Method for bonding a first substrate to a second substrate, device for bonding and assembly of a first and second substrate

Abstract

A method for bonding a first substrate (2u) to a second substrate (2o), wherein the first substrate (2u) has a primary section and the second substrate (2o) has a secondary section, wherein when bonding the first substrate (2u) to the second substrate (2o), a bonding wave (10) advancing along a bonding direction is formed between -- a first subsection in which the first substrate (2u) and the second substrate (2o) are joined, and -- a second subsection in which the first substrate (2u) and the second substrate (2o) are still to be joined, wherein preferably a subregion of the second substrate (2o) in the second subsection is offset in height relative to a subregion of the second substrate (2o) in the first subsection in a direction perpendicular to a main plane of extension (HSE), and wherein, in order to maintain a distance between the primary section and the secondary section, the second substrate (2o) is held during bonding in the second subsection in an end section remote from the bonding wave, particularly when the region of the second substrate (2o) is dropped between the end section and the bonding wave.

Description

[0001] Method for bonding a first substrate to a second substrate, device for bonding and arrangement of first and second substrate

[0002] The present invention relates to a method for bonding a first substrate to a second substrate, a device for bonding and an arrangement of first and second substrate.

[0003] In the semiconductor industry, substrates have been aligned and bonded together for several years. The connection, known as bonding, serves to create a multi-substrate stack. The substrates can be product substrates with functional units on both substrates to be bonded. A characteristic process in bonding, especially permanent bonding, preferably fusion bonding, is the most central, point-like contact possible between the two substrates.

[0004] One of the greatest challenges in bonding lies in the bonding process itself, from bond initiation to complete contact between the substrates' contact surfaces. Although the substrates can be aligned very precisely using alignment systems, distortions of the substrates can occur during the bonding process itself. The alignment of the two substrates can change significantly compared to their previous alignment, with deviations in the nanometer range now causing problems. Once the two substrate surfaces are bonded, separation is theoretically possible, but is associated with high costs, low throughput, and susceptibility to errors. In the semiconductor industry, all topics dealing with such problems are subsumed under the term "overlay."Overlay defects include the “run-out” defect, which is mainly caused by a distortion of at least one substrate during a bonding process.

[0005] The run-out error is particularly dependent on the position on the substrate along the substrate surface. It is particularly evident that the run-out error increases from the center to the periphery of the substrate. Such radially symmetric run-out errors occur primarily in fusion-bonded substrates that are contacted centrally by an actuator, such as a pin, and whose bond wave propagates independently, particularly radially, after contacting. In most cases, the error amplification at the edge increases linearly.

[0006] The run-out error depends on other factors. An important factor is the distance between the two substrates immediately before the start of the (pre)bonding process. To the extent that the upper, first substrate is deformed by deformation means, in particular, the distance between the substrates is a function of location. In particular, the distance between the substrates is greatest at the edge.

[0007] The run-out error also depends on temporal aspects, particularly the bond wave speed. In general, the error increases with increasing bond wave speed. A bond wave that propagates too quickly does not allow the substrate material sufficient time to optimally bond shortly after and / or on and / or before the bond wave. It can therefore also be crucial to control the bond wave in a time-dependent manner. In particular, the bond wave should be slowed down. Overlay and run-out errors can be understood as distortions in general.

[0008] Another problem is so-called edge defects (or edge voids). These micrometer- to millimeter-sized defects, which are usually gas inclusions, have been a known and disruptive problem in the semiconductor industry for years. The formation of edge defects also depends on the bonding wave speed, as existing gases are displaced radially symmetrically around the contact point during the bonding process. The gases can become trapped at the substrate edge.

[0009] The prior art contains several methods and systems with which attempts can be made to influence the bonding process, such as the documents US 11,031,369 B2, EP 3 005 407 B1 or US 10,763,243 B2. Influencing means in particular a targeted, active change and / or control of an initial state of at least one parameter. These parameters can be in particular gas composition, pressure, temperature and change in the shape of the substrates. In EP 3 005 407 B1, bonding is initiated after contacting the contact surfaces at the bond initiation point by dropping the upper substrate onto the lower substrate, whereby the substrates are deformed before and / or during bonding. The deformation can take place, for example, by mechanical adjusting means or by changing the temperature of the substrates by temperature control of the substrate holding devices.By selecting the gas or gas mixture and the pressure in the bonding chamber, the conditions for the bonding wave can be further influenced. The speed of the bonding wave can be controlled by the properties of the gas. In EP 3 005 407 B1, the bonding wave is slowed down by the presence of a gas.

[0010] In US 11,031,369 B2, for example, the pressure at the edge between the upper and lower substrates is changed, in particular reduced, using a vertical gas curtain around the periphery of the substrates to be bonded. In US 11,031,369 B2, the resulting vacuum at the edge pulls the substrates toward each other.

[0011] In US 10,763,243 B2, the lower substrate is convexly deformed by movable segments in the substrate receiving device. The lower substrate is fixed to the segments by vacuum.

[0012] The object of the present invention is to provide a device and a method for bonding two substrates, which increases the bonding accuracy, especially at the edges of the substrates. The invention thus relates to a method and a device for reducing or avoiding distortions and edge defects between two bonded substrates.

[0013] The present invention solves this problem with a method for bonding a first substrate to a second substrate according to claim 1 and with a bonding device according to claim 9, as well as with an arrangement according to claim 15. Advantageous developments of the invention are specified in the subclaims. The scope of the invention also includes all combinations of at least two features specified in the description, the claims, and / or the drawings. For specified value ranges, values ​​within the specified limits are also considered to be disclosed as limit values ​​and can be claimed in any combination.

[0014] According to a first aspect of the present invention, a method is provided for bonding a first substrate, also referred to as lower substrate, to a second substrate, also referred to as upper substrate, wherein the first substrate has a primary section and the second substrate has a secondary section, wherein during bonding of the first substrate to the second substrate, a bonding wave advancing along a bonding direction is formed between

[0015] -- a first section in which the first substrate and the second substrate are connected, and

[0016] -- a second subsection in which the first substrate and the second substrate are still to be connected is formed, wherein preferably a subregion of the second substrate in the second subsection is offset in height relative to a subregion of the second substrate in the first subsection in a direction running perpendicular to a main extension plane, wherein in order to maintain a distance between the primary section and the secondary section, the second substrate in the second subsection is held in an end section facing away from the bonding wave, preferably in a locally limited manner, during bonding, in particular when the region of the second substrate between the end section and the bonding wave is dropped.

[0017] In contrast to the methods known from the prior art, the invention provides that the end section of the second substrate is held during bonding. This advantageously actively influences the distance between the primary section and the secondary section, i.e. the distance between the regions of the first substrate and the second substrate that lie opposite one another and have not yet been bonded while lying in the second subsection. In particular, the primary section and the secondary section are the regions of the first and second substrate to be bonded last. It is precisely by holding the end section of the second substrate that any falling of the end section due to gravity is counteracted. In other words: by holding the end section, the distance between the primary section and the secondary section is maintained.It has been found that by holding the end section of the second substrate, a controlled deposit of the secondary section is possible, whereas dropping the end sections as known from the prior art occurs in an uncontrolled manner. The controlled holding has a particularly advantageous effect on the precision of the floor between the first substrate and the second substrate. In particular, the targeted holding at the end section represents a departure from the dropping of the second substrate as known from the prior art. It has proven particularly advantageous that the end section is held for a large part, in particular for a comparatively long period of time, during the bonding, i.e., a bonding process. In particular, it is provided that the holding of the end section continues in particular even when the area of ​​the second substrate between the bonding wave and the end section has already been dropped, i.e.a corresponding fixation is at least partially released. Furthermore, the second substrate is preferably held locally in the end region. This differs in particular from measures in which an effect on the second substrate is exerted globally in the second subsection, for example, by a gas cushion or a gas curtain, or by coordinated or controlled deformation systems.

[0018] While the first substrate rests, for example, on a first substrate receiving device, and generally does not undergo any gravitational movement, in particular a falling movement, the second substrate is preferably attached to an underside of a substrate receiving device or an upper substrate receiving device. During bonding, a fixation in the area between the bonding wave and the end section on the substrate receiving device for the second substrate must be released, causing the areas that have not yet been bonded to fall, at least under the influence of gravity. Holding the end section counteracts this. Therefore, the second substrate is preferably arranged above the first substrate.

[0019] However, in the prior art, the gap at the edge between the substrates to be bonded, in particular between the primary section and the secondary section, while maintaining the fixation of the upper substrate at the outer edge during the propagation of the bonding wave is not actively and controlled reduced or adjusted. However, distortions are particularly dependent on the distance between the two substrates and the speed of the bonding wave. The distance between the substrates is greatest at the edge when contact is made centrally. The speed of the bonding wave is also greatest at the edge. If the substrates fall onto one another too quickly, the bonding wave speed is very high. This is particularly the case at the edge when the bonding wave propagates from the center to the edge. At the beginning of the bonding process, for example after central contact has been made, the upper or second substrate is fixed at the circumference to the upper substrate holding device.The upper substrate's fixation is then released, allowing the bonding wave to advance freely. If the upper substrate's fixation is not released or only partially released, the bonding force will eventually prevail over the vacuum fixation force as the bonding wave propagates and the bonding force increases. The fixation to the upper substrate holder breaks due to a leak, and the upper substrate falls and bonds completely to the lower substrate. The distance between the lower and upper substrates, as well as the propagation of the bonding wave, can then no longer be controlled.

[0020] If the distance between the upper and lower substrates is too large or the fixing force is too strong, the fixing to the upper substrate holding device may be maintained, but the bonding wave would be stopped.

[0021] The term "end section" refers, in particular, to that section of the second substrate which, starting from a first contact point between the first substrate and the second substrate, is located in the last third, preferably the last quarter, and particularly preferably the last fifth of the second substrate yet to be bonded, i.e., the secondary section, as seen in the bonding direction. This refers, in particular, to the last section of the second substrate still to be bonded. In particular, the end section comprises the edge of the second substrate.

[0022] According to a preferred embodiment, by holding the end section, the bonding speed at which the bonding wave moves along the bonding direction during bonding is controlled. In particular, the bonding speed is reduced, i.e., the progression of the bonding wave is decelerated or slowed down. This has a beneficial effect on the accuracy of positioning the sections still to be bonded.

[0023] The invention is also based on the idea that during bonding, in particular during the propagation of a bonding wave, preferably during fusion bonding, this bonding wave is influenced. Influencing refers in particular to a targeted, active change and / or control of an initial state of at least one parameter.

[0024] In a first embodiment, the targeted influencing of the bonding wave is achieved through an effective, flexible, and stronger fixation of the upper substrate at the outermost edge. The upper substrate can be held longer at the outermost edge of the substrate holding device, for example, by a sealing system, preferably with at least two flexible sealing lips or sealing rings. This advantageously enables efficient influencing of the bonding wave, since the upper or second substrate, once the bonding wave has built up sufficient stress on the vacuum fixation, does not fall uncontrollably at the edge due to a leak at the fixation.

[0025] In a second preferred embodiment, it is provided that the targeted influencing of the bonding wave is additionally carried out by a regulated and / or controlled change in the distance at the substrate edge by means of a deformation system and / or sub-segment during bonding, wherein the upper substrate can be held effectively and for a longer period at the outermost edge of the substrate receiving device by the sealing system, in particular with at least two flexible sealing lips or sealing rings.

[0026] This advantageously allows a particularly efficient influence on the bond wave.

[0027] In particular, it is intended that the deformation system be modified during bonding, for example, by means of a control device. This can be achieved, for example, preferably by means of movable components or sub-segments that can be displaced, for example, along a vertical direction running perpendicular to the main extension plane. In this case, the control device can arrange the corresponding components at different heights using appropriate controls.

[0028] In a further preferred embodiment, it is provided that the end section is held at least for a period of time in which the bonding is at least 70%, preferably at least 80%, and particularly preferably at least 90% or even at least 98% complete, and / or wherein the end section is held while the area between the bonding wave and the end section is made available for bonding, at least under the effect of gravity. In other words, the end section is held for as long as possible during the bonding process. This ensures, in particular, that no distortions or defects occur at the edge of the substrate stack. Such distortions or defects would otherwise occur if the end section was dropped prematurely, as is common in the prior art.To ensure precise, centric, point-like contact, an upper substrate holder, designed with a centric hole and an actuator—for example, a pin that can be moved translationally within the centric hole—is provided with a radially symmetrical fixation. This is where the initial contact occurs, which determines the starting point of the bonding process.

[0029] Furthermore, it is conceivable that a vacuum is still generated in the vacuum segment associated with the end section even if the fixation of the second substrate has already been released in other areas, for example, by means of other vacuum paths or vacuum channels. For example, it is provided that in the substrate receiving device for the second substrate, the fixation is released during bonding in an area between the first subsection and the end section held by the vacuum segment, while the end section is still held.

[0030] Preferably, it is provided that, to hold the end section, a vacuum is generated in a vacuum segment extending perpendicular to the bonding direction, which preferably extends circumferentially and is particularly preferably self-contained, in particular delimited by a sealing system. For this purpose, for example, a vacuum system is provided which provides the vacuum segment between a substrate receiving device for the second substrate and the end section. In particular, it is provided that the vacuum segment is limited to the end section or at least can be controlled separately. In other words: the vacuum provided for holding the end section acts, preferably exclusively, on the end section of the second substrate or can at least work more strongly and / or independently of other vacuum channels with which other sections of the second substrate are held.This can be achieved, for example, by not providing a sealing system for the other vacuum tracks, with which the vacuum can act specifically on a more spatially limited area. This advantageously makes it possible for the vacuum to be specifically formed locally at the end section and to hold it. In particular, an increased holding force is caused which counteracts a gravitational effect or a bonding force. In particular, it is provided that the substrate receiving device for the second substrate has a sealing system with which the end section can be held only in an area assigned to the end section. In the other areas assigned to the sections outside the end section, preferably no sealing system and thus no vacuum segment is formed, even if vacuum tracks run or open into these areas.In other words, the areas outside the end section are preferably free of any sealing system. This ensures, with comparatively simple means, that the end section is held more firmly than the other sections.

[0031] The vacuum segment is in particular at least partially delimited or surrounded or formed by a sealing system. In other words: the vacuum segment is preferably characterized in that it has a sealing system. The sealing system comprises at least one, preferably at least two sealing elements which delimit or delimit the vacuum segment. It is particularly preferred if the vacuum segment extends over a strip-shaped, in particular annular, region. The vacuum segment is preferably formed between a substrate receiving device for the second substrate and the second substrate, in particular in the region of the end section, and is delimited laterally by the sealing system. The vacuum segment is preferably concentric to a first contact point at which the bonding process begins and extends in particular in the shape of a ring or ring segment.

[0032] In particular, it is provided that during bonding, a sub-segment, in particular of a substrate receiving device for the second substrate, which is assigned to the end section of the second substrate, is displaced in certain areas, wherein in particular a distance between the primary section and the secondary section is set in a targeted or controlled manner. This allows additional influence to be exerted on the distance between the primary section and the secondary section. By actively reducing the height of the exit gap, which is formed by the distance between the primary section and the secondary section in the second sub-section, and at the same time by more firmly fixing the upper substrate, the air exit speed between the substrates to be bonded can be controlled for a longer period of time and thus the bonding wave can be influenced.In a preferred embodiment of the method, the controlled reduction of the distance between the substrates at the edge is carried out by deforming the upper substrate in the edge region by means of displaceable components, in particular displaceable, annular sub-segments.

[0033] In a further embodiment of the method, the controlled reduction of the distance between the substrates at the edge is carried out by deforming the upper substrate in the edge region by means of displaceable components, in particular displaceable, separately controllable, ring-segment-shaped sub-segments.

[0034] In a further preferred embodiment, the second, upper substrate is held in the end section during bonding with a force that is greater than the forces acting on other regions of the second segment. In particular, the gravitational force and a force acting on the first substrate and the second substrate during bonding are overcompensated by this holding. This counteracts, in particular, forces that would otherwise pull the second substrate, in particular the end section, downward or separate it from the substrate receiving device.

[0035] In particular, it is provided that, in addition to holding the end section for the relative alignment of the primary section and the secondary section to one another, in particular with respect to a direction running substantially parallel to the bonding direction, a first curvature of the first substrate and / or a second curvature of the second substrate is modified by means of a deformation system in a region adjacent to the bonding wave and / or in a region encompassing the bonding wave. Preferably, during bonding by means of the deformation system, a difference between the first curvature and the second curvature along the bonding direction is kept substantially constant, at least in sections. The upper and lower substrates can be deformed, for example convexly deformed, by means of deformation means. This supports central contacting and the avoidance of air inclusions.

[0036] In particular, it is provided that the first curvature and / or the second curvature in the region adjacent to the bonding wave or in the region encompassing the bonding wave is specifically modified locally, in particular immediately before the region adjacent to the bonding wave is bonded. In particular, it is provided that the modification of the first curvature and / or the second curvature results in a corresponding adjustment that ensures that, after the bonding process, the primary section and the secondary section are arranged one above the other, preferably congruent with one another, in a direction perpendicular to the main extension plane. In other words, the overlay is optimized.In this way, it is advantageously possible to increase positioning accuracy, ensuring that the primary section and secondary section of the first and second substrates are not offset from one another in a direction parallel to the bonding direction. This proves particularly advantageous if structures and / or functional units are formed in the primary section and secondary section, which are intended to connect to one another, in particular electrically, in the bonded state. These structures and / or functional units include, for example, vias and / or connections of electrical or electronic components, such as MEMS or LEDs.

[0037] Preferably, the difference between the first and second curvatures is deliberately kept constant over a distance that amounts to more than 50%, preferably more than 75%, and particularly preferably more than 80% of a bonding distance, where the bonding distance refers to the entire length over which the bonding process takes place. It has been found that by appropriately adapting the first and second curvatures to one another, the distortion or the extent of the distortion between the first and second substrates can be kept as low as possible. This has a positive effect on any tension between the first and second substrates, as well as on the positioning accuracy when aligning the first and second substrates to one another.In this case, "essentially constant" means that the first curvature and / or the second curvature deviates by no more than 15%, preferably no more than 10%, and particularly preferably no more than 5% from twice the arithmetic mean of the first curvature and the second curvature. Furthermore, it is preferably provided that the various deformation means in the individual deformation sections along the bonding path specifically ensure that the first curvature and the second curvature are essentially constant in their sum. The influence of the individual deformation means can differ from one another. In particular, the deformation means are individualized with regard to their influence or effect for the respective region to be bonded, which is assigned to the individual deformation means. In a preferred embodiment, a method for bonding, in particular fusion bonding, a first or lower substrate to a second or lower substrate is disclosed.upper substrate is provided in a bonding chamber, which has the following steps: a) fixing the substrates, b) aligning the substrates, c) bringing the substrates closer together, d) contacting the substrates at a bond initiation point or at a first contact point, e) bringing the substrates closer together to generate a radially symmetrical bonding wave that runs from the bond initiation point to the edge of the substrates, wherein the radially symmetrical fixing of the upper substrate at the outermost edge in the region of the sealing lips is maintained despite increasing bonding force, and / or f) controlled reduction of the distance between the substrates at the edge by deforming the upper substrate in the edge region to reduce the bond wave speed, and / or g) switching off the fixing in the region of the sealing lips of the upper substrate receiving device. The release of the vacuum can be controlled in particular by the movement of the displaceable segments.With a movable segment acting on the outer substrate section, the fixation can be released as the bonding wave advances in the last outer segment and / or after the bonding wave has passed through. In a preferred embodiment, the fixation of the upper substrate holding device in particular can be maintained after contact has been made between the centers of both substrates. The additional sealing lips prevent the second, upper substrate from spontaneously detaching from the vacuum fixation. At the same time, the edge region of the upper substrate is brought closer to the edge region of the lower substrate by lowering the movable, circular or ring-segment-shaped outer components of the upper substrate holding device. Accordingly, the bonding wave or its propagation can be varied by influencing the edge distance between the substrates.Thus, distance control combined with improved and flexible fixation of the upper substrate in the edge region allows for reproducible control of the bond wave. In a preferred embodiment of the method, the lower substrate is fixed over its entire surface and not curved.

[0038] In a further embodiment, the controlled reduction of the distance between the substrates at the edge is achieved by switching the outer zone(s), particularly in the vacuum segment, from vacuum to pressure. This pushes the outermost edge of the upper substrate toward the lower substrate, reducing the air exit velocity between the substrates.

[0039] Preferably, several vacuum tracks are combined to form vacuum track arrangements that can be individually controlled, i.e., evacuated or flooded separately. While the inner vacuum track arrangements are evacuated, the outermost vacuum track segment or the vacuum track arrangements assigned to the vacuum segment are flooded with overpressure. In a further embodiment, several sealing lips define different (edge) regions that enable more flexible fixation of the upper substrate, wherein the outermost region between the two outer sealing lips effects the controlled reduction of the distance between the substrates at the edge by switching from vacuum to pressure, in that the edge of the upper substrate is pressed with overpressure from the rear towards the lower substrate.

[0040] A further subject of the present invention is a device for bonding a first substrate to a second substrate, in particular by means of a method according to the invention, wherein the first substrate has a primary section and the second substrate has a secondary section, wherein the device is configured such that during bonding of the first substrate to the second substrate, a bonding wave advancing along a bonding direction between

[0041] -- a first section in which the first substrate and the second substrate are connected, and

[0042] -- a second subsection is formed in which the first substrate and the second substrate are still to be bonded, wherein preferably a subregion of the second substrate in the second subsection is vertically offset from a subregion of the second substrate in the first subsection in a direction perpendicular to a main extension plane, wherein the device is configured such that, in order to maintain a distance between the primary section and the secondary section, the second substrate in the second subsection is held in an end section facing away from the bonding wave. All properties and advantages described for the method apply analogously to the device and vice versa.

[0043] In a further embodiment of the present invention, at least one sealing system is provided on the device to hold the end section, the sealing system being designed such that, during bonding, a vacuum segment is formed in an area enclosed by the sealing system, a vacuum opening for generating a vacuum in the vacuum segment being arranged in the area enclosed by the sealing system. In particular, the vacuum segment is characterized in that it is formed in a locally limited manner, preferably by the sealing system, between the upper substrate receiving device and the second substrate, preferably its end section. In this case, the sealing system limits the vacuum segment in a direction that runs parallel to the bonding direction.

[0044] Furthermore, it is preferably provided that the sealing system is integrated into a substrate receiving device for holding the second substrate and / or the vacuum opening is embedded in the substrate receiving device.

[0045] Preferably, the sealing system, in particular a first sealing element and / or a second sealing element, is integrated in the substrate receiving device in a retractable or countersunk manner. By countersinking the sealing system, in particular the sealing elements, in particular sealing lips, that delimit the vacuum segment, it is advantageously ensured that the second substrate is held in the substrate receiving device with as much surface area as possible. By means of at least two flexible sealing lips on the outer circular section with separately controllable vacuum fixation in the area between the sealing lips, the fixation of the upper substrate to the upper substrate receiving device can be maintained for longer as the bonding wave propagates. The flexible sealing lips are countersunk with respect to the holding surface and prevent leakage at the fixation at the outermost edge, counteracting the strong tensile force acting by the bonding wave.If the sealing lips are located on a movable sub-segment in the outer circular segment of the upper substrate receiving device, the gap between the primary section and the secondary section at the substrate edge is additionally actively changed.

[0046] To ensure precise, centric, point-like contact, an upper substrate receiving device or substrate holder, equipped with a centric bore and a pin that can be moved translationally within it, is provided with a radially symmetrical fixation. Another conceivable option would be to use a nozzle as an actuator that uses a fluid, preferably a gas, to apply pressure instead of the pin. The substrates are brought closer together in a controlled manner until they reach a defined distance. The actuator in the centric bore of the upper substrate receiving device serves to controllably deflect the fixed, upper substrate. The substrates are brought closer together through a translational movement, resulting in centric, point-like contact.

[0047] The upper substrate receiving device has fixing elements for fixing the upper substrate, wherein the fixing elements can be grouped into zones, wherein the zones are preferably arranged in a ring shape, more preferably in a circular ring shape or radially symmetrically. The fixing elements or fixings can be controlled in particular independently of the vacuum segment. In a first embodiment, the ring-shaped arrangement enables the upper substrate to be fixed exclusively to an outer circular ring-shaped zone, wherein the inner region of the holding surface of the substrate receiving device contains the central bore for an actuator. In a further embodiment, the fixing consists of several circular ring-shaped zones, in particular two to three circular ring-shaped zones. In a further embodiment, the fixing consists of several ring-segment-shaped zones.Radially symmetric fixation, for example, involves attached vacuum holes or comparable vacuum elements with which the upper substrate can be fixed.

[0048] Preferably, all fixing elements of the same zone can be controlled by a single control element, in particular a control valve when using vacuum fixing elements. This advantageously makes it possible to switch all fixing elements of a zone simultaneously. Particular reference is made to WO 2022 / 002345 A1. The lower substrate can, in particular, be fixed over its entire surface on the holding surface of the lower substrate receiving device. The fixation preferably involves either attached vacuum holes or comparable vacuum elements, with the aid of which the lower substrate can be fixed.

[0049] After the centers of both substrates have been contacted, the fixation of the upper substrate holding device is released in the prior art, in particular in a controlled and step-by-step manner. In particular, reference is made to the documents WO 2017 / 140348 A1 and EP 3 886 149 A1. For example, in WO 2017 / 140348 A1, the upper substrate falls downwards partly due to gravity and partly due to a bonding force acting along the bonding wave and between the substrates. The upper substrate is connected radially to the lower substrate from the center to the side edge. This results in the formation of a radially symmetrical bonding wave, which runs particularly from the center to the side edge. During the bonding process, the two substrates push the gas present between the substrates ahead of the bonding wave. After the fixation of the upper substrate has been released, the upper substrate rests on a type of gas cushion during the fall.

[0050] Initially, after central contacting, the upper substrate is fixed around the periphery to the upper substrate holding device. In the prior art, the fixation of the upper substrate is then released, allowing the bonding wave to advance freely. However, if the substrates fall onto one another too quickly, the bonding wave speed is very high. This is particularly the case at the edge, as the bonding wave propagates from the center to the edge. If the distance between the upper and lower substrates is too large or the fixing force is too strong, the fixation of the upper substrate to the upper substrate holding device may be maintained, but the bonding wave would be stopped.

[0051] The fixing force at the edge of the upper substrate and the forces acting after contacting in the center of the substrates and due to the advancing bonding wave between the substrates compete until the bonding force predominates and the upper substrate detaches from the upper substrate holding device. From this point on, the upper substrate no longer has contact with the upper substrate holding device and the bonding wave speed can no longer be controlled. The distance between the lower and upper substrates, as well as the propagation of the bonding wave, can then no longer be controlled. The invention can be seen in particular as a further development of the prior art procedure. After contacting the centers of both substrates, the fixing of the upper substrate is maintained in a controlled manner exclusively at the edge of the upper substrate holding device by means of the sealing lips.

[0052] In order to hold the upper substrate to the upper substrate holding device for longer and thereby influence the bond wave speed, elastic and / or flexible sealing lips are used on the edge or on the outer circular segment of the holding surface of the upper substrate holding device. The sealing lips can be partially recessed into the holding surface of the substrate holding device. Thanks to the additional sealing lips, the upper substrate is in contact with the upper substrate holding device for longer at the edge, and the gap between the upper and lower substrates is actively influenced. The flexible sealing lips or sealing rings or sealing bodies or sealing strips can be attached to movable sub-segments on the edge of the substrate holding device, further reducing the distance between the substrates at the edge.This can, among other things, reduce the tension between the center of the substrate and the edge of the substrate, so that the upper substrate can be held in place for longer. The controlled approach of the ring-shaped or ring-segment-shaped edge segment of the edge-fixed upper substrate when bonding the first or lower substrate to the second or upper substrate reduces the air outlet gap at the edge of the substrates and thus changes the air outlet speed, in particular reduces it, which leads to a reduction in distortions and edge defects. Design features of the upper substrate holding device can actively influence the gap between the substrates to be bonded, in particular the gap at the edge of the substrates, by changing the distance at the upper substrate edge and by preventing the upper substrate from detaching too early.A relative approach of both substrates as well as an approach of the circular outer edge segment of the upper substrate towards the lower substrate can be combined to control the gap height at the edge of the substrates.

[0053] After the bond is initiated at the bond initiation point, the upper substrate is additionally secured by at least two flexible sealing lips at the edge of the substrate receiving device. In a first embodiment, there are two circular, flexible sealing lips at the edge of the upper substrate receiving device. Flexible sealing lips at the outermost edge of the upper substrate receiving device allow the vacuum between the upper substrate and the support surface of the upper substrate receiving device to last longer, thereby influencing the bond wave. Between each of the sealing lips, there is a vacuum supply bore or vacuum opening into which a vacuum channel opens.

[0054] In a second embodiment, there are at least two ring-segment-shaped, flexible sealing lips on the edge of the upper substrate receiving device. Preferably, there are between 2 and 12, more preferably between 4 and 10, and most preferably between 4 and 8 ring-segment-shaped, flexible sealing lips on the edge of the upper substrate receiving device. These sealing lips can also be sealing rings or sealing bodies, depending on the shape of the substrate receiving device.

[0055] In a preferred embodiment, the vacuum track for the vacuum supply for the area between (each) two sealing lips or for the area inside a ring-segment-shaped sealing lip can be individually controlled, i.e. it can be evacuated or flooded separately. This makes it possible to construct individually controllable vacuum tracks or vacuum arrangements, each for fixing the upper substrate in the area of ​​the sealing lips in the outermost area of ​​the upper substrate holding device and for fixing the upper substrate in the circular and / or annular area or outside the sealing lips. The at least two sealing lips are preferably set back with respect to the holding surface of the substrate holding device, so that only a part of the sealing lip is located outside the holding surface. Advantageously, the sealing lip can be guided in a groove and (partially) countersunk into the upper substrate holding device.The recess allows for easy fixation and, at the same time, good lateral expansion of the elastic sealing lips or sealing rings. The exact design depends, among other things, on the selected shape and material of the individual sealing lips or sealing rings.

[0056] The sealing lips or sealing bodies are designed so that, when the upper substrate is fully suctioned onto the substrate at the start of the process, no stress is exerted on the substrate. This is achieved, in particular, by the recessed sealing lips or sealing rings relative to the holding surface of the substrate holding device. If, during bonding, the upper substrate detaches from the upper substrate holding device due to the pressure of the bonding wave, the sealing lips or sealing rings ensure that the vacuum is maintained in the area between two sealing lips or sealing rings, thus keeping the upper substrate in place.

[0057] The vacuum value of the separately evacuatable and controllable vacuum supply and the distance between the sealing lips or sealing rings influence the holding force in the area of ​​the sealing lips or sealing rings, which counteract the bonding force or the bonding wave.

[0058] The vacuum is maintained between the flexible and / or elastic and / or pliable sealing lips or sealing rings and the upper substrate, so that the upper substrate remains fixed to the outermost edge of the upper substrate holder despite detachment in other areas of the substrate holding surface. The upper substrate is thus still fixed to the outermost edge during the bonding process and does not lose contact with the upper substrate holder.

[0059] The area at the edge of the outer substrate holding surface in which the sealing elements, in particular the sealing lips or sealing rings, are located is in particular 2 cm from the outer edge of the upper substrate. In a preferred embodiment, the upper substrate receiving device contains at least one circular and / or annular and / or ring-segment-shaped, movable sub-segment on which the flexible sealing lips or sealing rings are located, so that the outermost edge of the upper substrate can also be moved toward the lower substrate. By reducing the distance at the edge, the air outlet speed between the substrates is reduced and thus also the bond wave speed.

[0060] The separately controllable vacuum track or the vacuum segment(s) for the area between two sealing lips or sealing rings are integrated into the movable segments of the upper substrate support device. The movable segments, including the vacuum tracks or vacuum segments, are preferably designed in a circular shape. It is also conceivable to provide additional movable sub-segments and / or non-movable sub-segments that are free of sealing systems. These are not suitable for forming a vacuum segment.

[0061] What all embodiments have in common is that the elastic and / or flexible sealing lip can be compressed or stretched without losing contact with the substrate. The upper substrate is convexly curved in the center and contacts the lower substrate. The upper substrate remains fixed at the edge to the upper substrate holding device by means of vacuum fixation. The sealing lips or sealing rings can maintain the fixation at the edge for longer, particularly in the area between two sealing lips or sealing rings, and there is no premature vacuum interruption at the edge, which would lead to the complete fall of the upper substrate. The complete fall of the upper substrate means that the bonding wave can no longer be controlled or slowed down.

[0062] The sealing material is advantageously made of plastic and is elastic and / or flexible. The sealing lip consists, for example, of the following materials or material mixtures: thermoplastic elastomers, in particular thermoplastic polyurethane (TPU), polytetrafluoroethylene (PTFE), silicone, fluoroelastomers (FKM), polyetheretherketone (PEEK), acrylonitrile butadiene rubber (NBR), etc. In a preferred embodiment, the upper substrate receiving device, in addition to the at least two sealing lips or sealing rings in the outer ring region, has a deformation system for bringing the edge zone of the upper substrate closer to the edge zone of the lower substrate. Preferably, the deformation system has at least one deformation means arranged along the bonding direction. In particular, the deformation system is changed during bonding, for example by means of a control device.This can be achieved, for example, preferably by at least one movable outer segment that can be displaced along a vertical direction perpendicular to the main extension plane. In this case, the control device can arrange the corresponding segments at different heights using appropriate controls.

[0063] The upper substrate receiving device thus has a dynamic, modifiable substrate receiving device surface at the edge with which the edge of the upper substrate, in particular the outermost circular section of the upper substrate, can be moved towards the lower substrate. This reduces the distance between the two substrates at the edge and thus actively reduces the exit gap at the edge without losing the fixation of the upper substrate at the outermost edge, since the sealing lips or sealing rings ensure the fixation at the edge. In a preferred embodiment, the substrate receiving device is constructed from a movable segment at the edge and a non-movable segment in the inner region. In a second embodiment, the substrate receiving device is constructed from two movable segments at the edge and one non-movable segment in the inner region.In a third embodiment, the substrate receiving device is constructed from at least two movable, ring-segment-shaped segments at the edge and one non-movable segment in the inner region.

[0064] The movable segments are controlled or regulated before and / or during the passage of the bonding wave in such a way that a lowering of the components creates a new, particularly geometrically altered, state for the bonding wave or the area adjacent to the bonding wave. In particular, the distance at the edge of the substrates is reduced.

[0065] In a first embodiment, a displaceable circular ring segment is present in the outer ring section. The displaceable outer ring section has a width between 0.5 cm and 5 cm, preferably between 1 cm and 4 cm, more preferably between 1.5 cm and 3 cm. In particular, the displaceable outer ring section has a width of 2 cm.

[0066] In a second embodiment, two movable circular ring segments are provided in the outer ring section. For example, it is conceivable that, in the case of two movable segments, the set height of the individual deformation sections is different. In particular, it is provided that the movable deformation sections only move during the bonding process, rather than already being displaced as soon as the bonding process begins.

[0067] In a third embodiment, at least two, preferably between 4 and 12, more preferably between 4 and 8 displaceable ring-segment-shaped segments are present in the outer ring section.

[0068] The movable contact surface is preferably formed by a segment into which several fixing elements are integrated. Vacuum fixing is the preferred type of fixing. Vacuum fixing preferably consists of several vacuum tracks that emerge at the surface of the substrate receiving device. The vacuum tracks are preferably individually controllable. In a preferred embodiment, several vacuum tracks are combined to form vacuum track arrangements that are individually controllable, i.e., can be evacuated or flooded separately. The vacuum tracks or vacuum channels are integrated into the movable sub-segments as well as the non-movable segments of the upper substrate receiving device.

[0069] The movable sub-segments can be adjusted in height as a whole within the substrate receiving device. Preferably, corresponding sub-segments are circular in shape and arranged concentrically to one another. Integrated on and / or into this movable contact surface are at least two sealing lips or sealing rings, which enable the upper substrate to be held in place for a longer period at the outermost edge of the upper substrate receiving device, even if the other fixing elements or fixing segments have already been released or loosened by the pressure of the advancing bonding wave. If several movable circular-ring segments are present, the sealing lips or sealing rings are preferably located in the outermost of the movable segments, so that the upper substrate remains held in place at the edge by the sealing lips or sealing rings.

[0070] The bonding process can be started by centrally contacting the upper and lower substrates. The upper substrate is not released immediately or completely from the fixation at the edge of the upper substrate holding device. The sealing lips on the upper, outer substrate edge enable better vacuum fixation of the upper substrate in the edge area. This is because the sealing lips, in addition to the fixation elements, increase the suction pressure of the vacuum fixation through better sealing and can therefore counteract the tensile force exerted by the bonding wave. The vacuum, and thus the effective fixation force, can be preferably adjusted in a controlled manner and can be maintained for longer. The area between two sealing lips or between each two sealing lips has a separately evacuated and controllable vacuum supply.

[0071] Distortions depend particularly on the distance between the two substrates immediately before the start of the bonding process and / or during the bonding process. If the upper substrate is deformed by deformation means, especially convexly deformed in the center, the distance between the substrates is a function of location. The minimum distance is located in the area of ​​the convex maximum of the deformed upper substrate. The maximum distance, at least before the start of the bonding process, is located in the area between the substrates at the edge.

[0072] During the bonding process, the height of the individual movable sub-segments is controlled and adjusted, which allows the curvature in the outer area adjacent to the bonding wave to be influenced accordingly.

[0073] By lowering the movable (circular ring) sub-segments at the edge of the upper substrate holding device, the distance between the substrates at the edge is deliberately reduced, thus reducing distortions, especially at the edge. The sealing lips allow for an optimal balance between sufficient fixation of the upper substrate and advancement of the bonding wave. In particular, the distance between the substrates below the convex maximum immediately before bonding is set to less than 500 pm, preferably less than 100 pm, even more preferably less than 50 pm, most preferably less than 20 pm, and most preferably less than 10 pm.

[0074] In particular, the distance between the substrates below the convex maximum immediately before bonding is set between 0.01 pm and 20 pm.

[0075] The distance between the substrates at the edge is set immediately before bonding in particular to be less than 5 mm, preferably less than 2 mm, even more preferably less than 1 mm, most preferably less than 0.5 mm, most preferably less than 0.1 mm.

[0076] The distance between the substrates at the edge can be set during bonding in particular to less than 0.1 mm, preferably less than 50 pm, more preferably less than 10 pm, most preferably less than 1 pm, most preferably less than 0.5 pm.

[0077] By means of movable, circular-ring-shaped components or segments at the edge or outer circular segment of the upper substrate support device, which can be moved along a vertical direction perpendicular to the main extension plane, the distance between the substrates at the edge is reduced immediately before and / or during bonding. In particular, the distance between the substrates at the edge can be continuously reduced after contacting.

[0078] The device preferably comprises a first, lower and / or a second, upper substrate receiving device. The substrate receiving devices, which are preferably used for the embodiments according to the invention, have fixing devices. The fixing devices serve to hold the substrates with a fixing force or with a corresponding fixing pressure.

[0079] The fixations may include, in particular, the following: - Mechanical fixations, in particular clamps, or

[0080] - Vacuum fixations, especially with

[0081] - individually controllable vacuum tracks or

[0082] - interconnected vacuum tracks, or

[0083] - Electrical fixations, in particular electrostatic fixations, or

[0084] - Magnetic fixings or

[0085] - Adhesive fixations.

[0086] The fixations are, in particular, electronically controllable. Vacuum fixation is the preferred fixation type. Vacuum fixation preferably consists of several vacuum tracks that emerge at the surface of the substrate receiving device. The vacuum tracks are preferably individually controllable. In a preferred embodiment, several vacuum tracks are combined to form vacuum track segments that are individually controllable, i.e., can be evacuated or flooded separately. Each vacuum segment is preferably independent of the other vacuum segments. This makes it possible to construct individually controllable vacuum segments. The vacuum segments are preferably ring-shaped and / or circular and / or ring-segment-shaped. Substrate receiving devices with controllable vacuum segments have been disclosed, for example, in WO 2022 / 002345 A1. Reference is made to this document in this regard.

[0087] If the fixing elements are designed as vacuum fixing elements, the pressure in the vacuum fixing elements is between 0.01 mbar and 1000 mbar, preferably between 0.01 mbar and 800 mbar, even more preferably between 0.01 mbar and 500 mbar, most preferably between 0.01 mbar and 100 mbar, and most preferably between 0.01 mbar and 10 mbar. The differential pressure between the higher, external pressure and the lower, internal pressure in the vacuum fixing elements is the contact pressure on the substrate, which leads to the fixing of the substrate.

[0088] By having at least two flexible sealing lips on the outermost edge of the upper substrate holding device, the vacuum between the upper substrate and the support surface of the upper substrate holding device can last longer, which can influence the bonding wave. A vacuum supply hole is located between each two sealing lips. In a preferred embodiment, the vacuum track for the vacuum supply for the area between (each) two sealing lips can be individually controlled, i.e. it can be evacuated or flooded separately. This makes it possible to construct individually controllable vacuum tracks or vacuum segments, each for fixing the upper substrate in the area of ​​the sealing lips in the outermost area of ​​the upper substrate holding device and for fixing the upper substrate in the inner circular area behind or outside the sealing lips.

[0089] The at least two sealing lips are preferably recessed relative to the holding surface of the substrate receiving device, so that only a portion of the sealing lip is located outside the holding surface. Advantageously, the sealing lip can be guided in a groove and (partially) recessed into the upper substrate receiving device. This recess allows for easy fixation and, at the same time, good lateral expansion of the elastic sealing lips. The exact design depends, among other things, on the selection of the shape and material of the individual sealing lips.

[0090] To ensure precise, centric, point-like contact, an upper substrate support device with a radially symmetrical fixation is used. It is equipped with a centric bore and a deformation element or actuator. A pin that can be moved translationally within the centric bore or a nozzle that uses a fluid, preferably a gas, to apply pressure instead of the pin would be conceivable.

[0091] The force with which the deformation element acts on a substrate is between 0.1 N and 1000 N, preferably between 0.1 N and 500 N, more preferably between 0.1 N and 250 N, most preferably between 0.1 N and 200 N, most preferably between 0.1 N and 100 N.

[0092] The substrate holding device contains sensors for monitoring relevant process parameters. Sensors for monitoring the distance between the substrate and the substrate holding device are preferably installed in the substrate holding devices according to the invention. If several sensors are integrated into the substrate holding device along a radial path up to the substrate edge, the bonding wave can be monitored.

[0093] In an extended embodiment, small elevations, studs, pins, and / or ridges are located in a recess whose surface is congruent with the substrate receiving surface. In one embodiment, the ridges can also be designed to be lowered. In one embodiment, the substrate receiving surface can be designed at least partially from several annular and / or circular segments with studs and / or ridges, with individually controllable vacuum tracks and / or vacuum track segments for vacuum fixation of the substrates.

[0094] The preferred substrate holding device is mainly used as an upper substrate holding device, but can also be used on the underside of a bonding system for fixing the lower substrate.

[0095] All embodiments can be carried out in low vacuum, more preferably in high vacuum, in particular at a pressure of less than 100 mbar, preferably less than 10' 1 mbar, preferably less than 10' 3 mbar, with even greater preference less than 10' 5 mbar. However, in a vacuum environment, the bond wave velocity increases. Other embodiments can be operated at atmospheric pressure under an inert gas atmosphere.

[0096] By selecting a gas or gas mixture, for example, in the low-vacuum bonding chamber, the speed and extent to which the upper substrate can lower and / or expand are determined. Furthermore, the properties of the gas can also control the speed of the bonding wave.

[0097] The lower and / or upper substrate is preferably radially symmetric. Although the substrate can have any diameter, the diameter of the substrates is in particular 1 inch, 2 inches, 3 inches, 4 inches, 5 inches, 6 inches, 8 inches, 12 inches, 18 inches, or greater than 18 inches. The thickness of the first and / or second substrate is between 1 μm and 2000 μm, preferably between 10 μm and 1500 μm, more preferably between 100 μm and 1000 μm.

[0098] In special embodiments, a substrate may also have a rectangular shape, or at least a shape that deviates from a circular shape. In the following, a substrate is also understood to mean a wafer.

[0099] Furthermore, it is preferably provided that only one vacuum segment is provided in the end section or that several vacuum segments are formed. This advantageously makes it possible to concentrate the holding effect of the vacuum specifically on the end section. In a preferred embodiment, the invention relates to an upper substrate receiving device for receiving the upper substrate, comprising movable segments with fixing elements for fixing the substrate and at least two flexible sealing lips for fixing the substrate at the edge, wherein the fixing elements can be grouped into at least two zones, in particular into circular and / or annular and / or ring-segment-shaped and separately controllable zones that correspond to the movable segments.

[0100] In particular, it is provided that the substrate receiving device or another holding means of the device has a displaceable partial element in a section associated with the end section of the second substrate, which is preferably displaceable together with the first sealing element and the second sealing element. This also allows the size of the distance between the primary section and the secondary section to be specifically adjusted.

[0101] The present invention further provides an assembly comprising a first substrate and a second substrate, produced using a method according to the invention, preferably using a device according to the invention. All advantages and properties described for the device and method apply analogously to the assembly, and vice versa.

[0102] Further advantages, features, and details of the invention will become apparent from the following description of preferred embodiments and from the drawings. These show:

[0103] Figure 1a: a side view of an upper substrate receiving device according to a first exemplary embodiment of the present invention,

[0104] Figure 1b: a side view of an upper substrate receiving device according to a second exemplary embodiment of the present invention,

[0105] Figure 1c: a side view of an upper substrate receiving device according to a third exemplary embodiment of the present invention,

[0106] Figure 1d: a side view of an upper substrate receiving device according to a fourth exemplary embodiment of the present invention,

[0107] Figure 2a: a plan view of an upper substrate receiving device according to a fifth exemplary embodiment of the present invention,

[0108] Figure 2b: a plan view of an upper substrate receiving device according to a sixth exemplary embodiment of the present invention,

[0109] Figure 2c: a plan view of an upper substrate receiving device according to a seventh exemplary embodiment of the present invention,

[0110] Figure 3a: a side view of an edge area during the bonding process with non-reinforced vacuum fixation at the edge,

[0111] Figure 3b: a side view of an edge region during the bonding process with a remaining edge fixation by means of sealing lips in a first exemplary embodiment of the present invention, Figure 3c: a side view of an edge region during the bonding process with a remaining edge fixation by means of sealing lips in a second exemplary embodiment of the present invention,

[0112] Figure 4a-h: a side view of exemplary embodiments of sealing lips.

[0113] In the figures, identical components or components with the same function are marked with the same reference numerals.

[0114] Figure 1a shows a schematic side view of a first embodiment of a substrate receiving device, also referred to here as the upper substrate receiving device 1o, for a device for bonding a first substrate, also referred to here as the lower substrate, to a second substrate, also referred to here as the upper substrate. The upper substrate receiving device 1o has an opening in the form of a recess, in particular a bore for an actuator, in particular a movable pin 9, as well as fixing means 3 for fixing the upper or second substrate 2o (not shown). In order to be able to hold the upper or second substrate 2o longer on the upper substrate receiving device 1o or the substrate receiving device for the second substrate 2o, elastic and / or flexible sealing elements, in particular sealing lips 4, are used on the edge or on the outer circular ring segment of the holding surface of the upper substrate receiving device 1o.The sealing lips 4 can be constructed so as to be partially recessed into the holding surface of the substrate receiving device 1o.

[0115] The vacuum fixation by means of fixation means 3 from Figure 1a preferably comprises a plurality of vacuum channels, also referred to here as vacuum tracks, which emerge at the surface of the substrate receiving device or open into a corresponding opening on the surface. The vacuum tracks can preferably be controlled individually. In a preferred embodiment, a plurality of vacuum tracks are interconnected (not shown), wherein the individual vacuum tracks or the interconnected vacuum tracks can be controlled individually, i.e. can be evacuated or flooded separately. The individual vacuum tracks can thereby ensure fixation to the upper substrate receiving device on their own. Each fixation means, in particular each vacuum track, is preferably independent of the other vacuum tracks. This makes it possible to construct individually controllable vacuum channels. The openings of the vacuum channels are preferably designed in the shape of a circular ring.

[0116] In order to hold the end section, in particular to hold it longer than the fixing means outside the edge region, it is preferably provided that a vacuum segment is formed between the upper substrate 2o in the end section and the surface of the upper substrate receiving device 1o. In addition to the vacuum openings, which serve as fixing means in this embodiment, a sealing system is provided for the vacuum segment, by which a locally limited vacuum is generated between the upper substrate receiving device 1o and the upper substrate 2o.The vacuum channel or the interconnected vacuum channels, which are assigned to the vacuum segment and in particular open into the region of the surface of the upper substrate receiving device which forms part of the boundary of the vacuum segment, can preferably be controlled independently of the other fixing means, in particular other vacuum paths or vacuum channels, in order to control the vacuum segment preferably in a targeted manner independently of other fixing means, in particular when the effect of the other fixing means has already been canceled for the purpose of the bonding process. This makes it possible, for example, to still hold the end section even if the other fixing means no longer hold the second substrate 2o due to the upper substrate 2o being dropped. In particular, it is provided that no sealing system is provided for the regions outside the end section, i.e. regions between a first contact point and the end section.In particular, the sealing system formed on the outer edge of the upper substrate receiving device ensures that the force acting on the vacuum is greater than in the other areas between the upper substrate receiving device 1o and the upper substrate 2o.

[0117] In a preferred embodiment, a vacuum track 5 for the vacuum supply for the area between (each) two sealing lips 4 can be individually controlled, i.e. can be evacuated or flooded separately. This makes it possible to set up individually controllable vacuum tracks, each for fixing the upper or second substrate in the area of ​​the sealing lips 4 in the outermost area of ​​the upper substrate receiving device 1o, and for fixing 3 the upper substrate 2o in the inner annular area or outside the sealing lips. The vacuum is better maintained between the flexible and / or elastic and / or bendable sealing lips and the upper or second substrate 2o, so that the upper substrate 2o, in particular its end section, remains fixed to the outermost edge of the upper substrate receiving device 1o despite being released in the inner area of ​​the substrate holding surface. The upper substrate 2o is therefore still held at the edge orfixed in the end section and held there.

[0118] The area at the edge of the outer substrate holding surface in which the sealing lips are located has an extension in the radial direction which is not greater than 8 cm, preferably not greater than 4 cm and in particular not greater than 2 cm, measured from the outer edge of the upper or second substrate 2o.

[0119] Figure 1b shows a schematic side view of a second embodiment of an upper substrate receiving device 1o. The upper substrate receiving device 1o has an opening in the form of a bore for an actuator, in particular a movable pin 9, as well as fixing means 3 for fixing the upper substrate 2o. The substrate receiving device 1o has a displaceable sub-segment 6 and a concentrically arranged, rigid, non-displaceable sub-segment 7. The sub-segments 6, 7 are preferably circular ring segments.

[0120] In a preferred embodiment according to Figure 1b, the upper substrate receiving device 1o comprises a circular, movable sub-segment 6 on which the flexible sealing lips 4 are formed, so that the outermost edge or end section of the upper or second substrate 2o can also be moved toward the lower substrate 2u (not shown). By reducing the distance of the end section of the second substrate 2o, the air outlet velocity between the substrates 2o, 2u is reduced, and thus the bond wave velocity is also reduced.

[0121] The holding surfaces of the displaceable sub-segment 6 and the non-displaceable sub-segment 7 of the upper substrate receiving device 1o are congruent in the initial position of the displaceable segment 6, for the full-surface reception of the upper substrate 2o. The displaceable sub-segment 6 can be moved before and / or during and / or after bonding in the direction of the lower substrate receiving device or the lower substrate 2u.

[0122] The separately controllable vacuum track 5 for the area between two sealing lips is integrated into the movable sub-segments 6 of the upper substrate receiving device 1o. The movable sub-segment 6 with the associated vacuum tracks and / or vacuum segments 3, 5 is preferably designed in a circular ring shape. In particular, it is provided that the non-movable sub-segment, several non-movable sub-segments, or all non-movable sub-segments are free of a sealing system. Thus, unlike the movable sub-segment assigned to the end section, they are not designed to form a vacuum segment.

[0123] The displaceable outer sub-segment 6, which is associated with the end portion of the second substrate 2o, has a radial width of between 0.5 cm and 5 cm, preferably between 1 cm and 4 cm, more preferably between 1.5 cm and 3 cm. In particular, the displaceable outer annular sub-segment 6 has a width of 2 cm.

[0124] The distance between the first substrate, in particular a primary section, and the second substrate, in particular a secondary section, in the end section of the substrates to be bonded can be set immediately before bonding and / or during bonding, in particular to less than 0.1 mm, preferably less than 50 pm, more preferably less than 10 pm, most preferably less than 1 pm, most preferably less than 0.5 pm.

[0125] In particular, the distance between the substrates in the end section can be continuously reduced after contacting by moving the displaceable segment 6. In a further embodiment (not shown), the inner sub-segment 7 can be a circular ring-shaped depression without fixing means. In a further embodiment (not shown), the inner sub-segment 7 can be a holding surface provided with pins and / or knobs and / or webs, with or without fixing means. Figure 1c shows a schematic side view of a third embodiment of an upper substrate receiving device 1o. The substrate receiving device 1o has a plurality of sub-segments 6, 6' that can be moved independently of one another. The sub-segments 6, 6' are preferably circular ring segments. The centrally located sub-segment 7 is preferably circular ring-shaped and is not displaceable.

[0126] The displaceable outer sub-segments 6, 6' each have a width between 0.5 cm and 5 cm, preferably between 1 cm and 4 cm, more preferably between 2 cm and 4 cm.

[0127] Figure 1d shows a schematic side view of a fourth embodiment of an upper substrate receiving device 1o. In the embodiment according to Figure 1d, the upper substrate receiving device 1o contains a wider, circular, movable sub-segment 6 compared to the embodiment of Figure 1b, on which three flexible sealing lips 4 are located. In a further embodiment of the movable sub-segment 6, more than two sealing lips can be integrated into the sub-segment 6 to further strengthen the fixation of the upper substrate 1o in the end section.

[0128] The separately controllable vacuum tracks 5, 5' for the areas between two sealing lips 4 are integrated in the movable sub-segment 6 of the upper substrate receiving device 10. The movable sub-segment 6 with the vacuum tracks 3, 5, 5' is preferably designed in a circular ring shape.

[0129] The displaceable outer annular sub-segment 6 has a width which assumes a value between 1 cm and 8 cm, preferably between 2 cm and 6 cm, more preferably between 2 cm and 4 cm.

[0130] The shape of the holding surface of the substrate receiving device 1o is circular in a plan view according to Figure 2a, corresponding to the usual shape of the substrates. The upper substrate receiving device 1o has an opening in the form of a bore for an actuator, in particular a movable pin 9, as well as fixing means 3 and 5 (only shown in the enlarged view) for fixing the upper substrate 2o. The substrate receiving surface has a displaceable sub-segment 6 in the outer region of the substrate receiving device 1o, and a centrally located, rigid, non-displaceable sub-segment 7. The sub-segments 6, 7 are preferably circular ring segments. The separately controllable vacuum track 5 for fixing the second substrate 2o in the region 8 between two circular ring-shaped sealing lips 4 is integrated in the displaceable sub-segment 6 of the upper substrate receiving device 1o. The displaceable sub-segment 6 as well as the rigid orStationary sub-segments 7 can have further fixing means 3 for fixing the substrate. The vacuum fixing by means of fixing means 3 preferably comprises a plurality of vacuum tracks that exit or open at the surface of the displaceable and non-displaceable segments 6, 7 of the substrate receiving device 10. The vacuum tracks are preferably individually controllable. In a preferred embodiment, a plurality of vacuum tracks are combined (not shown), which in turn are individually controllable, i.e., can be evacuated or flooded separately. Each vacuum track is preferably independent of the other vacuum tracks. This makes it possible to construct individually controllable vacuum segments. The vacuum segments are preferably designed in a circular ring shape.In particular, the sealing system formed on the outer edge of the upper substrate receiving device ensures that the force acting on the vacuum in the region 8 is greater than in the other regions 6, 7 between the upper substrate receiving device 1o and the upper substrate 2o.

[0131] The holding surface of the upper substrate receiving device preferably consists at least or entirely of the holding surfaces of the segments 6 and 7. The diameter of the entire holding surface essentially corresponds to the diameter of the substrates to be bonded.

[0132] In a further embodiment, the inner sub-segment can be a circular ring-shaped depression. In a further embodiment, the inner sub-segment can be a holding surface provided with pins and / or knobs and / or webs, with or without fixing means. The webs can also be designed to be lowered compared to the plane defined by the holding surface. Figure 2b shows a schematic plan view according to a sixth embodiment of an upper substrate receiving device 1o. In the embodiment according to Figure 2b, four ring-segment-shaped flexible sealing lips or sealing strips 4 are located on the edge of the upper substrate receiving device 1o. In the figures, the ratios of the individual components are disproportionate. The features are not drawn to scale in order to better illustrate the function of the individual features.

[0133] The upper substrate receiving device 1o according to Figure 2b has an opening in the form of a bore for an actuator, in particular a movable pin 9, as well as fixing means 3 and 5 (only shown in the enlarged view) for fixing the upper substrate 2o. The substrate receiving surface has a movable sub-segment 6 in the outer region of the substrate receiving device 1o, and a centrally located, rigid, non-movable sub-segment 7. The sub-segments 6, 7 are preferably circular ring segments. The separately controllable vacuum path 5 for fixing the second substrate 2o in the inner region 8 of the ring-segment-shaped sealing lips 4 is integrated in the movable sub-segment 6 of the upper substrate receiving device 1o. The movable sub-segment 6 and the rigid or stationary sub-segment 7 can have further fixing means 3 for fixing the substrate.In particular, the sealing system formed on the outer edge of the upper substrate receiving device ensures that the force acting on the vacuum in the region 8 is greater than in the other regions 6, 7 between the upper substrate receiving device 1o and the upper substrate 2o.

[0134] Figure 2c shows a schematic plan view according to a seventh embodiment of an upper substrate receiving device 1o. In the embodiment according to Figure 2c, four ring-segment-shaped flexible sealing lips 4 are located on the edge of the upper substrate receiving device 1o. The upper substrate receiving device 1o according to Figure 2c is made up of four movable, separately controllable, ring-segment-shaped segments 6", 6'", 6 IV , 6 V at the edge and a non-movable segment 7 in the inner area. The substrate receiving surface thus has four movable, ring-segment-shaped sub-segments 6", 6'", 6 IV , 6 Vin the outer area of ​​the substrate receiving device 1o, and a centrally located, rigid, non-displaceable sub-segment 7. The four displaceable, ring-segment-shaped sub-segments 6", 6'", 6 IV , 6 V in the outer region of the substrate receiving device 1o form an outer circular ring. The ring-segment-shaped, movable sub-segments 6", 6'", 6 IV , 6 V There is a ring-segment-shaped, flexible sealing lip 4. The separately controllable vacuum path 5 for fixing the second substrate 2o in the inner region 8 of the ring-segment-shaped sealing lips 4 is in the displaceable sub-segment 6", 6'", 6 IV , 6 V the upper substrate receiving device 1o. The movable sub-segments 6", 6'", 6 IV , 6 Vas well as the rigid or stationary sub-segment 7 can have additional fixing means 3 for securing the substrate. In particular, the sealing system formed on the outer edge of the upper substrate receiving device ensures that the force of the vacuum in the areas 8 is greater than in the other areas 6", 6'", 6 IV , 6 V , 7 between the upper substrate receiving device 1o and the upper substrate 2o. With several ring-segment-shaped, movable, and separately controllable sub-segments, on which flexible sealing lips 4 are located, the outermost edge of the upper substrate can be moved selectively or in sections toward the lower substrate. By reducing the distance at the edge, the air outlet velocity between the substrates is reduced, thus also reducing the bond wave velocity.

[0135] In a further embodiment, at least two, preferably between 4 and 12, even more preferably between 4 and 8, displaceable, ring-segment-shaped, separately controllable sub-segments are present in the outer ring section. The ring-segment-shaped sub-segments, which together form an outer circular ring, can also have different sizes.

[0136] Figures 3a to 3c show a schematic illustration of the edge of the upper and lower substrate holding devices 1o, 1u and substrates 2o, 2u during a bonding process. The inner surface of the upper substrate 2o to be bonded lies opposite the inner surface of the lower substrate 2u to be bonded. The two substrate holding devices 1o and 1u were brought close to each other by positioning means (not shown) until the upper substrate 1o contacts the lower substrate 2u centrally to start the bonding process. The bonding wave 10 can propagate between the inner surfaces of the substrates 2o and 2u to be bonded.

[0137] Arranged on the lower substrate receiving device 1u are fixing means in the form of vacuum tracks 3, with which the lower, first substrate 2u can be fixed over its entire surface to the receiving surface. Figure 3a shows a section of the bonding process in the edge region of the substrates 2o, 2u as described in the prior art. The upper substrate 2o is dropped by releasing the fixing 3 from the upper substrate receiving device 1o. Due to the substrate sections of the stack already being bonded to one another, the desire to bond increases and the bonding wave 10 is accelerated. If the vacuum fixing of the upper substrate 2o at the edge is not removed, with the propagation of the bonding wave 10 and increasing bonding force, the bonding force ultimately prevails over the vacuum fixing force and the fixing to the upper substrate receiving device 1o is broken, and the upper substrate 2o falls and bonds over its entire surface to the lower substrate 2u.From the moment the upper substrate 2o is released from the upper substrate holding device 1o, the upper substrate 2o no longer has contact with the upper substrate holding device 1o, and the bonding wave speed can no longer be controlled. The distance between the primary section of the first substrate 2u, which is still to be bonded, and the secondary section of the second substrate 2o, which is still to be bonded, as well as the propagation of the bonding wave, can then no longer be controlled.

[0138] To prevent this, additional sealing lips 4 are preferably located on the edge of the upper substrate holding device 1o according to Figure 3b. In order to be able to hold the upper substrate 2o on the upper substrate holding device 1o for longer and thereby influence the bond wave speed, elastic and / or flexible sealing lips 4 are used on the edge or on the outer circular ring segment of the holding surface of the upper substrate holding device 1o, preferably only in the edge associated with the end section. The sealing lips 4 are partially recessed into the holding surface of the substrate holding device 1o. Thanks to the two additional sealing lips 4, the upper substrate 2o is in contact with the upper substrate holding device 1o for longer. The gap between the upper substrate 2o and the lower substrate 1o is actively influenced and can be controlled by bringing the substrate holding devices 1o, 1u closer together.At least one separately controllable vacuum track is assigned to the sealing lips 4, in particular to form a vacuum segment 5 during operation for securing the substrate in the region between the two sealing lips 4 in addition to securing it via the vacuum tracks 3. The elastic and / or flexible sealing lip 4 can be compressed or stretched without losing contact with the upper substrate 2o, even though the upper substrate 2o is already convexly curved in the center, contacts the lower substrate 2u, and the bonding wave 10 propagates. The sealing lips 4 allow the securing at the edge, particularly in the region between the two sealing lips 4, to be maintained for longer, and there is no premature vacuum interruption at the edge, which would lead to the upper substrate falling completely.

[0139] Figure 3c shows a section of the bonding process in the edge region of the substrates 2o, 2u. In this preferred embodiment of the upper substrate receiving device 1o according to Figure 1b, the upper substrate receiving device 1o contains a circular, movable sub-segment 6, on which at least two flexible sealing lips 4 are located, so that the sub-segment 6 of the upper substrate 2o can also be moved in the direction of the lower substrate 2u. The better fixation at the edge by means of sealing lips and the simultaneous approach at the edge in the direction of the lower substrate 2u reduce the pressure on the upper substrate 2o. The controlled reduction in distance at the edge of the substrates via the movable sub-segment 6 and the fixation of the upper substrate 2o at the edge reduce the air outlet speed between the substrates 2o, 2u and thus also reduce the bonding wave speed in a targeted and controlled manner during the bonding process.This results in less or hardly any, or even better, no distortions at the edges and edge defects.

[0140] The displaceable outer sub-segment 6 has a width between 0.5 cm and 5 cm, preferably between 1 cm and 4 cm, more preferably between 1.5 cm and 3 cm. In particular, the displaceable outer ring section has a width of 2 cm.

[0141] The distance between the substrates at the edge or in the end section can be set immediately before bonding and / or during bonding, in particular to less than 0.1 mm, preferably less than 50 μm, even more preferably less than 10 μm, most preferably less than 1 μm, and most preferably less than 0.5 μm. In particular, the distance between the substrates at the edge can be continuously reduced after contacting. Figures 4a-h show a side view of exemplary embodiments of sealing lips.

[0142] The preferably at least two sealing lips are set back with respect to the holding surface of the upper substrate receiving device, for example as shown in Figure 3c, so that only part of the sealing lip is located outside the holding surface. Advantageously, the sealing lip can be guided in a groove and (partially) countersunk in the upper substrate receiving device. The countersinking allows simple fixing and, at the same time, expansion of the elastic sealing lips. The exact design depends, among other things, on the selection of the shape and material of the individual sealing lips. The sealing lips are designed such that, when the upper substrate is fully suctioned or fixed, no stress is exerted on the substrate at the start of the process. All designs have in common that the elastic and / or flexible sealing lip can be compressed or stretched without losing contact with the substrate.

[0143] Reference symbol:

[0144] 1o upper substrate receiving device

[0145] 1 u lower substrate receiving device

[0146] 2o second substrate / upper substrate

[0147] 2u first substrate / lower substrate

[0148] 3 fixing elements

[0149] 4 Sealing lip / sealing ring / sealing strip

[0150] 5.5' Outer fixing elements

[0151] 6, 6' movable sub-segment

[0152] 6", 6'" movable sub-segment

[0153] 6 IV , 6 V movable sub-segment

[0154] 7 fixed sub-segment

[0155] 8 stronger fixing area between two sealing rings

[0156] 9 Deformation pin

[0157] 10 Bond wave

Claims

Claims 1 . Method for bonding a first substrate (2u) to a second substrate (2o), wherein the first substrate (2u) has a primary section and the second substrate (2o) has a secondary section, wherein during bonding of the first substrate (2u) to the second substrate (2o) a bonding wave (10) advancing along a bonding direction between -- a first section in which the first substrate (2u) and the second substrate (2o) are connected, and -- a second subsection in which the first substrate (2u) and the second substrate (2o) are still to be connected, wherein a subregion of the second substrate (2o) in the second subsection is offset in height relative to a subregion of the second substrate (2o) in the first subsection in a direction perpendicular to a main extension plane (HSE), and wherein, in order to maintain a distance between the primary section and the secondary section, the second substrate (2o) in the second subsection is held, preferably locally limited, in an end section facing away from the bonding wave during bonding.

2. Method according to one of the preceding claims, wherein by means of holding the end portion, a bonding speed at which the bonding wave (10) moves along the bonding direction during bonding is controlled.

3. The method according to claim 1, wherein the end portion is held at least for a period of time in which the bonding is at least 70%, preferably at least 80% and particularly preferably at least 90% complete, and / or wherein the end portion is held when the region of the second substrate (2o) between the end portion and the bonding wave is dropped.

4. Method according to one of the preceding claims, wherein, for holding the end portion, a vacuum is generated in a vacuum segment which preferably extends circumferentially and / or is closed by a sealing system.

5. Method according to one of the preceding claims, wherein, in order to adjust the distance between the primary section and the secondary section, the second substrate (2o) is displaced at least in regions during the bonding of a sub-segment which is assigned to the end section of the second substrate (2o).

6. Method according to one of the preceding claims, wherein the second substrate (2o) is held in the end section during bonding with a force which is greater than forces, in particular fixing and / or deformation forces, acting on other regions of the second substrate (2o).

7. Method according to one of the preceding claims, wherein, in addition to holding the end section for the relative alignment of the primary section and the secondary section to one another, in particular with respect to a direction running substantially parallel to the bonding direction, a first curvature of the first substrate (2u) and / or a second curvature of the second substrate (2o) is modified by means of a deformation system in a region adjacent to the bonding wave (10) and / or in a region encompassing the bonding wave (10).

8. The method according to claim 7, wherein during bonding by means of the deformation system, a difference between the first curvature and the second curvature along the bonding direction is kept substantially constant at least in sections.

9. Device for bonding a first substrate (2u) to a second substrate (2o), in particular by means of a method according to one of the preceding claims, wherein the first substrate (2u) has a primary section and the second substrate (2o) has a secondary section, wherein the device is configured such that during bonding of the first substrate (2u) to the second substrate (2o) a bonding wave (3) advancing along a bonding direction between -- a first section in which the first substrate (2u) and the second substrate (2o) are connected, and -- a second section in which the first substrate (2u) and the second substrate (2o) are still to be connected, is formed, wherein a partial region of the second substrate (2o) in the second partial section is offset in height relative to a partial region of the second substrate (2o) in the first partial section in a direction running perpendicular to a main extension plane, wherein the device is configured such that in order to maintain a distance between the primary section and the secondary section, the second substrate in the second partial section is held in an end section facing away from the bonding wave.

10. Device according to claim 9, wherein at least one sealing system is provided on the device for holding the end section, wherein the sealing system is designed such that during bonding the vacuum segment is formed in a region enclosed by the sealing system, wherein the vacuum in the vacuum segment is controllable independently of fixing means.

11. Device according to claim 9 or 10, wherein the sealing system is integrated into a substrate receiving device (1o) for holding the second substrate (2o) and / or the vacuum opening is embedded in the substrate receiving device (1o) for the second substrate (2o).

12. Device according to one of claims 9 to 11, wherein the sealing system, in particular a first sealing element and / or a second sealing element, is integrated in the substrate receiving device (1o) in an at least partially retractable manner.

13. Device according to one of claims 10 to 12, wherein the device has a displaceable sub-segment (6) in a region associated with the end portion of the second substrate (2o).

14. Device according to claim 13, wherein the displaceable sub-segment (6) comprises a sealing system.

15. Arrangement of a first substrate (2u) and a second substrate (2o) produced by a method according to one of claims 1 to 8, preferably with a device according to one of claims 9 to 14.

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