WO2018134215A1

WO2018134215A1 - Imaging optical unit for guiding euv imaging light, and adjustment arrangement for such an imaging optical unit

Info

Publication number: WO2018134215A1
Application number: PCT/EP2018/051042
Authority: WO
Inventors: Rolf Freimann
Original assignee: Carl Zeiss Smt Gmbh
Priority date: 2017-01-20
Filing date: 2018-01-17
Publication date: 2018-07-26
Also published as: DE102017200935A1

Abstract

An imaging optical unit (7) serves for imaging guidance of EUV imaging light (3) from an object field (4) to an image field (8) along an imaging beam path. The imaging optical unit (7) has a plurality of mirrors (M1 to M8) that are arranged in the imaging beam path and that have reflection layers (26, 31) for the EUV imaging light (3). At least one of the reflection layers is configured as an input coupling diffraction layer (26) such that test light (21) with a test light wavelength of at least 157 nm extends along the imaging beam path after diffraction at the diffraction layer (26). Before striking the input coupling diffraction layer (26), the test light (21) extends along a test light beam path separated from the imaging light beam path. This results in an imaging optical unit in which an adjustment quality can be measured with greater precision and using a more compact structure. An adjustment arrangement (19) for such an imaging optical unit has a test light source (22a) and a test light detector (24), and also an adjustment component that is able to be influenced depending on the measurement result of the test light detector (24).

Description

Imaging optics for guiding EUV imaging light and adjustment arrangement for such imaging optics

The present patent application claims the benefit of German Patent Application DE 10 2017 200 935.7, the content of which is incorporated herein by reference.

The invention relates to an imaging optics for imaging guidance of EUV imaging light. Furthermore, the invention relates to an adjustment arrangement for such imaging optics. Furthermore, the invention relates to an optical system with an illumination optical system, such an alignment arrangement and such imaging optics, a projection exposure system with such an optical system, a method for producing a micro- or nano-structured component with such a projection exposure apparatus and a micro- or nanostructured component produced by this method.

An imaging optics of the type mentioned is known from US 2016/0085061 AI. US Pat. No. 9,372,413 B2 shows structures which have a wavelength-dependent reflective or scattering effect. US 8 228 485 B2 describes an arrangement for measuring exactly one mirror in a projection beam path. DE 10 2008 000 990 B3 shows variants of a test light coupling into an illumination and an imaging optics of a projection exposure apparatus.

It is an object of the present invention to further develop an imaging optics of the type mentioned above such that an adjustment quality of the imaging optics can be measured with high precision and a compact design. This object is achieved according to the invention by an imaging optics with the features specified in claim 1. According to the invention, it has been recognized that it is possible, without undesired impairment of the reflectivity properties of an EUV mirror, to design its reflection layer simultaneously as coupling-in diffraction layer for test light of a larger wavelength compared to EUV light. A possibly low diffraction efficiency of such a coupling diffraction layer for the test light can be accepted, since the test light can be provided with sufficient intensity. The test light can be coupled exactly along the imaging beam path. In this case, the coupling-diffraction layer is designed such that in 100% of a surface of the footprint of the imaging beam path, the test light is coupled. This can also be understood as a coupling of the test light in the diffraction-limited beam path of the imaging light.

Alternatively, a small deviation between the imaging beam path and the Prüflicht- beam path with respect to position and / or direction and / or a coupling of the test light in less than the entire surface of the footprint of the imaging beam path is possible. The coupling diffraction layer is in each case designed in such a way that the test light is coupled in at least 50% of a surface of the footprint of the imaging beam path. This lower limit for the footprint of the test light may also be greater than 50% and may be 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or at exact coupling of the test light on the imaging beam path, 100%. The test light is preferably coupled into surface portions of the footprint of the imaging beam path, which guide the test light in ways for which aberrations are to be expected. Depending on the selected coupling variant, a good control of the imaging properties as well as a test of the imaging optics for aberrations are possible due to the test light coupling.

Via an integrated test light, an adjustment quality of the imaging optics can be measured, evaluated and, if necessary, corrected. Such a test is also possible during the imaging operation of the imaging optics. The test may in particular during or after a structural integration of z. B. initially pre-aligned imaging optics in a projection exposure system. The test light beam path also extends along the imaging beam path if the two beam paths do not lie exactly on one another or run exactly in the same direction. A beam offset smaller than 100 mm and larger than 0.5 mm, larger than 1 mm, larger than 2 mm and, for example, in the range of 10 mm is possible. Also, an angular misalignment, which is smaller than 5 ° and which may be greater than 5 mrad, greater than 10 mrad, greater than 20 mrad and also greater than 50 mrad, is possible.

The diffraction layer can be applied to the respective mirror by means of a chemical or physical process. The diffraction layer can be embodied as a computer-generated hologram (CGH). A coupling-diffraction layer with lattice structure according to claim 2 has been found to be particularly suitable for the coupling of the test light. A reflection-reducing influence on the EUV imaging light can be kept low. An embodiment of the lattice structures according to claim 3 leads to a particularly small influence of the diffraction layer on the eflektivität of this diffractive layer bearing mirror with respect to the EUV imaging light. The grid structures can be designed as silicon strips. The grating structures, normal to the reflective layer to which they are applied, may have a thickness in the range between 10 and 100 nm and, for example, in the range of 20 nm.

The test light beam path can extend from a first mirror of the imaging optical system along the imaging light beam path. The Prüflicht- beam path can extend up to a penultimate or to a last mirror of the imaging optics along the imaging beam path.

The advantages of a decoupling illumination layer according to claim 4 correspond to those which have already been explained above in connection with the coupling diffraction layer. The test light can then run exactly on the imaging beam path between the coupling and the coupling-out. Separation of the test light from the EUV imaging light at the decoupling diffraction layer can be brought about by different angles of reflection of the EUV imaging light on the one hand and of the test light on the other hand.

Another object of the invention is to provide an alignment arrangement for such imaging optics. This object is achieved by an adjustment arrangement with the features specified in claim 5.

With this adjustment arrangement is directly on the test light, a measurement of effects of the along the measured imaging beam path lying mirror of the imaging optics on the Prüfflicht- wavefront possible. Since the test light extends at least in sections along the imaging beam path, the inspection of the imaging properties of the imaging optical system, which is accessible with the alignment arrangement, is very well adapted to its imaging light-conducting effect. The test light detector can be designed for wavefront measurement of the test light. In particular, a wavefront deviation, that is to say the deviation of a wavefront actual value from a predetermined wavefront nominal value, can be determined via this. With the adjustment arrangement, at least one mirror of the imaging optics can be adjusted after installation in the optics.

Alternatively or additionally, the test light detector can be designed to measure an image and / or a mirror orientation. The test light detector can be designed as a camera.

As a wavefront measurement technique, a point diffraction interferometer (PDI) may be used in the manner of that described in US 6,100,978.

At least one deformable mirror according to claim 6 leads to the possibility to bring about the adjustment arrangement an adjustment control. The deviation of a detection actual value of the test light detector from a predetermined detection setpoint value can then be used to optimize the imaging optics to a target value via the alignment arrangement. It is still possible, for example, to use a wavefront deviation or the deviation of components of the wavefront as a detection variable for the target value optimization. Alternatively, an adjustment component of the adjustment arrangement may be formed by an adjustment unit to be started manually. An adjustment component can also be realized by influencing a temperature control of at least one component of the imaging optics, for example via a cooling device. Alternatively or additionally, an adjustment component can be realized as a displacement actuator for an object to be imaged or for a substrate onto which the imaging optics are imaged. An adjustment component can also be realized via a variable vibration damping, which is influenced depending on the measurement result of the test light detector.

A coupling optics according to claim 7 may have a diaphragm. The coupling optics can have at least one coupling lens, which can be designed as a condenser. The coupling optics can have a wavefront matching unit for a test light wavefront. Such an adaptation unit can be embodied as a computer-generated hologram (CGH).

A detection optical system according to claim 8 may have a diaphragm. The detection optics can have at least one detection lens, which can be designed as a condenser. The detection optics may comprise a shear grid. The detection optics can be designed to record a shearogram. An opposite course of the beam paths according to claim 9 can be used to avoid unwanted test light striking the image field. At least one of the mirror reflection layers of the imaging optics can be embodied as a retroreflection diffraction layer in such a way that the test light which proceeds along the imaging beam path before reflection at the diffraction layer is retroreflected after the reflection at the diffraction layer and again longitudinally of the imaging beam path runs. In this case, a decoupling diffraction layer on one of the mirrors of the imaging optics can also be used to decouple the test light. A detection of the alignment arrangement can be separated from a test light source via a partially transparent mirror.

The diffraction layer, which is used for coupling and / or decoupling and / or retroreflection of the test light, can be embodied as a computer-generated hologram (CGH). The advantages of a retroreflector according to claim 10 correspond to those which have been explained above in connection with the retroreflection diffraction layer. The retroreflector can be designed as a plane mirror, as a spherical mirror or as an aspheric mirror. The retroreflector can be designed as a freeform surface mirror.

When using a retroreflection, a Fizeau interferometer can also be arranged for detection on the coupling-in side of the adjustment arrangement. The retroreflector may be preceded by a wavefront matching unit. This adjustment unit can be operated in a double pass. The adaptation unit can be designed as a computer-generated hologram (CGH). The advantages of an adjustment arrangement according to claim 1 1 correspond to those which have already been explained above in connection with the imaging optics on the one hand and the adjustment arrangement on the other hand. The advantages of an optical system according to claim 12, a projection exposure apparatus according to claim 13, a manufacturing method according to claim 14 and a micro- or nano-structured component according to claim 15 correspond to those already explained above with reference to the imaging optics on the one hand and the adjustment arrangement on the other hand were. The optical system according to claim 12 can be an assembly for a scanner-type projection exposure apparatus, in particular of the "EUV scanner" type, which can be an anemophotographic optical unit of the optical system, ie part of the illumination optics and / or the imaging optics Corresponding anamorphic optical units are described in WO 2016/012 426 A1, WO 2016/012 425 A2, US 2013/0128251 A1, US Pat

US 2016/0327868 AI, DE 10 2014 208 770 AI and WO 2016/078 819 AI. Embodiments of the invention will be explained in more detail with reference to the drawing. In this show:

1 shows schematically a projection exposure apparatus for EUV microlithography;

Fig. 2 in a meridional section an embodiment of an imaging

Optics, which is used as a projection lens in the projection exposure apparatus according to FIG. 1, wherein an EUV imaging beam is used for a main beam and for a top beam and a bottom beam. In addition to the imaging optics, components of an adjustment arrangement for the imaging optics, including a test light source and a test light detector, are additionally shown, wherein additionally where a test light beam path from the Abbildungslicht-

Diffracted beam path, the Prüfflicht beam path is shown in dashed lines;

FIG. 3 schematically shows a section through one of the mirrors of the imaging optical system according to FIG. 2, which carries an eflection layer which is embodied as a single-point diffraction layer for the test light, again in the region of a reflection or diffraction at the coupling diffraction layer on the one hand the imaging beam path and on the other hand the test light beam path are shown;

4 shows an enlarged detail of the detail IV in FIG. 3, which shows a layer structure of the coupling diffraction layer including grating structures applied there; FIG. FIG. 5 shows details of a coupling-in optical system of the alignment arrangement between the test light source and the coupling-in diffraction layer; FIG.

Details of a detection optics of the alignment arrangement in Prüflicht- beam path after passing through components of the imaging optics;

FIGS. 7 and 8 each show further embodiments of the adjustment arrangement in a representation similar to FIG. 2; and 9 shows details of an eflexion unit as part of the embodiment of the adjustment arrangement according to FIG. 8, including a retroreflector.

A projection exposure apparatus 1 for microlithography has a light source 2 for illumination light or imaging light 3. The light source 2 is an EUV light source, the light in a wavelength range, for example between 5 nm and 30 nm, in particular between 5 nm and 15 nm , generated. The light source 2 may in particular be a light source with a wavelength of 13.5 nm or a light source with a wavelength of 6.9 nm. Other EUV wavelengths are possible. The light source 2 can be an EUV light source of the type "plasma discharge by gas discharge (Gasdischarge produced Plasma, GDP)", the type "laser-induced plasma generation (LPP)" or a synchrotron-based EUV light source, For example, to a free-electron laser (FEL) act. A beam path of the illumination light 3 is shown extremely schematically in FIG.

For guiding the illumination light 3 from the light source 2 to an object field 4 in an object plane 5 is an illumination optical system 6. With a projection optics or imaging optics 7, the object field 4 is imaged in an image field 8 in an image plane 9 with a predetermined reduction scale. To facilitate the description of the projection exposure apparatus 1 and the various embodiments of the projection optics 7, a Cartesian xyz coordinate system is indicated in the drawing, from which the respective positional relationship of the components shown in the figures results. In FIG. 1, the x-direction is perpendicular to the drawing level into it. The y-direction runs to the left and the z-direction to the top.

The object field 4 and the image field 8 are rectangular. Alternatively, it is also possible for the object field 4 and the image field 8 to be bent or curved, that is to say in particular to be part-ring-shaped. The object field 4 and the image field 8 have an xy aspect ratio greater than 1. The object field 4 thus has a longer object field dimension in the x direction and a shorter object field dimension in the y direction. These object field dimensions run along the field coordinates x and y.

For the projection optics 7, one of the exemplary embodiments illustrated in FIGS. 2 et seq. May be used. The projection optics 7 according to FIG. 2 are reduced by a factor of 8. Other reduction scales are also possible, for example 4x, 5x or even reduction scales which are larger than 8x. The image plane 9 is arranged in the projection optics 7 in the embodiments of FIGS. 2 and 5 ff. Parallel to the object plane 5. An object in the form of a section of a reflection mask 10 that coincides with the object field 4 is shown, which is also referred to as a reticle. The reticle 10 is supported by a reticle holder 10a. The reticle holder 10a is displaced by a reticle displacement drive 10b.

The imaging through the projection optics 7 takes place on the surface of a substrate 1 1 in the form of a wafer, which is supported by a substrate holder 12. The substrate holder 12 is displaced by a wafer or substrate displacement drive 12a. FIG. 1 schematically shows a bundle of rays 13 of the illumination light 3 entering into the latter and the projection optics 7 and between the projection optics 7 and the substrate 11 a beam bundle 14 of the illumination light 3 emerging from the projection optics 7. An image field-side numerical aperture (NA) of the projection optics 7 is not reproduced to scale in FIG.

The projection exposure apparatus 1 is of the scanner type. Both the reticle 10 and the substrate 11 are scanned in the y direction during operation of the projection exposure apparatus 1. A stepper type of the projection exposure apparatus 1, in which a stepwise displacement of the reticle 10 and of the substrate 11 in the y-direction between individual exposures of the substrate 11, is possible. These displacements are synchronized with each other by appropriate control of the displacement drives 10b and 12a.

FIG. 2 shows the optical design of a first embodiment of the projection optics 7. Shown in FIG. 2 is an imaging beam path of the imaging light 3 using the example of three individual beams 15 emanating from a central object field point. Shown are a main beam 16, ie a single beam 15, which passes through the center of a pupil in a pupil plane of the projection optics 7, as well as an upper and a lower coma beam of this object field point. Starting from the object field 4, the main ray 16 closes with a normal to the object plane 5 an angle of z. B. 5.5 °.

The imaging beam path of the imaging light 3 is a channel predetermined by the optical design of the projection optics 7 between the object field 4 and the image field 8, via which the guide of the imaging light 3 and thus the imaging of structures on the reticle 10 within predetermined aberration tolerances is possible. The imaging beam path is independent of whether the imaging light 3 actually propagates everywhere. The imaging beam path depends exclusively on the design of the reflection surfaces of the mirrors M1 to M8 of the projection optics 7 and possibly on edge contours of an aperture diaphragm and / or an obscuration diaphragm of the projection optics 7.

A cross-sectional area of the imaging beam path on one of the reflection surfaces of the mirrors M1 to M10 on the one hand and a cross-sectional area of the imaging beam path between these mirrors perpendicular to the respective course of the main beam 16 on the other hand is also referred to as a footprint. Details of the projection optics 7 are known from US 2016/0085061 A1 (cf the local Fig. 12).

The eight mirrors of the imaging optics 7 are numbered in the order of their exposure to the imaging light 3 of Ml to M8 (Mi, i = 1 to 8), which are shown schematically as a plane mirror, but in fact each having a curved mirror surface. The mirrors M1 to M8 carry reflective layers for the EUV imaging light. The last in the imaging beam path mirror M8 has a passage opening 17 for the passage of the imaging light 3, which runs between the mirrors M6 and M7, on.

At least one of the mirrors M1 to M8 can be designed as a deformable mirror, which is explained using the example of the mirror M7. The deformable mirror M7 includes a deformation actuator 18, which is included with at least a portion of the mirror M7 is in mechanical operative connection, which is indicated in Fig. 2 by dotted lines. For example, defined pressure can be exerted on one or more sections of a mirror surface of the mirror M7 via the deformation actuator 18, which leads to a corresponding, defined deformation of this mirror surface. Alternatively or additionally, the mirror surface can be embodied, at least in sections, as a displaceable and / or tiltable mirror section, for example in the form of a mirror facet. Deformation actuator 18 is part of an alignment arrangement 19 for adjusting the imaging beam path of imaging optics 7.

Depending on the design of the alignment arrangement 19, several of the mirrors Mi of the imaging optics 7 may also be equipped with at least one such deformation actuator 18. By way of example, a corresponding deformation actuator 18 is also indicated in the mirror M8, which acts on different sections of the mirror M8, between which the passage opening 17 is located. The mirror M8 may be equipped with a plurality of such deformation actuators 18.

The alignment arrangement 19 includes a transmission unit 20 for test light 21, again part of the transmission unit 20 being a test light source 22a. The test light 21 has a test light wavelength that is at least 157 nm. The test light 21 is therefore light with a wavelength that is greater than an EUV wavelength. The test light 21 may have a DUV (Deep Ultra Violet), UV, VIS (Visually) or even an IR (Infrared) wavelength, or a combination of these wavelengths. 2 again shows, by way of example, three individual beams 22 of the test light 21, which are assigned to the main beam 16 of the imaging light 3 and to the lower and upper coma beams of the imaging light 3, that is to say one of the three individual beams 15 shown.

For alignment arrangement 19 further includes a test light receiving unit 23 with at least one test light detector 24 for detecting the test light 21, which has either passed through the entire imaging beam path through the imaging optical system 7 or at least a portion of this imaging beam path. The test light detector 24 may be a camera and / or a CCD or CMOS detector.

The latter is in a signal connection with the transmitting unit 20, in particular with the test light source 22a, with the receiving unit 23, in particular with the test light detector 24, and with the at least one deformation actuator 18 Furthermore, the control / regulation unit 25 can also be in signal communication with the reticle displacement drive 1 Ob and / or with the wafer displacement drive 12 a, which can then likewise belong to the adjustment arrangement 19.

With the test light detector 24, a wavefront of the test light 21 can be measured. Alternatively or additionally, it is possible to carry out with the test light detector 24 a measurement of mirror layers of the mirrors M1 to M8 or mirror orientations of the mirrors M1 to M8.

3 and 4 show details of a reflection layer 26 of a mirror surface of the mirror M1 of the imaging optical system 7, which on the one hand is used as reflection layer for the EUV imaging light 3 and, on the other hand, as a coupling diffraction layer for the test light 21. The shape of a substrate 27 of the mirror Ml is shown only schematically in FIG.

The reflection layer 26 initially has a plurality of individual layers 28 which form a highly reflective layer 29, namely a highly reflective multilayer, for the EUV imaging light 3. This multilayer may be constructed, for example, with a plurality of bilayers alternately made of molybdenum and silicon. Alternatively, and in particular where the EUV imaging light 3 is deflected grazing by the mirrors Mi of the imaging optics 7, a construction with at least one highly reflective layer for the EUV imaging light 3, for example with at least one ruthenium layer, can also be used ,

Applied as a diffraction layer on this reflective layer 29 by a physical or chemical coating method is a plurality of reflective grating structures 30 arranged regularly on the reflective layer 29. These grating structures 30 may be silicon pads or silicon strips. The grating structures 30 may have a thickness in the range between 10 nm and 100 nm, for example a thickness in the region of 20 nm, normal to the layer 29. Individual structures in the form of platelets or pads which can be used to construct such grating structures 30 are known from US Pat. No. 9,372,413 B2. Due to the low strength of the grating structures 30 whose diffraction efficiency for the test light 21 is comparatively low, but this can be tolerated. In the layer plane of the coupling diffraction layer 26, the grating structures 30 have an extent and / or a distance from one another such that the grating structures 30 qualitatively satisfy a diffraction equation of the form: d (sin α + sin β) = mk. Here, d is the period of the grating structures 30. α is an angle of incidence of the inspection light 21 on the coupling diffraction layer 26 (see Fig. 3). β is a failure angle of the inspection light 21 after diffraction at the one-electron diffraction layer 26 which is the same as the failure angle of the reflected EUV imaging light 3. m is the diffraction order of the inspection light 21 and is for example +/- 1 or +/- 2. A higher diffraction order is also possible, λ is the wavelength of the test light 21. The grating period d is adjusted by specifying the extent and / or the distance of the grating structures 30 in the layer plane of the coupling diffraction layer 26 such that at a given angle of incidence α of the test light 21 on the coupling-diffraction layer 26 of the diffraction-Ausfallwinkel ß of the test light 21 is the same as a reflection-Ausfallwinkel ß of the EUV imaging light. 3

After the test light 21 has been coupled into the imaging beam path at the coupling diffraction layer 26, the test light 21 runs along the imaging beam path through the imaging optical system 7 until it reflects on the penultimate mirror M7. A reflection layer 31 of the mirror M7 is designed as a coupling-out diffraction layer whose function is clear from the reverse beam path at the reflection layer 26 according to FIG. The decoupling diffraction layer 31 of the mirror M7 in turn has grating structures corresponding to the grating structures 30 in such a way in that the test light 21, which runs along the imaging beam path before the reflection at the coupling-out diffraction layer 31, after the reflection at the coupling-out diffraction layer 31 (angle of incidence β) runs along a test light beam path to the receiving unit 23, which differs from the imaging - Beam path of the EUV imaging light 3 is separated (failure or reflection angle ß for the reflected EUV imaging light 3 and α for the diffracted test light 21).

The coupling diffraction layer 26 is embodied such that the test light 21 is coupled in at least 50% of a surface of the footprint of the imaging beam path. At least half of a cross-sectional area of the imaging beam path is therefore acted on along the course of the test light 21 in the projection optics 7 with the test light 21. In the embodiment of the test light coupling shown in FIG. 2, the test light 21 is actually coupled into the entire surface of the footprint of the imaging beam path. Depending on the design of the test light coupling, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90% or at least 95% of the surface of the footprint of the imaging beam path, the test light 21 are coupled.

Insofar as, unlike in the embodiment shown in FIG. 2, the test light 21 is coupled in less than 100% of the surface of the footprint of the imaging beam path, this test light coupling can be designed such that the test light 21 is preferably in the range of outer circumference is coupled to the surface of the footprint of the imaging beam path. For example, if the test light is coupled in 50% of the area of the footprint of the imaging beam path, this input coupling in the manner of a circumferential ring within the surface of the footprint of the imaging beam path.

FIG. 5 shows details of the transmission unit 20. After the test light source 22a, first a test light diaphragm 32 is arranged. As far as a sine grid is used in the receiving unit 23, the test light aperture 32 may be designed as a pinhole. As far as a rectilinear grid is used in the receiving unit 23, the Prüfflicht aperture 32 as

Checkerboard be executed.

In the test light beam path after the test light aperture 32, the transmission unit 20 includes a condenser 33, for example in the form of a condenser lens, and subsequently an optical matching unit 34 for a test light wavefront 35 for adaptation to the imaging light wavefront in the region of the coupling of the Test light 21 in the imaging beam path. The adjustment unit 34 may be a computer-generated hologram (CGH). The components 32 to 34 represent a coupling-in optics of the adjustment arrangement 19. FIG. 6 shows details of the receiving unit 23 of the adjustment arrangement 19. The receiving unit 23 will be explained using the example of recording a test-light sherogram. The coupled-out projection light wavefront 35 first passes through a condenser 36 of the receiving unit 23, which in turn may be a condenser lens, and subsequently a grating arrangement 37 of the receiving unit 23. The components 36 and 37 represent detection optics of the adjustment arrangement 19. The grid arrangement may be a sine grid or a linear grid. The grid assembly 37 is arranged downstream of the Test light detector 24 in the form of a camera for recording the score.

The alignment arrangement 19 is used as follows:

To adjust the imaging optics 7, the test light 21 is coupled via the coupling-diffraction layer 26 into the imaging beam path of the imaging optics 7. The test light 21 then runs along the imaging beam path, starting from the reflection at the mirror Ml to the reflection at the mirror M7 and is coupled out there again at the coupling-out diffraction layer 31 from the imaging beam path. An influence on the test light wavefront 35 via the reflections on the mirrors M1 to M7 is then evaluated with the aid of the receiving unit 23.

This evaluation supplies information, for example, about an actual mirror position of at least one of the mirrors Ml to M7 deviating from a target mirror position, that is, for example, information about a mirror displacement and / or about a mirror deformation. This information is evaluated in the control unit 25. By outputting corresponding actuating signals, for example at the at least one deformation actuator 18, a difference between the measured actual test light wavefront 35 and a predetermined desired test light wavefront 35 can then be minimized.

Alternatively or additionally, the information obtained can be used to refine a temperature model of the imaging optics 7, which can be used, for example, for the corresponding design and / or actuation of a cooling device for at least one of the mirrors of the imaging optics. the optics 7 can be used. Such a cooling device 38 is shown schematically in FIG. 2 at the mirror M4. It may be an active and / or a passive cooling device. Can be cooled with a gaseous or liquid cooling medium, which can be performed in a cooling circuit. The cooling device 38 may include at least one heat exchanger.

Again alternatively or additionally, the test light information obtained via the adjustment arrangement 19 can be used to refine a vibration model with regard to a mounting of the optical components of the imaging optical unit 7. With this information, an optimization of the holding arrangements for these optical components can then be made, for example, a targeted vibration damping. The alignment arrangement 19 can be used, in particular, in a production of the projection exposure apparatus 1 if the imaging optic 7 is integrated as an assembly in the projection exposure apparatus 1. The imaging optics is regularly pre-adjusted prior to such integration. With the aid of the adjustment arrangement 19, this adjustment can then be checked after integration and, if necessary, corrected.

With the adjustment arrangement 19, monitoring of the adjustment of the optical components of the imaging optical system 7 in the projection mode of the projection exposure apparatus 1 is possible.

Alternatively or additionally, the information obtained via the test light 21 in the receiver unit 23, in particular the wavefront measurement results, can be used to conclude an exact position, ie a position and / or orientation, of the image field 8 in the room. This can be used to bring about an image position correction by appropriate control of displacement actuators of the substrate holder 12. A further embodiment of an adjustment arrangement 39 will be described below with reference to FIG. 7, which is used instead of the adjustment arrangement 19 according to FIG. 2. Components and functions corresponding to those already explained above with reference to FIGS. 1 to 6 bear the same reference numerals and will not be discussed again in detail.

In the case of the alignment arrangement 39, a course direction of the test light 21 along the imaging beam path is exactly opposite a direction of the EUV imaging light 3. The test light 21 is then coupled in via the reflection layer 31 on the mirror M7 in accordance with what has been mentioned above in connection with the reflection layer 26 of the mirror Ml has been explained in the alignment arrangement 19, and via the reflection layer 26 of the mirror Ml in the alignment arrangement 39, a coupling of the test light 21, again corresponding to what above in connection with the reflective layer 31 of the mirror M7 in the alignment arrangement 19 was explained. The coupling-in and coupling-out layers thus exchange their roles in the comparison between the alignment arrangements 19, 39 of FIGS. 2 and 7. Accordingly, in the adjustment arrangement 39, the transmitting unit 20 adjacent to the mirror M7 and the receiving unit 23 adjacent to the mirror Ml arranged. A further embodiment of an adjustment arrangement 40 will be described below with reference to FIG. 8, which is used instead of the adjustment arrangement 19 according to FIG. 2. Components and functions corresponding to those already explained above with reference to FIGS. 1 to 7 bear the same reference numerals and will not be discussed again in detail.

Instead of the transmitting unit 20 of the adjusting arrangement 19, an interferometer unit 41 occurs in the case of the adjusting arrangement 40. Instead of the receiving unit 23 of the adjusting arrangement 19, a reflection unit 42 occurs in the case of the adjusting arrangement 40.

9 shows details of the reflection unit 42. The test light wavefront 35 in turn passes through a wavefront arrangement unit 43 in the form of a computer-generated hologram. Subsequently, the test light 21 is reflected back at a retroreflector 44. The retroreflector 44 may be a mirror that may be planar, spherical, or aspherical. The mirror 44 can also have a reflection surface in the form of a free-form surface. The free-form surface can be formally described, as described, for example, in US 2016/0085061 A1 and the references cited therein.

After retroreflection at the retroreflector 44, the test light 21 in turn passes through the wavefront matching unit 43 and then enters the imaging beam path of the imaging optical system 7 via the reflection layer 31, which simultaneously serves as decoupling and coupling-in layer. In the case of the alignment arrangement 40, the inspection light 21 passes through the imaging beam path of the imaging optical system 7 between the mirrors M1 and M7, ie in the double pass. After this double pass and successful decoupling of the test light 21 on the mirror Ml the decoupled test light 21 in the interferometer unit 41, which can be designed as a Fizeau interferometer, measured. The interferometer unit 41 thus has both the function of the transmitting unit 20 and that of the receiving unit 23, as described above in connection with the adjusting arrangements 19 and 39. The test light beam path runs approximately exactly along the imaging beam path.

As far as the test light beam path is concerned, the receiving unit in the alignment arrangement 40 can be separated from the transmitting unit, for example via a partially transparent mirror. As an alternative to the interferometer unit 41, therefore, both the transmitting unit 20 and the receiving unit 23 can be arranged in their place in the alignment arrangement 40, wherein both units 20 and 23 share a beam path and a coupling or decoupling in only by the transmitting unit 20 or only partial beam paths used by the receiving unit 23 can be made via corresponding mirrors which are partially transparent to the test light 21.

To produce a micro- or nano-structured component, the projection exposure apparatus 1 is used as follows: First, the reflection mask 10 or the reticle and the substrate or the wafer 11 are provided. Subsequently, a structure on the reticle 10 is projected onto a photosensitive layer of the wafer 1 1 with the aid of the projection exposure apparatus 1. By developing the light-sensitive Layer is then a micro or Nanostmktur on the wafer 1 1 and thus generates the microstructured component.

In the projection exposure, as explained above, the adjustment arrangement can be used in one of the embodiments described.

Claims

claims

1. Imaging optics (7) for imaging guidance of EUV imaging light (3) from an object field (4) to an image field (8) along an imaging beam path,

having a plurality of mirrors (M1 to M8) arranged in the imaging beam path and carrying reflection layers (26, 31) for the EUV imaging light (3),

wherein at least one of the reflection layers as Einkoppel- diffraction layer (26) is designed so that test light (21) of a

Test light wavelength which is at least 157 nm, which before incidence on the coupling diffraction layer (26) along a Prüflicht- optical path, which is separated from the imaging beam path, after diffraction at the diffraction layer (26) along the imaging beam path runs,

wherein the coupling diffraction layer (26) is designed such that in at least 50% of a surface of a footprint of the imaging beam path, the test light (21) is coupled. 2. Imaging optics according to claim 1, characterized in that the coupling-diffraction layer (26) has a plurality of regularly on a reflective layer (29) arranged reflective grating structures (30) which have an extent and / or a distance from each other such, that a grid diffraction equation is sufficient, so that at a given angle of incidence (a) of the

Test light (21) on the coupling diffraction layer (26) of the diffraction angle (ß) of the test light (21) is the same size as a reflection onsidence angle of the EUV imaging light (3). Imaging optics according to claim 2, characterized in that the grating structures (30) are designed as silicon pads.

Imaging optics according to one of claims 1 to 3, characterized in that at least one of the reflection layers as outcoupling diffraction layer (31) is designed so that the test light (21), which before the reflection at the decoupling diffraction layer (31) along the After the reflection at the outcoupling diffraction layer (31) along an examination light beam path, which is separated from the imaging beam path, the imaging beam path runs.

Adjusting arrangement (19, 39, 40) for an imaging lens according to one of Claims 1 to 4

with a test light source (22a) for generating the test light (21), with a test light detector (24) for detecting the test light (21), which has passed through at least a portion of the imaging beam path,

with an adjustment component, which can be influenced depending on the measurement result of the test light detector (24).

Adjusting arrangement according to claim 5, characterized by at least one deformable mirror (M7) of the imaging optical system (7) with at least one deformation actuator (18) which is in signal connection with the test light detector (24) via a control / regulating unit (25).

Adjustment arrangement according to claim 5 or 6, characterized by a coupling-in optics (32, 33, 34) in a test light beam path after the test light source (22a). Adjustment arrangement according to one of Claims 5 to 7, characterized by detection optics (36, 37) in the test light beam path in front of the test light detector (24).

Adjustment arrangement according to one of claims 5 to 8, characterized by an embodiment such that when running with the imaging optics assembly as a direction of the test light (21) along the imaging beam path exactly opposite a direction of the EUV imaging light (3).

10. Adjustment arrangement according to one of claims 5 to 9, characterized by at least one etroreflektor (44) which is designed so that the test light (21) passes through at least a portion of the imaging beam in the double pass.

1 1. Adjusting arrangement according to one of claims 5 to 10, characterized by an imaging optical system according to one of claims 1 to 4.

12. An optical system with an illumination optical system (6) for illuminating an object field (4) and an alignment arrangement according to one of claims 5 to 1 1 and an imaging optics for imaging the object field (4) in an image field (8).

, A projection exposure apparatus comprising an optical system according to claim 12 and an EUV light source (2).

14. Method for producing a structured component with the following method steps: Providing a reticle (10) and a wafer (11),

Projecting a structure on the reticle (10) onto a photosensitive layer of the wafer (1 1) using the projection exposure apparatus according to claim 13,

- Creating a micro or nanostructure on the wafer (1 1).

15. Structured component, produced by a method according to claim 14.