Method for bonding a first substrate to a second substrate, device for bonding, substrate holder for such a device, and sensor element

Abstract

Method for bonding a first substrate (10) to a second substrate, wherein the first substrate has a primary section and the second substrate (10) has a secondary section, wherein, during bonding of the first substrate to the second substrate (10), a bonding wave advancing along a bonding direction is formed between -- a first subsection in which the first substrate and the second substrate (10) are bonded and -- a second subsection in which the first substrate and the second substrate (10) are yet to be bonded, wherein a subregion of the second substrate (10) in the second subsection is offset in height relative to a subregion of the second substrate (10) in the first subsection in a direction perpendicular to a main extension plane, and wherein, prior to and / or during bonding, in order to determine the state of an object, light is directed onto a surface of the object and reflected and the light reflected by the surface is measured by means of a sensor element (15) for determining the distance of the sensor element (15) to the surface and a distance (a) of the sensor element (15) to the surface is determined.

Description

[0001] Method for bonding a first substrate to a second substrate, device for bonding, substrate holder for such a device and sensor element

[0002] The present invention relates to a method for bonding a first substrate to a second substrate, a device for bonding, a substrate holder for such a device and a sensor element.

[0003] In the semiconductor industry, substrates of different sizes, shapes, and materials are regularly joined together. This joining process is called bonding. Bonding is roughly divided into permanent and temporary bonding. In permanent bonding, a permanent bond is created between the two substrates. This permanent bond is achieved through the interdiffusion of metals, through cation-anion transport in anodic bonding, or through the formation of covalent bonds between oxides and / or semiconductor materials in fusion bonding. In temporary bonding, so-called bonding adhesives are predominantly used. These are adhesives that are applied to the surface of one or both substrates using a coating process to act as an adhesion promoter between the substrates.

[0004] In fusion bonding, two substrates are joined together in an initially detachable connection, a prebond. This prebond is formed primarily by van der Waals bridge bonds between the two highly pure, flat, and, as far as possible, defect- and particle-free substrate surfaces, which are brought into close contact with each other. Hybrid bonding is a subtype of fusion bonding. Hybrid bonding represents the connection of two substrate surfaces, each consisting of an electrical and a dielectric substrate region. The corresponding correlating (dielectric) substrate regions are connected to each other using a fusion bond (prebond). When the prebond is converted into a permanent bond, permanent electrical contact is created between the electrical substrate regions of the substrates. In all bonding methods, bonders are used to join the substrates to be bonded together.The two substrates to be joined can undergo pretreatments such as surface activation, a cleaning step, an alignment step, until the actual prebond step takes place.

[0005] During the prebonding step, the substrate surfaces are brought into contact with each other over a very small area. In other words, the joining reaction is initiated, after which the joining reaction, i.e., the formation of the bridge bonds, can proceed without external energy input. The joining process occurs continuously through the propagation of a bonding wave. The theoretical background is described in US 7,479,441 B2, US 8,475,612 B2, US 6,881,596 B2, and WO 2014 / 191033.

[0006] If the bond wave is initiated centrally between two identical, unstructured substrates, it ideally propagates as a concentrically growing circular front along the substrate radius. Structured substrates, defects, etc., alter the path of the bond wave. Under suboptimal conditions, non-bonded areas (voids) can arise between the two substrates, e.g., due to gas inclusions, particle inclusions, etc.

[0007] Under suboptimal conditions, structures on the substrates or the anisotropy of the substrate material can alter the path of the bonding wave. Any change in the path of the bonding wave can be measured by a person skilled in the art as an alignment error on the joined substrate stack. Furthermore, joining errors can arise as a result of alignment errors (particularly from the following error components: scaling errors, run-out errors), rotation errors, translation errors, residual errors, and temperature compensation errors. Undetected or non-critical errors in the individual substrates, or in particular in functional units manufactured using thin-film technology, can accumulate in an error propagation and only become detectable and quantifiable after the pre-bonding process.

[0008] Although the substrates can be aligned very precisely using alignment equipment, substrate distortions can occur during the bonding process itself. Due to these distortions, the functional units will not necessarily be correctly aligned at all positions. Alignment inaccuracies at a specific point on the substrate can be the result of distortion, a scaling error, a lens error (magnification or reduction error), etc. In the semiconductor industry, all topics dealing with such problems are subsumed under the term "overlay." A relevant introduction to this topic can be found, for example, in: Mack, Chris. Fundamental Principles of Optical Lithography - The Science of Microfabrication. WILEY, 2007, Reprint 2012.

[0009] Every functional unit is designed on a computer before the actual manufacturing process. For example, circuit paths, microchips, MEMS, or any other structure that can be manufactured using microsystems technology are designed in a CAD (computer-aided design) program. During the production of the functional units, however, it becomes apparent that there is always a discrepancy between the ideal, computer-designed functional units and the actual, cleanroom-produced functional units. These differences are primarily due to hardware limitations, i.e., engineering problems, but very often to physical constraints.

[0010] For example, the resolution accuracy of a structure produced using a photolithographic process is limited by the size of the photomask apertures and the wavelength of the light used (electromagnetic radiation). Mask distortions are directly transferred into the photoresist and thus into the fabricated structures. Motion devices such as guides with their coupled drive systems can move to reproducible positions within a specified tolerance, etc. Therefore, it is not surprising that the functional units of a substrate cannot exactly match the computer-designed structures.

[0011] Therefore, all substrates already have a non-negligible deviation from the ideal state before the bonding process.

[0012] If one now compares the positions and / or shapes of two opposing functional units of two substrates, i.e. a first substrate and a second substrate, assuming that neither of the two substrates is distorted by a bonding process, one finds that in general there is already an imperfect registration of the functional units, since these deviate from the ideal computer model due to the errors described above. The most common errors are presented in https: / / commons.wikimedia.org / wiki / File%3AOverlay - typical model terms DE.svg , 24.05.2013 and Mack, Chris. Fundamental Principles of Optical Lithography - The Science of Microfabrication. Chichester: WJLEY, p. 312, 2007, Reprint 2012. According to the figures, one can roughly distinguish between global and local, or symmetric and asymmetric overlay errors. A global overlay error is homogeneous, and therefore independent of location.It produces the same deviation between two opposing functional units regardless of position. The classic global overlay errors are errors I and II, which arise from a translation or rotation of the two substrates relative to each other. The translation or rotation of the two substrates produces a corresponding translational or rotational error for all opposing functional units on the substrates. A local overlay error arises location-dependently, primarily due to elasticity and / or plasticity problems, in this case primarily caused by the continuously propagating bond wave. Of the overlay errors shown, errors III and IV are referred to as "run-out" errors. This error is primarily caused by a distortion of at least one substrate during a 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. Errors I and II can also arise from a bonding process, but are usually so heavily overshadowed by errors III and IV that they are difficult to detect or measure.

[0013] A system already exists in the prior art that can at least partially reduce local distortion. This involves local equalization through the use of active control elements. Such a system is described, for example, in EP 2 656 378 B1.

[0014] Other approaches to correcting run-out errors already exist in the prior art. US 2012 0 077 329 A1 describes a method for achieving a desired alignment accuracy between the functional units of two substrates during and after bonding. The resulting run-out errors are usually radially symmetrical around the contact point, thus increasing from the contact point to the periphery. In most cases, the run-out errors increase linearly. Under special conditions, the run-out errors can also increase nonlinearly.

[0015] Under particularly good conditions, the run-out errors can not only be determined by appropriate measuring instruments (EP 2 463 892 B1), but can also be described, or at least approximated, by mathematical functions. Since the overlay errors represent translations and / or rotations and / or scalings between well-defined points, they are preferably described by vector functions. In general, this vector function is a function f:R2->R2, and therefore a mapping rule that maps the two-dimensional definition domain of the spatial coordinates to the two-dimensional value range of run-out vectors. Although an exact mathematical analysis of the corresponding vector fields has not yet been performed, assumptions are made regarding the functional properties. The vector functions are most likely at least C Ann>= 1 , functions, therefore at least once continuously differentiable. Since the run-out errors increase from the contact point to the boundary, the divergence of the vector function is likely to be non-zero. The vector field is therefore most likely a source field.

[0016] Many defects such as gas inclusions or scaling errors are primarily attributable to the prebonding step, particularly the path of the bond wave or the nature and / or design and / or functionality of the respective substrate chuck. Methods are known in the prior art that provide quantitative information about the path of the bond wave.

[0017] The most commonly used method for monitoring the bonding process is to observe the path of the bond wave using optical means, particularly camera systems, and specifically using a transmitted-light method, particularly in the infrared spectrum. The substrates must be sufficiently transparent to observe the bond wave. Although this method is common practice, it has disadvantages. Not all substrates are suitable for transmitted-light processes; metallizations in particular prevent the observation of the bond interface, which occurs when the two substrate surfaces to be joined are connected. Furthermore, doping in semiconductor substrates can influence the transmittance of electromagnetic radiation. In addition, a transmitted-light process places special demands on all substrate holders, as they must also be transparent to the radiation, which can also cause problems with the reproducibility of the results.

[0018] All previously known techniques for measuring the bond wave path observe the prebonding process directly through the substrates or measure the effect of the attractive force at which the substrates are joined. Currently, there is no precise, commercially available measuring method or measuring device that can observe the bond wave path with high spatial resolution for all substrates, regardless of their material properties, and / or can be used to calibrate the bonding device. Therefore, it is an object of the invention to disclose an improved device and method for measuring and influencing the bond wave during the fusion bonding of two substrates.

[0019] The present invention solves this problem with a method for bonding a first substrate to a second substrate according to claim 1 and with a bonding device according to claim 11, as well as a substrate holder according to claim 14 and a sensor element according to claim 15. Advantageous developments of the invention are specified in the subclaims. The scope of the invention also includes all combinations of at least two features specified in the description, the claims, and / or the drawings. For specified value ranges, values ​​within the specified limits are also to be considered disclosed as limit values ​​and can be claimed in any combination.

[0020] According to a first aspect, a method for bonding a first substrate to a second substrate is provided, wherein the first substrate has a primary section and the second substrate has a secondary section, wherein during bonding of the first substrate to the second substrate a bonding wave advancing along a bonding direction is formed between

[0021] -- a first section in which the first substrate and the second substrate are connected, and

[0022] -- a second subsection in which the first substrate and the second substrate are still to be connected is formed, wherein a subregion of the second substrate in the second subsection is offset in height relative to a subregion of the second substrate in the first subsection in a direction running perpendicular to a main extension plane, wherein before and / or during bonding, in order to determine the state of an object, light is directed onto a surface of the object and reflected and the light reflected from the surface is measured by means of a sensor element in order to determine the distance between the sensor element and the surface and a distance between the sensor element and the surface is determined.

[0023] In contrast to the methods known from the prior art, reflected light from the surface of an object, for example from the back of the second substrate, is used to determine the state of the object, for example the second substrate. In particular, the method proves to be particularly advantageous because different objects or object types with different optical properties can be measured, especially if they have a certain reflectivity for the light used. In this case, it is advantageous to limit the design to a method with which several objects can be measured with the same sensor element. For example, in addition to determining the state of the second substrate during bonding, it is also possible to determine the alignment of the substrate holders for the first substrate before bonding with the same sensor element.All of this can be achieved with a single design feature on the bonding device, particularly with the sensor element for detecting the reflected light. This is not possible, for example, if a transillumination method is provided for the second substrate, since a substrate holder for the first substrate or a first substrate generally cannot be transilluminated. In this case, an alternative measurement method would be required. Preferably, the method is designed to determine the condition of two different objects.

[0024] Furthermore, determining the distance using reflected light has proven particularly advantageous because it makes it possible to determine the distance between the sensor element and the surface as accurately and reliably as possible. State determination is understood to mean, in particular, the current position or orientation of at least a partial section of the object, for example the second substrate or a substrate holder of the first or second substrate, before or during bonding, particularly preferably in the region of the bonding wave or in an area adjacent to the bonding wave. The approach of using reflected light to determine the state has proven particularly advantageous because it is possible even when the object, for example the second substrate, is not transparent to a wavelength with which the second substrate is examined.The method according to the invention thus proves to be particularly advantageous compared to methods in which, for example, transillumination of the second substrate is provided. Such a procedure known from the prior art is ultimately limited to second substrates with a certain transparency for the wavelength used. In the following, the second substrate and the upper substrate on the one hand and the first substrate and the lower substrate on the other hand are preferably used synonymously. The state determination also includes, for example, an at least locally detected distance between the primary section of the first substrate and the secondary section of the second substrate. It is also conceivable that the object, for example the second substrate, is modified on its surface in such a way that its reflectivity is increased, in particular compared to an unmodified surface.For example, a coating that increases reflectivity is conceivable.

[0025] It is preferably provided that at least one optical fiber element is used as a component of the sensor element, and wherein a fiber-optic distance sensor is preferably used as the sensor element. The use of a fiber element allows the light to be guided to an area that is comparatively close to the second substrate or the object, whereas, for example, a light source that generates heat can be as far away from the second substrate or the object as possible. This advantageously prevents the light source and its heat generation from affecting the second substrate or the object to be measured. It is also conceivable that an interferometric sensor system is used to determine the distance, or a system in which the travel times of light pulses are determined by superimposing them and then used to determine the distance. This also makes it possible to detect particularly slight displacements orRegister the change in distance. The light used is preferably laser light. A preferred wavelength can be used that is advantageous for maximum reflection from the object or several different objects and / or for coupling into the fiber element.

[0026] A particular advantage of fiber optics is that the number of sensor elements per unit area, i.e. the sensor element area density, can be greatly increased, which enables an enormous improvement in resolution accuracy. Sensor elements used in the prior art are very large and bulky, as they are usually installed on the substrate holder together with the electronics. For this purpose, it is preferably provided that fiber elements are provided in which fiber ends are provided for signal reception. Furthermore, the fiber elements comprise signal transmission sections, which are provided, for example, for signal guidance. The signal transmission sections are preferably provided for light transmission and / or for the transmission of electrical signals. This advantageously makes it possible to arrange the fiber ends on a substrate holder or in its vicinity. This makes it possible to increase the density of fiber ends in the region of the substrate holder.This has a positive effect on spatial resolution. The signal transmission sections allow an evaluation device to be placed at a sufficiently large distance from the fiber end. In other words, the placement of signal converters or evaluation devices on the substrate holder can be advantageously avoided.

[0027] The preferred sensor element is a fiber optic distance sensor. The fiber optic distance sensor comprises at least one radiation source, an optical fiber, and an evaluation unit. The optical fiber comprises at least two fibers or two fiber bundles. One fiber is used as a line for coupling the radiation from the radiation source to the substrate, and one fiber is used to output the modified measurement signal and feed it to the evaluation unit. The evaluation unit calculates, in particular, the course of the bond wave from the change in the measured value of the particularly calibrated fiber optic distance sensor.

[0028] The measured signal of the fiber optic distance sensor is preferably a change in intensity, which is correlated with a distance or change in distance. The distance between the fiber and the reflecting surface is measured using the characteristic function of the reflected intensity. In other words, the fiber optic distance sensor is used for the non-contact measurement of a distance or a fine displacement between the sensor and a surface to be scanned, in particular the back of a substrate or the surface of the substrate holder. Distance differences or distances of less than 5 nanometers and / or frequencies of over 100 MHz can be detected non-contact with fiber optic distance sensors. The fiber optic measuring system allows working distances in the micrometer to centimeter range with high distance and temporal resolution.The radiation beam emitted from an optical fiber is reflected off the measurement object, in particular the back of the substrate, by a second optical fiber and converted into an electrical voltage by optoelectronic converters. The distance-dependent imaging of the radiation beam onto the receiver-side optical fiber directs different radiation currents to the receiver, i.e., the evaluation unit. The course of the voltage-distance characteristic curve is determined by the optical imaging behavior and the photometric distance law. The optical imaging behavior can be approximately described by the mean light ray. This ray emerges in the center of the transmitting optical fiber, strikes the measurement object, in particular the back of the substrate, at a specific angle between the optical fibers, and reaches the receiving optical fiber at the same angle through reflection.The intensity curve can be described as a function of the angle of incidence using a sine function. The length of the light path also influences the intensity. The intensity I decreases quadratically with the distance a, whereby the distance between the fiber element and the measurement object, in particular the first and / or second substrate, is to be measured. If the model is to be described more precisely, all beam paths must be included integrally in addition to the central beam. The light intensity on the measurement object can be described in simplified terms using the following equation: l(measurement object) = K' * sin(angle of incidence a) * 1 / a. A 2

[0029] The angle α is the angle between the incident or reflected beam and the surface of the measurement object, in particular the back of the substrate. The constant K' or K represents a system constant that essentially depends on the properties of the optical fibers and the reflection properties of the measurement object.

[0030] Since the light now travels from the measuring object or the surface of the object to the receiver, the equation must be applied once more. The intensity that is present at the receiver and evaluated in the evaluation unit corresponds qualitatively to the following curve: l(receiver)=K * sin(angle of incidence a) * (1 / a A 2) * sin(angle of incidence a) * (1 / a A 2)

[0031] The distance sensor can be operated in two operating ranges. In the ascending range, the sensor has a higher sensitivity (slope) than in the descending range. A disadvantage of fiber optic distance measurement is the requirement for relatively large measuring areas. These areas can be reduced by making the optical fibers or fiber elements smaller. However, reducing the size would result in a reduction in the luminous flux in the optical fiber. As a result, not enough light energy can be coupled into the receiver to generate a sufficiently high signal. This problem is reduced by using an entire fiber bundle instead of two optical fibers. Half of the optical fibers are used to output the light, while the other half of the bundle is used to couple the radiation to the receiver. The distribution of the individual fibers can be stochastic.

[0032] The light source is located at the beginning of the signal path. The wavelength of the light must be adapted to the optical fibers, the surfaces to be scanned, in particular substrates and / or substrate holders, and the optoelectronic converter used as the evaluation unit. The radiation source is preferably an LED. The LED can be operated with direct current. In alternative embodiments of the device, radiation feeds with oscillating radiation or light can also be advantageously used. The radiation constantly changes its intensity. This type of modulation, or lock-in, has the advantage of eliminating interference and potential error sources such as temperature drift and / or ambient brightness. The radiation source is coupled into the optical fibers in a suitable manner. Integrated arrangements (LED - optical fiber) are common.The radiation can be transmitted over greater distances to the surface to be scanned. This is preferred in the bonding device according to the invention, as it allows heat sources to be kept away from the substrates to be bonded.

[0033] The receiving optical fiber is arranged directly next to the transmitting optical fiber. The entry and exit surfaces of the optical fibers are ground flat to prevent direct light transmission across the fiber. Thus, at least two fiber elements are preferably provided.

[0034] In particular, an adjustable, particularly angle-dependent, mounting of a sensor head of the sensor element with the optical fibers in the substrate holder is provided. Transmission via the optical fiber, i.e., the fiber element, can also be realized over longer distances in the receiver section, thus advantageously forming a functionally integrated unit comprising a radiation source and an evaluation unit.

[0035] The signal path for measuring the bond wave during fusion bonding begins with a radiation source, preferably an LED. In this disclosure, light is referred to in particular as visible light, and electromagnetic radiation invisible to the human eye is referred to as radiation; however, those skilled in the art will understand that light and radiation are largely interchangeable terms in this disclosure. Where LEDs are referred to as the radiation source below, it will be apparent to those skilled in the art that other radiation sources may also be involved. The light or radiation from the LED is coupled into the fiber bundle, transmitted, and reaches, in particular, the surface of the back of the substrate to be measured. From there, the emitted light is reflected, in particular, at the back of the substrate, and coupled into the receiving fiber. The optical fibers terminate at the optoelectronic evaluation unit, where they couple the light in.The optoelectronic converter can, in particular, be a phototransistor, a photodiode, or a secondary electron multiplier (SEv), which converts the optical signal into an electronic signal. The generated electrical signal currents or signal voltages are preferably subsequently amplified by operational amplifiers. The resulting signals, particularly analog ones, can be connected to a data line after analog-to-digital conversion and further processed, stored, and / or displayed, particularly with computer support.

[0036] Preferably, a set distance between the sensor element and the surface of the object is between 10 pm and 1000 pm, preferably between 10 pm and 500 pm, and particularly preferably between 10 pm and 200 pm. For example, the sensor element can be moved to a (rough) distance within the corresponding value range in order to be able to determine distance values ​​with the highest possible resolution. The set distance is understood to be the distance assumed when aligning the sensor element with respect to the surface to be measured.

[0037] A target value for the position to be approached, in particular an alignment mark, is an ideal value. A movement device used to move a substrate holder approaches the ideal value. Reaching a defined range around the ideal value can be understood as reaching the target value. A positioning device is understood as a coarse positioning device if the approach and / or repeat accuracy deviates from the target value by more than 0.1%, preferably more than 0.05%, particularly preferably more than 0.01%, based on the entire travel path or rotation range, a full rotation of 360 degrees in the case of rotary drives capable of rotation.

[0038] For example, a coarse positioning device with a travel distance of more than 600 mm (twice the substrate diameter) results in a positioning accuracy of 600 mm * 0.01%, i.e. more than 60 micrometers as residual uncertainty.

[0039] In other embodiments of coarse positioning, the residual uncertainty of the approach or repeatability accuracy is less than 100 micrometers, preferably less than 50 micrometers, particularly preferably less than 10 micrometers. Thermal disturbances should also be taken into account. However, this is known to those skilled in the art. A coarse positioning device only fulfills the positioning task with sufficient accuracy if the deviation between the actually achieved actual position and the desired position value lies within the travel range of an associated fine positioning device.

[0040] An alternative coarse positioning device only fulfills the positioning task with sufficient accuracy if the deviation between the actual position actually reached and the setpoint value of the position is half the travel range of an associated fine positioning device.

[0041] A positioning device is understood as a fine positioning device if the residual uncertainty of the approach and / or repeat accuracy of the setpoint value does not exceed less than 500 ppb, preferably less than 100 ppb, ideally 1 ppb based on the entire travel path or rotation range.

[0042] Preferably, a fine positioning device will have an absolute positioning error of less than 5 micrometers, preferably less than 1 micrometer, particularly preferably less than 100 nm, most particularly preferably less than 10 nm, optimally less than 5 nm, ideally less than 1 nm.

[0043] Preferably, at least one positioning device with high accuracy and reproducibility is provided. A concept of mutual error correction can be used to ensure the quality of the alignment of the substrate to the other substrate. Thus, a known offset (rotation and / or displacement) of a substrate and the corresponding positioning device can be used to increase the alignment accuracy by adjusting and correcting the position of the other substrate using correction values ​​or correction vectors. The size and type of rotation and / or displacement determines how the control or regulation uses coarse and fine positioning, or only coarse or only fine positioning, for error correction.

[0044] In a preferred embodiment of the device, the substrates can be deformed and / or tempered using mechanical actuating elements and / or piezo elements, i.e. deformation elements, in order to minimize offset during bonding. The targeted change in temperature changes the shape and size of at least one of the substrates. The targeted change in the shape of the substrate holder changes the shape of the substrate fastened thereon. In the following, positioning devices (coarse, fine, or composite positioning devices) and alignment means are considered synonyms. The alignment of the first substrate to the second substrate can preferably take place in all six degrees of freedom of movement: three translations according to the coordinate directions x, y, and z, and three rotations about the coordinate directions. According to the invention, the movements can be carried out in any direction and orientation.Robots for substrate handling and substrate stack handling are classified as motion devices. The clamping devices can be integrated into the motion devices as components or functionally integrated.

[0045] Furthermore, the device for the floor preferably includes control systems and / or evaluation systems, in particular computers, in order to carry out the described steps, in particular movement sequences, embossing and separation, to carry out corrections, to analyze and store operating states of the device according to the invention.

[0046] In particular, it is provided that an arrangement of a plurality of sensor elements is used for spatial resolution, preferably more than 10 sensor elements, particularly preferably more than 30 sensor elements, and particularly preferably more than 50 sensor elements. This makes it possible to determine a corresponding, particularly locally resolved, orientation of at least a partial area of ​​the object or of the entire object based on the respectively recorded distances between the sensor element and the object. The sensor elements are preferably distributed in a predetermined pattern, for example, a checkerboard pattern or on circular paths.

[0047] It is particularly preferably provided that a higher spatial resolution can be achieved by the increased number of sensor elements. The sensor elements are preferably arranged in a two-dimensional arrangement. The sensor elements are preferably arranged along imaginary circular paths, in particular when bonding starts from a center of the substrates. It is particularly preferably provided if a sensor surface element is constant, preferably in the radial direction. This makes it possible to ensure a homogeneous spatial resolution. The adjacent sensor elements are particularly preferably arranged equidistant from one another at least along one direction. An average distance between adjacent sensor elements is preferably less than 5 cm, preferably less than 2.5 cm and particularly preferably less than 1.5 cm. In this case, the average is taken over all distances between adjacent sensor elements.In particular, the sensor element is designed to receive signals and transmit the received signal to an evaluation device. In the case of a fiber optic cable, several fiber ends can be arranged side by side, and the fiber elements run individually or in bundles to a common evaluation device, which is spaced apart from the fiber ends aligned for signal reception.

[0048] It is particularly preferred if the object is the first substrate or the second substrate. Determining the condition of the second substrate during bonding proves particularly advantageous because the measurement allows for the detection of any progression of the bonding wave and any deformation of the second substrate during bonding. This allows, for example, for the bonding process to be adjusted in real time. The first substrate is preferably examined prior to bonding to verify its correct alignment.

[0049] It is preferably provided that, for temporal resolution, a plurality of state determinations are measured to determine a state change recorded over time, in particular to detect a bond wave development of the second substrate, during bonding. This makes it possible, for example, to detect a bond wave, in particular with regard to its temporal development, for example to determine a bonding speed. For this purpose, in particular, a displacement of the rear side of the second substrate during bonding is measured and determined. For this purpose, preferably more than ten sensors, particularly preferably more than 30 sensors, very particularly preferably more than 50 sensors are used, which are integrated in particular equidistantly on the substrate holder.In particular, it is therefore provided that an arrangement of a plurality of sensor elements is used for spatial resolution, preferably more than 10 sensor elements, particularly preferably more than 30 sensor elements, and particularly preferably more than 50 sensor elements. This arrangement preferably covers a two-dimensional section. Preferably, at least one fiber-optic distance sensor is used to measure the bond wave, wherein the fiber-optic distance sensor is mounted in a statically determined manner, and wherein the adjustment of the fiber-optic distance sensor takes place without twisting the fiber and / or the fiber-optic distance sensor.

[0050] In particular, the spatial and local progression of a bond wave can be recorded or determined from a multitude of measured values ​​from sensors distributed across the substrate surface, thus enabling the progression of the bond wave to be influenced in a closed-loop control system. For this purpose, the recorded position data of the bond wave as well as the anisotropies and / or anomalies, in particular distortions or deformations, are compared, in particular, with a computer-aided model of the ideal bond wave progression. By controlling the individual vacuum zones (time and extent of the pressure change, in particular the release of an individual zone), the observed error during bonding, in particular during fusion bonding, is corrected promptly, in particular in real time.

[0051] The radiation coupling and evaluation take place outside the substrate holder, preferably in a separate evaluation unit. The end of the light guide is mounted in the substrate holder, preferably in the upper substrate holder itself, so that the back of the substrate is within the working range of the sensors during the bonding process.

[0052] In an exemplary method, the temporal and spatial progression of a bond wave during fusion bonding can be determined. The distance between the back of the upper substrate and the upper substrate holder is determined over time, stored, visualized, and / or taken into account in the form of correction factors to correct alignment errors. The distances and / or distance changes are measured as a function of time, in particular synchronized with over 50 sensors. In a particularly preferred embodiment of the device, 52 fiber-optic distance sensors can be distributed across the substrate holder to enable close monitoring of the bond wave.

[0053] Preferably, it is provided that an alignment, for example a position and / or an orientation, of the second substrate is determined during and / or after it is accommodated in a substrate holder for state determination. For example, it is provided that the state determination is used to minimize the distance to be set between the first substrate and the second substrate before bonding. An exemplary method provides for the measurement of the local deviations and scattering of the vertical distance during the alignment of a lower substrate and an upper substrate to one another before bonding, in particular fusion bonding. The vertical distance during alignment is also referred to as the bond gap and serves to ensure that the substrates can be aligned to one another with as minimal a distance as possible, without touching one another.Local variations in the vertical distance can arise due to the manufacturing tolerances of the substrate holder, especially the upper substrate holder. Measurement series of different substrates on the same substrate holders using fiber optic distance sensors can be used to identify local unevenness and / or shape deviations of the substrate holders, allowing for correction of the respective substrate holders.

[0054] It is preferably provided that the bonding is influenced depending on the state determination, in particular a bond wave speed is controlled or regulated. In a preferred method, the control or preferably the regulation of the bond waveform can be enabled. The distance measurement values ​​of the fiber optic distance sensors during bonding of the upper substrate to the lower substrate are correlated with the control of individually switchable vacuum zones on the upper substrate holder in particular in such a way that the bond wave can pass through in particular in one plane with as little distortion as possible and wherein the substrate-related asymmetries and / or anisotropy can be compensated in order to achieve an optimal, as distortion-free as possible bonding result. The measurement of the bond as an overlay measurement on the finished substrate stack can be taken into account as a further correction in the bonding process.A further advantage of using fiber optic distance sensors is that the precise adjustment of the working distance with the inventive adjustment using fine adjustment elements such as backlash-free micrometer screws, which can position the optical fiber in a particularly force-free manner, allows for sensors with higher accuracy but with a smaller measuring range. This reduces bonding errors, as smaller device travels result in smaller alignment errors.

[0055] According to a preferred embodiment, it is provided that the object is a component of a device for carrying out the method, for example a holding element and / or a deformation element of the device and / or a loading pin.

[0056] In an exemplary method, a position, in particular a parallelism, of the upper substrate holder to the lower substrate holder is determined. It has surprisingly been found that instead of adjusting the flatness based on the measurement results from three dynamic pressure sensors or optical sensors, in particular those offset by 120 degrees, worse local distortions during bonding can be achieved than adjusting the parallelism of the entire substrate holder surfaces to one another in a separate optimization process with the goal of achieving the most globally uniform parallel alignment of the upper substrate holder to the lower substrate holder from the local distance values. For the actual adjustment, fine adjustment elements such as micrometer screws, in particular fine-thread screws, can be used to locally change the substrate holder surfaces to one another.In other words, a global optimum of parallelism across the entire surface of the substrate holder is calculated and adjusted using the multitude of locally measured distances between the substrate holders. As the parallelism of the substrate holder surfaces improves, the bonding results between individual bond modules improve, thus increasing the reproducibility and repeatability of bonding processes between devices with fiber optic distance sensors.

[0057] Preferably, it is provided that the state determination of the second substrate is used to determine a fixing and / or actuating means with which the first substrate and / or the second substrate is held and / or supplied to the bonding.

[0058] Another method involves monitoring or determining the adjustment of the loading pins of the lower substrate holder. Finally, in a variation of the third application, the fiber optic distance sensors can be used to measure the parallelism of the loaded lower substrate to the upper substrate holder and adjust it accordingly.

[0059] Another exemplary method provides for the shape of the upper or second substrate to be observed or determined during loading of the upper substrate holder. From the shape of the upper substrate during loading, conclusions about the bonding behavior, such as an expected deflection or sagging of the upper substrate, can be derived and taken into account during bonding, in particular the distance between the upper substrate and the lower substrate must be adjusted prior to bonding so that the upper substrate and the lower substrate do not undesirably touch each other during alignment, yet a small working distance can be achieved.

[0060] Another exemplary method provides that the lower and / or the upper substrate, i.e. the first and / or the second substrate, is observed and recorded during attachment to the respective substrate holder, in particular in such a way that deformations of the respective substrate can be recorded in a timely and spatially correlated manner when the vacuum is applied. In particular, the controls for the vacuum zones can be adjusted both in the switching sequence and with the vacuum level used in order to be able to bond the substrates with as little distortion as possible. A particularly important aspect in this regard is that the substrates can be deformed in a targeted manner for bonding before bonding with attachment to the substrate holder in order to compensate for and / or reduce known distortions of the respective substrate.In other words, the plane parallelism of the upper substrate to the lower substrate is not necessarily considered the best starting position for a successful and optimally aligned fusion bond, but measured and appropriately deformed substrates are bonded together by means of fusion bonding in such a way that the resulting substrate stack has the smallest possible alignment errors.

[0061] Another exemplary method provides for adaptive loading of the substrates by using the measured values ​​of the fiber-optic distance sensors in the upper substrate holder to actively control individually switchable, in particular isolated, vacuum segments of the upper and / or lower substrate holder, so that the sequence and force of the suction result in substrates that are as distortion-free as possible. In another embodiment, the substrates can be deformed in a targeted manner. A person skilled in the art can independently deduce this from the application described here. Thus, the natural variation in the substrate properties is immediately compensated for by measuring the substrate during loading and attachment to the substrate holder.

[0062] Furthermore, all applications can be automatically visualized, especially with computer support, so that process engineers or technicians can more quickly detect and eliminate potential sources of error.

[0063] A further aspect of the present invention is a device for bonding a first substrate to a second substrate, in particular by means of a method according to one of the preceding claims, wherein the first substrate has a primary section and the second substrate has a secondary section, wherein the device is configured such that during bonding of the first substrate to the second substrate a bonding wave advancing along a bonding direction between

[0064] -- a first section in which the first substrate and the second substrate are connected, and

[0065] -- a second subsection in which the first substrate and the second substrate are still to be connected is formed, wherein a subregion of the second substrate in the second subsection is offset in height relative to a subregion of the second substrate in the first subsection in a direction running perpendicular to a main extension plane, wherein the device comprises a sensor element, wherein the device comprises a sensor element, wherein the device for determining the state of an object is designed such that before and / or during bonding for determining the state of an object, light is directed onto a surface of the object and reflected, and the light reflected from the surface is measured by means of a sensor element for determining the distance between the sensor element and the surface, and a distance between the sensor element and the surface is determined.All advantages and properties described for the process can be transferred analogously to the device.

[0066] In a first embodiment of the measuring device, the optical fibers of the sensor head are installed. The sensor head contains both the optical fibers that guide the radiation from the radiation source to the substrate and the optical fibers for coupling out the measurement signal. The optical fibers are installed in the sensor head so that they can be adjusted independently of each other. The optical fibers are not twisted, allowing the respective working distance and measuring range to be precisely adjusted. For this purpose, spring-loaded or spring-loaded, backlash-free adjustment elements, such as preloaded micrometer screws, in particular, backlash-free preloaded differential screw gears, can be used.

[0067] Since fiber optic distance sensors have ground fiber ends and the manufacturing accuracy of the optical fiber, and thus of the sensors, is finite, the measurement uncertainty resulting from the undefined angular position of an optical fiber is at least reduced, preferably eliminated, with the present invention. This is because the optical fibers are installed in the sensor head at a specific angular position, at least without twisting them. Thus, distances and distance changes can be measured with less uncertainty, so that the path of the bond wave can be precisely recorded and controlled accordingly. For this purpose, the sensors can be integrated into the substrate holder, particularly with zero-play click or zero-play bayonet connections.

[0068] In particular, it is provided that the sensor element has a fiber end and a signal transmission section, wherein the sensor element is designed such that the fiber end is provided for signal reception and the signal transmission section is provided for signal transmission to a spaced-apart evaluation device.

[0069] Particularly advantageous in the device with the structural separation of the radiation source and the evaluation unit from the sensor head, a large number of sensors can be installed in the substrate holder. By miniaturizing the adjustment and the entire sensor head in particular, the number of sensor heads used in the device can be advantageously increased, allowing for close monitoring of the bond wave both temporally and spatially. The radiation sources and evaluation units are preferably placed far away from the substrate holder.

[0070] The adjustment of the fiber optic distance sensors installed in the substrate holder, especially the upper substrate holder, is carried out using a calibration and adjustment procedure. The calibration involves the following steps, particularly the following procedure.

[0071] Preferably, the optical fiber element is aligned for calibration. In a first method step, for example, an upper substrate is loaded onto the upper substrate holder and secured. In a second method step, the fiber optic distance sensors are adjusted, in particular iteratively, so that the respective sensor has at least a minimal distance to the back of the second substrate. In a third method step, the individual sensors are read out and the intensity signals and / or the distances are stored. In a fourth method step, the stored intensity signals are set as zero distance. In a fifth method step, the upper substrate is detached from the upper substrate holder and unloaded from the bonding space of the bonder. In a sixth method step, a lower substrate is loaded onto the lower substrate holder and secured.In a seventh process step, the distances from the fiber optic distance sensors in the upper substrate holder - and thus from the upper substrate holder - to the bonding interface of the lower substrate on the lower substrate holder are measured. In an eighth process step, the upper substrate holder and / or the lower substrate holder are moved to a different working distance. In a ninth process step, particularly at the same time as the eighth process step, both the change in the distance between the upper substrate holder and the lower substrate holder as well as the distance between the upper substrate holder and the lower substrate holder are recorded. In a tenth process step, the actual distances are compared with the target value of the distance change between the upper and lower substrate holders, and the differences are recorded for each sensor in order to record the specific correction values ​​of the fiber optic distance sensors as well as the intensity curves.In the eleventh process step, the calibration is iteratively recorded as a series of measurements with exchanged substrates in order to create the correction values ​​of the fiber optic distance sensors as a knowledge store and / or database. The curves approximated to the set of points of the intensity values ​​at given distances are called intensity curves. In particular, the intensity curves can be approximated using empirical mathematical formulas, so that the expected intensities can be interpolated for a given distance between the substrate holders in the bonding device. Conversely, the distances are determined for each sensor from the measured intensities.

[0072] Exchanging substrates for calibration means that a statistically relevant number of measurements are performed with different substrates. In particular, variations in substrate thickness, variations in reflectance within a material, as well as variations in material differences or variations due to different positioning on the substrate holders can be captured and used as correction values ​​for measuring the bond wave and thus for influencing the bond wave. This allows system- and substrate-specific correction values ​​to be determined.

[0073] This means that during fusion bonding, all possible distances between the upper substrate holder and the lower substrate holder can be better detected spatially and temporally in the working range of the fiber optic distance sensors.

[0074] In particular, the bonding process is influenced depending on the state determination, in particular the bonding wave speed is controlled. For this purpose, deformation and / or fixing elements are specifically controlled, and a portion of the second substrate is dropped or held.

[0075] Preferably, the bonding process can be influenced based on the state determination by drawing on insights from a machine learning algorithm and / or empirical values ​​stored in a database. To utilize the measured state determinations obtained over a large number of bonding processes, the recorded state determinations, together with a result of the bonding process, can be made available as a test set to a neural network. Based on the test sets, the neural network develops new strategies for controlling the bonding process for specific state determinations and preferably applies them in the next bonding process for comparable state determinations. This allows the method to be used to further optimize the bonding process.

[0076] Preferably, the sensor element comprises at least one optical fiber element and preferably comprises a fiber-optic distance sensor. It is particularly preferred that the at least one optical fiber element be integrated into the device in a displaceable, in particular pivotable, manner.

[0077] The device for bonding substrates comprises in particular the following functional components and / or modules:

[0078] -Substrate holder: Substrate holders are used for the substrate holder. In particular, at least one substrate holder equipped with sensors and actuators is used for this purpose. Further, particularly independent inventions include an improved device with a substrate holder with at least one, preferably with more than 30 sensors and 30 actuators for influencing the bonding wave. In particularly preferred embodiments of the device, substrate holders have more than 50 sensors and 50 actuators.

[0079] The bonding device preferably comprises at least one fiber optic distance sensor as sensors, preferably the same number of fiber optic distance sensors as the number of independently switchable vacuum zones. In particular, the fiber optic distance sensors can be adjustably integrated into the substrate holder, in particular into the upper substrate holder.

[0080] In particular, the substrate holders have individually switchable, fluidically isolated zones, in particular vacuum zones, which are each assigned to a fiber optic distance sensor. In particular, the fiber optic distance sensor is integrated in the respective vacuum zone, so that the measurement of the attachment of a substrate and the vacuum control are connected to one another in the shortest control loop, and the measurement of the deformation of the substrate takes place where the effect of the vacuum zone deforms the substrate. The substrate holders have fixations. The fixations serve to hold the substrates. The fixations can be

[0081] 1. Mechanical fixations, especially

[0082] 1.1. Terminals

[0083] 2. Vacuum fixations, especially with

[0084] 2.1 . individually controllable vacuum tracks

[0085] 2.2. interconnected vacuum tracks

[0086] 3. Electrical fixations, especially

[0087] 3.1. Electrostatic fixations

[0088] 4. Magnetic fixations

[0089] 5. Adhesive fixations, especially

[0090] 6. Gel-Pak Fixations

[0091] 7. Fixations with adhesive, particularly controllable, surfaces.

[0092] The fixations are, in particular, electronically controllable. Vacuum fixation is the preferred fixation type. Vacuum fixation preferably comprises several vacuum tracks that emerge at the surface of the substrate holder. The vacuum tracks are preferably individually controllable. In a technically more feasible application, several vacuum tracks can be combined to form vacuum track segments that can be individually controlled and thus evacuated or flooded. However, each vacuum segment is independent of the other vacuum segments. This makes it possible to construct individually controllable vacuum segments. The vacuum segments are preferably ring-shaped. However, any shape is conceivable as a vacuum zone. This enables the targeted fixation and / or detachment of a substrate from the substrate holder.

[0093] The device according to the invention with fiber optic distance sensors can be used, among others, for the following possible applications, which are particularly considered as independent inventions: -Movement and / or alignment means for the substrates with the actuating elements, actuators for the force generation for changing the substrate curvature.

[0094] In one embodiment of the device, the movement means for receiving the substrates can deform the substrates reproducibly.

[0095] -Movement and / or alignment means for the substrate, such as coarse and / or fine drives,

[0096] -Bond initiation agents for fusion bonding, in particular pins, fluidic pressure media, in particular nozzles with gas overpressure, and / or combinations thereof,

[0097] -Movement and / or alignment means are understood in the device according to the invention preferably as movement devices with drive systems, guide systems, holding devices and measuring systems in order to move, position and align the optical systems and / or substrates with each other.

[0098] The movement devices can generate each movement as a result of individual movements, so that the movement devices can preferably contain fast coarse positioning devices that do not meet the accuracy requirements as well as precise fine positioning devices.

[0099] Fiber optic distance sensors offer particular advantages for use as measuring devices in bonding fixtures: the optical fiber enables a compact design, allowing a high density of measuring devices to be integrated into substrate holders. Retrofitting bonding fixtures is also possible, as the evaluation unit and the radiation source do not need to be placed directly on the substrates and / or substrate holders. A further advantage is the high achievable data density compared to conventional measurement methods such as laser or confocal sensors.

[0100] Furthermore, according to an advantageous embodiment, a device can comprise supply and auxiliary and / or supplementary systems (compressed air, vacuum, electrical energy, fluids such as hydraulics, coolants, heating means, means and / or devices for temperature stabilization, electromagnetic shielding, ionizers and / or deionizers, electrostatic dust traps).

[0101] Furthermore, a device according to the invention includes frames, cladding, and active or passive subsystems that suppress, damp, or eliminate vibrations. A frame can be understood as a component, particularly made of natural hard stone, mineral casting, spheroidal graphite cast iron, or hydraulically bonded concrete, which is particularly vibration-damped and / or vibration-isolated and / or installed with vibration damping.

[0102] Furthermore, a device according to the invention comprises at least one measuring system, preferably with measuring units for each movement axis, which can be designed in particular as displacement measuring systems and / or as angle measuring systems. Furthermore, the device includes at least one measuring system, preferably with measuring units for radiation intensity, in particular for the radiation for curing the embossing compound.

[0103] Furthermore, the device comprises at least one measuring system for observing and / or checking the adjustment or alignment marks of the first substrate and the second substrate.

[0104] Furthermore, the device comprises at least one measuring and control system for pressure, in particular vacuum and / or overpressure, which measures, detects and controls the pressure on / in the substrate during bonding.

[0105] Furthermore, a device according to the invention includes at least one measuring system for monitoring the alignment of the substrates relative to one another. These are provided, for example, in addition to determining the distance via reflected light.

[0106] Both tactile (i.e., probing) and non-tactile measurement methods can be used. The measurement standard, the unit of measurement, can be a physical object, particularly a scale, or it can be implicit in the measurement process, such as the wavelength of the radiation used.

[0107] To achieve alignment accuracy before bonding, at least one measuring system can be selected and used. Measuring systems implement measuring methods. In particular,

[0108] • Inductive methods and / or

[0109] Capacitive processes and / or

[0110] Resistive methods and / or • Comparison methods, in particular optical image recognition methods, detection of position marks and / or QR codes and / or

[0111] • incremental or absolute methods (in particular with glass standards as scale, or interferometers, in particular laser interferometers, or with magnetic standards) and / or

[0112] • Runtime measurements (Doppler method, time of flight method) or other time recording methods and / or

[0113] • Triangulation methods, especially laser triangulation,

[0114] • Autofocus method and / or

[0115] • Intensity measurement methods such as fiber optic rangefinders are used.

[0116] For example, measured values ​​can be combined and / or referenced and / or correlated with each other, so that a measurement of one alignment mark can be used to determine the position of the related other alignment mark. In particular, the position of the substrate can be calculated from the position values ​​of the substrate holder and the detected alignment marks and corrected accordingly.

[0117] For position determination, in particular 3D position determination at one point, two points, three points, or any number of points, a first embodiment of the invention can utilize optical pattern recognition using camera systems to provide a unique reference of the position and height. The patterns are recorded in a real-time system, in particular continuously during the alignment of the substrates. The measurement methods listed can also be used for position determination.

[0118] Preferably, movement devices that are not used for fine adjustment are designed, in particular, as robotic systems, preferably with incremental displacement sensors. The accuracy of these movement devices for auxiliary movements is decoupled from the accuracy for aligning the substrates, so that the auxiliary movements are carried out with a low repeatability of less than 1 mm, preferably less than 500 micrometers, particularly preferably less than 150 micrometers. The accuracy of the movement devices for alignment is preferably less than 200 nm, preferably less than 100 nm, particularly preferably less than 50 nm, very particularly preferably less than 20 nm, optimally less than 10 nm, ideally less than 1 nm.

[0119] In particularly preferred embodiments of the device, the error of the alignment accuracy of the device is 20% of the permissible maximum alignment error, particularly preferably 10% of the permissible maximum alignment error, in the optimal case 1%.

[0120] Processes are preferably created as recipes and executed in machine-readable format. Recipes are optimized collections of values ​​for parameters that are functionally or procedurally related. The use of recipes allows for the reproducibility of production processes.

[0121] In one embodiment of the bonding method, a lower substrate is fusion bonded to an upper substrate, with the following sequence, in particular with the following steps:

[0122] In a first process step, the lower substrate is placed on a lower substrate holder and measured with at least one fiber optic distance sensor, which is installed in the upper substrate holder.

[0123] In a second process step, the lower substrate is fixed to the lower substrate holder, in particular with vacuum zones, and the fixing is measured with at least one fiber optic distance sensor as an additional control, so that the local deformations of the lower substrate are preferably minimized.

[0124] In a third method step, the upper substrate is loaded into the bonding device and measured in free form with at least one fiber optic distance sensor in order to detect and, in particular, correct deformations and / or critical distortions of the upper substrate.

[0125] In a fourth process step, the upper substrate is attached to the upper substrate holder, particularly by means of vacuum zones, and measured using at least one fiber optic distance sensor. Through the controlled attachment of the upper substrate, unwanted distortions and / or deformations of the upper substrate can be minimized, preferably eliminated. In a fifth process step, the substrates are aligned to one another, particularly using alignment marks.

[0126] In a sixth process step, a fusion bond is initiated by contacting the upper substrate and the upper substrate. The fusion bond can be initiated, in particular, with a bond pin. The initiation of the bond wave can be monitored with at least one fiber optic distance sensor to ensure the bond wave travels in a controlled manner.

[0127] In a seventh process step, the path of the bonding wave is monitored using at least one fiber optic sensor in the upper substrate holder. The distance between the back of the upper substrate and the upper substrate holder is recorded and / or stored as a function of time and / or fed into a bonding wave control system, in particular the vacuum zone control system, and / or visualized and / or processed and / or statistically evaluated.

[0128] In an eighth process step, the course of the bonding wave is influenced, in particular in real time to the seventh process step, by influencing the vacuum of at least one vacuum zone of a substrate holder in order to minimize distortions during bonding.

[0129] In a ninth process step, the fusion bonding of the substrate stack is completed, and the upper substrate holder is separated from the upper substrate. This process step can optionally be performed in conjunction with the seventh and / or eighth process steps.

[0130] In a tenth process step, the bonded substrate stack in the prebond is removed from the bonding device and, in particular, subjected to a quality control.

[0131] To the extent that device features are disclosed here and / or in the subsequent description of the figures, these should also be considered disclosed method features, and vice versa. All numerical values ​​and relationships (parallelism, congruence, normality, flatness, etc.) in this disclosure are used as terms for quantities subject to tolerances, so that in particular the non-tolerated length or angular dimensions according to ISO 2768 and the semi-standards relevant to the semiconductor industry (for flatness, waviness, deflection, particle load, etc.) apply, unless the tolerances are explicitly stated. A further subject matter of the present invention is a substrate holder for a device according to the invention, wherein the sensor element is integrated into the substrate holder. All advantages and properties described for the device can be transferred analogously to the substrate holder and vice versa.

[0132] A further subject of the present invention is a sensor element for integration into a device according to the invention or a substrate holder according to the invention. All advantages and properties described for the device can be applied analogously to the substrate holder and the sensor element, and vice versa. In particular, it is envisaged that the sensor element can be used to upgrade existing devices. For example, the sensor element is dimensioned such that it can be inserted into a recess that was or is originally intended as a vacuum opening or opening for a deformation element. This merely requires placing the sensor element in the corresponding recess and securing it.

[0133] Further advantages, features, and details of the invention will become apparent from the following description of preferred embodiments and from the drawings. These show:

[0134] Fig. 1 is a schematic diagram of a fusion bonding device with an integrated fiber optic distance sensor.

[0135] Fig. 2 is a schematic representation of a section of a substrate holder with an integrated fiber optic sensor.

[0136] In the figures, advantages and features of the invention are identified by reference numerals identifying them in accordance with embodiments of the invention, wherein components or features with the same or equivalent function are identified by identical reference numerals.

[0137] The figures are to be understood as sketches, from which no size relationships or scales can be derived. They may show the relationships of the parts to each other in an exaggerated representation, which is used for illustrative purposes.

[0138] Fig. 1 shows parts of a device 1 for fusion bonding. The bonding device 1 includes a frame 8, on which the optical detection means 3 for the lower substrate 11 can be mounted on a movable frame 2 with the movement device 4. In particular, the optical detection means 7 for detecting an alignment mark of an upper substrate, which is not shown, is located in the same optical axis as the optical detection means 3. The movable frame 5 and the movement device 6 enable the optical detection means 7 to be focused on the alignment mark.

[0139] The lower substrate holder 9 can accommodate the lower substrate 11. The vacuum segments and the vacuum channels of the substrate holder 9 are not shown. The necessary substrate movements for loading and unloading, as well as for adjustment, can be performed using the movement device of the lower substrate holder 10.

[0140] The upper substrate holder 12 can accommodate the upper substrate (not shown). The vacuum segments and the vacuum channels of the upper substrate holder 12 are not shown. The necessary substrate movements for loading and unloading as well as for adjustment can be carried out using the movement device of the upper substrate holder 13. The bond pin 14, which starts the fusion bond after the substrates approach, is shown schematically. A fiber optic distance sensor 15 is shown, with two fictitious, overlapping beams 16, with the aid of which the distance a can be measured, in particular between the upper substrate holder 12 and the substrate 11 or between the upper substrate holder 12 and the lower substrate holder 9 or between the upper substrate holder 12 and the upper substrate. The other fiber optic distance sensors as well as the radiation sources and evaluation units are not shown.In particular, the expert understands a sensor element embodied as a fiber to be a component whose fiber end is intended for receiving light or signals. These signals are then forwarded to a common evaluation device, which, as a comparatively large component, is spaced apart from the sensor element. Here, the signals from several fibers with adjacent fiber ends preferably converge to be evaluated together in the common evaluation device.

[0141] Fig. 2 shows a section of an upper substrate holder 12' in a top view, schematically illustrating the functional surface. Two fibers of the fiber optic distance sensor are shown at 15'. The vacuum nozzle 17 is fluidly connected to the vacuum control system, allowing the applied vacuum to be regulated. A schematically illustrated sealing lip 18 delimits the illustrated vacuum zone. Another similar vacuum zone with the same elements is shown without markings.

[0142] List of reference symbols:

[0143] 1 device for bonding substrates

[0144] 2 Movable frame of the upper optical detection means

[0145] 3 Upper optical detection device

[0146] 4 Movement device of the upper optical detection means

[0147] 5 Movable frame of the lower optical detection means

[0148] 6 Movement device of the lower optical detection means

[0149] 7 Lower optical detection device

[0150] 8 frame

[0151] 9 Lower substrate holder

[0152] 10 Movement device of the lower substrate holder

[0153] 11 Lower substrate

[0154] 12, 12' Upper substrate holder

[0155] 13 Movement device of the upper substrate holder

[0156] 14 Bond pin

[0157] 15.15' fibers

[0158] 16 Symbolic measuring radiation of the fiber optic distance sensor

[0159] 17 Vacuum nozzle

[0160] 18 Vacuum seal, sealing lip

Claims

Claims 1 . Method for bonding a first substrate to a second substrate (10), wherein the first substrate has a primary section and the second substrate (10) has a secondary section, wherein during bonding of the first substrate to the second substrate (10) a bonding wave advancing along a bonding direction between -- a first section in which the first substrate and the second substrate (10) are connected, and -- a second subsection is formed in which the first substrate and the second substrate (10) are still to be connected, wherein a subregion of the second substrate (10) in the second subsection is preferably at least temporarily offset in height during bonding compared to a subregion of the second substrate (10) in the first subsection in a direction running perpendicular to a main extension plane, wherein before and / or during bonding, in order to determine the state of an object, light is directed onto a surface of the object and reflected, and the light reflected by the surface is measured by means of a sensor element (15) to determine the distance between the sensor element (15) and the surface, and a distance (a) between the sensor element (15) and the surface is determined.

2. Method according to claim 1, wherein at least one optical fiber element is used as a component of the sensor element (15) and wherein a fiber optic distance sensor is preferably used as the sensor element (15).

3. Method according to one of the preceding claims, wherein a set distance between the sensor element (15) and the surface of the object assumes a value between 10 pm and 1000 pm, preferably between 10 pm and 500 pm and particularly preferably between 10 pm and 200 pm.

4. Method according to one of the preceding claims, wherein an arrangement of a plurality of sensor elements (15) is used for spatial resolution, preferably of more than ten sensor elements (15), particularly preferably from more than 30 sensor elements and particularly preferably from more than 50 sensor elements (15) and / or at least one sensor element (15).

5. Method according to one of the preceding claims, wherein the object is the first substrate or the second substrate (10).

6. The method according to claim 5, wherein a plurality of state determinations are recorded during bonding to determine a state change recorded over time, in particular to detect a bond wave development on the second substrate (10).

7. Method according to one of the preceding claims, wherein the bonding is influenced depending on the state determination, in particular a bonding wave speed is controlled.

8. Method according to one of the preceding claims, wherein the state determination is used to minimize a distance to be set between the first substrate and the second substrate (10) before bonding.

9. Method according to one of claims 5 to 8, wherein an orientation of the second substrate (10) and / or the first substrate is determined during and / or after its inclusion in an associated substrate holder (10, 12) for state determination.

10. Method according to one of the preceding claims, wherein the object is a component of a device (1) for carrying out the method, for example a substrate holder (9, 12) and / or a deformation element of the device (1).

11. Device (1) for bonding a first substrate to a second substrate (10), in particular by means of a method according to one of the preceding claims, wherein the first substrate has a primary section and the second substrate (10) has a secondary section, wherein the device is configured such that during bonding of the first substrate to the second substrate (10) a bonding wave advancing along a bonding direction between -- a first section in which the first substrate and the second substrate (10) are connected, and -- a second subsection in which the first substrate and the second substrate are still to be connected, in particular for detecting a bond wave development of the second substrate (10), wherein a subregion of the second substrate (10) in the second subsection is offset in height from a subregion of the second substrate (10) in the first subsection in a direction running perpendicular to a main extension plane, wherein the device comprises a sensor element (15), wherein the device for determining the state of an object is designed such that before and / or during bonding, in order to determine the state of an object, light is directed onto a surface of the object and reflected, and the light reflected from the surface is measured by means of a sensor element (15) for determining the distance between the sensor element and the surface, and a distance (a) between the sensor element (15) and the surface is determined.

12. Device (1) according to one of the preceding claims, wherein the sensor element (15) has at least one optical fiber element and preferably comprises a fiber optic distance sensor, wherein an arrangement of a plurality of sensor elements (15) is preferably used for spatial resolution, preferably of more than ten sensor elements (15), particularly preferably of more than 30 sensor elements and particularly preferably of more than 50 sensor elements (15) and / or at least one sensor element (15).

13. Device (1) according to claim 12, wherein the sensor element (15) has a fiber end and a signal transmission section, wherein the sensor element (15) is designed such that the fiber end is provided for signal reception and the signal transmission section is provided for signal transmission to a spaced evaluation device.

14. Substrate holder (12) for a device according to one of claims 10 to 13, wherein the sensor element (15), in particular its fiber end, is integrated into the substrate holder (12).

15. Sensor element (15) for integration into a device (1) according to one of claims 1 to 13 or a substrate holder (12) according to claim 14.

Images