Method and apparatus for identifying mark field and position

Abstract

To provide a device and a method for measuring a substrate that enable more accurate or more efficient identification of a position of a structured or feature portion on the substrate.SOLUTION: A mark (1) includes at least two location marks (2) that contain information about a location of each location mark (2) within a mark field (4) and at least one position mark (3) assigned or assignable to one of the location marks (2). In addition, in a device for identifying an X-Y-position of a structural feature (11c) of a structured part (11) arranged on a substrate (7), the X-Y-position is identifiable relative to the mark field (4) fixed with respect to the substrate.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The invention relates to a mark field according to claim 1, to a device for determining the XY-position of structural features of a structured part arranged on a substrate according to claim 8 and to a corresponding method according to claim 9.

[0002] In industry, knowledge of the position of a structure on a substrate is of crucial importance. Of particular interest is the difference between the real actual position of the structure and the ideal target position. To determine the actual position of the structure, a coordinate system can be introduced and the position of the structure can be expressed with respect to this coordinate system. In most cases, the coordinate system is object-fixed, i.e. assigned to the substrate. This coordinate system is referred to below as the substrate coordinate system.

[0003] However, in order to be able to measure all the structures, a relative movement must be performed between the substrate and the measurement system, in particular an optical system with a camera. This is necessary because not all structures are within the field of view of the measurement system. If all the structures to be measured were within the field of view of the measurement system, a relative movement between the measurement system and the substrate would of course not be necessary.

[0004] The relative motion is usually performed by active motion of a substrate holder on which the substrate is fixed, so that no delicate optical systems have to be moved. In this case, the position of the substrate holder must be determined very accurately in order to be able to determine the distance traveled by the substrate holder, i.e. the position of the substrate holder must be expressed with respect to a spatially fixed coordinate system.

[0005] It is also possible to determine only the path traveled by the substrate holder between two points: in this case, the spatially fixed coordinate system is indeed omitted, but still, very sophisticated control devices are required to be able to determine the distance traveled very accurately.

[0006] The above-mentioned methods of the prior art require relatively expensive and complex electromechanical systems in order to be able to measure the position or path of the substrate holder and thus the structure position on the substrate surface of the substrate. Furthermore, the travel paths of such equipment are considerable. Due to the corresponding structure size, even the smallest temperature fluctuations have an effect on the thermal expansion of the components used and thus on the component size.

[0007] In order to bring the structurings on the substrate surface of the substrate into the field of view of the optical system one after the other, so that they can be measured, which are not simultaneously in the field of view of the optical system, a relative movement between the substrate and the optical system must be performed. In most cases, the optical system is fixed while the substrate holder, on which the substrate is fixed, moves. During the movement, the position of the substrate holder must be continuously tracked. This means that a reference system is required, with respect to which the position of the substrate holder is displayed. The position display of the substrate holder and thus of the substrate must be performed very precisely, in particular in the nanometer range. This precise position display, in particular over a path of several centimeters, requires very precise and therefore expensive measuring systems, in particular interferometers.

[0008] It is therefore the object of the invention to provide an apparatus and a method for measuring a substrate, which allows a more accurate and / or more efficient determination of the position of structuring or structural features on the substrate.

[0009] The above problem is solved by the features of claims 1, 8 and 9. Advantageous developments of the invention are described in the dependent claims. Any combination of at least two of the features described in the description, the claims and / or the drawings also falls within the scope of the invention. When indicating ranges of values, values ​​lying within the stated limits are also disclosed as limit values ​​and can be claimed in any combination.

[0010] The idea behind this invention is that Markfield - at least two location marks, each containing information about the location (orientation) of the location mark within the mark field; at least one position mark assigned or assignable to one of the location marks, which determines the XY-position (coordinates) of a structural feature of the structured part on the substrate, in particular independently of the movement or position of the substrate holder; The aim is to establish

[0011] The measurement according to the invention of the structured portion of the substrates allows in the subsequent process steps, in particular a more accurate and more efficient bonding process between the two substrates. If the measured structured portion position is not equal to the desired structured portion position, an adjustment of at least one of the two substrates is carried out, in particular before and / or during the bonding process. In other words, the substrate pair is preferably formed according to a selection criterion. In particular according to the invention, the location of the structured portion, in particular the rotational position, is determined from the two XY-positions or from other features of the location mark and / or the position mark.

[0012] Furthermore, the invention makes it possible to determine the expansion or deformation of the structuring from the two XY-positions or from other features of the location and / or position marks.

[0013] One, particularly independent, inventive aspect consists in associating or relating the individual XY-positions of the structural features of the structured part on the substrate surface of the substrate to position marks on the surface of the substrate facing away from the substrate surface, in particular determining their spacing in the X-direction and / or Y-direction. For this purpose, in addition to the position marks, particularly additional location marks are used. By using position marks and location marks of this kind, it is no longer necessary to determine or track the position of the substrate holder with high precision, in particular by means of technically complex or cost-intensive, in particular optical, measuring systems. A rough determination of the current position is performed in particular by reading and interpreting the location marks. A more precise determination of the current position can be performed in particular by means of additional, preferably assigned, position marks.

[0014] The invention thereby particularly describes a method and device for identifying, in particular measuring, preferably position measuring, structured or structural features without the need to determine the position of the substrate holder and thus the substrate relative to a (separate) reference system.

[0015] Another, and in particular independent, aspect of the invention is to provide a method and an apparatus which in particular makes it possible to completely omit the use of a spatially fixed reference system with respect to which the XY-position of the substrate holder is indicated or measured.

[0016] The basic idea is in particular to form a mark field on a surface which is preferably arranged or can be arranged such that it lies opposite the substrate surface on which the structuring or structural features are to be measured.

[0017] The mark field has two particular properties: each mark of the mark field is coded in such a way that the measuring system, in particular the optical system, can deduce the location of the mark. Once this location is known, the device can perform a highly accurate position determination, preferably by means of a position mark assigned to each location mark.

[0018] If the mark field is known and two mutually calibrated optical systems are used, then the structuring / structuring features of the substrate surface of the substrate to be measured can be related to the mark (and vice versa), which allows calculations, especially the calculation of the spacing changes, without the need for a spatially fixed external reference system.

[0019] A spatially fixed reference system, relative to which the position of the substrate holder has to be noted, is no longer required, i.e. it is no longer necessary to track the position of the substrate holder optically by means of an interferometer or mechanically by means of a step counter. Therefore, in a development of the invention, no means are used or the device is equipped with for detecting (in particular for keeping) the position of the substrate holder, apart from the means disclosed according to the invention, in particular as described below.

[0020] Another important aspect of the present invention is to reduce or substantially avoid distortion of the mark field and / or the position marks, among other things.

[0021] mark A mark is understood in the broadest sense in the present invention as an optically and / or topographically detectable structure (or structural feature of the structure), the structure (or structural feature of the structure) or its position, preferably at least its XY-position, can be detected and thus determined by a measuring device. Measuring devices for detecting the structure / structural feature and thus determining its position are in particular: -Optical systems, in particular cameras, - Contact systems, especially AFM, It may be.

[0022] The marking preferably consists of at least one of the materials described below: - Metals, especially Cr,Al,Ti,Cu,Ag,Au,Fe,Ni,Co,Pt,W,Pb,Ta,Zn,Sn, - Alloys, especially Metal alloys, metal-nonmetal alloys, -ceramic, -plastic, -Semiconductors, especially Compound semiconductors, especially GaAs,GaN,InP,InxGa1-xN,InSb,InAs,GaSb,AlN,InN,GaP,BeTe,ZnO,CuInGaSe2,ZnS,ZnSe,ZnTe,CdS,CdSe,CdTe ,Hg(1-x)Cd(x)Te,BeSe,HgS,AlxGa1-xAs,GaS,GaSe,GaTe,InS,InSe,InTe,CuInSe2,CuInS2,CuInGaS2,SiC,SiGe, Semiconductors, especially Ge, Si, α-Sn, fullerene, B, Se, Te.

[0023] Preferably, the marks are detected optically, so that in the following the optical measurement will be described. The marks consist in particular of location marks and position marks. The location marks are preferably according to the invention codable or coded marks, i.e. information carriers. The position marks are in particular used exclusively for determining highly accurate positions, in particular XY-positions.

[0024] In particular, the location marks and the position marks assigned to them are detectable simultaneously within the field of view of the optical system respectively used. Preferably, the location marks, in particular each location mark, are arranged relatively close to the assigned position mark so that simultaneous detection is guaranteed.

[0025] According to an advantageous embodiment of the invention, the location mark can comprise one or more position marks.

[0026] The location mark is in particular smaller than 5 mm x 5 mm, preferably smaller than 1 mm x 1 mm, more preferably smaller than 0.1 mm x 0.1 mm, especially preferably smaller than 0.01 mm x 0.01 mm, most preferably smaller than 0.001 mm x 0.001 mm. Particularly preferably, the location mark has a width or diameter of 20 μm to 200 μm.

[0027] The position marks are in particular smaller than 0.1 mm x 0.1 mm, preferably smaller than 0.01 mm x 0.01 mm, more preferably smaller than 0.001 mm x 0.001 mm, especially preferably smaller than 0.0001 mm x 0.0001 mm, most preferably smaller than 0.00001 mm x 0.00001 mm.

[0028] The location marks and / or position marks are preferably part of a pattern generated in a computer. The positions of the location marks and position marks in the digital pattern can be considered ideal. The location marks and position marks are produced, in particular by layering, masking, etching and developing techniques, resulting in real location marks and position marks. The positions of these real location marks and position marks deviate from the desired ideal positions, in particular based on processes and equipment that may involve errors. These deviations are preferably minimal and in the nanometer range. The accuracy of the location marks and position marks is therefore higher the smaller the deviation between the ideal position and the real position. The deviations are in particular smaller than 1 μm, preferably smaller than 500 nm, more preferably smaller than 250 nm, particularly preferably smaller than 50 nm, most preferably smaller than 10 nm.

[0029] Another aspect of the invention is to accommodate manufacturing imprecision of the mark field carrier, in particular of the marks, in particular of the position marks that should be produced with high precision, so that the device has a mark field, in particular with position marks that are not produced with high precision, whereby production costs can be significantly reduced.

[0030] Nevertheless, in order to be able to utilize position mark fields that provide highly accurate positions, the target position mark fields are stored and stored, in particular in a computer. The positions of the position marks in the computer can be considered ideal, while the actual positions (actual positions) of the created position mark fields may deviate therefrom. In the adjustment process, the mark field of the mark field carrier is measured (actual positions are determined) and the relative positions between the ideal position marks in the computer and the actual position marks on the mark field carrier are determined and stored.

[0031] From there, for each real position mark, a corresponding correction is calculated with respect to the ideal position mark, in particular in the form of a vector for the respective position. In this way, it is possible to correlate the structuring on the substrate with the real position marks on the mark field carrier, and the real position marks on the other hand with the ideal position marks in the computer. With this idea, the manufacturing costs of the mark field carrier are significantly reduced, in particular by allowing for a relatively inaccurate manufacturing of the mark field, thus resulting in economic advantages.

[0032] According to the invention, each location mark is individualized within the mark field. Due to the individualization, the possibility of confusing different location marks is eliminated, so that by detecting each location mark it is possible to deduce the XY-coordinate area of ​​the location mark on the mark field. The coordinate system of the mark field is in particular called the mark field coordinate system. The location marks preferably have the following characteristics: -QR code, - Barcode, -Geometric, especially three-dimensional figures, - symbol strings, in particular character and / or numeric strings, preferably binary codes, -image, One or more of the following:

[0033] The location marks are in particular information carriers. Preferably, each location mark is coded with an XY-position indicating in which position in a raster this location mark is located, i.e. in which XY-coordinate area this location mark is located.

[0034] The position marks can be constructed as simple or complex structures. The detailed shape of the position marks will not be described in detail, since it is known per se in the prior art. In the figures, the position marks are particularly shown as crosses. The position marks are preferably produced identically to the alignment marks customary in the prior art and preferably have the same appearance. This allows the techniques used for the analysis of alignment marks in the prior art to also be used for the analysis of the position marks.

[0035] In a particularly preferred embodiment according to the invention, the position mark surrounds, in particular encircles, the location mark, in which case the position mark is configured in particular as a circle, a rectangle, an octagon or any other geometrical figure that can be easily recognized and evaluated by software.

[0036] Mark Field The mark field consists in particular of a set of marks, namely location marks and position marks, which are preferably arranged highly symmetrically with respect to one another. What is important in the present invention is, inter alia, that the position marks are created with high accuracy with respect to one another. The location marks assigned or assignable to the position marks are arranged in such a way that both are preferably simultaneously present in the field of view of the optical system. The location marks are used in particular exclusively to read the approximate location position (orientation), which is observed by the optical system and which in the following text will only be called location. Preferably, the relative position between each location mark and the assigned position mark is the same. This makes it easier to program the evaluation algorithm and thus to search for the location marks and / or position marks in the mark field as soon as the location marks and / or position marks are present in the field of view of the optical system.

[0037] In one particularly preferred embodiment, the location mark is surrounded, in particular surrounded all around, by the position mark.

[0038] This allows the manufacturing precision of the location marks to be lower than that of the position marks, thereby minimizing the manufacturing costs for the mark field.

[0039] If the mark field is made up of location marks and position marks fused together, then preferably all marks in the mark field are produced with high precision, since each mark is both a location mark and a position mark, i.e. has both functions.

[0040] Preferably, the marks are arranged with uniform spacing between the location marks in any, particularly symmetrical raster. Adjacent location and / or position marks are preferably arranged with equal spacing on the mark field. In the mark field, in particular there are more than 10x10 marks, preferably more than 100x100 marks, more preferably more than 1000x1000 marks, especially preferably more than 10000x10000 marks, most preferably more than 100000x100000 marks. The spacing between adjacent location marks is in particular smaller than the width and / or height or diameter of the location marks. Preferably, the ratio of the spacing to the width and / or height or diameter of the location marks is smaller than 1, more preferably smaller than 0.5, even more preferably smaller than 0.1.

[0041] Preferably, the location marks code their XY-position within the raster, so that when detecting the location marks it is possible to deduce for the respective raster area that has just been detected by the detection means, in particular the optical system or systems. It is possible to code additional information within each location mark, for example the location of the assigned position mark relative to the location marks.

[0042] For the avoidance of doubt, the marks do not have to be on a highly symmetrical raster. The distribution of the marks can be arbitrary, as long as the spacing relationship (vector or XY-spacing) between the position marks is known and each location mark can be associated with its corresponding position mark. A distribution of marks on an asymmetrical raster represents a slightly degraded embodiment.

[0043] The mark field is preferably arranged as close as possible to the substrate surface on which the structure to be measured or the XY-position of which is determined according to the invention is located. On the other hand, the structures forming the mark field should be protected from damage. The distance between the structure to be measured and the mark field carrier is preferably 0.1 mm to 100 mm, preferably 0.25 mm to 75 mm, more preferably 0.5 mm to 50 mm, particularly preferably 1 mm to 30 mm, most preferably 5 mm to 20 mm.

[0044] In particular, the mark field is arranged on the side of the mark field carrier facing away from the substrate, so as to protect it from mechanical loads and wear, and is thus not in direct contact with the substrate. It is also possible for the mark field to be covered with a transparent coating to protect it from mechanical and / or chemical influences.

[0045] Mark Field Carrier A mark field carrier according to the invention is one or more components on which a mark field is / is provided.

[0046] According to a first embodiment of the invention, the substrate holder itself is the mark field carrier: the mark field is present on one of its two surfaces, preferably on the fixing surface on which the substrate is fixed.

[0047] If the mark field is present on the fixed surface, the substrate holder, at least below the mark field, is preferably made at least partially transparent for the electromagnetic radiation observing the mark field.

[0048] If the mark field is present on a surface located opposite the fixing surface, the substrate holder may be opaque.

[0049] In a second, particularly preferred embodiment according to the invention, the mark field carrier is an independent component, which can be fixed in or on the substrate holder and is thus quickly exchangeable.

[0050] Preferably, in this case too, the mark field is provided on a fixed surface, said component being at least partially transparent to the electromagnetic radiation used. With this configuration, the mark field carrier can be manufactured separately from the substrate holder. This increases flexibility and facilitates replacement. Furthermore, production costs can be reduced.

[0051] According to an extension of the invention, the substrate holder is configured in such a way that a mark field carrier can be inserted into it and is supported only at the periphery. In this particular embodiment, the mark field carrier is configured as thick as possible, so that the bending resistance is as high as possible and distortion of the position marks is minimized, preferably completely eliminated. The thinner the mark field carrier is, which is supported only at the periphery, the more it is curved by the force of gravity. The curvature leads to an extension of the mark field carrier surface facing the direction of gravity. The mark field is therefore also compressed, which reduces the accuracy of determining the XY-position.

[0052] According to another development according to the invention, the substrate holder is configured such that the mark field carrier can be inserted into the substrate holder and is supported from below not only at the periphery but also by pillars, in particular centrally-oriented pillars. The pillars in particular minimize the curvature of the mark field carrier. Preferably, the pillars are at least partially transparent to the electromagnetic radiation used in detecting the XY-position of the structuring. If the pillars are opaque, no correlation can be formed between the marks of the mark field and the structuring on the substrate surface along the planes hidden by the pillars.

[0053] The transmittance of the mark field carrier and / or the support is in particular higher than 10%, preferably higher than 25%, more preferably higher than 50%, especially preferably higher than 75% and most preferably higher than 95%.

[0054] The problem of bending can be addressed, inter alia, by making the mark field carrier as thick as possible, in particular with a thickness of more than 1 mm, preferably more than 2 mm, more preferably more than 5 mm, particularly preferably more than 20 mm, most preferably more than 30 mm. The thicker the mark field carrier, the greater its bending resistance and the less easily it is deformed by bending.

[0055] The substrate may have any arbitrary shape, but is preferably circular. The diameter of the substrate is especially industry standardized. For wafers, the industrially common diameters are 1 inch, 2 inches, 3 inches, 4 inches, 5 inches, 6 inches, 8 inches, 12 inches and 18 inches. However, embodiments according to the invention are in principle capable of handling any substrate, regardless of its diameter.

[0056] The mark field carrier and / or the mark field in particular have a diameter and / or a peripheral contour that is approximately equal to the diameter of the substrate.

[0057] In a particular embodiment, the diameter of the mark field carrier is larger than the diameter of the substrate, in particular larger than 1.01 times the diameter of the substrate, preferably larger than 1.05 times, more preferably larger than 1.1 times, especially preferably larger than 1.2 times, most preferably larger than 1.2 times.

[0058] According to one development of the invention, the support is as transparent as possible. Preferably, the support itself is manufactured from a material that is completely transparent to the electromagnetic radiation used. It is also possible to provide the support with grooves and holes as extensively as possible in order to provide as much visibility as possible for the optical system used. In order to improve the reduced support effect again, the grooves and holes can be closed by transparent inserts, in particular in a form-fitting manner and / or flush.

[0059] The mark field carrier is preferably at least partially made from at least one of the following materials: - Metals, especially Cu,Ag,Au,Al,Fe,Ni,Co,Pt,W,Cr,Pb,Ti,Ta,Zn,Sn and / or - Plastics, especially Elastomers, especially Viton (material) and / or Polyurethane and / or Hypalon (material) and / or Isoprene rubber (material) and / or Nitrile rubber (material) and / or Perfluororubber (material) and / or Polyisobutene (material), Thermoplastic elastomers and / or -semiconductor materials, especially Compound semiconductors, GaAs,GaN,InP,InxGa1-xN,InSb,InAs,GaSb,AlN,InN,GaP,BeTe,ZnO,CuInGaSe2,ZnS,ZnSe,ZnTe,CdS,CdSe,CdTe ,Hg(1-x)Cd(x)Te,BeSe,HgS,AlxGa1-xAs,GaS,GaSe,GaTe,InS,InSe,InTe,CuInSe2,CuInS2,CuInGaS2,SiC,SiGe, Semiconductors, especially Ge, Si, α-Sn, fullerene, B, Se, Te, - Glass, especially Metallic glass, Non-metallic glasses, especially Organic non-metallic glasses, Inorganic non-metallic glasses, especially Non-oxide glasses, especially Halide glasses, Chalcogenide glasses, Oxide glasses, especially Phosphate glass, Silicate glasses, especially Aluminosilicate glass, Lead silicate glass, Alkali silicate glasses, especially Alkali-alkaline earth silicate glasses, Borosilicate glass, Borate glasses, especially Alkaline borate glass, quartz, -ceramic, -Minerals, especially sapphire.

[0060] The mark field carrier is preferably -Cylindrical, - (preferably) rectangular parallelepiped, However, the mark field carrier can in principle take any arbitrary shape.

[0061] The mark field carrier is preferably manufactured from a material that has a very low coefficient of thermal expansion so that temperature fluctuations do not lead to distortion of the mark field carrier and thus the mark field.

[0062] If the mark field carrier is made of a material with a not very low coefficient of thermal expansion, it is preferably mounted in such a way that the expansion of the mark field surface is prevented, i.e. the mark field surface cannot expand despite possible temperature fluctuations or deviations. This condition is solved in terms of construction technology, in particular by mounting the mark field carrier in a component, in particular a substrate holder, which itself consists of a material with a low coefficient of thermal expansion.

[0063] It is desirable for the coefficient of thermal expansion of the mark field carrier to be as small as possible in order to prevent distortion of the mark field carrier due to temperature differences or distortion of components that impede the expansion of the mark field carrier. -4 K -1 Smaller, preferably 5 x 10 -5 K -1 Smaller, more preferably 10 -5 K -1 Smaller, particularly preferably 5×10 -6 K -1 Smaller, particularly preferably 10 -6 K -1 Less than 10, most preferably -7 K -1 Less than.

[0064] The mark field is preferably arranged on the mark field carrier as close as possible to the structured portion of the substrate to be measured, if the mark field carrier is in contact with the substrate to be measured. By appropriately minimizing the distance between the mark field and the structured portion to be measured, possible optical errors that may arise due to the alignment of the optical axes of the optical systems that are calibrated to one another are minimized.

[0065] In embodiments in which the mark field carrier and the substrate holder are different components or groups, the fixing elements may be present on the substrate holder and / or on the mark field carrier, if the fixing elements are present on the mark field carrier, a control connection is preferably provided between the substrate holder and the mark field carrier for controlling the fixing elements on the mark field carrier.

[0066] The fixing elements are used to hold the substrate. The fixing elements may be any of the following fixing elements: - mechanical fastening means, in particular clamps; vacuum fixing means, in particular vacuum fixing means having a number of vacuum strips which can be individually controlled or which are connected to one another, - Electrical fastening means, in particular electrostatic fastening means; - magnetic fastening means, adhesive fastening means, in particular Gel-Pak fastening means, - fastening means having an adhesive, in particular a motion-controllable surface, It may be one or more of:

[0067] The clamping means are controllable, in particular electronically. Vacuum clamping is a preferred form of clamping. The vacuum clamping preferably consists of a number of vacuum paths, which are exposed to the surface of the sample holder. The vacuum paths are preferably individually controllable. In a technically more feasible application, several vacuum paths are grouped together in vacuum path segments, which are individually controllable and thus can be evacuated or pumped independently of one another. The vacuum path segments are preferably configured in the shape of a ring.

[0068] A special form of clamping is realized by a low contact substrate holder, which consists of a number of individual, in particular symmetrically distributed, raised pins. This substrate holder is also called a pin chuck. The space between the raised pins can be evacuated and thus serves at the same time as a vacuum clamping. Advantageously, only the raised pins come into contact with the substrate, and thus relatively little stress and contamination is required on the side of the substrate to be clamped. A further advantage is that with a low contact substrate holder the clamped substrate needs to be distorted as little as possible, which is an advantage for the measurement of structuring of the substrate. A further advantage is that the low contact substrate holder allows a largely uniform clamping of the substrate. An embodiment of such a substrate holder is disclosed in WO 2015 / 113641, to which reference is made in this respect. Such low-contact substrate holders are preferably at least largely opaque so that the mark field according to the present invention resides on a surface spaced from the substrate fixing surface.

[0069] In another, less preferred embodiment according to the invention, the substrate on which the structure to be measured is present is itself the mark field carrier. The mark field is arranged on the substrate surface located opposite to the substrate surface with the structure to be measured. This unpreferred embodiment has the following disadvantages: Firstly, a mark field has to be produced for each substrate, which leads to additional effort and costs. Secondly, producing a structure on one side of the substrate and a mark on the other side of the substrate leads to production problems and possibly distortions. Thirdly, substrates usually have a low bending resistance, which can also lead to distortions of the mark field.

[0070] It is therefore advantageous according to one development of the invention to have the mark field preferably clearly separated from the substrate to be examined, ie the mark field is not arranged on the substrate itself.

[0071] Device The device according to the invention consists of a mark field carrier, a substrate holder and at least two optical systems. The mark field carrier is preferably part of the substrate holder (and vice versa). Insofar as the present specification speaks of the substrate holder or the mark field carrier, these are considered as a unit or are used synonymously.

[0072] Both optical systems are constructed and arranged facing each other. The optical axes of both optical systems are preferably as well calibrated to each other as possible, and are preferably oriented parallel or aligned. For the calibration of two optical systems oriented to each other, see WO 2014 / 202106. The optical systems are translatable in the x-direction and / or the y-direction and / or the z-direction and / or rotatable about three spatial axes, each preferably arranged perpendicular to each other. These degrees of freedom are used for the calibration of the optical systems. Once both optical systems are calibrated to each other, preferably no relative movements between the optical systems are performed anymore. The optical systems are fixed relative to each other during the inventive determination of the XY-position.

[0073] Just to be sure, the possibility of coupled movement of two optical systems calibrated to each other is disclosed. Preferably, the optical systems are mechanically coupled to each other via a kind of U-shaped coupling, so that they are also fixed relative to each other during the inventive determination of the XY-position. However, it is more preferable to mechanically decouple both optical systems from each other. Preferably, the optical systems are mechanically decoupled as best as possible or at least cushioned from the frame or surface over which the substrate holder is moved in order to minimize vibrations.

[0074] The frame is preferably mechanically decoupled or at least cushioned from the optics to avoid vibration transmission as completely as possible.

[0075] method Prior to the decisive method step according to the invention of determining the XY-position, both optical systems are in particular calibrated as best as possible to one another.

[0076] The optimal calibration method is to orient the optical axes of both optical systems so that they are congruent, i.e. coincident, with each other. Reaching this state can be technically difficult or even impossible, but preferably one should at least try to get as close to this state as possible.

[0077] Another important step for optimal calibration of the two optical systems with respect to each other is to overlap the depth of field ranges of the two optical systems, so that the crossing range of the depth of field ranges allows simultaneous detection of the mark field and the structure to be measured. This is only possible if the two depth of field ranges are at least the same as or larger than the distance between the mark field and the structure to be measured, which is hereby disclosed as an advantageous embodiment of the invention. In particular in the case of thick substrates or in the case of mark field carriers in which the mark field is located far away from the structure to be measured, the mark field is focused by one optical system and the structure by the other optical system, i.e. brought into the respective depth of field ranges of the respective optical systems.

[0078] Prior to the method according to the invention itself, preferably both optical systems are calibrated against each other so that possible errors that may occur due to the skew of both axes can be taken into account when determining the XY-position. Preference is given in the present invention to the production of a mark field carrier with a mark field that can be used as versatile as possible for any type of structuring of any substrate. This is desirable, in particular in view of the high production costs required for such mark field carriers. Preference is given hereto to a mark field that is produced as independently as possible of the structuring of the substrate to be detected.

[0079] In a special embodiment according to the invention, several position marks may be assigned to one location mark, resulting in a very dense field of position marks. Alternatively or additionally, several position marks are arranged in the field of view of the optical system. The field of view is preferably rectangular, most preferably square, i.e. the number of pixels per unit dimension of the field of view is constant. The number of position marks per unit dimension of the field of view is then at least 1, preferably more than 3, more preferably more than 5, particularly preferably more than 7, most preferably more than 10. The numerous position marks according to the invention ensure that at least one (preferably at least two) position marks are always found in the field of view, even if the next location mark is not yet visible. The density of the position marks may therefore be in particular higher than the density of the location marks. The density of the position marks is the same as the density of the location marks, preferably twice the density of the location marks, more preferably five times, particularly preferably ten times, most preferably 100 times.

[0080] In particular, the method according to the invention and the embodiment in which several position marks are simultaneously present in the field of view allow for an averaging of the position marks, preferably compensating for manufacturing errors of the position marks. The averaging results in correspondingly averaged virtual position marks, which can then be used as position marks for measuring structuring on the substrate surface. It is assumed that four position marks are simultaneously present in the field of view, all of which are located at the corners of a square. By determining the positions of the position marks, the center of the square can be calculated, which is used as the new position mark. This new position mark does not actually exist physically, but can also be determined by a computer, stored and, if necessary, written into the digital image. It is not important for the method according to the invention whether physically existing position marks or calculated position marks are used for the method according to the invention.

[0081] The method according to the invention can in particular be used to determine deviations between actual and target parameters of a structuring on the substrate surface or of at least one structural feature of the structuring, i.e. in particular production errors. Possible production errors are that a photolithography process may carry out a slightly oblique exposure, that an etching process may lead to poor edge quality, etc. Furthermore, deviations may also be subsequent distortions, in particular distortions due to temperature fluctuations. In particular, the structuring may be -Rotational errors and / or - Translation errors and / or -Scaling errors and / or -Residual error The structure may have a rotation error, which is understood as an error in which the structure rotates, globally and / or locally, with respect to its ideal target position. The translation error, which is understood as an error in which the structure translates, globally and / or locally, with respect to its ideal target position. The scaling error, which is understood as an error in which the structure is scaled, globally and / or locally, with respect to its ideal target position. This error is also called "runout" in the world of the person skilled in the art. "Runout" is characterized in particular by an increase in the error as the radius increases. In most cases, this error is the result of thermal expansion, which acts more strongly at the edge of the substrate than in the region near the center. Residual error refers to all other types of errors that lead to a deviation between the target structure and the actual structure. The effect of the actual structure differing slightly from the target structure is referred to below as an initial error or "incoming error".

[0082] Further or additional errors may occur during subsequent processes, in particular during the bonding process. The embodiment according to the invention is particularly suitable for measuring the structure before further processes, in particular before the bonding process. The measurement of the actual state of the structure, in particular immediately before the bonding process, is of fundamental importance in order to guarantee and ensure the conformity of the structure of the two substrates to be bonded. However, it should be mentioned that it is also possible to carry out a measurement of the structure related to the mark field according to the invention after the bonding process has been carried out by the method according to the invention. For this purpose, the substrate through which the structure is to be examined must be transparent to the electromagnetic radiation used in each case in order to be able to recognize the structure in the bonding interface. It is also possible to use a glass substrate. It is also possible that the corresponding substrate is transparent to infrared radiation, and infrared radiation can be used for the measurement of the structure. It is also possible to design the substrate thin enough that it is sufficiently transparent to visible light. For silicon this is the case when the thickness is less than 10 μm, preferably less than 5 μm, more preferably less than 3 μm, especially preferably less than 2 μm, most preferably less than 1 μm.

[0083] Therefore, as an independent invention, the present invention also discloses a method for identifying the XY-positions of structured parts / features of two substrates which are to be connected in a subsequent bonding step.

[0084] In an optional method step, the optical axes of the two optical systems used are calibrated with respect to each other. Calibration of both optical systems is preferably performed by means of a calibration substrate.

[0085] The calibration substrate has a thickness that is approximately equal to the distance between the structured portion to be measured on the substrate and the mark field. The calibration substrate has two calibration marks, one on each side. The two calibration marks must be correlated with one another as best as possible, i.e. they must be directly superimposed. In other words, the lateral displacement between the two calibration marks should be minimal. In a particularly preferred embodiment according to the invention, a calibration mark of this kind is produced by forming a through-hole, in particular a through-hole or even more preferably a through-etching, from one substrate surface to the other. The holes in the substrate surfaces then coincide with one another over the thickness. This method is referred to below as the drilling method. In a first calibration method according to the invention, the upper optical system focuses on the upper calibration mark and the lower optical system focuses on the lower calibration mark. The optical axes of the two optical systems generally do not coincide with one another, so that the calibration marks merged in one image do not coincide either. The distances dx1 and dy1 in the x and y directions between the calibration marks are measured and stored.

[0086] The substrate is then rotated 180° and the calibration marks are measured again. The distances dx2 and dy2 between the calibration marks in the x and y directions are measured and stored.

[0087] In a further calibration step, the error values ​​dx and dy are calculated: dx=dx1+dx2 dy=dy1+dy2 The values ​​dx and dy thus obtained are thus the (double) total error, consisting of the (double) lateral displacement of the calibration mark and the (double) optical error: dx = (2x) lateral displacement x + (2x) optical error x dy = (2x) lateral displacement y + (2x) optical error y By using the already mentioned optimum construction methods for the calibration marks, in particular the drilling method, the lateral displacements can be reduced practically to zero, the values ​​dx and dy representing the (double) optical errors: (2x) optical error x=dx (2x) optical error y=dy If the lateral displacements are not small enough, then the lateral displacements must be determined in a different way and then subtracted: (2x) optical error x = dx - (2x) measured lateral displacement x (2x) optical error y = dy - (2x) measured lateral displacement y The optical errors in the x and y directions ultimately Optical error x = (2x) optical error x / 2 Optical error y = (2x) optical error y / 2 The optical errors in the x and y directions need only be calculated once, as long as the optical systems are not subsequently moved further relative to one another. They can then be used to correct the measured x and y spacings between the structure on the substrate surface and the corresponding position marks in the mark field by the optical errors. The optical errors are preferably stored as vectors and are denoted by the letter F in the following text.

[0088] In a further method step according to the invention, the substrate is fixed to the substrate holder and to the mark field carrier with the mark field. Preferably, the substrate and the mark field carrier are two separate components. In particular, the substrate is fixed directly to the mark field carrier, which in turn is fixed to the substrate holder.

[0089] In a subsequent method step according to the invention, the structured features on the substrate surface, in particular all the structured features, are moved and measured. A first, in particular an upper optical system, views the structured features of the substrate, while a second, in particular a lower optical system, views a corresponding area of ​​the mark field with at least one location mark and at least one position mark. Both generated images can be digitally superimposed, thus resulting in a superimposed image that can be evaluated preferably digitally by software.

[0090] As soon as the location mark is located within the field of view of the lower optics, information about the XY-coordinate field of the location mark is evaluated. As a result, the device now knows in which rough position the substrate holder and thus the substrate are in relative to the optics. Preferably, the position mark is centered relative to the lower optics, so that it is in the center of the field of view of the optics. Alternatively, the optics can be centered relative to a characteristic structural feature of the structured part to be measured. Preferably, the position mark is centered, since a number of characteristic structural features of the structured part should be measured relative to the position mark, so that the rotational position of the structured part can also be determined.

[0091] Centering of the position mark, although preferred, is not essential to the practice of the invention since absolute positioning is not required when measuring the distance between the position mark and the distinctive structural feature of the structured portion.

[0092] It is important that at least one characteristic structural feature of the structure is measured relative to the position mark. For example, in the case of a rectangular structure, the upper left corner can be selected. In the case of a rectangular structure, it is preferable to measure all four corners relative to the position mark. Measuring is understood to mean determining at least two values, namely the horizontal distance dx and the vertical distance dy, each relative to the same position mark.

[0093] In particular the image and / or the determined data, in particular the location data of the location marks and the position data of the position marks and the structures or structure features, are stored in a computer. This method step is carried out for any number, preferably for all, of the structures on the substrate.

[0094] In a further method step according to the invention, after obtaining the XY-position data of the detected, in particular all characteristic, structural features of the structure, the determined XY-positions are determined with respect to the respective ideal (target) positions. In particular, an ideal structure, preferably a mark field, is suitable as a reference. This allows the deviation of the characteristic structural features, i.e. the difference between the target state and the actual state, to be determined.

[0095] The precise, in particular mathematical, determination of the XY-position or deviation is carried out in particular taking into account one or more of the following points: - The axes of the mark field are not aligned with the axes of the substrate coordinate system. The ideal position marks of the mark field in the computer are not arranged the same as the real position marks of the mark field on the mark field carrier. The deviation can be measured and stored. The correlation between the positions of the real position marks in the mark field and the positions of the real structuring on the substrate can be determined as described herein. - Ideal position of the mark field in the computer The correlation between the position of the mark and the ideal position of the structuring part in the computer can be calculated since the data is always provided and does not have to be measured first. -Optical errors can be calculated from the data using values ​​determined in a calibration process. The data from the above enumeration always allows the calculation of the deviation of the real structuring on the substrate from the ideal structuring in the computer.

[0096] In one process step, the axial orientation of the mark field coordinate system relative to the substrate coordinate system is determined, in particular the correction is performed by a relative displacement between the substrate and the mark field carrier, in particular an active movement of the substrate.

[0097] However, since it is not advantageous to move the substrate again after it has been fixed to the mark field carrier, the correlation between the coordinate systems is determined in particular mathematically. By measuring a number of position marks on the mark field carrier, in particular along two mutually perpendicular directions, the directions of the axes can be determined.

[0098] A similar idea applies to the axes of the substrate. From these data, a rotation matrix R is calculated. The displacement between the two coordinate origins is represented in particular by the vector v. This shows that a correction term for the correlation between the position marks on the mark field carrier and the structuring on the substrate is added to the equation x 基板 =R×x マークフィールド +v. The corresponding inverse notation is x マークフィールド =R -1 x 基板 -v. Those skilled in the art have the necessary matrix algebra knowledge.

[0099] Since for this process step several position marks of the mark field or several structurings on the substrate are measured, this process step cannot be clearly assigned in time without problems. The correlation between both coordinate systems can be performed more accurately the more data there is. Preferably, a mathematical algorithm based on the least squares method is used to determine the rotation matrix and the displacement vector. In the following text, it is assumed that the axis orientations of all coordinate systems involved always have the same origin and the same orientation with respect to each other.

[0100] The following convention is used to explain the mathematical calculation process: index i stands for ideal, index r stands for real, index S stands for structure, and index M stands for mark. Dissimilarity vectors are always denoted with a lowercase r. Dissimilarity vectors are calculated in particular from position vectors pointing to end points, and rarely from position vectors pointing to start points. Correspondingly, as is the mathematical convention, the index of the end point is listed first. Position vectors are shown far below and are not included in the figures described. As an example, vector r to be calculated according to the invention is Sr,Si This is a discrepancy vector that represents the deviation in position between the real structuring and the ideal structuring.

[0101] In a further process step, the positions of the ideal position marks in the mark field in the computer are compared with the positions of the real position marks in the mark field on the mark field carrier. This measurement results in a table in which the real positions of the position marks and / or the ideal positions of the position marks and / or their difference vectors are stored in the computer. These difference vectors are calculated using the following formula: Mr,Mi The discrepancy vectors thus obtained yield a vector map, which in the following text will be referred to as the mark field error vector map.

[0102] In a further process step, the positions of the real position marks of the mark field on the mark field carrier are compared with the positions of the structures on the substrate. By measuring the real positions of the position marks of the mark field and the positions of the structures on the substrate, a table is obtained in which the real positions of the position marks and / or the positions of the structures on the substrate and / or the difference vectors are stored in a computer. These difference vectors are calculated based on the following formula: Sr,MrThe difference thus determined results in a vector map, which in the following text is called the actual mark structure difference vector map, which is the process step that forms the core idea of ​​the present invention, namely the association of the position marks of the mark field carrier with the structure of the substrate.

[0103] In a further process step, the positions of the ideal position marks of the mark field in the computer are compared with the ideal positions of the structuring part in the computer. By reading the ideal positions of the position marks of the mark field in the computer and the ideal positions of the structuring part in the computer, a table is obtained in the computer in which the ideal positions of the position marks in the computer and / or the ideal positions of the structuring part in the computer and / or the difference vectors are stored. These difference vectors are calculated by the following formula: Si,Mi The difference thus determined produces a vector map, which in the following text is referred to as the ideal mark structure difference vector map. In particular, this process step needs to be performed only once for each combination of ideal mark field and ideal structure field.

[0104] As a result, Sr,Si =r Mr,Mi +r Sr,Mr -r Si,Mi -F is produced, where F is the optical error vector calculated in the calibration process. Preferably, F is constant for all points, i.e., F represents a constant as a function of location, rather than a vector field.

[0105] Multiple measurements are possible according to the invention in order to improve the quality of the measurements by statistical averaging. A new measurement can be performed quickly with the existing data and the location of the location marks. The detection proceeds fastest if it is performed step by step from mark to mark. This makes it unnecessary to use a measurement system that specifically continuously tracks the absolute position of the substrate holder or the relative displacement of the substrate holder.

[0106] In an optional, but particularly desirable, further method step according to the invention, a rotation of the substrate, in particular a rotation of exactly 180°, is carried out in order to measure all previously measured structures anew. The finding of the structures can be carried out quickly, since they are already associated with the position-coded location marks in the previous detection step. By using an algorithm, possible optical errors caused by possible obliqueness of the optical axis of the optical system can be corrected.

[0107] All technically possible combinations and / or permutations and intermixtures of the functional and / or material parts of the apparatus and associated changes in at least one of the method steps or methods are considered to be disclosed.

[0108] To the extent that apparatus features are disclosed herein and / or in the following description of the drawings, the apparatus features should also be considered to be disclosed as method features, and vice versa.

[0109] Further advantages, features and details of the invention can be seen from the following description of preferred embodiments, taken in conjunction with the drawings. [Brief description of the drawings]

[0110] [Figure 1a] FIG. 2 is a detailed view of a first embodiment of a mark according to the invention comprising a location mark and a position mark. [Figure 1b]FIG. 2 shows a detailed view of a second embodiment of a mark according to the invention comprising a location mark and a position mark. [Diagram 2] 2A and 2B show a plan view and a cross-sectional view along the section line AA of an embodiment of a mark field carrier according to the invention having a mark field; [Diagram 3] 1A and 1B are a plan view and a cross-sectional view taken along line AA of one embodiment (first embodiment) of a substrate holder according to the present invention. [Figure 4] 2A and 2B are a plan view and a cross-sectional view taken along line AA of an embodiment (second embodiment) of a substrate holder according to the present invention. [Diagram 5] 2A and 2B are a plan view and a cross-sectional view taken along line AA of an embodiment (third embodiment) of a substrate holder according to the present invention. [Figure 6] 2A and 2B are a plan view and a cross-sectional view taken along line AA of an embodiment (fourth embodiment) of a substrate holder according to the present invention. [Figure 7] 1 shows a plan view and a cross-sectional view of a substrate according to the invention with a structuring and a mark field; [Figure 8] 1 shows a cross-sectional side view of an embodiment of the device according to the invention during a method step of detection according to the invention; [Figure 9] FIG. 13 is a partial side view of the detection step. [Figure 10] FIG. 13 is a partial side view of the detection step. [Figure 11] FIG. 13 is a partial side view of the detection step. [Figure 12] FIG. 13 is a partial side view of the detection step. [Figure 13] FIG. 13 is a partial side view of the detection step. [Figure 14a] FIG. 2 shows a superimposed image generated from the detection step at a first rotational position in a first position. [Figure 14b] FIG. 13 shows a superimposed image generated from the detection step at a second rotational position in the first position. [Figure 15a]FIG. 13 shows a superimposed image generated from the detection step at a first rotational position in a second position. [Figure 15b] FIG. 13 shows a superimposed image generated from the detection step at a second rotational position in a second position. [Figure 16] FIG. 2 shows a vector field generated according to the present invention to illustrate the deviations determined according to the present invention. [Figure 17] FIG. 13 shows the resulting discrepancy vectors.

[0111] In the drawings, the same components or components having the same functions are given the same reference numerals.

[0112] 1a shows a mark 1, which consists of a location mark 2, in particular a QR code, and a position mark 3. In a particularly preferred embodiment according to the invention, the location mark 2 is also used as a position mark, so that the position mark 3 is omitted and included in the location mark 2.

[0113] The location mark 2 is constructed so that the information can be read by any system, in particular an optical system. The exemplary QR code contains readable position information (1,11), from which it can be seen that this location mark is located in the first row, eleventh column of the grid of the mark field 4 shown in FIG. 2.

[0114] FIG. 1b shows a particularly preferred mark 1′, which consists of a location mark 2, in particular a QR code, and a position mark 3′. In this particular embodiment, the location mark 2 is smaller than the position mark 3′ and is surrounded in particular all around by the position mark 3′. The evaluation algorithm can recognize the shape or the contour of the position mark 3′ and determine the exact position of the position mark 3′. In the concrete case, the exact position is the center of an octagon. The center of the octagon can be found, for example, by the software, in that an algorithm fits a mathematical octagon to the contour of the octagon obtained from the measured image and determines the center from this mathematical octagon. Algorithms of this kind are known to the person skilled in the art and will not be described further here.

[0115] In the following description of the drawings, the mark 1 shown in FIG. 1a is used as an example to further explain the concept according to the present invention.

[0116] 2 shows a plan view and a side view of a mark field carrier 5 with a mark field 4, which consists of a plurality of marks 1 arranged, in particular highly symmetrically with respect to one another. The mark 1 shown in FIG. 1a is located in the first row and eleventh column with respect to the illustrated origin of the coordinate system 6 for the mark field carrier 5, and is therefore located at grid position (1,11). Counting here starts with zero.

[0117] The mark field 4 is preferably present on a mark field carrier surface 5o of the mark field carrier 5. The mark field carrier 5 is preferably transparent so that the mark field 4 is detectable through the mark field carrier 5 from the mark field carrier back side 5r. The mark field carrier 5 preferably has fastening means 12 to which a substrate 7 (see FIG. 8) can be fastened, the fastening means 12 being preferably formed in the form of a vacuum channel.

[0118] 3 shows a first embodiment of a substrate holder 8, in particular a transparent substrate holder 8, which is simultaneously formed as a mark field carrier 5. In this case, the mark field 4 is preferably present on the substrate holder surface 8o as well as the fastening means 12. In a further preferred embodiment according to the invention, the substrate holder 8 is opaque and the mark field 4 is arranged on the substrate holder rear side 8r.

[0119] FIG. 4 shows a second embodiment of a substrate holder 8′. The substrate holder 8′ accommodates the mark field carrier 5, i.e. the substrate holder 8′ is not a mark field carrier itself in contrast to the first embodiment. The mark field carrier 5 is preferably transparent. The mark field 4 is present on the mark field carrier surface 5o as are the fixing means 12. The mark field carrier 5 is not supported in the middle and can therefore bend downwards, in particular due to gravity, but also due to forces acting from above. A bending of this kind should preferably be reduced, since it can compress the mark field 4 on the mark field carrier surface 5o. This is achieved by configuring the mark field carrier 5 to be particularly thick.

[0120] Figure 5 shows a third further improved embodiment of the substrate holder 8''. The substrate holder 8'' has posts 10 which support the mark field carrier 5, so that bending is largely avoided. Preferably, the posts 10 are themselves transparent.

[0121] FIG. 6 shows a fourth further improved embodiment of the substrate holder 8'''. The substrate holder 8''' has a post 10 with a through-hole 14, which in particular extends tapered. In the through-hole 14 an individual mark field carrier 5', in particular formed as an insert, can be accommodated or is fixed, which mark field carrier 5' has a mark field 4. The fixing means 12 are present in this special embodiment, for example, in the substrate holder 8'''.

[0122] In particular, since only the pillars 10 have the mark fields 4, no marks are provided in the free areas between the pillars 10. This allows the substrate holder 8''' to be made extremely fine, lightweight and easy to manufacture. The substrate holder 8''' has a high rigidity despite its relatively small thickness. Furthermore, the mark field carrier 5' and thus the mark fields 4 can be replaced relatively easily.

[0123] FIG. 7 shows a fifth, less preferred embodiment of the mark field carrier 5'', which is here formed by the substrate 7 itself. The substrate 7 has a structure 11 on one side (the mark field carrier back side 5r'') and the mark field 4 on the opposite side. This special embodiment only makes sense if it can be ensured that the mark field carrier back side 5r'', on which the mark field 4 is present, is not deformed.

[0124] FIG. 8 shows a substrate holder 8 ′ with a mounted and fixed transparent mark field carrier 5 , on which a substrate 7 with a structuring 11 is fixed by fixing means 12 .

[0125] A first, in particular upper, optical system 13 detects with a field of view (shown enlarged) a substrate surface 7o on which a structure 11 is arranged. The first optical system 13 is focused on the structure 11.

[0126] A second optical system 13', specially calibrated with the first optical system 13 and preferably congruent with it, detects the mark field carrier surface 5o with the mark field 4 through the transparent mark field carrier 5. The second optical system 13' is focused on the mark 2.

[0127] The detected images are superimposed, in particular digitally superimposed, to produce one superimposed image from which the distances dx and dy between one (or more) structural features 11c (here the upper left corner of the structured portion 11) and a highly accurate position mark 3 are determined in relation to the XY-coordinate system.

[0128] 8, the corners (structural features 11c) of the structure 11 are not aligned with the position mark 3 and the distances dx and dy are therefore non-zero. Furthermore, the structure 11 is slightly rotated with respect to the reference alignment of the position mark 3.

[0129] From the field of view or the superimposed image of the optical system 13, 13', the location mark 2 is furthermore visible, which allows providing information about the rough position.

[0130] From detection of multiple structural features 11c, the rotational state and / or deformation of structured portion 11 can be determined.

[0131] 9 to 13 show further detection steps in different cases which are distinguished as follows:

[0132] FIG. 9: The optical axes of both optical systems 13 are coincident with one another. Furthermore, the characteristic structural features 11c of the structuring 11 are located directly above the position marks 3 which are important for the position measurement. This results in an ideal superimposed image. A further feature is that the density of the structuring 11 on the substrate surface 7o is equal to the density of the position marks 3 on the mark field carrier surface 5o. Preferably, a usable mark field carrier 5 is constructed for various substrates 7 with respectively different densities of the structuring 11.

[0133] The density of the marks 1 is in accordance with the invention in particular higher than the density of the structure 11. This ensures that at least one mark 1 in the area of ​​the structure 11 and / or the structural feature 11c is located within the field of view of the optical system 13, 13'.

[0134] FIG. 10: The optical axes of both optical systems 13 are coincident with one another. In this case, the characteristic feature 11c of the structure 11 is not located directly above the position mark 3 which is important for the position measurement. Any discrepancies occurring in the superimposed image are solely attributable to a misalignment between the position mark 3 and the structure 11 and are not due to optical errors. A further feature is that the density of the structure 11 on the substrate surface 7o is not equal to the density of the position marks 3 on the mark field carrier surface 5o.

[0135] It can also be seen from this figure that translational offsets do indeed exist between the structure 11, more precisely between the characteristic features 11c of the structure 11, and the position marks 3, but that these are the same for all (shown) superimposed images. This is equivalent to the fact that, to obtain the superimposition state shown in Fig. 9, it is only necessary to displace the substrate 7 relative to the mark field carrier 5 (naturally only for every other structure 11, since the density of the structure in Fig. 10 is only half that in Fig. 9).

[0136] FIG. 11: The optical axes of both optical systems 13, 13' are not coincident with each other, nor even parallel to each other. It cannot therefore be assumed that the characteristic structural features 11c of the structure 11 coincide in the superimposed image with the respective position marks 3 (even if they are exactly positioned on top of each other). The skew of the optical axis, as well as variations in the thickness of the substrate 7, wedge errors of the substrate 7, etc., lead to non-ideal superimposed images even under ideal conditions. To correct these optical errors, a second measurement of all the structures is carried out by performing a rotation of 180° (as described above) and the optical errors mainly due to the skew of the optical axis are calculated from the average value of the positions thus determined of the characteristic structural features 11c of the structure 11.

[0137] Figure 12: The density of the structuring 11 is different from that of the position marks 3. The characteristic structural features 11c do not coincide with the position marks 3 and the optical axes of the optical systems 3 do not coincide or are parallel to each other. By eliminating the errors due to the optical axes as explained with respect to figure 11, we are left with the superimposed image shown in figure 10.

[0138] FIG. 13: This embodiment shows a preferred case according to the invention. Again, the densities of the structured areas 11 and the position marks 3 are different. Due to the oblique optical axis, optical errors occur in the superimposed image. The optical errors are calculated by a rotation of 180° and a second complete measurement of all the structured areas. Furthermore, the structured areas 11 are shifted significantly to the left. The surface may have been distorted by certain processes and / or this part may have a stronger thermal expansion due to thermal loading. This displacement of the structured areas 11 is therefore no longer related to the overall displacement of all the structured areas 11 relative to the mark field 4, which is due in particular to the displacement of the substrate 7 as a whole relative to the mark field 4. This displacement of the structured areas 11 is location-specific and inherent. It is important, among other things, that the underlying mark field 4 is highly symmetrical and that this high symmetry is maintained.

[0139] The following figures are used to further explain possible error causes and the countermeasures taken with respect to these in the method according to the invention, so that they can be determined and evaluated when identifying them.

[0140] 14a shows a superimposed image of the structured portion 11 with the position mark 3 and the location mark 2 at a rotational position of 0° at position (11,1). The distance dx(11,1), 0° and dy(11,1), 0° between the position mark 3 and the characteristic structural feature 11c of the structured portion 11 are detected.

[0141] 14b shows a superimposed image of the structured portion 11 with the position mark 3 and the location mark 2 at a rotational position of 180° in a first position (11,1). The distance dx(11,1), 180° and dy(11,1), 180° between the position mark 3 and the characteristic structural feature 11c of the structure 11 are detected.

[0142] From the values ​​dx(11,1),0° and dx(11,1),180° or from the values ​​dy(11,1),0° and dy(11,1),180°, the errors caused by the skew of the optical axis and other error sources can be calculated in the x or y direction, so that the net deviation between the position mark 3 and the characteristic feature 11c of the structured portion 11 can be determined (calculated).

[0143] Figures 15a and 15b show another structure 11 in a second position (12,1), again in two different rotational positions (0° and 180°). Here too, the errors caused by the skew of the optical axis and other error sources can be calculated in the x- or y-direction. Figures 14 and 15 make it clear that the horizontal and / or vertical offset between the position mark 3 and the characteristic structure feature 11c can differ significantly in the different positions. These differences are the result, inter alia, of distortions, expansions, etc.

[0144] Fig. 16 shows the vector field. This vector field shows, in a schematic way, how the structure 11 (not shown here) is deformed as a function of location. The size of the arrows shows the increasing deformation from the center outwards. This shows, in a schematic way, that the structure is stretched towards the edge of the substrate 7. The length of the arrows is increasing. This shows, in a schematic way, that the translational deviation is magnified towards the edge. That is, this is a classic run-out error. Since none of the arrows have a tangential component, no rotational deviation is observed. In reality, the vector field determined according to the invention has a more complicated appearance.

[0145] FIG. 17 shows a schematic diagram of an excerpt of an image superposition of ideal and real structuring and ideal and real position marks at a location. This illustration is used to mathematically explain the relationship of the various quantities that can be calculated and measured. The exact illustration of the location marks has been omitted for the sake of clarity. The coordinate axes of the coordinate systems of the ideal and real planes have already been adapted to each other, so that all coordinate systems have the same orientation and the same origin as each other. The relationships of all other difference vectors can be seen, except for the optical errors, which are not shown explicitly but are only mentioned in formulas. The positions of the ideal position mark 3i and the ideal structuring 11i exist in the computer. The positions of the real position mark 3r and the real structuring 11r are measured. The difference vector r according to the invention is calculated by the following equation: Sr,Mr can be measured. The discrepancy vector r Si,Mi can be calculated directly from the computer data; no measurements are required. The discrepancy vector r Mr,Mi can also be measured. From the acquired data, the discrepancy vector r Sr,Si That is, the deviation of the position of the actual structured portion 11r from the position of the ideal structured portion 11i is calculated. [Explanation of symbols]

[0146] 1,1' mark 2 Location Mark 3,3',3i,3r position marks 4. Mark Field 5,5',5'' Markfield carrier 5o,5o',5o'' Markfield carrier surface 5r,5r'' Markfield carrier back side 6 Object-fixed coordinate system 7 Substrate 7o Board surface 8,8',8'',8''' PCB holder 8o Substrate holder surface 8r Back side of board holder 9 Fixed elements 10 pillars 11,11i,11r structure 11c Distinctive structural features 12 Fixing means 13,13' Optical system 14 Penetration

Claims

1. Mark Field (4), at least two location marks (2) containing information about the location of each of said location marks (2) within said mark field (4); at least one position mark (3) assigned or assignable to one of said location marks (2), A mark field (4) comprising:

2. 2. The mark field according to claim 1, wherein the location marks (2) and / or position marks (3) are arranged with uniform spacing between the location marks (2) and / or position marks (3) in an arbitrary, in particular symmetrical, raster.

3. 3. The mark field according to claim 1 or 2, wherein adjacent location marks (2) and / or adjacent position marks (3) are equally spaced on the mark field (4).

4. 4. The mark field according to claim 1, wherein the mark field (4) has at least 10x10 marks (1), preferably at least 100x100 marks (1), more preferably more than 1000x1000 marks (1), particularly preferably more than 10000x10000 marks (1), most preferably more than 100000x100000 marks (1).

5. 5. The mark field according to claim 1 , wherein the spacing between adjacent location marks (2) is smaller than the width and / or height or diameter of the location marks (2), in particular the ratio of the spacing to the width and / or height or the diameter of the location marks (2) is smaller than 1, more preferably smaller than 0.5, even more preferably smaller than 0.

1.

6. 6. The mark field according to claim 1, wherein each mark (1) of the mark field (4) is different from the others, in particular each mark has a different code, preferably a position code.

7. Said location marks have the following characteristics: - QR code, - barcode, - geometrical, especially three-dimensional figures, - a string of symbols, in particular a string of letters and / or numbers, preferably a binary code, -image, 7. The mark field according to claim 1, further comprising one or more of the following:

8. 1. An apparatus for determining an X-Y-position of a structural feature (11c) of a structured portion (11) arranged on a substrate (7), said X-Y-position being determinable relative to a mark field (4) formed according to any one or more of claims 1 to 7, said mark field (4) being fixed with respect to said substrate.

9. 1. A method for determining the XY-position of a structural feature (11c) of a structured portion (11) arranged on a substrate (7), comprising: a mark field (4) fixed relative to said substrate (7), at least two location marks (2) containing information about the location of each of said location marks (2) within said mark field (4); at least one position mark (3) assigned or assignable to one of said location marks (4), having determining said XY-position relative to said mark field (4); method.

Images