Method for characterizing diffractive optical element and method for producing diffractive optical element implementing characterization method

Abstract

A diffractive optical element (DOE) has first and second structural portions for defining first and second optical path lengths of used radiation incident on the DOE, the first and second optical path lengths being different from each other. The first structural portion and the second structural portion alternately appear on the use surface of the DOE. During characterization of the diffractive optical element, a raw DOE (10) is first provided. Then, first and / or second structural parts associated with each other on the original DOE are determined, and based on the first and / or second structural parts, associated first isolation structural parts completely isolated from the other first structural parts via the second structural parts are determined, and / or a mutually associated second isolation structure portion completely isolated from other second structure portions via the first structure portion. During fabrication of the correspondingly characterized DOE, at least one contact member may be applied to the original DOE for eliminating undesired isolation between the structural portions. This results in a possibility that diffractive optical elements with more precise diffraction can be produced, which in turn can be used to characterize the surface shape of the optical surface of the optical element.

Description

[0001] This patent application claims the priority of German patent application DE 10 2022 207 138.7, the content of which is incorporated herein by reference. Summary of the invention

[0002] The present invention relates to a method for characterizing a diffractive optical element. The present invention also relates to a method for manufacturing a diffractive optical element by implementing such a characterization method. The present invention also relates to a diffractive optical element manufactured by such a method, and a method for characterizing the surface shape of an optical surface of an optical element performed by such a diffractive optical element. Background Art

[0003] Diffractive optical elements for characterizing the surface shape of optical surfaces of optical elements are known from the professional article “Quasi-absolute measurement of aspheres with a combined diffractive optical element as reference” by Simon et al. (Applied Optics, Vol. 45, No. 34, 2006, pp. 8606 to 8612), from the professional article “Redistribution of outputweighting coefficients for complex multiplexed phase-diffractive elements” by Liu et al. (Optics Express, Vol. 12, No. 19, 2004, pp. 4347 to 4352), and from DE 10 2019 215 707A1 and the references specified therein. Summary of the invention

[0005] It is an object of the present invention to provide the possibility of producing a more accurately diffractive diffractive optical element which in turn can be used to characterize the surface shape of an optical surface of an optical element.

[0006] This object is achieved according to the invention by a characterization method having the features specified in claim 1 .

[0007] The diffractive optical element (DOE) characterized during the method may be a phase mask.

[0008] According to the invention, it has been found that during the DOE manufacturing method, the arrangement and configuration of the first and second structure parts (i.e. the two types of structure parts) defined for optimal diffraction of the DOE is deteriorated in that isolated structure parts occur, which are isolatedly surrounded by structure parts of the respective other structure type, so that they have no contact or insufficient contact with structure parts of the same type. In particular in the case where at least one structure part type is made of an electrically conductive material, this can lead to undesirable differences in the electrical potentials between structure parts of the same type and therefore in particular to undesirable changes in the structure depth and corresponding undesirable changes in the diffraction efficiency and / or the phase / wavefront.

[0009] The characterization method makes it possible to determine the corresponding isolating structure portions in which damaging manufacturing inhomogeneities may occur, in particular due to potential differences, on an original DOE which is an intermediate product of the DOE to be produced and which can be taken into account when the DOE is produced from the intermediate product by using corresponding compensation measures.

[0010] The provided DOE may be an original DOE, which exists before the actual production of the diffractive structure parts, for example in the form of a special binary computer bitmap representing the arrangement and configuration of the various structure parts. At least one type of structure part may be locally defined, for example, by a mask material on one type of structure part. At least one of the structure part types or the mask material defining it may be made of a conductive material. The first structure part may be defined by a hard mask structure for preparing an etching process for producing the DOE. The mask material may be a chrome hard mask. For example, if the DOE is in the form of a reflection grating, the first structure part may be a raised structure area. If the DOE is in the form of a phase grating, the first structure part may be a portion of a first larger optical transmission path length, such as a thicker layer area of ​​an optical material. If the DOE is in the form of a reflection grating, the second structure part may be a recessed structure area. If the DOE is in the form of a phase grating, the second structure part may be a portion of a second smaller optical transmission path length, such as a less thick layer area of ​​an optical material. The DOE may be in the form of a computer generated hologram (CGH).

[0011] The first isolating structure portion has only the structure type of the first structure portion. The second isolating structure portion has only the structure type of the second structure portion.

[0012] The first structural part and the second structural part appear alternately or sequentially on the use surface of the DOE. The change period between the various structural parts is usually not constant, but can vary in particular over a large order of magnitude.

[0013] The method for determining and determining isolated structural parts according to claim 2 is suitable as long as the arrangement and configuration of structural parts on all used surfaces can be studied within the scope of binary representation. The study can be realized at the pixel level. Alternatively or additionally, the investigation can be carried out on an area with polygonal boundaries. Conversely, alternatively or additionally, the study can be carried out on an area defined by several support points and can have curved boundaries in particular by spline functions between the support points. In general, information about the area to be studied of the structural part can also be present in vector form.

[0014] The determination method according to claim 3 makes it possible to very significantly reduce the data during the investigation of the first and second structural parts. Compared to an investigation at the pixel level of the entire binary representation of the structural parts, the data can also be reduced by 10 4 to 10 6 For scaling the phase function representation, the scaling factor used may be the wavelength of the wave function representation of the structure portion and / or the spatial coordinate of the phase function representation. The scaling factor may be selected in the range between 100 and 500, which results in a corresponding reduction in the data, which may include the square of the scaling factor.

[0015] In the case of a determination and decision method according to claim 4, the identified environment can be exploited to the effect that the presence of isolated structural parts that may interfere is caused by a beat frequency effect represented by a wave function. This can be exploited by using a merit function that can include a linear combination of basis vectors describing the structural parts. As far as the area to be investigated is represented in binary, the above explanations regarding claim 2 apply.

[0016] The advantages of the DOE production method according to claim 5 correspond to those already explained above with reference to the characterization method, which is part of the manufacturing method. Using at least one applied contacting means, undesired potential differences between mutually isolated structural parts of the same type and thus undesired isolation between structural parts can be eliminated. In the subsequent finishing of the DOE, in particular in the context of etching methods, there are no undesired inhomogeneities, such as inhomogeneities in the etching depth, due to undesired potential differences.

[0017] At least one contact element according to claim 6 makes it possible to eliminate potential differences of a respective plurality of previously mutually isolated isolating structure portions.

[0018] The contact means according to claim 7, which may have the form of an elongated needle and / or a line segment, has proven successful in practice. It is usually sufficient to apply a single contact means in order to avoid undesired potential differences on the use surface of the DOE.

[0019] This applies in particular to a contact element having a length according to claim 7 .

[0020] A plurality of contact elements has also proven successful in practice according to claim 8. In this respect, locally mutually isolated structural parts of the same type are connected to one another via a respective one of the plurality of contact elements.

[0021] A contact element according to claim 9, which may be in the form of a short pin, has proven successful for applying a plurality of contact elements.

[0022] The advantages of the DOE according to claim 10 correspond to those already explained above with reference to the characterization method and also with reference to the production method using the characterization method.

[0023] The same applies to the characterization method according to claim 11 , which also leads to more precise results due to the more precise diffraction DOE. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Exemplary embodiments of the present invention will be explained in more detail below with reference to the accompanying drawings, in which:

[0025] Figure 1 shows a detail of a used surface of a diffractive optical element (DOE) having a shaded patterned first structure portion represented at pixel level, and a white second structure portion for defining various optical path lengths of the used radiation incident on the DOE;

[0026] Figure 2 Shown according to Figure 1 A cross section of the structural portion according to line II in a sub-portion of the DOE;

[0027] Figure 3 Schematically shows a plan view of an embodiment of a DOE manufactured without applying contact means connecting the isolated structure parts to each other, wherein the profile parameter "etching depth on manufacture of the structure parts" is depicted in a contour line representation as a function of the position on the DOE;

[0028] Figure 4 The plan view shows the Figure 3 A DOE, wherein the result of the characterization method including the operation of determining and judging mutually adjacent first structural parts and / or second structural parts is depicted in a local detail or candidate area of ​​the DOE;

[0029] Figure 5Results of a variant of the characterization method are shown, including determining mutually adjacent first structural portions and / or second structural portions and determining isolated structural portions by studying a scaled phase function representation of the first structural portion and the second structural portion using a first low scaling factor s;

[0030] Figures 6 to 8 Shows something like Figure 5 a representation of further results of the characterization method of , wherein the structural parts are depicted on a scaled phase function representation with increasing scaling factor s;

[0031] Fig. 9 Again a detail of a DOE having a ring structure with isolated structural parts, that is to say a first and a second structural part of the DOE, which are completely isolated from the other first and second structural parts via the first and second structural parts;

[0032] Figures 10 to 12 A vector addition representation is shown for understanding the merit function used to determine the Fig. 9 The DOE uses isolated structures on the surface as candidate regions (hot spots) where there appear structures with lengths below a defined value ( Fig.10 and Fig.12 ) and above the limit value ( Fig.11 ) is the linear combination of wave vectors under study represented by the phase function of the structural part of the residual vector;

[0033] Fig.13 Shows something like Figure 3 and Figure 4 The representation of the results of a characterization method using Fig.12 determination of candidate regions for studying linear combinations, wherein exclusively those candidate regions on the use surface of the DOE in which studied linear combinations with residual vectors having a length below a defined value occur are highlighted as hot spots;

[0034] Fig.14 A schematic diagram showing an example of isolated structural portions determined by a variation of the characterization method, using alternating examples of first structural portions and second structural portions placed concentrically with each other;

[0035] Fig.15 Shown according to Fig.14 The isolating structure part has a contact member applied in the form of a long needle or line segment for Fig.14 connecting a plurality of previously isolated isolation structure portions to each other;

[0036] Fig.16 Shows something like Fig.15 for connecting multiple contact components via corresponding shorter pin forms according to Fig.14Illustrations of variations of previously isolated insulating structural portions, wherein each of the applied contact components connects at least two previously isolated insulating structural portions to each other; and

[0037] Fig.17 A flow chart of a method for fabricating a diffractive optical element is shown, which selectively utilizes one of three different characterization methods to determine the isolated structure portion on the use surface of the DOE. DETAILED DESCRIPTION

[0038] Figure 1 Details of a diffractive optical element (DOE) 1 are shown, which may be in the form of a computer generated hologram (CGH). The DOE 1 may be used to characterize, in particular measure the surface shape of an optical surface of an optical element, which is not shown. This optical element may be an optical component of a light collector, an illumination optical unit or a projection optical unit of a lithography projection exposure apparatus, in particular for EUV lithography.

[0039] Examples of DOE and surface shape characterization methods are known from the professional article “Quasi-absolute measurement of aspheres with a combined diffractive optical element as reference” by Simon et al. (Applied Optics, Vol. 45, No. 34, 2006, pp. 8606 to 8612), the professional article “Redistribution of output weighting coefficients for complex multiplexed phase-diffractive elements” by Liu et al. (Optics Express, Vol. 12, No. 19, 2004, pp. 4347 to 4352), DE 10 2019 215 707 A1 and the references specified therein.

[0040] according to Figure 1 The DOE 1 has a first structural part 2 and a second structural part 3, wherein the first structural part 2 is Figure 1 The second structure portion 3 is shown as a shaded patterned area in Figure 1 The first structure portion 2 is used to define a first optical path length of the used radiation incident on the DOE. Figure 14 is shown in FIG. 1 by the incident beam arrow 4. The second structure portion 3 is used to define a second optical path length of the used radiation 4 incident on the DOE 1. The second optical path length is different from the first optical path length defined via the first structure portion 2. This results in a corresponding diffraction effect for the used radiation 5 emerging from the DOE 1, which is Figure 1 This is again shown by a bundle of arrows.

[0041] Two structural parts 2, 3, that is to say two structural part types that differ in a defined optical path length, appear alternately or are arranged alternately on the use surface 6 of the DOE 1. The DOE 1 can be in the form of a binary DOE in particular. The surface area of ​​the first structural part 2 on the use surface 6 corresponds approximately to the surface area of ​​the second structural part 3. The surface ratio between the surface area of ​​the first structural part 2 and the use surface 6 and the entire use surface 6 can be, for example, in the region between 0.3 and 0.7. This area ratio can be different in different use areas of the DOE 1.

[0042] The structural parts 2, 3 have profile details in the region of a few nanometers, for example in the range between 2 nm and 2000 nm, for example between 2 nm and 10 nm or between 10 nm and 2000 nm. In the case of DOE 1, the structural variations (e.g. period or filling level) of the structural parts 2, 3 typically vary on a linear scale in the range between 50 μm and 1 cm, for example between 50 μm and 200 μm, or between 400 μm and 1 cm.

[0043] The structure, in particular the two-dimensional extent of the structure parts 2, 3, is defined by the mask material on one of the structure part types 2, 3. Figure 1 In the example of , this definition of the configuration is achieved by applying a mask material to the location of the first structural portion 2. The mask material is made of an electrically conductive material. The mask material is a chrome hard mask.

[0044] During the etching manufacturing process during the manufacture of the DOE 1, the second structure parts 3 are etched between the first structure parts 2 defined via the hard mask device, with the result that the optical effect of the second structure parts 3 is different from the optical effect of the first structure parts 2 as required in terms of the defined optical path length of the incident radiation 4 used.

[0045] Figure 2 Shown along Figure 1 The section line II in FIG. 2 passes through the cross section of the adjacent structural parts 2 , 3 .

[0046] The head region of the first structure portion 2 (i.e., the positive structure) is protected by a mask material during the manufacturing process. The projection width of the first structure portion 2 is Figure 2The typical etching depth of the second structure part 3 (i.e., the negative structure of DOE 1) is Figure 2 The microgroove region produced as a result of the process for etching the second structure portion 3 is characterized by ed (etching depth). Figure 2 In the embodiment of the present invention, the microgroove region mt is characterized by mt. Such a microgroove region mt can be regarded as a profile deviation from a set point structure having, for example, a rectangular profile. Corresponding set points can also be defined for etching depth and critical dimension. The deviation of etching depth or critical dimension from the corresponding set point can be expressed as deltaED or deltaCD. The potential difference caused by the unconnected parts of the structural part 2 or 3 usually leads to a deviation of the corresponding geometric parameters from the corresponding set point. Depending on the parameters considered, the deviation may have different amplitudes. As has been observed, the difference in potential leads to deviations in etching depth (ed) and profile sidewall angle (swa, sidewall angle).

[0047] The angle of the structural sidewall between the structural levels N1 and N2 defined by the first structural part 2 and the second structural part 3 is Figure 2 As shown by α in FIG. , for the etching depth ed, it holds that: ed = n1 - n2.

[0048] The diffraction effect of the DOE 1 to be defined requires a complex distribution of the first structure portions 2 and the second structure portions 3 on the use surface 6 of the DOE 1 .

[0049] This distribution usually results in a large area of ​​the first structural part 2 and / or the second structural part 3 being mutually adjacent. In particular, a possible result is first isolated structural parts that are mutually adjacent, that is, first structural parts 2 that are completely isolated from other first structural parts 2 via the second structural part 3. As an alternative or in addition, a second isolated structural part, that is, a second structural part 3 that is completely isolated from other second structural parts 3 via the first structural part 2 can be produced.

[0050] Such first and / or second isolation structure portions may have the undesirable effect of changing the etching depth ed.

[0051] Figure 3 The effect of a variable etching depth ed over the entire use surface 6 of a non-inventive embodiment of a DOE 1 is shown, in which case the variation of the etching depth ed is not compensated. Represented within the use surface 6 are contour lines ed showing isovalues ​​of the etching depth ed i Over a large part of the use surface 6, the variation in the etching depth is very small and the etching depth remains practically constant over the use surface 6 in these areas. In the areas 7 where the etching depth varies greatly, the etching depth ed varies locally over the use surface 6 in a largely delimited manner and this is particularly true for the areas with contour lines ed iThe contour lines represent the effect like mountains on a map. Such regions 7 of large etch depth variations are undesirable as this has the undesirable effect of changing the diffraction effect of the DOE 1.

[0052] Figure 4 Shown according to Figure 3 DOE 1, in which the configuration of the first structure portion 2 and the second structure portion 3 is depicted instead of the change in the etching depth ed in the region 7 where the etching depth changes greatly. Figure 3 In area 7, Figure 4 There is a concentric arrangement of first structure parts 21, 22 and second structure part 31 located therebetween. The annular outer first structure part 22 is completely surrounded by the adjacent second structure part 32. On the far side of the region 7 with large etching depth variation, Figure 3 The structural parts 2 and 3 are not depicted.

[0053] It has been shown that corresponding to Figure 3 and Figure 4 The highly varied regions of the etching depth of the region 7 in the embodiment of the present invention can be attributed to the corresponding isolation structure portions in the form of the structure portions 21, 31 and 22, specifically, on the one hand, mutually adjacent first isolation structure portions 21 or 22 which are completely isolated from the other first structure portions 21 via the second structure portions 31 and / or 32, and on the other hand, mutually adjacent second isolation structure portions 31 which are completely isolated from the other second structure portions 32 via the first structure portions 21, 22. In particular, during the etching of the second structure portions 3, the conductive mask material on the first isolation structure portions 21, 22 can be in contact with the other first structure portions 21. i different potentials, and this can lead to a changed etching behavior in the region 7 of highly varying etching depths.

[0054] In the process of the method for characterizing the DOE 1, an original DOE including structural data is first provided, and then the desired DOE 1 is manufactured based on the structural data. The original DOE can be a pixelated binary representation of the DOE, such as a CGH layout (see Figure 1 ). Therefore, the original DOE does not absolutely need to exist as a physically manufactured DOE intermediate product.

[0055] Then, the mutually adjacent first structural parts 2 and / or second structural parts 3 are determined on the original DOE. These mutually adjacent first structural parts 2 and / or second structural parts 3 are used as the first isolated structural parts (e.g. Figure 4 21, 22) and / or mutually adjacent second isolation structure parts (e.g. Figure 4 31) in the basis.

[0056] The isolation structure part 2 is explained below i , 3 i Different variations of this determination and judgment.

[0057] In one variation, this determination and decision can be made by studying the first structural portion 2 of the original DOE at the pixel level. i and the second structural part 3 i Therefore, the binary representation of the structural layout of the original DOE is studied for what structural parts meet the conditions of the first isolation structural part and the second isolation structural part, and then these isolation structural parts are marked on the use surface of the original DOE. After this determination, measures can then be taken to avoid the isolation structural part 2 i and 3 i Undesirable potential difference between.

[0058] In part 2 for determining and judging the isolation structure i , 3 i In another variation of the method, the first structural part 2 can be studied i and the second structural part 3 i This is achieved by using a scaled phase function representation of . This makes possible an approximate scaling of the DOE design. Compared to the first variant explained above, the amount of data to be analyzed can be reduced by, for example, 10,000 to 250,000 times, without causing relevant limitations on the determination of regions 7 with large variations in etching depth. Describe the DOE design:

[0059]

[0060] where r is the position vector with coordinates x and y;

[0061] g j and W j Carries the design information for the structuring of the first structural part 2 and the second structural part 3. W is the wave function and g is the associated weight coefficient.

[0062] In the phase function In Scaling, select the following scaling method:

[0063]

[0064]

[0065] Where s is the scaling factor. Scaling transformation can be understood as the simultaneous scaling of wavelength and pixel size or the scaling of DOE wave design. is the wave vector of the corresponding elementary wave function.

[0066] Figures 5 to 8 The effect of this scaling transformation is shown for various scaling factors s for fixed coordinates x0 , y0 which are in each case located in the center of the detail of the respective subsequent figure.

[0067] Figures 5 to 8 The detail of the DOE 1 shown in FIG. 1 is again a first structural part 2 having a concentric arrangement i and structure part 3 i The sequence starting from the center of the concentric structure is combined with the above Figure 4 The order of explanation is exactly the opposite. Figure 5 In the center of the concentric structure, there is therefore a second structural portion 31.

[0068] Therefore, as above combined Figure 4 As already explained, the first concentric circle starting from the center is the corresponding isolating structure part 3 i and 2 i .

[0069] Figure 5 A representation is shown for a scaling factor s of about 10. The information about the arrangement and configuration of the structural parts 2, 3 is virtually unchanged at this scaling factor relative to the unscaled DOE design.

[0070] Figure 6 shows a phase function and a scaling factor s of 21. Figure 5 Basic information in.

[0071] Figure 7 The information of the scaling factor s=84 is shown. It can also be seen here that Figure 7 In the center, a region 7 with large variations in etching depth is expected.

[0072] Only in Figure 8 At the very high scale factor of 350 in the region selected in , the resolution of the structure is so weak that it can still be seen Figures 5 to 7 Isolation structure as seen in Part 2 i , 3 i No longer visible.

[0073] Up to a scaling factor s in the range between 100 and (depending on the structuring of the original DOE) 500, a scaled phase function representation has proven successful, making it possible to determine and identify regions 7 with large etch depth variations on the use surface 6 of the DOE 1 with high accuracy.

[0074] The scaling factor s is chosen so that the resulting spatial variation of the wave W and weight g remains smaller than the iterative structure part 2 i , 3 i The expected canonical variate.

[0075] By using the scaled phase function Within the region 7 of large variations in etching depth found by the method, an unscaled allocation can then be implemented, as explained above in conjunction with the first variant of the determination and decision method.

[0076] Now Figures 9 to 12 As a basis for explaining the method for determining and judging the mutually adjacent first structural parts 2 and / or second structural parts 3 and judging the corresponding isolation structural parts 2 i , 3 i Another variation of the method.

[0077] Fig. 9 A variant of the DOE 1 is shown again, which has a first structural part 2 i and the second structural part 3 i , first structural part 2 i and the second structural part 3 i In a part of the use surface 6, they are placed annularly relative to each other, as described above, for example by means of Figure 5 Already explained.

[0078] In order to be able to predict whether the use surface 6 of the DOE 1 contains, for example, an isolated structure portion 2 at the spatial coordinates x, y of the use surface 6 i The probability of using the following merit function S:

[0079]

[0080] in is the position vector of the considered position x, y;

[0081] where ν c is the phase function corresponding to the above combination The local wave vector of the wave representation of the structure of DOE 1 is explained as follows;

[0082] k is an integer vector that is tuned from -5 to 5 in the above formula for each of the five waves. That is, linear combinations up to order 5 are investigated. The sum is then evaluated and their lengths are evaluated. These local wave vectors are also called basis functions.

[0083] The basic idea here is that the mutually adjacent first and / or second structural parts 2 i , 3 iThe beats produced by the slow changes in the structure undergo additional modulation. Similar to the moiré effect, the individual waves can be These modulations are generated by the resonance of a linear combination of the local wave vectors , which define the DOE structure, i.e. the contours of the structural parts 2, 3. We sum integer multiples of , and evaluate them to obtain the length (Euclidean norm), that is, the residual vector.

[0084] Figures 10 to 12 An example of such a linear combination is shown in Fig.10 and 12 As depicted in , a total length or residue equal to 0 or close to 0 is obtained. The variable S of the merit function above is calculated according to Fig.10 The position x1, y1 and according to Fig.12 The position x2, y2 is greatly increased because the vector and In the denominator of the merit function S.

[0085] In k c The additional summation over ensures that linear combinations with higher integer values ​​are given less weight than linear combinations with lower integer values. The result is a location-dependent hotspot map On the usage surface 6 of the DOE 1 .

[0086] Fig.13 Show this location's dependent heat map At positions S1, S2, and S3, the merit function S presents correspondingly larger values, such as Fig.13 The contour lines of the merit function in are shown. Position S1 represents a smaller circular hot spot or candidate region, which may contain the isolated structure part 2 i and 3 i Hotspot S2 is an example of a candidate region with an elliptical boundary where an isolated structure part 2 may appear. i , 3 i The hotspot S3 is an example of a longer wavelength variation of the parameter F, that is to say a more extensive candidate region where isolated structure parts 2i, 3i are expected. Candidate or hotspot region S i Corresponding to the above combination Figures 5 to 8 Explain the area with large variation in etching depth 7. Hot spot area S i Also known as the isolation structure part 2 i , 3 i The candidate regions related to the occurrence of .

[0087] Hotspot AreaS i A typical linear scale for the region 7 with a greater variation in etching depth is of the order of 1 mm to 1 cm.

[0088] The same applies to the isolation component 2 i , 3 i order of magnitude.

[0089] In the corresponding Figures 9 to 13 During the determination method based on the merit function S, there exists a linear combination of the basic vectors They are assigned to the basic functions used to describe the DOE structure parts and describe the structure parts 2, 3 in the context of the phase function representation. By evaluating the merit function S, candidate regions S can be determined on the use surface 6 of the DOE 1 i , where the basic vectors studied are Linear combinations of residual vectors with lengths below a defined value occur. Such a defined value may be, for example, a vector length that is less than: a typical basis vector length Simply thresholding relative to S allows a representation with discrete hot spots to be created from the continuous, CGH position-dependent changes in S.

[0090] In the hot spot area S determined in this way i Then, the binary representation of the first structural part 2 and the second structural part 3 of the DOE 1 can be studied at the pixel level, that is, in the determined candidate area S i Inside.

[0091] During the manufacture of a DOE corresponding to the DOE 1 having the first structural portion 2 and the second structural portion 3, the first structural portion 2 and the second structural portion 3 appear alternately on the use surface 6 of the DOE 1, firstly, the original DOE 1 is manufactured. R . The following also refers to Fig.17 A flow chart is provided to explain the method.

[0092] Fig.14 This original DOE 1 with the use surface 6 is shown R .

[0093] Provide the original DOE 1 in step 10 R (See Fig.17 ). Within the scope of this providing step 10, the design information of the configuration of the structural parts 2, 3 of the DOE 1 can be defined in the DOE design computer, in particular at the pixel level in a bitmap. The corresponding representation of the bitmap at the pixel level can have 1000000×1000000 pixels. The number of pixels can also be considerably larger.

[0094] Then, characterize the original DOE 1 according to one of the above methods R .

[0095] At the beginning of the characterization method, first in a checking step 11 a decision is made as to whether sufficient computing power is available to study the entire representation (in particular binary representation) of the first structure portion 2 and the second structure portion 3 of the DOE 1 at the pixel level. If there is sufficient computing power available, in a study step 12 the representation of the first structure portion 2 and the second structure portion 3 is studied completely and in particular at the pixel level, and thereby first structure portions 2 and / or second structure portions 3 adjacent to each other are determined, and thereby isolated structure portions 2 are determined. i , 3 i .according to Fig.14 , the isolation structure part 2 determined in this way i , 3 i In the original DOE 1 R In the region of the usage surface 6 , structural parts 31 , 21 , 32 , 22 and 33 are thus depicted as being concentric with one another.

[0096] After completing the isolation structure part 2 i , 3 i After characterization and in particular determination of the invention, during the manufacturing method, at least one contact component is applied to the original DOE 1 during an application step 13. R (See Fig.17 ). Such contact elements are explained in more detail below based on exemplary embodiments. After applying 13 at least one contact element, the original DOE 1 with at least one applied contact element is then processed during a finishing step 14. R Finishing DOE 1.

[0097] Fig.15 Shown based on Fig.14 Original DOE 1 R Example of a corresponding completed DOE 1.

[0098] During the application step 13, a contact element 15 in the form of a short-circuit is applied to the insulating structure part 2 i , 3 i , so that in particular the first electrically conductive structural parts 21, 22 are connected to the structural part 2 of the DOE 1 externally surrounding the structural part 33. The potential difference between the otherwise isolated structural parts 21, 22 and the surrounding structural parts 2 is eliminated via the electrical contact connection through the contact means 15.

[0099] In accordance with Fig.15 In the embodiment of the present invention, the contact member 15 reaches the edge of the use surface 6. This length of the contact member 15 is not necessary. The length of the contact member 15 only needs to be large enough to span the first structural parts 21, 22 up to the surrounding first structural part 2.

[0100] Thus, the contact component 15 connects the first insulating structural portions 21 and 22 to each other and also connects the first insulating structural portions 21 and 22 to the surrounding first structural portion 2, which are themselves adjacent and completely isolated from the surrounding first structural portion 2 via the second structural portions 31, 32 and 33. The contact component also increasingly connects the second structural portions 31, 32 and 33 to each other, which are themselves connected to the other second structural portions 31, 32 and 33 via the first structural portions 21 and 22. i Complete isolation.

[0101] The contact element 15 has a length L on the use surface 6 which is greater than the length L of the structural part 2. i , 3 i One of the typical ranges F along the contact assembly 15 is ten times. Fig.14 and Fig.15 In the example, the structure part 2 i , 3 i The typical range F is structure part 2 i , 3 i radial range.

[0102] In accordance with Fig.15 Alternative application method 13 (according to Fig.16 ) during which a plurality of shorter contact members 16 are placed in place of the long contact member 15 i Applied to the isolation structural component 2 i , 3 i , in order to flip their isolation and connect them to the surrounding structural parts 2 and 3, respectively. For example, the short contact part 161 connects the first structural part 22 having conductivity to the surrounding structural part 2. The short contact part 162 ensures the same connection and additionally connects the two second structural parts 32 and 33 to each other. The short contact part 163 ensures the corresponding connection. The short contact part 164 connects the second structural parts 31 and 32 and 33 and additionally connects the two first structural parts 21 and 22 to each other.

[0103] The short contact part 165 connects the outermost second structural part 33 to the surrounding second structural part 3. The short contact part 166 connects the first structural part 22 to the first surrounding structural part 2. The short contact part 167 connects all structural parts 2 to each other in any case. i , 3 i Connected to the outer first structural part 2.

[0104] Therefore, the contact member 16 applied i A corresponding one of at least two previously isolated isolation structure parts 2 i , 2 i+1, 2 or 3 i , 3 i+1 , 3 are connected to each other.

[0105] The length of the short contact part 16i on the use surface 6 of the DOE 1 is smaller than the length of one of the structural parts 2i, 3i along the short contact part 16i. i Ten times the typical range.

[0106] Apply contact parts 15, 16 i There is no significant influence on the diffraction behavior of DOE 1, as has been shown from practice.

[0107] The produced DOE 1 can then be used to characterize the surface shape of an optical surface of an optical element, as described, for example, in DE 10 2019 215 707 A1.

[0108] If the result of the checking step 11 is that during a pixel level study of all structures 2, 3 on the surface 6 the available computing power available for the characterization method would be exceeded, a further selection step 18 is performed during the characterization method. Here, a selection is made as to whether the isolated structures 2 i , 3 i Operation and / or identification of hotspots 7 and / or S i operation (wherein this isolation structure portion 2 may occur i , 3 i ) is through the study of Figures 5 to 8 The scaled phase function representation explained is still achieved by studying the linear combination of the basis vectors assigned to the phase function representation of the basis function, as combined above Figures 9 to 13 described.

[0109] In the first case, a scaling step 19 is first performed to scale the phase function A cluster analysis is then performed, that is to say an investigation is made whether a correspondingly scaled phase function representation is present in the existing isolation structure portion. This is done in an investigation step 20. Thereafter, in turn, a contact element 15 or 16 is applied in an application step 13 and the DOE 1 is finished 14, as already explained above.

[0110] In another case, after the selection step 18, the hot spots are detected based on the investigated linear combinations with the aid of the merit function S, as described above with the aid of Figures 9 to 13 This is used to determine the hot spot area S i The linear combination detection step 21 is completed, as shown above. Figures 9 to 13 Explained.

[0111] After the linear combination detection step 21, the hot spot area S is further realized.i The cluster analysis research step 22, and the isolation structure part 2 determined based on this i , 3 i , implementing the applying step 13 and finishing step 14 of DOE 1 as described above.

Claims

1. A method for characterizing a diffractive optical element (DOE) (1, 1 R ), wherein the diffractive optical element comprises: - a first structural portion (2) for defining a first optical path length of the used radiation (4) incident on said DOE (1), a second structural portion (3) for defining a second optical path length of the used radiation (4) incident on the DOE (1), the second optical path length being different from the first optical path length, - wherein the first structural portion (2) and the second structural portion (3) appear alternately on the use surface (6) of the DOE (1), The method comprises the following steps: - Provide (10) original DOE (1 R ), - Determine the original DOE (1 R ), the first structural part (2) and / or the second structural part (3) adjacent to each other on the surface of the substrate, - Based on these determined mutually adjacent first structural parts (2) and / or second structural parts (3), it is determined that: - mutually adjacent first isolation structure parts (2i), which are connected to other first structure parts (2i) via second structure parts (3i) i , 2) completely isolated, and / or - mutually adjacent second isolating structural parts (3i), which are connected to the other second structural parts (3i) via the first structural part (2i) i , 3) Complete isolation.

2. The method according to claim 1, characterized in that By studying (12) the binary representation of the first structural portion (2) and the second structural portion (3), the mutually adjacent first structural portion (2) and / or the second structural portion (3) are determined, and the isolated structural portion (2 i , 3 i ).

3. The method according to claim 1 or 2, characterized in that: By studying (19, 20) the scaling phase function of the first structural part (2) and the second structural part (3) is expressed as Determine the mutually adjacent first structural portion (2) and / or the second structural portion (3), and determine the isolation structural portion (2 i , 3 i ).

4. The method according to claim 1 or 2, characterized in that: The mutually adjacent first structural portion (2) and / or second structural portion (3) are determined by the following, and the isolation structural portion (2 i , 3 i ): - studying (21) linear combinations of basis vectors which are assigned to basis functions and which describe the structural parts (2, 3) in the context of a phase function representation, - In the original DOE (1 R ) is used to determine the candidate area (S i ), in which the linear combination of residual vectors under consideration with a length below a defined value occurs in the candidate region, -Study (22) the candidate region (S i ) within a binary representation of the first structure part (2) and the second structure part (3).

5. A method for manufacturing a diffractive optical element (DOE) (1), the diffractive optical element comprising: - a first structural portion (2) for defining a first optical path length of the used radiation (4) incident on said DOE (1), a second structural portion (3) for defining a second optical path length of the used radiation (4) incident on the DOE (1), the second optical path length being different from the first optical path length, - wherein the first structural portion (2) and the second structural portion (3) appear alternately on the use surface (6) of the DOE (1), The method comprises the following steps: - Provide (10) and generate the original DOE (1 R ); - For the original DOE (1 R ) Implementing the characterization method according to any one of claims 1 to 4; - at least one contact element (15; 16 i ) is applied to the original DOE (1 R ), the contact component connects the following to each other: -- at least two mutually adjacent first isolation structure parts (2 i ), the at least two mutually adjacent first isolation structure parts (2 i ) is determined by the characterization method and via the second structural part (3 i , 3) and other first structural parts (2 i , 2) completely isolated, and / or -- at least two mutually adjacent second isolation structure parts (3 i ), the at least two mutually adjacent second isolation structure parts (3 i ) is determined by the characterization method and via the first structural part (2 i , 2) and other second structural parts (3 i 3) Complete isolation; - from the at least one contact member (15; 16) having an applied i ) of the original DOE (1 R ) finishing (14) the DOE (1).

6. The method according to claim 5, characterized in that At least one of the contact members (15, 167) is applied such that it connects more than two previously isolated insulating structure parts (21, 22, 31, 32, 33) to each other.

7. The method according to claim 5 or 6, characterized in that: The length of the contact element (15) on the use surface (6) is greater than ten times the typical extent (S) of one of the structural parts (2, 3) along the contact element (15).

8. The method according to any one of claims 5 to 7, characterized in that Applying a plurality of said contact components (16 i ), so that the applied contact component (16 i ) connect at least two previously isolated insulating structure parts (21, 22; 31, 32; 32, 33) to each other.

9. The method according to any one of claims 5 to 8, characterized in that The contact member (16 i ) on the use surface (6) is shorter than one of the structural parts (2, 3) along the contact part (16 i )’s typical range.

10. A diffractive optical element (DOE) (1) produced by the method according to any one of claims 5 to 9.

11. A method for characterizing the surface shape of an optical surface of an optical element, implemented by a DOE (1) according to claim 10.

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