Illumination optical unit for projection lithography and method for monitoring such illumination optical unit

Abstract

An illumination optical unit (11) for projection lithography has a transmission facet mirror (6), an illumination specification facet mirror (7) and a monitoring device (28). The latter has at least one spatially resolved monitoring sensor (29) and a satellite facet (30), which belongs to the transmission facet mirror (6) and is assigned in each case to exactly one monitoring transmission facet (21). The orientation of the satellite facet (30) is such that the monitoring light (3) from the monitoring light source (2) is guided along the monitoring light channel (31) towards the monitoring sensor (29) through the satellite facet (30) and a lighting specification facet (25) to be monitored, which lighting specification facet (25) is assigned to the monitoring transmission facet (219). The result is an illumination optical unit in which the inclination of the illumination specification facets of an illumination specification facet mirror can be effectively monitored.

Description

Illumination optics unit for projection lithography and method for monitoring such illumination optics unit

[0001] This patent application claims priority to German patent application DE 10 2023 209 699.4, the contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to an illumination optical unit for projection lithography. Furthermore, this invention relates to a method for monitoring such an illumination optical unit, an optical system including such an illumination optical unit, a projection exposure apparatus including such an optical system, a method for producing microstructures or nanostructures using such a projection exposure apparatus, and a microstructure or nanostructure manufactured using this method. Background Technology

[0003] Illumination optics for projection lithography are known from DE 10 2015 208 512 A1 and the references cited therein. Summary of the Invention

[0004] The purpose of this invention is to develop an illumination optical unit of the type mentioned in the introduction so that the tilt of the illumination specification facet of the illumination specification facet mirror can be effectively monitored.

[0005] According to the present invention, this objective is achieved by an illumination optical unit comprising a monitoring device having the features specified in claim 1 and by a monitoring method having the features specified in claim 10.

[0006] According to the present invention, when using at least one satellite facet, the tilt of the illumination specification facet to be monitored is translated into a corresponding displacement of the monitoring optical channel guided by the corresponding satellite facet. These displacements of the monitoring optical channel can be detected by a sensor and are thus monitored as corresponding displacements of the incident position of the optical channel on the spatially resolved monitoring sensor of the monitoring device. The spatial difference between the target incident point of the monitoring optical channel and the actual incident point of the monitoring optical channel on the sensor is a measure of the tilt of the illumination specification facet to be monitored. In particular, mechanical drift of the illumination specification facet and / or, in the case of a corresponding actuator system for a given illumination specification facet, capacitive drift and / or thermal drift of the illumination specification facet can be effectively monitored in this way. The monitoring light source can be the same as the illumination light source (i.e., the light source that generates illumination light for projecting lithography). The transmission facet reflector can be arranged in the field plane of the beam path of the illumination light. Parallel processing of multiple monitoring optical channels can be provided by the monitoring device of the illumination optics unit, thereby simultaneously monitoring multiple illumination specification facets. The illumination specification facet reflector can be arranged in or near the pupil plane of the beam path of the illumination light. Alternatively, the illumination specification faceted reflector can be positioned at a certain distance from the pupil plane of the illumination beam path.

[0007] The transmission facets of the transmission facets of the reflector can be tilted by the actuator. This can be used to specify a corresponding illumination path for the illumination light, which in each case is guided to the object field through one of the transmission facets and through an illumination specification facet assigned to that transmission facet at a corresponding tilt position.

[0008] At least one monitoring sensor of the monitoring device can provide a sensor area in the range of 10 mm × 10 mm and 100 mm × 100 mm.

[0009] In particular, the light source that produces illumination can be used as a monitoring light source.

[0010] For example, the monitoring device may include 10,000 satellite facets.

[0011] The embodiment of the illumination optics unit as described in claim 2 is capable of monitoring a plurality of corresponding illumination specification surfaces assigned to satellite surfaces. Each illumination specification surface to be monitored can be assigned to the satellite surface of the monitoring device via a corresponding monitoring transmission surface. It is possible to monitor, in particular, all illumination specification surfaces of the illumination optics unit via the corresponding satellite surface of the monitoring device.

[0012] As described in claim 3, the spatial proximity between the corresponding satellite facet and the monitoring transmission facet assigned to it ensures that similar causes, such as drift due to far-field illumination from the transmission facet mirror, can be monitored. The distance between the satellite facet and the monitoring transmission facet assigned to the satellite facet can correspond to a typical extension of the transmission facet. When the transmission facet mirror is implemented in a modular manner, the satellite facet can be selected first, and the monitoring transmission facet assigned to the satellite facet can be selected second, such that the two facets belong to the same module of the transmission facet mirror.

[0013] Considering the corresponding installation space requirements, the arrangement of at least one monitoring sensor according to claim 4 has proven advantageous. Two monitoring sensors can be arranged adjacent to the respective shorter object field side, i.e., adjacent to the respective shorter field extension of the object field, such that the object field lies between the two monitoring sensors.

[0014] The design of the monitoring device with a separate monitoring light source according to claim 5 expands the processing possibilities of the monitoring device. The monitoring beam path of the independent monitoring light source can be coupled to the light guide of the illumination optics unit in the region of the central focal point. Alternatively or otherwise, the illumination light source can be used as the monitoring light source.

[0015] The monitoring light of multiple wavelengths as described in claim 6 enables parallel processing of monitoring light channels assigned to these wavelengths. In this case, at least one spectrally selective monitoring sensor can be used. A portion of the wavelength selective monitoring sensor can be a diffraction element, particularly a grating. Alternatively or additionally, a wavelength selective coating can be incorporated into the wavelength selective monitoring sensor, particularly an interference coating. The wavelength selective monitoring sensor can then be implemented with a filter that operates in a wavelength-dependent manner. Such a monitoring sensor can be implemented in the form of a Bayer sensor, i.e., in the form of an image sensor operating according to the concept of the Bayer matrix. Pixels of such an image sensor can be assigned to different colors within the wavelength range to be covered, similar to the RGB classification of the Bayer matrix.

[0016] The transmission faceted reflector and / or illumination specification faceted reflector as described in claim 7 can be implemented as a MEMS reflector. Subdividing the transmission faceted reflector and / or illumination specification faceted reflector into multiple individual reflectors, particularly into multiple individual reflectors of a MEMS reflector device, increases the flexibility of the illumination optics unit. The advantages of the monitoring device are particularly evident when monitoring the illumination specification faceted reflector, which is itself composed of multiple individual illumination specification reflectors.

[0017] With the aid of the monitoring device as described in claim 8, it is possible to monitor the effective tilt position of all individual lighting specification mirrors belonging to the lighting specification facet. In this case, these individual lighting specification mirrors can be scanned via a monitoring scanning unit.

[0018] The embodiment of the monitoring light source as a light source grid according to claim 9 enables parallel processing to detect the tilt of individual reflectors of the lighting specification facets to be monitored, as an alternative or additional monitoring possibility, rather than the monitoring scanning unit described above. In the case of the light source grid, parallel processing can then be performed by the monitoring device.

[0019] The advantages of the monitoring method as described in claim 10 correspond to the advantages explained above regarding the illumination optical unit including the monitoring device. Monitoring of the illumination specification facets to be monitored can be performed sequentially and / or in parallel. For monitoring, a monitoring scanning unit can be used to sequentially monitor the corresponding illumination specification facets and / or individual illumination specification mirrors, as already explained above. For monitoring, a light source grid for monitoring the light sources can be implemented, as also explained above, for monitoring the parallel tilt positions of multiple illumination specification facets and / or multiple individual illumination specification mirrors. For comparison, cross-correlation techniques can be used in the context of the monitoring method.

[0020] The monitoring method can be performed in parallel with the operation of the illumination optics unit. Alternatively or additionally, the monitoring method can be performed during a pause in the operation of the projection exposure equipment to which the illumination optics unit belongs. The monitoring method can be used to monitor, in particular, static alignment errors, manufacturing or indication faults, and general incorrect positions of the illumination specification facets to be monitored. Alternatively or additionally, dynamic tilt position deviations, such as the effects of thermal effects and / or changes in the illumination specification facets or facet actuator system due to use, can be monitored.

[0021] To measure and compare the incident point, diffraction effects occurring along the monitoring optical path can be considered.

[0022] The allocation method according to claim 11 specifies constraints that can improve the quality of monitoring results. As long as the minimum distance between the predetermined target incident points of different monitoring optical channels on the monitoring sensor is maintained, the corresponding monitoring optical channels can be reliably kept separate during the evaluation of the comparative results of the monitoring methods, thus allowing for unique allocation to the satellite facet, and consequently, to the illumination specification facet to be monitored. Maintaining the maximum distance between the satellite facet and the monitoring transmission facet allocated to the satellite facet ensures that the distance-related deviation between tilt positions has an undesirable impact on the satellite facet first, and secondly on the monitoring transmission facet allocated to the satellite facet.

[0023] The advantages of the optical system as claimed in claims 12 and 13, the projection exposure apparatus as claimed in claim 14, the manufacturing method as claimed in claim 15, and the microstructure or nanostructure component as claimed in claim 16 correspond to those advantages already explained above with reference to the illumination optical unit according to the invention and the monitoring method according to the invention.

[0024] The substrate can be a wafer. In particular, structured semiconductor devices, especially microchips, such as memory chips, can be fabricated. Attached Figure Description

[0025] Exemplary embodiments of the present invention will now be explained in more detail with reference to the accompanying drawings, in which:

[0026] Figure 1 schematically illustrates a projection exposure apparatus for EUV microlithography in a meridional section, which includes a light source, an illumination optics unit, and a projection optics unit, wherein a plan view of the object field of the projection exposure apparatus is shown in the inset.

[0027] Figure 2 schematically and similarly shows, in meridional section, the beam path of a selected individual illumination ray within the illumination optics unit according to Figure 1, from the central focal point to the mask master or object in the object plane of the projection optics unit arranged in the illumination or object field area.

[0028] Figure 3 shows a plan view of the first faceted mirror of the illumination optical unit, which is arranged in the field plane of the illumination optical unit and in the illumination far field of the light source, and is also referred to as the transmission faceted mirror or the field faceted mirror. It shows an array arrangement of individual mirror units, which in each case are formed by a sub-array of individual mirrors of the first faceted mirror (not visible in Figure 3).

[0029] Figure 4 still schematically shows, but in a magnified, exemplary and more detailed manner compared to Figure 3, one of the individual mirror units implemented as a sub-array of individual mirrors;

[0030] Figure 5 shows a plan view of the illumination specification faceted mirror of the illumination optical unit. This mirror is arranged at a certain distance from the pupil plane of the illumination optical unit and is also called the second faceted mirror.

[0031] Figure 6 schematically shows the illumination optical unit of the projection exposure device including the monitoring device, wherein the illumination channel illuminating the object via the transmission facet of the transmission facet and the illumination standard facet of the illumination standard facet is depicted in dashed lines, and the monitoring light channel illuminating the monitoring sensor of the monitoring device via the satellite facet of the transmission facet and the illumination standard facet of the illumination channel is depicted in solid lines.

[0032] Figure 7 shows another embodiment of the illumination optics unit of the components having another embodiment of the monitoring device, which includes a monitoring light source for monitoring light separate from the light source for illumination light, the monitoring light being guided along the monitoring light channel via the satellite facets of the transmission facets mirror;

[0033] Figure 8 shows a perspective view of another embodiment of an illumination optical unit with a monitoring device, the monitoring device comprising three monitoring light sources, each of which generates monitoring light of a specific wavelength, wherein the wavelengths generated by the monitoring light sources are different from each other;

[0034] Figure 9 illustrates another embodiment of a monitoring device with a monitoring scanning unit, similar to that in Figure 6, which is signal-connected to the actuator system of the satellite facet highlighted in Figure 9;

[0035] Figure 10 shows a plan view of the transmission faceted mirror in a similar diagram to Figure 3, highlighting the distribution of the transmission faceted mirrors used to set the illuminated object for a specific illumination and the transmission faceted mirrors not used for that illumination, which are distributed over the total usage area of ​​the transmission faceted mirror in each case.

[0036] Figure 11 shows the rectangular object field of the projection exposure device in this case in a plan view, and the corresponding sensor areas of the spatially resolved monitoring sensor of the monitoring device are shown on its right and left sides, wherein the incident point of the monitoring light channel in the sensor area is schematically shown in the manner of the monitoring light channel according to Figure 6.

[0037] Figure 12 shows one of the sensor areas of the monitoring device, which illustrates the distribution of the incident points of the monitoring optical channel as shown in Figure 11 after performing a method of assigning satellite facets to the illumination specification facets to be monitored, wherein the assignment method results in sufficient spatial distance between the incident points.

[0038] Figure 13 illustrates an embodiment of a monitoring device having a monitoring light source implemented as a light source grid, similar to the diagram according to Figure 9, wherein all light sources of the light source grid are activated, and wherein the monitoring light channel of the monitoring device originating from the center of the light source grid is shown.

[0039] Figure 14 illustrates the operation of the monitoring device according to Figure 13 in a similar manner to Figure 13, wherein only a single light source of the light source grid is active. Detailed Implementation

[0040] The microlithography projection exposure apparatus 1, shown schematically in a meridional section in Figure 1, has a light source 2 for illumination light 3. The light source 2 is an EUV light source that produces light in the wavelength range between 5 nm and 30 nm. This can be an LPP (laser-generated plasma) light source, a DPP (discharge-generated plasma) light source, or a synchrotron radiation-based light source, such as a free-electron laser (FEL).

[0041] The transmission optical unit 4 is used to guide the illumination light 3 emitted from the light source 2. This transmission optical unit has a light collector 5 and a transmission surface-mount mirror 6. The light collector 5 is shown only for its reflection effect in Figure 1, and the transmission surface-mount mirror 6 is described in more detail below and is also referred to as a first surface-mount mirror or a field surface-mount mirror. The intermediate focal point 5a of the illumination light 3 is arranged between the light collector 5 and the transmission surface-mount mirror 6. The numerical aperture of the illumination light 3 in the region of the intermediate focal point 5a is, for example, NA = 0.182. The illumination specification surface-mount mirror 7 (also referred to as a second or another surface-mount mirror and described in more detail below) is located downstream of the transmission surface-mount mirror 6, and therefore downstream of the transmission optical unit 4. Optical components 5 to 7 are part of the illumination optical unit 11 of the projection exposure apparatus 1.

[0042] The transmission faceted reflector 6 is arranged in the field plane of the illumination optical unit 11.

[0043] The illumination specification faceted mirror 7 of the illumination optical unit 11 is arranged at a certain distance from the pupil plane of the illumination optical unit 11. Such an arrangement is also referred to as a specular reflector. Alternatively, the illumination specification faceted mirror 7 may also be arranged in the region of the pupil plane of the illumination optical unit 11, and in this case it is referred to as a pupil faceted mirror.

[0044] The mask master 12 is positioned downstream of the illumination specification facet mirror 7 in the beam path of the illumination light 3, and is arranged in the object plane 9 of the downstream projection optics unit 10 of the projection exposure apparatus 1. The projection optics unit 10 is a projection lens. The illumination optics unit 11 is used to illuminate the object field 8 on the mask master 12 in the object plane 9 in a defined manner. The object field 8 also constitutes the illumination field of the illumination optics unit 11. Typically, the illumination field is configured such that the object field 8 can be arranged within the illumination field.

[0045] Similar to the transmission faceted mirror 6, the illumination specification faceted mirror 7 is also part of the pupil illumination unit of the illumination optics unit, used to illuminate the incident pupil 12a in the pupil plane 12b of the projection optics unit 10 with illumination light 3 having a specified pupil intensity distribution. The incident pupil 12a of the projection optics unit 10 can be arranged in the illumination beam path upstream or downstream of the object field 8.

[0046] Figure 1 shows the case where the incident pupil 12a is positioned in the illumination beam path downstream of the object field 8. In this case, the pupil distance PA between the second faceted mirror 7 and the pupil plane 12b is the sum of the z-distance PA1 between the second faceted mirror 7 and the object plane 9 and the z-distance PA2 between the object plane 9 and the pupil plane 12b. Therefore, PA = PA1 + PA2 holds. Alternatively, the pupil distance PA can also be measured in the beam direction.

[0047] For ease of representation of positional relationships, a Cartesian xyz coordinate system is used below. In Figure 1, the x-direction extends perpendicularly into the plane of the figure. The y-direction extends to the right in Figure 1. The z-direction extends downwards in Figure 1. The coordinate system used in the figures has x-axis axes that extend parallel to each other in each case. The z-axis of the coordinate system follows the respective principal directions of the illumination light 3 within the figure under consideration.

[0048] The object field 8 has an arcuate or partially circular shape, defined by two parallel circular arcs and two straight side boundaries. These two straight side boundaries extend in the y-direction for a length of y0 and are separated by a distance x0 from each other in the x-direction. The aspect ratio x0 / y0 is 13:1. The inset in Figure 1 shows a plan view of the object field 8, which is not drawn to scale. The boundary shape 8a is arcuate. In an alternative and equally possible object field 8, its boundary shape is rectangular, also with an aspect ratio x0 / y0.

[0049] The mask master 12 is displaced along the object displacement direction y through the object field 8 during projection exposure.

[0050] The projection optics unit 10 is shown only partially and schematically in FIG. 1. The object-side numerical aperture 13 and the image-side numerical aperture 14 of the projection optics unit 10 are shown. The image-side numerical aperture 14 can be in the range of 0.2 to 0.8, and can be, for example, 0.3, 0.33, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, or 0.75. Other optical components (not shown in FIG. 1) of the projection optics unit 10 for guiding the illumination light 3 between the shown optical components 15 and 16 are located between these optical components 15 and 16, and can be implemented as, for example, mirrors reflecting the EUV illumination light 3.

[0051] The projection optics unit 10 images the object field 8 onto the image field 17 in the image plane 18 on the wafer 19, which, like the mask master 12, is supported by a holder (not shown in more detail). Both the mask master holder and the wafer holder can be displaced in the x and y directions by corresponding displacement actuators. The mounting space requirement for the wafer holder is shown as a rectangular box 20 in FIG. 1. The mounting space requirement 20 is a cuboid, the extent of which in the x, y, and z directions depends on the components to be housed therein. The mounting space requirement 20 extends, for example, 1 m in the x and y directions from the center of the image field 17. In the z direction, the mounting space requirement 20 also extends, for example, 1 m from the image plane 18. The illumination light 3 must be guided in the illumination optics unit 11 and the projection optics unit 10 such that it is guided through the mounting space requirement 20 in each case.

[0052] The transmission faceted mirror 6 has multiple transmission facets 21, also referred to as first facets. The transmission faceted mirror 6 can be implemented as a MEMS mirror. The transmission facets 21 are individual transmission mirrors ES (see, for example, Figures 7 and 8), which can be switched between at least two tilt positions and implemented as micromirrors. The transmission facets 21 can be implemented as micromirrors that can be tilted in a driven manner about two mutually perpendicular rotation axes.

[0053] Of these transmission facets 21, a line with a total of nine transmission facets 21 is schematically shown in the yz cross-sectional view according to FIG. 2, the transmission facets being indexed from left to right in FIG. 2 from 211 to 219. In reality, the transmission facet mirror 6 has significantly more transmission facets 21. Transmission individual mirrors ES are grouped as transmission facets 21 (for this purpose, see also FIG. 7 and FIG. 13, for example). These transmission facets 21 are also referred to as individual mirror groups, virtual field facets, or virtual facet groups.

[0054] Each transmission plane 21 guides a component of the illumination light 3 (also called the illumination light component beam) via the illumination channel to partially or completely illuminate the object field 8. The illumination light component beam 3 is guided through this illumination channel and the illumination light component beam 3. i In each case, exactly one illumination specification plane 25 of the illumination specification plane mirror 7 is assigned to one of the individual mirror groups or the transmission plane 21. In principle, each of the illumination specification planes 25 can itself be constructed from multiple individual mirrors ES (see, for example, Figure 7). The illumination specification plane 25 is also referred to hereinafter as the second plane. When the second plane mirror 7 is arranged in the region of the pupil plane of the illumination optical unit 11, the illumination specification plane 25 is also referred to as the pupil plane.

[0055] The individual mirror group or transmission plane 21 is a group of individual mirrors ES of the first plane mirror 6, which are imaged to the object field 8 by the same second plane 25.

[0056] For further details regarding possible embodiments of the transmission faceted reflector 6 and the projection optical unit 10, refer to WO2010 / 099 807 A.

[0057] The illumination specification facet 7 is part of an optical unit, through which the transmission facet 21 is imaged at least into a portion or local field of the object field 8. At least some illumination specification facets 25 may illuminate only a portion of the object field 8 or a portion of the field. This portion of the field is shaped very individually and further depends on the desired illumination direction distribution (pupil shape) in the object field 8, i.e., the illumination setting. The illumination specification facets 25 are therefore illuminated by virtual field facets of very different shapes, whose shapes precisely correspond to the shapes of the corresponding portions of the field to be illuminated. Furthermore, each illumination specification facet 25 contributes to a different region of the pupil depending on its position in the object field 8.

[0058] The illumination specification facet 7 can be implemented as a MEMS mirror, particularly if each of the illumination specification facets 25 is constructed from multiple individual mirrors ES. The illumination specification facet 25 is a micromirror that can be switched between at least two tilt positions. The illumination specification facet 25 is implemented as a micromirror that can be tilted in two dimensions and driven to tilt about two mutually perpendicular tilt axes, particularly in a continuous and independent manner, i.e., the micromirror can be positioned to multiple different tilt positions.

[0059] An example of the designated allocation of individual transmission facets 21 to 219 to lighting specification facets 25 is illustrated in Figure 2. The lighting specification facets 25 assigned to transmission facets 211 to 219 in each case are indexed according to this allocation. Due to this allocation, the lighting specification facets 25 are illuminated from left to right in the following order: 256, 258, 253, 254, 251, 257, 255, 252, and 259.

[0060] Indices 6, 8, and 3 of facets 21 and 25 contain three illumination channels VI, VIII, and III, which illuminate three object points OF1, OF2, and OF3 from a first illumination direction, the object points being numbered from left to right in Figure 2. Indices 4, 1, and 7 of facets 21 and 25 belong to three additional illumination channels IV, I, and VII, illuminating the three object points OF1 to OF3 from a second illumination direction. Indices 5, 2, and 9 of facets 21 and 25 relate to three additional illumination channels V, II, and IX, illuminating the three object points OF1 to OF3 from a third illumination direction. Illumination channels I to IX are assigned corresponding illumination light component beams 31 to 39.

[0061] Assign lighting to the following directions:

[0062] -Lighting channels VI, VIII, III,

[0063] - Illumination channels IV, I, VII and

[0064] - Illumination channels V, II, IX

[0065] The same applies in every case. Therefore, the allocation of the transmission plane 21 to the illumination specification plane 25 results in telecentric illumination of the object field 8 in the case of the illustrated illumination example.

[0066] The object field 8 can be illuminated via a transmission faceted reflector 6 in the form of a specular reflector and an illumination specification faceted reflector 7. The principle of the specular reflector is known from US 2006 / 0132747 A1.

[0067] Figure 3 shows a plan view of one embodiment of the first faceted reflector 6. The latter has a regular array arrangement of individual reflector units 26, which are defined by squares in Figure 3. Each individual reflector unit 26 is implemented as a subarray of N × M individual reflectors ES. This subarray has multiple array lines that extend along line directions corresponding to the angle bisectors of the xy coordinate system.

[0068] Some adjacent array lines are offset from each other by a portion of the extension of one of the individual mirror units 26, specifically half of that extension of the respective individual mirror unit 26 along the array line. According to the embodiment of the faceted mirror 6, this offset can be managed entirely without it, thus resulting in an array arrangement constructed entirely of rows and columns. Alternatively, all array lines may be offset from each other. Different absolute offset values ​​between different adjacent array portions are also possible according to the embodiment of the faceted mirror 6 and depending on the requirements for positioning the individual mirror units 26.

[0069] The first faceted reflector 6 is arranged in the far-field usage area of ​​the light source 2.

[0070] Figure 4 schematically, but in more detail, shows one of the individual mirror units 26. The figure shows that in this case, the individual mirror unit 26 is subdivided into a 6 × 6 subarray of individual mirrors ES. Therefore, in the illustrated embodiment, each individual mirror unit 26 has 36 individual mirrors ES. Thus, N=6 and M=6 are suitable for the N × M subarray arrangement according to the example in Figure 4. N and M can be the same, can be different, and can each be in the range of 2 to 64, for example, 4, 8, 16, 32, or 64. Values ​​for N and M other than powers of 2 are also possible, such as 25 or 50. For example, 12 × 12 or 24 × 24 subarrays are also possible.

[0071] In the embodiment shown in FIG3, the first faceted mirror 6 has an arrangement of individual mirror units 26 within a circular envelope. Alternatively, the first faceted mirror 6 may also be comprised of individual mirror units 26 within an envelope having elliptical, rectangular, or polygonal boundaries.

[0072] In each case, one of the individual mirror units 26 may contain multiple complete or partial individual mirror groups that guide the illumination light 3 to different second facets 25 and image it into the object field 8 in a superimposed manner. Individual mirror groups (i.e., transmission facets 21) may extend over multiple individual mirror units 26.

[0073] Figure 5 again shows an embodiment of the second faceted reflector 7 in a plan view.

[0074] Each of the second facets 25 of the second faceted reflector 7 is implemented as having a circular boundary and existing in a hexagonal close-packed form. Second facets 25 with rectangular or polygonal boundaries, particularly hexagonal boundaries, are also alternatives to second facets 25 with circular boundaries. The second facet 25 can further be embodied as a single reflector unit in the style of a single reflector unit of the first faceted reflector 6, and in this case, can be subdivided into multiple single reflectors in the style of single reflector ES. In principle, the structure of the second faceted reflector 7 can correspond to the structure of the first faceted reflector 6 regarding subdivision into single reflectors and single reflector units.

[0075] In the embodiment according to FIG5, each of the second facets 25 may also be implemented as a global facet.

[0076] In the second faceted reflector 7, the second facet 25 is arranged within an envelope with an elliptical boundary. Alternatively, other envelope shapes are also possible, such as a circular envelope, a rectangular envelope, and an envelope with a polygonal boundary.

[0077] Figure 6 schematically shows one embodiment of the illumination optical unit 11. Components and functions corresponding to those explained above with reference to Figures 1 to 5 have the same reference numerals and will not be discussed in detail thereafter.

[0078] Figure 6 shows, in dashed lines, the path of the illumination channel 27 between the light source 2 or intermediate focal point 5a, the selected transmission surface 21 of the transmission surface mirror 6, the illumination specification surface 25 assigned to this transmission surface 21, and the object field 8 on the mask master 12. The illumination specification surface 25 is assigned to the monitoring surface 21 via the illumination channel 27. The transmission surface 21 is transferred to the object field 8 via the illumination channel 27, such that the illumination channel 27 illuminates the entire object field 8 or a portion of the object field 8, depending on the grouping selection of the individual mirrors ES belonging to the corresponding transmission surface 21 as separate mirror groups. This grouping of the individual mirrors ES (particularly resulting in the edge contour of the transmission surface 21 according to Figure 6) is not shown in Figure 6.

[0079] Figure 6 further illustrates the monitoring device 28 of the illumination optics unit 11. The monitoring device 28 includes a spatially resolved monitoring sensor 29, which is implemented as a PSD, CMOS, or CCD array having multiple sensor pixels (e.g., 10000 × 10000 sensor pixels). The spatially resolved monitoring sensor 29 may also have a significantly smaller number of sensor pixels, such as 10 × 10, 100 × 100, or 1000 × 1000. Aspect ratios different from the multiple pixels are also possible. Typically, a quadrant detector can also be used as the monitoring sensor 29.

[0080] The monitoring device 28 also includes a satellite facet 30, which may be, for example, exactly one or more selected individual mirrors of the transmission facet mirror 6. The satellite facet 30 can be independently tilted by an actuator about a tilt axis parallel to the coordinates x and y.

[0081] Figure 6 shows the monitoring light channel 31 from the light source 2 or intermediate focal point 5a via the satellite plane 30, the illumination specification plane 25 (which simultaneously guides the illumination channel 27 according to Figure 6) to the incident point or incident area 32 on the monitoring sensor 29. The typical diameter of the incident point of the monitoring light channel 31 on the monitoring sensor 29 can be 1 mm.

[0082] The object field 8 has a longer field extension along the x-field dimension and a shorter field extension along the y-field dimension. The monitoring sensor 29 is arranged at a distance from the object field 8 along the x-field dimension, and in the embodiment shown in FIG. 6, is located to the right of the shorter object field side of the object field 8. The monitoring sensor 29 may be arranged in the object plane 9; however, this is not mandatory. The monitoring sensor 29 may also be arranged at a distance from the object plane 9, for example—closer to the illumination specification faceted reflector 7 than to the mask master 12—or alternatively, further away from the latter.

[0083] Because it is guided via the same illumination specification plane 25, the satellite plane 30 is assigned to the transmission plane 21 highlighted in FIG. 6, which thus constitutes the monitoring transmission plane 21. This assignment requires the orientation of the satellite plane 30 so that the monitoring light (in this case, the illumination light 3 generated by the light source 2) is guided from the light source 2, which also constitutes the monitoring light source, via the satellite plane 30 and the illumination specification plane 25 highlighted in FIG. 6 as the illumination specification plane to be monitored, along the monitoring light path 31 to the monitoring sensor 29.

[0084] Simultaneously, the tilting drx and dry of the illumination specification surface 25 of the guiding illumination channel 27 and the monitoring light channel 31 causes displacement of the illumination channel 27 and the monitoring light channel 31, namely, displacement dx along the x-coordinate and displacement dy along the y-coordinate. The corresponding displacements dx and dy on the monitoring sensor 29 are measures of the tilting dry and drx of the illumination specification surface 25 to be monitored about tilt axes parallel to the coordinate axes x and y. Therefore, dy = f(drx) and dx = f(dry) hold.

[0085] Based on the target incident point 32 S (For example, predetermined during calibration) and the actual incident point 32 measured on the monitoring sensor 29 by the monitoring optical channel 31 respectively. I The displacements dx and dy between the two points (which can be measured by monitoring sensor 29) can be used to infer the actual tilt dry and drx of the monitored lighting specification facet 25.

[0086] When monitoring the illumination specification plane 25 of the illumination specification plane reflector 7 using the monitoring device 28, the following procedure can be used:

[0087] First, satellite facet 30 is assigned to the illumination specification facet 25 to be monitored. This may include assigning satellite facet 30 to transmission facet 21, which first illuminates the same illumination specification facet 25 to be monitored via transmission facet 21 and illumination channel 27 used in the projection exposure, and then via satellite facet 30 and monitoring light channel 31.

[0088] According to the constraints of the allocation steps, the satellite facet 30 can be closely adjacent to the monitoring transmission facet 21 to which it is allocated. The maximum distance that can be specified here can be, for example, the typical size of the monitoring transmission facet 21. For example, the allocation can be made under the constraint that the satellite facet 30 to be allocated exists on the same individual mirror unit 26 as the multiple individual mirrors ES of the monitoring transmission facet 21 to be allocated. As long as the spatial relationship between the monitoring transmission facet and the satellite mirror is sufficiently known, multiples of the typical size of the monitoring transmission facet can also be used in this method. Thus, a set of individual mirrors can also be used as the monitoring transmission facet 21. As an advantage, the larger distance between the satellite facet 30 and the monitoring transmission facet 21 to which it is allocated, in turn, allows the monitoring sensor 29 to be integrated into a scanner remote from the mask master 12.

[0089] After allocation, the monitoring light, i.e., illumination light 3, is guided along the monitoring light channel 31 via the corresponding satellite facet 30 and the allocated illumination specification facet 25, and the actual incident point 32 of the monitoring light channel 31 on the monitoring sensor 29 is measured in a spatially resolved manner. i Then the actual incident point 32 I At the predetermined target incident point 32 S Compare them.

[0090] This comparison is performed using the evaluation device 33 of the illumination optics unit 11. The evaluation device 33 is signal-connected to the central control device 34 of the projection exposure equipment 1.

[0091] Based on the comparison results of the monitoring methods, compensation measures can be initiated. This can be achieved through control device 34. Thermal or mechanical compensation measures can be implemented as long as the displacement of the incident point can be attributed to thermal drift.

[0092] Figure 7 shows another embodiment of the monitoring device 35, which can be used as an alternative or supplement to the monitoring device 28 in the corresponding embodiment of the illumination optical unit 11 of the projection exposure device 1. Components and functions corresponding to those explained above with reference to Figures 1 to 6, and especially to Figure 6, have the same reference numerals and will not be discussed in detail thereafter.

[0093] The illumination optical unit 11, as illustrated in Figure 7, is a specular reflector. By way of example, the principal ray 36, along with rim rays 37 and 38, which define the illumination angle distribution to one side and to the other side, are guided by individual mirrors ES of the illumination specification faceted reflector 7. This is illustrated in the basic schematic diagram according to Figure 7 by the fact that the principal ray 36 meets at the center of the entrance pupil 12a of the illumination optical unit 11. Therefore, the rim rays 37 and 38 first meet at opposite edge points of the entrance pupil 12a in the beam path of the illumination light 3 downstream of the object field 8.

[0094] The illumination specification faceted reflector 7 is arranged at a distance from the incident pupil plane 12b of the projection optical unit 10, not shown in Figure 7. The incident pupil 12a of the projection optical unit 10 cannot be used as the arrangement plane of the illumination specification faceted reflector 7 because it is located in the beam path downstream of the object field 8.

[0095] Figure 7 also shows two illumination channels 271 and 272 for the illumination mask master 12, each defined by two separate rays. Illumination channel 271 is defined by one of the principal rays 36 and one of the rim rays 37. Illumination channel 271 originates from the central focal point 5a and is guided to the object field 8 via the transmission plane 211 and the illumination specification plane 251. Illumination channel 272 (which is in turn defined by the principal ray 36 and the rim rays 38 assigned to opposite illumination angles) is guided to the object field 8 via the transmission plane 212 and the illumination specification plane 252.

[0096] Transmission planes 211 and 212 are formed by a group of individual mirrors ES of transmission plane reflector 6. For example, 14 × 6 individual mirrors are selected in the illustration. Other groups are also possible, particularly groups with several to several hundred individual mirrors.

[0097] Illumination specification facet 251 is formed by 2 × 2 individual mirrors ES of illumination specification facet mirror 7. In contrast, illumination specification facet 252 is formed by 4 × 4 individual mirrors ES of illumination specification facet mirror 7. Depending on the image shape and scale of the plasma image of light source 2, illumination specification facets can also be assembled from other numbers or groups of individual mirrors; in particular, 3 × 3, 5 × 5, 6 × 6, or 7 × 7 individual mirrors. Furthermore, it may be advantageous to use non-square groups, such as 3 × 4, 3 × 5, 4 × 5, 4 × 6, 4 × 7, 5 × 7, or 6 × 7 individual mirrors. In the case shown in Figure 7, illumination specification facet 252 is significantly larger than illumination specification facet 251.

[0098] The monitoring device 35 according to Figure 7 has a monitoring light source 39 that is separate from the illumination light source 2. This monitoring light source can be implemented, for example, as a laser diode.

[0099] The monitoring light source 39 is configured such that, in principle, the entire transmission surface reflector 6 can be illuminated by the light source. A wavelength conversion screen 40 is arranged in the beam path of the monitoring light source 39.

[0100] The monitoring light source 39 can be a monochromatic laser diode. The wavelength conversion screen 40 can be a fluorescent screen, such as a screen containing YAG aluminum phosphor.

[0101] The monitoring device 35 has two monitoring sensors 291 and 292, which are arranged at a certain distance on both sides of the object field 8 in the x-coordinate direction (i.e., perpendicular to the object displacement direction y of the projection exposure device 1). In addition, another monitoring sensor 29 can be arranged at a certain distance from each other in the x-direction. i This increases the effective usable sensor area of ​​the monitoring device 35 and allows for the simultaneous measurement of more illumination specification surfaces. Furthermore, a monitoring sensor 29 can be positioned at a specific distance from the object field 8 along the object displacement direction y.

[0102] Figure 7 shows the monitoring optical channel 31 between the wavelength conversion screen 40, the satellite facet 30, the illumination specification facet 252, and the monitoring sensor 292 of the monitoring device 35. The satellite facet 30 is designed to transmit the individual reflector ES on the facet reflector 6.

[0103] Since they are irradiated on the same illumination specification plane 252, the monitoring light channel 31 shown in FIG7 and the satellite plane 30 irradiated by the channel are assigned to the illumination channel 272, and thus to the monitoring transmission plane 212 and the illumination specification plane 252 to be monitored.

[0104] As explained above in connection with the embodiment according to FIG6, the tilt drx, dry of the illumination specification plane 252 is converted into the displacement dy, dx of the incident point 32 of the monitoring light channel 31 on the monitoring sensor 292.

[0105] The appropriate tilt angle allocation of the individual reflector ES on the faceted reflectors 6 and 7 ensures that the monitoring light 41 of the monitoring light source 39 does not undesirably illuminate the object field 8.

[0106] Referring to FIG8, another embodiment of the illumination optical unit 11 and the monitoring device 42 is described below, which can be used as an alternative or supplement to the monitoring devices 28 and 35 described above. Components and functions corresponding to those explained above with reference to FIGS. 1 to 7, and especially with reference to FIGS. 6 and 7, have the same reference numerals and will not be discussed in detail hereafter.

[0107] The components or functional units of the illumination optics unit 11 shown in Figure 8 are the central focal point 5a, the transmission faceted mirror 6, the illumination specification faceted mirror 7, and the bow-shaped object field 8 in this case. The schematic perspective view in Figure 8 shows an exemplary arrangement of the individual mirrors ES of the transmission faceted mirror 6 and the illumination specification faceted mirror 7.

[0108] Two transmission surfaces 211 and 212, each constructed from a set of 18 individual mirrors ES, are prominently displayed on the transmission surface mirror 6. The allocation of the individual mirrors ES to the corresponding transmission surfaces 211, 212 is such that the envelopes of these transmission surfaces 211, 212 are adapted in shape to the arc of the object field 8. The illumination channel, not shown in detail, guides illumination light from the intermediate focal point 5a in a superimposed manner through transmission surface 211 and illumination specification surface 251 allocated to the illumination specification surface mirror 7, and through transmission surface 212 and illumination specification surface 252 allocated to the illumination specification surface mirror 7, to illuminate the entire object field 8 in each case. The allocated illumination specification surfaces 251, 252 each include four individual mirrors ES arranged in a 2 × 2 configuration. Other N × M configurations of the individual mirrors ES are also possible, where N and M are typically in the range between 1 and 10.

[0109] The monitoring light source 43 of the monitoring device 42 is configured to generate monitoring lights 411, 412, and 413 with different wavelengths in each case. Monitoring light 411 (e.g., a medium wavelength) travels from the source position 441 of the monitoring light source 43 adjacent to the intermediate focal point 5a and is guided along the monitoring light path 311 via the satellite plane 301 and the illumination specification plane 252 to the incident point 321 on the monitoring sensor 291. The satellite plane 301 is thus assigned to the illumination specification plane 252 to be monitored.

[0110] Furthermore, monitoring light source 43 generates monitoring light 412, which has a shorter wavelength than monitoring light 411, and is guided along monitoring light channel 312 from source position 442 (again near intermediate focus 5a) to satellite subplane 302 and illumination specification subplane 251, reaching incident point 322 on monitoring sensor 292. Satellite subplane 302 is assigned to illumination specification subplane 251 to be monitored.

[0111] To further monitor the individual reflector ES3 on the illumination specification faceted reflector 7, a third monitoring light channel 313, as shown in Figure 8, is used, which begins at source position 443 (again near the intermediate focal point 5a). The monitoring light 413 originating from this third source position 443 has a wavelength greater than that of monitoring lights 411 and 412, and therefore originates from source position 44... i Departure monitoring light 41 i The three different wavelengths can be distinguished on the spectrum by the monitoring device 42.

[0112] The monitoring light channel 313 transmits light from source location 443 via the individual mirror ES3 to be monitored on the illumination specification faceted mirror 7 to another satellite facet 303 on the transmission faceted mirror 6, and then to another incident point 323 on the monitoring sensor 292. The satellite facet 303 is assigned to the individual mirror ES3 to be monitored. Unlike mirror groups ES1 and ES2, ES3 is not illuminated by light that must be imaged onto the mask master 8. This configuration is useful for measuring individual mirrors (e.g., ES3) in a targeted manner in terms of their tilt angle behavior, independent of scanner operation, since exactly one image 323 is imaged onto the sensor by that mirror. In contrast, in cases 321 and 322, in this example, four (2 × 2) images of images 211 and 212 are superimposed on the monitoring sensor 29. Therefore, the measured images 321 and 322 are averaged over the tilt angle deviations of the involved mirror groups 251 and 252.

[0113] Monitoring sensor 29 of monitoring device 42 i It can be implemented spectrally selectively, so that these monitoring sensors 291, 292 can detect light 41. i The wavelength determines which incident point 32 i Which monitoring optical channel 31 does it belong to? i In particular, the incident point 21 can be processed in parallel by the monitoring device 42. i The evaluation allows for the parallel execution of the aforementioned monitoring method-related steps, "Guiding the monitoring light 41". i Measure the target's incident point 32 i and the actual incident point 32 i "Compare with the predetermined target incident point."

[0114] By monitoring sensor 29 i The spectral selectivity or color decomposition allows for the simultaneous recording of multiple overlay images.

[0115] The monitoring light source 43 can be an RGB light source. Each of the monitoring light channels 31 has a different monitoring light wavelength. i The number can also be greater than three, and can range, for example, from three to 20 or even more. In principle, for each lighting specification to be monitored, 25 facets... i Different wavelengths of monitoring light can be used.41 i This makes even all lighting specifications facet 25 i Simultaneous detection can be achieved using monitoring sensors 29 that can distinguish different wavelengths. Alternatively, monitoring optical channels 41, each with the same wavelength, can be formed. i These monitoring optical channels belong to monitoring optical channel 31. i Monitoring optical channel 31 iThe target incident points on the monitoring sensor 29 are spatially sufficiently different, thus allowing for the use, for example, monitoring light 41 with three wavelengths and 300 illumination specification facets 25 to be monitored. i In this case, the same wavelength monitoring light 41 can be used to monitor 100 illumination specification facets respectively.

[0116] In particular, in the case of monitoring device 42, monitoring sensors 291 and 292 can be used as CMOS sensors having a color Bayer matrix suitable for monitoring the wavelength of light source 43. The Bayer matrix is ​​known, for example, from the technical article "Review of Bayer Pattern Color Filter Array (CFA) demosaicing with new quality assessment algorithms" by RA Maschal Jr. et al., ARL-TR-5061, January 2010.

[0117] Figure 9 illustrates another embodiment of the monitoring device 45 in a diagram corresponding to that of Figure 6, which can be used as a substitute for or supplement to one of the monitoring devices described above. Components and functions corresponding to those explained above with reference to Figures 1 to 8, and especially with reference to Figure 6, have the same reference numerals and will not be discussed in detail thereafter.

[0118] In the case of lighting settings intended to be monitored by monitoring device 45, the lighting specification plane 25 comprises four individual reflectors ES1 to ES4, which are combined together to form the lighting specification plane 25, such as the lighting specification plane 25 according to the embodiment of FIG8. i .

[0119] In the case of monitoring device 45, satellite facet 30 is implemented such that the actuator can be tilted by tilt angles drx and dry in a manner controlled by control device 34 via monitoring device 45, similar to what has been explained above, for example, in conjunction with the illumination specification facet 25 according to monitoring device 28 of FIG. 6. Control device 34 includes monitoring scanning unit 46, which is signal-connected to the actuator system of satellite facet 30 used by means of monitoring device 45.

[0120] As the monitoring light 3 is guided along the monitoring light channel 31, the monitoring scanning unit 46 controls the satellite facet 30 in such a way that all four individual reflectors ES1 to ES4 of the illumination specification facet 25 are scanned during the monitoring process of the illumination specification facet 25, as shown by the arrows between the individual reflectors ES1 to ES4 in Figure 9.

[0121] As the scanning process progresses, incident points 32 are assigned to the respective individual mirrors ES1 to ES4. ES1 Up to 32ES4 The two incident positions 32 are assigned to individual mirrors ES1 and ES2. ES1 and 32 ES2 This is illustrated in Figure 9. Based on these separately measured incident points 32 ESi Then, all individual reflectors ES for monitoring the lighting specification facet 25 can be used. i The monitoring method performs a comparison with the corresponding target incident point.

[0122] Figure 10 illustrates how many individual mirrors ES are available as satellite facets 30 in a typical illumination setup used in projected exposure. A plan view of the transport facet mirror 6 is shown, with those individual mirrors ES used for setting the illumination setup highlighted by the x symbol. Regarding these used individual mirrors ES, unused individual mirrors ES exist in a virtually uniform distribution across the entire surface of the transport facet mirror 6 and can be used as satellite facets 30 in the context of one of the monitoring methods described above. The number of individual mirrors ES available as satellite facets 30 is generally greater than the number of illumination specification facets 25 to be monitored, such that, in principle, the current tilt position of all illumination specification facets used for the illumination setup can be monitored by the monitoring methods described above.

[0123] Figure 11 illustrates the results of parallel measurements by way of example, for instance, using a monitoring device configured in the same manner as monitoring device 42, which can monitor a larger number of different light wavelengths 41. i The incident points 32, assigned to the monitoring light wavelengths respectively, are indicated by different symbols on monitoring sensors 291 and 292. Different light wavelengths 41 are assigned to... i The incident points 32 partially overlap each other. As described above, the spectral selectivity of the monitoring device 42 can function here.

[0124] Figure 11 shows, in plan view, the rectangular object field 8 between the sensor regions of the two monitoring sensors 291 and 292 in this case. The x-extension of the sensor regions can range between 10% and 100% of the x-extension of the object field, for example, 25% to 75%. The y-extension of the sensor regions of monitoring sensors 291, 292 is typically larger than the y-extension of the object field actually used for the current exposure, and can include, for example, the y-extension corresponding to the entire y-scan path on object field 8, or a multiple thereof; for example, 200% or 500%. This means that such magnified monitoring sensors 291, 292... i It can also be achieved at a certain distance from the object field.

[0125] Monitoring Sensor 29 i The sensor area can be implemented as a rectangle, or more specifically a square.

[0126] Figure 12, in a similar diagram to Figure 11, shows the distribution of approximately 100 incident points 32 on the sensor area of ​​one of the monitoring sensors 29 in one of the above-described embodiments of the monitoring device. This arrangement of the incident points 32 minimizes the distance between the respective predetermined target incident points of the different monitoring optical channels on the monitoring sensor 29, thus allowing these incident points 32 to be distinguished even if their actual incident points deviate from the target incident points due to the tilt of the monitored illumination specification plane 25.

[0127] Through the corresponding allocation algorithm, the satellite facet 30 can be allocated to the illumination specification facet 25 to be monitored in each case, thereby ensuring the corresponding spatial distribution of the incident points 32 and that there is a sufficient minimum distance between two adjacent target incident points.

[0128] Figures 13 and 14 illustrate another embodiment of the monitoring device 47, which can be used in place of the monitoring device described above. Components and functions corresponding to those explained above with reference to Figures 1 to 12, and particularly with reference to Figures 6 to 12, have the same reference numerals and will not be discussed in detail further.

[0129] In the case of monitoring device 47, the monitoring light source 48 is implemented as a light source grid with individual sources 49 arranged in an NxM grid. Figures 13 and 14 show the 6 × 6 grid of individual sources 49.

[0130] With the help of this light source grid, the monitoring device 47 in parallel processing enables the monitoring of the tilt position of multiple individual reflectors ES of the illumination specification facet 25, which has the same monitoring results as described above in the context of sequential scanning processing in conjunction with FIG9.

[0131] For illustrative purposes, Figures 13 and 14 show a monitoring light path from the center of the light source grid of the monitoring source 48, through the satellite facet 30 and the illumination specification facet 25 having a total of 6 × 6 individual reflectors ES, to the incident point 32 on the monitoring sensor 29. In the embodiment according to Figures 13 and 14, the illumination specification facet 25 is implemented as a 6 × 6 grid of individual reflectors ES.

[0132] Figure 13 illustrates the configuration where all individual sources 49 of the monitoring light source 48 are activated. This figure further shows the arrangement of the illumination specification plane 25 within the pupil plane of the illumination optics unit, such that a grid of corresponding source images 50 for each individual source 49 is generated on the illumination specification plane 25. The orientation of this grid of source images 50 can be determined within the context of calibration measurements. The distance between the individual sources 49 can be sized such that each source image 50 is assigned to exactly one individual mirror ES on the illumination specification plane.

[0133] When all 36 individual sources 49 are activated, in principle, under the case shown in Figure 13, all 36 individual reflectors ES of the illumination specification facet 25 to be monitored can be monitored with respect to their incident points via the monitoring light channel 31 to the sensor 29 in any case. Therefore, parallel monitoring is possible as an alternative to the scanning variant performed by means of the monitoring scanning unit 46, as shown above in conjunction with Figure 9.

[0134] To measure the individual reflector ES of the illumination specification facet 25 to be monitored, an operating configuration according to Figure 14 can be established, wherein exactly one selected individual source 49 of the monitoring light source 48 is activated, while all other 35 individual sources 49 are deactivated. The tilt angle of this assigned individual reflector ES can then be monitored via the resulting monitoring light channel 31 through the satellite facet 30 and the source image 50 at the location of the activated individual source 49.

[0135] When comparing the actual incident point with the corresponding predetermined target incident point, a known optical technique can be used as a cross-correlation technique. This cross-correlation can be used to determine the displacement of a specific incident point 32, or to determine and evaluate the relationship between the monitoring sensor 29 and multiple corresponding incident points 32. i The recorded cross-correlation signals are used to determine the displacement of multiple incident points 32 in parallel, each incident point 32 i Belongs to a monitoring optical channel 31 i .

[0136] In parallel with monitoring the illumination optical unit 11 using the aforementioned monitoring device, it is possible to perform projection exposure for imaging the mask master 12 onto the wafer 19 using a preset illumination setting.

[0137] To fabricate microstructured components, particularly highly integrated semiconductor components (e.g., memory chips), using projection exposure apparatus 1, a mask 12 and a wafer 19 are first provided. Subsequently, the structure on the mask 12 is illuminated by illumination light 3 using illumination optics 11 and projected onto a photosensitive layer on the wafer 19 using projection optics of projection exposure apparatus 1. By developing the photosensitive layer, microstructures are then formed on the wafer 19, thereby producing microstructured or nanostructured components.

[0138] The components produced can be microchips, especially memory chips.

Claims

1. An illumination optical unit (11) for projection lithography, - comprising a transmission facet mirror (6) having a plurality of transmission facets (21) for guiding illumination light (3) from an illumination source (2) along an illumination beam path through an illumination channel (27) designated by the transmission facets (21), - comprising an illumination specification facet mirror (7) having a plurality of actuator-tiltable illumination specification facets (25) for superimposing and guiding the illumination light (3) through the illumination channel (27) to a matter field (8) in which an object (12) to be illuminated can be arranged, - wherein the illumination specification facet mirror (7) is part of an optical unit, the transmission facets (21) being imaged at least into a portion of the matter field (8) via the optical unit, - comprising monitoring devices (28, 35, 42, 45, 47) having: -- At least one spatially resolved monitoring sensor (29, 291, 292), -- at least one satellite facet (30) of the transmission facet reflector (6), which in each case is assigned to exactly one of the transmission facets (21), the exact one of which then constitutes a monitoring transmission facet, and is oriented such that monitoring light (3, 41) from the monitoring light source (2, 39, 43, 48) is guided along the monitoring light channel (31) to the monitoring sensor (29, 291, 292) via the satellite facet (30) and the illumination specification facet (25) which is the illumination specification facet to be monitored, the illumination specification facet being assigned to the monitoring transmission facet via the illumination channel (27).

2. The illumination optical unit according to claim 1, characterized in that... Multiple satellite facets (30).

3. The illumination optical unit according to claim 1 or 2, characterized in that, The satellite segment (30) is adjacent to the monitoring and transmission segment (21) respectively assigned to the satellite segment (30).

4. The illumination optical unit according to any one of claims 1 to 3, characterized in that, The object field (8) has a longer field extension along a first field dimension (x) and a shorter field extension along a second field dimension (y) perpendicular to it, wherein at least one monitoring sensor (29, 291, 292) is arranged at a distance from the object field (8) along the first field dimension (x).

5. The illumination optical unit according to any one of claims 1 to 4, characterized in that, The monitoring light source (39, 43, 48) is implemented as a light source separate from the illumination light source (2), wherein the monitoring light (41) is guided along a monitoring beam path adjacent to the illumination channel (27) via at least one of the satellite facets (30) and the assigned illumination specification facet (25) to be monitored.

6. The illumination optical unit according to any one of claims 1 to 5, characterized in that, Monitoring light at multiple wavelengths (3, 41), wherein at least one monitoring sensor (291, 292) is implemented as wavelength selective.

7. The illumination optical unit according to any one of claims 1 to 6, characterized in that, Each of the transmission facets (21) is subdivided into multiple transmission individual mirrors (ES), and / or each of the illumination specification facets (25) is subdivided into multiple illumination specification individual mirrors (ES).

8. The illumination optical unit according to claim 7, characterized in that, The at least one satellite facet (30) is actuator tiltable, wherein the monitoring device (45) has a monitoring scanning unit (46) which is signal-connected to an actuator system for tilting the at least one satellite facet (30).

9. The illumination optical unit according to any one of claims 1 to 8, characterized in that, The monitoring light source (48) is implemented as a light source grid, which is implemented in a manner adapted to the individual reflectors (ES) of the illumination specification, each individual reflector forming an illumination specification facet (25).

10. A method for monitoring an illumination optical unit (11) as claimed in any one of claims 1 to 9, comprising the following steps: - Assign a satellite facet (30) to the illumination specification facet (25) to be monitored, - Guide the monitoring light (3; 41) along at least one monitoring light channel (31) via the corresponding satellite facet (30) and the assigned illumination specification facet (25) to be monitored, - Measure the actual incident point (32) of the corresponding monitoring light channel (31) on the monitoring sensor (29), - Compare the actual incident point (32) with the predetermined target incident point of the corresponding monitoring light channel (31).

11. The method according to claim 10, characterized in that, In order to allocate, the minimum distance between the predetermined target incident points of the different monitoring optical channels (31) on the monitoring sensor (29) is maintained, and / or in order to allocate, the maximum distance between the corresponding satellite segment (30) and the monitoring transmission segment (21) allocated to it is not exceeded, the monitoring transmission segment (21) being allocated to the lighting specification segment (25) to be monitored via the lighting channel (27).

12. An optical system comprising an illumination optical unit as claimed in any one of claims 1 to 9, and a projection optical unit for imaging the object field (8) onto an image field (17) in which a substrate (19) can be disposed.

13. An optical system comprising an illumination optical unit according to any one of claims 1 to 12, and comprising a monitoring light source (2, 39, 43, 48).

14. A projection exposure apparatus comprising the optical system as described in claim 12 or 13, and comprising an illumination source (2).

15. A method for manufacturing a microstructured component, comprising the following steps: - providing a mask master (12), - providing a wafer (19) having a coating sensitive to illumination light (3), - projecting at least a portion of the mask master (12) onto the wafer (19) by means of a projection exposure apparatus (1) as claimed in claim 14, - developing a photosensitive layer exposed to the illumination light (3) on the wafer (19).

16. A component produced by the method according to claim 15.

Images