Method and apparatus for aligning a substrate

Abstract

An apparatus and method for aligning a substrate are described.

Description

Background Technology

[0001] Many alignment systems exist in the prior art. Many of these systems are based on a measuring device inserted between two substrates to measure alignment marks. A disadvantage of this system is that the measuring device introduced between the substrates can contaminate the surface of the lower substrate. Another significant disadvantage is that the measuring device has a certain height. Therefore, the two substrates must be at least that height apart. After the measuring device has measured the surfaces of both substrates and been removed, the substrates must still always be close to each other and close to each other along the entire distance between them. During this close proximity, a re-displacement occurs in the lateral direction between the substrates, thus invalidating the previous lateral alignment of the substrates relative to each other.

[0002] A further development of the prior art is an alignment system in which the facing surfaces of substrates are spaced only a few millimeters, preferably even only a few micrometers, and most preferably even only a few nanometers apart. This minute gap does not allow for the insertion of a measuring device. However, in order to align the substrates with each other according to the alignment marks of the measuring device, the substrates must be laterally displaced relative to each other. Then, multiple optical devices measure the alignment marks in the laterally displaced state, and calculate the position that the substrate holder must occupy to accurately align the alignment marks. This alignment system is described in detail in published documents US6214692B1, WO2014202106A1, WO2015082020A1, and WO2011042093A1. A substrate holder that can be positioned very precisely is a prerequisite for this alignment system. Furthermore, the position of the substrate holder must be accurately measured at any given time.

[0003] The biggest problem with existing technologies is that the substrate must be positioned via a substrate holder, and positioning can only be performed with the same precision as manipulating the substrate holder or measuring its exact position. Since the lateral travel of the substrate holder is several millimeters to several centimeters, achieving, and especially reproducible, positioning in the micrometer or nanometer range is extremely difficult. Very accurate position measurement systems, particularly interferometers, are required, which can be correspondingly expensive, maintenance-intensive, and error-prone. Summary of the Invention

[0004] Therefore, the object of the present invention is to provide a method and an apparatus that at least partially eliminate, and in particular completely eliminate, the disadvantages mentioned in the prior art. In particular, the object of the present invention is to provide an improved method and an apparatus for precisely aligning two substrates with each other.

[0005] This task is solved using the features of the independent claim. Advantageous extensions of the invention are described in the dependent claims. All combinations of at least two features described in the specification, claims, and / or drawings also fall within the scope of protection of the invention. In the case of the stated value range, values ​​within the mentioned limits should also be considered as the disclosed limits and can be claimed in any combination.

[0006] Therefore, the present invention relates to an apparatus for aligning a substrate, comprising:

[0007] - A first substrate holder for receiving a first substrate, wherein the first substrate has at least two alignment marks.

[0008] - A second substrate holder for receiving a second substrate, wherein the second substrate has at least two additional alignment marks.

[0009] - At least one alignment optics for detecting these alignment marks.

[0010] in,

[0011] - The device also features:

[0012] - At least one positioning optics for detecting position marks, wherein alignment marks of the first substrate and other alignment marks of the second substrate can be aligned with each other based on these position marks.

[0013] These position marks can be used for accurate alignment when aligning these substrates or their alignment marks. Here, the position of these alignment marks relative to these position marks can be determined, and the substrate holder can be advantageously manipulated using the position marks as a reference. Thus, it is advantageous that alignment is not performed via these alignment marks, allowing for precise alignment even when these alignment marks are not readily available for these alignment optics, especially when the substrates and thereby these alignment marks are arranged very close to each other. In particular, the position for aligning these substrates, especially the alignment marks arranged on these substrates, can be determined when the substrate surfaces, arranged on each other and pointing towards each other, are only a few millimeters apart, especially only a few nanometers apart. It is also advantageous that common alignment systems can be easily and advantageously extended according to aspects of the invention. It is also advantageous that the lateral distance the substrates are moved during alignment is kept as small as possible.

[0014] The present invention also relates to a method for aligning two substrates, particularly using a means for aligning substrates, the method comprising at least the following steps, particularly the following process:

[0015] i) Fix the two substrates to each of the substrate holders.

[0016] ii) Inspect the alignment marks on these substrates,

[0017] iii) Detect location markers,

[0018] iv) Align the alignment marks on these substrates with each other according to these position marks.

[0019] During this alignment, the positions of the alignment marks are first detected after the substrates are fixed. Simultaneously or subsequently, the positions of these alignment marks are associated or correlated with the positions of these location markers. Preferably, no relative movement of the substrates occurs when the reference is specified. The substrates or the alignment marks arranged on them can then be advantageously aligned using these location markers.

[0020] In a preferred embodiment of the invention, it is specified that when one or more of at least two alignment marks on the first substrate are obscured by the second substrate for the at least one alignment optics and / or when one or more of at least two other alignment marks on the second substrate are obscured by the first substrate for the at least one alignment optics, the alignment marks on these substrates can be aligned with each other by means of these position marks. Thus, the alignment can also be advantageously performed in the obscured state by means of the position marks used as references. In particular, it is then unnecessary to move these substrates to detect the position of these alignment marks during alignment. Therefore, relative movement over large distances can be avoided. This allows for particularly precise alignment.

[0021] In another preferred embodiment of the invention, a position mark field is formed by position marks, particularly regularly arranged position marks, wherein the orientations of different position marks relative to each other, and especially their orientations relative to each other within the position mark field formed by these position marks, are known. Preferably, these position marks are regularly arranged in the position mark field. Preferably, the position marks in the position mark field are arranged side by side in a plane. It is also conceivable to form multiple position mark fields, each having multiple position marks, on the device. In particular, here, the position of each position mark or the orientation of each position mark within the field is known. Thus, it is advantageous that the position of another position mark can be detected using each position mark. It is also advantageous that the positioning optics need not be moved relative to the position mark field. More precisely, the positioning optics can also be held in the desired position and aligned by moving the substrate holder. Furthermore, the reference for the alignment mark can advantageously be set to different position marks or associated with different position marks. In particular, the position can be calculated because the orientations of the position marks detected by the positioning optics relative to other position marks are known.

[0022] The length of the position marking field is greater than 0.1 mm, preferably greater than 1 mm, even more preferably greater than 10 mm, most preferably greater than 100 mm, and most preferably greater than 300 mm.

[0023] The width of the position marking field is greater than 0.1 mm, preferably greater than 1 mm, even more preferably greater than 10 mm, most preferably greater than 100 mm, and most preferably greater than 300 mm.

[0024] It is also advantageous to specify that a relatively large position mark field is generated so as to cover the very large displacement paths of these substrate holders. Therefore, by using a large position mark field, it is advantageous to perform accurate positioning of the substrate holders at any point in time.

[0025] In another preferred embodiment of the invention, these position marks are formed by a plurality of fine positioning elements, particularly irregularly arranged. The arrangement of these fine positioning elements is known in particular. Thus, fine positioning can be advantageously performed during alignment using these fine positioning elements. Each fine positioning element can also be detected by the positioning optics. Here, it is particularly specified that the fine positioning is performed using a fine positioning element of a particular position mark. In particular, it can be specified that a position mark includes a specific fine positioning element, which can be considered as the origin of a coordinate system and detected as the origin. Thus, the distance or orientation of each individual fine positioning element relative to that specific fine positioning element of the position mark can be advantageously determined. Advantageously, the positional relationship with the alignment mark can be precisely defined. It is also advantageous that the alignment of these alignment marks or these substrates relative to each other can be performed in this way.

[0026] In another preferred embodiment of the invention, each position mark is formed differently, wherein these position marks have specific information content, particularly detectable by positioning optics. By means of these differently formed position marks, the corresponding position mark can be identified and assigned an orientation within the position mark field. Preferably, this is achieved by different arrangements of fine positioning elements. In particular, the information content can be obtained through the arrangement of these fine positioning elements and thereby the position marks themselves. In particular, this information content is known or stored in memory. Thus, after detecting the position mark, the precise position of the corresponding position mark within the mark field can be known. Preferably, when the detected position mark has been set as a reference for alignment marks, the alignment of these substrates relative to each other can be performed on this basis.

[0027] In another preferred embodiment of the invention, these location markers are specified to have one or more of the following implementations:

[0028] - QR code

[0029] - Barcode

[0030] - Geometric figures, especially three-dimensional geometric figures.

[0031] - Strings, especially sequences of letters and / or numbers, preferably binary codes.

[0032] - Image.

[0033] Different implementations can store information at varying heights within these location markers. Preferably, the use of QR codes is provided. Advantageously, precise alignment of these substrates relative to each other can be achieved under different process parameters.

[0034] In another preferred embodiment of the invention, at least one substrate holder and / or the at least one positioning optics are movable in at least two directions, particularly in the x and y directions. To establish a correlation between alignment marks and position marks, it is particularly necessary to move at least one substrate holder and / or the at least one positioning optics relative to the corresponding substrate surface and / or relative to these position marks. For this purpose, openings can be provided in the substrate holder to allow fixed and / or movable optics to detect the corresponding marks through the substrate holder. In this way, it is advantageous to keep the lateral movement of these substrates relative to each other as small as possible during alignment.

[0035] In another preferred embodiment of the invention, the position marks are arranged laterally next to at least one of the substrates, so that the alignment marks on the substrates can be aligned with each other, especially when the alignment marks of one substrate are obscured by the other substrate for the at least one alignment optics. This is particularly true when the substrates are arranged on top of each other. When the surfaces of the substrates to be joined, which are substantially aligned in the directional direction, are arranged very close to each other, the alignment marks arranged on these substrates are obscured by the corresponding other substrate. Preferably, the position marks are arranged outside the substrate on a plane extending from the respective substrate surface and are therefore not obscured. Thus, advantageously, alignment can be performed using these position marks even when the substrates are arranged very close to each other.

[0036] In another preferred embodiment of the invention, these position marks are arranged on at least one of the substrate holders. These position marks are preferably arranged on the respective substrate holders. Thus, the position of these position marks can be advantageously directly correlated with the movement of the respective substrate holder. The movement or orientation of these position marks, detected by the positioning optics, is directly coupled, in particular, to the movement of the respective substrate holder. Therefore, alignment can be advantageously and precisely performed.

[0037] In another preferred embodiment of the invention, these position marks are arranged on the surface of at least one substrate holder. These position marks are preferably arranged on the surface of the substrate holder. In this way, the field of view of these position marks for the positioning optics is not obstructed by other components arranged on the substrate holder.

[0038] In another preferred embodiment of the invention, these position marks are arranged at the same height as the substrate surface of at least one of the substrates. Alignment marks preferably arranged on the substrate surface are preferably located at the same height as these position marks. This advantageously allows the correspondingly adjusted focal points of the positioning optics and the alignment optics to be aligned identically, especially when the positioning optics and the alignment optics use the same focusing unit. Additionally, the alignment marks and the position marks set as references are located at the same axial height. Therefore, the substrate holder only needs to move further in the x and / or y directions for alignment.

[0039] In another preferred embodiment of the invention, it is specified that when aligning the alignment marks of these substrates with each other, the positions of the alignment marks of these substrates can be detected, particularly continuously, by the at least one positioning optics. Preferably, the current orientation of these substrates can be determined by the positioning optics at any point in time after these alignment marks and these position marks are associated. Advantageously, other additional method steps can also utilize the precise orientation information of these substrates. Continuously checking the orientation while moving these substrate holders and / or the positioning optics can also advantageously record deviations from the determined or desired orientation. In this way, early identification of errors can be achieved during the alignment process.

[0040] This invention describes a method and apparatus for aligning substrates. Alignment marks on two substrates, aligned with each other, are located on the surfaces of the substrates facing each other. Therefore, especially at least during bonding, the alignment marks on each substrate are obscured by the corresponding opposite substrate. The idea describes the use of at least one position mark field, particularly a QR field, which improves the positioning accuracy of the substrate holders and the substrates thereon. In this respect, the positions of the alignment marks relative to each other can be accurately calculated without having to observe the alignment marks. The idea is described in detail for three types of alignment systems.

[0041] The essence of this invention lies particularly in providing an apparatus and method by means of which two substrates are aligned based on alignment marks using an optical system. These optical devices are alignment optics known from the prior art, by means of which the alignment marks are improved. According to the invention, at least one, particularly an additional, positioning optics is used, by means of which at least one position mark field, particularly a QR mark field, can be optically measured. This position mark field serves as a reference field so that the substrate holders and thereby the accurate positions of the substrates can be determined.

[0042] While the method and corresponding apparatus are still always required to perform lateral displacement of these substrate holders, the current actual position of the substrate holders is detected by several position markers in the position marker field, especially QR markers, at least at the point in time when these alignment markers are no longer visible or detectable by the alignment optics. These position markers are readable and interpretable by software and / or hardware and / or firmware. "Interpretable" means that coarse position information is encoded in the markers themselves. Fine positioning can then be performed using pixel positions.

[0043] With the aid of this device and the corresponding method, it is possible to continuously or accurately calculate the precise position of the alignment marks, especially when these alignment marks are obscured by the corresponding opposite substrate, rather than by measuring the alignment marks themselves.

[0044] This idea is particularly a preferred alternative to more expensive, error-prone, and maintenance-intensive position measurement systems, especially extensions of interferometers.

[0045] Another major advantage is that the idea can be easily applied to existing systems and can be extended to these existing systems.

[0046] Therefore, it is not necessarily necessary to redevelop the alignment system.

[0047] This idea is based, for example, on alignment systems from published documents US6214692B1, WO2014202106A1, WO2015082020A1, and WO2011042093A1. Therefore, only a brief discussion of the descriptions of these alignment systems will be given, but the idea will be described in detail according to the three methods that can be assigned to these alignment systems in order to demonstrate the flexibility of the idea.

[0048] Importantly, all alignment systems, especially those mentioned in the published literature above, can be extended according to aspects of the invention. That is, the main idea is to use a position mark field, particularly a QR mark field, and at least one additional position mark optics, to measure the position marks of the position mark field at a predetermined time point, while simultaneously using alignment optics to measure the position of at least one alignment mark. Since the at least one position mark optics no longer moves relative to the alignment optics, even if the alignment mark is obscured, the position of the alignment mark can always be calculated and thus known by measuring the position marks of the position mark field.

[0049] mark

[0050] To describe the idea as well as possible, a distinction is made between alignment marks and position marks.

[0051] Alignment Marks

[0052] Alignment marks are understood to be those marks that have been coated or generated on these substrates and must be coincident in the process, especially those that must be precisely aligned with each other. Alignment marks are used for the accurate positioning of two substrates relative to each other. The smaller the distance between the alignment marks on the two substrates, the more effective the alignment achieved by the alignment marks. Therefore, a so-called back-to-back alignment, where the alignment marks are located on the back sides of the substrates, is less efficient than a so-called face-to-face alignment, where the alignment marks are located on the surfaces of the substrates to be joined, especially facing each other. However, a disadvantage of this face-to-face alignment is that the alignment marks on the surface of the first substrate are obscured by the correspondingly opposite second substrate because these alignment marks are close together. If a measurement method in which the substrates cannot be measured by transmission is chosen, it is impossible to detect the alignment marks in this state and therefore impossible to correctly align the substrates with each other. Although infrared measurement at some substrates would theoretically be an option for aligning the substrates with each other, this method is often unusable due to the metallic coating of the substrates. Metal is essentially opaque to infrared light. That is, the remaining option is simply to measure the alignment marks while the corresponding opposite substrates are displaced, so that after measuring these alignment marks, the substrate holders and thereby the substrates are aligned with each other by means of a high-precision positioning process.

[0053] The precise form of alignment marks does not need to be discussed in more detail, because countless types of alignment marks exist in industry. In the accompanying drawings of this publication, alignment marks are simplified using black crosses.

[0054] Location marker

[0055] Position marks are understood to be marks that are continuously tracked, observed and evaluated by additional optics, positioning optics and especially by additional optics, so that even when the alignment marks on the substrate are obscured by the corresponding opposite substrate and thus no longer optically accessible, the substrate holders and the accurate position of the substrates can be determined.

[0056] These location markings are preferably located on the substrate holder.

[0057] Preferably, each location marker is manufactured such that a location, especially a rough location, can be read from the location marker. Particularly suitable as location markers are:

[0058] • QR code,

[0059] • Barcode,

[0060] • text

[0061] • Symbol

[0062] • etc.

[0063] In QR location markings, especially approximate locations, the location is directly encrypted within the QR code. The location markings shown in the accompanying figures of this publication are QR codes. To better understand this publication, commercially available QR scanners, such as smartphone cameras, can be used to read the QR codes. Thus, those skilled in the art who read this publication can easily understand the approximate location.

[0064] Barcode location markers might store the approximate location as an integer in an encrypted manner. For example, one could envision the integer 101012 representing the approximate location (101, 012). The consensus is that the first n digits of the N numbers correspond to the x-coordinate, and the last Nn digits correspond to the y-coordinate.

[0065] If text is used as a location marker, the approximate location can be directly represented as text. For example, one could imagine using the text fragment "101, 12" to specify the approximate location (101, 12).

[0066] In the case of symbolic position marking, an assignment table is particularly necessary. Special symbols are assigned to coarse positions (x, y). Alternatively, it can be envisioned that a symbolic position marking consists of two partial symbols, each corresponding to coordinates already specified in an assignment table.

[0067] Furthermore, each location marker preferably possesses fine positioning elements through which its fine position can be assigned to the location marker. The positions encrypted within the location marker are typically insufficient for performing fine positioning.

[0068] Fine positioning elements can be, for example, frames surrounding a position mark. Rectangles, especially squares, are conceivable, for example. Symmetrical octagons or circles are also conceivable. These fine positioning elements can be detected and evaluated by hardware and / or software and / or firmware such that a local zero point of the position mark is obtained through these fine positioning elements, which is limited only by the pixel resolution of the detector. Fine adjustment can then be achieved through the relative displacement of this zero point relative to the optical axis of the positioning optics, thus enabling, in particular, accurate alignment of the substrate, or calculations to determine the accurate position of the alignment mark and thereby, in particular, the accurate position of the substrate fixed to a substrate holder. It is also conceivable that individual features of the position mark, such as corners or sides, themselves serve as fine positioning elements.

[0069] Location marker field

[0070] The location markers, especially the location marker field, are arranged symmetrically, particularly along the grid, within the location marker field. The positions encoded in the location markers are defined relative to the origin of the location marker field.

[0071] Ideally, the position marking field should be generated on the surface of an object whose shape changes only very slightly, preferably not at all, regardless of variations in physical parameters such as pressure and temperature. Therefore, the object on which the position marking field is generated should have a thermal expansion coefficient tensor with the smallest possible coefficient. This object is preferably made of a material with a cubic crystal system, because thermal expansion is always isotropic in this case. In this case, the thermal expansion coefficient can be simply used instead of the expansion coefficient tensor.

[0072] The material should be as insensitive as possible to the adsorbate, especially avoiding oxidation or other chemical reactions that lead to layer formation. In particular, nano-thin oxide layers can possess very pronounced optical properties that may adversely affect the reading of position markers. Examples include interference effects and light refraction.

[0073] In a very particularly preferred embodiment, the position mark field is located at approximately the same height as the alignment mark to be measured, and in particular within a plane extended by the surface of the substrate on which the alignment mark is arranged.

[0074] In a less preferred embodiment, the position mark field is located on the outer surface of the substrate holder opposite to the substrate holder fixing surface, and thereby is relatively far from the plane where the alignment mark is located.

[0075] Regarding the position marker field, preferably there exists a separate coordinate system (position marker field coordinate system PMFKS) with a corresponding xP axis and a yP axis that is preferably orthogonal to it. One of these position markers is preferably the zero position marker that defines the PMFKS.

[0076] The establishment of a position mark field is always accompanied by inaccuracies. Each product produced can only be manufactured with the precision and accuracy of the production machine. Therefore, it is important to note that it is not necessary to generate a position mark field isotropically and / or uniformly over the entire area. It is perfectly sufficient that the position marks already associated with the alignment marks do not change during the alignment process.

[0077] Preferably, the goal is still to obtain a position marking field that is generated as accurately and precisely as possible over the entire position marking field area.

[0078] Optical devices

[0079] In the following text, a distinction is generally made between alignment optics and positioning optics. Alignment optics are understood as all optics that detect alignment marks, while positioning optics are understood as all optics that measure position marks. In particular embodiments, optics are used that function as both alignment and positioning optics. In these cases, the two terms can be used synonymously. However, since this aspect of the idea is based on the fact that further developments in alignment systems with alignment optics are always already available, the term "positioning optics" is used in this context to maintain continuity and consistency.

[0080] In the following text, the term "optical device" is used as a synonym for a generally very complex optical system, that is, several optical elements, based on which images are captured, and especially magnified. Optical devices are symbolically represented in an image by simple objective lenses. However, behind these optical devices may be other optical elements, such as prisms, various lenses, filters, plane mirrors, etc. These optical devices project the captured image onto a chip, especially a CMOS chip, which further processes the image accordingly, and especially transmits the image to software.

[0081] Typically, all optics are capable of translation and / or rotational movement. However, after the corresponding calibration of the optics, it is preferable that these optics are no longer moved. Subsequently, relative movement between the optics and the substrate holder is achieved only through movement of the substrate holder. In particular, the focal plane or focus and / or depth-of-field range of the optics is adjustable and preferably not changed after calibration onto the plane. The main exception is the optics of the Type 3 alignment system, which is mentioned in detail later in publication WO2015082020A1. In this alignment system, it is precisely the active movement of the optics that is required to achieve the desired alignment result.

[0082] position

[0083] This method allows for the accurate positioning of a substrate holder and thereby the substrate through the measurement and precise manipulation of the position of the position marker field. To accurately manipulate the substrate holder, reading a coarse position from the position markers in the positioning field is insufficient because this coarse position only indicates a position far above the possible optical resolution limit. Once the position markers in the position marker field are within the field of view of the positioning optics, the zero point of the position markers can be measured. Fine positioning of the substrate holder is then performed by measuring the distance between the zero point of the positioning optics and the zero point of the position markers. This fine positioning is limited by the pixel resolution of the detector, as pixel resolution is inferior to optical resolution, which in other cases is the resolution limit. That is, during the movement of the substrate holder, the positioning optics must cooperate with hardware and / or software and / or firmware to read only the coarse position of the substrate holder by reading the position markers that pass through the field of view of the positioning optics. Then, once the desired coarse position is reached, fine positioning can be performed by pixel measurement. During this measurement phase, the substrate holder, especially when completely still or moving slowly, allows for the measurement of all required position marker features.

[0084] substrate holder

[0085] The substrate holder particularly has a substrate holder fixing surface and a substrate holder outer surface opposite to the substrate holder fixing surface.

[0086] The substrate holder has fasteners. These fasteners are used to secure the substrate. These fasteners can be:

[0087] 1. Mechanical fasteners, especially

[0088] 1.1. Clamping Pliers

[0089] 2. Vacuum fasteners, which particularly have

[0090] 2.1. Individually operable vacuum track

[0091] 2.2. Interconnected vacuum orbits

[0092] 3. Electrical fasteners, especially

[0093] 3.1. Static electricity fasteners

[0094] 4. Magnetic fasteners

[0095] 5. Adhesive fasteners, especially

[0096] 6. Gel-Pak fasteners

[0097] 7. Fixtures with adhesive, especially manipulable, surfaces.

[0098] The fasteners are particularly electronically operable. Vacuum fasteners are a preferred type. Vacuum fastening preferably comprises multiple vacuum tracks extending from the surface of the substrate holder. These vacuum tracks are preferably individually operable. In one application, some vacuum tracks are combined into vacuum track segments, which are individually operable, meaning they can be evacuated or filled. Each vacuum segment is particularly independent of the others. This allows for the construction of individually operable vacuum segments. These vacuum segments are preferably designed in a ring shape. This enables targeted, radially symmetrical, and particularly inside-out fastening and / or separation of the substrate and substrate holder.

[0099] The substrate holder can be a substrate holder derived from one of the published documents WO2017162272A1, WO2018028801A1, and WO2019057286A1, which has been extended to reflect the properties of the invention. This substrate holder is particularly a substrate holder having a separately operable region and fixing elements according to the embodiment of WO2017162272A1.

[0100] The location marking field can be located on the substrate holder fixing surface and / or the substrate holder outer surface.

[0101] In a particularly preferred embodiment, the position marking field is located on the fixing surface of the substrate holder. The advantage of this embodiment is that the depth of field of the positioning optics is at the same height as the depth of field of the alignment optics, which are located, in particular, on the same side as the positioning optics.

[0102] In yet another preferred embodiment, the position marking field is located at the same height as the surface of the substrate to be bonded. Since the substrate has a certain thickness, either the position marking field must be raised relative to the substrate holder fixing surface, or the substrate holder fixing surface must be slightly moved back within the substrate holder. This can be achieved, for example, by milling with a milling depth that approximately corresponds to the average substrate thickness.

[0103] In a typical implementation, the substrate holder within the device has six degrees of freedom, thus allowing displacement in the x, y, and z directions, as well as rotation about the x, y, and z axes. In a particular implementation, the substrate holder within the device preferably moves only a minimum number of degrees of freedom to minimize the error caused by devices that allow other degrees of freedom.

[0104] For some of the alignment systems mentioned, the optics must be moved very close to alignment marks on the substrate. Therefore, the substrate holder may have holes, channels, drilled holes, milled holes, recesses, or indentations, referred to hereinafter by the superordinate concept of an opening, to allow the optics unobstructed access, particularly for lateral displacement. Transparent material can also be inserted into the opening. This is particularly applicable to the alignment system according to publication WO2015082020A1.

[0105] Device

[0106] The device is an alignment system. Different types of alignment systems are classified into four types.

[0107] Type 1 is an alignment system based on the alignment principle of published document US6214692B1. In principle, it involves displacing at least one of the substrate holders along a direction, particularly perpendicular to the connecting line of the two alignment marks, and within the substrate surface. In this manner, the substrate holders are displaced along a relatively long path. The mutual displacement of the substrate holders associated with four alignment optics allows for alignment of the two substrates while the distance between them is very small, with each of the four alignment optics, two opposing optics respectively, being calibrated to a focal point within the focal plane.

[0108] Type 2 is an alignment system based on the alignment principle of published document WO2014202106A1. In principle, it involves the cross-displacement of two substrate holders along a direction parallel to the connecting line of the two alignment marks and within the substrate surface. That is, unlike Type 1, these substrates are "laterally" displaced. Due to this lateral displacement, the displacement of the substrate holders is much shorter than in the Type 1 alignment system. The mutual displacement of the substrate holders associated with four alignment optics allows for alignment of the two substrates while the distance between them is very small, with two opposing optics of these four optics calibrated to a focal point within the focal plane. Therefore, it is preferable to use a substrate holder in which the locally confined position mark field is located next to the alignment marks of the substrate to be loaded.

[0109] Type 3 is an alignment system based on the alignment principle described in published document WO2015082020A1. In principle, it involves fixing or allowing at most z-direction movement of an optic on one side, particularly the lower side, while allowing free movement of an optic on the opposite side, particularly the upper side, in multiple directions, particularly at least in the x and y directions. Furthermore, in this type of alignment system, one of the substrate holders, particularly the lower substrate holder, can also move only in one direction, particularly the z-direction. Compared to Type 1 and Type 2 alignment systems, the optics here are very easily moved after the calibration process, while the lower substrate is initially fixed and moved only in the z-direction by the lower substrate holder during the bonding process.

[0110] Type 4 is based on all other types of alignment systems based on optical principles. Here, in principle, all types of position marker fields can be used in any combination. The disadvantages of position marker fields placed on the outer surface of the substrate holder have been described in detail in the section on position marker fields. Therefore, the general Type 4 alignment system will only be briefly discussed below in this publication. For example, a Type 4 alignment system would be the alignment system described in publication WO2011042093A1. This publication describes an alignment system in which the substrate holder can move a long distance on the substrate, wherein alignment optics are secured to the substrate and / or fixed to the substrate holder, etc.

[0111] A type 3 alignment system with a corresponding extension according to the present invention is preferred.

[0112] In a very particularly preferred embodiment, the device has at least four alignment optics and at least one positioning optics, but preferably two positioning optics. Due to symmetry, two positioning optics are always used in this publication, especially in the accompanying drawings, although one would be sufficient.

[0113] In one embodiment, at least one of the substrate holders is designed as a substrate holder, that is, a substrate holder with a position marking field.

[0114] In a particularly preferred embodiment, both substrate holders are equipped with position marking fields. Correspondingly, corresponding positioning optics can be used to determine the precise position of each substrate holder. A corresponding number of positioning optics are required, i.e., at least two, one above and one below.

[0115] Typically, this apparatus and method are not associated with any particular type of alignment system mentioned. The basic idea is to measure and establish the correlation between alignment marks and position marks in a position mark field. Nevertheless, apparatus and processes for different implementation types are clearly described and presented in the accompanying drawings. In particular, this idea should be used to extend the Type 3 alignment system of WO2015082020A1.

[0116] method

[0117] It is irrelevant whether the extended one or more substrate holders are located on the upper or lower side of the device. For consistency with the figures in this publication, the following description assumes that the substrate holders are upper substrate holders, that is, the position marking field points downward in the direction of gravity.

[0118] The calibration procedure is usually performed before this method. A calibration procedure should be performed whenever it is assumed that the optical system has been changed or adjusted. The calibration procedure depends on the type of alignment system used. Possible calibration procedures are disclosed in detail, for example, in publications WO2014202106A1 and WO2015082020A1, and will not be discussed further.

[0119] The alignment process can begin after the calibration process provided for the corresponding alignment system is completed.

[0120] This method is applicable in principle to alignment systems in which the substrate is moved, in particular, along (i) a direction perpendicular to the line connecting the two alignment marks and (ii) parallel to the substrate surface. This alignment system is described in US6214692B1 and referred to as Type 1. Here, the substrate must travel a relatively long distance to make the alignment marks visible to the optics. These alignment marks are measured quasi-parallel here.

[0121] In a first process step of an exemplary method according to the invention for aligning two substrates using a type 1 alignment system, the first substrate is loaded and secured to a first, upper substrate holder.

[0122] In the second process step, the first and upper substrate holders are continuously moved until the alignment marks of the first and upper substrates are within the field of view of the lower alignment optics. The lower alignment optics simultaneously measure the upper position marks at the first and upper substrate holders, ensuring they are within the field of view of these lower alignment optics. From this point onward, the first and upper substrate holders can be moved along their entire length and repositioned to the same location by remanipulating the upper position marks.

[0123] In the third process step, the first upper substrate holder is now moved to a position where the then-obscured upper alignment optics have a downward free field of view. Specifically, simultaneously with or in parallel with the previous process steps, the second substrate is loaded and secured to the second lower substrate holder. Of course, the loading of the second substrate can also have been performed at a much earlier time, particularly in parallel with one of the process steps mentioned above.

[0124] In the fourth process step, the second and lower substrate holders are continuously moved until the alignment marks of the second and lower substrates are within the field of view of the upper alignment optics. Then, preferably, the second and lower substrate holders are no longer moved.

[0125] In the fifth process step, the first and upper substrate holders are moved back to the positions determined in the second process step. Here, only lower positioning optics are used, which continuously measure the upper position mark field at the first and upper substrate holders, thus allowing for the most precise manipulation of the desired position. In particular, fine-tuning is also performed using positioning optics, which is discussed in more detail in other parts of this publication.

[0126] In the following process steps, the two substrates are then joined together through corresponding processes. The joining process will not be discussed further here. A welding process is conceivable, in which one of the two substrates, especially the upper substrate, is bent by a bending device to make contact with the other substrate.

[0127] Here, a possible first improvement to the process mentioned above is presented in a simplified form. The upper substrate holder has openings through which an upper alignment optics can observe the lower substrate holder and, consequently, the loaded lower substrate. The lower substrate holder has a position mark field on its back side. The substrate is loaded onto the lower substrate holder, and the alignment marks of the lower substrate are measured through the openings of the upper substrate holder using the upper alignment optics. Simultaneously, a lower positioning optics measures the position mark field on the back side of the lower substrate holder. Then, the upper substrate is loaded. In particular, the lower substrate holder is simultaneously moved so that the lower alignment optics can measure the degree of alignment of the upper substrate at the upper substrate holder. Then, the lower substrate holder can be brought back to the correct position using the positioning optics.

[0128] Here, a possible second improvement to the process mentioned above is presented in a simplified form. The lower substrate holder has openings through which a lower alignment optics can observe the upper substrate holder and, consequently, the loaded upper substrate. The upper substrate holder has a position mark field on its back side. The substrate is loaded onto the upper substrate holder, and the alignment marks of the upper substrate are measured through the openings of the lower substrate holder using the lower alignment optics. Simultaneously, an upper positioning optics measures the position mark field on the back side of the upper substrate holder. The lower substrate is then loaded. In particular, the upper substrate holder is simultaneously moved so that the upper alignment optics can measure the degree of alignment of the lower substrate at the lower substrate holder. Then, the upper substrate holder can be brought back to the correct position using the positioning optics.

[0129] Combining the two mentioned improvements is also conceivable.

[0130] An improved embodiment of the alignment system and its improved method is described in WO2014202106A1 and referred to as Type 2. Here, the substrates are also displaced relative to each other, but along the direction of the connecting line of the two alignment marks, i.e., "laterally," so that the first alignment mark of the first substrate can always be detected by the second alignment optics and the second alignment mark of the second substrate can always be detected by the first alignment optics. The alignment marks are measured here quasi-"transversely." Correspondingly, slight variations occur in the process flow. In particular, at least one substrate holder in the Type 2 alignment system is also extended to include a position mark field.

[0131] In the first process step of an exemplary method according to the invention for aligning two substrates using a type 2 alignment system, a first substrate is loaded and secured to a first, upper substrate holder. Specifically, a second substrate is simultaneously loaded and secured to a second, lower substrate holder. After loading and securing the substrates, the substrate holders are positioned such that the lower left alignment optics have the upper left alignment mark of the upper substrate within their field of view. For this purpose, the lower substrate holder needs to be shifted to the right to the extent that the lower left alignment optics can freely observe the upper left alignment mark. Simultaneously, the lower left positioning optics must have the upper left position mark within its field of view. This establishes a correlation between the upper left position mark and the upper left alignment mark.

[0132] In the second process step, the lower substrate holder now moves to the left, thereby allowing the lower right alignment and positioning optics to measure the upper right alignment and position mark. This establishes a correlation between the upper right position mark and the upper right alignment mark.

[0133] In the third process step, the second and lower substrate holders are continuously moved until the left alignment mark of the second and lower substrates is within the field of view of the upper left alignment optics. For this purpose, an opening can be provided in the upper substrate holder. Then, preferably, the second and lower substrate holders are no longer moved. Here, once the upper substrate holder is opened to the line of view of the lower right alignment mark, the right alignment mark of the lower substrate, which is currently still blocked by the first and upper substrate holders, should be within the field of view of the upper right alignment optics.

[0134] In the fourth process step, the first and upper substrate holders are now moved to the opposite left until the upper right alignment optics can observe the lower right alignment mark of the lower substrate through the first and upper substrate holders. For this purpose, an opening can be provided in the upper substrate holder as well. In fact, the alignment mark should already be within the field of view of the upper right alignment optics. If not, the optics have been pre-calibrated to a particularly incorrect distance. Now, the upper right alignment optics measures the lower right alignment mark. The lower substrate holder should no longer be moved.

[0135] In the fifth process step, the first and upper substrate holders are moved back to their positions where the lower left and lower right positioning optics have left and right position mark fields in their field of view. Now, only the lower positioning optics are used here, which can measure the upper position mark field at the first and upper substrate holders, thus allowing for the most precise manipulation of the desired position. It is also important to understand that the lower positioning optics do not need to have both position mark fields of the first and upper substrate holders continuously in their field of view. Once the position marks of the position mark fields reappear in the field of view of the lower positioning optics, the desired position can be manipulated precisely and quickly by first coarse positioning. In particular, fine-tuning is also performed using the positioning optics, which is discussed in more detail in other parts of this publication.

[0136] In the next process step, the two substrates are then joined together through a corresponding process. The joining process will not be discussed further here. A welding process is conceivable, in which one of the two substrates, especially the upper substrate, is bent by a bending device to make contact with the other substrate.

[0137] The following paragraph describes a particularly preferred process for the Type 3 alignment system. This type of alignment system is described in publication WO2015082020A1. Applying aspects of the invention to this type of alignment system is of particular significance because it represents the latest prior art. Like the Type 2 system described previously, the alignment system is characterized primarily by a very short displacement of the substrate holder. However, here the lower components, i.e., the lower alignment optics and the lower substrate holder, are designed such that these lower components can be adjusted, in particular, only along the z-direction, i.e., along the height, while the upper alignment optics and the upper substrate holder have the maximum number of degrees of freedom, particularly in the x and y directions. The resulting advantages are described in detail in publication WO2015082020A1.

[0138] A key feature of the extended Type 3 alignment system is that the position mark field is positioned along a line that is not parallel to the connecting line of the alignment marks to be measured later, and in particular perpendicular to the connecting line of the alignment marks to be measured later.

[0139] In the first process step of an exemplary method according to the invention for aligning two substrates using a type 3 alignment system, the upper substrate holder moves to the left. Simultaneously, the left alignment optics moves upward in the z-direction until it has a left alignment mark on the upper substrate within its field of view and depth of field. Simultaneously, at least one positioning optics also moves upward until at least one position mark from one of the position mark fields is visible. This allows at least one position mark from at least one position mark field in the position mark field to be associated with or correlated with the left alignment mark.

[0140] In the second process step, the upper substrate holder moves to the right. Simultaneously, the right alignment optics 6ur move upwards in the z-direction until the right alignment optics have the right alignment mark of the upper substrate within its field of view and depth of field. Simultaneously, at least one positioning optics also moves upwards until at least one position mark of one of the position mark fields is visible. It is conceivable that both positioning optics have already been positioned through the first process step. It is also conceivable that only one of the positioning optics was connected to the left alignment optics in the first process step, and therefore the corresponding second positioning optics must now be positioned. If this embodiment uses only one positioning optics, that positioning optics has already been positioned through the first process step and now measures the second position mark of the same position mark field. This allows at least one other position mark to be associated with the right alignment mark.

[0141] In the third process step, the lower substrate holder moves upward. In particular, the upper left alignment optics move simultaneously in multiple directions to bring the lower alignment mark of the lower substrate into the field of view and depth of field.

[0142] In the fourth process step, the substrate holder moves to the left. In particular, the upper right alignment optics move simultaneously in multiple directions to bring the lower alignment mark of the lower substrate into the field of view.

[0143] In the fifth process step, the upper substrate holder is now aligned with the lower substrate holder, such that the upper alignment mark and the lower alignment mark coincide as much as possible. Here, the movement of the upper substrate holder is checked by at least one of the positioning optics, particularly by continuously reading and evaluating at least one position mark field in the position mark field. In particular, fine positioning is performed by pixels. Therefore, even though the alignment marks are obscured by the respective opposing substrates and are no longer visible, the upper and lower substrates can be aligned.

[0144] The alignment system extended according to aspects of the invention can be based on all types of alignment systems. However, the corresponding methods and process steps differ slightly, so that the method is explicitly described in the accompanying drawings for each of the two mentioned alignment types. Attached Figure Description

[0145] Other advantages, features, and details of the invention will become apparent from the following description of preferred embodiments and from the accompanying drawings. Wherein:

[0146] Figure 1 A first substrate holder according to the present invention is shown.

[0147] Figure 2 A second substrate holder according to the present invention is shown.

[0148] Figure 3 A third substrate holder according to the present invention is shown.

[0149] Figure 4 A fourth substrate holder according to the present invention is shown.

[0150] Figure 5a The first process step in the first alignment system according to the invention is shown.

[0151] Figure 5b The second process step in the first alignment system is shown.

[0152] Figure 5c The third process step in the first alignment system is shown.

[0153] Figure 5dThe fourth process step in the first alignment system is shown.

[0154] Figure 5e The fifth process step in the first alignment system is shown.

[0155] Figure 6a The first process step in the second alignment system according to the invention is shown.

[0156] Figure 6b The second process step in the second alignment system is shown.

[0157] Figure 6c The third process step in the second alignment system is shown.

[0158] Figure 6d The fourth process step in the second alignment system is shown.

[0159] Figure 6e The fifth process step in the second alignment system is shown.

[0160] Figure 7a The first process step in the third alignment system according to the invention is shown.

[0161] Figure 7b The second process step in the third alignment system is shown.

[0162] Figure 7c The third process step in the third alignment system is shown.

[0163] Figure 7d The fourth process step in the third alignment system is shown.

[0164] Figure 7e The fifth process step in the third alignment system is shown.

[0165] Figure 8a The first process step of the fine alignment process is shown, and

[0166] Figure 8b The second process step of the fine alignment process is shown.

[0167] In these figures, the same components or components with the same function are represented by the same reference numerals.

[0168] All accompanying drawings are schematic representations of components and their features in a general, rough manner. These drawings are not to scale, and the features of the components are not necessarily designed as they are shown. Therefore, these drawings should be understood as schematic diagrams only, and their features should be interpreted functionally in all cases. Detailed Implementation

[0169] Figure 1 A first substrate holder 10 with position mark fields 3ol, 3or is shown, comprising multiple position marks 4ol, 4or, on which a substrate 2o with alignment marks 5ol, 5or is fixed. Position marks 4or are shown enlarged only on the right side. Correspondingly, position marks 4ol are present on the left side; these position marks are not enlarged for clarity. Position mark fields 3ol, 3or are located on the fixing side of the substrate holder, that is, on the same side as the fixed substrate 2o. Correspondingly, position mark fields 3ol, 3or may be located only outside the fixing area of ​​the substrate 2o. Position mark fields 3ol, 3or are present along the entire length of the substrate holder 1, particularly along one direction, in this case along the x-direction. However, it should be reiterated that such long position mark fields 3ol, 3or are not necessary for adaptation to a type 1 alignment system, and such long position mark fields may have the same position mark fields 3ol, 3or as those in an extension of a type 2 alignment system (see...). Figure 2 (Same size. However, due to the series) Figures 5a-5e The substrate holder 10 of the Type 1 alignment system described herein covers a greater distance, so the position marking fields 3ol, 3or are presented as an additional extension implemented along the entire x-direction. This substrate holder 10 is used in the Type 1 alignment system. The substrate holder 10 has a fixing element 8 and a deforming element 10. These fixing elements and the deforming element are only briefly mentioned and described because they are not essential to the concept.

[0170] Figure 2 A second, more preferred substrate holder lo' is shown, having position mark fields 3ol', 3or' including multiple position marks 4ol, 4or, and a substrate 2o with alignment marks 5ol, 5or is fixed to the second, more preferred substrate holder. Position marks 4or are shown enlarged only on the right side. Correspondingly, position marks 4ol are present on the left side, but enlarged views of these position marks are not shown for clarity. Position mark fields 3ol', 3or' are located on the fixing side of the substrate holder, that is, on the same side as the fixed substrate 2o. Correspondingly, position mark fields 3ol', 3or' may be located only outside the fixing area of ​​the substrate 2o. The substrate holder lo' preferably also has openings 9, particularly through-holes, elongated holes, apertures, or drilled holes, through which alignment optics 5ol, 5or can observe the substrate holder lo'. Openings 9 particularly simplify the view in... Figures 5a-5eThe process is shown in the diagram. In particular, the required mutual displacement of the substrate holders 10' and 11 is thus shortened. This process can also be implemented without opening 9, but it is less efficient because the required mutual displacement of the substrate holders 10' and 11 is longer in this case. Therefore, opening 9 is always drawn for completeness. The substrate holder 10' is mainly used in type 2 and type 3 alignment systems. The position marker fields 30' and 30' are smaller than Figure 1 The position markings are 3ol and 3or. The substrate holder 1o' also has a fixing element 8 and a deforming element 10. These fixing elements and the deforming element are only mentioned and described briefly because they are not essential to the idea.

[0171] Figure 3 A third, and more preferred, substrate holder 1o'' is shown, having a front position mark field 3ov and a rear position mark field 3oh comprising multiple position marks 4o. It can be seen that the connecting line between position mark fields 3ov and 3oh is not parallel to the connecting line between two alignment marks 5ol and 5or, and the position mark fields 3ov and 3oh are rotated 90° relative to the alignment marks 5ol and 5or. A characterizing feature of substrate 1o'' is that the alignment marks 5ol and 5or of the upper substrate 2o are not aligned with the position marks 3ov and 3oh; therefore, these position marks are indicated by indices v (front) and h (rear). This nomenclature is helpful in the following description of the figures. The substrate holder 1o'' also has a fixing element 8 and a deforming element 10. These fixing elements and the deforming element are only briefly mentioned and described because they are not essential to the idea. The second substrate holder 1o'' also has openings 9 that allow the alignment optics to be very close to the periphery of the substrate 2o. This will be important for the method in the later explanation.

[0172] Figure 4A fourth, sub-preferred substrate holder lo''' is shown, having a unique position mark field 3o'' comprising multiple position marks 4o, on which a substrate 2o with alignment marks 5ol, 5or is secured. The position mark field 3o'' is located outside the substrate holder. Correspondingly, the position mark field 3o'' can be created over a very large area. This substrate holder lo''' can be used in all types of alignment systems. The main disadvantage of this embodiment is that the depth of field of the alignment optics (not shown) and the positioning optics (not shown) used cannot be at the same height. The depth of field is at least separated from each other by the height h of the substrate holder lo'''. Thus, the focal planes of the alignment marks 5ol, 5or and the position marks 4o are also correspondingly far apart from each other. The position mark field 3o'' does not necessarily extend across the entire outer surface of the substrate of the substrate holder lo'''', but can be localized and smaller. Extension over a very large area is merely a further embodiment. The substrate holder lo''' also has a fixing element 8 and a deforming element 10. These fixing elements and the deforming element are only mentioned and described briefly because they are not essential to the idea.

[0173] The following figures illustrate the process, particularly the process for the Type 1 device.

[0174] To make it clearer, Figures 5a-5e It was not cut open.

[0175] Figure 5a The first process step of the first process is shown in the side view (left) and top view (right). The upper substrate holder 1o, having position marker field 3ol on the left and position marker field 3or on the right, is moved to the loading position to receive and secure the substrate 2o. It is also conceivable that the substrate 2o is secured to the substrate holder 1o rather than the substrate holder being moved. Correspondingly, the robot must move the substrate 2o to the corresponding position, where it can be secured by the upper substrate holder 1o. The device specifically includes two upper alignment optics 6ol, 6or, two lower alignment optics 6ul, 6ur, and two lower positioning optics 7ul, 7or. In the top view, fixing elements 8u are visible at the lower substrate holder 1u, which are used to secure the lower substrate 2u (not shown) in subsequent process steps. The alignment optics 6ol, 6or have been calibrated relative to the lower alignment optics 6ul, 6ur according to methods from the prior art.

[0176] Figure 5bThe second step of the first process is shown. The substrate holder 10 moves continuously in the x-direction until alignment marks 5ol, 5or are detected by alignment optics 6ul, 6ur and at least one position mark 4ol, 4or of each position mark field 3ol, 3or is detected by positioning optics 7ul, 7ur. Position marks 4ol, 4or are now represented abstractly as rectangles in these figures for simplification. Since alignment optics 6ul, 6ur and positioning optics 7ul, 7ur are no longer moving, the position of alignment marks 5ol, 5or relative to the optical axis of alignment optics 6ol, 6or, 6ul, 6ur can be determined at any time by measuring the position marks 4ol, 4or of position mark fields 3ol, 3or. It must be mentioned again here that the depth of field of the optical axis of alignment optics 6ol, 6or, 6ul, 6ur has indeed been preferably calibrated to the focal plane in the previous calibration steps. The intersection of the depth-of-field ranges of the two left-aligned optics 6ol and 6ul represents the zero point on the left side of the device, and the intersection of the depth-of-field ranges of the two right-aligned optics 6or and 6ur represents the zero point on the right side of the device.

[0177] Figure 5c The third step of the first process is shown. The upper substrate holder 10 is moved to a point where it no longer obstructs the path of the optics 6ol and 6or. Simultaneously, the lower substrate holder 10 is moved to the loading position and the lower substrate 2u is loaded. The lower substrate holder 10 secures the lower substrate 2u. In this case, it is also conceivable that the lower substrate holder 10 is not moved, and the lower substrate 2u is lowered, especially positioned, by a robot. It is also conceivable that the lower substrate 2u has been pre-loaded onto the lower substrate holder 10.

[0178] Figure 5d The fourth step of the first process is shown, in which the lower substrate holder lu is moved until the lower alignment marks 5ul, 5ur are within the field of view of the upper alignment optics 6ol, 6or. Since the upper substrate holder lo has been moved out of the field of view of the upper alignment optics 6ol, 6or in a previous process step, the substrate surface of the substrate 2u can be measured. After the lower substrate holder lu is positioned, it is no longer moved.

[0179] Figure 5eThe fifth step of the first process is shown, in which the upper substrate holder 1o moves back to its initial position. Position marks 3ol, 3or and 4ol, 4or are measured to obtain precise information about the positions of the then-obscured upper alignment marks 5ol, 5or. The positions of the lower alignment marks 5ul, 5ur must also be known, since the lower substrate holder 1u is no longer moving. Therefore, by observing the position marks 4ol, 4or of the position marks 3ol, 3or, the left alignment marks 5ol, 5ul and the right alignment marks 5or, 5ur can be aligned by shifting the position of the upper substrate holder 1o. Thus, the upper substrate holder 1o can preferably move with more than one degree of freedom. In the following process steps, the substrates 2o, 2u are then brought closer together, and the bonding process of these substrates is performed. These process steps are not explicitly shown because they do not, in particular, relate to this concept.

[0180] The following figures illustrate the process, particularly for the type 2 device. The characteristic feature of the type 2 alignment system is that the substrate holders 10 and 1u move laterally, especially transversely.

[0181] To make it clearer, Figures 6a-6e It will not be cut open.

[0182] Figure 6a The first step of the second process is shown, in which the lower substrate holder 1u is moved to one side, particularly the right side. The left alignment optics 6ul measures the left alignment mark 5ol of the upper substrate 2o. Simultaneously, the left positioning optics 7ul measures the left position mark 4ol of the left position mark field 3ol'.

[0183] Figure 6b The second process step of the second process is shown, wherein the lower substrate holder lu is shifted to the opposite side, specifically the left side. The right alignment optics 6ur measures the right alignment mark 5or of the upper substrate 2o. Simultaneously, the right positioning optics 7ur measures the right position mark 4or of the right position mark field 3or'.

[0184] Figure 6c The third step of the second process is shown, in which the lower substrate holder 1u is moved back to its original initial position. Simultaneously, the upper substrate holder 1o' moves to the right until the upper left alignment optics 6ol can freely observe the lower alignment mark 5ul of the lower substrate 2u through the opening 9. The position of the lower alignment mark 5ul relative to the left optical axis is stored.

[0185] Figure 6dThe fourth step of the second process is shown, in which the upper substrate holder 1o' moves to the left until the lower alignment mark 5ur of the lower substrate 2u can be freely observed through the opening 9 by the upper right alignment optics 6or. The position of the lower alignment mark 5ur relative to the right optical axis is stored.

[0186] Figure 5c and Figure 5d The prerequisite for the process steps in is that, based on... Figure 5b In step two of the process, the lower substrate holder has been moved back to its position so that the two alignment marks 5ul and 5ur are within the field of view of the alignment optics 6ol and 6or. If this is not the case for at least one of these alignment marks 5ul and 5ur, the lower substrate 2u must be repositioned accordingly, and steps three and four of the process must be repeated.

[0187] From this process step onwards, the substrate holder 2u is no longer allowed to be moved.

[0188] Figure 6e The fifth step of the second process is shown, in which the upper substrate holder 1o' is now moved back to its original position until the position marker fields 3ol', 3or' appear within the field of view of the lower positioning optics 7ul, 7ur. From this point onward, the upper alignment marks 5ol, 5or can be aligned with the lower alignment marks 5ul, 5ur by an automatic controller bringing the upper substrate holder 1o' to the correct position via position measurements of the position marks 4ol, 4or. This process is a fine-tuning process, which... Figures 8a-8b The alignment system for all types is described in more detail.

[0189] In the following process steps, the two substrates are brought close together and the actual bonding process between them is performed. These process steps will not be described further because they no longer involve the concept.

[0190] exist Figures 5a-6e The process described for Type 1 and Type 2 is based on the principle of aligning all alignment optics to the focal plane, but is unrelated to this idea. No further movement of the optics occurs after alignment.

[0191] In the case of the Type 3 alignment system, the situation is entirely different. Here, the lower alignment optics are designed such that they can only move in the z-direction, while the upper alignment optics can move in the x-direction, y-direction, and preferably also in the z-direction. Furthermore, the lower substrate holder can only move in the z-direction, while the upper substrate holder has degrees of freedom in the x-direction, y-direction, and preferably also in the z-direction, as well as about three rotational axes. Correspondingly, this idea also affects the process steps.

[0192] In the following figures, each figure shows a side view (left side) along the X direction and a front view (right side) along the Y direction.

[0193] To make it clearer, this time... Figures 7a-7e Cut it open.

[0194] The alignment optics 6ul, 6ur, 6ol, 6or and the positioning optics 7uv, 7uh can preferably all be positioned, rotated and controlled independently of each other.

[0195] Figure 7a The first step of the third process is shown. The upper substrate holder 10'' moves to the left. In particular, the left alignment optics 6ul moves upward in the z-direction until the left alignment optics have the left alignment mark 5ol of the upper substrate 2o in its field of view and depth of field. In particular, at least one positioning optics 7uv, 7uh also moves upward until at least one position mark 4o of one of the position mark fields 3ov, 3oh is visible. In this way, at least one position mark 4o of at least one of the position mark fields 3ov, 3oh can be associated with the left alignment mark 5ol. If the device is designed such that the alignment mark 5ol and the position mark fields 3ov, 3oh can already be detected in the depth of field, then the movement of the alignment optics 6u and the positioning optics 7uv, 7uh is of course unnecessary.

[0196] Figure 7bThe second step of the third process is shown. The upper substrate holder 10'' moves to the right. In particular, the right alignment optics 6ur moves upward in the z-direction until the right alignment optics have the right alignment mark 5or of the upper substrate 2o in its field of view and depth of field. In particular, at least one positioning optics 7uv, 7uh also moves upward until at least one position mark 4o of one of the position mark fields 3ov, 3oh is visible. It is conceivable that both positioning optics 7uv, 7uh have been positioned through the first process step. It is also conceivable that in the first process step, only one of the positioning optics 7uh, 7uv is connected to the left alignment optics 6ul, and therefore the corresponding second positioning optics must now be positioned. If this embodiment uses only one positioning optics 7uv or 7uh, then the positioning optics has been positioned through the first process step and now the second position mark 4o of the same position mark field 3ov or 3oh is measured. In this way, at least one other position mark 4o can be associated with the right alignment mark 5or. If the device is designed such that the depth of field is already capable of detecting the alignment mark 5or and the position mark fields 3ov and 3oh, then of course there is no need for the movement of the alignment optics 6ur and the positioning optics 7uv and 7uh.

[0197] Figure 7c The third step of the third process is shown. The lower substrate holder 1u moves upward. In particular, the upper left alignment optics 6ol moves simultaneously in several directions to bring the lower alignment mark 5ul of the lower substrate 2u into the field of view and depth of field.

[0198] Figure 7d The fourth step of the third process is shown. The upper substrate holder 10 moves to the left. In particular, the upper right alignment optics 6or moves simultaneously in several directions to bring the lower alignment mark 5ur of the lower substrate 2u into the field of view.

[0199] Figure 7e The fifth step of the third process is shown. The upper substrate holder 10 is aligned relative to the lower substrate holder 10, such that the upper alignment marks 5ol, 5or and the lower alignment marks 5ul, 5ur coincide as much as possible. Here, the movement of the upper substrate holder 10 is checked by at least one of the positioning optics 7uv and 7uh, wherein at least one of the position mark fields 3ov and 3oh is continuously read and evaluated. In particular, fine positioning is performed by pixels. Therefore, although the alignment marks 5ul, 5ur, 5ol, 5or are blocked by the respective opposing substrates and are no longer visible, the upper substrate 20 can be aligned relative to the lower substrate 2u.

[0200] Figure 8aThe image shows the state in which position mark 4 can be seen within the field of view of the positioning optics (not shown) (left image). Alignment mark 5 can be measured within the field of view of the alignment optics (not shown) (right image) at any point in time.

[0201] Figure 8b The image shows the state of position mark 4 within the field of view (left image) of the positioning optics (not shown). This position mark has been continuously shifted by the relative displacement of the substrate holder (not shown) until alignment mark 5 is in the desired position. For clarity, the desired position of alignment mark 5 has been selected such that it lies on the optical axis of the alignment optics (not shown). The measurement of position mark 4 can be achieved with pixel precision and is thus used for fine positioning.

[0202] List of reference numerals

[0203] 1o, 1o', 1o'', 1o''', 1u Substrate Holder

[0204] 2o, 2u substrates

[0205] 3ol, 3or, 3ol', 3or', 3o'', 3ov, 3oh position marker fields

[0206] 4, 4o, 4ol, 4or, 4oh, 4ov position markers

[0207] 5, 5ol, 5or, 5ul, 5ur alignment marks

[0208] 6ol, 6or, 6ul, 6ur alignment optical components

[0209] 7ul, 7ur, 7uv, 7uh positioning optical components

[0210] 8, 8o, 8u fixed components

[0211] 9 Opening

[0212] 10 Deformable elements.

Claims

1. An apparatus for aligning substrates (2o, 2u), comprising: - First substrate holders (lo, lo', lo'', lo''', lu) for accommodating first substrates (2o, 2u), wherein the first substrates (2o, 2u) have at least two alignment marks (5, 5ol, 5or, 5ul, 5ur). - Second substrate holders (lo, lo', lo'', lo''', lu) for receiving a second substrate (2o, 2u), wherein the second substrate (2o, 2u) has at least two other alignment marks (5, 5ol, 5or, 5ul, 5ur). - At least one alignment optics (6ol, 6or, 6ul, 6ur) for detecting the alignment marks (5, 5ol, 5or, 5ul, 5ur). Its features - The device further comprises: - At least one positioning optics (7ul, 7ur, 7uv, 7uh) for detecting position marks (4, 4o, 4ol, 4or, 4oh, 4ov), wherein at least one position mark is on the surface of the first substrate holder facing the second substrate holder, and wherein the area of ​​the first substrate holder where the position mark is located is not covered by the second substrate holder and is visible to at least one positioning optics. The first substrate holder and the second substrate holder are opposite to each other. The second substrate holder has a base surface narrower than that of the first substrate holder, and The alignment marks (5, 5ol, 5or, 5ul, 5ur) of the first substrate (2o, 2u) and other alignment marks (5, 5ol, 5or, 5ul, 5ur) of the second substrate (2o, 2u) can be aligned with each other according to the position marks (4, 4o, 4ol, 4or, 4oh, 4ov).

2. The apparatus of claim 1, wherein when one or more of at least two alignment marks (5, 5ol, 5or, 5ul, 5ur) of the first substrate (2o, 2u) are obscured by the second substrate (2o, 2u) for the at least one alignment optics (6ol, 6or, 6ul, 6ur) and / or when one or more of at least two other alignment marks (5, 5ol, 5or, 5ul, 5ur) of the second substrate (2o, 2u) are obscured by the first substrate (2o, 2u) for the at least one alignment optics (6ol, 6or, 6ul, 6ur), the alignment marks (5, 5ol, 5or, 5ul, 5ur) of the first substrate and the second substrate (2o, 2u) can be aligned with each other by the position marks (4, 4o, 4ol, 4or, 4oh, 4ov).

3. The apparatus according to any one of claims 1 to 2, wherein the position markers (4, 4o, 4ol, 4or, 4oh, 4ov) form a position marker field (3ol, 3or, 3ol', 3or', 3o'', 3ov, 3oh), wherein the orientations of the different position markers (4, 4o, 4ol, 4or, 4oh, 4ov) relative to each other are known.

4. The apparatus according to claim 3, wherein the position marks are arranged in a regular pattern.

5. The apparatus of claim 3, wherein the orientations of the different position markers in the position marker field (3ol, 3or, 3ol', 3or', 3o'', 3ov, 3oh) formed by the position markers (4, 4o, 4ol, 4or, 4oh, 4ov) relative to each other are known.

6. The apparatus according to any one of claims 1 to 2, wherein the position markers (4, 4o, 4ol, 4or, 4oh, 4ov) are formed by a plurality of fine positioning elements.

7. The apparatus of claim 6, wherein the fine positioning elements are irregularly arranged.

8. The apparatus according to any one of claims 1 to 2, wherein each position mark (4, 4o, 4ol, 4or, 4oh, 4ov) is formed differently, wherein the position mark has specific information content.

9. The apparatus of claim 8, wherein the information content can be detected by the positioning optics (7ul, 7ur, 7uv, 7uh).

10. The apparatus according to any one of claims 1 to 2, wherein the position markers (4, 4o, 4ol, 4or, 4oh, 4ov) have one or more of the following implementations: - QR code - Barcode - Geometric shapes - String, - Image.

11. The apparatus of claim 10, wherein the geometry is three-dimensional.

12. The apparatus of claim 10, wherein the string is a sequence of letters and / or a sequence of numbers.

13. The apparatus of claim 10, wherein the string is a binary code.

14. The apparatus according to any one of claims 1 to 2, wherein at least one of the first substrate holder and the second substrate holder (lo, lo', lo'', lo''', lu) and / or the at least one positioning optics (7ul, 7ur, 7uv, 7uh) is movable in at least two directions.

15. The apparatus of claim 14, wherein the two directions are the x-direction and the y-direction.

16. The apparatus according to any one of claims 1 to 2, wherein the position marks (4, 4o, 4ol, 4or, 4oh, 4ov) are laterally arranged next to at least one of the first substrate and the second substrate (2o, 2u), such that when the alignment marks (5, 5ol, 5or, 5ul, 5ur) of one substrate (2o, 2u) are blocked by the other substrate (2o, 2u) for at least one alignment optics (6ol, 6or, 6ul, 6ur), the alignment marks (5, 5ol, 5or, 5ul, 5ur) of the first substrate and the second substrate (2o, 2u) can be aligned with each other.

17. The apparatus according to any one of claims 1 to 2, wherein the position marks (4, 4o, 4ol, 4or, 4oh, 4ov) are arranged at the same height as the substrate surface of at least one of the first substrate and the second substrate (2o, 2u).

18. The apparatus according to any one of claims 1 to 2, wherein the positions of the alignment marks (5, 5ol, 5or, 5ul, 5ur) of the first substrate and the second substrate (2o, 2u) can be detected by the at least one positioning optics (7ul, 7ur, 7uv, 7uh) when the alignment marks (5, 5ol, 5or, 5ul, 5ur) of the first substrate and the second substrate (2o, 2u) are aligned with each other.

19. The apparatus of claim 18, wherein the positions of the alignment marks (5, 5ol, 5or, 5ul, 5ur) of the first substrate and the second substrate (2o, 2u) can be continuously detected by the at least one positioning optics (7ul, 7ur, 7uv, 7uh) while aligning the alignment marks (5, 5ol, 5or, 5ul, 5ur) of the first substrate and the second substrate (2o, 2u) with each other.

20. A method for aligning two substrates (2o, 2u) using the apparatus according to any one of claims 1 to 19, the method comprising at least the following steps: i) Fix the two substrates (2o, 2u) to one substrate holder (lo, lo', lo'', lo''', lu) in the first substrate holder and the second substrate holder. ii) Detect the alignment marks (5, 5ol, 5or, 5ul, 5ur) on the two substrates (2o, 2u). iii) Detect location markers (4, 4o, 4ol, 4or, 4oh, 4ov). iv) Align the alignment marks (5, 5ol, 5or, 5ul, 5ur) of the two substrates (2o, 2u) with each other according to the position marks (4, 4o, 4ol, 4or, 4oh, 4ov), wherein at least one position mark is on the surface of the first substrate holder facing the second substrate holder, and wherein the area of ​​the first substrate holder where the position mark is located is not covered by the second substrate holder and is visible to at least one positioning optics. The first substrate holder and the second substrate holder are opposite to each other. The second substrate holder has a base surface that is narrower than that of the first substrate holder.

21. The method of claim 20, wherein after step iii), the position of the alignment marks (5, 5ol, 5or, 5ul, 5ur) and / or the orientation of the alignment marks relative to each other can be determined.

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