the illumination channels.

[0069] Further aspects and details of the illumination of the object field 5 and in particular of the entrance pupil of the projection optics 10 are described below.

[0070] The projection optics 10 can, in particular, have a homocentric entrance pupil. This can be accessible. It can also be inaccessible.

[0071] The entrance pupil of the projection optics 10 cannot usually be precisely illuminated with the second facet mirror 22. When imaging the projection optics 10, which images the center of the second facet mirror 22 telecentrically onto the wafer 13, the aperture rays often do not intersect at a single point. However, a surface can be found in which the pairwise determined distance of the aperture rays is minimized. This surface represents the entrance pupil or a surface conjugate to it in spatial space. In particular, this surface exhibits a finite curvature.

[0072] It is possible that the projection optics 10 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 facet mirror 22 and the reticle 7. With the help of this optical element, the different positions of the tangential entrance pupil and the sagittal entrance pupil can be taken into account.

[0073] In the Fig. In the arrangement of the components of the illumination optics 4 shown in Figure 1, the second facet mirror 22 is arranged in a surface conjugate to the entrance pupil of the projection optics 10. The first facet mirror 20 is arranged tilted relative to the object plane 6. The first facet mirror 20 is arranged tilted relative to an arrangement plane defined by the deflection mirror 19. The first facet mirror 20 is arranged tilted relative to an arrangement plane defined by the second facet mirror 22.

[0074] Fig. 2 shows a schematic representation of an embodiment of an optical system 300 for a lithography system or projection exposure system 1, as shown for example in Fig. 1. In addition, the optical system 300 of the Fig. 2 can also be used, for example, in a DUV lithography system.

[0075] The optical system 300 of the Fig. 2 has a plurality of actuatable optical elements 310. The optical system 300 is embodied here as a micromirror array, wherein the optical elements 310 are micromirrors. Each micromirror 310 is actuatable by means of an associated actuator 200. The actuator 200 is an example of an actuator / sensor device for actuating and / or sensing the optical elements 310. For example, a respective micromirror 310 can be tilted about two axes and / or displaced in one, two, or three spatial axes by means of the associated actuator 200. For reasons of clarity, the reference numerals are shown only for the top row of these elements.

[0076] The control device 100 controls the respective actuator 200, for example, with a control voltage V2. This adjusts a position of the respective micromirror 310. The control device 100 is supplied with electrical energy by a supply device 400. The supply device 400 provides the control device 100 with a supply voltage V1. The control device 100 is an example of a device of the optical system 300, which has a circuit board 500 or is implemented on a circuit board 500. Examples of an optical system 300 with a circuit board 500 are described with reference to Fig. 3 and Fig. 4 described.

[0077] Here the Fig. 3 is a schematic representation of an embodiment of an optical system 300 having a number N of circuit boards 500, where N ≥ 1. Without limiting the generality, N = 1 in the embodiment of the Fig. 3.

[0078] The circuit board 500 has unique identification information, in particular one-to-one identification information. The one-to-one identification information is, for example, a multi-digit identification number. The circuit board 500 comprises at least one identification circuit 510 for identifying the circuit board 500. Without limiting the generality, the circuit board 500 of the Fig. 3 a single identification circuit 510 for identifying the circuit board 500. The identification circuit 510 comprises a circuit part 520 having a specific time constant T. At least part of the identification information or the complete identification information can be derived from the specific time constant T. In the example of the Fig. 3, the circuit part 520 has an RC element with the resistor R and the capacitor C. The time constant T of an RC element consisting of the resistor R and the capacitor C is defined as: T = R · C

[0079] In time T, the capacitor has charged to 1-1 / e = 63.2% of the charging voltage or discharged to 1 / e = 36.8%. Since the time constant T depends on the values ​​of the resistance R and the capacitance C, the time constant T is specific to the design of the RC element of circuit part 520. Thus, by selecting the values ​​for R and C, the time constant T is suitable for forming specific identification information, via which the circuit board 500 can be uniquely and, in particular, uniquely identified.

[0080] In embodiments (not shown), the circuit part 520 having the specific time constant T comprises an RC element, an RL element comprising resistance R and inductance L and / or an LC element comprising inductance L and capacitance C.

[0081] As the Fig. 3 also shows, the identification circuit 510 also has an excitation unit 530. The excitation unit 530 is designed to control the circuit part 520, which in the embodiment according to Fig. 3 is designed as an RC element, by means of a specific excitation signal S1 to provide an output signal S2 with a defined frequency. Fig. 3 further shows, the excitation unit 530 can be designed as an inverting Schmitt trigger. The inverting Schmitt trigger 530 excites the RC element 520 of the Fig. 3 with the specific excitation signal S1, so that the RC element 520 provides the output signal S2 at the defined frequency on the output side. The specific time constant T of the RC element 520 can be derived from the defined frequency of the output signal S2, and thus at least part of the identification information of the circuit board 500 can also be derived from the defined frequency of the output signal S2.

[0082] As the Fig. As further shown in Figure 3, the optical system 300 also includes an evaluation unit 600. The circuit board 500 is arranged in particular in the vacuum housing of the optical system 300. The evaluation unit 600 can be arranged in the vacuum housing of the optical system 300. In alternative embodiments, the evaluation unit 600 can also be arranged outside the vacuum housing of the optical system 300. The evaluation unit 600 is configured to determine at least part of the identification information of the circuit board 500 using the output signal S2 provided by the identification circuit 510 at the specific frequency.

[0083] As the Fig. As shown in Figure 3, the identification circuit 510 of the circuit board 500 is connected to exactly two I / O ports 610, 620 of the evaluation unit 600. Further I / O ports of the evaluation unit are not shown for reasons of clarity. The output of the RC element 520 is connected to the I / O port 610 of the evaluation unit 600. The inverting Schmitt trigger 530 is controlled with an enable signal via the I / O port 620, so that it is triggered to output the specific excitation signal S1 to the RC element 520 on the output side.

[0084] In alternative embodiments not shown, the identification circuit 510 of the circuit board 500 can be connected to only a single I / O port of the evaluation unit 600, namely the I / O port 610. Enabling the non-inverting Schmitt trigger 530 via the evaluation unit 600 is therefore not necessary.

[0085] As already explained above, the evaluation unit 600 can be arranged internally in the vacuum housing (not shown) of the optical system 300 or externally in the vacuum housing of the optical system 300. In the case that the evaluation unit 600 is arranged within the vacuum housing, there are two possibilities: Firstly, that the evaluation unit 600 is arranged externally of the circuit board 500, for example on another circuit board, and furthermore, the possibility that the evaluation unit 600 is arranged on the circuit board 500 (not shown in Fig. 3) is arranged.

[0086] In alternative embodiments not shown, the optical system 300 may also comprise a plurality N of circuit boards 500, with N ≥ 2.

[0087] Furthermore, in embodiments, the complete identification information of the circuit board 500 can be derived from the determined time constant T of the circuit part 510 of the identification circuit 510. For example, the evaluation unit 600 can determine the complete identification information of the circuit board 500 from the output signal S2 provided by the identification circuit 510 at the determined frequency.

[0088] Fig. 4 shows a schematic representation of another embodiment of an optical system 300 with a circuit board 500. As the Fig. As shown in Figure 4, the circuit board has 500 of the Fig. 4 a plurality M of identification circuits 510. In general, the plurality M of identification circuits 510 is greater than or equal to 2 (M ≥ 2). In the embodiment according to Fig. 4, M = 4. The different identification circuits 510 have different circuit parts 510, different in the choice of values ​​for R and C. Thus, the different circuit parts 510, i.e. the different RC elements, have different determined time constants T. From these different determined time constants T, the evaluation unit 600 can derive the identification information of the circuit board 500.

[0089] As the Fig. 4 shows, the respective identification circuit 510 is coupled to two of the I / O ports 610 - 650 of the evaluation unit 600. As Fig. 3, it is sufficient in embodiments that the respective identification circuit 510 is connected to only one of the I / O ports 610 - 650 of the evaluation unit 600 (not shown).

[0090] Although the present invention has been described using exemplary embodiments, it can be modified in many ways. LIST OF REFERENCE SYMBOLS 1 projection exposure system 2 Lighting system 3 Light source 4 Lighting optics 5 Object field 6 Object level 7 reticles 8 reticle holders 9 Reticle displacement drive 10 Projection optics 11 Image field 12 Image plane 13 wafers 14 wafer holders 15 Wafer relocation drive 16 Illumination radiation 17 Collector 18 Intermediate focal plane 19 Deflecting mirrors 20 first facet mirror 21 first facet 22 second facet mirror 23 second facet 100 control device 200 actuator 300 optical system 310 optical element 400 supply facility 500 circuit boards 510 Identification circuit 520 circuit part 530 excitation unit 600 evaluation unit 610 I / O port 620 I / O port 630 I / O port 640 I / O ports 650 I / O ports C capacitor M1 mirror M2 mirror M3 mirror M4 mirror M5 mirror M6 mirror R resistance S1 excitation signal S2 output signal V1 input voltage V2 control voltage QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2008 009 600 A1 [0043, 0047] US 2006 / 0132747 A1

[0045] EP 1 614 008 B1

[0045] US 6,573,978

[0045] DE 10 2017 220 586 A1

[0050] US 2018 / 0074303 A1

[0064]

Claims

[1] Optical system (300) for a lithography system (1), with a number N of circuit boards (500), with N ≥ 1, wherein each circuit board (500) is assigned unique identification information, wherein each circuit board (500) comprises at least one identification circuit (510) for identifying the circuit board (500) with a circuit part (520) having a specific time constant, wherein at least part of the identification information can be derived from the specific time constant. [2] Optical system according to claim 1, wherein the circuit part (520) having the determined time constant comprises an RC element, an RL element and / or an LC element. [3] Optical system according to claim 1 or 2, wherein the identification circuit (510) has an excitation unit (530) which is configured to excite the circuit part (520) by means of a specific excitation signal (S1) for providing an output signal (S2) with a defined frequency on the output side. [4] Optical system according to claim 3, wherein the excitation unit (530) is designed as an inverting Schmitt trigger. [5] An optical system according to claim 3 or 4, further comprising: an evaluation unit (600) which is configured to determine at least part of the identification information of the circuit board (500) by means of the output signal (S2) provided by the identification circuit (510) with the specific frequency. [6] Optical system according to claim 5, wherein the identification circuit (510) is connected to exactly one I / O port (610) of the evaluation unit (600). [7] Optical system according to claim 5, wherein the identification circuit (510) is connected to exactly two I / O ports (610, 620) of the evaluation unit (600). [8] Optical system according to one of claims 5 to 7, wherein the evaluation unit (600) is arranged on the circuit board (500). [9] Optical system according to one of claims 5 to 7, wherein the evaluation unit (600) is arranged externally of the circuit board (500). [10] Optical system according to one of claims 1 to 9, wherein a plurality N of circuit boards (500) is provided, with N ≥ 2. [11] Optical system according to one of claims 1 to 10, wherein the complete identification information of the circuit board (500) can be derived from the determined time constant of the circuit part (520) of the identification circuit (510). [12] Optical system according to one of claims 1 to 10, wherein the circuit board (500) has a plurality of identification circuits (510), wherein the identification circuits (510) have different circuit parts (520) with different determined time constants, wherein the identification information of the circuit board (500) can be derived from the different determined time constants. [13] Optical system according to one of claims 1 to 12, wherein the optical system (300) is designed as an illumination optics (4) or as a projection optics (10) of a lithography system (1). [14] Lithography system (1) with an optical system (300) according to one of claims 1 to 13.

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