JP2024506056A - How to tune optics specifically for microlithography - Google Patents

Abstract

The invention relates to a method for adjusting an optical system, in particular for microlithography, comprising a plurality of optical elements, each provided with an optically effective layer system, in which the optical system provides a predetermined plane during operation. measuring a system wavefront; determining a system wavefront deviation between the measured system wavefront and a target system wavefront; and layer manipulation in at least one of the optical elements to reduce the determined system wavefront deviation. and the steps of performing the method. In this case, according to one aspect, the system wavefront is determined using a predetermined look-up table that lists each wavefront contribution of the at least one optical element to the system wavefront for each layer operation of the layer system of said optical elements. A layer operation suitable for reducing the deviation is selected.

Description

This application claims priority from German patent application no. 10 2021 201 193.4, filed on February 9, 2021. The contents of the German application are incorporated by reference into the text of the present application.

The invention relates in particular to a method for adjusting an optical system for microlithography.

Microlithography is used for the manufacture of microstructured components, such as integrated circuits or LCDs. The microlithography process is carried out in a so-called projection exposure apparatus, which has an illumination device and a projection lens. In this case, an image of a mask (reticle) illuminated by an illumination device is projected by a projection lens onto a substrate (for example, a silicon wafer) coated with a photosensitive layer (photoresist) and placed in the image plane of the projection lens. The mask structure is then transferred to the photosensitive coating of the substrate.

A mask inspection device is used for inspecting a reticle in a microlithographic projection exposure device.

In projection or inspection lenses designed for the EUV range, i.e. for example at wavelengths of about 13.5 nm or about 6.7 nm, the unavailability of suitable light-transmitting and refractive materials makes it difficult to use reflective optics for imaging processes. Used as an optical component.

In the process of developing projection lenses, where resolution is increasing and accuracy requirements are increasing accordingly, the challenges posed by implementing each adjustment method to "fit" each optical system to the specifications using the available degrees of freedom or manipulators. It's getting tougher. Within the meaning of the present invention, "adjustment" refers to the correction of process defects associated with the process of manufacturing the optical system or associated optical element (e.g., poor grinding on a lens element, threading on the optical element or its mount, etc.). It is understood to mean an iterative reduction of optical effects.

Regarding the prior art, see, by way of example only, US Pat.

US Patent No. 7,629,572 U.S. Patent No. 4,533,449 European Patent No. 3 286 595 International Publication No. 2017/125362

The aim of the invention is to provide a method for adjusting an optical system, in particular for microlithography, by which a wavefront effect that can be set as precisely as possible can be achieved.

This object is achieved by a method according to the features of independent patent claim 1.

In one embodiment, the method according to the invention for adjusting an optical system, in particular for microlithography, comprising a plurality of optical elements, each provided with an optically effective layer system, comprises:
measuring a system wavefront provided by the optical system in a predetermined plane during operation;
determining a system wavefront deviation between the measured system wavefront and a target system wavefront;
performing a layer operation on at least one of the optical elements so as to reduce the determined system wavefront deviation, the wavefront contribution of each of the at least one optical element to the system wavefront being reduced to a layer of the layer system of said optical elements. A predetermined look-up table listed for each operation is used to select the appropriate layer operation to reduce the system wavefront deviation.

According to the above aspects, the layer operations suitable for reducing the system wavefront deviation between the measured system wavefront and the target system wavefront in this case are based on a predetermined lookup table and the corresponding layer operations and optical system. is selected by considering the sensitivities stored therein with respect to further manipulators present in the . Each wavefront contribution or resulting wavefront change to the system wavefront compared to the optical design can be listed in this look-up table for each layer operation of the optical element in question or for each configuration of the layer system operated by the present invention. can.

Within the meaning of the present application, the term "layer manipulation" is also understood to mean the deposition of a layer on an optical element that is initially not yet coated.

In one embodiment, the optical element is coated in the step of measuring the system wavefront. In this case, this coating may be a coating of the component in question (a "partial" coating in this sense) that does not yet correspond to the finished layer design. Furthermore, layer operations can also be performed iteratively on different layers of the layer system, with system wavefront characterization being performed between each individual iteration step.

The present invention provides, in particular, for carrying out an adjustment of an optical system made up of a plurality of optical elements with respect to the system wavefront provided by this optical system, in particular in a given plane of operation, so that at least one of these optical elements The concept is that the optical effects or wavefront contributions produced by the layer operations carried out or by the layer systems located in the optical element in question are themselves used as degrees of freedom for adjustment.

In other words, the invention provides a method for determining the relationship between the measured actual system wavefront and the ultimately pursued target system wavefront after the confirmation of the actual system wavefront in a given plane, which is initially carried out at the beginning of the system adjustment. In order to reduce the deviation between It includes the principles of determining how layer operations should be performed.

The present invention particularly differs from conventional approaches in that the optical system has already been incorporated and, in some cases, its optically effective coating has already been applied during the verification of the actual system wavefront performed at the beginning of the system adjustment. The layer manipulations of the optical elements that are measured (i.e. already contributing to the measured actual system wavefront) can be used as adjustment degrees of freedom to improve the overall system wavefront properties or reduce wavefront aberrations. be.

In particular, the concept according to the invention differs from conventional methods in which, firstly, wavefront correction is performed only by processing elements that are not yet integrated into the optical system at the beginning of the adjustment process. In this connection, reference may be made to, for example, US Pat. Furthermore, the concept according to the invention also differs from conventional methods in which modifications are carried out in each individual optical element only to optimize the wavefront or transmission properties of the optical element in question (and not the entire system). In this regard, reference is made to, for example, US Pat.

According to one embodiment, the layer manipulation comprises performing locally differential deposition of layer material on the at least one optical element.

According to yet another embodiment, the layer manipulation includes performing locally differential layer removal from the at least one optical element.

According to yet another embodiment, the at least one optical element includes a sealing layer of silicon dioxide ( _SiO2 ). As explained below, this is particularly advantageous in the case of layer manipulations carried out by layer removal, such as ion beam processing, for example.

According to yet another embodiment, the layer manipulation includes performing locally different ion implantations in at least one optical element.

The invention furthermore provides a method for adjusting an optical system, in particular for microlithography, comprising a plurality of optical elements, each provided with an optically effective layer system.
measuring a system wavefront provided by the optical system in a predetermined plane during operation;
determining a system wavefront deviation between the measured system wavefront and the target system wavefront;
and performing a layer operation on at least one of the optical elements to reduce the determined system wavefront deviation, the layer operation performing locally differential deposition of layer material on the at least one optical element. and/or performing locally different ion implantations in at least one optical element.

The layer system present on at least one optical element during verification of the actual system wavefront can be single layer or multilayer. The invention is further not limited with respect to the specific local region of the optical element or layer system in which the layer manipulation takes place. In particular, the above layer operations can alternatively be carried out on an inner layer within a multilayer system or on a capping layer located on top of a multilayer system or a single layer.

This step of determining a system wavefront deviation between the measured system wavefront and the target system wavefront and the reduction of this deviation can in particular be performed in an iterative process.

According to one embodiment, the step of performing a layer operation on at least one of the optical elements comprises determining the deviation between the given actual value and the target value for at least one further characteristic property of the optical system before the layer operation. carried out to reduce This at least one further characteristic property of the optical system may in particular include the reflection behavior and/or the transmission behavior of the optical system.

The invention furthermore provides a method for adjusting an optical system, in particular for microlithography, comprising a plurality of optical elements, each provided with an optically effective layer system.
measuring a system wavefront provided by the optical system in a predetermined plane during operation;
determining a system wavefront deviation between the measured system wavefront and a target system wavefront;
performing a layer operation on at least one of the optical elements to reduce the determined system wavefront deviation, the step of performing a layer operation on the at least one optical element further comprising It also relates to a method carried out to reduce the deviation between the value and the target value for at least one further characteristic property of the optical system.

According to one embodiment, the step of performing a layer manipulation on the at least one optical element is further performed to modify the polarization effect of the optical system.

According to one embodiment, the step of performing the layer operation on at least one optical element further comprises determining the reflection behavior of the optical system, each deviation between the actual value given before the layer operation and the target value. This is done to reduce each of the transmission behavior and the polarization effects of the optical system.

According to one embodiment, at least one of the optical elements on which the layer manipulation is performed is a lens element.

According to one embodiment, at least one of the optical elements on which the layer manipulation is performed is a mirror.

The optical system may in particular be an imaging system. In this case, the predetermined plane may be the image plane of this imaging system.

According to one embodiment, the optical system is designed for an operating wavelength of less than 250 nm, especially less than 200 nm.

According to yet another embodiment, the optical system is designed for an operating wavelength of less than 30 nm, in particular less than 15 nm.

The invention further relates to a microlithography optical system formed by carrying out a method having the above characteristics. The optical system can be a projection lens of a microlithography projection exposure apparatus or a projection lens of a mask inspection apparatus.

Further developments of the invention are apparent from the description and the dependent claims.

The invention will be explained in more detail below on the basis of exemplary embodiments shown in the accompanying drawings.

2 shows a flow diagram illustrating a possible sequence of the method according to the invention; FIG. 1 shows a schematic diagram illustrating a possible structure of an optical element subjected to layer manipulation according to the invention in an exemplary embodiment; FIG. 3a, 3b illustrate the variation of the optical properties of the optical element from FIG. 2 manipulated with respect to the layer system, which can be achieved by the layer manipulation according to the invention. 4a, 4b illustrate the variation of the optical properties of the optical element from FIG. 2 manipulated with respect to the layer system, which can be achieved by the layer manipulation according to the invention. 5a, 5b illustrate the variation of the optical properties of the optical element from FIG. 2 manipulated with respect to the layer system, which can be achieved by the layer manipulation according to the invention. 6a, 6b illustrate the variation of the optical properties of the optical element from FIG. 2 manipulated with respect to the layer system, which can be achieved by the layer manipulation according to the invention. 1 shows a schematic diagram of a possible structure of a microlithographic projection exposure apparatus designed for DUV operation. 1 shows a schematic diagram of a possible structure of a microlithographic projection exposure apparatus designed for EUV operation.

FIG. 1 shows a flow diagram illustrating a possible sequence of the method according to the invention for adjusting an optical system.

The adjustment according to the invention is carried out after providing a corresponding optical system with a plurality of optical elements mounted and arranged in the light beam path and already provided with an optically effective coating, the geometry of each coating as well as of the optical element being adjusted. The optical shape and spacing are set according to the predetermined optical design. The adjustment process is carried out in particular to achieve the specifications defined for each specific application with respect to the system wavefront presented by the system during operation, and this is further carried out in an iterative process using the available degrees of freedom.

The optical system to be adjusted can in particular be a microlithographic optical system, more particularly a projection lens of a microlithographic projection exposure apparatus or a mask inspection apparatus. An example of a microlithographic projection exposure apparatus (designed for DUV and EUV operation, respectively) is described below with reference to FIGS. 7 and 8.

At the start of the adjustment method according to the invention, step S110 first comprises measuring the (actual) system wavefront provided by the optical system in a predetermined plane (e.g. the imaging plane of the projection lens forming the optical system). . In step S120, this actual system wavefront is compared with the required target system wavefront according to a predetermined specification to determine the system wavefront deviation.

In step S130, layer manipulation of at least one optical element of the optical system is then performed to reduce the system wavefront deviation. In this case, the layer manipulation may in particular include carrying out locally different layer removals from the optical element in question, carrying out locally different depositions of layer materials on said element, and/or carrying out locally different ion implantations (e.g. , plasma immersion meion implantation).

The above layer manipulations are performed in such a way as to ultimately achieve the required specifications regarding the system wavefront provided by the optical system during operation. For this purpose, in order to determine the appropriate layer manipulation, the wavefront contribution of each optical element in question to the system wavefront is determined for each configuration of the manipulated layer system of said optical elements and possibly present in the optical system. It is also possible to consider already predetermined look-up tables listed for further manipulators. In still other embodiments, each currently set system wavefront can be measured and compared to a target system wavefront in an iterative process that also repeatedly performs layer operations.

What is essential to the invention here is that during the adjustment of the optical system, the layer manipulations carried out are themselves used as adjustment degrees of freedom. In this case, the optical element undergoing layer manipulation is already integrated into the optical system during the first measurement of the actual system wavefront, so that the wavefront contribution of said optical element is also incidentally taken into account from the beginning during the adjustment. Ru.

For the modification of the optical properties of optical elements manipulated with respect to the layer system, which can be achieved by layer manipulation according to the invention, we first consider the schematic diagram of FIG. 2 and FIGS. 3a, 3b, 4a based on certain exemplary embodiments. , 4b, FIGS. 5a, 5b and 6a, 6b. Reference is made herein by way of example to a particular layer design of an optical element operated in accordance with the present invention, which will be described in more detail with reference to FIG. There are no limitations on the material used or the layer thickness. For further suitable layer materials, see, for example, US Pat. No. 10,642,167 and US Pat. No. 5,963,365.

Furthermore, the layer design selected in the exemplary embodiment corresponds to that of a lens element configured for DUV or operation at a wavelength of about 193 nm. However, the invention is not limited thereto, and in further applications it can also be realized with optical elements in the form of mirrors, in particular for operation in the EUV (i.e. wavelengths below 30 nm, in particular below 15 nm).

In the exemplary embodiment of FIG. 2, optical element 200 on substrate 201 comprises a layer system of layers 202-206, the respective materials and layer thicknesses specified in Table 1.

The configuration of the sealing layer 206 (located farthest from the substrate 201) made of amorphous silicon dioxide (SiO ₂ ) selected in the above layer design according to Table 1 and FIG. In the case of layer manipulations carried out by layer removal, such as processing, the directional dependence of the layer removal process (as occurs when using sealing layers that are not amorphous or have an at least partially crystalline phase, e.g. with a columnar structure) This is advantageous in that isotropic layer removal can be achieved by avoiding this. However, in still other embodiments (particularly in the case of lamination operations by depositing layer materials), other materials can also be used as the material of the sealing layer, such as for example crystalline magnesium fluoride ( _MgF2 ). Table 2 shows a possible layer design in this respect with a substrate made of SiO ₂ and a sealing layer made of MgF ₂ .

Merely by way of example, Table 3 shows a possible layer design with a substrate made of SiO ₂ and a sealing layer made of SiO ₂ .

The present invention is not limited to adjusting only the wavefront characteristics of an optical system. Rather, further adjustments may be made to improve further properties of the optical system, in particular reflection behavior and/or transmission behavior. In this case, the investigations carried out by the inventors have shown that the above-mentioned further (eg reflection or transmission) properties can also be improved or optimized by layer manipulation according to the invention in the same adjustment method.

In the figures described below to illustrate the modification of the optical properties of the optical element 200 manipulated with respect to the layer system, which can be achieved by the layer manipulation according to the invention, the behavior of unpolarized light incident on the optical element 200 is shown in Figures 3a, 3b. and FIGS. 4a, 4b, while the dependence on the polarization state is considered in FIGS. 5a, 5b and 6a, 6b.

3a, 3b show the changes in phase (FIG. 3a) and reflectance (FIG. 3b) that occur for thickness changes ranging from -2 nm to +2 nm for the above exemplary embodiment from FIG. 2 and Table 1. . In this case, the negative sign of the thickness change corresponds to the reduction in layer thickness achieved by layer manipulation. Furthermore, from now on, the incident angle is set to 15°.

As is evident from FIG. 3a, a phase change of about 1.5 nm can be achieved with a layer thickness change of 2 nm. At the same time, according to FIG. 3b, with such a thickness change of 2 nm, a change in reflectance of a value of about 0.15 percentage points is within the acceptable range. Furthermore, by appropriate modification or optimization of the layer design, reflectance changes can be made less sensitive to thickness changes.

According to Fig. 4a, b, the dependence of the phase and reflectance changes achieved by the layer manipulation according to the invention on the angle of incidence is shown, based on a thickness change of 1.5 nm, respectively, as an example. . As is evident from the scale chosen for the phase values in FIG. 4a, the phase change achieved in the case of the layer operation described above is virtually independent of the angle of incidence. Note that with respect to the reflectance changes achieved according to Fig. 4b, there is a change in sign as a function of the angle of incidence.

As is clear from FIGS. 5a, b, the dependence of the phase change achieved in the case of layer manipulation according to the invention on the thickness change is substantially independent of the polarization state of the electromagnetic radiation incident on the corresponding optical element. It's irrelevant. On the other hand, it is clear that there is a certain difference in the profile as a function of the thickness change, depending on whether the electromagnetic radiation is s-polarized or p-polarized, with respect to the respective achieved reflectance changes.

According to Fig. 6a, b, the difference between s- and p-polarization achieved in terms of phase change (Fig. 6a) and reflectance change (Fig. 6b) becomes more pronounced as the angle of incidence increases. It is clear from this that the application to optical elements with relatively large angles of incidence in the light beam path is advantageous for realizing the layer manipulation according to the invention when there is also a desired change in the polarization state.

FIG. 7 shows a microlithographic projection exposure device designed for operation at wavelengths in the DUV range (i.e. for operating wavelengths below 250 nm, in particular below 200 nm, e.g. about 193 nm) and comprising an illumination device 702 and a projection lens 708. 7 shows a schematic diagram of a possible structure of a device 700.

An illumination device 702 into which light from a light source 701 enters is represented in a very simplified manner by lens elements 703 and 704 and an aperture 705. The operating wavelength of the projection exposure apparatus 700 in the illustrated example is 193 nm when an ArF excimer laser is used as the light source 701. However, the operating wavelength may also be, for example, 248 nm when using a KrF excimer laser as the light source 701 and 157 nm when using an _F2 laser. A mask 707 is arranged between the illumination device 702 and the projection lens 708 on the object plane OP of the projection lens 708, and the mask 707 is held in the beam path by a mask holder 706. The mask 707 has a structure in the micrometer to nanometer range that is imaged by the projection lens 708 on the image plane IP of the projection lens 708 with a reduction of, for example, 1/4 or 1/5. The projection lens 708 includes a lens element structure that defines the optical axis OA, and the lens element structure is also represented in a very simplified manner by lens elements 709, 710, 711, 712, and 720. do not have.

A substrate 716 or wafer provided with a photosensitive layer 715 and positioned by a substrate holder 718 is held at the image plane IP of the projection lens 708 . An immersion medium 750, which can be, for example, deionized water, is located between the optical element 720 of the last positioned projection lens 708 on the image side and the photosensitive layer 715.

FIG. 8 schematically shows, in meridional section, a possible structure of a microlithographic projection exposure apparatus designed for EUV operation.

According to FIG. 8 , the projection exposure apparatus 1 includes an illumination device 2 and a projection lens 10 . The illumination device 2 serves to illuminate an object field 5 of an object plane 6 with radiation from a radiation source 3 by means of an illumination optical unit 4 . Here, the reticle 7 placed in the object field 5 is exposed. Reticle 7 is held by reticle holder 8 . The reticle holder 8 is displaceable by means of a reticle displacement drive 9, in particular in the scanning direction. For illustration purposes, an orthogonal xyz coordinate system is shown in FIG. The x direction extends towards the plane of the figure. The y direction extends horizontally, and the z direction extends vertically. The scanning direction extends along the y direction in FIG. The z direction extends perpendicularly to the object plane 6.

The projection lens 10 serves to image the object field 5 into an image field 11 of an image plane 12 . The structures on the reticle 7 are imaged onto a photosensitive layer of the wafer 13 located in the area of the image field 11 of the image plane 12 . Wafer 13 is held by wafer holder 14 . The wafer holder 14 is displaceable by means of a wafer displacement drive 15, in particular along the y-direction. Firstly, the displacement of the reticle 7 by the reticle displacement drive 9 and, secondly, the displacement of the wafer 13 by the wafer displacement drive 15 can be carried out in a mutually synchronous manner.

Radiation source 3 is an EUV radiation source. The radiation source 3 emits, in particular, EUV radiation, also referred to below as use radiation or illumination radiation. In particular, the radiation used has a wavelength in the range from 5 nm to 30 nm. The 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 originating from the radiation source 3 is focused by the collector 17 and propagates through the intermediate focus of the intermediate focal plane 18 to the illumination optical unit 4 . The illumination optical unit 4 comprises a deflection mirror 19, a first (field) facet mirror 20 (with a facet 21 schematically shown) arranged downstream thereof in the beam path, and a second (pupil) facet mirror 22 (schematically shown). ) having a facet 23 shown in FIG.

The projection lens 10 includes a plurality of mirrors Mi (i=1, 2, . . . ), which are numbered consecutively according to their arrangement in the beam path of the projection exposure apparatus 1. In the example shown in FIG. 8, the projection lens 10 includes six mirrors M1 to M6. Replacements with 4, 8, 10, 12 or any other number of mirrors Mi are likewise possible. The penultimate mirror M5 and the last mirror M6 each have a passage aperture for the illumination radiation 16. Projection lens 10 is a double-shielded optical unit. The projection lens 10 has an image-side numerical aperture which may be greater than 0.5, in particular greater than 0.6, for example 0.7 or 0.75, by way of example only.

The optical element subjected to layer manipulation according to the invention can be, for example, one of the lens elements 709-712, 720 of the projection lens 708 from FIG. 7 or one of the mirrors M1-M6 of the projection lens 10 from FIG. .

Although the invention has been described with reference to particular embodiments, numerous variations and alternative embodiments will become apparent to those skilled in the art, for example by combining and/or interchanging features of the individual embodiments. Probably. It will therefore be understood by those skilled in the art that such modifications and alternative embodiments are encompassed by the present invention, and that the scope of the invention is limited only within the meaning of the appended claims and their equivalents. Ru.

Claims (23)

A method for adjusting an optical system, in particular for microlithography, comprising a plurality of optical elements each provided with an optically effective layer system, comprising:
a) measuring the system wavefront provided by the optical system in a predetermined plane during operation;
b) determining a system wavefront deviation between the measured system wavefront and a target system wavefront;
c) performing a layer operation on at least one of the optical elements to reduce the determined system wavefront deviation, the wavefront contribution of each of the at least one optical element to the system wavefront A method in which a layer operation suitable for reducing the system wavefront deviation is selected using a predetermined look-up table listing each layer operation of the layer system of the device. 2. A method according to claim 1, characterized in that the optical element is coated during the measurement of the system wavefront in step a). 3. A method according to claim 1 or 2, characterized in that the layer manipulation comprises performing locally differential deposition of layer material on the at least one optical element. A method according to any one of claims 1 to 3, characterized in that the layer manipulation comprises performing locally differential layer removal from the at least one optical element. Method according to any one of claims 1 to 4, characterized in that the at least one optical element comprises a sealing layer of silicon dioxide (SiO ₂ ). A method according to any one of claims 1 to 5, characterized in that the layer manipulation comprises performing locally different ion implantations in the at least one optical element. A method for adjusting an optical system, in particular for microlithography, comprising a plurality of optical elements each provided with an optically effective layer system, comprising:
a) measuring the system wavefront provided by the optical system in a predetermined plane during operation;
b) determining a system wavefront deviation between the measured system wavefront and a target system wavefront;
c) performing a layer operation on at least one of said optical elements to reduce said determined system wavefront deviation, said layer operation comprising localized layering of layer material to said at least one optical element. and/or performing locally different ion implantations on said at least one optical element. 8. A method according to any one of claims 1 to 7, in which the wavefront contribution of each of the at least one optical element to the system wavefront is listed for each layer operation of the layer system of the optical element. A layer operation suitable for reducing the system wavefront deviation is selected using a look-up table. A method according to any one of claims 1 to 8, characterized in that determining the system wavefront deviation between the measured system wavefront and the target system wavefront is performed in an iterative process. 10. The method according to claim 1, wherein the step of performing a layer operation on the at least one optical element comprises determining the deviation between the given actual value and the target value before the layer operation. A method characterized in that it is carried out to reduce at least one further characteristic property of the optical system. A method for adjusting an optical system, in particular for microlithography, comprising a plurality of optical elements each provided with an optically effective layer system, comprising:
a) measuring the system wavefront provided by the optical system in a predetermined plane during operation;
b) determining a system wavefront deviation between the measured system wavefront and a target system wavefront;
c) performing a layer operation on at least one of the optical elements to reduce the determined system wavefront deviation, wherein performing a layer operation on the at least one optical element comprises: A method carried out to reduce the deviation between a previously given actual value and a setpoint value for at least one further characteristic property of the optical system. 12. A method according to claim 10 or 11, characterized in that the at least one further characteristic property of the optical system comprises a reflection behavior and/or a transmission behavior of the optical system. A method according to any one of claims 1 to 12, characterized in that the step of performing a layer manipulation on the at least one optical element is further carried out in such a way as to modify the polarization effect of the optical system. Method. 14. A method according to any one of claims 1 to 13, in which the step of performing a layer operation on the at least one optical element further comprises the step of performing a layer operation on the at least one optical element. A method, characterized in that it is carried out in such a way that deviations are reduced in each of the reflection behavior of the optical system, the transmission behavior of the optical system and the polarization effect of the optical system. Method according to any one of claims 1 to 14, characterized in that the at least one optical element on which layer manipulation is performed is a lens element. Method according to any one of claims 1 to 14, characterized in that at least one of the optical elements on which layer manipulation is performed is a mirror. A method according to any one of claims 1 to 16, characterized in that the optical system is an imaging system. 18. The method of claim 17, wherein the predetermined plane is an image plane of the imaging system. Method according to any one of claims 1 to 18, characterized in that the optical system is designed for an operating wavelength of less than 250 nm, in particular less than 200 nm. A method according to any one of claims 1 to 19, characterized in that the optical system is designed for an operating wavelength of less than 30 nm, in particular less than 15 nm. Microlithography optical system formed by carrying out the method according to any one of claims 1 to 20. 22. The optical system according to claim 21, wherein the optical system is a projection lens of a microlithography projection exposure apparatus. The optical system according to claim 22, wherein the optical system is a projection lens of a mask inspection device.

Images