Method and device for influencing junction waves during junction

Abstract

The present invention relates to a method and apparatus for influencing bonding waves during the bonding of a substrate.

Description

Technology Field

[0001] The present invention relates to a method and apparatus for influencing bonding waves during the bonding of substrates. Additionally, the present invention relates to a method and apparatus for bonding a substrate holder comprising at least one zone. Such a zone is essential for processing, fixing, and bonding the substrate individually with another substrate or substrate stack in some apparatuses and methods. Background Technology

[0002] In the prior art, there are numerous publications describing substrate holders for fixing substrates. Some of these substrate holders are used in the process of connecting two substrates, so-called bonding. So-called fusion and direct bonding are particularly important in the bonding process. In fusion bonding, two substrates are bonded together solely with the help of hydrophobic or hydrophilic substrate surface properties. In the first process step, the so-called pre-bond, contact between the two substrates occurs specifically at the center point. After contact, the fixation of at least one, particularly the upper substrate, is released, and the two substrates are bonded together along the substrate surfaces facing each other. The bonding process occurs through a progressive bonding wave that starts at the point of contact and propagates outward toward the periphery of the two substrates. Even after this bonding process, it is still possible to separate the two substrates using appropriate methods and devices. Separation is necessary when it is found that the substrates are not bonded in an optimal manner. The substrates have untreated substrate surfaces. In most cases, the substrates have already been treated and contain different structures. Switching circuits (English: Integrated circuits), microprocessors, LEDs, MEMS, etc., can be considered. Then, the structure must be aligned with the structure of the second substrate and combined with the latter. Above all, it is important that each individual structure of the first substrate is correctly aligned and combined with the structure on the second substrate on the opposite side.

[0003] After producing the pre-bond, heat treatment of the produced substrate stack is typically performed to increase the adhesion between the two substrate surfaces. Once this heat treatment is completed, we speak of fusion or permanent bonding. From this point on, the two substrates can no longer be separated from each other without destruction.

[0004] Due to the propagation of junction waves, individual substrate regions may become distorted near the waves, and alignment accuracy between structures on opposite sides is no longer maintained. In particular, if multiple such distortions occur, they can lead to overall distortion, which increases towards the periphery and specifically starts at the center. In extreme cases, the distortion may be anisotropic, meaning it varies according to direction.

[0005] Accordingly, the industry has developed numerous substrate holders with the purpose of influencing junction waves. Control or regulation is preferably achieved through fixed elements, which allow the substrate to be secured to the substrate holder. For example, published documents WO2017162272A1, WO2018028801A1, or WO2019057286A1 describe possible methods for influencing junction waves through zones of a zone substrate holder. A zone is understood to mean a zone comprising at least one, possibly multiple, fixed elements. Zones may generally be physically separated from one another, but they may also be zones where the fixed elements are switched according to a predefined plan.

[0006] In particular, the substrate holder may also generally comprise only a single zone in which multiple fixing elements exist. However, a substrate holder having multiple zones separated from one another by a separating wall is particularly preferred. In the case of a substrate holder having only a single zone, the outer periphery may be regarded as a separating wall in the sense of the invention, which separates the single zone from the surrounding zone.

[0007] A vacuum substrate holder is a type of substrate holder. The space between the substrate and the substrate holder is vacuumed through fixing elements, which are mostly small holes, and atmospheric pressure presses the substrate into the holder to secure it. Initially, very simple fixing elements were formed by drilling only individual holes in the substrate holder. The entire area between the substrate and the surface of the substrate holder is vacuumed. All existing fixing elements are connected to the same vacuum line. When a vacuum is applied, the entire surface of the substrate is fixed, making it impossible to control or adjust locally.

[0008] As a substrate holder is developed and individual fixing elements can be controlled, fixing can be controlled or adjusted in a locally resolved manner.

[0009] Further development of the substrate holder consists of combining fixing elements and zones with a stud substrate holder (English: pin chuck). A stud substrate holder is a substrate holder that is milled at multiple locations, particularly symmetrically distributed. Milling out does not occur across the entire surface, but is preferably symmetrically performed along radial, azimuthal, or rectangular lines. Thus, elevation is maintained between these lines for the milled-back zones, which are referred to as studs in the prior art. By placing the substrate on these studs, while somewhat complete support is still achieved, the contact zone is significantly reduced. Furthermore, the intermediate spaces of the studs can be left empty, which equalizes the contact pressure from the surrounding atmosphere. In particular, a more uniform force effect on the substrate can be obtained by using multiple fixing elements per zone, with the stud density also being a function of location, and especially a function of radius. As a result of the milled studs, a recessed structure is generally formed that is identical to the zones. Adjacent zones are separated from each other by a separating wall. The separating wall is made of a material that is not milled back or is intentionally introduced, particularly a polymer seal. The separation wall completely surrounds the zone, and in the case of a vacuum substrate holder, it can be considered as vacuum sealing. The problem to be solved

[0010] The problem with the conventional technology lies in the fact that when a junction wave travels along the separation wall of a zone, adjacent zones or separated zones are generally evacuated with different intensities. Therefore, when a junction wave travels along the separation wall of two zones, a significant pressure gradient acts on the junction wave. The pressure gradient causes significant distortion between the substrates.

[0011] In this regard, the problem that a pressure gradient exists between a single zone and a surrounding zone even when the substrate holder has only one zone also exists in the prior art. In this case, the separation wall of the substrate holder is a peripheral part that simultaneously separates the surrounding zones. When a junction wave propagates from the edge of such a substrate holder, the same problem as when passing through a separation wall that separates multiple zones occurs, and the substrate zone close to the junction wave may be distorted. means of solving the problem

[0012] Therefore, the objective of the present invention is to eliminate, at least partially, the disadvantages mentioned in the prior art, particularly completely. The objective of the present invention is to specify an improved method and apparatus for bonding. Furthermore, the objective of the present invention is to specify a method and apparatus capable of improving bonding results. In particular, distortion between two substrates can be reduced.

[0013] The problem in question is resolved by the features of the adjusted claim. Advantageous developments of the invention are given in the sub-claims. Any combination of at least two features specified in the description, claims, and / or drawings is also within the scope of the invention. In the case of specified value ranges, values ​​within the specified limits shall be deemed disclosed as limited values ​​and may be claimed in any combination.

[0014] Accordingly, the present invention relates to a method for influencing a bonding wave during bonding of a first substrate and a second substrate, wherein at least one first substrate is fixed to a first substrate holder having at least one zone, and each of the at least one zone includes a separating element that at least partially forms the surface of the substrate holder, and the at least one separating element separates at least one zone from an additional zone or a peripheral zone of the first substrate holder, and each of the at least one zone includes at least one fixing element, and each of the at least one fixing element provides a holding force for fixing the first substrate to the first substrate holder, wherein the method comprises at least: i) a step of initiating a bonding wave by bringing the second substrate into contact with the first substrate, and then ii) a step of adapting.

[0015] The holding force of at least one fixed element in at least one zone is converted into the holding force of an additional fixed element in a zone located immediately ahead of it in the direction of propagation of the junction wave, or into the surrounding pressure of the surrounding zone.

[0016] In other words, at least one zone is controlled by adjusting the holding force of the fixing element of the substrate holder, in a manner that ensures the pressure gradient of at least one zone is as small as possible in the direction of propagation of the junction wave, particularly in the zone of the separation element. If the holding force of at least one fixing element is adjusted to the ambient pressure, particularly the pressure in the last zone in the direction of propagation, it is ensured that the atmospheric pressure at the moment when the junction wave passes through the separation wall at the edge of the substrate holder during junctioning is adjusted to match the holding force of the zone at the outer edge.

[0017] At least one, and specifically the pressure within the last zone, can adapt to the ambient pressure. Since pressure adaptation within the zone can occur more quickly and efficiently than pressure changes in the large chamber or surrounding zones, it favorably affects the junction wave. In particular, the holding force on the underlying substrate is reduced or completely eliminated, allowing it to spread unhindered at the edges.

[0018] At least one zone preferably includes a plurality of controllable fixed elements, wherein the holding force can be varied in a desired manner. Thus, it is possible to generate a holding force gradient within at least one zone, thereby enabling better control of the propagating junction wave still within at least one zone. The initiation of the junction wave preferably involves centrally contacting the second substrate with the first substrate so that the propagation of the junction wave occurs radially symmetrically.

[0019] A substrate holder having multiple zones, namely at least one zone and at least one additional zone, is particularly preferred. Accordingly, in the course of the following description, specific examples of a substrate holder having multiple zones are often described, wherein at least one separating wall is present to separate the two zones from each other. In the case of an alternative embodiment of the method using a substrate holder having only one zone, where the outermost separating wall simultaneously represents the periphery of the substrate holder and there is no second zone but instead an adjacent periphery zone, the holding force of the last zone or the outermost zone is preferably adjusted to enable particularly uniform crossing of the last or outermost separating wall. The separating wall may also be an inserted element, in particular a sealing lip. Thus, the separating wall does not necessarily have to be produced in a milled zone of the substrate holder but may be a mounted component. In particular, the pressure of the outermost zone is adjusted to match the periphery pressure.

[0020] The zone can be divided into multiple segments perpendicular to the propagation direction of the bond wave. Thus, multiple isosceles trapezoidal segments can form the zone, wherein each segment again preferably includes at least one fixed element. Regardless of the radial position, adaptation of the bond wave can therefore preferably occur simultaneously at multiple points along the circular substrate holder. Adaptation occurs after the start of the bond wave, and preferably in each case in the zone where the bond wave propagates (where the first and second substrates are in contact or bonded). In this way, bonding without distortion is possible.

[0021] In a preferred embodiment of the alignment method, during the adaptation of step ii), the ambient pressure is provided to adapt to the holding force of the fixing element of at least one zone. In this regard, the dominant atmospheric pressure or ambient pressure is adapted in the bonding chamber.

[0022] Since ambient pressure acts on the first substrate, the holding force can be advantageously controlled indirectly in at least one zone.

[0023] In a preferred embodiment of the alignment method, the adaptation of step ii) is provided such that the holding force in the direction of propagation of the coupled wave is equal immediately before and immediately after at least one separation element. In other words, by adapting the holding force in the separation element zone as the coupled wave passes, distortion-free coupling is ensured to be performed even in the zone transition zone. The holding force can also be continuously adapted. For the control of the coupled wave, it is important that the large difference in holding force in the desired zone is minimized immediately before and after the coupled wave crosses the separation wall. In this way, distortion in the zone transition zone can be advantageously ensured.

[0024] In a preferred embodiment of the alignment method, after the coupling wave is initiated in step i), the position of the coupling wave is continuously verified, and the adaptation of the holding force of at least one zone is made such that the holding force before and after at least one separation element is the same while the coupling wave crosses over at least one separation element. By determining the position of the coupling wave, the adaptation in step ii) can be made precisely at the time when the coupling wave moves over the separation element. In this way, the coupling wave can be controlled without causing distortion in the zone transition zone by implementing a desired difference in holding force between the zone outside the separation element and the latter.

[0025] In a preferred embodiment of the alignment method, at least one fixing element of at least one zone is configured as a vacuum fixing element, and at least one separating element is provided to fluidly separate at least one zone from an additional zone or surrounding zone. Particularly preferably, the substrate holder is a vacuum zone substrate holder, which is divided into a plurality of adjustable vacuum zones arranged symmetrically in the radial and propagation directions. The substrates arranged in the separating elements are thus suctioned and fixed. The holding force of the vacuum fixing is advantageously adjusted individually in each zone (or segment) because the latter is fluidly sealed and suitable for vacuum. In this way, the fixing element can act over the entire zone, and full surface control of the junction wave is achieved. The substrate holder can be rinsed, particularly with an inert gas, preferably helium. Additionally, the vacuum line may be rinsed with an inert gas.

[0026] In a preferred embodiment of the alignment method, the adaptation in step ii) is provided to occur by the flooding or evacuation of at least one zone or the flooding or evacuation of a surrounding zone. In this way, the holding force can advantageously be provided easily and quickly along a wide zone. Additionally, the holding force can be adapted particularly quickly at the zone transition zone or the transition of the separation element zone, and then advantageously can be quickly adjusted to a desired holding force to control the coupling wave in the zone between the separation elements.

[0027] In a preferred embodiment of the alignment method, the adaptation of step ii) is provided to include determining a pressure difference between at least one zone and an additional zone or surrounding zone, wherein the pressure difference is leveled by the adaptation.

[0028] In this way, it is possible to ensure that a particularly small pressure gradient is maintained before and after the separating element, and that deformation during bonding is minimized. Additionally, instead of being vacuum-treated, the area in front of the separating element can be advantageously immersed.

[0029] In a preferred embodiment of the alignment method, the pressure in at least one zone is provided to be adjusted to the pressure in an additional zone. In this way, it is desirable to have sufficient time to accurately determine the location of the coupled wave and then adjust the pressure in the downstream zone in the direction of propagation.

[0030] In an embodiment of the alignment method, the holding force of at least one zone and an additional zone is provided to be adjusted to each other to equalize the pressure gradient. In this case, the additional zone also includes a corresponding fixed element having a variable holding force. Additionally, when the adjustment of the ambient pressure occurs in the last zone of the propagation direction, it may occur simultaneously with the holding force of at least one zone.

[0031] In addition, the present invention relates to a device for influencing a bonding wave during bonding of a first substrate and a second substrate, comprising a first substrate holder for fixing at least one first substrate in at least one zone, wherein the at least one zone comprises at least one separating element forming at least partially the surface of the substrate holder of the first substrate holder and at least one fixing element arranged in the at least one zone, and the at least one fixing element comprises a control unit for adjusting a holding force for fixing the first substrate to the first substrate holder and a holding force of at least one fixing element in the at least one zone, wherein the control unit is configured to match the holding force of at least one fixing element in the at least one zone to the holding force of a fixing element in another zone located immediately ahead of the latter in the direction of propagation of the bonding wave or to match the ambient pressure while the bonding wave is propagating.

[0032] Accordingly, the control unit is configured to equalize the holding force of at least one fixed element with the holding force of the upstream zone. In the alternative where the holding force adapts to ambient pressure, the holding force of the last zone surrounding the substrate holder adapts specifically to ambient pressure. In other words, the zone substrate holder is provided with a number of controllable fixed elements, wherein the fixed elements are controlled to provide optimal holding force during bonding before and after the separating wall separating the zones, thereby reducing distortion during transition. A first substrate with a side away from the second substrate is placed on a separating element that forms at least partially the surface of the substrate holder. By controlling the holding force before and after crossing the separating wall, bonding waves can propagate particularly uniformly and unimpededly in the zone of the separating wall. The undesirable effects caused by different holding forces before and after the separating wall are consequently reduced, particularly for bonding waves propagating from the inside out. To control bonding waves, holding forces acting with different intensities between zones may be desirable. If the bonding process does not start from the center, the outer zones with fixed elements having variable holding forces may also be positioned closer to the center of the substrate holder. In the direction of the expected coupling wave, it is important to equalize the effect of the holding force acting differently (before and after the separation wall) by adjusting the holding force of the next zone, especially in the separation element zone. Thus, it is possible to ensure a desirablely small distortion in the separation element zone.

[0033] Dependency can be determined based on empirical or initial tests and adjusted accordingly. The control unit is not limited to simple control and may also adjust the holding force according to additional parameters (e.g., junction wave position). The holding force of the fixed element can preferably be adjusted by the control unit. Additionally, the substrate holder preferably includes a plurality of separating elements, which in turn can preferably be separated into a plurality of segments along the circular substrate holder. Since the segments of the periphery-distributed zone are aligned particularly along the direction of propagation, for example, trapezoidal segments become larger in the periphery direction. Overall, stress and distortion, particularly in zone transition zones or from the inside to the outside zone, can be advantageously minimized through this device. The control unit may also adjust the respective holding force according to additional parameters.

[0034] In a preferred embodiment of a device for influencing bonding waves during bonding, the device is also provided to include means for adapting ambient pressure to a holding force in at least one zone. In this way, as ambient pressure acts on the first substrate, the bonding waves may be indirectly affected or the holding force may be adapted. If the fixing element is a vacuum fixing element operating with pressure, pressure equalization may occur, so that the runout of the bonding waves occurs particularly smoothly.

[0035] In a preferred embodiment of a device that affects bonding waves during bonding, a control unit is configured to adapt the holding force or ambient pressure of at least one fixing element after contact during bonding between a second substrate and a first substrate. In this way, the device or the control unit can perform the adaptation by considering the position of the bonding waves, particularly based on the empirical data of the control unit.

[0036] In a preferred embodiment of a device that affects bonding waves during bonding, a control unit is configured to determine the holding force of at least one fixed element in at least one zone via a sensor. The sensor is preferably placed in the zone of the separating element of at least one external and / or internal zone in each case. Additionally, a sensor that checks the ambient pressure is preferably provided. In this way, the control unit can advantageously adjust the adaptation of the holding force based on the actual value, thereby further reducing distortion.

[0037] In a preferred embodiment of a device that influences bonding waves during bonding, the control unit is configured to maintain the holding force of at least one fixing element in at least one zone and the holding force of at least one additional fixing element in an additional zone equally while bonding the first substrate and the second substrate. In this way, the bonding wave can perform a particularly smooth and distortion-free transition from the inner zone to the outer zone. The uniform holding force can be efficiently and uniformly adjusted, especially in multiple zones connected to one another. Thus, the bonding result is further improved, and small distortion is ensured while crossing the separation wall.

[0038] In a preferred embodiment of a device that influences a bonding wave during bonding, a control unit is provided to be configured to maintain the holding force of at least one fixed element in at least one zone and the holding force of at least one fixed element in an additional zone at the same magnitude directly in the zone of at least one separating element, and to maintain this when the aw bonding wave passes through at least one separating element. The position of the bonding wave is preferably determined by a measuring device, particularly preferably optically, and the adaptation time is adapted in an optimal manner to the position of the bonding wave. In this way, the control of the holding force between separating elements influencing the bonding wave can be advantageously and rapidly continued even after the separating element has passed. Furthermore, an even more improved bonding result can be obtained, particularly in the zone of the separating element.

[0039] In a preferred embodiment of a device for influencing bonding waves during bonding, at least one fixing element of an additional zone and at least one fixing element of at least one zone are configured as vacuum fixing elements, and a separating element is provided to fluidly separate the inner zone and the outer zone from each other. When a substrate is placed in the first substrate holder, the fixation of the substrate to the first substrate holder can thus be created extensively across the entire zone under pressure (compared to the atmosphere or surrounding zone). This holding force can advantageously be changed quickly and accurately in each zone. In addition, since contact with the substrate is not required to apply force, contamination of the first substrate can be kept small. The zones fluidly separated from each other and controlled by the vacuum fixing element are thus predetermined to be used in a device for influencing bonding waves.

[0040] In a preferred embodiment of a device that influences bonding waves during bonding, a control unit is provided to be configured to keep the pressure difference between the pressure of an additional zone and the pressure of at least one zone as small as possible during bonding, preferably to keep it equal. Pressure control is preferably achieved through pressure sensors placed in each zone. Thus, during bonding the first substrate and the second substrate, a uniform and distortion-free bond can be advantageously produced, particularly in the zone of the separation element.

[0041] In a preferred embodiment of a device that affects the bonding wave during bonding, the means for changing the ambient pressure in the control unit is configured to adjust the ambient pressure to the pressure of at least one zone immediately before and after the bonding wave passes through at least one separation element. The aforementioned effects and benefits of the outer zone are similarly applied to additional outer zones. Through a plurality of zones in the direction of propagation of the bonding wave, bonding can be performed particularly precisely, uniformly, and without distortion.

[0042] In the following, the outer zone is understood to mean at least one zone or area located downstream in the direction of propagation of the coupled wave. The inner zone is an additional zone or final zone where the ambient pressure is adjusted. The inner zone is a zone located upstream in the direction of propagation. The holding power of the downstream or at least one zone is preferably adjusted to the holding power of the upstream zone.

[0043] A particularly advantageous effect of the device and method for influencing junction waves during junctioning is that no distortion occurs between the two substrates near the separation wall, or only negligible distortion occurs. The separation wall separates the zones from one another. Therefore, a smooth, smooth, and distortion-free intersection of the junction wavefront through the separation wall is possible. In particular, distortion is reduced in the separation wall zone, and stress on the bonded substrate stack is reduced.

[0044] Another aspect is the fact that pressure must be continuously controlled and regulated in the zone immediately before, during, and after passing through the dividing wall. It is desirable to continuously change the pressure in the zone after the junction wave or in the zone where the junction wave is precisely located, in a manner that adjusts to the pressure in the zone through which the junction wave travels.

[0045] One aspect of the above apparatus and method is that the coupling wave is influenced by the control and adjustment of the zone's holding force along the propagation direction of the coupling wave initiated during the operation. By controlling / adjusting at least one fixed element, particularly by temporarily adjusting the pressure state of the zone, the velocity or acceleration of the coupling wave is adjusted in a desired manner. In particular, continuous and smooth passage of the coupling wave without distortion over the zone's separation wall is made possible.

[0046] In the following process, an idealized process is assumed and described to illustrate an exemplary method for coupling. In particular, it is assumed that the coupling wave propagates radially symmetrically from the point of contact to the periphery, that is, in a circular manner as much as possible. This approach facilitates the description of the method because it generally allows for the reference of the coupling wave that needs to be controlled. Generally, asymmetric propagation of the coupling wave can also be considered. However, all methods, devices, and approaches mentioned herein are considered with the fact that the coupling wave can generally propagate anisotropically and therefore zone control before and / or after the coupling wave segment must be taken into account. That is, zone control is generally adjusted to the individual coupling wave segments that must pass through the separation wall at specific locations.

[0047] The following description refers to the regulation. The regulation is understood to mean a process of obtaining a measurement signal for a first physical value and adjusting a second physical value according to the desired result. As can be imagined, for example, the position of the junction wave must be measured (first physical value) and the pressure in the zone before the junction wave and / or the pressure in the zone after the junction wave (second physical measurement value) must be adjusted, and by doing so, the desired result (minimal distortion of the substrate of the separation wall or of the substrates) is achieved.

[0048] In contrast, control is understood to mean merely verifying physical values ​​without the corresponding measurement signal. Therefore, when physical values ​​need to be adjusted to obtain results, this can be determined based on verified empirical data. For example, it is possible to know how junction waves operate on the same type of substrate under identical initial and boundary conditions. In this case, pressure can be controlled as a function of time in individual zones by proceeding from the contact time without measuring the ongoing junction wave.

[0049] The above method and apparatus are described based on a vacuum substrate holder. That is, the fixing device is a vacuum fixing device, specifically a simple hole drilled in the surface of the substrate holder, which can be vacuumed or immersed. Additionally, other fixing elements, such as electrostatic fixing devices and magnetic fixing devices, may be used. The latter is also divided into zones and is suitable for adjusting the holding force in each zone. In this case as well, the fixing element or holding force is variable / adjustable. Therefore, the term fixing element should be interpreted generally and relates not only to vacuum fixing but also to vacuum fixing.

[0050] In the first process step of an exemplary method for influencing bonding waves during bonding, a lower substrate is loaded into a lower substrate holder and an upper substrate is loaded into an upper substrate holder. The two substrates are preferably secured by a fixing element provided for this purpose.

[0051] In the second process step of the exemplary method for influencing bonding waves during bonding, the two substrates are aligned with each other. Alignment is preferably performed using an alignment system provided for this purpose. Alignment between the two substrates is preferably performed with the help of alignment marks located on the substrates. The alignment method and apparatus are not described in further detail.

[0052] In the third process step of the exemplary method for influencing bonding waves during bonding, the two substrates are brought closer together. The distance between the surfaces of the two substrates to be bonded together is less than 10 mm, preferably less than 5 mm, much more preferably less than 1 mm, most preferably less than 0.1 mm, and most preferably less than 0.01 mm.

[0053] The third process step may be performed first, and then the second process step may be performed.

[0054] In the fourth process step of the exemplary method for influencing the bonding wave during bonding, at least one of the two substrates is deformed so that contact occurs between the deformed substrate and the second substrate. It is preferable that the contact be made in a point shape as much as possible. It is preferable that the contact occur at the center as much as possible. The point of contact is the start of the bonding wave that subsequently propagates.

[0055] In the fifth process step of the exemplary method for influencing bonding waves during bonding, the fixation is switched or regulated in such a way that at least one substrate is deformed so that the bonding wave can begin to flow. The bonding wave preferably starts at the center of each substrate and propagates radially symmetrically. With the advancing bonding wave, additional fixation is switched or regulated so that the bonding wave continuously moves toward the periphery.

[0056] The sixth process step of the exemplary method for influencing the bonding wave during bonding generally occurs when the bonding wave section moves repeatedly and always toward the separation wall between zones. In this case, pressure is regulated in at least one zone, particularly the zone before and / or after the bonding wave section. Thus, the bonding wave section is a radially symmetric propagation zone where the upper and lower substrates are bonded. Regulation is performed in such a way that there is minimal, or specifically no, distortion between the substrate zones where the bonding wave section is located near the separation wall. To this end, the pressure in the zone before and / or after the bonding wave section is continuously regulated so that the bonding wave section is not affected by a pressure gradient or is affected by a very small pressure gradient.

[0057] In an embodiment of a device that influences bonding waves during bonding, the substrate holder includes a plurality of fixed elements. The fixed elements can be controlled individually. The fixed elements are preferably vacuum fixed. With the help of vacuum fixed elements, the contact pressure of the peripheral zone of the substrate can be controlled very easily and very precisely. The fixed elements are part of the zone. The zone can generally include a plurality of fixed elements, allowing for finer control of the bonding waves within the zone. Particularly in the case of a vacuum zone, the plurality of fixed elements enables faster evacuation of the zone to be performed. Since a larger volume of gas flow can be evacuated through the plurality of fixed elements within the zone, faster control is possible. Theoretically, it is conceivable that the fixed elements within the zone draw in gas at different speeds. In this case, a pressure gradient can be created within the zone. However, it is better and more convenient to change the pressure within the zone uniformly and isotropically. Therefore, the pressure within the zone preferably exists only as a function of time, and the plurality of fixed elements are preferably switched simultaneously so that the pressure within the zone is controlled uniformly and isotropically. Effects of the invention

[0058] A bonding device comprising at least one zone substrate holder, preferably at least one measuring device and at least one control unit. For adjustment, the measuring device measures physical parameters, e.g., the position determination of a bonding wave or at least a bonding wave section. The measuring device transmits this data to the control unit. The control unit evaluates the measurement and, based on the result, determines the physical parameters necessary to control and / or adjust the fixed element.

[0059] It is preferable that the measuring device be an optical system for determining the position of the junction wave. However, a sensor that determines the position of the junction wave electromagnetically can also be considered. For example, a proximity sensor can be considered.

[0060] The radius of curvature of the substrate at the junction wave point is also particularly interesting. In this regard, the control of the fixed element may be based on the radius of curvature of the substrate in the junction wave zone.

[0061] The control unit is a microchip, a computer, software, or a combination thereof. In most cases, it will be computer software. The measurement signal is transmitted to the computer via peripherals and evaluated by the software. The software then adjusts the fixing elements of the board holder via peripherals. The use of an electronically programmed PID controller for adjustment can also be considered.

[0062] Identical components or components with the same function are indicated by the same reference number in the drawings. Since all sketches can be drawn enlarged for representational purposes, the drawings do not need to have the proportions of the actual implementation.

[0063] Further advantages, features, and details of the present invention are indicated with the help of the following description of preferred embodiments and drawings. The latter are illustrated schematically. Brief explanation of the drawing

[0064] FIG. 1 is a plan view of an embodiment of a substrate holder of a device that affects junction waves during junctioning. FIG. 2a is the first state of the sixth process step of an exemplary method affecting bonding waves during bonding, FIG. 2b is the second state of the sixth process step of an exemplary method affecting bonding waves during bonding, FIG. 2c is the third state of the sixth process step of an exemplary method affecting bonding waves during bonding, FIG. 2d is the fourth state of the sixth process step of an exemplary method affecting bonding waves during bonding. Specific details for implementing the invention

[0065] Identical components or components with the same function are indicated by the same reference number in the drawing.

[0066] FIG. 1 shows the fixed surface of an embodiment of a substrate holder (1) of a device for bonding. The base body (2) can be mounted to the device with a fixing device (3). The substrate holder (1) includes a plurality of zones (7, 7', 7'') separated particularly in the radial and azimuthal directions. In this example, the zones (7, 7', 7'') are separated by a separating wall (10). The separating wall (10) is simply maintained in the same way as the stud (9) in the milling out of the base body (2). The substrate holder (1) may be configured such that the separating wall (10) is a polymer seal or a metal seal. In the drawing, a central radially symmetrical zone (7) can be seen. Furthermore, 16 zones (7', 7'') are arranged radially around the central zone (7) along the first and second circles, respectively.

[0067] Zones (7, 7', 7'') are particularly recessed, preferably milled, recesses (11), where studs (9) are located at multiple points. The pin surface of pin 9 specifically coincides with the web surface of the separating wall (10). Zones (7, 7', 7'') are specifically composed of vacuum zones. The recesses (11) can be evacuated independently of each other, particularly individually, and separated by the separating wall (10) through fixing means 12. The fixing element (12) is, in this simplest case, simply a drilled hole, through which the space between the studs (9) and zones (7, 7', 7'') can be evacuated or flooded. If zones (7, 7', 7'') are also used for deformation, fluid may be introduced through the fixing means (12), which specifically causes local deformation of the fixed substrate.

[0068] A deformation element (5) is preferably located in the center of the substrate holder (1), which can particularly deform the fixed substrate at the center. A stud (9) is used to particularly reduce the contact area of ​​the fixed substrate (4) and, preferably, prevents contamination.

[0069] A number of sensors (8), particularly pressure sensors, can be located in sections (7, 7', 7'') of the substrate holder (1).

[0070] Area Q can also be seen in the drawing, and its cross-sectional view is shown in another drawing.

[0071] It is also self-evident to those skilled in the art that pressure can be defined as force per unit area. Since a method of influencing junction waves using a vacuum substrate sample holder is described, and force is generated on the substrate by vacuuming the zone, it is advantageous to speak of pressure. Then, physical considerations regarding force and its effects must be performed according to the latest technology.

[0072] FIG. 2a shows the first state of the sixth process step of the method for influencing the bonding wave during bonding. A cross-section of region Q (see FIG. 1) is represented by two zones (7', 7'') and their separating wall (10). The lower substrate (4) is placed over the stud (9) and the separating wall (10), and the upper substrate (4)' is bonded precisely to the lower substrate (4) in this section of the two zones (7', 7''). The propagating bonding wave (6) can be seen. The bonding wave (6) is represented only as a point in the cross-section. In the plan view, the bonding wave (6) will preferably be a completely closed curve. Since the advancing bonding wave (6) must occur in a controlled or regulated manner, the two zones (7', 7'') generally have different pressures. For example, in this drawing, the pressure p1 of zone (7') is selected to be low so that the substrate region (13) of the lower substrate (4) can be fixed more strongly and better near the bonding wave (6), so that the substrate region (13') can be bonded to the upper substrate (4') without distortion as much as possible. Zone (7'') has a higher pressure p2, particularly close to the ambient pressure, so that the substrate region (13, 13') that is still further away from the bonding wave (6) can still be adapted.

[0073] A pressure diagram is shown at the bottom of the drawing. The horizontal axis indicates a location in any unit, preferably millimeters, and the vertical axis indicates a pressure value. Three pressures are shown. Meanwhile, the external ambient pressure is p0. In this case, it corresponds to approximately 11 bar. It is also conceivable that the substrate holder (1) is located in a chamber where the external pressure rises. Then, the ambient pressure becomes overpressure relative to the atmosphere.

[0074] It can be conceived that the substrate holder (1) is located in a chamber where external pressure is reduced. Then the ambient pressure will be lower than the atmospheric pressure. The above embodiment is particularly relevant when the substrate needs to be bonded in a low-pressure environment, for example, to prevent or reduce contamination.

[0075] In the following description, it is assumed that the device is exposed to the atmosphere and the surrounding pressure p0 is an atmospheric pressure of about 1 bar.

[0076] Generally, the ambient pressure p0 is between 2 bar and 0.1 bar, preferably between 1.5 bar and 0.5 bar, more preferably between 1.25 bar and 0.75 bar, most preferably between 1.10 bar and 0.90 bar, and most preferably exactly 1.0 bar.

[0077] The pressure in zone (7') is denoted as p1. Since zone (7') is exhausted very strongly, it has a correspondingly low pressure. The pressure in zone (7'') is denoted as p2. Since zone (7'') is exhausted with low intensity, it is higher than the pressure p1.

[0078] Pressures p1 and p2 are generally always below ambient pressure p0. In a very special embodiment, it is possible for at least one pressure to be above ambient pressure p0. In this case, the substrate area (13) of the substrate (4) below the area where the pressure is above ambient pressure p0 will be raised.

[0079] Since the bonding wave (6) is still sufficiently far from zone (7''), the pressure difference between the pressure p1 of zone (7') and the pressure p2 of zone (7'') does not cause unwanted distortion between the two substrate regions (13, 13'). However, in this process step, since the bonding wave (6) is moving toward the separation wall (10) using a lens, the pressure will soon change significantly, causing an intense effect on the bonding wave (6) and bonding behavior between the substrate regions (13, 13').

[0080] The values ​​of pressures p1 and p2 generally vary depending on the process and must be verified through testing and / or simulation.

[0081] FIG. 2b shows the second state of the sixth process step of the method for affecting the bond wave, where the bond wave (6) is already further advanced. In order to ensure that the substrate area (13) of the lower substrate (10) experiences the weakest possible pressure effect during the bond wave (6) crossing the separation wall (10), the pressure p1 in zone (7') and the pressure p2 in zone (7'') are already adjusted.

[0082] Since the transition from the first state according to FIG. 2a to the second state according to FIG. 2b occurs naturally and continuously, that is, pressures p1 and p2 are continuously adjusted while the bonding wave (6) proceeds continuously. Therefore, the goal is to ensure that the substrate regions (13, 13') are bonded to each other without error or with minimal error.

[0083] The new values ​​of pressures p1 and p2 generally vary depending on the process and must be verified through testing and / or simulation.

[0084] FIG. 2c shows the third state of the sixth process step of the method for influencing the bonding wave, where the bonding wave (6) is located on the separation wall (10). In the prior art, pressures of different intensities are applied to zones (7') and (7'') of the substrate region (13), causing a defective bond to occur between the substrate regions (13 and 13').

[0085] By increasing the support force or adjusting the pressures p1 and p2 in the zone (7', 7''), an optimal bonding process between the substrate regions (13, 13') is possible.

[0086] The values ​​of pressures p1 and p2 generally vary depending on the process and must be verified through testing and / or any simulation. Therefore, the pressures p1 and p2 shown as examples in the expression do not necessarily have to be identical, but must be adjusted so that the two substrate regions (13, 13') are joined in the most optimal way possible. Being joined in an optimal way means that all structures on the substrate surface of the substrate regions (13, 13') are correctly aligned and joined to each other.

[0087] FIG. 2d shows the fourth state of the sixth process step of the method in which the bonding wave (6) has moved over the separation wall (10). The substrate area (13, 13') is now in a new zone (7''). In this embodiment, as an example, the pressure p2 in zone (7'') can be adjusted back to a very low value to secure the lower substrate (10) while the bonding wave (6) proceeds to the end of zone (7''). The new values ​​of pressures p1 and p2 generally depend on the process and must be verified through testing and / or simulation.

[0088] The process shown in FIGS. 2a through 2d specifies that the fixed element (12) is switched during the intersection of the bonding wave (6) across the two zones (7', 7'') of the separation wall (10) so that the bonding between the substrate regions (13, 13') and, therefore, the bonding between the substrates (4, 4') in general is achieved in an optimal manner, that is, so that the structural deviation between the substrates (4, 4') facing each other is minimized. In the special case of the vacuum substrate sample holder (1), this means that the pressure of the zones (7', 7'') is controlled so that the substrate regions (13, 13') experience a pressure transition that is as continuous and smooth as possible during the intersection of the bonding wave (6) across the separation wall (10). That is, pressures p1 and p2 are as equal as possible and only slightly different from each other. Explanation of the symbols

[0089] 1: Circuit board holder 2: Base body 3: Fixing device 4: Substrate 5: Deformation element 6: Junction wave 7, 7', 7'': Zone, inner zone, outer zone, farther zone 8: Sensor 9: Stud 10: Separating elements, separating walls 11: Recess 12: Fixed element 13, 13': Substrate region Q: Cross-sectional region p0: Atmospheric pressure, ambient pressure p1, p2: Pressure in upstream zone / Internal pressure, Pressure in downstream zone / External pressure

Claims

Claim 1 - A first substrate (4) is fixed to a first substrate holder (1) having at least one area (7', 7''), and the at least one area (7', 7'') comprises, in each case, at least one separating element (10) that forms at least partially on the surface of the substrate holder; - the at least one separating element (10) separates the at least one area (7', 7'') from an additional area (7, 7') or a peripheral area of ​​the first substrate holder (1); - the at least one area (7', 7'') comprises, in each case, at least one fixing element (12), and in each case, at least one fixing element (12) provides a holding force for fixing the first substrate (4) to the first substrate holder (1), wherein the method comprises: i) a step of initiating the bonding wave (6) by contact between the second substrate (4') and the first substrate (4), and subsequently, ii) a method characterized by including the step of adapting the holding force of at least one fixed element of the at least one zone (7', 7'') to a) the holding force of a fixed element of an additional zone (7', 7'') located immediately ahead of it in the direction of propagation of the bonded wave (6) or b) the surrounding pressure of the surrounding area. Claim 2 A method according to claim 1, characterized in that during the adaptation of step ii), the ambient pressure is also adapted to the holding force of the fixed element (10) of the at least one zone (7''). Claim 3 A method according to claim 1, wherein the adaptation of step ii) is performed such that the maintaining force of the propagation direction of the coupled wave (6) is equal immediately before and immediately after at least one separating element (10). Claim 4 A method according to claim 1 or 2, characterized in that, in step i), the position of the joining wave (6) is continuously verified after the joining wave (6) starts, and the adaptation of the holding force of at least one zone (7', 7'') is made such that the holding force is the same before and after at least one separating element (10) while the joining wave (6) crosses at least one separating element (10). Claim 5 A method according to claim 1 or 2, wherein at least one fixing element (12) of at least one zone (7', 7'') is each configured as a vacuum fixing device and at least one separating element (10) fluidly separates at least one zone (7', 7'') from an additional zone (7, 7') or surrounding zone. Claim 6 A method according to claim 1 or 2, characterized in that the adaptation of step ii) is achieved through gas filling or vacuuming of at least one zone (7, 7') or surrounding area. Claim 7 A method according to claim 1 or 2, wherein the adaptation of step ii) includes the step of determining a pressure difference between at least one zone (7', 7'') and an additional zone (7, 7') or surrounding zone, wherein the pressure difference is equalized by the adaptation. Claim 8 A method according to claim 1 or 2, characterized in that the pressure (p2) of at least one zone (7'') is adjusted to match the pressure (p1) of an additional zone (7'). Claim 9 - A first substrate holder (1) for fixing a first substrate (4) to at least one zone (7', 7''), wherein at least one zone (7) comprises at least one separating element (10) that partially forms the substrate holder surface of the first substrate holder (1); - at least one fixing element (12) arranged in at least one zone (7) having a holding force for fixing the first substrate (4) to the first substrate holder (1); and - a control unit for adjusting the holding force of at least one fixing element (12) of at least one zone (7), wherein, while the bonding wave is advancing, the holding force of at least one fixing element of the at least one zone (7', 7'') is configured to adapt to a) the holding force of a fixing element of an additional zone (7', 7'') located immediately ahead in the propagation direction of the bonding wave (6) or b) the peripheral pressure of the surrounding area. Device. Claim 10 A device according to claim 9, further comprising means for adapting ambient pressure to a holding force of at least one zone (7', 7''). Claim 11 An apparatus according to claim 9 or 10, characterized in that the control unit is configured to maintain the holding force of at least one fixing element (12) of at least one zone (7', 7'') and the holding force of at least one additional fixing element (12) of an additional zone equally while joining the first substrate (4) and the second substrate (4'). Claim 12 A device according to claim 9 or 10, wherein the control unit is configured such that when a bonding wave (6) passes over the at least one separating element (10), the holding force of the at least one fixed element (12) separated by the separating element (10) and the holding force of the additional zone (7', 7'') are maintained at the same magnitude. Claim 13 A device according to claim 9 or 10, wherein at least one fixed element (12) of an additional zone (7, 7') and at least one fixed element (12) of at least one zone (7', 7'') are configured as vacuum fixing devices and a separating element (10) fluidly separates the inner zone (7') and the outer zone (7'') from each other. Claim 14 A device according to claim 9 or 10, characterized in that the control unit is configured to maintain the same pressure difference between the pressure (p1) of an additional zone (7, 7') and the pressure (p2) of at least one zone (7', 7'') during joining. Claim 15 A device according to claim 9 or 10, wherein the control unit is configured such that the means for controlling the ambient pressure is configured to control the ambient pressure to the pressure (p2) of at least one zone (7'') immediately before and after the bonding wave (6) passes through at least one separation element (10).

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