Method for reworking an optical element, as well as optical element and optical system

Abstract

The invention relates to a method for reworking an optical element, in particular for microlithography, wherein the optical element has a first functional layer (203) which may be located on a substrate or existing support layer (202) that has been customized for use in a first optical system by means of a matching layer system (204), wherein the method comprises the following steps: coating the first functional layer (203) with a matching layer system (204), applying a support layer (205) to the matching layer system (204), determining a wavefront effect desired for reuse of the optical element, and performing a layer manipulation depending on the desired wavefront effect and, if desired, applying a second functional layer (206).

Description

BACKGROUND OF THE INVENTIONField of the invention

[0001] The invention relates to a method for reworking an optical element, as well as an optical element and an optical system, in particular for microlithography. State of the art

[0002] Microlithography is used to manufacture microstructured components, such as integrated circuits or LCDs. The microlithography process is carried out in a so-called projection exposure system, which has an illumination device and a projection lens. The image of a mask (= reticle) illuminated by the illumination device is projected by the projection lens onto a substrate (e.g., a silicon wafer) coated with a light-sensitive layer (photoresist) and arranged in the image plane of the projection lens, in order to transfer the mask structure to the light-sensitive coating of the substrate.

[0003] Mask inspection systems are used to inspect reticles for microlithographic projection exposure systems.

[0004] In projection lenses or inspection lenses designed for the EUV range, ie at wavelengths of e.g. about 13.5 nm or about 6.7 nm, reflective optical elements are used as optical components for the imaging process due to the lack of availability of suitable light-transmitting refractive materials.

[0005] In the course of the development of projection lenses with ever higher resolution and the associated increasing accuracy requirements, the implementation of the respective adjustment process, in the course of which the respective optical system is "brought into specification" using the available degrees of freedom or manipulators, represents an increasingly demanding challenge. In the sense of the present invention, "adjustment" is understood to mean the iterative reduction of the optical effects of process errors that accompany the manufacturing process of the optical system or the associated optical elements (e.g. grinding errors on lenses, screwing effects on optical elements or their mounts, etc.).

[0006] A problem that occurs in practice is the failure of optical elements (e.g. lenses or mirrors), especially after the adjustment described above has already been carried out and after they have already been used in an optical system.

[0007] For this purpose, it is fundamentally conceivable to remove the optical element to be repaired or reworked from the respective optical system and then first to "de-coat" it (i.e. to remove a typically existing functional layer such as AR coating), in order to then first carry out a pass machining for the purpose of re-individualizing the optical element and thus adapting it for renewed use, whereupon a new functional layer is applied and the optical element can be installed either in the existing optical system or in a different (i.e. a new or one to be repaired) optical system.

[0008] However, this procedure is either associated with a comparatively high level of effort, particularly with regard to decoating, or - and this applies to many optical elements in use, especially in microlithography - there are no suitable and reproducible decoating processes available, so that the method outlined above could not be used at all.

[0009] Therefore, in practice, a certain level of stockpiling of replacement elements or complete systems is required for optical elements in microlithography that are fundamentally at risk of failure, because immediate re-production only at the moment of a sudden failure caused by an accident would lead to intolerable downtimes of the systems in the field and the resulting semiconductor production losses due to the complex manufacturing processes - often with the necessary additional integration of microelectronic and micromechanical components into the optical elements.

[0010] Such storage of optical elements or complete optical systems is associated with considerable financial and logistical expenditure in view of the complexity and value of the optical elements or systems used in microlithography and the increasing diversification of the elements, whereby the stock availability of an optical element that may be required due to an accident cannot always be guaranteed under unfavorable conditions (e.g. several failures of the same element at the same time).

[0011] Furthermore, the production of optical systems for microlithography - partly due to the complex, high-precision processing methods - is associated with a high use of resources and thus a considerable CO2 footprint.

[0012] The possibility of reprocessing optical elements that were previously in use and that are to be customized to the “new” optical system by means of pass-processing would therefore be extremely advantageous both economically and ecologically, also with regard to a possible reduction in the storage of replacement elements that may never be needed.

[0013] For the prior art, reference is made solely to DE 10 2021 201 193 A1, US 7,170,915 B2, US 7,629,572 B2, US 4,533,449, EP 3 286 595 B1 and WO 2017 / 125362 A1. SUMMARY OF THE INVENTION

[0014] It is an object of the present invention to provide a method for reworking an optical element, as well as an optical element and an optical system, in particular for microlithography, which enable a reworking that is as time-saving, resource-saving and reliable as possible while at least partially avoiding the problems described above.

[0015] This problem is solved according to the features of the independent patent claims.

[0016] According to one aspect, the invention relates to a method for reworking an optical element, in particular for microlithography, wherein the optical element has a first functional layer, the method comprising the following steps: a) Overcoating the first functional layer with an adaptation layer system; b) applying a carrier layer to the matching layer system; c) determining a wavefront effect desired for reuse of the optical element; and d) optionally performing a layer manipulation on the optical element depending on the desired wavefront effect.

[0017] The present invention is based in particular on the concept of reworking an optical element which has a functional layer (possibly on an already existing, individualized pass or an individualized (existing) carrier layer) and has typically already been individualized for use in an optical system by pass processing, in such a way that no decoating (i.e. removal of the existing functional layer) is carried out, but rather an adaptation layer system with a new or additional carrier layer is applied to the existing functional layer by means of an "overcoating".

[0018] Depending on the requirements of the optical element, it is also conceivable that layer manipulation can be dispensed with in certain cases; in particular, if the desired wavefront effect is already achieved without such layer manipulation.

[0019] Against this background, step d) above is described as optional, although it will be appropriate in the vast majority of cases.

[0020] According to the invention, the individualization or fitting processing required for the renewed use of the optical element in question in an optical system is then preferably carried out on this "new" carrier layer, if necessary, after which an additional new functional layer (e.g. anti-reflective coating) is applied if necessary.

[0021] In addition to the aforementioned layers or layer systems, technically appropriate or necessary intermediate layers, such as adhesion-promoting layers, may be provided if necessary. Such intermediate layers are possible, for example, between the first functional layer and the matching layer system, between individual or multiple layers of the matching layer system, or between the matching layer system and the carrier layer or on the carrier layer.

[0022] By applying the matching layer system to the remaining first functional layer in conjunction with the carrier layer applied thereon, which can then be subjected to individualizing layer manipulation, the required optical properties, in particular with regard to the anti-reflective effect, can be ensured despite the omission of decoating.

[0023] According to one embodiment, the method further comprises the step: e) Applying a second functional layer to the carrier layer.

[0024] The second functional layer can in particular be an AR (anti-reflective) layer.

[0025] According to one embodiment, a layer design of the second functional layer is designed taking into account the existing first functional layer. In particular, the layer design of the second functional layer can be configured such that, through the interaction of the first and second functional layers, a predetermined specification requirement is met by the optical element or the corresponding optical system in which the optical element is to be used after reworking, for example, with regard to the anti-reflective effect.

[0026] From a wave-mechanical perspective, the matching layer system is preferably designed such that the complex conductance (admittance) of the first (i.e., not removed) functional layer is adapted to the complex conductance of the carrier layer.

[0027] The matching layer system is preferably formed from a sequence of optical layers of predetermined layer thickness with varying refractive index.

[0028] According to one embodiment, step c) of determining the desired wavefront effect comprises determining a system wavefront deviation between an existing system wavefront and a desired system wavefront for an optical target system. In this case, the "adjustment concept" described in the introduction is implemented in the sense of individualizing the optical element to match the desired system wavefront of the associated optical target system.

[0029] According to one embodiment, the layer manipulation of the carrier layer is selected depending on the desired wavefront effect using a previously determined lookup table in which the respective wavefront effect of the optical element is listed for different layer manipulations of the carrier layer.

[0030] According to one embodiment, the layer manipulation takes place on the adaptation layer system and / or the carrier layer and / or on a possibly provided new, second functional layer.

[0031] However, the layer manipulation is particularly preferably performed on the carrier layer (new and preferably designed for layer manipulation in terms of its thickness), since in this case the performance of the matching layer system is not impaired. Nevertheless, it would be conceivable for a layer manipulation step—such as ion implantation—to also gradually extend into the area of ​​the matching layer system. Furthermore, it would be conceivable to subject an optionally applied new, second functional layer to layer manipulation alternatively or additionally.

[0032] According to one embodiment, the layer manipulation comprises performing a locally varying layer removal.

[0033] In the case of layer manipulation on the carrier layer, the layer thickness of the carrier layer can preferably correspond at least to the expected maximum layer removal during the layer manipulation.

[0034] According to one embodiment, the layer manipulation comprises performing a locally varying deposition of a layer material.

[0035] According to one embodiment, the layer manipulation comprises performing a locally varying ion implantation.

[0036] According to one embodiment, the carrier layer comprises silicon dioxide (SiO2) - this is a preferred material for lenses - or silicon (Si) - this is a preferred material for mirrors.

[0037] According to one embodiment, the layer manipulation is further carried out in such a way that one or more optical properties of the optical element from the following group of optical properties are maintained or optimized at the original level with only the first functional layer: - Polarization effect in terms of reflection splitting and / or phase splitting, and / or - reflexive effect, and / or - Transmission effect.

[0038] According to one embodiment, the optical element is a lens.

[0039] According to one embodiment, the optical element is a mirror.

[0040] In further embodiments, the optical element can also be a wavefront correction element, as is known, for example, from DE 10 2017 206 256 A1.

[0041] According to one embodiment, the optical element is designed for an operating wavelength of less than 250 nm, in particular less than 200 nm.

[0042] According to a further embodiment, the optical element is designed for an operating wavelength of less than 30 nm, in particular less than 15 nm.

[0043] According to one embodiment, the optical system is a projection lens of a microlithographic projection exposure system.

[0044] According to a further embodiment, the optical system is a projection lens of a mask inspection system.

[0045] According to a further embodiment, the optical system may be an illuminator for a microlithography projection exposure system, or another optical component of such a system.

[0046] The invention further relates to an optical element, in particular for microlithography, which is formed by carrying out a method with the features described above, as well as to an optical system with such an optical element.

[0047] Further embodiments of the invention can be found in the description and the dependent claims.

[0048] The invention is explained in more detail below with reference to embodiments shown in the attached figures. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] They show: Fig. 1 a flowchart to explain the possible sequence of a method according to the invention for reworking an optical element; Fig. 2a-2d are schematic representations illustrating the possible sequence of a method according to the invention for reworking an optical element; Fig. 3 a schematic representation of the possible structure of a microlithographic projection exposure system designed for operation in DUV; and Fig. 4 a schematic representation of the possible structure of a microlithographic projection exposure system designed for operation in the EUV. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0050] Fig.1 shows a flow chart to explain the possible sequence of a method according to the invention for reworking an optical element, wherein the individual method steps are partly additionally shown in the schematic representations of Fig. 2a-2d are illustrated.

[0051] The starting point of the method according to the invention is the requirement for a repair or reworking of an optical element which has already been used in an optical system such as a projection lens of a microlithographic projection exposure system or a mask inspection system and which has previously been customized for this system (hereinafter referred to as the “original optical system”) typically by means of pass processing. This Fig.The optical element, which is only schematically illustrated in Figure 2a and designated 200, comprises, in the exemplary embodiment, a first carrier layer 202 made of silicon dioxide (SiO2) and a first functional layer 203 on a substrate 201. Depending on the type of optical element, this layer may be, for example, an anti-reflective layer (AR layer). Additional layers (not shown), such as adhesion promoter layers, may be provided in the layer structure.

[0052] After the removal of the optical element 200 from the original optical system in step S100, according to the invention, in step S110, the first functional layer 203 is overcoated with an adaptation layer system 204, wherein a prior decoating or removal of the first functional layer 203 is explicitly dispensed with.

[0053] In step S120, a carrier layer 205 is applied to the matching layer system 204 (in the example also made of SiO2).

[0054] The additional layer structure of adaptation layer system 204 and carrier layer 205 applied in this way is referred to in the context of the present invention as adaptation layer system 210 (cf. the Fig. 2b-d).

[0055] The matching layer system 204 adapts, in a wave-mechanical view, the complex conductance of the previous first functional layer 203 to the complex conductance of the carrier layer 205, which makes it possible to leave the first functional layer 203 in the layer structure without significantly impairing the optical properties of the element 200 as a whole.

[0056] The matching layer system 204 preferably consists - even if this is not shown in the schematic Fig. 2a-d is not shown in detail - from a sequence of several layers of defined thickness, each with different optical properties, in particular a varying, in particular alternating, refractive index.

[0057] The carrier layer 205 is preferably designed such that it allows layer manipulation for subsequent individualization without significantly impairing the optical properties of the matching layer system 204.

[0058] If such a layer manipulation were to be introduced directly into the adaptation layer system 204, this would generally significantly impair its adaptation performance, by up to 10% for typically required layer manipulations.

[0059] Therefore, in the adaptation layer system 210, a functional differentiation is preferably made between an adaptation layer system 204 and the carrier layer 205, so that the quality of the adaptation does not change or changes only very slightly even when layer manipulations on the carrier layer 205 are required.

[0060] The individualization required for the renewed use of the optical element 200 is now carried out on this carrier layer 205. For this purpose, the desired wavefront effect of the optical element 200 in the respective optical system in which the optical element 200 is to be used is first determined (step S130) and then the layer manipulation suitable for achieving this wavefront effect is carried out on the carrier layer 205 (step S140).

[0061] Without the invention being limited thereto, the selection of said layer manipulation can be carried out in particular on the basis of a previously generated lookup table in which the corresponding wavefront effect is listed for a large number of different layer manipulations.

[0062] The layer manipulation itself can be carried out in various suitable ways and can include, for example, the selective removal of layer material, particularly using ion beam machining (IBM), the selective or location-dependent deposition of layer material, or the doping with one or more additional materials. The individualization or matching achieved by layer manipulation can, in particular, include a suitable "aspherization" of the surface of the carrier layer.

[0063] The change in layer thickness brought about by the layer manipulation according to the invention can, for example (and without the invention being limited thereto), be carried out in such a way that the lateral thickness variation corresponds in magnitude to a PV value ("peak to valley") of 40 nm. For this purpose, the carrier layer 205 previously applied according to the invention and subjected to said layer manipulation can have a thickness of at least 100 nm.

[0064] Then, according to Fig. 2c a second functional layer 206 onto the carrier layer 205 in step S150 according to Fig. 1. The presence of the previously overcoated first functional layer 203 is taken into account by adapting the layer design of the second functional layer 206 accordingly. In other words, the second functional layer 206 is designed such that, in cooperation with the first functional layer 203, it ultimately meets the specification requirements.

[0065] A simple example of such a layer sequence could look like the following Table 1: Table 1 No. QWOT material remark 1 Substrat Substrat 2 1 L layer already present in the field 3 1 H 4 1 L 5 1.1 L Adjustment layer system 6 0.9 H 7 1 L 8 4 Carrier layer (customizable) SiO2 or Si 9 1 L new functional layer (AR layer) 10 1 H 11 1 L

[0066] In the layer sequence table above, “QWOT” stands for the quarter-wave optical thickness (= “Quarter Wave Optical Thickness”), L (Low) for a layer with a lower refractive index, e.g. made of MgF2, and H (High) for a layer with a higher refractive index, e.g. made of LaF3 or Al2O3.

[0067] In the above example, the adaptation layer system 204 is formed by layers 5 to 7, the carrier layer by layer 8, whereby layers 5 to 8 together form the adaptation layer system 210.

[0068] When the invention is used for lens systems, the carrier layer consists of SiO2 or when used for mirror systems, it consists of silicon.

[0069] Possibly useful additional adhesion promoter layers are not shown.

[0070] Due to the layer thicknesses of the matching layer (1.1 or 0.9) deviating from the quarter wavelength QWOT = 1 in the example, an adaptation to the “old” AR layer (first functional layer) is possible over a certain angle of incidence range (in the example this is an angle of incidence range of 0 to approx. 20°).

[0071] By using an even larger number of layers, the usable angle of incidence range can be increased or the adaptation and thus the overall anti-reflection effect can be further improved.

[0072] The determination of a suitable layer stack (number, materials, sequences and thicknesses) is conveniently carried out using a computer-aided layer simulation with varying angles of incidence, whereby the previously described adaptation of the complex conductance (admittance) represents a given boundary condition.

[0073] The exact complex conductance of the first functional layer and its angular behavior are generally known from the previous manufacturing process. If it is still unknown, the conductance of the contact medium of the first functional layer can be assumed as an approximation for antireflective coatings.

[0074] This means that, in general, the contact medium is the purge gas in the lithography system and thus the complex conductance is 1. Alternatively, the contact medium could also be the immersion fluid. In this case, its conductance must be used as the starting value.

[0075] From this starting point, the complex conductance of the carrier layer must then be targeted in the admittance diagram.

[0076] If the refractive index of the carrier layer is close to the refractive index of the optical element, the first functional layer can be applied in reverse order as an adjustment layer. This is because an AR layer adapts the complex conductance of the lens to the ambient medium. This means that the admittance profile is mirrored and thus ends up close to the original value.

[0077] Since the complex conductance can only be adjusted precisely for one wavelength and one angle at a time, changes in the matching layer design are usually necessary, or it is often advisable to modify the design or create a new design for the matching layer.

[0078] The design of the first functional layer can generally be used as the second functional layer if the refractive indices of the optical element and the carrier layer are similar. However, even here, a new layer design is generally preferred.

[0079] The thickness of the (new) carrier layer is fundamentally variable and can be customized as described above using various processes, including pass machining, before the “new” AR layer (second functional layer) is applied.

[0080] In the example, the thickness of the carrier layer is a multiple of the thickness of the other layers of the matching layer system, in the example four times a quarter wavelength, i.e. a full wavelength, whereby this thickness, as already mentioned, can be varied to a certain extent without significant disadvantages for the matching efficiency.

[0081] If material-removing processing, such as in particular pass machining, is intended, the thickness of the carrier layer should expediently correspond to at least an expected maximum material removal during layer manipulation (e.g. pass machining) or preferably exceed this amount.

[0082] Fig. Figure 2d schematically shows the fully coated, individualized optical element provided with an adapted second functional layer 206, which in the final step S160 according to Fig. 1 is incorporated into the desired optical system.

[0083] Without limiting the invention to this, it is assumed that this system is another system, which is referred to here as an “optical aiming system”.

[0084] In further embodiments, however, the optical element can also be re-incorporated into the original optical system in which it was previously used after the revision according to the invention.

[0085] The optical system can be, in particular, one for microlithography and, more particularly, a projection lens or a component of an illuminator of a microlithographic projection exposure system or a mask inspection system. Examples of a microlithographic projection exposure system (designed for operation in DUV or EUV) are described below with reference to Fig. 3 and Fig. 4 described.

[0086] Furthermore, the layer design chosen in the exemplary embodiment corresponds to that of a lens designed for operation in the DUV, or at a wavelength of approximately 193 nm. However, the invention is not limited to this, but can also be implemented in further applications in an optical element in the form of a mirror, particularly for operation in the EUV (i.e., at wavelengths less than 30 nm, especially less than 15 nm).

[0087] Fig. 3 shows a schematic representation of a possible structure of a microlithographic projection exposure apparatus 300, which is designed for operation at wavelengths in the DUV range (ie for an operating wavelength of less than 250 nm, in particular less than 200 nm, e.g., approximately 193 nm) and has an illumination device 302 and a projection lens 308.

[0088] The illumination device 302, into which light from a light source 301 enters, is symbolized in a highly simplified manner by lenses 303, 304 and an aperture 305. In the example shown, the operating wavelength of the projection exposure system 300 is 193 nm when using an ArF excimer laser as the light source 301. However, the operating wavelength can also be, for example, 248 nm when using a KrF excimer laser or 157 nm when using an F2 laser as the light source 301.

[0089] Between the illumination device 302 and the projection lens 308, a mask 307 is arranged in the object plane OP of the projection lens 308 and is held in the beam path by a mask holder 306. The mask 307 has a structure in the micrometer to nanometer range, which is imaged onto an image plane IP of the projection lens 308 by the projection lens 308, reduced in size by a factor of 4 or 5, for example. The projection lens 308 comprises a lens arrangement, symbolized only in a highly simplified manner by lenses 309, 310, 311, 312, 320, which defines an optical axis OA.

[0090] A substrate 316, or a wafer, is held in the image plane IP of the projection lens 308. It is positioned by a substrate holder 318 and provided with a light-sensitive layer 315. An immersion medium 350, which may be deionized water, for example, is located between the last optical element 320 of the projection lens 308 on the image plane side and the light-sensitive layer 315.

[0091] Fig. Figure 4 shows a schematic meridional section of the possible design of a microlithographic projection exposure system designed for operation in the EUV.

[0092] According to Fig.4, the projection exposure system 1 comprises an illumination device 2 and a projection lens 10. The illumination device 2 serves to illuminate an object field 5 in an object plane 6 with radiation from a radiation source 3 via an illumination optics 4. A reticle 7 arranged in the object field 5 is exposed. The reticle 7 is held by a reticle holder 8. The reticle holder 8 can be displaced, in particular in a scanning direction, via a reticle displacement drive 9. In Fig. For illustrative purposes, a Cartesian xyz coordinate system is shown in Figure 4. The x-direction runs into the drawing plane. The y-direction runs horizontally and the z-direction runs vertically. The scanning direction runs in Fig. 4 along the y-direction. The z-direction runs perpendicular to the object plane 6.

[0093] The projection lens 10 is used to project the object field 5 into an image field 11 in an image plane 12. A structure on the reticle 7 is projected onto a light-sensitive layer of a wafer 13 arranged in the region of the image field 11 in the image plane 12. The wafer 13 is held by a wafer holder 14. The wafer holder 14 can be displaced, in particular along the y-direction, via a wafer displacement drive 15. The displacement of the reticle 7, on the one hand, via the reticle displacement drive 9, and the displacement of the wafer 13, on the other hand, via the wafer displacement drive 15, can be synchronized with each other.

[0094] Radiation source 3 is an EUV radiation source. Radiation source 3 emits, in particular, EUV radiation, which is also referred to below as useful radiation or illumination radiation. The useful radiation has, in particular, a wavelength in the range between 5 nm and 30 nm. Radiation source 3 can be, for example, a plasma source, a synchrotron-based radiation source, or a free-electron laser (FEL). The illumination radiation 16 emanating from the radiation source 3 is bundled by a collector 17 and propagated through an intermediate focus in an intermediate focal plane 18 into the illumination optics 4. The illumination optics 4 has a deflection mirror 19 and, downstream of this in the beam path, a first (field) facet mirror 20 (with schematically indicated facets 21) and a second (pupil) facet mirror 22 (with schematically indicated facets 23).

[0095] The projection lens 10 has a plurality of mirrors Mi (i= 1, 2, ...), which are numbered according to their arrangement in the beam path of the projection exposure system 1. In the Fig. In the example shown in Figure 4, the projection lens 10 has six mirrors M1 to M6. Alternatives with four, eight, ten, twelve, or a different number of mirrors M1 are also possible. The penultimate mirror M5 and the last mirror M6 each have a passage opening for the illumination radiation 16. The projection lens 10 is a doubly obscured optical system. The projection lens 10 has a numerical aperture on the image side, which can be, for example, greater than 0.5, in particular greater than 0.6, and can be, for example, 0.7 or 0.75.

[0096] The optical element subjected to the layer manipulation according to the invention can be, for example, one of the lenses 309-312, 320 of the projection lens 308 from Fig. 3 or one of the mirrors M1 to M6 of the projection lens 10 from Fig. 4 act.

[0097] Although the invention has been described with reference to specific embodiments, numerous variations and alternative embodiments will become apparent to those skilled in the art, e.g., by combining and / or interchanging features of individual embodiments. Accordingly, it will be understood by those skilled in the art that such variations and alternative embodiments are encompassed by the present invention, and the scope of the invention is limited only by the appended claims and their equivalents. QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] DE 10 2021 201 193 A1

[0013] US 7,170,915 B2

[0013] US 7,629,572 B2

[0013] US 4,533,449

[0013] EP 3 286 595 B1

[0013] WO 2017 / 125362 A1

[0013] DE 10 2017 206 256 A1

[0040]

Claims

[1] Method for reworking an optical element, in particular for microlithography, wherein the optical element (200) has a first functional layer (203), characterized by that the procedure comprises the following steps: a) overcoating the first functional layer (203) with an adaptation layer system (204); b) applying a carrier layer (205) to the matching layer system (204); c) determining a wavefront effect desired for reuse of the optical element (200); and d) optionally performing a layer manipulation on the optical element depending on the desired wavefront effect. [2] Method according to claim 1, characterized by that it further comprises the step: e) applying a second functional layer (206) to the carrier layer (205). [3] Method according to claim 1 or 2, characterized bythat the adaptation layer system (204) is designed such that the complex conductance of the first functional layer (203) is adapted to the complex conductance of the carrier layer (205). [4] Method according to claim 3, characterized by that the matching layer system (204) is formed from a sequence of optical layers of predetermined layer thickness with varying refractive index. [5] Method according to one of claims 2 to 4, characterized by that a layer design of the second functional layer (205) is designed taking into account the existing first functional layer (203). [6] Method according to one of claims 1 to 5, characterized by that step c) of determining the desired wavefront effect comprises determining a system wavefront deviation between an existing system wavefront and a desired system wavefront for an optical target system. [7] Method according to one of the preceding claims, characterized by that the selection of the layer manipulation is carried out as a function of the desired wavefront effect using a previously determined lookup table in which the respective wavefront effect of the optical element (200) is listed for different layer manipulations. [8] Method according to one of the preceding claims, characterized by that the layer manipulation takes place on the adaptation layer system (203) and / or the carrier layer (205) and / or on a possibly provided new, second functional layer (206), wherein a layer manipulation on the carrier layer is preferred. [9] Method according to one of the preceding claims, characterized by that the layer manipulation includes performing a locally varying layer removal. [10] Method according to claim 9, characterized bythat the layer removal takes place from the carrier layer (205) and the layer thickness of the carrier layer (205) corresponds at least to the expected maximum layer removal during the layer manipulation. [11] Method according to one of the preceding claims, characterized by that the layer manipulation comprises performing a locally varying deposition of a layer material. [12] Method according to one of the preceding claims, characterized by that the layer manipulation includes performing a locally varying ion implantation. [13] Method according to one of the preceding claims, characterized by that the first functional layer (203) of the optical element (200) is located on an individualized pass or an existing carrier layer. [14] Method according to one of the preceding claims, characterized by that the carrier layer (205) comprises silicon dioxide (SiO2) or silicon (Si). [15] Method according to one of the preceding claims, characterized by that the layer manipulation is further carried out in such a way that one or more optical properties of the optical element from the following group of optical properties are adapted or optimized to the original values before the method is carried out: - Polarization effect in terms of reflection splitting and / or phase splitting, and / or - reflexive effect, and / or - Transmission effect. [16] Method according to one of claims 1 to 15, characterized by that the optical element (200) is a lens. [17] Method according to one of claims 1 to 15, characterized by that the optical element is a mirror. [18] Method according to one of the preceding claims, characterized by that the optical element (200) is designed for an operating wavelength of less than 250 nm, in particular less than 200 nm. [19] Method according to one of the preceding claims, characterized by that the optical element is designed for an operating wavelength of less than 30 nm, in particular less than 15 nm. [20] Method according to one of claims 1 to 19, characterized by that the optical system is a projection lens (10, 308) of a microlithographic projection exposure system (1, 300). [21] Method according to one of claims 1 to 19, characterized by that the optical system is a projection lens of a mask inspection system. [22] Method according to one of claims 1 to 19, characterized by that the optical system is an optical component of an illuminator of a microlithographic projection system. [23] Optical element, in particular for microlithography, which is formed by carrying out a method according to one of the preceding claims. [24] An optical system comprising an optical element according to claim 23.

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