Method for joining substrates

Abstract

The present invention relates to a method for joining a first substrate (2) and a second substrate (2') at the contact surfaces (2o, 2o') of the substrates (2, 2'), comprising the following steps, particularly the following process: - using a holding force F H1 The first substrate (2) is held on the first sample holder surface (1o) of the first sample holder (1) with a holding force F. H2 The second substrate (2') is held on the second sample holder surface (1o') of the second sample holder (1'), and the contact surfaces (2o, 2o') are brought into contact at the engagement initiation site (20) and the second sample holder surface (1o, 1o') is heated to at least the heating temperature T. H The first substrate (2) is bonded to the second substrate (2') along a bonding wave extending from the bonding initiation site (20) to the side edges (2s, 2s') of the substrate (2, 2'), characterized in that the heating temperature T on the surface (1o') of the second sample holder is reduced during bonding. H .

Description

[0001] This application is a divisional application of the invention patent application filed on February 16, 2016, with application number 201680003082.2 (international application number PCT / EP2016 / 053270) and titled "Method for Bonding Substrates". Technical Field

[0002] The present invention relates to a method for bonding a first substrate to a second substrate according to claim 1. Background Technology

[0003] In the semiconductor industry, substrates have been aligned and interconnected for many years. This interconnection (so-called bonding) is used here to construct multi-substrate stacks. In such multi-substrate stacks, functional units, especially memories, microprocessors, and MEMs, are interconnected and thus combined. These combinations lead to a wide variety of application possibilities.

[0004] The density of functional units is increasing year by year. Due to forward-looking technological development, the size of functional units is being reduced more and more. Consequently, the increased density results in a larger number of functional units per substrate. This increase in the number of units is largely responsible for reducing the cost per unit.

[0005] The main drawback of increasingly smaller functional units is that it becomes increasingly difficult to achieve the following: that is, to achieve error-free, and especially, complete, superposition of all functional units along the bonding interface of the two substrates.

[0006] The biggest problem in current alignment techniques is therefore not always just about aligning two substrates, especially two wafers, with each other according to alignment marks; rather, it lies in achieving an error-free, especially complete, correlation between points on the first substrate and points on the second substrate, a correlation that extends to the entire surface of the substrates. Experience shows that the surface structures of the substrates after the bonding process are often not identical. Therefore, general (especially overall) alignment of the two substrates and the subsequent bonding steps are not always sufficient to achieve the desired complete and error-free alignment of points at every point on the substrate surface.

[0007] In the prior art, there are two fundamental problems that hinder the simple overall alignment and joining process.

[0008] First, the positions of the structures of the first and / or second substrates often deviate from their theoretical positions. This deviation can have a variety of causes.

[0009] For example, it is conceivable that the actual manufactured structure deviates from its ideal position because the manufacturing process (Herstellprozess) has errors or at least tolerances. An example of this might be the repeated application of lithography through a step-and-repeat process, which introduces small but significant errors in position with each translational shift of the stempel.

[0010] Another, less significant, reason could be the deformation of the substrate due to mechanical, but especially thermal, loads. The substrate, for example, has a defined temperature at the point in time when these structures are fabricated. This temperature typically does not remain constant throughout the entire process flow of the substrate, but rather varies. Thermal expansion occurs with temperature changes, resulting in a change in diameter in the most ideal case and complex thermal deformation in the most unfavorable case.

[0011] Secondly, even two substrates that possess this perfect, especially uniform, consistency shortly before contact and the actual bonding process may lose this consistency during the bonding process. Therefore, the decisive factor in producing a perfect substrate stack with structural uniformity lies in the bonding process itself.

[0012] Third, the layers and structures applied to the substrate may generate stress in the substrate. These layers may be, for example, insulating layers, such as through-silicon vias (TSVs).

[0013] One of the biggest technical challenges in permanently bonding two substrates is the accuracy of the alignment of functional units between the substrates. Although these substrates can be aligned very precisely with each other using alignment equipment, substrate distortion can occur during the bonding process itself. Due to this distortion, functional units may not be correctly aligned with each other at all locations. Alignment inaccuracies at specific points on the substrate can result from distortion, scaling errors, lens errors (magnification or reduction), etc. In the semiconductor industry, the entire scope of research into such problems is encompassed under the term "overlay accuracy." A relevant introduction to this topic can be found, for example, in Mack and Chris's "Fundamental Principles of Optical Lithography" (The Science of Microfabrication, WILEY, 2007, reprinted 2012).

[0014] Before the actual manufacturing process, each functional unit is designed in a computer. For example, printed circuit boards, microchips, MEMS, or any other structure that can be fabricated using microsystems technology are designed using CAD (computer-aided design) programs. However, during the fabrication of these functional units, it becomes apparent that there is always a deviation between the ideal functional unit constructed on the computer and the actual functional unit produced in the cleanroom. These differences are primarily attributed to hardware limitations, i.e., engineering issues, but very often to physical boundaries. Thus, the resolution accuracy of the structure fabricated by the photolithography process is limited by the size of the photomask aperture and the wavelength of the light used. Mask distortion is directly transferred to the photoresist. The linear motor of the machine can only approximate a reproducible position within a pre-defined tolerance, and so on. Therefore, it is not surprising that the functional units of the substrate are not exactly the same as the structure constructed on the computer. Consequently, all substrates already have a non-negligible deviation from the ideal state before the bonding process.

[0015] If we now compare the positions and / or shapes of two opposing functional units on the two substrates, assuming neither substrate has been distorted due to the bonding process, it is determined that there is often an imperfect fit between the functional units, because these functional units deviate from the ideal computer model due to the errors described above. The most common errors are shown in Figure 8 (reproduced from: http: / / commons.wikimedia.org / wiki / File:Overlay_typical_ model_terms_DE.svg(May 24, 2013), as illustrated in "Fundamental Principles of Optical Lithography" by Mack and Chris (The Science of Microfabrication, WILEY, p. 312, 2007, reprinted 2012). These illustrations allow for a rough distinction between global and local, or symmetrical and asymmetrical, overlay accuracy errors. Global overlay accuracy error is uniform and therefore independent of ort. This global overlay accuracy error arises from the same position-independent deviation between two opposing functional units. Conventional global overlay accuracy errors are error I and error II, which are formed by translation or rotation between the two substrates. This translation or rotation of the two substrates produces a corresponding translation or rotation error for all the respective opposing functional units on said substrates. Local overlay accuracy errors arise in relation to positioning, primarily due to elastic and / or plastic problems and / or due to initial processes (Vorprozesse), which in this case are mainly caused by continuously propagating bonding waves. Among the overlay accuracy errors shown, errors III and IV are primarily referred to as "run-out" errors. These errors are mainly due to distortion of at least one substrate during the bonding process. Due to the distortion of at least one substrate, the functional units of the first substrate are also distorted relative to the functional units of the second substrate. However, errors I and II can also arise due to the bonding process, but errors I and II are largely superimposed on errors III and IV, making them difficult to identify or measure. This applies to the latest types of bonders, especially fusion bonders, which have the potential for extremely precise x-correction and / or y-correction and / or rotational correction.

[0016] In the prior art, there already exists a device that can at least partially reduce local distortion. This is achieved through the use of active control elements for local correction (WO2012 / 083978A1).

[0017] In the prior art, there are initial solutions for correcting "runaway" errors. US20120077329A1 describes a method to achieve the desired alignment accuracy between functional units of two substrates during and after bonding by not fixing the lower substrate. Thus, the lower substrate is not subject to boundary conditions and can be freely bonded to the upper substrate during the bonding process. A key feature of this prior art is primarily the planar fixation of the substrates, largely achieved using vacuum equipment.

[0018] The resulting "runaway" error, in most cases, increases radially symmetrically around the contact area, thus increasing from the contact area outwards. In most situations, this involves a linear increase in the runaway error. However, under certain conditions, the runaway error can also increase non-linearly.

[0019] Under particularly optimal conditions, the "runaway" error cannot be determined solely by the corresponding measuring equipment (EP2463892), but can also be described by a mathematical function. Since the "runaway" error is a translation and / or rotation and / or scaling between well-defined points, it is preferably described by a vector function. Typically, this vector function is the function f:R 2 →R 2 Therefore, the mapping rule is as follows: this mapping rule maps the two-dimensional defined range of position coordinates to the two-dimensional value range of the "jumping" vector. Although a precise mathematical analysis of the corresponding vector field is not yet possible, assumptions are made regarding the functional properties. These vector functions are very likely to be at least C n The vector function (n>=1) is therefore differentiable at least once. Since the "jumping" error increases from the contact point towards the edge, the divergence of this vector function is likely not zero. The vector field is therefore very likely the source field.

[0020] It is best to determine the "runaway" error in relation to the structure. "Structure" is understood as any arbitrary element on the first or second substrate that is associated with a structure on the second or first substrate. A structure is thus, for example:

[0021] ● Alignment Marks

[0022] ●Corners or edges, especially the corners and edges of functional units.

[0023] ●Contact pads, especially through-silicon vias (TSVs) or through-polymer vias (TPVs).

[0024] ●Printed wires

[0025] ● Recesses (Vertiefung), especially holes or settlements (Senken).

[0026] "Jump" error is typically position-dependent and, mathematically, is a vector offset between a real point and an ideal point. Because "jitter" error is usually position-dependent, it is ideally described using a vector field. In the following text, unless otherwise stated, "jitter" error will be observed more as a point to facilitate description.

[0027] The "jumping" error R consists of two sub-components.

[0028] The first subcomponent R1 describes the intrinsic portion of the "runaway" error, that is, the portion attributable to the faulty fabrication of the structure or the distortion of the substrate. Therefore, the intrinsic portion of the "runaway" error is contained within the substrate. It should be noted that the substrate can also have an intrinsic "runaway" error when, although the structures have been correctly fabricated at a first temperature, the substrate is subjected to a temperature change to a second temperature until the bonding process, resulting in thermal expansion that distorts the entire substrate and consequently the structures located thereon. A temperature difference of a few Kelvin (sometimes even one-tenth of a Kelvin) is sufficient to produce such distortion.

[0029] The second subcomponent R2 describes the external portion of the "runaway" error, which is the portion caused by the bonding process. This external portion of the "runaway" error does not exist before the bonding process. The external portion of the "runaway" error primarily consists of localized and / or overall distortions of the first and / or second substrates caused by forces acting between the substrates, which may result in deformation in the nanometer range. Summary of the Invention

[0030] The objective of this invention is to provide a method for joining two substrates, thereby improving the joining accuracy at every possible location on the substrates. Furthermore, the objective of this invention is to elucidate a method by which error-free (especially full-surface) conformity of the structures of the two substrates can be achieved.

[0031] This task is accomplished using the features of claim 1. Advantageous improvements of the invention are described in the dependent claims. All combinations of at least two features described in the specification, claims, and / or drawings also fall within the scope of the invention. Values ​​within the stated range that fall within the mentioned boundaries should also be considered as boundary values, and these values ​​should be claimable in any combination. As long as a single method step or multiple method steps can be implemented on different devices or modules, these method steps are disclosed separately as independent methods.

[0032] The concept upon which this invention is based is that the heating temperature T has already been reduced during the bonding process. H Alternatively, the heating element can be disconnected during connection. Heating temperature T HIn particular, it is used to generate sufficient temperature for bonding at the bonding surfaces of the substrates. An important aspect of another embodiment of the invention is the release of the substrate from its fixation, especially during bonding, to allow for free deformation of the substrate stack being bonded. Another important aspect of a third embodiment of the invention is the possibility of ventilating the substrate stack, especially its interfaces, or applying pressure (Druckbeaufschlagung) to the substrate stack, especially its interfaces, during bonding.

[0033] As a first substrate and / or a second substrate, a wafer may be considered in particular.

[0034] The process of representing the characteristics of the bonding (especially durable bonding, preferably fusion bonding) according to the invention is to contact the two substrates as centrally as possible, in a point-like manner. In particular, the contact between the two substrates can also be achieved non-centrally. The bonding wave propagating from the non-central contact point will arrive at different locations on the edge of the substrate at different times. A complete mathematical and physical description of the bonding wave performance and the resulting “bouncing” error compensation can be correspondingly complex. In particular, the contact point is positioned not far from the center of the substrate, so that the possible effect is negligible at least at the edge. The distance between the center of the substrate and the possible non-central contact point is preferably less than 100 mm, preferably less than 10 mm, more preferably less than 1 mm, most preferably less than 0.1 mm, and most likely preferably less than 0.01 mm. In the following description, in general, “contact” should refer to a centrally located contact. More generally, “center” is preferably understood as the geometric center point of the ideal body on which the asymmetry is compensated when necessary. In notched wafers, a common feature in the industry, the center is the center point of a circle that surrounds an ideal wafer without a notch. In flat wafers, also common in the industry, the center is the center point of a circle surrounding an ideal wafer without a flat side. Similar considerations apply to substrates of arbitrary shapes. However, in certain embodiments, it may be useful to understand the "center" as the center of gravity of the substrate. To ensure precise, centered, point-like contact, an upper receiving device (sample holder) equipped with a centered bore and a pin that can translate within it is fitted with radially symmetrical fixing parts. It is also conceivable to use a nozzle, which instead of a pin, uses fluid (preferably gas) for pressure loading. Furthermore, when a device is provided that allows two substrates to approach each other via translational movement under the further premise that at least one of the two substrates (preferably the upper substrate) has an additional curvature toward the other substrate due to gravity, and thus automatically contacts each other during the aforementioned translational approach, provided that the distance from the respective second substrate is small enough.

[0035] The radially symmetrical fixing / holding parts are either vacuum holes, circular vacuum lips, or similar vacuum elements that can be used to secure the upper substrate. Electrostatic storage devices are also conceivable. A pin in a centrally drilled hole in the upper sample holder is used for controlled flexing of the secured upper substrate.

[0036] In another embodiment of the invention, the receiving device can be configured such that the first and / or second substrates are convex and / or concave due to overpressure and / or underpressure generated in the sample holder. For this purpose, a vacuum track and / or a fluid-flowable or ventable cavity is preferably provided in the receiving device. In particular, the use of nozzles for precise pressure loading can be eliminated, facilitating the overall pressure build-up. According to the invention, an embodiment is conceivable in which the substrate is sealed and / or otherwise secured (especially at the edges). If, for example, a receiving device is constructed to generate underpressure relative to the external atmosphere, sealing at the substrate edges is sufficient. If overpressure is generated inside the receiving device to cause the substrate to bend outward (i.e., convexly), the substrate is preferably secured (especially mechanically) at the edge side. The curvature of the substrate can be precisely adjusted by loading the substrate from below using underpressure or overpressure.

[0037] After the center contact of the two substrates is achieved, the fixing part of the upper sample holder (especially in a controlled and gradual manner) is detached. The upper substrate falls downwards partly due to gravity and partly due to the bonding force acting along the bonding wave and between the substrates. The upper substrate connects to the lower substrate radially from the center toward the side edges. This results in the construction of a radially symmetrical bonding wave according to the invention, which extends particularly from the center to the side edges. During the bonding process, the two substrates herdruecken the gas, especially air, between them before the bonding wave, thereby ensuring a bonding interface without gas inclusions. The upper substrate is effectively on an air cushion during descent.

[0038] After the bonding is initiated, the first / upper substrate is not subjected to additional fixation at the bonding initiation site; that is, apart from fixation at the bonding initiation site, the first / upper substrate is free to move and may also be distorted. Each kreissegment, infinitesimally small relative to its radial thickness, is distorted by the bonding wave advancing according to the invention, the stress state appearing at the bonding wavefront, and the current geometric boundary conditions. However, since the substrate is a rigid body, these distortions are summed as a function of the spacing viewed from the center. This results in "runaway" errors, which should be eliminated by the method and apparatus according to the invention.

[0039] Therefore, the present invention also relates to a method and an apparatus for reducing or even completely avoiding "jumping" errors between two bonded substrates during bonding (particularly through thermodynamic and / or mechanical compensation mechanisms). Furthermore, the present invention discusses corresponding articles (Artikel) manufactured using the apparatus and method according to the invention.

[0040] The "runaway" error is particularly related to its position along the substrate surface. This is especially evident in that the "runaway" error increases from the center of the substrate to its periphery. Such radially symmetrical runaway primarily occurs in the case of fused-bonded substrates that are centrally contacted by pins and whose bonding waves propagate autonomously (especially radially) after contact.

[0041] The "jumping" error is particularly related to the velocity of the bonding wave. Generally, the higher the bonding wave velocity, the greater the "jumping" error. According to the invention, it is therefore preferable to set the bonding wave velocity to be less than 100 mm / s, preferably less than 50 mm / s, even more preferably less than 10 mm / s, most preferably less than 1 mm / s, and most preferably less than 0.1 mm / s. In a particular embodiment of the invention, the bonding wave velocity is detected using a measuring device.

[0042] The "runaway" error is particularly related to the gap between the two substrates immediately before the start of the "pre" bonding process. The gap between these substrates is a function of positioning, as long as the deformation device deforms the first substrate, especially the upper one, with a first force F1. In particular, the gap between the substrates is largest at the edges. The minimum gap is located in the region of the maximum convexity of the deformed substrate. Therefore, the shape of the deformed substrate also affects the "runaway" error. Immediately before bonding, the gap between the substrates at the edges (substrate edge gap D) is set particularly 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, and most preferably less than 0.1 mm. Immediately before bonding, the gap between the substrates below the maximum convexity is set particularly to be less than 1 mm, preferably less than 100 μm, even more preferably less than 10 μm, most preferably less than 1 μm, and most preferably less than 100 nm.

[0043] "Jump" error is particularly related to the type and shape of the sample holder, and consequently to the fixation / holding of the corresponding substrate. Publication WO2014 / 191033A1 discloses several preferred embodiments of the sample holder, which are referred to in this regard. In the disclosed process, the separation of the substrate from the sample holder after release from fixation, especially vacuum fixation, is crucial. The surface roughness of the sample holder is chosen to be as large as possible, and the welligkeit of the sample holder is chosen to be as small as possible. Large surface roughness ensures as few contact points as possible between the sample holder surface and the substrate. The separation of the substrate from the sample holder is thus carried out with minimal energy expenditure. Welligkeit is preferably minimized so as not to create new sources of "jump" due to the sample holder surface. It should be noted that the statement regarding welligkeit does not imply that the surface of the sample holder is not allowed to be bent overall.

[0044] Roughness is described either as average roughness, square roughness, or average roughness depth. The measured values ​​of average roughness, square roughness, and average roughness depth are typically different for the same measurement segment or surface, but fall within the same order of magnitude. Therefore, the following numerical range of roughness should be understood either as the value of average roughness, the value of square roughness, or the value of average roughness depth. This roughness is set particularly to be greater than 10 nm, preferably greater than 100 nm, even more preferably greater than 1 μm, most preferably greater than 10 μm, and most preferably greater than 100 μm. "Jump" error is particularly time-related. Too-fast propagation of the bonding wave, shortly after and / or shortly on and / or shortly before the bonding wave, does not give the substrate material sufficient time to optimally interconnect. Therefore, it may also be crucial to control the bonding wave in a time-related manner.

[0045] "Runaway" error is particularly relevant to the loading process from the substrate to the sample holder. Distortions can occur during substrate application and fixation, which are maintained by fixation and introduced into the substrate stack during (pre)bonding. The substrate is thus transferred from the end effector to the sample holder with as little distortion as possible.

[0046] The "runaway" error is particularly related to the temperature difference and / or temperature fluctuation between the two substrates. These substrates are transported to the bonding module, particularly from different process steps or different process modules. In these process modules, different processes may have been performed at different temperatures. Furthermore, the upper and lower sample holders can have different structures, different construction methods, and thus different physical, especially thermal, properties. For example, it is conceivable that the thermal mass and / or thermal conductivity of the sample holders are different from each other. At the (pre)bonding time, this results in different loading temperatures or different temperatures. The sample holder for performing the process according to the invention is therefore preferably equipped with a heating and / or cooling system so as to enable precise adjustment of the temperature of at least one (preferably two) substrates. In particular, it is conceivable to adapt the temperatures of the two substrates to different values ​​so as to thermally distort the substrate as a whole by thermally loading at least one of the two substrates. Thus, the substrate is adapted to the desired initial state, especially to compensate for the "runaway" error component R1.

[0047] "Skip" error is particularly related to environmental stress. The effects of environmental stress have been discussed and published in detail in WO2014 / 191033A1. This document is provided for reference in this regard.

[0048] "Runaway" error is particularly related to the symmetry of the system, making it preferable that as many components as possible (more preferably at least the main components) be constructed and / or arranged symmetrically. In particular, the substrate thickness is different. Furthermore, different sequences of layers of different materials with different mechanical properties can exist on each substrate and should be considered. In addition, one substrate is preferably deformed, while the other substrate is placed flat on the sample holder. All characteristics, parameters, and implementations that lead to asymmetry have an impact on "runaway" error in particular. Some of these asymmetries cannot be avoided. Thus, the thickness of the substrate, the layers on the substrate, and the functional units are defined by process and customer specifications. According to the invention, attempts are made, in particular, to minimize "runaway" as much as possible, especially to completely eliminate "runaway," by changing other variable parameters.

[0049] The "jumping" error is particularly position-dependent. The objective of the measures according to the invention is to obtain, particularly at any position, a "jumping" error of less than 10 μm, preferably less than 1 μm, even more preferably less than 100 nm, most preferably less than 10 nm, and most preferably less than 1 nm.

[0050] Sample holder

[0051] The sample holder preferably used in embodiments of the invention has a fixing part. The fixing part is used to fix the substrate by a fixing force or by a corresponding fixing pressure. The fixing part can in particular be a fixing part that:

[0052] ●Mechanical fixing parts, especially clamps, or

[0053] ●Vacuum fixing parts, especially those with:

[0054] ○ Individually operable (ansteuerbar) vacuum rail, or

[0055] ○ Interconnected vacuum orbits, or

[0056] ● Electrical fixing parts, especially electrostatic fixing parts, or

[0057] ●Magnetic fixing part, or

[0058] ●Adhesive fixing parts, especially

[0059] ○Gel-Pak fixing part, or

[0060] ○ A fixing part with an adhesive, especially maneuverable, surface.

[0061] These fixation components are particularly operable electronically. Vacuum fixation is a preferred method. Vacuum fixation preferably comprises multiple vacuum tracks that are manifested on the surface of the sample holder. The vacuum tracks are preferably individually operable. In a technically preferred application, several vacuum tracks are combined into a vacuum track segment, which is individually operable, i.e., can be emptied or filled independently. Each vacuum segment is preferably independent of the other vacuum segments. This allows for the construction of individually operable vacuum segments. These vacuum segments are preferably constructed in a ring shape. This enables targeted, radially symmetrical (especially from the inside out) fixation and / or separation of the substrate from the sample holder, or vice versa.

[0062] Possible sample scaffolds have been disclosed in published documents WO2014 / 191033A1, WO2013 / 023708A1, WO2012 / 079597A1 and WO2012 / 083978A1. These publications are referenced in this regard.

[0063] Monitoring of the junction wave

[0064] During at least one (preferably all) of the process steps according to the invention, it is advantageous to detect and thus determine the advance of the engagement wave or at least the stated state of the engagement wave at a defined time point. For this purpose, a measuring device, particularly a measuring device equipped with a camera, is preferably provided. Monitoring is preferably carried out by means of:

[0065] ● Cameras, especially visual cameras or infrared cameras, and / or

[0066] ● Conductivity measuring equipment (Leitfaehigkeitsmessgeraeten).

[0067] If the position of the bonding wave is determined using a camera, the position of the bonding wave, especially its changing position, can be detected at any point in time. The camera is preferably an infrared camera that digitizes the data and transfers it to a computer. This computer then enables the analysis of this digital data, particularly the determination of the position of the bonding wave, the size of the bonded surface, or other parameters.

[0068] Another possibility for monitoring the advance of the bonding wave lies in measuring the surface conductivity, which changes with the advancing bonding wave. For this, preconditions for such a measurement must be given. Measurement of surface conductivity is performed, in particular, by contacting two electrodes at two opposing locations on the substrate. In a particular embodiment of the invention, the electrodes contact the edge of the substrate, wherein the electrodes do not obstruct bonding of the substrate at the edge. In a less preferred second embodiment of the invention, the electrodes are withdrawn from the surface before the bonding wave reaches the side edge of the substrate.

[0069] Several steps are then described, which are preferably performed in the described order, and in particular as separate steps. Unless otherwise described, these steps and the disclosure can be adapted from one embodiment to another (if this is technically feasible to a person skilled in the art).

[0070] Process according to the first embodiment of the invention

[0071] In the first step of a first embodiment of the method according to the invention, the positions of two substrates are determined and the two substrates are fixed on a sample holder, one substrate on a first / upper sample holder and the second substrate on a second / lower sample holder. The substrate transport can be performed manually, but is preferably performed automatically by a robot. The upper sample holder preferably has a deformation device for targeted, and particularly controllable, deformation of the upper first substrate using a first force F1. The upper sample holder particularly has at least one opening through which the deformation device (particularly a pin) can induce mechanical deformation of the upper first substrate. Such a sample holder is disclosed, for example, in publication WO2013 / 023708A1.

[0072] In the second step, the deformation device (especially the pin) contacts the back side of the upper first substrate and produces slight deformation, particularly a deflection from the side of the deformation device (i.e., from the top), referred to as the concave surface. The deformation device applies a first force F1 to the first substrate, specifically greater than 1 mN, preferably greater than 10 mN, even more preferably greater than 50 mN, most preferably greater than 100 mN, but particularly less than 5000 mN. If this force is too small, the upper first substrate will detach from the sample holder, but it is strong enough to produce the deflection according to the invention. This force preferably acts on the substrate in a point-like manner as much as possible. Since a point-like effect is practically nonexistent, the force preferably acts on a very small area, particularly less than 1 cm². 2 Preferably less than 0.1cm 2 More preferably less than 0.01cm 2 The most preferred size is less than 0.001 cm. 2 When applied to a concentration of 0.001cm... 2 In the case of an area, the effective pressure according to the invention is particularly greater than 1 MPa, preferably greater than 10 MPa, even more preferably greater than 50 MPa, most preferably greater than 100 MPa, and most preferably greater than 1000 MPa. The disclosed pressure range also applies to other areas disclosed above.

[0073] In the third step, the relative proximity of the two substrates is achieved, particularly through the relative proximity of the sample holders. Preferably, the lower sample holder is raised, causing the lower second substrate to actively approach the upper first substrate. However, it is also conceivable that the upper sample holder actively approaches the lower sample holder, or that the two sample holders approach each other simultaneously. The proximity of the two substrates is particularly achieved with a spacing between 1 μm and 2000 μm, preferably between 10 μm and 1000 μm, even more preferably between 20 μm and 500 μm, and most preferably between 40 μm and 200 μm. This spacing is defined as the minimum vertical distance between two surface points of the substrates.

[0074] Before bonding, pre-bonding, or contact, the first substrate and / or the second substrate are heated by a heating device and / or cooled by a cooling device, i.e., temperature-controlled.

[0075] In the fourth step, a further force is applied to the upper first substrate. According to the first mode of operation of the invention, the first substrate is subjected to a second force F2 from the deformation device, which is particularly greater than 100 mN, preferably greater than 500 mN, even more preferably greater than 1500 mN, most preferably greater than 2000 mN, and most preferably greater than 3000 mN. This creates or at least supports a first contact between the upper first substrate and the lower second substrate. The calculation of the preferably occurring pressure is recalculated by dividing this force by a minimum assumed value of 0.001 cm. 2 It is based on the area.

[0076] In the fifth step, the heating device is deactivated, especially the heating part of the lower sample holder, which is integrally arranged in the lower sample holder.

[0077] In the sixth step, the propagation of the advancing bonding wave is monitored in particular (see also "Monitoring of Bonding Wave" above). Monitoring specifically tracks the advance of the bonding wave and thus the progress of the bonding process during the following time periods: longer than 1 s, preferably longer than 2 s, even more preferably longer than 3 s, most preferably longer than 4 s, and most preferably longer than 5 s. The bonding process is not tracked / controlled during the time interval, but can also be described by the position of the bonding wave (especially radially). The tracking of the bonding process continues until the bonding wave is at a radial position corresponding to at least 0.1 times, preferably at least 0.2 times, even more preferably at least 0.3 times, most preferably at least 0.4 times, and most preferably 0.5 times the diameter of the substrate. If the tracking of the bonding progress is to be measured by conductivity measurements of the surface, the bonding progress can also be achieved by the percentage of bonded or unbonded surfaces. According to the invention, monitoring of the bonding progress is then, in particular, continued until the area is greater than 1%, preferably greater than 4%, even more preferably greater than 9%, most preferably greater than 16%, and most preferably greater than 25% has been bonded. Alternatively, monitoring is performed continuously.

[0078] The process flow control is preferably based on pre-defined / set or settable values ​​from monitoring, which fall within the value range mentioned above. This results in a first waiting time for the advance of the engagement wave until the start of the next process step.

[0079] In the seventh step, the fixing part of the upper first sample holder is disconnected in particular. It is also conceivable that the upper first substrate is detached by selectively releasing the fixing. In particular, in vacuum fixing parts comprising multiple individually operable vacuum tracks, the fixing is selectively released by continuously releasing the vacuum (especially from the center to the edge). The seventh step begins specifically at time point t1, at which time point t1, one of the parameters of the measuring device reaches a predetermined / set or settable value (see especially the sixth step).

[0080] More generally, or in other words, during engagement, the holding force F is reduced at time point t1. H1 In particular, it greatly reduces the holding force F H1 This causes the first substrate to detach from the first sample holder.

[0081] In the eighth step, the propagation of the advancing bonding wave is monitored, particularly by a measuring device, either re-monitoring or continuing. This monitoring preferably tracks the advancement of the bonding wave and thus the progress of the bonding process during a period greater than 5 seconds, preferably greater than 10 seconds, even more preferably greater than 50 seconds, most preferably greater than 75 seconds, and most preferably greater than 90 seconds. Instead of tracking the bonding process over time intervals, the tracking of the bonding wave can also be measured by the position of the bonding wave (especially radially). The tracking of the bonding process continues in particular until the bonding wave reaches a radial position corresponding to at least 0.3 times, preferably at least 0.4 times, even more preferably at least 0.5 times, most preferably 0.6 times, and most preferably 0.7 times the diameter of the substrate. If tracking the bonding progress is possible via conductivity measurements of the surface, the bonding progress can also be achieved by the percentage of bonded or unbonded surfaces. Here, according to the present invention, the bonding progress is continuously monitored until the area is greater than 9%, preferably greater than 16%, even more preferably greater than 25%, most preferably greater than 36%, and most preferably greater than 49%. Alternatively, monitoring is performed continuously.

[0082] The process flow control is preferably based on pre-defined / set or settable values ​​from monitoring, which fall within the value range mentioned above. This results in a second waiting time for the advance of the engagement wave until the start of the next process step.

[0083] In the ninth step, the deformation device is discontinued. If the deformation device is a pin, the pin is retracted. If the deformation device is one or more nozzles, the fluid flow is interrupted. If the deformation device is an electric field and / or magnetic field, the electric field and / or magnetic field is disconnected. The ninth step begins, in particular, at the point in time when one of the parameters of the measuring device reaches a predetermined / set or settable value (see, in particular, the eighth step).

[0084] In the tenth step, the propagation of the advancing bonding wave is monitored again or continued. This monitoring preferably tracks the advancement of the bonding wave and thus the progress of the bonding process during a period greater than 5 seconds, preferably greater than 10 seconds, even more preferably greater than 50 seconds, most preferably greater than 75 seconds, and most preferably greater than 90 seconds. Instead of tracking the bonding process over time intervals, the tracking of the bonding wave can also be described by the position of the bonding wave (especially radially). The tracking of the bonding process continues until the bonding wave is located at a radial position corresponding to at least 0.6 times, preferably at least 0.7 times, even more preferably at least 0.8 times, and most preferably 0.9 times the diameter of the substrate. If the substrate has an edge profile, it is impossible to track the bonding process down to the outermost edge because approximately 3-5 mm remains unbonded due to the edge profile. If tracking the bonding progress is possible via conductivity measurements of the surface, then the bonding progress can also be achieved by the percentage of bonded or unbonded surfaces. Here, according to the present invention, the bonding progress is continuously monitored until the area is greater than 36%, preferably greater than 49%, even more preferably greater than 64%, most preferably greater than 81%, and most preferably greater than 100% bonded. Alternatively, monitoring is performed continuously.

[0085] The process flow control is preferably based on pre-defined / set or settable values ​​from monitoring, which fall within the value range mentioned above. This results in a third waiting time for the advance of the engagement wave and until the start of the next process step.

[0086] An example of the process flow in the first implementation form will be reiterated below:

[0087] - Loading substrate

[0088] - Make the pin contact the chip (the force applied to the chip is 100mN), without initiating engagement.

[0089] - The two wafers are positioned close to each other (with a spacing of 40-200μm).

[0090] - Force is applied to the wafer to initiate a fusion bond between the two substrates (force of 1500-2800mN).

[0091] - Disable the heating unit

[0092] - Wait until the conjoined wave has traveled far enough (typically 1-5 seconds) - Waiting time 1

[0093] - (Especially when both regions are simultaneously) disconnect (deplete) the top wafer to maintain vacuum (Top Wafer Haltevakuum).

[0094] - Wait until the conjoined wave has traveled further (especially 2-15 seconds) - Waiting time 3 seconds

[0095] - Withdraw the sales order

[0096] - Wait until the conjugate wave has fully propagated (especially 5-90s) - Waiting time 4.

[0097] The steps and methods can be summarized by the general technical instruction described above.

[0098] The process according to the second embodiment of the invention

[0099] From the first to the seventh process step, including the seventh process step, the process steps according to the second embodiment correspond to the first embodiment.

[0100] In the eighth step, the holding force is reduced, or the fixing part of the lower second sample holder is disconnected. It is also conceivable that the lower second substrate is detached by selectively releasing the fixing part. Especially in the case of vacuum fixing parts comprising multiple individually operable vacuum tracks, selective release of the fixing parts is preferably achieved by continuously releasing the vacuum (especially from the center to the edge). The eighth step according to the invention is an important process for reducing "jumping" errors. By reducing the holding force or disconnecting the fixing part of the lower second sample holder, the lower / second substrate can be fitted to the upper first substrate according to the invention. By removing the fixing part, it appears that additional (mathematical-mechanical) boundary conditions that would restrict the bonding process are removed.

[0101] More generally, or in other words, during engagement, the holding force F is reduced at time point t2. H2 In particular, it greatly reduces the holding force F H2 This allows the second substrate to deform on the second sample holder.

[0102] The ninth process step corresponds to the eighth process step in the first implementation form.

[0103] In the tenth step according to the invention, the second substrate, which has already been partially bonded, is then fixed to the lower second sample holder. This tenth step is also an important process for reducing "runaway" errors. By re-fixing, and especially by re-energizing the vacuum, the continued development of the bonding is limited by (mathematical mechanics) boundary conditions.

[0104] More generally, or in other words, at time point t4 (especially after engagement), increase the holding force F. H2 .

[0105] The eleventh process step corresponds to the ninth process step according to the first embodiment, and the twelfth process step corresponds to the tenth process step according to the first embodiment.

[0106] In a very specific embodiment of the invention, the disconnection of the fixing part according to step 8 and the reconnection of the fixing part according to step 10 can be repeated multiple times before the bonding process ends. In particular, it is even possible to perform the disconnection and re-fixing in a position-resolved manner. This is mainly achieved by utilizing the individually operable vacuum track or vacuum section already mentioned in this disclosure. Ideally, this allows for position-resolved and / or time-resolved release or fixation of the lower / second substrate.

[0107] An example of the process flow for the second implementation will be reiterated below:

[0108] - Loading substrate

[0109] - Make the pin (deformation device) contact the wafer (especially with a force of 100mN acting on the wafer), but do not initiate engagement - Pin force 1

[0110] - Two wafers are positioned relatively close to each other (especially with a spacing of 40-200μm) - Spacing 1

[0111] - Pressed onto the wafer to initiate fusion bonding between the two substrates (especially with a force of 1500-2800mN) - Pin force 2

[0112] - Disable the heating unit

[0113] - Wait until the conjugate wave has traveled far enough (especially 1-5 seconds) - Waiting time 1

[0114] - (Especially when both regions are simultaneously) disconnect (deplete) the maintaining vacuum of the upper wafer.

[0115] - Disconnect (deplete) the vacuum maintaining the lower wafer.

[0116] - Wait until the conjoined wave has traveled further (especially 2-15 seconds) - Waiting time 3 seconds

[0117] - Maintain vacuum by connecting the lower chip - Vacuum 1

[0118] - Withdraw the sales order

[0119] - Wait until the conjugate wave has fully propagated (especially 5-90s) - Waiting time 4.

[0120] The steps involved can be summarized by the general technical instructions described above.

[0121] The process according to the third embodiment of the invention

[0122] From the first process step to the ninth process step, and including the ninth process step, the processes according to the third embodiment correspond to those in the second embodiment. In the ninth process step, the parameters are preferably set 10% to 40% lower than those in the second embodiment. This reduces the waiting time up to the tenth process step, wherein the third embodiment introduces additional waiting time or divides the second waiting time into parts.

[0123] In the tenth step according to the invention, ventilation is applied to the space between the lower second sample holder and the lower / second substrate, which is not actually fixed thereon, according to a defined pressure. "Pressure" here is to be understood as absolute pressure. An absolute pressure of 1 bar corresponds here to atmospheric pressure. To perform the process according to the invention, the chamber must therefore be emptied beforehand and subsequently opened to the atmosphere, i.e., ventilated. This facilitates the free movement of the substrate, thereby further minimizing distortion relative to the first substrate. This pressure is particularly between 1 mbar and 1000 mbar, preferably between 2.5 mbar and 800 mbar, more preferably between 5 mbar and 600 mbar, most preferably between 7.5 mbar and 400 mbar, and most preferably between 10 mbar and 200 mbar. In another embodiment according to the invention, it is conceivable that the process is carried out at atmospheric pressure up to the aforementioned tenth step, and then overpressure is generated in the chamber by a compressor. The pressure in this case is particularly between 1 bar and 3 bar, preferably between 1 bar and 2.5 bar, even more preferably between 1 bar and 2 bar, most preferably between 1 bar and 1.5 bar, and most preferably between 1 bar and 1.2 bar.

[0124] In the eleventh step, the propagation of the advancing bonding wave is monitored, particularly its re-emergence or continuation, using a measuring device. This monitoring tracks the advancement of the bonding wave and thus the progress of the bonding process during a period greater than 1 second, preferably greater than 2 seconds, even more preferably greater than 5 seconds, most preferably greater than 10 seconds, and most preferably greater than 15 seconds. Instead of tracking the bonding process over time intervals, the tracking of the bonding wave can also be indicated by the position of the bonding wave (especially radially). The bonding process is tracked until the bonding wave reaches a radial position corresponding to at least 0.3 times, preferably at least 0.4 times, even more preferably at least 0.5 times, most preferably 0.6 times, and most preferably 0.7 times the diameter of the substrate. If the tracking of bonding progress is measurable via conductivity measurements of the surface, then the bonding progress can also be measured as a percentage of the bonded or unbonded surfaces. According to the invention, monitoring of the bonding progress is carried out until the area is greater than 9%, preferably greater than 16%, even more preferably greater than 25%, most preferably greater than 36%, and most preferably greater than 49% has been bonded. Alternatively, monitoring is performed continuously.

[0125] The process flow control is preferably based on pre-defined / set or settable values ​​from monitoring, which fall within the value range mentioned above. This results in a first waiting time for the advance of the engagement wave until the start of the next process step.

[0126] In the twelfth process step according to the invention, the second substrate, which has been partially joined, is fixed to the lower second sample holder.

[0127] More generally, or in other words, increasing the holding force F at time point t4 (especially after engagement). H2 .

[0128] The thirteenth process step corresponds to the ninth process step in the first embodiment, while the fourteenth process step corresponds to the tenth process step in the first embodiment.

[0129] An example of the process flow for the third implementation will be reiterated below:

[0130] - Loading substrate

[0131] - Make the pin contact the wafer (especially with a force of 100mN applied to the wafer), without initiating engagement - pin force 1

[0132] - Two wafers are relatively close to each other (especially with a spacing of 40-200μm) - Spacing 1

[0133] - Pressed onto the wafer to initiate fusion bonding between the two substrates (especially with a force of 1500-2800mN) - Pin force 2

[0134] - Disable the heating unit

[0135] - Wait until the conjugate wave has traveled far enough (especially 1-5 seconds) - Waiting time 1

[0136] - (Especially when both regions are simultaneously) disconnect (deplete) the maintaining vacuum of the upper wafer.

[0137] - Disconnect (deplete) the maintaining vacuum of the lower wafer.

[0138] - Wait until the conjoined wave has traveled further (especially 1-10 seconds) - Waiting time 2 seconds

[0139] - Using a limited pressure (especially 10-200 mbar) - Pressure 1, ventilate the volume between the lower wafer and the chuck (lower sample holder) within a limited time period.

[0140] - Wait until the conjoined wave has traveled further (especially 2-15 seconds) - Waiting time 3 seconds

[0141] - Maintain vacuum by connecting the lower chip - Vacuum 1

[0142] - Withdraw the sales order

[0143] - Wait until the conjugate wave has fully propagated (especially 5-90s) - Waiting time 4.

[0144] The steps involved can be summarized by the general technical instructions described above.

[0145] Post-processing

[0146] The described process can be continued, especially in other process modules.

[0147] In the conceivable first continuation scheme (Weiterfuehrung), the resulting substrate stack (especially in the metrology module) is inspected. The inspection primarily involves measurements of the bonding interfaces to determine:

[0148] ● Alignment error, especially

[0149] ○ Overall alignment error, and / or

[0150] ○ Runout error, and / or

[0151] ●Defects, especially

[0152] ○ Pores, and / or

[0153] ○ Bubbles, and / or

[0154] ○ Crack.

[0155] If the inspection of the substrate stack has intolerable errors, the substrate stack is preferably separated again. Separation is preferably performed using the procedures and equipment disclosed in publications EP2697823B1 and WO2013 / 091714A1. Reference is made to these in this regard. Inspection of the bonding interfaces is performed, especially prior to further heat treatment.

[0156] In a conceivable second continuation, the resulting substrate stack is heat-treated. This heat treatment, in particular, leads to enhanced bonding between the substrates of the substrate stack. This heat treatment is performed, especially at temperatures above 25°C, preferably above 100°C, more preferably above 250°C, most preferably above 500°C, and most preferably above 750°C. This temperature substantially corresponds to the heating temperature T. H The resulting bond strength is especially greater than 1.0 J / m. 2 Preferably greater than 1.5 J / m 2 More preferably greater than 2.0 J / m 2 The most preferred value is greater than 2.5 J / m 2 The heat treatment is preferably carried out under a vacuum. The vacuum pressure is especially less than 1 bar, preferably less than 800 mbar, and even more preferably less than 10 mbar. -3 mbar, preferably less than 10 -5 mbar, preferably less than 10 mbar -8 mbar.

[0157] However, it is also conceivable to perform heat treatment in a protective gas atmosphere (Schutzgasatmosphaere). This is particularly advantageous when the protective gas facilitates heat transfer. The thermal conductivity of the protective gas is especially greater than 0 W / (m*K), preferably greater than 0.01 W / (m*K), even more preferably greater than 0.1 W / (m*K), and most preferably greater than 1 W / (m*K). The thermal conductivity of helium is, for example, between approximately 0.15 W / (m*K) and 0.16 W / (m*K). The protective gas, in particular:

[0158] ● Inert gases, especially helium, neon, argon, krypton, and / or xenon.

[0159] ● Molecular gases, especially carbon dioxide and / or nitrogen

[0160] ● Any combination of the gases mentioned above.

[0161] Preferably, the substrates have approximately the same diameters D1 and D2, wherein the diameters are particularly less than 5 mm apart from each other, preferably less than 3 mm, and even more preferably less than 1 mm.

[0162] According to another aspect of the invention, particularly independently, deformation is achieved by a mechanical actuation device (Stellmittel) and / or by temperature control of the first and / or second receiving devices.

[0163] By fixing the first substrate and / or the second substrate only in the region of the sidewall to the first receiving surface and / or the second receiving surface, the deformation according to the invention can be achieved more easily.

[0164] The results of the process according to the invention relate to multiple physical parameters that can be directly assigned to the substrate or the environment. Further in this disclosure, the most important parameters and their impact on "runaway" errors are described. These parameters are roughly divided into individual parameters and paired parameters. Individual parameters may not be assigned to a symmetry side, particularly not to the substrate. Paired parameters may have values ​​on a symmetry side, particularly the first substrate, that differ from those on the opposing symmetry sides, particularly the second substrate. There is an upper first symmetry side and a lower second symmetry side. Examples of individual parameters are the bonding wave velocity v or the gas (mixing) pressure p. Examples of paired parameters are substrate thicknesses d1 and d2.

[0165] If the effect of paired parameters on the bonding result is described in further steps, it is assumed, unless otherwise stated, that all other values ​​of each paired parameter are preferably equal. An exemplary example should be mentioned below. If the effect of two different substrate thicknesses d1 and d2 on the bonding result is described, it is assumed that the two E-modulos E1 and E2 of the two substrates are equal.

[0166] The aim is to minimize or completely eliminate the "runaway" error through an optimal, calculated, and / or empirically determined (especially time-dependent) bend line. The "runaway" line is here to be understood as a diagram of reduced symmetry of a one-dimensional function that maps the surface position of the substrate (i.e., the substrate surface) to a function of positioning coordinates, particularly radial coordinates. Reduced symmetry means that, based on the radial symmetry of the two substrates, the calculation of the one-dimensional bend line is sufficient to infer a two-dimensional contact between the substrates that produces the aforementioned minimal or completely eliminated "runaway" error. Simply put, the bend line of the substrate can be described, particularly towards the substrate surface toward the bonding interface. Preferably, the description of the bend line for the first substrate is similarly applicable to the second substrate.

[0167] The curvature (i.e. the substrate surface) is significantly affected by one or more of the following parameters according to the present invention.

[0168] The substrate thicknesses d1 and d2 are related to the volumes V1 and V2 and the densities ρ1 and ρ2 of the two substrates, and thus to the gravitational forces G1 and G2 of the two substrates. The gravitational force G1 of the first substrate has a direct influence on the acceleration performance of the upper first substrate in the direction of the lower second substrate. In the case of the lower fixed part being turned off, the gravitational force G2 is a measure of the inertial force of the lower second substrate, and thus a measure of whether the lower second substrate moves towards the upper first substrate along the bonding wave or remains against the upper first substrate.

[0169] E-modulosities E1 and E2 are measures of the stiffness of the substrate. These E-modulosities make a decisive contribution to the curvature and together define a function that describes how the substrates move toward each other.

[0170] Forces F1 and F2 affect the surfaces on which the two substrates are connected (especially centrally). Because point contact exists only in ideal conditions, it must always be assumed that the two substrates are in contact at the center of the surfaces. The size of the contact surfaces is determined by forces F1 and F2. The size of the contact surfaces is decisive for the boundary conditions.

[0171] The temperatures T1 and T2 of the two substrates can affect the overall thermal expansion state of the substrates. According to the invention, it can therefore be determined how strongly the substrates are distorted overall by thermal expansion with respect to a reference temperature. Proper temperature control of the upper and / or lower substrates is therefore an important aspect of achieving the most accurate and complete "runaway" compensation possible. Preferably, the temperatures of the two substrates can be set differently. These temperatures are specifically set such that the substrates are in an expanded state, in which the structures to be joined are aligned, i.e., the "runaway" error disappears (under the assumption that no additional "runaway" error is incorporated into the joining process due to the parameters already mentioned above). The required temperature for this purpose can be determined by measuring devices and / or empirically.

[0172] The gas (mixture) pressure p affects the atmospheric resistance to substrates moving towards each other. The gas (mixture) pressure can directly influence the bonding wave velocity v. For this information, refer to publication WO2014191033A1.

[0173] Before the actual joining process, the holding force F is maintained. H1 F H2 Primarily used for fixing the substrate. Holding force F H1These are the boundary conditions for process steps 1 to 6 (including process step 6), but they lose their influence on the boundary conditions determining the bending line after the fixing part is shut off. Similarly, the holding force F H2 It only participates as a boundary condition for the active lower fixed time point. For elasticity theory calculations, new boundary conditions must be expressed from process step 7 at the latest.

[0174] Initial radius of curvature r 10 r 20 These are the initial radii of the substrate prior to the process according to the invention. These initial radii of curvature are functions of positioning, but are in particular constant with respect to positioning. In a particular first embodiment according to the invention, the initial radius of curvature r of the lower second substrate... 10 Infinity, because the lower second substrate is laid flat at the start of the process according to the invention. In another particular second embodiment according to the invention, the initial radius of curvature r of the lower second substrate is... 10 It is a finite, positive, or negative constant, corresponding to a constant convex or concave curvature. In this case, the lower second substrate exists in a convex or concave curved shape at the start of the process according to the invention. Such a sample holder is described in publication WO2014191033A1, which is referred to in this regard. In particular, at least the initial radius of curvature r10 of the lower second substrate corresponds to the sample holder radius of curvature of the surface of the lower second sample holder on which the second substrate is placed.

[0175] The substrate curvature radii r1 and r2 along the junction wave are the results of solving the elastic theory equations considering the previously mentioned parameters. These substrate curvature radii are, in particular, functions of location and time.

[0176] The bonding wave velocity is a result of the parameters mentioned above. Attached Figure Description

[0177] Other advantages, features, and details of the invention will become apparent from the following description of preferred embodiments and from the accompanying drawings. In these drawings:

[0178] Figure 1a A schematic, non-to-scale cross-sectional view of a first step in a first embodiment of the method according to the invention is shown.

[0179] Figure 1b A schematic, non-scale cross-sectional view of the second process step is shown.

[0180] Figure 1c A schematic, non-scale cross-sectional view of the third process step is shown.

[0181] Figure 1d A schematic, non-scale cross-sectional view of the fourth process step is shown.

[0182] Figure 1e A schematic, non-scale cross-sectional view of the fifth process step is shown.

[0183] Figure 1f A schematic, non-scale cross-sectional view of the sixth process step is shown.

[0184] Figure 1g A schematic, non-scale cross-sectional view of the seventh process step is shown.

[0185] Figure 1h A schematic, non-scale cross-sectional view of the eighth process step is shown.

[0186] Figure 1i A schematic, non-scale cross-sectional view of the ninth process step is shown.

[0187] Figure 1j A schematic, non-scale cross-sectional view of the tenth process step is shown.

[0188] Figure 2 A schematic, non-to-scale cross-sectional view of an additional process step in a third embodiment of the method according to the invention is shown.

[0189] Figure 3 A schematic, non-scale cross-sectional view of optional additional process steps is shown, as well as

[0190] Figure 4 A schematic, non-scale cross-sectional view of two substrates is shown.

[0191] In these figures, the same components and components with the same function are represented by the same reference numerals. Detailed Implementation

[0192] Figure 1a The first process step is shown, in which the first, especially the upper, substrate 2 is fixed to the sample holder surface 1o of the first, especially the upper, sample holder 1. This fixing is achieved by a holding force F through a fixing device 3. H1 conduct.

[0193] The first sample holder 1 has a centrally located through-hole, specifically a drilled hole 4. This through-hole is used to pass through the deformation device 4 to deform the first substrate 2.

[0194] In the advantageous embodiment shown herein, the first sample holder 1 has holes 5 through which the engagement progress can be observed by a measuring device. The holes 5 are preferably longitudinally milled grooves.

[0195] The second substrate 2' is mounted and secured on the second, and particularly the lower, sample holder 1'. This securing is achieved by the holding force F through the fixing device 3'. H2 conduct.

[0196] The preferred fixing device 3, 3' is a vacuum fixing part.

[0197] Sample holders 1 and 1' particularly have a heating element 11 (heating device). In these figures, for clarity, the heating element 11 is schematically shown only in the lower second sample holder 1'.

[0198] All the parameters or forces mentioned that describe or affect the properties of substrates 2, 2' are generally functions of positioning and / or time.

[0199] The temperatures T1 and T2 of the two substrates 2 and 2' are referred to as instances of parameters. Typically, temperature T1 or T2 can be related to positioning, thus exhibiting a temperature gradient. In this case, it is meaningful to describe these temperatures as explicit functions of positioning and / or time.

[0200] The two gravitational forces G1 and G2 are referred to as instances of forces. These gravitational forces in these figures represent the total gravitational force acting on the substrates 2, 2'. However, it will be fully apparent to those skilled in the art that the two substrates 2, 2' can be decomposed into infinitesimally small parts (mass-produced parts) dm, and the effect of the gravitational force can be related to each of these mass-produced parts dm. Therefore, the gravitational force may generally be described as a function of position and / or time.

[0201] A similar concept applies to all other parameters and / or forces.

[0202] Figure 1b The second process step according to the invention is shown, wherein the deformation device 4 (in particular a pin) applies pressure to the back side 2i of the first substrate 2 to cause deformation of the first substrate 2. The deformation of the first substrate 2 is here performed using a first force F1.

[0203] According to Figure 1c In the process steps, two sample holders 1, 1' and thereby two substrates 2, 2' are brought close to each other until a defined distance is reached. The approach can also be performed during or before the second process step.

[0204] According to Figure 1d In the process steps, a second force F2 is used to initiate bonding, especially pre-bonding. The second force F2 ensures further, especially infinitesimal, deflection and brings the two substrates 2, 2' closer together, and finally into contact at the contact point 7.

[0205] The bonding wave (more precisely, the bonding wave front 8) propagates from the contact point 7 at a bonding wave velocity v, particularly radially symmetrically and preferably centrally. During other process steps, the bonding wave velocity v can be varied so that it can be defined as a function of positioning (or time). The bonding wave velocity v can be influenced by various measures.

[0206] According to Figure 1e In another process step, the heating section 11 of the first sample holder 1 and / or the second sample holder 1' is turned off, thereby interrupting further heating of the first substrate 2 and / or the second substrate 2'. According to... Figure 1f In another step of the process, the bonding wavefront 8 is monitored by means of a measuring device 9, particularly at least one optical system, preferably an infrared optical system. Through at least one aperture 5 (preferably corresponding to the number of optical systems), the measuring device 9 can detect the substrate back side 2i of the first substrate 2, and more preferably the bonding interface between the two substrates 2, 2', and thus detect the bonding wavefront 8. The detection of the bonding interface is particularly performed in the measuring device 9, which is sensitive to electromagnetic radiation that can penetrate the two substrates 2, 2' without significant weakening. Preferably, a light source 12 is positioned above and / or below and / or within the sample holder 1', the electromagnetic radiation of which illuminates and / or transmits through the substrates 2, 2' and / or the sample holder 1', and can be detected by the measuring device 9. The image thus captured is preferably a black and white image. The brightness difference allows for the clear identification of the bonded area from the unbonded area. The transition area between the two areas is the bonding wavefront. Such measurements can, in particular, determine the position of the junction wavefront 8, and thus, in particular for multiple such positions, the junction wave velocity v can also be determined.

[0207] Figure 1g Another seventh step is shown, in which the holding force F is reduced by at least... H1 The fixing part 3 of the first sample holder 1 is detached. If the fixing part 3 is a vacuum fixing part, it is even more preferable to have multiple individually controllable vacuum sections (with multiple holding forces F). H1 The vacuum fixing part is fixed by selectively disconnecting the vacuum section (or reducing one or more retaining forces F). H1 (especially the separation from the inside out).

[0208] Figure 1hAnother process step is shown, in which the bonding wavefront 8 is monitored by measuring device 9 after separation from the first substrate support 1.

[0209] Figure 1i Another process step is shown, in which the action of the deformation device 6 on the first substrate 2 is interrupted. If the deformation device 6 is a mechanical deformation device, especially a pin, interruption is achieved by retraction. In the case of a nozzle, interruption is achieved by disconnecting the fluid flow. In the case of an electric field and / or magnetic field, interruption is achieved by shutting off the field.

[0210] Figure 1j Another process step is shown, after which the two substrates 2, 2' are fully bonded to each other. In particular, in this process step, the bonding wavefront 8 (not shown here because bonding has ended in this process state) is further monitored by means of a measuring device 9 until bonding is completed, at which point the substrate stack 10 formed by the first substrate 2 and the second substrate 2' is completed.

[0211] Figure 2 Optional process steps are shown, particularly according to... Figure 1g After the process steps, reduce the holding force F of the lower second fixing part 3' and the lower second sample holder 1'. H2 In particular, the holding force F H2 The value is reduced to 0 even when the fixing part is deactivated. This in particular allows the second substrate 2' to move unimpeded, especially along the lower sample holder surface 1o' in the lateral direction.

[0212] In another advantageous embodiment, the second substrate 2' is raised along the bonding wavefront 8 to such an extent that the second substrate 2' is particularly locally raised from the lower second sample holder 2'. This is caused, in particular, by applying pressure to the second substrate 2' originating from the second sample holder 1'.

[0213] Gravity G2 resists the lifting of the second substrate 2' throughout the bonding process, and thus also affects the contact between the two substrates 2, 2' and thus affects the "jump".

[0214] Figure 3An optional process step according to the invention is shown, wherein the chamber in which the process according to the invention is performed is ventilated before the fully bonded substrate stack 10 is produced. This ventilation is particularly used to control the forward-advancing bonding wavefront 8. A precise description of the potential effects is disclosed in publication WO 2014 / 191033 A1, which is referred to in this regard. Ventilation is carried out using a gas or a mixture of gases. In particular, ventilation is carried out by opening a valve to the ambient atmosphere, so that the chamber is ventilated using the ambient gas (mixture). It is also conceivable to overpressure the chamber using a gas or a mixture of gases, rather than ventilating to the ambient atmosphere.

[0215] Figure 4 A schematic, non-to-scale illustration of two substrates 2, 2' is shown, defined by several parameters. The substrate surfaces 2o, 2o' correspond to the curvatures of the upper first substrate 2 and the lower second substrate 2' at defined points in time. They are definitively defined by the parameters already mentioned above. Their shapes change as a function of time during the bonding process according to the invention.

[0216] List of reference numerals

[0217] 1.1' Sample holder

[0218] 1o, 1o' Sample holder surface

[0219] 2, 2' Substrate

[0220] 2o, 2o' Substrate surface

[0221] 2i Substrate back side

[0222] 3, 3' Fixing Part

[0223] 4. Drilling

[0224] 5 holes

[0225] 6 Deformation device

[0226] 7 Contact Points

[0227] 8. Conjunction wavefront

[0228] 9. Measuring device

[0229] 10 Substrate Stack

[0230] 11 Heating section

[0231] 12 Light Sources

[0232] F1, F2 forces

[0233] F H1 FH2 Holding force

[0234] v Combined wave velocity

[0235] T H Heating temperature

[0236] Substrate temperatures T1 and T2

[0237] E1, E2 substrate E modulus

[0238] d1, d2 Substrate thickness

[0239] V1, V2 substrate volumes

[0240] substrate quality of m1 and m2

[0241] ρ1, ρ2 Substrate densities

[0242] Gravity of G1 and G2 substrates

[0243] substrate curvature radii r1 and r2

[0244] initial substrate curvature radii r10 and r20

[0245] D Substrate edge spacing

Claims

1. An apparatus for bonding a first substrate and a second substrate at corresponding contact surfaces of the substrates, the apparatus comprising: A first sample holder, the first sample holder being configured to utilize a first holding force (F) H1 The first substrate is held to the surface of the first sample holder by the first holding force (F). H1 A first vacuum is applied through the first sample holder; A second sample holder, the second sample holder being configured to utilize a second holding force (F) H2 The second substrate is held to the surface of the second sample holder by the second holding force (F). H2 A second vacuum is applied through the second sample holder; as well as A measuring device configured to detect a bonding wave between the first substrate and the second substrate during contact between the first substrate and the second substrate, and to reduce the first vacuum and the second vacuum to control the bonding wave between the first substrate and the second substrate, wherein the first vacuum and the second vacuum are reduced after waiting until the bonding wave has propagated sufficiently.

2. The device according to claim 1, wherein, The measuring device is further configured to detect the back side of the first substrate.

3. The device according to claim 1, wherein, The first holding force (F) H1 ) and the second holding force (F H2 At least one of them is reduced to 0 to control the bonding wave.

4. The device according to claim 1, wherein, The measuring device is further configured to detect the state of the junction wave and the propagation of the junction wave.

5. The device according to claim 1, wherein, The measuring device is further configured to detect the position of the bonding wave and the size of the bonded surface.

6. The device according to claim 1, wherein, The measuring device includes at least one of an optical system and a camera.

7. The device according to claim 1, wherein, The measuring device includes a conductivity measuring device.

8. The device according to claim 3, wherein, By applying vacuums to the first sample holder and the second sample holder respectively, the first sample holder and the second sample holder fix the first substrate and the second substrate to the first sample holder and the second sample holder respectively. The first holding force (F) is applied by vacuum force from the first sample holder and the second sample holder respectively. H1 ) and the second holding force (F H2 ), to fix the first substrate and the second substrate to the first sample holder and the second sample holder respectively, and The vacuum is reduced to reduce the first holding force (F). H1 ) and the second holding force (F H2 Furthermore, it controls the disconnection of the first substrate and the second substrate from the first sample holder and the second sample holder, respectively.

9. The device according to claim 1, wherein, The conjugate wave is detected over a period of time greater than 1 second.

10. The device according to claim 1, wherein, The measuring device is further configured to detect the bonding wave via the radial position of the bonding wave, the radial position of which corresponds to at least 0.1 times the respective diameters of the first substrate and the second substrate.

11. The device according to claim 1, wherein, The measuring device is further configured to detect the bonding wave by measuring the percentage of the bonded surfaces of the first substrate and the second substrate relative to the unbonded surfaces of the first substrate and the second substrate.

12. The device according to claim 1, wherein, The bonding wave is controlled taking into account the defined set of values ​​obtained through the measuring device.

13. The device according to claim 1, wherein, The engagement wave is controlled by selectively releasing the vacuum to disengage the fixing device.

14. A method for bonding a first substrate to a second substrate, comprising: Using the first holding force (F) H1 The first substrate is held to the surface of the first sample holder by the first holding force (F). H1 A first vacuum is applied by means of the first sample holder. Using the second holding force (F) H2 The second substrate is held to the surface of the second sample holder by the second holding force (F). H2 A second vacuum is applied through the second sample holder. During the contact between the first substrate and the second substrate, the bonding wave between the first substrate and the second substrate is measured; and The first vacuum and the second vacuum, respectively contained in the first sample holder and the second sample holder, are reduced to reduce the holding of the first substrate and the second substrate through the first sample holder and the second sample holder, respectively, thereby controlling the bonding wave, wherein the first vacuum and the second vacuum are reduced after waiting until the bonding wave has propagated sufficiently.

15. The method according to claim 14, wherein, The measurement of the junction wave further includes detecting the back side of the first substrate.

16. The method of claim 14, wherein, The first holding force (F) H1 ) and the second holding force (F H2 At least one of them is reduced to 0 to control the bonding wave.

17. The method of claim 14, wherein, The measurement of the junction wave further includes detecting at least one of the state of the junction wave and the propagation of the junction wave.

18. The method according to claim 14, wherein, The measurement of the bonding wave further includes detecting at least one of the position of the bonding wave and the size of the bonded surface.

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