Method and apparatus for bonding substrates together

Abstract

A method and apparatus for bonding substrates together.

Description

[Technical Field]

[0001] The present invention relates to a method and apparatus for bonding substrates, particularly wafers. During bonding, the substrates are oriented relative to one another, brought into contact with one another, and bonded together. For orientation, the substrates are held in a substrate receiving device, particularly a vacuum substrate holder, so that the substrate surfaces to be bonded are precisely oriented relative to one another before bonding. In this case, a bond that is as free from distortion and stretching as possible across the entire surface should be produced.

[0002] In the prior art, the upper and lower substrates are loaded in a bonding orientation, so that the bonding sides of the upper and lower substrates already face each other before bonding. This has the advantage that the bonding apparatus occupies little space, because the upper substrate holder does not need to be rotated, turned, or moved. However, the different holding forces acting on the upper and lower substrate holders result in different stresses being generated in the substrates to be bonded.

[0003] In U.S. Pat. No. 9,613,840, an upper substrate and a lower substrate are loaded in a joining orientation. The upper substrate is deformed using a deformation means, in particular a mechanical pin, which acts on the opposite side to the joining side, in particular based on its shape. The initiation of contact is influenced by deformation of the upper substrate in the center using the pin, while after contact, the upper substrate is released and spontaneously joins to the opposing substrate based on its own preload.

[0004] In U.S. Patent No. 9,613,840, at least one substrate is no longer secured to the receiving device during the bonding process. Furthermore, the upper and lower receiving devices are not identical in structure due to their different configurations, and therefore provide different stress patterns to the respective substrates due to loading or securing.

[0005] In U.S. Pat. No. 8,918,989, a fixing means is provided for at least partially pre-fixing the oriented substrate to the carrier substrate. Both substrates are loaded one above the other in a sequential, bonded orientation. During orientation, a spacing means is used to maintain the spacing between the substrate and the carrier substrate, after which a force-controlled actuator acting at the center acts on the substrate stack to fix the substrate. In U.S. Pat. No. 8,918,989, bonding or pre-bonding is performed without any pre-fixing of the upper substrate to the upper receiving device.

[0006] In U.S. Pat. No. 6,383,890, both substrates are loaded from above. By rotating the pivotally supported upper receiving device by 180°, both substrates are positioned parallel to each other for bonding in the bonding orientation. A pin penetrates the upper receiving device and initiates the bonding process by bending the center of the upper substrate. In this case, the upper substrate is released from the clamping. It is not envisaged that all features, in particular the clamping elements of the upper and lower substrate receiving devices, in particular the loading pins of the upper and lower substrate receiving devices, are symmetrically configured. Furthermore, different holding or clamping forces are provided.

[0007] In WO 2015 / 183197, the upper substrate receiving device is rotated 180° about its own axis for bonding. In this case, the upper substrate receiving device is moved between a substrate loading position and a substrate bonding position. The advantage of this is that the orientation of the substrate provided with the structure in the receiving device can be more easily controlled from the uncovered top surface.

[0008] It is not anticipated that all features of the upper and lower substrate receiving devices will be configured symmetrically, as these features will be configured differently due to the structure of the devices, and different retention forces will be provided in different patterns.

[0009] Substrates to be bonded, especially wafers, are often structured and coated with up to several layers of different materials. These pre-processing steps can generate mechanical stresses that can cause the wafers to warp in a free-form manner. This warping manifests itself, for example, as a tendency to warp, curvature, distortion, and / or local deformation. If one of the substrates to be bonded is not or is no longer fixed to a substrate receiving device during the bonding process, some of this stress will be incorporated into the bonding interface as strain.

[0010] The crystalline structure of the substrate material also determines whether the properties are isotropic or anisotropic, which can affect the bonding process. The mechanical properties of silicon (Si), for example, are anisotropic. Single-crystal silicon has different elastic moduli (elastic moduli) in different directions. This different stiffness causes the generated bond wave to travel at different speeds. This difference in stiffness is more pronounced when the substrates, especially the upper substrate, are released from the clamping mechanism during bonding. The directional dependency of the elastic modulus also makes other mechanical properties, especially the expansion coefficient, dependent on the direction.

[0011] In the semiconductor industry, substrates have been bonded to one another for several years by a so-called bonding process. Before bonding, these substrates must be oriented relative to one another as precisely as possible, and deviations occurring between them in the nanometer range are important. In this case, the orientation of the substrates relative to one another is mainly achieved via orientation marks. In addition to the orientation marks, other, particularly functional, elements can be provided on the substrates, and these elements must also be oriented relative to one another during the bonding process.

[0012] One of the biggest challenges during bonding is the bonding process itself, i.e., from the start of bonding until the contact surfaces of the substrates are completely in contact. In this case, the orientation of the two substrates relative to each other can change significantly compared to their previous orientation. Once the surfaces of the two substrates are bonded together, separation is theoretically possible again, but this is associated with high costs and the occurrence of defects. In the prior art, there are several methods and equipment that can be used to try to influence the bonding process.

[0013] During the bonding process, stress patterns can lead to distortion and defect generation. Substrates to be bonded, especially wafers, are often structured and coated with up to several layers of different materials. These pre-processing steps generate mechanical stresses that can cause the wafers to warp in a free-form manner. In addition to the mechanical stresses from the pre-processing steps, further stress patterns can occur when the substrates are loaded. Components of the receiving device that can affect the substrate shape and cause loading stresses include, among others, loading pins, fixing and support elements, and further surface features of the receiving device.

[0014] In this case, some of this stress will be incorporated into the bond interface as strain upon bonding, and the stresses may be relieved by additional defect formation, may cancel each other out, or may remain as residual stresses in the bonded stack.

[0015] Residual stresses are particularly strong in the case of thin substrates or thin substrate stacks. Backside-thinned substrates must be used and maintained in their original, preferably planar, shape.

[0016] It is therefore an object of the present invention to at least partially overcome, and in particular completely overcome, the drawbacks of the prior art. Among other things, it is an object of the present invention to provide an improved method and apparatus for bonding. It is also an object of the present invention to produce a bonded substrate stack with minimal residual stress.

[0017] The above-mentioned problem is solved by the features of the parallel independent claims. Advantageous developments of the invention are defined in the dependent claims. All combinations of at least two features described in the description, claims and / or drawings are also included within the scope of the invention. Where numerical ranges are given, values ​​lying within the stated limits are also to be considered as disclosed as boundary values ​​and should be claimable in any combination.

[0018] Surprisingly, it has been found that, in addition to the mechanical stresses already generated in the substrates in previous process steps, structural features of the substrate receiving device that come into direct contact with the substrates can compensate for or prevent new stress patterns, for example, during the process of loading the substrate into the substrate receiving device, thereby improving the bonding result. In the prior art, the stress patterns are different for the upper and lower substrates due to different behaviors. For example, different configurations of the upper and lower substrate receiving devices, particularly the substrate holder surfaces, fixing elements, and holding forces, generate different stress patterns in the substrates to be bonded.

[0019] When forces, especially gravity, act on a substrate resting on the loading pin or on the structures of the holding surface, asymmetric deformations occur that remain present during contact between the two substrates and / or during the bonding process, resulting in asymmetric propagation of the bonding wavefront and thus undesirable run-out effects.

[0020] Additionally, the loading of the upper and lower substrates in the bonding orientation necessarily results in different stress patterns that can also become incorporated together as strain at the bonding interface, especially if these different, asymmetric stress patterns cannot subsequently be offset.

[0021] The method and apparatus for bonding improves bonding results, among other things, through the combination of features proposed.

[0022] The present invention therefore provides a method for bonding substrates, the method comprising, inter alia, the following steps in the following sequence: i) providing a first substrate on a first substrate holder surface of a first substrate holder and a second substrate on a second substrate holder surface of a second substrate holder; ii) fixing the first substrate to the first substrate holder and the second substrate to the second substrate holder in a loaded state; iii) fixing the second substrate to the second substrate holder in a bonding position, such that the surfaces to be bonded of the first and second substrates face each other. and iv) bonding the first substrate to a second substrate, wherein in the loaded state the first substrate holder surface and the second substrate holder surface are disposed at the same angle relative to the Earth's gravitational force, and in the loaded state the first substrate holder surface and the second substrate holder surface are oriented in the same direction relative to the Earth's gravitational force, such that when the first substrate and the second substrate are secured together, the same holding force is applied to the first substrate and the second substrate, respectively.

[0023] In other words, the two substrates are provided under the same gravitational conditions with respect to the substrate holders, which are oriented in the same way relative to gravity, and the same holding force is applied to the substrates for fastening. This is particularly advantageous in that the same stresses can be generated in the substrates, which has a favorable effect on the bonding result. It is particularly preferred that the fastening elements provided on the respective substrate holders are arranged symmetrically with respect to the bonding interface in the bonding position. It is particularly preferred that the substrates or substrate holder surfaces are positioned symmetrically and parallel to each other so that the surfaces to be bonded face each other when positioned. Symmetrical positioning or orientation means that the fastening points, the holding forces at the fastening points, and the substrate holder mounting surfaces are congruent or mirror-symmetric in the plane formed between the substrates. In other words, all features that affect the stresses in the substrates in the loaded state are aligned.

[0024] In this case, the first and second substrates preferably have the same dimensions. In particular, they have the same weight. The first substrate holder surface is configured symmetrically, in particular axially symmetrically, with respect to the second substrate holder surface. Preferably, the substrate holder surfaces correspond to each other so that, in the loaded state, the mounting surfaces of the respective substrate holder surfaces are symmetrically arranged with respect to each other and so that, when joined, the opposing mounting surfaces are aligned. In this case, the substrate holder surface is in particular the surface of the substrate holder on which the substrate is mounted. The substrate holder surface may include, for example, a full surface with mounting pins, protrusions, or recesses for fastening means.

[0025] In the loaded state, the substrate holders or the substrate holder surfaces, and thus the substrates, are positioned in the same way with respect to the acting force of gravity. In this case, the substrate holder surfaces are oriented in the same direction with respect to gravity. In this case, for example, the substrate holder surfaces are both oriented upward or both oriented downward. In the loaded state, the substrates are not loaded from above and below, respectively, but are both loaded in the same way, so that gravity acts in the same way at the time of loading, and the same stress, particularly the same stress pattern, acts on both substrates even when the same holding force is applied.

[0026] In this case, the surface of the substrate to be bonded is not placed on the surface of the substrate holder, but faces away from the substrate holder. In this case, the substrate holder is preferably vertical or horizontal with respect to the gravitational force of the Earth. Preferably, the substrate holders arranged side by side have the same angle relative to the gravitational force of the Earth in the loaded state. In this case, slight differences in gravity due to misalignment and slight differences in the distance to the center of gravity can be ignored.

[0027] When the substrates are clamped, identical holding forces acting in the same manner on the substrates are provided. In this way, a corresponding stress pattern can be advantageously generated within the substrates, thereby improving the joining result. The holding forces are preferably maintained during the transition to the joining position.

[0028] The positioning may be performed arbitrarily and may include moving both substrate holders in any direction.

[0029] When substrates or stacks of substrates are bonded, the substrates to be bonded are loaded into corresponding receiving devices with the same orientation relative to the Earth's gravitational force, so to speak, in a minimally invasive manner, and held with a holding force that acts identically or symmetrically on both substrates. Different holding forces are typically provided here, since the substrates to be bonded must first be positioned on the lower substrate holder and then held in the upper substrate holder. A larger holding force typically acts on the upper substrate holder, since the weight of the fixed upper substrate must be additionally compensated for.

[0030] The symmetry preferably also applies to all further components of the substrate holder which may have an influence on the stresses in the substrate (mounting surfaces, kind of fixing elements, orientation marks, tubes, etc.) All components are preferably arranged axially symmetrically.

[0031] In a preferred embodiment of the bonding method, in the loaded state, the first substrate is placed on the first substrate holder surface, and the second substrate is placed on the second substrate holder surface. The term "placed" means that the first substrate and the second substrate are placed by their own weight on the identically oriented substrate holder surfaces, and theoretically, do not need to be fixed. In other words, the surfaces to be bonded are both oriented against gravity while the back surfaces of the two substrates are abutting the substrate holder surfaces. In this way, particularly advantageous stress-free loading can be achieved.

[0032] In a preferred embodiment of the bonding method, the angle is assumed to be a perpendicular angle. In other words, the same angle when the substrate holder surfaces are oriented relative to gravity is 90°. In this case, the substrate and the substrate holder surface are preferably planar. Therefore, the substrate is also oriented approximately parallel to gravity and thus to the center of gravity. In this way, particularly good bonding results can be achieved. Furthermore, slippage of the substrate can be prevented.

[0033] In a preferred embodiment of the bonding method, the same holding forces are provided in corresponding patterns on the first and second substrates during fixation in the loaded state, so that the patterns of the holding forces are aligned in a straight line at the bonding position. In other words, the opposing substrate surfaces are congruent with respect to the provided fixation patterns at the bonding position. That is, the same holding forces are provided at positions exactly opposite each other at the bonding position. Therefore, it is ensured that the stresses present in the substrates are of the same magnitude and positioned in the same way at the bonding position based on the fixation in the opposing regions of the substrate surfaces. Therefore, at the bonding position, the stress distribution in the first substrate is aligned with the stress distribution in the second substrate. Therefore, in the loaded state, the holding forces are provided, for example, in an axially symmetrical arrangement, so that simple rotation is sufficient for positioning.

[0034] In a preferred embodiment of the bonding method, the first substrate and the second substrate are fixed simultaneously and within the same time period. In other words, the holding force is applied within the same time and is performed simultaneously. In this case, the gradient of the holding force per unit time at the same location is preferably also the same. In this way, better bonding results can be achieved.

[0035] In a preferred embodiment of the bonding method, the positioning includes pivoting the second substrate holder by 180°. Preferably, pivoting the second substrate holder is performed so that the first substrate holder does not need to be moved. After positioning or after transition to the bonding position, it may be necessary to move the substrate holders closer together. Pivoting the second substrate holder by 180° about its axis of symmetry advantageously allows for a particularly simple and fault-free transition to the bonding position. After pivoting, the second substrate holder is preferably oriented strictly perpendicular to its orientation in the loaded state.

[0036] In this case, "towards each other" means that the substrate holder surfaces are oriented so as to face each other. In this case, the additional movement for the initial contact for bonding is carried out only by, inter alia, bringing the first and second substrate holder surfaces closer together or by bringing the first and second substrate holders closer together. In this case, the same holding force is preferably maintained, and the corresponding patterns are simply moved further towards each other. The orientation is preferably carried out only by pivoting.

[0037] In a further preferred embodiment of the bonding method, the positioning step involves rotating the first and second substrate holders toward each other by 90°. In this case, both substrate holders are rotated along their axes of symmetry or parallel central axes at the centers of the substrate holders. In this way, if the orientation relative to the Earth's gravitational force is perpendicular in the loaded state, the gravitational forces on the first and second substrates are the same after positioning. Particularly preferably, in the loaded state, the surfaces of the first and second substrate holders are oriented strictly perpendicular to gravity. Therefore, the bonding results can be improved in the case of bilateral rotation.

[0038] In a preferred embodiment of the joining method, it is assumed that the same holding force is maintained during joining. In this way, the same holding force is not only maintained during fixing and during the transition or positioning into the joining position, but also after the end of joining. In this way, residual stresses due to loading can be compensated for, improving the joining result.

[0039] The present invention further relates to an apparatus for bonding substrates, the apparatus comprising at least a first substrate holder having a first substrate holder surface, a first fastening means for fastening the first substrate to the first substrate holder surface, a second substrate holder having a second substrate holder surface, a second fastening means for fastening the second substrate to the second substrate holder surface, and a positioning means for positioning the second substrate holder relative to the first substrate holder, the apparatus being movable into a loaded state, wherein in the loaded state the first substrate holder surface and the second substrate holder surface are disposed at the same angle relative to the Earth's gravitational force, and wherein in the loaded state the first substrate holder surface and the second substrate holder surface are oriented in the same direction relative to the Earth's gravitational force, and the first fastening means and the second fastening means are configured to provide the same holding force for fastening in the loaded state.

[0040] In other words, the first and second fastening means act in the same manner on the first and second substrates. The device is configured so that the holding force provided by the first and second fastening means is the same. Particularly preferably, the fastening means are configured to provide the same holding force simultaneously and for the same period of time. In this case, the gradient of the holding force per unit time is preferably also the same for the fastening means, or the device is configured accordingly. Loading in the loaded state generates the same stress pattern in both substrates to be bonded. In this way, the bonding results are unexpectedly improved. The device can have a control unit configured to establish the respective conditions in the loaded state. The additional advantages and features of the bonding method described above also apply to the device.

[0041] In a preferred embodiment of the device for bonding substrates, the device is configured so that in the loaded state, the first and second substrate holder surfaces are arranged parallel and offset from one another. In this case, the center points of the substrate holder surfaces are offset from one another in terms of direction, among other things. Preferably, the first and second substrate holder surfaces are not aligned, but are arranged offset from one another from one another in the loaded state, so that they are spaced apart from one another at the same angle. In this way, particularly uniform loading can be achieved, which can improve the bonding result.

[0042] In a preferred embodiment of the device for bonding substrates, it is assumed that the second substrate holder can be pivoted from the loading state to the bonding position. The bonding position is advantageous in that the substrate holder surfaces are oriented parallel to and face each other, and therefore bonding can be performed simply by approximating them. In other words, in the bonding position, the substrates are already oriented and positioned. For this purpose, an approximation means can be provided. The simple pivoting from the loading state to the bonding position after fastening by the fastening means advantageously improves the bonding result. The device is preferably configured as a flip bonder.

[0043] In a preferred embodiment of the device for bonding substrates, it is provided that the positioning means comprises a swivel joint, in which case the positioning of the substrate holder about the swivel axis can be carried out particularly simply and precisely, which improves the bonding result.

[0044] In a preferred embodiment of the device for bonding substrates, it is assumed that the second fixing means is arranged axially symmetrically with respect to the first fixing means in the loaded state. In other words, after loading, i.e. in the bonding position, a position is obtained in which the stress patterns of the substrates are aligned, or the substrate holder surfaces and fixing elements are aligned. In this case, it is very particularly preferable that all features and components of both substrate holders that influence the stresses in the substrates are axially symmetrical.

[0045] The axial symmetry is preferably defined by a mirror axis extending through the pivot joint. In other words, in the loaded state, the first and second substrate holder surfaces, particularly the first and second fastening means, are arranged symmetrically about the pivot axis, so that after pivoting to the joining position, the arrangements of the fastening elements are aligned with each other. If the first and second substrate holders are arranged at different heights, offset next to each other, in the loaded state, the mirror axis extends through the plane formed by the pivot axis in the loaded state and the predetermined angle of the substrate holders. In either case, the patterns of the fastening elements correspond to each other, so that after transitioning to the joining state, the opposing substrate holder surfaces have identical and aligned stress patterns due to loading.

[0046] In a preferred embodiment of the device for bonding substrates, the first and second fixing means are electrostatic fixing means. Particularly preferably, the first and second fixing means are recessed into the substrate holder surface. Particularly preferably, the corresponding recessed grooves are arranged in a symmetrical pattern, similar to the first and second fixing means. If the electrostatic fixing means are configured to be entirely flat, their dimensions and arrangement are also aligned at the bonding position. In another embodiment, the fixing means are vacuum tracks, and in this case, their arrangement and other configurations are also configured to be congruent or corresponding at the bonding position.

[0047] In a preferred embodiment of the device for bonding substrates, the first and second substrate holders are assumed to form a fluid-tight bonding chamber in the bonding position. In this way, a bonding chamber can be formed between the first and second substrate holders by pivoting and, if necessary, by approaching. In this case, the substrates are positioned inside the bonding chamber. In this way, bonding can be advantageously performed in a protected space, which improves the bonding result. Furthermore, in the case of a particularly preferred fluid-tight bonding chamber, a vacuum can be applied or a fluid can be introduced into the bonding chamber before bonding.

[0048] In a preferred embodiment of the device for orienting substrates, the first and second clamping means are configured to provide the same holding force at least until they are moved into the bonding position. Particularly preferably, the same holding force is provided by the clamping means until immediately after the first and second substrates are bonded. In this way, advantageously, the stresses provided by the loading / fixing, at least in the loaded state, can remain the same in the patterns in the first and second substrates. In this way, the stresses can be compensated for, improving the bonding result.

[0049] A particularly important aspect of the present invention is that both substrates are accommodated in symmetrically constructed accommodation devices in the same manner before contact or bonding, so that the substrates are brought into contact and bonded with corresponding stress patterns. The loading of both substrates is performed, particularly under the same gravitational influence, e.g., from above. All features of the accommodation devices that may indirectly affect the substrate shape are configured symmetrically, preferably at the same time, and particularly preferably simultaneously, with respect to the first and second substrates, so that the first and second substrates exhibit identical, opposing stress patterns induced by the accommodation devices before bonding. In this case, at least one of the accommodation devices is preferably supported so that it can pivot. For this purpose, a fixing or holding force is provided so that, after pivoting, the surfaces to be bonded have the same stress patterns. Preferably, both substrates remain fixed in the accommodation devices during bonding. The symmetrical design of the accommodation devices minimizes the effects of loading stresses, thereby minimizing residual stresses after bonding. By clamping at least one of the substrates, and preferably both substrates, during bonding, further distortion is minimized.

[0050] The method for bonding reduces stress patterns that become incorporated into the bond interface as strain during bonding. The corresponding relaxation of the stress patterns minimizes residual stresses even after release of the substrate stack.

[0051] The underlying idea is that before contacting or bonding, both substrates are accommodated in a symmetrically constructed accommodation device in the same way, so that stresses in the substrates caused by accommodation and loading into the accommodation device are minimized, and the substrates come into contact and are bonded with corresponding stress patterns. In the following, the words stress, load, and stress are used synonymously. A further important aspect is that after contacting and during bonding, the substrates remain fixed in the accommodation device, so that corresponding stress patterns cancel each other out as much as possible, thereby achieving a reduction in residual stresses and thereby minimizing distortions.

[0052] A method and apparatus for bonding a first substrate and a second substrate with their facing contact surfaces, comprising, inter alia, the following steps in the following sequence: - accommodating the first substrate on a first receiving surface of a first receiving device, the loading being performed from above; a step of accommodating a second substrate on a second accommodating surface of a second accommodating device, the loading being performed from above; - attaching the substrate to the receiving surface by means of a fastening element; rotating the pivotally supported first and / or second receiving devices, thereby orienting both substrate surfaces to be bonded symmetrically relative to each other; Orienting the substrate; bonding the substrates by bringing them into contact with each other; wherein the first and second containment devices have a symmetrical configuration of all components, and wherein the substrate remains fixed to the first and / or second containment devices after contact and during bonding.

[0053] The two receiving devices or substrate holders can be rotated about any axis and then translated by X / Y / rotation into coordinated symmetrical positions.

[0054] What is important is that both substrates are loaded in a symmetrical orientation with the same gravitational influence on the first and second receiving devices, where, for bonding, preferably one receiving device with the substrates is turned 180° upside down or both receiving devices with the substrates are rotated 90° relative to each other so that they face symmetrically.

[0055] The components of the first and second storage devices, which are constructed symmetrically with respect to the tilting axis and / or the mirror axis between the first and second storage devices, include, inter alia, loading pins, fixing and support elements, and further possible characteristic surface features of the storage devices.

[0056] The loading pins, preferably three loading pins, are arranged symmetrically in a circle on the same radius in both receiving devices. When the substrates are loaded from above onto the loading pins in the first receiving device and the second receiving device, respectively, the substrates bend, for example, due to the influence of gravity. After the substrates are received on the receiving surfaces of the receiving devices, a loading stress or stress pattern remains in the fixed substrate. Due to the symmetry of the components of the receiving device, the stress patterns in the first substrate and the second substrate are also symmetric. This minimizes or preferably eliminates the effect of gravity on the load stress of the substrate, because the effects on both substrates can be canceled out due to symmetry after contact.

[0057] Therefore, the stress patterns in both substrates are symmetrical along the bond interface. After the bonded substrate stack is released, both substrates can relieve any residual stresses that are still present by relaxation in the same way, thereby minimizing the residual stresses.

[0058] substrate The first substrate and / or the second substrate are advantageously radially symmetrical. The substrates can have any desired diameter, but the substrate diameter is in particular 1 inch, 2 inches, 3 inches, 4 inches, 5 inches, 6 inches, 8 inches, 12 inches, 18 inches, or more than 18 inches. The thickness of the first substrate and / or the second substrate is between 1 μm and 2000 μm, advantageously between 10 μm and 1500 μm, and more advantageously between 100 μm and 1000 μm. In particular embodiments, the substrate can also have a rectangular shape or at least a shape different from a circular form. Preferably, wafers, particularly preferably circular wafers, are used as substrates.

[0059] Containment device The containment device allows the substrate to be supported and fixed securely and planarly, for example by applying a vacuum between the substrate and the containment device, by mechanical clamping, by electrostatic charging, or by other controllable chemical-physical adhesion properties.

[0060] In this case, an electrostatic receiving device is preferably used to receive and hold the substrate. The bonding device or embodiments of the bonding device are able to handle any substrate regardless of its diameter.

[0061] In this case, electrodes are used to generate an electrostatic holding force for fixing the substrate, particularly preferably in an electrostatic holding device. In this case, the substrate is fixed to a holding surface or substrate holder surface. The holding surface is a surface of the holding device that is configured to fix the substrate, preferably a planar surface, and this surface is assembled as a component of the substrate holder. In the following, flatness is used as a measure of the perfection of a flat surface (a mathematically ideal plane).

[0062] Planarity refers to the structure of a surface that lies between two ideally flat surfaces. The distance between the two flat surfaces defines the tolerance. Deviations from a flat surface are caused by macroscopic and / or microscopic surface defects. This deviation can also be defined as waviness and roughness. Surface waviness may be described as periodic rises and falls of the surface, especially in the millimeter and micrometer range. Roughness, on the other hand, is rather a non-periodic phenomenon in the micrometer and / or nanometer range.

[0063] To deal with the different deviations from an ideal surface, the term roughness is used in the following specification as a synonym for the superposition of all such effects. Roughness can be expressed as the average roughness, the squared roughness, or the mean roughness depth.

[0064] The calculated values ​​for the average roughness, the squared roughness, and the average roughness depth are generally different even when the measurement distance or area is the same, but are within the same order of magnitude. Therefore, the following numerical ranges for roughness should be understood to refer to values ​​of either the average roughness, the squared roughness, or the average roughness depth.

[0065] In a preferred embodiment, the electrostatic holding device or the substrate holder with electrostatic clamping means has a particularly planar holding surface to electrostatically press the substrate and ensure a very stable hold. The electrostatic attraction distributes the holding force evenly across the entire surface. The planarity of the holding device is better or more precise than the thickness variations and nanotopography of the substrate. In this case, the substrate may already have mechanical stresses from previous process steps, which may cause deformation if not clamped.

[0066] Substrates with wedge errors are not a problem for the receiving devices in the prior art. The wedge errors can be compensated for. Higher order thickness variations (e.g., center-to-edge, quadrant, etc.) are more problematic. Substrates with high flatness and curvature requirements, such as reflective masks, require a holding surface with high flatness, because otherwise defects such as image positioning errors and overlay errors (distortion) would occur. To that extent, a means for compensating for the wedge errors in connection with the bonding device is preferred.

[0067] The planarity of the retention surface of the electrostatic immobilization means is less than 1000 nm, preferably less than 200 nm, more preferably less than 50 nm, and most preferably less than 1 nm (difference between the highest and lowest points of the surface or retention surface).

[0068] In particular, nanotopography is an essential parameter for surface quality. Local (abrupt) non-planarity should be particularly avoided. In this case, the roughness is less than 100 nm, preferably less than 10 nm, more preferably less than 1 nm, and most preferably less than 1 Angstrom. Roughness is in particular a change in planarity of less than 1 nm / μm, more preferably less than 1 Angstrom / μm.

[0069] For structures in the nm range and for precise overlay, the reproducibility of the planarity of the substrates to be bonded is of great importance. The holding force of ultra-flat electrostatic clamping means, in particular with planarly configured holding surfaces, makes it possible to conformally flatten the substrates.

[0070] Both substrates are preferably loaded from above, i.e., perpendicular to gravity. The backsides of the substrates are attached to the holding surface by loading pins and fixed by electrostatic force. In this case, the substrates are fixed with high positioning accuracy and high holding force. The electrodes are particularly preferably recessed or embedded relative to the substrate holder surface and may be configured as unipolar or bipolar. The electrode configuration is symmetrical with respect to the axes of both substrates or with respect to the bonding interface.

[0071] What is important is that both substrates are loaded in symmetrical orientations or directions with the same gravitational influence on the symmetrically configured first and second substrate holder surfaces, where for bonding, one receiving device with the substrates can be rotated 180° upside down and positioned directly above the lower receiving device if necessary, or both receiving devices with substrates can be rotated 90° relative to each other so that they are also facing symmetrically.

[0072] Components of the first and second storage devices that are constructed symmetrically with respect to the tilting axis and / or the mirror axis between the first and second storage devices include, inter alia, loading pins, fixing and support elements, and further surface features of the storage devices.

[0073] If the receiving device or the substrate holder has a loading pin, a hole is necessarily provided in the substrate holder surface. The hole in which the loading pin moves or the loading pin itself is preferably provided with a seal. In this case, the position of the loading pin, the opening of the loading pin, the diameter of the opening of the loading pin, and the seal are configured identically and symmetrically in both receiving devices. The symmetrical features face each other after rotating one receiving device (180°) or after rotating both receiving devices (90°). The receiving devices are configured with axial symmetry and / or mirror symmetry, depending on whether one receiving device or both receiving devices are tilted or rotated. If the joining device or the joining device has recesses, for example for measuring means, these recesses are preferably also configured identically and symmetrically in both receiving devices.

[0074] Further features, such as patterns, structures or structuring provided on the holding surfaces, are also particularly preferably configured identically and symmetrically on both receiving devices.

[0075] The surface on which the fixing is performed can also be provided with patterns, grooves, protrusions, pins, or any other topography or surface structuring. These grooves can be, for example, linear, circular, or arbitrarily shaped. Any combination is also possible, for example, grooves and protrusions. The selected topography can further reduce the contact surface in order to obtain the smallest possible receiving surface.

[0076] In a preferred embodiment, it is envisioned that the ultra-flat electrostatic substrate holder is configured with symmetrically configured grooves that extend beyond the substrate edge to prevent air cushioning and "floating" of the wafer after loading (before clamping). The grooves are sized and distributed to allow ambient gas to escape. The grooves may be, for example, micro-grooves.

[0077] In a further embodiment, the electrostatic containment device is envisaged to have symmetrically configured protrusions to reduce the risk of contamination of the backside of the substrate, in which case the substrate holder surface may be formed at least in part by the surface of the protrusions.

[0078] Electrostatic attraction not only distributes the holding force evenly over the entire surface, but also improves heat exchange and reduces wear. Electrostatic fastening elements or means are therefore preferred. In this case, a material with a minimal coefficient of thermal expansion is preferably selected for the receiving device (thermal invariance).

[0079] In addition to material selection, surface smoothness is also achieved by machining, which minimizes the coefficient of friction of the holding surface against the substrate.

[0080] Not only are the external features of the first and second storage devices constructed symmetrically and identically with respect to the tilt axis and / or the mirror axis between the first and second storage devices. The first and second storage devices are also (almost) identical as a whole, and therefore both storage devices preferably have the same thickness and are constructed from the same components and materials. Particularly preferably, the first and second composites, each consisting of the substrate and the storage device or substrate holder, have the same mechanical stiffness.

[0081] The thickness of the containment device is selected so that the overall stiffness of the containment device, including the substrate, is not dominated by the anisotropic Young's modulus (elastic modulus) of the substrate.

[0082] The preferred ultra-flat electrostatic containment device may be used in vacuum, high vacuum, and / or ultra-high vacuum equipment. The electrostatic containment device may be used at ambient pressure under a gas atmosphere, especially an inert gas atmosphere.

[0083] In preferred embodiments, it is envisaged that the substrate and / or containment device are movable in at least three degrees of freedom, preferably at least four degrees of freedom, more preferably at least five degrees of freedom, and most preferably a total of six degrees of freedom, thereby enabling improved mobility of the substrate and / or containment device.

[0084] The Z direction or Z axis extends perpendicularly as a surface normal to the holding surface of the receiving device in the loaded position, while the X and Y directions or X and Y axes extend perpendicularly to each other and parallel to or within the holding surface of the receiving device.

[0085] Rotation around the X axis is represented by r, rotation around the Y axis by q, and rotation around the Z axis by j.

[0086] In another preferred embodiment, it is envisaged that the positioning system, the fixing system and the movement system are configured with a coarse drive and a fine drive for at least one degree of freedom, which advantageously allows the movement to be set precisely.

[0087] In another preferred embodiment, the receiving device has a central open-loop and / or closed-loop control unit for open-loop and / or closed-loop control of the movements and / or sequences, in particular the clamping of the substrate, and the position of the receiving device in the loaded state. In this case, the receiving device or the substrate holder preferably has at least one sensor for measuring influencing factors, in particular at least one distance sensor and / or position sensor. These sensors are also positioned symmetrically and constructed identically.

[0088] Bonding equipment For the joining, joining means are provided for joining and / or pre-joining and / or temporary joining. The words joining, pre-joining and temporary joining are used synonymously.

[0089] All embodiments of the apparatus for bonding can be operated in a low vacuum, more preferably in a high vacuum, even more preferably in an ultra-high vacuum, in particular at pressures below 100 mbar, preferably below 0.1 mbar, more preferably below 0.001 mbar, even more preferably below 10e-5 mbar, and most preferably below 10e-8 mbar.

[0090] It is important for the bonding device to load both substrates in a symmetrical orientation and with the same gravitational influence on the first and second receiving devices or substrate holders. The substrates to be bonded are preferably loaded from above. In this case, it is particularly preferable for at least one of the receiving devices to be pivotally supported. For bonding, one receiving device with the substrates is rotated 180° upside down, or both receiving devices with the substrates are rotated 90° relative to each other so that they face symmetrically. If one receiving device with the substrates is rotated 180° upside down, a rotational movement or a combination of a rotational movement and a translational movement is conceivable. The receiving devices can be rotated around any axis. Thus, the 180° rotation of one receiving device with the substrates can be performed around a mirror axis in the XY plane of the receiving device or as a rotational movement via a swivel joint.

[0091] The apparatus allows for high precision adjustment of the clamped substrates for precise orientation. The containment device is configured to bring the substrates into close proximity and contact with each other.

[0092] Bonding Process or Bonding The substrates are oriented relative to one another before the bonding process. Preferably, the orientation is performed by an orientation facility based on orientation marks. After both substrates have been oriented relative to one another, contacting is performed.

[0093] When joining two substrates, the step of bringing the oriented contact surfaces of both opposing substrates into contact is particularly important, since increasingly precise alignment accuracies or offsets are required, such as less than 50 μm, in particular less than 1 μm, preferably less than 250 nm, even more preferably less than 150 nm, and most preferably less than 50 nm. In the case of such orientation accuracies, many influencing factors must be taken into account.

[0094] When the substrates are brought into contact with each other and lowered, errors can occur, which can add up and make it impossible to maintain a reproducible adjustment precision, which can lead to a large number of rejects.

[0095] In a first preferred embodiment, after contacting, both substrates remain fixed in the first and second containing devices or substrate holders, respectively, during bonding.

[0096] If both substrates remain fixed in their respective containment devices during bonding, the total thickness variation (TTV) and stress patterns of the substrates have a smaller effect on the bonding result. In this case, a parallel, spontaneous (1:1) bond of both substrates fixed in the containment device is achieved, and no deformation of the substrates occurs at the bonding front. Bonding is preferably performed in high or ultra-high vacuum.

[0097] The bonding process is comprised, inter alia, of force and / or temperature influences. The bonding force is, inter alia, greater than 0.01 kN, preferably greater than 0.1 kN, even more preferably greater than 1 kN, most preferably greater than 10 kN, and very most preferably greater than 100 kN. The corresponding pressure range is obtained by normalizing the bonding force to the surface of the substrate.

[0098] The bonding temperature is especially lower than 200° C., preferably lower than 150° C., even more preferably lower than 100° C., most preferably lower than 50° C., and very most preferably at room temperature.

[0099] In a second embodiment, after contact, in particular the second upper substrate remains fixed to the receiving device during bonding, which results in less deformation of the upper substrate at the bonding front due to the higher stiffness of the fixed substrate.

[0100] In a third embodiment, after contacting, the first substrate and / or the second substrate, among others, remain fixed in the containment device during bonding. By fixing at least one of the substrates during bonding, distortion is minimized.

[0101] Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments, taken in conjunction with the drawings. [Brief explanation of the drawings]

[0102] [Figure 1a] FIG. 1 is a cross-sectional view showing a first embodiment of a joining device. [Figure 1b] 1b shows a plan view of the first and second substrate holders of the first embodiment of the apparatus according to FIG. 1a; FIG. [Figure 2a] FIG. 2 shows a plan view of the first and second substrate holders of the first embodiment of the apparatus with a first axis of rotation AA. [Figure 2b] 1 shows a plan view of the first and second substrate holders of the first embodiment of the apparatus with a second axis of rotation BB. FIG. [Figure 3a] 1 shows a cross-sectional view of a first embodiment of the device with a mechanically configured hinge at the axis of symmetry with loading pins of a first receiving device and a second receiving device in a loaded state. FIG. [Figure 3b]1 is a cross-sectional view of a first embodiment of the device with a mechanically configured hinge at the axis of symmetry after the first and second substrates have been loaded onto the loading pins. FIG. [Figure 3c] FIG. 1 is a cross-sectional view of a first embodiment of the device with a mechanically configured hinge at the axis of symmetry after the first and second substrates have been accommodated in the first and second substrate holders. [Figure 4] 1 is a cross-sectional view showing the apparatus in a loaded state and in a bonding position before the first and second substrates are bonded. FIG. [Figure 5a] 1 is a cross-sectional view showing the apparatus in a first method step of an exemplary method for bonding. [Figure 5b] 4 is a cross-sectional view of the device during a second method step. FIG. [Figure 5c] FIG. 4 is a cross-sectional view of the device in a third method step. [Figure 5d] FIG. 10 is a cross-sectional view of the device in a fourth method step. [Figure 5e] FIG. 10 is a cross-sectional view of the device in a fifth method step. [Figure 5f] FIG. 10 is a cross-sectional view of the device in a sixth method step. [Figure 6a] 3A and 3B are cross-sectional views of a third embodiment of the device in a first method step. [Figure 6b] 4A and 4B are cross-sectional views of a third embodiment of the device during a second method step. [Figure 6c] 4A and 4B are cross-sectional views of a third embodiment of the device during a third method step. [Figure 7a] 10 is a cross-sectional view of a fourth embodiment of the device in a first method step. FIG. [Figure 7b] 10 is a cross-sectional view of the fourth embodiment of the device in a second method step. FIG. [Figure 7c] FIG. 10 is a cross-sectional view of a fourth embodiment of the device in a third method step. [Figure 8a]5A and 5B are cross-sectional views of a fifth embodiment of the device in a first method step. [Figure 8b] 10 is a cross-sectional view of a fifth embodiment of the device in a second method step. FIG.

[0103] In the drawings, the same components or components having the same functions are given the same reference numerals.

[0104] 1a shows a schematic cross-sectional view, not to scale, of a first embodiment of a first receiving device 1 and a second receiving device 2, in which the movement of the second receiving device 2 is shown in simplified form. Both substrates 3, 4 are loaded from above in the same way. The structural features of the receiving devices 1, 2, such as the substrate fixing elements 5, the openings for the loading pins 6, and further surface features 7 of the receiving devices, are configured symmetrically, so that after the second receiving device is rotated, the first receiving device 1 and the second receiving device 2 face each other in a mirror-symmetrical manner.

[0105] The fixing elements 5 are used to fix the substrates 3, 4 to the receiving devices 1, 2. In a particularly preferred embodiment, the substrates 3, 4 are fixed electrostatically.

[0106] FIG. 1b shows a plan view of the first and second receiving devices 1 and 2 of the first embodiment of the device according to FIG. 1a.

[0107] Both substrates 3, 4 are loaded from above in the same manner. All features 5, 6, 7 of the receiving devices 1, 2 that may directly or indirectly affect the substrate shape are configured symmetrically with respect to the first substrate 3 and the second substrate 4, respectively, so that the first substrate 3 and the second substrate 4 will exhibit the same stress pattern induced by the receiving devices before bonding. These features include, among others, the substrate fixing elements 5, openings 6 for loading pins, and further surface features 7 of the receiving devices, such as openings for measuring devices, sensors, or tracks.

[0108] It is important for the device that both substrates 3, 4 are loaded in a symmetrical orientation and with the same gravitational influence on the first receiving device 1 and the second receiving device 2. Both substrates 3, 4 are loaded from above in their respective receiving devices (loading position, loaded state).

[0109] In this case, at least one of the receiving devices 1, 2 is supported so that it can be pivoted, so that after the substrates 3, 4 have been loaded, it is moved into a joining position so that the substrate surfaces to be joined face each other.

[0110] Figure 2a shows a plan view of a first storage device 1 and a second storage device 2 of a first embodiment of the device with a first pivot axis AA. In this first embodiment according to Figure 2a, the second storage device 2 is moved relative to the first storage device 1 by a rotational movement via a pivot joint (10, not shown) with the pivot axis AA.

[0111] The loading pins and the openings 6 for the loading pins provided on the holding surfaces of the receiving devices 1, 2 are arranged symmetrically on the same radius in both receiving devices 1, 2.

[0112] FIG. 2b shows a plan view of the first and second receiving devices 1, 2 of the second embodiment of the device with a second axis of rotation BB.

[0113] Here, for bonding, one of the containers with the substrates is rotated 180° upside down (axis AA or BB), or both containers with the substrates are rotated 90° relative to each other so that they face symmetrically. If one of the containers with the substrates is rotated 180° upside down, a rotational movement or a combination of a rotational movement and a translational movement is considered. The containers 1 and 2 can be rotated around any axis. Therefore, the 180° rotation of one of the containers with the substrates can be performed around a mirror axis in the XY plane of the containers, or as a rotational movement via a swivel joint.

[0114] 3a-3c show cross-sectional views of a first embodiment of the device, with a mechanically configured hinge 10 at the axis of symmetry or pivot axis AA. Initially, both chamber sections 12, 13 are open as shown in FIGS. 3a-3c. In the first process step according to FIG. 3a, the loading pins 8 of the first and second receiving devices 1, 2 are in the loading position. In the second process step according to FIG. 3b, the first and second substrates 3, 4 are loaded onto the loading pins 8 of the receiving devices 1, 2. The loading of both substrates 3, 4 is performed under the same gravitational influence, i.e., from above. The backsides of the substrates 3, 4 are attached to the holding surfaces of the receiving devices 1, 2 by the loading pins 8 and fixed by electrostatic forces. In this case, the substrates 3, 4 are fixed with high positioning accuracy and high holding force. The electrodes are preferably embedded in the receiving devices 1, 2 and may be unipolar or bipolar. The electrode configuration is symmetrical about the axes of both substrates 3,4.

[0115] The receiving devices or substrate holders 1, 2 are positioned and loaded in such a way that before contact or bonding, both substrates 3, 4 are received in the symmetrically constructed receiving devices 1, 2 in the same way, so that the substrates come into contact and are bonded together in zones with corresponding stress patterns 9. The areas with stress patterns 9 are caused, for example, by contact with the loading pins 8 and by deformation of the wafers between the loading pins 8 due to gravity.

[0116] In a third process step according to FIG. 3 c the first substrate 3 and the second substrate 4 are received in a receiving device and fixed by means of fixing means 5 .

[0117] 4, when the substrates 3, 4 rest solely on the loading pins 8, gravity causes a change relative to a flat surface, in which the corresponding regions of the first and second substrates with stress patterns are lifted in the open pivoting device due to the loading of the substrates onto the symmetrically configured loading pins. This change in contact area 9 is symmetric for both substrates 3, 4 in the bonding device 11, so that during or after bonding, the corresponding stress patterns are located in regions 9' one above the other. That is, the substrate stack has identical stress patterns symmetrically about the bonding interface.

[0118] In this case, at least one of the receiving devices 1, 2 is supported so as to be pivotable. The means for moving the second chamber section 13 relative to the first chamber section 12 consists in implementing a rotational movement between the chamber sections 12 and 13 via a pivot joint 10 according to Fig. 5b.

[0119] 5a to 5f show process steps in a first embodiment of a method and apparatus for bonding 11, preferably permanently bonding, especially fusion bonding, a first substrate 3 and a second substrate 4, the apparatus comprising: a) a joining chamber 11 consisting of a first chamber section 12 and a second chamber section 13; b) a receiving device 1, 2 for receiving and fixing substrates 3, 4, the receiving device 1, 2 being configured to bring the substrates into close proximity and contact with each other; It has.

[0120] For the time being, both chamber sections 12, 13 are open as shown in Figure 5a and the substrates 3, 4 are electrostatically clamped, in this case using electrodes in the electrostatic holding device to generate an electrostatic holding force to clamp the substrates.

[0121] The ultra-flat electrostatic holding devices 1, 2 have a specially designed planar holding surface to electrostatically press the substrates 3, 4 and ensure a highly stable hold. The electrostatic attraction distributes the holding force evenly across the entire surface. The planarity of the holding devices 1, 2 is better than the thickness variations and nanotopography of the substrates 3, 4. In this case, the substrates 3, 4 may already have mechanical stresses from previous process steps, which can cause deformation if not clamped.

[0122] After the substrates 3, 4 are loaded and fixed, the joining chamber 11 is closed according to the embodiment of FIG. 5b by pivoting the second chamber section 13 about the pivot joint 10. A motorized drive (not shown) can be provided for this purpose. After pivoting the second chamber section 13, according to FIG. 5c, the peripheral wall 12u of the first chamber section 12 rests on the peripheral wall 13u of the second chamber section 13. Sealing is achieved via a ring seal 14 provided on the upper surface of the peripheral wall 12u of the first chamber section 12.

[0123] The bonding device 11 can advantageously be operated in a vacuum or at ambient pressure under an inert gas. The substrates 3, 4 are initially precisely adjusted for accurate orientation and are kept separated during the vacuum process according to FIG. 5c. Preferably, orientation is performed by an orientation fixture based on orientation marks. Adjustments and approaches are known to those skilled in the art and will not be described in detail.

[0124] After both substrates have been oriented, contacting is carried out inter alia. In the next process step according to Fig. 5d, the second upper substrate 4 with the receiving device 2 is translated by the moving device 15 and the spacing changing means 16 towards the first lower substrate 3 for bonding inside the bonding chamber 11. The approach and adjustment are carried out in a controlled manner.

[0125] In order to be able to precisely control the movement of the second upper substrate 4, embodiments of the device preferably include at least one measuring device for measuring the position of the second upper substrate 4.

[0126] In the bonding method according to Figures 5a to 5f, the substrates 3, 4 are placed flat on top of each other. For structures in the nm range and for precise overlay, the reproducibility of the planarity of the substrates 3, 4 to be bonded is of great importance. The holding force of the ultra-flat electrostatic holding devices 1, 2, which have a particularly planarly configured holding surface, makes it possible to conformally flatten the substrates 3, 4.

[0127] In a first preferred embodiment, after contacting, both substrates 3, 4 remain fixed in the first and second receiving devices 1, 2, respectively, during bonding. If both substrates 3, 4 remain fixed in their respective receiving devices 1, 2 during bonding, the total thickness variation (TTV) and stress patterns of the substrates 3, 4 have a smaller influence on the bonding result. In this case, a parallel and spontaneous (1:1) bonding of both substrates 3, 4 fixed in the receiving devices is achieved, and no deformation of the substrates 3, 4 occurs at the bonding front.

[0128] In a second, less preferred embodiment, after contact, in particular the second upper substrate 4 remains fixed to the receiving device 2 during bonding. If the second upper substrate 4 remains fixed to the receiving device 2 during bonding, less deformation of the upper substrate 2 occurs at the bonding front due to the higher stiffness of the fixed substrate 2.

[0129] The underlying idea is that before contacting or bonding, both substrates 3, 4 are received in the same way in the symmetrically constructed receiving devices 1, 2, so that stresses in the substrates caused by receiving and loading into the receiving devices 1, 2 are minimized and the substrates 3, 4 are contacted and bonded with a corresponding stress pattern. By fixing the substrates 3, 4 in the symmetrically constructed ultra-flat electrostatic receiving devices 1, 2 during bonding, distortions at the bonding interface are further minimized.

[0130] In one embodiment, the receiving device 1, 2 is configured in such a way that the temperature of the substrates 3, 4 can be regulated, inter alia, in part by heating means.

[0131] The application of pressure causes the substrate surfaces to approach a boundary layer along the contact surface.

[0132] Before bonding, especially before orientation, the substrates can be pre-treated if necessary. Examples of pre-treatments are plasma treatment or amorphization of at least one of the two substrate surfaces. The bonding chamber and the process chamber for amorphization or plasma treatment can be part of a (evacuated) cluster facility.

[0133] Figure 5e shows the finished bonding process. The substrates 3, 4 are now in full contact with each other and the bonding process is complete. After the upper clamping is stopped, the second upper receiving device 2 inside the bonding chamber 11 is translated upwards by the moving device 15 and the spacing change means 16 back to the position according to Figure 5c. The substrate stack 17 remains in the first lower receiving device 1.

[0134] As shown in Figure 5f, the bonding device 11 can be opened again by rotational movement between chamber section 12 and chamber section 13 via the pivot joint 10 of the second chamber section 13, and the substrate stack 17 can be removed after the first lower receiving device has been released. By releasing the bonded stack 17 from the substrate holder, stresses in the substrates can be reduced as well. This relaxation process minimizes residual stresses.

[0135] In this case, at least one of the accommodation devices 1 and 2 is supported so as to be rotatable. In this case, the accommodation devices 1 and 2 can rotate around any axis. Therefore, a 180° rotation of one of the accommodation devices with the substrate may be implemented not only as a rotational movement via a swivel joint as shown in Figures 5a to 5c, but also as a rotation around a mirror axis in the XY plane of the accommodation devices 1 and 2.

[0136] A further solution is to translate one chamber section towards or away from the other chamber section after rotation. This can be achieved, for example, by a lifting cylinder. Furthermore, lateral guides can be additionally provided. A combination of rotational and translational movement, for example, by the kinematics of a four-bar linkage, is also conceivable.

[0137] In a further embodiment according to Figures 6a-6c, both receiving devices 1, 2 are positioned one on top of the other, so that both substrates 3, 4 are loaded as shown in Figure 6a, with the gravitational influence on the first receiving device 1 and the second receiving device 2 being the same. After the substrates 3, 4 are fixed, the second, upper receiving device 2 with the fixed substrate 4 is rotated upside down by 180° about its own rotation axis BB according to Figure 6b. After the rotation, both receiving devices 1, 2 are positioned mirror-symmetrically with respect to each other, so that all features of the receiving devices 1, 2, such as the fixing elements 5, the openings 6 for the loading pins, and the further surface features 7, are positioned symmetrically.

[0138] In a further embodiment according to Figures 7a to 7c, both receiving devices 1, 2 are located next to each other, so that also in this embodiment both substrates 3, 4 are loaded as in Figure 7a, with the influence of gravity being the same on the first receiving device 1 and the second receiving device 2. In this case, a combination of rotational and translational movements is performed so that the first receiving device 1 and the second receiving device 2 face symmetrically.

[0139] The two storage devices 1, 2 can be rotated around any axis, and then the two storage devices 1, 2 can be moved into adjusted symmetrical positions by X / Y / Z translation (and rotation).

[0140] In a preferred embodiment, it is envisaged that the substrate and / or the containment device 1, 2 are movable in at least three degrees of freedom, preferably at least four degrees of freedom, more preferably at least five degrees of freedom, and most preferably a total of six degrees of freedom, thereby enabling improved mobility of the substrate and / or the containment device.

[0141] In a further embodiment according to Figures 8a and 8b, both receiving devices 1, 2 are positioned next to each other, so that in this embodiment too, both substrates 3, 4 are loaded as shown in Figure 8a, with the gravitational influence on the first receiving device 1 and the second receiving device 2 being the same. For bonding, both receiving devices 1, 2 with the substrates are rotated 90° relative to each other so that they face symmetrically as shown in Figure 8b. The 90° rotational movement of the second receiving device 2 is carried out via the rotation axis BB, and the 90° rotational movement of the first receiving device 1 is carried out via the rotation axis B'-B'. After adjustment and approximation, the substrates 3, 4 are bonded together across the entire vertical plane. [Explanation of symbols]

[0142] 1 First accommodating device, first substrate holder 2 Second receiving device, second substrate holder 3 First board 4 Second board 5 Fixing element, first fixing means, second fixing means, fixing means 6 Loading pin opening 7 Further features of the containment device 8 Loading Pin 9,9' Area where stress pattern occurs when board is loaded 10 Swivel joint, swivel axis 11 Joining devices, joining equipment 12 First chamber section 13 Second chamber section 12u,13u surrounding wall 14 Ring seal 15 Moving device (driving means) 16 Distance change means, approach means 17 Board Stack AA rotation axis BB,B'-B' rotation axis

Claims

1. 1. A method for bonding substrates together, comprising: The method comprises, inter alia, the following steps in the following sequence: i) providing a first substrate (3) on a first substrate holder surface of a first substrate holder (1) and a second substrate (4) on a second substrate holder surface of a second substrate holder (2); ii) in a loaded state, fixing the first substrate (3) to the first substrate holder (1) and fixing the second substrate (4) to the second substrate holder (2); iii) positioning the second substrate holder (2) relative to the first substrate holder (1) so that in a bonding position the surfaces to be bonded of the first substrate (3) and the second substrate (4) face each other; iv) bonding said first substrate (3) to said second substrate (4); Equipped with In the loaded state, the first substrate holder surface and the second substrate holder surface are are positioned at the same angle relative to the Earth's gravitational force, In the loaded state, the first substrate holder surface and the second substrate holder surface are are oriented in the same direction relative to the Earth's gravitational force, When the first substrate (3) and the second substrate (4) are fixed, the same holding force is applied to the first substrate (3) and the second substrate (4), respectively. method.

2. In the loaded state, the first substrate (3) is placed on the first substrate holder surface and the second substrate (4) is placed on the second substrate holder surface. The method of claim 1.

3. The angle is a vertical angle.

3. A method according to at least one of claims 1 to 2.

4. When fixed in the loaded state, the same holding forces are provided in corresponding patterns on the first substrate (3) and the second substrate (4), so that the patterns of the holding forces are aligned at the joining position.

4. The method according to at least one of claims 1 to 3.

5. The fixing of the first substrate (3) and the fixing of the second substrate (4) are carried out simultaneously and within the same period of time.

5. The method according to at least one of claims 1 to 4.

6. The positioning includes rotating the second substrate holder (2) by 180°.

6. The method according to at least one of claims 1 to 5.

7. The positioning includes rotating the first substrate holder (1) and the second substrate holder (2) toward each other by 90°.

6. The method according to at least one of claims 1 to 5.

8. the same holding force is maintained during the joining; 8. The method according to at least one of claims 1 to 7.

9. An apparatus (11) for bonding substrates (3, 4) together, comprising: The device (11) comprises at least a) a first substrate holder (1) with a first substrate holder surface; a1) a first fixing means (5) for fixing a first substrate (3) to a first substrate holder surface; b) a second substrate holder (2) with a second substrate holder surface; b1) second fixing means (5) for fixing a second substrate (4) to the second substrate holder surface; c) positioning means (10, 15, 16) for positioning the second substrate holder (2) relative to the first substrate holder (1); and the apparatus (11) is movable into a loading state, in which the first substrate holder surface and the second substrate holder surface are disposed at the same angle relative to the gravitational force of the Earth; In the loaded state, the first substrate holder surface and the second substrate holder surface are are oriented in the same direction relative to the Earth's gravitational force, the first and second fastening means (5) are configured to provide the same holding force for fastening in the loaded state, Device (11).

10. the device (11) is configured such that, in the loaded state, the first substrate holder surface and the second substrate holder surface are arranged side by side and parallel and offset from each other; 10. The device (11) according to claim 9.

11. the second substrate holder is pivotable from the loading position to a bonding position; Device (11) according to at least one of claims 9 to 10.

12. The positioning means includes a swivel joint (10). Device (11) according to at least one of claims 9 to 11.

13. the first fixing means (5) and the second fixing means (5) are electrostatic fixing means (5); Device (11) according to at least one of claims 9 to 12.

14. in the bonding position, the first substrate holder (1) and the second substrate holder (2) form a bonding chamber, preferably a fluid-tight bonding chamber; Device (11) according to at least one of claims 9 to 13.

15. the first and second fastening means (5) are configured to provide the same holding force at least until they are moved into the joining position; Device (11) according to at least one of claims 9 to 14.

Images