Method for providing a displacement map, method for setting parameters for a bonding process, and composite substrate manufactured using such parameters, and apparatus for manufacturing a composite substrate - Patents.com

Abstract

A method for providing a displacement map (6) that can be better used for the qualitative evaluation of a performed bonding process, the method comprising the steps of: preparing a first substrate (1) and a second substrate (2); measuring the first substrate (1) to determine at least a first geometric parameter, in particular a macroscopic and / or microscopic first geometric parameter, and measuring the second substrate (2) to determine at least a second geometric parameter, in particular a macroscopic and / or microscopic second geometric parameter; bonding the first substrate (1) to the second substrate (2) to form a composite substrate (4); measuring the bonded composite substrate (4) to determine at least one measured third geometric parameter; and providing at least one simulated third geometric parameter for the bonded composite substrate (4) based on a composite model. The simulated third geometric parameter is simulated by the analysis device and / or simulation device (8) depending on the at least one first geometric parameter, the at least one second geometric parameter, and a preliminary displacement map (6'), which is generated by the analysis device and / or simulation device (8) and can be used in the composite model to compensate for deviations between the simulated third geometric parameter and the measured third geometric parameter.

Description

[Technical Field]

[0001] The present invention relates to a method for providing a displacement map, a method for setting parameters for a bonding process, a composite substrate manufactured using such parameters, and an apparatus for manufacturing a composite substrate. [Background technology]

[0002] In the prior art, several methods exist for bonding substrates, especially wafers, to one another. This bonding process is called bonding (bonden, bonding). Bonding can be divided into two main groups: permanent bonding and temporary bonding. In temporary bonding, two substrates are bonded together so that at least one of them can be processed. The second substrate acts as a carrier for mechanical stability. After processing, the first substrate, or product substrate, can either be transferred to a third substrate, cut with the carrier substrate, or removed from the carrier substrate. In all cases, the carrier substrate is removed in some way, and therefore the product substrate is only temporarily bonded. For this reason, precise alignment of the two substrates to one another is not critical. If the two substrates are aligned to within 0.5 millimeters of each other, this is usually sufficient from a process technology perspective.

[0003] In contrast, permanent bonding creates a permanent connection between two substrates. This permanent bonding is usually based on the so-called "direct bonding" (German: direct bonding). Direct bonding is a direct connection between two substrates via the surfaces of existing substrates without melting processes, phase transitions, or diffusion. Direct bonding is also frequently called "fusion bonds" (German: fusion bonds). The first important application of direct bonding is the joining of two oxidized substrates, one of which is prepared using the so-called SmartCut® technology. In the SmartCut® technology, ions, especially hydrogen atoms, are implanted into the substrate at a specific depth. The substrate surface is oxidized and bonded to a second substrate with an oxidized substrate surface. An additional heat treatment ensures that the prepared substrate is fractured along the implantation plane, allowing its upper part to be removed. The remaining substrate surface is still planarized and then lies on the buried oxide layer. Functional units, such as microchips, can then be fabricated on this remaining substrate surface. The present oxide layer prevents stray currents. This process has the advantage that after the two substrates are brought into contact (known as pre-bonding), the composite substrate can be exposed to any high temperature, since the substrates do not yet contain functional units that could be damaged by the temperature.

[0004] On the other hand, there are method steps in which a substrate already carrying functional units is bonded to a second substrate by direct bonding. In such cases, a lower temperature is required. Another problem, particularly with substrates that have already been processed and preferably provided with functional units, is the need to precisely align these substrates with the corresponding second substrate before direct bonding. This alignment is usually necessary because the functional units of one substrate need to communicate with the functional units of the second substrate. Communication is usually via copper wiring that extends from the functional units, usually through an oxide layer, to the substrate surface. When these copper wiring are formed in silicon or silicon oxide, they are called through-silicon vias (TSVs). There are countless such TSVs on the substrate surface. TSVs are the most important, but not the only, structures that need to be aligned with each other.

[0005] Another significant problem, which has become particularly evident in recent years, is the localized in-situ displacement between the surfaces of the substrates being bonded during bonding. In direct bonding, one substrate (preferably the lower substrate) is fixed to a substrate holder, while the second substrate initially makes point contact with the first substrate, particularly in the center. After this point contact, the second substrate is brought into contact with the first substrate in a controlled, sometimes uncontrolled, manner. This contact is achieved by the formation of a bond wave (Bondwelle, German, Bond wave, English) that propagates from the contact point to the periphery. During the propagation of the bond wave, partial regions of the substrate surfaces of both substrates may be displaced relative to each other. In particular, regions immediately in front of, along, or immediately behind the bond wave are subject to correspondingly large displacements. As a result, opposing structures on the two substrates that should actually be bonded to each other may no longer be in contact with each other or may only be in insufficient contact with each other.

[0006] Measuring and analyzing substrate surfaces has long been a well-known method for assessing the quality of different processes. However, this method is also used to evaluate substrate surfaces after coating, exposure, or etching processes. The ease of use is particularly due to the fact that the processed substrate surface is easily accessible to an optical system after the corresponding process. The most common application of this method is the measurement and analysis of structures formed by lithography processes in photographic coating. Idealized models of multiple structures exist in a computer. These structures are then transferred to photoresist by a lithography process. In particular, in the case of photolithography, structures on a photomask may not be optimally imaged in the photoresist due to diffraction phenomena or poor orientation of the template relative to the substrate. By comparing the structures actually formed in the photoresist with the ideal structures in the computer, a displacement map can be generated. This displacement map is constructed as a collection of displacement vectors at as many positions as possible. Each displacement vector indicates how much the actual structure position differs from the ideal structure position. By calculating the change in the displacement vector as a function of position, a corresponding distortion map can further be calculated.

[0007] One problem with the prior art is that the displacement map between the substrate surfaces of two bonded substrates is not always directly accessible. After the bonding process, a transmission method must be used to inspect the bonded substrate surfaces. For example, infrared light and a suitable infrared camera can be used to transmit-illuminate the two bonded silicon wafers.

[0008] However, in most cases, the substrate to be transilluminated, which is usually a silicon substrate, is coated with some layer, in particular a metal layer, or already has functional units that also have metal parts, and since metal is not transparent to infrared light, measuring the interface is difficult or even impossible.

[0009] However, the problem in the prior art remains the need to bond substrates together in a controllable manner across their entire surfaces, with minimal, and especially no, displacement of the aligned structures relative to each other at each position. Therefore, all structures on a first substrate must be in contact with and bonded to their corresponding structures on a second substrate with minimal error. The problem lies not only in the fact that, because the structures are already displaced from their ideal positions during fabrication, in the worst case scenario, each substrate has a displacement map describing the deviation of the structures from their ideal positions, but also in the fact that these displacement maps may change during bonding, particularly due to mechanical properties before, during, and after the bonding wave. The change in the displacement of the structures during the bonding process is particularly problematic for structure sizes in the micrometer and nanometer range.

[0010] The prior art does not solve, or at least does not solve satisfactorily, the problem of determining a displacement map between two substrate surfaces of a composite substrate bonded together. Summary of the Invention [Problem to be solved by the invention]

[0011] It is therefore an object of the present invention to provide a quantitative assessment for a bonding process, which can be used independently of the material composition of the substrates bonded together, and preferably does not require additional measurement steps to optimize parameters for the bonding process based on the quantitative assessment. [Means for solving the problem]

[0012] The present invention solves the above problem by a method according to claim 1, a method according to claim 12, a composite substrate according to claim 13, and an apparatus according to claim 14. Further advantageous embodiments can be found from the dependent claims, the drawings and the following description.

[0013] According to a first aspect, there is provided a method for providing a displacement map suitable for use for the qualitative evaluation of a performed bonding process, comprising the steps of: providing a first substrate and a second substrate; - measuring the first substrate to determine at least one first geometric parameter, in particular a first macroscopic and / or microscopic geometric parameter, and measuring the second substrate to determine at least one second geometric parameter, in particular a second macroscopic and / or microscopic geometric parameter; bonding the first substrate to the second substrate to form a composite substrate; measuring the bonded composite substrate to determine at least one measured third geometric parameter; providing at least one simulated third geometric parameter for the bonded composite substrates based on a composite model, the simulated third geometric parameter being simulated by an analysis device and / or simulation device based on the composite model depending on the at least one first geometric parameter, the at least one second geometric parameter and a preliminary displacement map indicating local deviations from a desired ideal position, the preliminary displacement map being generated by the analysis device and / or simulation device and preferably adapted in the composite model, in particular to compensate for deviations between the simulated third geometric parameter and the measured third geometric parameter; comparing the at least one simulated third geometric parameter with the at least one measured third geometric parameter; providing the preliminary displacement map as a displacement map, the preliminary displacement map having a minimum deviation between the simulated third geometric parameter and the at least one measured third geometric parameter.

[0014] In contrast to the prior art, the displacement map is determined by a simulation that predicts the appearance and shape of the composite substrate, the simulation first taking into account geometric preconditions of the first and second substrates, i.e., at least one first geometric parameter and at least one second geometric parameter.

[0015] The displacement map reflects the local deviation between the intended relative position of the first substrate with respect to the second substrate and the actual relative positions of the first and second substrates, particularly with respect to their respective substrate surfaces. The displacement map thus indicates the extent to which local portions of the first and second substrates are laterally offset or displaced from their ideal positions during bonding and therefore misaligned with each other. The displacement map can be thought of as a two-dimensional vector array that assigns a magnitude and direction to each subsection between the first and second substrates relative to the lateral offset present in each case. When the offset is zero, the first and second substrates ideally overlap each other at this subsection, or multiple subsections to be bonded are essentially aligned with each other. It has been found that the lateral or lateral displacement of the subsections that occurs locally during bonding affects the geometry, i.e., the outline, of the composite substrate. It has further surprisingly been found that a displacement map can be determined using simulation by comparing a predicted geometry of the composite structure with the actual geometry using a composite model, and adjusting the preliminary displacement map, taking into account the geometries of the first and second substrates, until the predicted geometry essentially matches the actual geometry. This allows for the determination of a displacement map at the interface between bonded composite substrates, particularly the first and second substrates, without the use of transmission methods.

[0016] Preferably, the preliminary displacement map is adjusted at least once to find a preliminary displacement map having a minimum deviation between the simulated third geometric parameter and the at least one measured third geometric parameter.

[0017] For an unstructured first or second substrate, imagine an ideal, perfect, highly symmetrical grid with evenly spaced grid lines on the surfaces of the substrates being bonded. The grid lines represent the mechanically undistorted state of the substrate surfaces. During the bonding process between two unstructured substrates, displacements of individual parts also occur before, during, and after the bonding wave. These displacements are caused by the mechanical forces exerted by the traveling bonding wave on its surroundings. As an example, imagine a situation in which the second substrate is held perfectly flat by the lower substrate holder. In this case, no part of the substrate can be displaced by displacement, bending, or rotation. However, the first substrate placed on the second substrate can be compressed, stretched, rotated, or bent as the bonding wave travels. Although these elastic displacements are very small, they are fixed after the bonding wave has passed by the direct bond that occurs behind the bonding wave. Now, if we imagine the grids initially defined on both substrate surfaces, we can see that at least one grid, particularly that of the first substrate, is no longer ideal, perfect, or highly symmetrical: its grid lines have been displaced. And as the displacement varies with position, a corresponding distortion also occurs.

[0018] Similar considerations apply to structured substrates, e.g., with functional units or TSVs. Simply put, it is added that one no longer has to imagine a grid, but can immediately identify the structures that must be specifically matched.

[0019] The method is preferably applied to structured first and second substrates and / or unstructured first and second substrates. It is particularly advantageous to use unstructured substrates to build an initial approximation model. Unstructured first and second substrates are inexpensive, in contrast to already processed first and second substrates. By performing multiple test runs using unstructured first or second substrates, a composite model can be calculated that can estimate the effects of at least environmental temperature, ambient pressure, substrate thickness, substrate curvature, and locally varying substrate curvature. In particular, these models can be used as initial models for relatively expensive patterned substrates. The patterned first and second substrates, respectively, can then be used to refine the composite model.

[0020] The at least one first geometric parameter and / or the at least one second geometric parameter and / or the third geometric parameter preferably comprise a thickness as a function of position, a local curvature as a function of position, and / or a global curvature of the first substrate, the second substrate, and / or the composite substrate. A geometric parameter may also be understood to mean a local displacement of the substrate surface that is externally accessible and measurable by a detector. Such a displacement may relate to a displacement at the bonding interface that is not externally accessible by a detector. It is also possible to measure the surface roughness of the bonded substrate surfaces as a function of position. In particular, surface roughness may affect the propagation of the coupled wave. Preferably, the thickness as a function of position, the local curvature as a function of position, and the global curvature of the composite substrate are determined. More preferably, only externally accessible properties of the composite substrate, i.e., the local and global curvatures as a function of position and the thickness of the composite substrate, are measured. Measuring the composite substrate is also referred to as measuring the outer shell of the composite substrate. In the remainder of the text, this preferably refers to the measurement of all externally accessible measurement variables of the composite substrate that contribute to the composite substrate's geometry. Therefore, more preferably, the bonding interface between the two substrates does not need to be examined by transmission methods. This proves to be particularly advantageous for substrates that are at least partially opaque to electromagnetic radiation. For example, many substrates have metal layers or metallic functional units, which strongly absorb infrared radiation, making infrared transmission observation impossible. However, it is generally assumed that undesirable displacements of the substrate surfaces relative to each other occur during the initial bonding process. In particular, in the case of substrates with structures, the structures on both substrates are not yet in optimal contact with each other, i.e., there is a displacement between the structures of the first substrate and the structures of the second substrate. Therefore, the present invention allows for the adjustment of displacements that could not previously be quantified using conventional techniques.

[0021] The geometrical parameters are preferably measured by imaging on the substrate and / or by interferometry and interferometry devices. Preferably, an apparatus is used that records an interference pattern across the surface of the substrate, from which spatially resolved displacement and / or curvature of the substrate or substrate stack can be deduced.

[0022] The resolution of the camera that records the full real-world image or the interferometric image also determines the accuracy of the method: the higher the resolution of the camera, the more accurate the method according to the invention can be.

[0023] The geometric parameters are preferably measured by analyzing images from a digital camera, in particular one equipped with a CMOS or CCD sensor. To be able to measure the geometric parameters, the highest possible resolution or pixel density is required. The more pixels there are per unit area, the more accurately the geometric parameters can be measured. To determine how many pixels there are in a spatial dimension, it is best to specify the number of pixels per unit line. Advantageously, the number of pixels per wafer diameter is specified. The number of pixels per wafer diameter is greater than 1,000, preferably greater than 10,000, more preferably greater than 25,000, most preferably greater than 35,000, and most preferably greater than 50,000. The resolution of the camera in megapixels (MP) is greater than 1 MP, preferably greater than 100 MP, more preferably greater than 625 MP, most preferably greater than 1,225 MP, and most preferably greater than 2,500 MP. The measurement of the geometric parameters on the substrate surface is preferably carried out by acquiring an interference image. In particular, due to blanket illumination of a typically curved and / or distorted substrate surface, phase differences arise due to different path lengths, producing an interferometric image from which the curvature and / or distortion can then be estimated.

[0024] During bonding, the first and second substrates are preferably aligned. This is achieved using a dedicated alignment device. Alignment markers are preferably arranged on the periphery of the substrates. When unstructured substrates are bonded together, precise alignment can be omitted, especially if there are no alignment markers on the substrates. In this case, the substrates are aligned to each other only mechanically. However, to prevent the influence of inaccurate, purely mechanical alignment from becoming part of the subsequently calculated model, it is conceivable to apply simple alignment markers to the unstructured substrates.

[0025] In the composite model, a two-dimensional displacement map is preferably inserted between the substrate surfaces of the simulated substrates to be bonded together. This displacement map models the physical effects of a traveling bond wave. The displacement map mathematically describes how the structure of a first substrate is displaced relative to the structure of a second substrate when initial and boundary conditions are specified. For unstructured substrates, a virtual grid is used. Ideally, the displacement map is described by a vector analytic function, but in the simplest case, it can simply be a set of pairs of tuples. The first element of the pair tuple represents the position of the interface, and the second element of the pair tuple is the displacement vector. Therefore, the displacement map can also be presented in tabular form. The first column, particularly the left column, gives the position at the interface, and the second column gives the displacement vector. Thus, the displacement map can be used to represent, at a local field resolution, how the structure on the substrate surface of the first substrate is displaced from the structure on the substrate surface of the second substrate.

[0026] The absolute value of the displacement vector is 0 nm to 100 μm, preferably 0 nm to 10 μm, more preferably 0 nm to 1 μm, most preferably 0 nm to 100 nm, and most preferably 0 nm to 10 nm.

[0027] Preferably, the composite model is generated by an analytical device and / or a simulation device, e.g., a computer, and can be used to simulate the bonded substrate stack. Preferably, the terms analytical device and / or simulation device can refer to a (personal) computer, a virtual machine running on host hardware, a microcontroller, or an integrated circuit. Alternatively, the analytical device and / or simulation device can be a physical or virtual computer group (the technical term for a physical computer group is a "cluster," and the technical term for a virtual computer group is a "cloud"). Preferably, the analytical device comprises a computing unit and a memory unit. The computing unit can include hardware and software elements, e.g., a microprocessor or a field programmable gate array. The memory unit or storage device can be implemented as a non-persistent working memory (e.g., random access memory) or as a persistent mass storage device (e.g., hard disk, USB stick, SD card, solid state disk). Furthermore, it is conceivable that the analytical device comprises at least one server, and that at least one platform or network of multiple servers supporting each other in carrying out the method is used.

[0028] A substrate stack comprises at least two substrates. It is also conceivable to use substrate stacks with more than two substrates (multi-stacks). More preferably, the measured geometric parameters of the first and second substrates are used to generate a simulated composite substrate in an analysis device and / or simulation device before bonding. Furthermore, a displacement map can be generated by the analysis device and / or simulation device, and this displacement map can be used to calculate a simulated third geometric parameter. After the calculation of the simulated third geometric parameter is completed, the simulated third geometric parameter can be compared with the measured third geometric parameter. For example, the third geometric parameter can be the overall outline or geometric shape of the composite substrate. If both geometric shapes or geometric parameters are the same, it can be assumed that the preliminary displacement map corresponds to the actual displacement map. Next, this method step will be described in more detail.

[0029] More preferably, a composite model is determined and provided in a preparatory method step. One challenge is to determine the composite model on the one hand and to find an accurate displacement map on the other hand. This is possible by bonding and measuring multiple composite substrates. In the preparatory method step, the composite model is approximated by multiple bonding processes and measurement variables, particularly geometric parameters, measured during the bonding processes. Once the composite model is established in the preparatory method step, more preferably, changes in the preliminary displacement map are realized in an analysis and simulation device until the simulated third geometric parameter matches the measured third geometric parameter. The determination of the composite model in the preparatory method step is described below.

[0030] In actual bonding, environmental parameters such as temperature, ambient pressure, and atmosphere are presumed to be responsible for the actual displacement map. Therefore, in the model, it is sufficient to vary only the displacement map until the contour of the bonded simulated substrate stack matches the contour of the measured substrate stack. Once this displacement map is obtained, all environmental parameters can be automatically associated with it. Therefore, the model preferably correlates only the displacement map with the contour of the simulated composite substrate, or more simply, with the simulated composite substrate.

[0031] In the first method, the calculation of the model from the simulated displacement map is preferably carried out using the finite element method (FEM) or the finite difference method (FDM). Given known initial and boundary conditions of the individual substrates and a given displacement map, this is simply a problem of elasticity theory. The finite element method is simply used to calculate how the substrate stack will deform given the displacement map. However, the FEM and FDM methods are relatively time consuming.

[0032] In the second method, the calculation of the model is performed using a set of mathematical basis functions (Basisfunktionen, German: mathematical basis functions, English: ). A preferably linear superposition of the basis functions allows the calculation of a simulated bonded substrate stack for a given displacement map. The basis functions have model parameters that can be determined using appropriate methods, from which the basis functions themselves are constructed.

[0033] In the third method, the calculation of the model is carried out by artificial intelligence, in particular by neural networks. The basis functions or FEM model has self-adaptive model parameters that are determined by the collected data set, preferably by a minimization task, and once these model parameters are determined, a model is available that can be used to calculate a displacement map from the fitted parameters or to calculate fitted parameters from the displacement map.

[0034] During optimization, it is possible to use a single local displacement as the fitting parameter, or to reduce the number of variables by using models for local displacement (four-parameter model, six-parameter model, HOWA, Zernike polynomials, Legendre polynomials, etc.). When using models, more or less residual error will remain depending on the complexity of the model.

[0035] When creating a model, the following simplifications can be made: Preferably, the calculation of the model parameters takes advantage of the symmetry of the system. For example, it is conceivable to ignore the orthotropy that is usually present and make the system axisymmetric with respect to its mechanical properties, greatly simplifying the calculations. Basis functions or FEM models are used to calculate only a small part of the surface. The calculation of the remaining part is carried out by applying the symmetry.

[0036] It is also conceivable to ignore the initial shape and thickness of the individual substrates and simply use standard thicknesses according to the so-called SEMI standards. The following additional information allows for the construction of a more detailed and complex composite model.

[0037] - using all available information from the initial substrate, i.e. backside / frontside topography combined with the measured local thickness, and / or - Using known information about multiple layers on a substrate (e.g., metal layers, oxide layers under stress, etc.).

[0038] Preferably, it is intended that the comparison is repeated iteratively for different preliminary displacement maps until a displacement map is determined, which allows the displacement map to be determined by a relatively simple algorithm.

[0039] More preferably, a displacement map is determined for a first set of parameters describing a first bonding process and an additional displacement map is determined for a second set of parameters describing a second bonding process, further comprising the steps of: - comparing said displacement map with said additional displacement map; - establishing a third set of parameters to be used for a third bonding process, the third set of parameters being dependent on a comparison between the displacement map and the further displacement map. Preferably, therefore, a plurality of displacement maps can be used to compare a plurality of different bonding processes and their likelihood of success.

[0040] The first set of parameters and / or the second set of parameters and / or the third set of parameters comprises at least one parameter, more preferably the globally statistically averaged environmental temperature. Preferably, a temperature map of at least one substrate, preferably both substrates, is also recorded over time and is understood to be a parameter indicative of how the temperature in the vicinity of the bond wave front behaves thermally as the bond wave progresses, as well as how the temperatures of the upstream and downstream surface regions behave thermally.

[0041] In a further refinement, the overall statistically averaged ambient pressure is measured and assigned to the set of parameters. In a further refinement, the bonding apparatus has multiple flow sensors arranged radially symmetrically, preferably at equal angular intervals. The flow sensors are positioned in the plane through which the bonding interface passes. These sensors indicate the contact point where bonding begins, particularly the center of the two substrates. The purpose of the flow sensors is to measure the air flow generated as the bonding wave advances. The bonding wave pushes the air present between the first and second substrates outward radially symmetrically. The air cushion thus created between the first and second substrates affects how quickly the first substrate bonds to the second substrate. Therefore, for example, by changing the gas composition, it is possible to influence the bonding behavior. Adding very light elements such as helium can influence the gas dynamics and thus the associated mechanical behavior of the first and second substrates, particularly the descending first substrate. Therefore, the measurements of these flow sensors are also preferably included in the set of parameters.

[0042] In a further refinement, the atmospheric composition is measured and used as part of the set of parameters. Of particular importance is the measurement of air humidity, i.e., the water content in the atmosphere. Experience has shown that humidity has a significant impact on the bonding result. Water can condense on the substrate surface, thereby contributing to improved bonding quality, especially when the substrate surface is hydrophilic.

[0043] In a further refinement, the settings of the deformation means for deforming at least one substrate are recorded during deformation. If the deformation means is a pin, the position of the pin, its velocity and the force acting on the substrate are preferably measured over time. The position is preferably determined directly by the number of steps of a stepper motor, preferably by other measuring means. The velocity and acceleration are automatically determined as first and second derivatives of the distance-time relationship. The force is preferably measured by a load cell. The load cell is either integrated into the pin or arranged to the side or behind the pin. In these two cases, easy replacement is ensured. If the deformation means is a nozzle, the flow rate, pressure and volumetric flow rate of the outflowing gas are preferably measured.

[0044] It is preferably provided that the temporal variation of at least one parameter during the bonding process is determined by at least one measuring device, in this way advantageously making it possible to take into account that at least certain parameters may vary during the bonding process.

[0045] In particular, it is provided that the thickness of the first substrate and / or the second substrate has a value of 100 nm to 5000 μm, preferably 100 nm to 800 μm, and most preferably 100 nm to 500 μm. The substrates to be bonded are therefore relatively thin substrate layers. The substrates may be of any shape, but are more preferably circular. The diameter of the substrate is particularly standardized industrially. For wafers, the standard industrial diameters are 1 inch (2.54 cm), 2 inches (5.08 cm), 3 inches (7.62 cm), 4 inches (10.16 cm), 5 inches (12.7 cm), 6 inches (15.24 cm), 8 inches (20.32 cm), 12 inches (30.48 cm), and 18 inches (45.72 cm).

[0046] Preferably, multiple sub-segments of the displacement map are simulated, for example understood as multiple portions within the grid of the displacement map or multiple small portions of the displacement map, in this way, for example, the importance or relevance of individual sub-segments can be increased.

[0047] Preferably, machine learning is intended to be used to determine at least one parameter for the composite model and / or the third set of parameters. In particular, it is envisaged that the determined displacement map may be saved together with the parameters of the bonding process and used as training data for optimizing the parameter settings in the composite model or the bonding process. Preferably, the training data may be shared globally, for example via a cloud, to assist analysis devices and / or simulation devices in finding the optimal composite model or optimal bonding parameters.

[0048] Another subject of the invention is a method for setting parameters for a bonding process, in which a displacement map is provided for setting the parameters and on the basis of which the parameters for the bonding process are determined, the displacement map being provided by the method according to the invention. All advantages and properties described for the method for providing a displacement map apply equally to the method for setting the parameters and vice versa.

[0049] Another subject of the invention is a composite substrate manufactured from a first substrate and a second substrate in a bonding process using the parameters set according to the method according to the invention. All advantages and properties described for the method for setting the parameters apply equally to the composite substrate and vice versa.

[0050] Another subject of the invention is an apparatus for measuring and / or bonding a first substrate, a second substrate, respectively, as a composite substrate, and a composite substrate, the apparatus comprising: The apparatus comprises at least one analysis and / or simulation device suitable and adapted to perform the method according to any one of the preceding claims. All advantages and properties described with respect to the method for providing a displacement map apply equally to the device and vice versa. More preferably, the device is intended to comprise means for bonding. For example, a bonding device is configured to perform the bonding method according to the invention.

[0051] Most preferably, it is intended that the apparatus comprises at least one measuring device, preferably adapted to determine a parameter in the joining process and / or the first, second and / or third geometric parameter.

[0052] The method according to the invention can be applied immediately after bonding. However, it is also conceivable that the method is applied only after mechanical and / or chemical treatment of the bonded substrate stack, in particular after a re-thinning treatment. The treatment of the substrate stack changes geometric parameters such as thickness and / or curvature. It is assumed that the displacement map at the bond interface is not affected by such subsequent treatment of the substrate stack.

[0053] Further advantages, features and details of the present invention will become apparent from the following description of preferred embodiments and the drawings. [Brief explanation of the drawings]

[0054] [Figure 1] FIG. 1 illustrates a process flow of a method according to a preferred embodiment of the present invention. [Figure 2] 2 is a schematic diagram of some method steps of the method of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0055] In the drawings, identical components or components having identical functions are provided with the same reference numerals. 1 shows a process flow of a method according to a first preferred embodiment of the present invention. In a first method step 10, a first substrate 1 and a second substrate 2 are selected. In a second method step 20, the first substrate 1 and the second substrate 2 are measured, in particular to determine at least one first geometric parameter of the first substrate 1 and to determine at least one second geometric parameter of the second substrate 2. In an optional third method step 30, the first substrate 1 and the second substrate 2 are aligned with each other, preferably in an alignment device that holds and positions the first substrate 1 with a first holder and the second substrate 2 with a second holder. In a fourth method step 40, the first substrate 1 and the second substrate 2 are bonded, i.e., joined, to each other. In a fifth method step 50, the bonded composite substrate, i.e., the composite substrate, is measured to determine a measured third geometric parameter. In a sixth method step 60, a composite model is generated in the analysis and / or simulation device, which includes the displacement map or is based on the use of the displacement map. The analysis and / or simulation device includes at least one microprocessor, e.g., a computer. It is also conceivable that the analysis and / or simulation device is part of a network and / or is cloud-based.

[0056] In a seventh method step 70, a simulated third geometric parameter for the simulated composite substrate is determined or calculated using the first and second geometric parameters determined in the second method step 20 and the simulated displacement map from the sixth method step 60. In an eighth method step 80, the at least one measured third geometric parameter is compared with the at least one simulated third geometric parameter to determine the extent to which the simulated composite substrate matches or is displaced from the actual, i.e., bonded and measured, composite substrate. If the simulated composite substrate matches the actual composite substrate, particularly with respect to the simulated and measured third geometric parameters, the displacement map simulated by the analysis device and / or simulation device is identical to the actual displacement map, and the method ends in a ninth method step 90. The simulated displacement map is the final displacement map provided by the method.

[0057] If the simulated composite substrate and the simulated composite substrate are not identical, in a supplementary method step 81 the previous displacement map from the sixth method step 60 is modified, in particular by mathematical means, to generate a new displacement map and the simulation is started again with the new displacement map. Optionally, it is possible to start the method from the beginning with a new substrate for the specified model. In this case, the method is started again from the first method step 10.

[0058] Figure 2 again shows the schematic representation of the measurement and simulation steps of Figure 1. Components that appear twice in one method step are always referenced only once. Method steps that are not performed by the analysis device and / or simulation device are shown in the left column, and method steps that are performed by the analysis device and / or simulation device are shown in the right column. [Explanation of symbols]

[0059] 1...First substrate 2...Second board 4...Composite board 5...Simulated composite board 6…Preliminary displacement map 6'...Displacement map 8...Analysis equipment and / or simulation equipment 10...First method step 20...Second method step 30...Third method step 40...Fourth method step 50...5th method step 60...6th method step 70...7th method step 80...Eighth method step 81... Supplementary method steps 90... 9th method step

Claims

1. 1. A method for providing a displacement map (6) suitable for use for qualitative evaluation after the joining process is completed, comprising: Providing a first substrate (1) and a second substrate (2); measuring the first substrate (1) to determine at least a first geometric parameter, in particular a first macroscopic and / or microscopic geometric parameter, and measuring the second substrate (2) to determine at least a second geometric parameter, in particular a second macroscopic and / or microscopic geometric parameter; bonding the first substrate (1) to the second substrate (2) to form a composite substrate (4); measuring the bonded composite substrate (4) to determine at least one measured third geometric parameter; providing at least one simulated third geometric parameter for the bonded composite substrate (4) based on a composite model, the simulated third geometric parameter being simulated by an analysis and / or simulation device (8) based on the composite model in response to the at least one first geometric parameter, the at least one second geometric parameter, and a preliminary displacement map (6') indicating local deviations from a desired ideal position, the preliminary displacement map (6') being generated by the analysis and / or simulation device (8) and preferably being adapted to compensate for deviations between the simulated third geometric parameter and the measured third geometric parameter in the composite model; comparing the at least one simulated third geometric parameter with the at least one measured third geometric parameter; providing the preliminary displacement map (6') as a displacement map (6) such that the deviation between the simulated third geometric parameter and the at least one measured third geometric parameter is minimal.

2. 2. The method of claim 1, wherein the preliminary displacement map (6') is adjusted at least once to find the preliminary displacement map (6') having a minimum deviation between the simulated third geometric parameter and the at least one measured third geometric parameter.

3. 3. The method according to claim 1 or 2, wherein in a preparation method step, the composite model is determined and provided.

4. 4. The method according to claim 1, wherein the at least one first geometric parameter and / or the at least one second geometric parameter and / or the third geometric parameter comprises a thickness as a function of position, a locally measured curvature as a function of position, and / or a global curvature of the first substrate (1) and / or the second substrate (2).

5. The displacement map (6) is determined for a first set of parameters describing a first bonding process and an additional displacement map is determined for a second set of parameters describing a second bonding process, the method further comprising: comparing the displacement map with the additional displacement map; 5. The method according to claim 1, further comprising the step of: establishing a set of parameters to be used for a third bonding process, said set of parameters being dependent on a comparison between said displacement map (6) and said additional displacement map.

6. 6. The method according to claim 1, wherein at least one parameter of the first set of parameters and / or the second set of parameters is measured during the bonding process by at least one measuring device.

7. The method of claim 6 , wherein the change in time of at least one parameter during the bonding process is determined by the at least one measuring device.

8. 7. The method according to any one of claims 4 to 6, wherein at least one parameter of the first set of parameters comprises temperature, pressure and / or flow rate during bonding, more preferably measured by a single measuring device.

9. 9. The method according to any one of the preceding claims, wherein the first substrate (1) and the second substrate (2) are unstructured.

10. 10. The method according to any one of the preceding claims, wherein the thickness of the first substrate (1) and / or the thickness of the second substrate (1) has a value between 100 nm and 5000 μm, more preferably between 100 nm and 800 μm, most preferably between 100 nm and 500 μm.

11. 11. A method for setting parameters for a joining process, wherein a displacement map (6) is created for setting said parameters, and parameters for the joining process are determined based on said displacement map (6), said displacement map (6) being provided by a method according to any one of claims 1 to 10.

12. A composite substrate (4) manufactured from a first substrate and a second substrate in a bonding process using parameters determined according to the method of claim 11.

13. 12. An apparatus for measuring a first substrate (1), a second substrate (2) and / or a composite substrate (4), comprising at least one analysis and / or simulation device (8) suitable and adapted to carry out the method according to any one of claims 1 to 11.

14. 14. Apparatus according to claim 13, comprising means for bonding the first substrate (1) and the second substrate (2) into a composite substrate (4), in particular for carrying out the method according to claim 11.

15. 15. Apparatus according to claim 13 or 14, comprising means for taking a full surface interferometric image.

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