A method for joining a first substrate to a second substrate, a joining apparatus, a substrate holder for such apparatus, and a sensor element.

Abstract

A method for joining a first substrate (10) to a second substrate, wherein the first substrate includes a primary section and the second substrate (10) includes a secondary section, and when joining the first substrate to the second substrate (10), a joining wave propagating along the joining direction is formed between a first subsection where the first substrate and the second substrate (10) are joined and a second subsection where the first substrate and the second substrate (10) are not yet joined, and a portion of the second substrate (10) in the second subsection is offset in the height direction relative to a portion of the second substrate (10) in the first subsection in a direction perpendicular to the main extending plane, and for the purpose of determining the state of the object, light is directed towards the surface of the object and reflected before and / or during joining, and the light reflected by the surface is measured by a sensor element (15) for determining the distance between the sensor element (15) and the surface, and the distance (a) between the sensor element (15) and the surface is determined.

Description

Technical Field

[0001] The present invention relates to a method for bonding a first substrate to a second substrate, a bonding apparatus, a substrate holder for such an apparatus, and a sensor element.

Background Art

[0002] The semiconductor industry routinely bonds substrates of different sizes, shapes, and materials. This bonding process (German: verbindungsvorgang, English: joining process) is referred to as bonding. Bonding is broadly classified into permanent bonding and temporary bonding. Permanent bonding forms an inseparable bond between two substrates. This permanent bond is produced by the interdiffusion of metals, by cation-anion transport in anodic bonding, or by the formation of covalent bonds between oxides and / or semiconductor materials in fusion bonding. So-called adhesives are mainly used for temporary bonding. These are adhesives that are applied using a coating process to the surface of one or both substrates in order to function as an adhesive between the substrates.

[0003] In fusion bonding, two substrates are initially joined to each other by a separable bond, i.e., a preliminary bond. This preliminary bond is mainly formed by van der Waals crosslinking between the surfaces of two high-purity substrates that are brought into close contact with each other and are free of defects and particles. Hybrid bonding is a subspecies of fusion bonding. Hybrid bonding represents the bonding of two substrate surfaces each composed of an electrical substrate region and a dielectric substrate region. The corresponding correlated (dielectric) substrate regions are joined to each other using fusion bonding (preliminary bonding). When the preliminary bond is converted into a permanent bond, a permanent electrical contact is formed between the electrical substrate regions of the substrates.

[0004] In all bonding methods, a bonding apparatus is used to bond the substrates to be bonded. The two substrates to be bonded can be subjected to pretreatment such as surface activation, cleaning steps, alignment steps, etc. until the actual preliminary bonding step is performed.

[0005] During the pre-bonding step, the substrate surfaces are in contact with each other in very small areas. In other words, a bonding reaction is initiated, and thereafter, without the supply of external energy, the bonding reaction, i.e., the formation of a cross-linked bond, proceeds. The bonding process is carried out continuously by the propagation of a bonding wave (German: Bondwelle, English: bond wave). The theoretical background is described in Patent Documents 1, 2, 3, and 4.

[0006] When a junction wave is initiated at the center of two identical unstructured substrates, it ideally propagates along the substrate radially as a circular front that grows concentrically. Structured substrates, impurities, etc., alter the path of the junction wave. Under suboptimal conditions, unbonded regions, or voids, may form between the two substrates, for example, due to gas inclusions, particulate inclusions, etc.

[0007] Under suboptimal conditions, the structure on the substrate or the anisotropy of the substrate material can alter the propagation path of the bond wave. Those skilled in the art can measure this change in the bond wave propagation path as alignment error on the bonded substrate stack. Furthermore, bond errors can arise as a result of alignment errors (particularly the following error components: scaling error, runout error), rotational errors, translational errors, residual errors, and temperature compensation errors. In particular, undetected or non-critical errors in individual substrates or functional units manufactured using thin-film technology can accumulate as error propagation and can only be detected and quantified after the pre-bonding process.

[0008] While substrates can be aligned with extreme precision using an aligner, distortion can occur in the substrate during the bonding process itself. This resulting distortion means that functional units may not be perfectly aligned with each other at all locations. Misalignment at specific points on the substrate can be a result of distortion, scaling errors, or lens errors (magnification or reduction errors).

[0009] In the semiconductor industry, all matters addressing such problems are encompassed under the term "overlay." An introduction to this field can be found, for example, in Non-Patent Document 1.

[0010] Each functional unit is designed on a computer before the actual manufacturing process. For example, conductive paths, microchips, MEMS, or any other structures that can be manufactured using microsystem technology are designed in a CAD (computer-aided design) program. However, it has been shown that during the manufacturing of functional units, there is always a deviation between the ideal functional unit designed on the computer and the functional unit actually manufactured in the cleanroom. This difference is mainly due to hardware limitations, i.e., engineering problems, but very often it is due to physical limitations.

[0011] For example, the resolution accuracy of structures produced by a photolithography process is limited by the aperture dimensions of the photomask and the wavelength of the light (electromagnetic radiation) used. Mask distortion is directly transferred to the photoresist and, consequently, to the manufactured structure. Moving devices such as guides coupled with a drive system can be moved to reproducible positions within specified tolerances. Therefore, it is not surprising that the functional units of the substrate are not exactly identical to the structures designed on the computer.

[0012] Therefore, all substrates already have a significant deviation from the ideal state prior to the bonding process. Here, when comparing the positions and / or shapes of two opposing functional units on two substrates, i.e., the first substrate and the second substrate, assuming that neither substrate is distorted by the bonding process, it is generally recognized that an imperfect match of the functional units already exists, due to the aforementioned errors causing a deviation from the ideal computer model. The most common errors are described in https: / / commons.wikimedia.org / wiki / File%3 AOverlay_-_typical_model_terms_DE.svg,24 / 05 / 2013 and Non-Patent Literature 1. According to these figures, a rough distinction can be made between global overlay errors and local overlay errors, or symmetrical overlay errors and asymmetrical overlay errors. Global overlay errors are uniform and therefore independent of location. This error causes the same deviation between two opposing functional units, regardless of location. Classical global overlay errors are errors I and II, which arise from the relative translation or rotation of the two substrates relative to each other. Translation or rotation of two substrates introduces corresponding translation or rotation errors for all opposing functional units on the substrates. Local overlay errors occur locally, primarily due to elastic and / or plastic issues, and in this case, are mainly caused by continuously propagating bonding waves. Of the illustrated overlay errors, errors III and IV in particular are referred to as “runout” errors. These errors are primarily caused by distortion of at least one of the substrates during the bonding process. Due to the distortion of at least one substrate, the functional units of the first substrate are also distorted relative to the functional units of the second substrate. However, errors I and II can also occur during the bonding process, but are usually very strongly superimposed by errors III and IV, making errors I and II difficult to detect or measure.

[0013] In the prior art, there are already devices that can be used to reduce local distortion at least partially. This involves performing local equalization by using an active control element. Such a device is described, for example, in Patent Document 5.

[0014] Prior art already provides other solutions for correcting runout errors. Patent document 6 describes a method for maintaining desired alignment accuracy between functional units of two substrates during and after bonding. In most cases, the resulting "runout" defect is radially symmetrical with respect to the contact point and therefore increases from the contact point toward the outer edge. In most cases, the runout error increases linearly. Under special conditions, the runout error may also increase non-linearly.

[0015] Under particularly favorable conditions, the “runout” error can not only be determined by the corresponding measuring device (Patent Document 7), but can also be described, or at least approximated, by a mathematical function. The overlay error, representing translation and / or rotation and / or scaling between clearly defined points, is preferably described by a vector function. Generally, this vector function is a function of f:R2->R2, and therefore a mapping rule that maps the two-dimensional defined range of position coordinates to the two-dimensional value range of the “runout” vector. Although a precise mathematical analysis of the corresponding vector field has not yet been performed, several assumptions have been made about the functional properties. The vector function is at least C n It is very likely to be a function of (n≧1), and therefore very likely to be a function that is at least once continuously differentiable. Since the "runout" error increases from the point of contact toward the outer edge, the divergence of the vector function is likely not zero. Therefore, the vector field is very likely to be the source field.

[0016] Many errors, such as gas content or scaling errors, are mainly due to the pre-bonding step, particularly the propagation path of the bond wave or the properties and / or formation and / or function of each substrate holder (chuck). In the prior art, methods for quantitatively evaluating the propagation path of the bond wave are known.

[0017] The most commonly used method for monitoring the bonding process is to observe the propagation path of the bonding wave using optical means, particularly camera systems, especially the transmitted light method, and particularly in the infrared spectrum. The substrate must have sufficient transparency for observation of the bonding wave. Although this method is commonly implemented, it also has drawbacks. Not all substrates are suitable for the transmitted light method, and metallization, in particular, hinders the observation of the bonding interface formed when the two substrate surfaces to be bonded are joined. Furthermore, doping on semiconductor substrates can affect the transmittance of electromagnetic radiation. In addition, the transmitted light method imposes special requirements on all substrate holders, because the substrate holder must also be transparent to radiation, which can also lead to problems with the reproducibility of results.

[0018] All currently known techniques for measuring the propagation path of junction waves involve either directly observing the pre-bonding process through the substrate or measuring the effect of the attractive forces acting when the substrates are bonded. In some cases, there is no accurate, commercially available measurement method or apparatus that can observe the propagation path of junction waves with high spatial resolution for all substrates, regardless of their material properties, and / or can be used to calibrate bonding equipment. [Prior art documents] [Patent Documents]

[0019] [Patent Document 1] U.S. Patent No. 7479441 [Patent Document 2] U.S. Patent No. 8475612 [Patent Document 3] U.S. Patent No. 6,881,596 [Patent Document 4] International Publication No. 2014 / 191033 [Patent Document 5] European Patent No. 2,656,378 Specification [Patent Document 6] U.S. Patent Application Publication No. 2012 / 0077329 Specification [Patent Document 7] European Patent No. 2,463,892 Specification [Non-Patent Document]

[0020] [Non-Patent Document 1] Written by Mark Chris (Mack, Chris), "Fundamental Principles of Optical Lithography - The Science of Microfabrication", Wiley, 312 pages, 2007, reprinted in 2012 [Summary of the Invention] [Problems to be Solved by the Invention]

[0021] Therefore, an object of the present invention is to disclose an improved apparatus and method for measuring and influencing the bonding wave during the fusion bonding of two substrates. [Means for Solving the Problems]

[0022] The present invention achieves the above object by the method for bonding a first substrate according to claim 1 to a second substrate, the bonding apparatus according to claim 11, the substrate holder according to claim 14, and the sensor element according to claim 15. Another advantageous embodiment of the present invention is described in the dependent claims. All combinations of at least two features described in the specification, claims and / or drawings are also included in the scope of the present invention. When a numerical range is described, values within the described limits are also regarded as the disclosed limit values and can be claimed in any combination.

[0023] According to a first embodiment, a method is provided for joining a first substrate to a second substrate, wherein the first substrate comprises a primary section and the second substrate comprises a secondary section. When the first substrate is joined to the second substrate, the joining wave propagating along the joining direction is - A first subsection to which the first substrate and the second substrate are joined, -Formed between the first substrate and the second substrate and the second subsection which are not yet joined, The portion of the second substrate in the second subsection is offset in the height direction relative to the portion of the second substrate in the first subsection, in a direction perpendicular to the main extending plane. For the purpose of determining the state of the object, before and / or during joining, light is directed towards the surface of the object and reflected, and the light reflected by the surface is measured by a sensor element for determining the distance between the sensor element and the surface, thereby determining the distance between the sensor element and the surface.

[0024] In contrast to methods known from the prior art, the state of an object, such as the second substrate, is determined using reflected light from the surface of the object, such as the back surface of the second substrate. This method is particularly advantageous in that it can measure different objects or types of objects with different optical properties, especially when they have a specific reflectivity for the light used. It is advantageous to limit the design to a single method that can be used to measure multiple objects using 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 holder with respect to the first substrate before bonding using the same sensor element. All of this can be achieved by a single design means in the bonding apparatus, particularly a sensor element for detecting reflected light. This is not possible, for example, when a transmitted illumination method is employed for the second substrate, because the substrate holder for the first substrate or the first substrate cannot usually be transmitted illuminated. In this case, an alternative measurement method is required. Preferably, the method is provided for determining the state of two different objects.

[0025] Furthermore, determining distance by reflected light is particularly advantageous in that it provides a method for determining the distance between the sensor element and the surface as accurately and reliably as possible. State determination is understood to mean at least the current position or alignment of a subsection of the object, such as the second substrate or the substrate holder of the first or second substrate, most preferably in the region of the bond wave or a region adjacent to the bond wave, particularly before or during bonding. The procedure of using back-reflected light for state determination is particularly advantageous in that it can be performed even if the object, such as the second substrate, is not transparent to the wavelength being inspected. Thus, the method according to the present invention is particularly advantageous compared to, for example, a method that assumes transmitted illumination of the second substrate. Such procedures known from the prior art are ultimately limited to a second substrate that has specific transparency to the wavelength used. Hereinafter, the second substrate and upper substrate, and the first substrate and lower substrate are preferably used synonymously.

[0026] The state determination also includes, for example, the distance detected at least locally between the primary section of the first substrate and the secondary section of the second substrate. Furthermore, the surface of the object, such as the second substrate, may be modified in such a way that its reflectivity increases compared to the unprocessed surface. For example, a coating that increases reflectivity is a possible approach.

[0027] Preferably, at least one optical fiber element is used as a component of the sensor element, and preferably, an optical fiber distance sensor is provided as the sensor element. The use of a fiber element makes it possible to direct light to a region relatively close to the second substrate or object, while, for example, positioning a heat-generating light source as far away as possible from the second substrate or object. This has the advantage of preventing the light source and its heat generation from affecting the second substrate or object being measured. It is also conceivable to use an interference sensor system to determine the distance, or a system that is determined by superimposing the propagation times of optical pulses and then used to determine the distance. This makes it possible to record particularly minute displacements or distance changes. Preferably, the light used is laser light.

[0028] Preferably, a suitable wavelength can be used that is advantageous for maximum reflection and / or coupling to the fiber element on the target object or multiple different targets. A particularly significant advantage of optical fibers is that they can greatly increase the number of sensor elements per unit area, i.e., the surface density of sensor elements, thereby dramatically improving the accuracy of the resolution. Sensor elements used in conventional technology are usually very large and bulky because they are installed on a substrate holder together with electronic equipment. For this purpose, it is preferable to provide fiber elements with fiber ends provided for signal reception. Furthermore, the fiber elements include a signal transmission section provided, for example, for signal routing. The signal transmission section is preferably provided for optical wave guidance and / or for transmitting electrical signals. This makes it advantageous to place the fiber ends on or near the substrate holder. As a result, the density of fiber ends in the area of ​​the substrate holder can be increased. This has a positive effect on spatial resolution. The signal transmission section makes it possible to place the evaluation device at a sufficiently large distance from the fiber ends. In other words, it is advantageous to avoid placing the signal converter or evaluation device on the substrate holder.

[0029] A suitable sensor element is an optical fiber distance sensor. The optical fiber distance sensor includes at least one radiation source, an optical fiber, and an evaluation unit. The optical fiber includes at least two fibers or two fiber bundles. One fiber is used as a line for coupling radiation from the radiation source to the substrate, and the other fiber is used to extract the modified measurement signal and provide that signal to the evaluation unit. The evaluation unit calculates the propagation path of the bonded wave in particular from the changes in the measurement values ​​of the calibrated optical fiber distance sensor.

[0030] The measurement signal of an optical fiber distance sensor is preferably a change in distance or a change in intensity correlated with a change in distance. The distance between the fiber and the reflective surface is measured via a characteristic function of the reflected intensity. In other words, optical fiber distance sensors are used for non-contact measurement of distance or minute displacement between the sensor and the surface of the probe object, particularly the back surface of a substrate or the surface of a substrate holder. Using an optical fiber distance sensor, distance differences of less than 5 nanometers or distance and / or frequencies above 100 MHz can be detected non-contact. The optical fiber measurement system can operate with high distance and temporal resolution in working distances ranging from micrometers to centimeters. The radiated beam emitted from the optical fiber is reflected from the object to be measured, particularly the back surface of a substrate, and then received by a second optical fiber, where it is converted into a voltage by a photoelectric converter. The distance-dependent mapping of the radiated beam to the receiving optical fiber leads to different radiated currents being directed to the photodetector, i.e., the evaluation unit. The shape 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 beam. This beam originates from the center of the transmitting light guide, enters the object being measured, particularly the back surface of the substrate, at a specific angle between the light guides, and reaches the receiving light guide by reflection at the same angle. The intensity curve can be described by a sine function depending on the angle of incidence. The optical path length further affects the intensity. The intensity I decreases inversely proportional to the square of the distance a, where the distance between the fiber element and the object being measured, particularly the first and / or second substrates, should be measured. For a more accurate description of the model, all beam paths should be comprehensively included in addition to the central beam. The light intensity on the object being measured can be described in a simplified form using the following equation.

[0031] I(Measurement object)=K'*sin(Incidence angle α)*1 / a 2 The angle α is the angle between the incident or reflected beam and the surface of the object being measured, particularly the back surface of the substrate. The constant K' or K represents a system constant that is essentially dependent on the properties of the optical fiber and the reflective properties of the object being measured.

[0032] Here, since a further path of light is created from the object being measured or the surface of the object to the light detector, the above formula must be applied again. The intensity present in the light detector and analyzed by the evaluation unit qualitatively corresponds to the following curve.

[0033] I(receiver)=K*sin(incident angle α)*(1 / a 2 )*sin(incident angle α)*(1 / a 2 ) Distance sensors can operate in two operating ranges. In the upward range, the sensor has higher sensitivity (gradient) than in the downward range. One drawback of optical fiber distance measurement is that it requires a relatively large measurement area. The area can be reduced by reducing the size of the optical fiber or fiber element. However, reducing the size means reducing the light flux within the optical fiber. As a result, there may not be enough light energy coupled to the photodetector to produce a sufficiently high signal. This problem is mitigated by using an entire fiber bundle instead of two optical fibers. Half of the optical fiber is used to extract light, while the other half of the bundle is used to couple the radiation to the photodetector. The distribution of individual fibers may be stochastic.

[0034] The light source is positioned at the starting end of the signal path. The wavelength of the light must be matched to the optical fiber, the surface to be scanned, particularly the substrate and / or substrate holder, and the photoelectric converter used as an evaluation unit. The radiation source may preferably be an LED. The LED may operate on DC. In alternative embodiments of the apparatus, vibrational radiation or optical radiation supply may also be advantageously used. Radiation constantly changes its intensity. This type of modulation or lock-in has the advantage of eliminating interference and potential error sources arising from temperature drift and / or ambient brightness. The radiation source is coupled to the optical fiber in an appropriate form. Integrated devices (LED-optical fiber) are common. Radiation can be transmitted over longer distances to the surface to be scanned. This is preferable in the bonding apparatus according to the present invention, as it allows the heat source to be kept away from the substrate to be bonded.

[0035] The light-receiving optical fiber is positioned immediately adjacent to the light-transmitting optical fiber. The input and output surfaces of the optical fiber are polished flat to avoid direct light transmission across the fiber. Preferably, at least two fiber elements are provided.

[0036] In particular, the substrate holder provides an adjustable, especially angle-dependent, fixation of the sensor head of the sensor element having an optical fiber. Transmission via the optical fiber, i.e., the fiber element, can also be carried out over longer distances on the receiver side, and as a result, a functionally integrated unit consisting of a radiation source and an evaluation unit can be advantageously formed.

[0037] In fusion bonding, the signal path for measuring the junction wave begins with a radiation source, preferably an LED. In this disclosure, light refers specifically to 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 LED is referred to as a radiation source below, it will be apparent to those skilled in the art that other radiation sources may also be included. Light or radiation from the LED is coupled to a fiber bundle and transmitted, in particular to the surface of the back of the substrate to be measured. The light emitted therefrom is reflected, in particular from the back of the substrate, and coupled to a light-receiving fiber. The optical fiber is terminated in a photoelectronic evaluation unit, where the light is coupled. The photoelectric converter may be, in particular, a phototransistor or photodiode or secondary electron multiplier tube that converts the optical signal into an electrical signal. Preferably, the generated electrical signal current or signal voltage is then amplified by an operational amplifier. The signal thus obtained, in particular an analog signal, is connected to a data line after analog-to-digital conversion and may be further processed and / or stored and / or displayed, in particular with computer assistance.

[0038] Preferably, the set distance between the sensor element and the surface of the object is provided to have a value of 10 μm to 1000 μm, more preferably 10 μm to 500 μm, and most preferably 10 μm to 200 μm. For example, the sensor element may be moved to a (coarse) distance within the range of the corresponding value so that the distance value can be determined with the highest possible resolution. The set distance is the distance assumed when the sensor element is aligned with the surface to be measured.

[0039] The target value of the position to be approached, particularly the alignment mark, is an ideal value. The moving device that moves the substrate holder approaches this ideal value. Reaching a defined environment around the ideal value can be understood as reaching the target value. In the case of a rotary drive device capable of full 360° rotation, a positioning device is understood to be a coarse positioning device if its approach accuracy and / or repeatability deviates from the target value by more than 0.1%, more preferably more than 0.05%, and most preferably more than 0.01% of the total travel distance or rotation range.

[0040] For example, a coarse positioning device with a travel distance exceeding 600 mm (twice the substrate diameter) will achieve an approach accuracy of 600 mm * 0.01%, i.e., an approach accuracy with a residual uncertainty of more than 60 micrometers.

[0041] In other embodiments of coarse positioning, the residual uncertainty in approach accuracy or repeatability is less than 100 micrometers, more preferably less than 50 micrometers, and most preferably less than 10 micrometers. Thermal disturbance variables should also be taken into consideration; however, this is well known to those skilled in the art.

[0042] The coarse positioning device fulfills the positioning task with sufficient accuracy only if the deviation between the actual position reached and the target position is within the range of motion of the associated precision positioning device. An alternative coarse positioning device will only satisfy the positioning task with sufficient accuracy if the deviation between the actual position reached and the set position is within half the range of motion of the associated precision positioning device.

[0043] A precision positioning device is understood to be a positioning device in which the residual uncertainty of the approach accuracy and / or repeatability from the set value does not exceed 500 ppb, preferably less than 100 ppb, and ideally less than 1 ppb, with respect to the total travel distance or rotation range.

[0044] Preferably, the precision positioning device has an absolute positioning error of less than 5 micrometers, preferably less than 1 micrometer, more preferably less than 100 nm, particularly preferably less than 10 nm, optimally less than 5 nm, and ideally less than 1 nm.

[0045] Preferably, at least one positioning device having high precision and high repeatability is provided. The concept of mutual error correction can be used for the quality of alignment between one substrate and another. In this way, known offsets (rotation and / or displacement) of the substrates and their corresponding positioning devices can improve alignment accuracy by adjusting and correcting the position of the other substrate using correction values ​​or correction vectors. Whether the control system uses coarse and precise positioning, or coarse positioning only, or precise positioning only for error correction depends on the magnitude and type of rotation and / or displacement.

[0046] In a preferred embodiment of the apparatus, the substrate can be deformed and / or temperature-controlled using mechanical adjustment elements and / or piezoelectric elements, i.e., deformation elements, to minimize offset during bonding. Targeted temperature changes alter the shape and size of at least one of the substrates. Targeted changes in the shape of the substrate holder alter the shape of the substrate mounted in the substrate holder.

[0047] In the following, positioning devices (coarse positioning devices, precision positioning devices, or combined positioning devices) and alignment means are treated synonymously. Alignment of the first substrate with respect to the second substrate can preferably be performed in all six degrees of freedom of movement, including three translations in the coordinate directions x, y, and z, and three rotations around the coordinate directions. According to the present invention, movement can be performed in any direction and orientation. Robots for substrate handling and substrate stack handling may be included in the moving device. Holding fixtures may be integrated into the moving device as components or functionally integrated.

[0048] Furthermore, the base apparatus preferably includes a control system and / or evaluation system, in particular a computer, which performs the described steps, in particular the movement sequence, pressing and separation, performs corrections, and analyzes and stores the operating state of the apparatus according to the present invention.

[0049] In particular, for spatial resolution, an array of multiple sensor elements, preferably more than 10 sensor elements, more preferably more than 30 sensor elements, and more preferably more than 50 sensor elements is provided to be used. This makes it possible to determine the corresponding, particularly locally resolved, alignment of at least a portion of an object or the entire object based on the distance recorded between the sensor elements and the object. The sensor elements are preferably dispersed on a predetermined pattern, such as a checkerboard pattern or a circular path.

[0050] Particularly preferable, higher spatial resolution can be achieved by increasing the number of sensor elements. The sensor elements are preferably arranged in a two-dimensional array. Preferably, the sensor elements are arranged along a virtual circular path, especially when the junction starts from the center of the substrate. Most preferably, the sensor surface elements are provided to be preferably constant in the radial direction. This ensures uniform spatial resolution. Particularly preferable, adjacent sensor elements are arranged equidistant from each other along at least one direction. Preferably, the average distance between adjacent sensor elements is less than 5 cm, more preferably less than 2.5 cm, and most preferably less than 1.5 cm. In this case, all distances between adjacent sensor elements are averaged. In particular, the sensor elements are designed for signal reception and provided to transmit recorded signals to an evaluation device. In the case of optical fibers, multiple fiber ends can be arranged adjacent to each other, and multiple fiber elements, individually or bundled, extend from multiple fiber ends aligned for signal reception to a common evaluation device spaced apart.

[0051] Particularly preferred is the object being bonded to a first substrate or a second substrate. Determining the state of the second substrate during bonding is particularly advantageous because it allows the measurement to detect the propagation of the bonding wave and the deformation of the second substrate during bonding. This makes it possible, for example, to adjust the bonding in real time. The first substrate is preferably inspected before bonding to check for correct alignment before bonding.

[0052] Preferably, with respect to temporal resolution, multiple state determinations are provided to be detected during bonding to determine changes in the state detected over time, in particular to detect the propagation of the bonding wave on the second substrate. This makes it possible, for example, to detect the bonding wave, particularly with respect to its temporal progression, to determine, for example, the bonding speed. For this purpose, in particular, the displacement of the back surface of the second substrate during bonding is measured and determined. For this purpose, preferably more than 10 sensors, more preferably more than 30 sensors, and most preferably more than 50 sensors are used, and these sensors are incorporated equidistant on a substrate holder. Accordingly, in particular for spatial resolution, an array of multiple sensor elements, preferably more than 10 sensor elements, more preferably more than 30 sensor elements, and most preferably more than 50 sensor elements is provided to be used. This arrangement preferably covers a two-dimensional section. Preferably, at least one optical fiber distance sensor is used to measure the bonding wave, the optical fiber distance sensor is fixed in a statically determined manner, and adjustment of the optical fiber distance sensor is performed without twisting the fiber and / or the optical fiber distance sensor.

[0053] In particular, based on numerous measurements from multiple sensors distributed across the substrate surface, the spatial and local propagation path of the junction wave can be detected or determined, thereby allowing the propagation path of the junction wave to be influenced in a closed-loop control system. For this purpose, the detected positional data of the junction wave, as well as anisotropy and / or anomalies, especially strain or deformation, are compared with a computer-aided model of an ideal junction wave curve, and errors observed during bonding, especially during fusion bonding, are quickly, and especially in real time, corrected by controlling individual vacuum zones (the time and degree of pressure changes, especially the release of individual zones).

[0054] Radiation coupling and evaluation are performed outside the substrate holder, preferably in a separate evaluation unit. The ends of the optical fibers are attached to the substrate holder, preferably the upper substrate holder itself, so that the back surface of the substrate is within the operating range of the sensor during the bonding process.

[0055] In an exemplary method, the temporal and local progression of the bond wave during fusion bonding can be determined. The distance of the back surface of the upper substrate to the upper substrate holder is determined over time, stored, visualized, and / or considered in the form of a correction factor to compensate for alignment errors. The distance and / or distance change is measured as a function of time, and in particular, synchronously with more than 50 sensors. In a preferred embodiment of the apparatus, 52 optical fiber distance sensors can be distributed on the substrate holder to enable precise monitoring of the bond wave.

[0056] Preferably, the alignment of the second substrate, such as its position and / or orientation, is provided to be determined during and / or after mounting to the substrate holder for state determination. For example, state determination is provided to be used to minimize the distance set between the first and second substrates before bonding. An exemplary method is provided to measure local deviations and variations in the vertical distance when aligning the lower and upper substrates relative to each other before bonding, particularly fusion bonding. The vertical distance during alignment, also referred to as the bonding gap, is used to ensure that the substrates can be aligned at the smallest possible distance without contacting each other. Local variations in the vertical distance can result from manufacturing tolerances of the substrate holder, particularly the upper substrate holder. By performing a series of measurements using an optical fiber distance sensor with different substrates mounted on the same substrate holder, local non-uniformity and / or shape deviations of the substrate holder can be estimated, thereby allowing for correction of individual substrate holders.

[0057] Preferably, the bonding is affected in a state-dependent manner, and in particular, the bonding wave velocity is controlled or adjusted. In a preferred manner, the bonding waveform can be controlled and preferably adjusted. The distance measurement of the optical fiber distance sensor when bonding the upper substrate to the lower substrate is correlated with the control of individually switchable vacuum zones on the upper substrate holder, in particular, so that the bonding wave passes through a plane with as little distortion as possible, compensating for asymmetry and / or anisotropy associated with the substrate, and achieving the optimal bonding result with the least possible distortion. The measurement results of the bonding apparatus as overlay measurements on the completed substrate stack can be considered as further corrections in the bonding process. A further advantage of using the optical fiber distance sensor is that the working distance can be precisely adjusted by adjustment according to the present invention using fine adjustment elements such as backlash-free micrometer screws, which allows the optical fiber to be positioned without applying excessive force, thus enabling the use of a more accurate sensor with a smaller measurement range. This reduces the travel distance of the apparatus and the error in alignment, thus reducing errors during bonding.

[0058] According to a preferred embodiment, the object is provided to be a component of an apparatus for carrying out the method, for example, a fixing element and / or a deformation element and / or a loading pin of the apparatus. In an exemplary method, the position, particularly the parallelism, of the upper substrate holder relative to the lower substrate holder is determined. Surprisingly, when plane adjustment was performed using measurement results from three dynamic pressure sensors or optical sensors offset by 120°, it was found that local distortion during bonding was actually greater compared to a method of adjusting the parallelism between the substrate holder surfaces in an independent optimization process, with the aim of achieving alignment of the upper substrate holder relative to the lower substrate holder as uniformly as possible overall based on local distance values. In actual adjustment, the relative position of the substrate holder surfaces can be locally changed by fine adjustment elements such as micrometer screws, particularly fine threads. In other words, a globally optimal value for parallelism across the entire surface of the substrate holders is calculated and set from a number of locally measured distances between the substrate holders. By improving the parallelism between the substrate holder surfaces, the bonding results between individual bonding modules are improved, and as a result, the reproducibility and repeatability of the bonding process between devices with optical fiber distance sensors are improved.

[0059] Preferably, the state determination of the second substrate is used to determine the fixing means and / or operating means for holding the first substrate and / or the second substrate and / or supplying them for bonding. A further method provides that the setting of the loading pins of the lower substrate holder can be observed or determined. Finally, in a variation of the third application example, an optical fiber distance sensor can be used to measure the parallelism of the loaded lower substrate to the upper substrate holder and adjust accordingly.

[0060] A further exemplary method provides that the shape of the upper substrate or the second substrate is observed or determined while the upper substrate holder is being loaded. From the shape of the upper substrate during loading, conclusions can be drawn about the bonding behavior, such as the expected deflection or sag of the upper substrate, and it becomes possible to consider what distance should be set relative to the upper substrate before bonding, so that during bonding, in particular during alignment, the upper and lower substrates do not come into unwanted contact and a small working distance can be achieved.

[0061] A further exemplary method provides that the lower and / or upper substrates, i.e., the first and / or second substrates, are observed and detected in such a way that the deformation of each substrate can be detected in a temporally and locally correlated manner during mounting to the respective substrate holders, particularly when a vacuum is applied. In particular, the control of the vacuum zone can be set with respect to both the circuit sequence and the vacuum level used so that the substrates can be joined with as little strain as possible. A particularly important aspect in this regard is that the substrates can be intentionally deformed for joining in order to compensate for and / or reduce known strains of each substrate before joining by mounting to the substrate holders. In other words, the planar parallelism of the upper substrate to the lower substrate is not necessarily considered the best starting position for a successful, optimally aligned fusion bond; rather, the measured and correspondingly intentionally deformed substrates are joined by fusion bonding in such a way that the resulting substrate stack has as little alignment error as possible.

[0062] Another exemplary method provides adaptive substrate loading by actively controlling individually switchable vacuum segments in the upper and / or lower substrate holders, particularly vacuum segments operating independently of each other, using measurements from an optical fiber distance sensor in the upper substrate holder, so that the suction sequence and force result in a substrate that is as distortion-free as possible. In another embodiment, the substrate can be deformed as intended. Those skilled in the art can independently derive this from the applications described herein. In this way, natural variations in substrate characteristics are immediately compensated by measuring the substrate during loading and mounting into the substrate holder.

[0063] Furthermore, since all application forms can be visualized, especially using computer assistance, process engineers or technicians can more quickly detect and eliminate the causes of errors.

[0064] Further aspects of the present invention are apparatus for bonding a first substrate to a second substrate, particularly according to the method of any one of the prior claims, wherein the first substrate comprises a primary section and the second substrate comprises a secondary section, and the apparatus, when bonding the first substrate to the second substrate, has a bonding wave propagating along the bonding direction. - A first subsection to which the first substrate and the second substrate are joined, -Formed between the first substrate and the second substrate and the second subsection which are not yet joined, The portion of the second substrate in the second subsection is offset in the height direction relative to the portion of the second substrate in the first subsection, in a direction perpendicular to the main extending plane. The apparatus is equipped with a sensor element, and for determining the state of an object, the apparatus is designed such that, for determining the state of an object, light is directed towards the surface of the object and reflected, and the light reflected by the surface is measured by a sensor element for determining the distance between the sensor element and the surface, and the distance between the sensor element and the surface is determined. All the advantages and characteristics described for the method can also be applied to the apparatus.

[0065] In a first embodiment of the measuring device, optical fibers are installed in a sensor head. The sensor head includes both optical fibers for guiding radiation from a radiation source to a substrate and optical fibers for extracting measurement signals. The optical fibers are installed in the sensor head so as to be independently adjustable from each other, and are kept free from twisting so that their respective working distances and measurement ranges can be precisely set. For this purpose, elastic or spring-driven backlash-free adjustment elements may be used, such as preloaded micrometer screws, in particular, backlash-free preloaded differential screw gears.

[0066] The optical fiber distance sensor has polished fiber ends, and because there are limits to the manufacturing precision of the optical fiber and therefore the sensor, the uncertainty in measurement due to the indeterminate angular position of the optical fiber is at least reduced, and preferably eliminated, by the present invention. This is because the optical fiber is positioned within the sensor head at a specific angular position and at least without twisting. This means that distance and changes in distance can be detected with less uncertainty, and as a result, the propagation path of the bonded wave can be accurately detected and controlled accordingly. In particular, multiple sensors can be incorporated into a substrate holder by backlash-free click connections or backlash-free bayonet connections.

[0067] In particular, the sensor element is provided with a fiber end and a signal transmission section, and the sensor element is designed so that the fiber end is provided for signal reception and the signal transmission section is provided for signal transmission to evaluation devices arranged at intervals.

[0068] A particularly advantageous feature of this device is that the radiation source and evaluation unit are structurally separated from the sensor head, which allows for the placement of a large number of sensors within the substrate holder. In particular, miniaturizing the adjustment mechanism and the entire sensor head allows for a favorable increase in the number of sensor heads used within the device, enabling precise observation of the junction wave in both temporal and spatial contexts. The radiation source and evaluation unit are preferably positioned away from the substrate holder.

[0069] The adjustment of the optical fiber distance sensor mounted on the substrate holder, particularly the upper substrate holder, is performed using a calibration and adjustment procedure. For calibration, the following steps, in particular the following sequence, are performed.

[0070] Preferably, the optical fiber elements are aligned for calibration. In a first method step, for example, the upper substrate is loaded and mounted in the upper substrate holder. In a second method step, the optical fiber distance sensors are adjusted particularly iteratively so that each sensor has at least a minimum distance from the back surface of the second substrate. In a third method step, the individual sensors are read out and the intensity signal and / or distance is stored. In a fourth method step, the stored intensity signal is set as the zero distance. In a fifth method step, the upper substrate is released from the upper substrate holder and ejected from the bonding chamber of the bonding apparatus. In a sixth method step, the lower substrate is loaded and mounted in the lower substrate holder. In a seventh method step, the distance from the optical fiber distance sensor 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 is measured. In an eighth method step, the upper substrate holder and / or the lower substrate holder are moved to different working distances. In the ninth method step, and particularly simultaneously with the eighth method step, the change in distance between the upper and lower substrate holders, and the distance between the upper and lower substrate holders are recorded. In the tenth method step, the actual distance is compared to a target value for the change in distance between the upper and lower substrate holders, and the difference is recorded for each sensor in order to record specific correction values ​​for the optical fiber distance sensor and intensity curve. In the eleventh method step, calibration using the replaced substrate is iteratively recorded as a series of measurements in order to create a knowledge memory and / or database of correction values ​​for the optical fiber distance sensor. A curve approximating pairs of points of intensity values ​​at a given distance is called an intensity curve. In particular, since the intensity curve can be approximated using empirical formulas, the expected intensity can be interpolated for a given distance between the substrate holders in the bonding apparatus. Conversely, for each sensor, the distance is determined from the measured intensity.

[0071] Changing the substrate for calibration means that a statistically significant number of measurements are performed using different substrates. Therefore, variations in substrate thickness, material reflectivity, material differences, or variations due to different positioning on the substrate holder are recorded and used as correction values ​​to affect the junction wave measurement and, consequently, the junction wave. In this way, apparatus-specific and substrate-specific correction values ​​are determined.

[0072] This makes it easier to spatially and temporally detect all possible distances between the upper and lower substrate holders during fusion bonding within the operating range of the optical fiber distance sensor.

[0073] In particular, the bonding process is affected by state determination, and the bonding wave velocity is controlled. For this purpose, deformation elements and / or fixed elements are deliberately controlled so that a portion of the second substrate is released or held.

[0074] Preferably, knowledge from machine learning algorithms and / or experience stored in a database are provided to be used to influence the joining process in response to state decisions. To utilize the measured state decisions determined across multiple joining processes, the recorded state decisions, along with the results of the joining processes, are provided to a neural network as a test set. The neural network uses the test set to develop new strategies for controlling the joining process for a particular state decision, and preferably applies them to equivalent state decisions in subsequent joining processes. This makes it possible to use the method for further optimization of the joining process.

[0075] Preferably, the sensor element is provided to include at least one optical fiber element, preferably an optical fiber distance sensor. Most preferably, at least one optical fiber element is incorporated so that it can be displaced, and in particular so that it can be pivoted, within the device.

[0076] The apparatus for joining substrates includes, in particular, the following functional components and / or modules: - Substrate holder: A substrate holder is used to hold a substrate. In particular, at least one substrate holder equipped with sensors and actuators is used for this purpose. Furthermore, an improved device is understood to have a substrate holder equipped with at least one, preferably more than 30 sensors and more than 30 actuators for influencing the junction wave. In the most preferred embodiment of the device, the substrate holder has more than 50 sensors and more than 50 actuators.

[0077] Preferably, the bonding apparatus includes at least one optical fiber distance sensor as a sensor, and preferably, as many vacuum zones as the number of optical fiber distance sensors are independently switchable. In particular, the optical fiber distance sensor may be adjustably incorporated into a substrate holder, especially an upper substrate holder.

[0078] In particular, the substrate holder has individually switchable, fluidly separated zones, especially vacuum zones, each of which is assigned to an optical fiber distance sensor, and the optical fiber distance sensor is specifically integrated into the corresponding vacuum zone. As a result, the measurement of substrate fixation and vacuum control are coupled to each other on the shortest control loop, and the measurement of substrate deformation is performed at the location where the substrate deforms due to the action of the vacuum zone.

[0079] The substrate holder has a fastener. The fastener is used to hold the substrate in place. The fastener is, 1. Mechanical fasteners, especially 1.1 Clamp 2. Vacuum fasteners, especially 2.1 Individually controllable vacuum channels 2.2 Mutually coupled vacuum channels 3. Electrical fixtures, especially 3.1 Electrostatic Fixation Devices 4. Magnetic fixture 5. Adhesive fasteners in particular 6. Gel pack fixation device 7. Fixtures having adhesive, which may be fixtures having a controllable surface.

[0080] In particular, the fastener is electronically controllable. A preferred form of fastener is a vacuum fastener. A vacuum fastener preferably includes a plurality of vacuum channels opening from the surface of the substrate holder. The plurality of vacuum channels are preferably individually controllable. In more technically feasible applications, the plurality of vacuum channels may be coupled to form a vacuum channel segment that is individually controllable and therefore can be individually evacuated or injected. However, each vacuum segment is independent of the other vacuum segments. This makes it possible to configure individually controllable vacuum segments. The vacuum segments are preferably designed in a ring shape. However, the shape of the vacuum zone can be arbitrary. This makes it possible to target and fix and / or release the substrate relative to the substrate holder.

[0081] The apparatus comprising the optical fiber distance sensor according to the present invention can be used, among other things, for the following possible applications, which are understood to be particularly independent inventions. - An apparatus comprising means for moving and / or aligning a substrate with an actuation element, and an actuator for generating a force to change the curvature of the substrate.

[0082] In one embodiment of the device, the moving means for holding the substrate can deform the substrate in a reproducible manner. - Moving means and / or alignment means for substrates such as coarse drive unit and / or fine drive unit. - Joining initialization means for fusion joining, in particular pins, fluid pressure means, in particular nozzles with gas overpressure, and / or combinations thereof -In the apparatus according to the present invention, the moving means and / or alignment means are preferably understood as a moving device comprising a drive system, a guide system, a fixing fixture, and a measuring system, thereby enabling the optical system and / or substrate to be moved, positioned, and aligned relative to each other.

[0083] Since the moving device can generate each movement as a combination of individual movements, the moving device may preferably include a high-speed coarse positioning device that does not meet accuracy requirements and a high-precision fine positioning device that operates with high accuracy.

[0084] Optical fiber distance sensors are particularly advantageous for use as measuring devices in bonding equipment, as optical fibers allow for a compact design, enabling the integration of high-density measuring devices within the substrate holder. Since the evaluation device and radiation source do not need to be directly placed on the substrate and / or substrate holder, the bonding equipment can be retrofitted. Another advantage is the ability to achieve higher data density compared to conventional measurement methods such as laser sensors or confocal sensors.

[0085] Furthermore, apparatus according to an advantageous embodiment may include a supply system and auxiliary and / or supplementary systems (compressed air, vacuum, power, liquids such as hydraulics, coolants, heating agents, means and / or apparatus for temperature stabilization, electromagnetic shielding, ionizers and / or deionizers, electrostatic precipitators).

[0086] Furthermore, the apparatus according to the present invention includes a frame, panels, and active or passive subsystems for vibration suppression, damping, or absorption. The frame can be understood in particular as a member made of natural hard stone or mineral casting material or spheroidal graphite cast iron or hydraulic joint concrete, and is configured in particular with vibration damping and / or vibration isolation and / or vibration damping.

[0087] Furthermore, the apparatus according to the present invention preferably comprises at least one measuring system having a measuring unit for each moving axis, the measuring system may be designed in particular as a displacement measuring system and / or an angle measuring system. Furthermore, the apparatus comprises at least one measuring system, preferably having a unit for measuring radiation intensity, in particular radiation intensity for curing embossing compounds.

[0088] Furthermore, the apparatus includes at least one measuring system for observing and / or confirming the alignment markers of the first and second substrates. Furthermore, the apparatus includes at least one pressure (in particular, vacuum and / or overpressure) measuring and control system that measures, detects, and controls the pressure on / inside the substrate during bonding.

[0089] Furthermore, the apparatus according to the present invention includes at least one measuring system for observing the alignment of substrates. These are provided, for example, in addition to measuring distance by back-reflected light.

[0090] Both tactile, i.e., contact-based, and non-tactile measurement methods can be used. The measurement standard, i.e., the unit of measurement, may exist as a physical object, such as a scale, or it may exist implicitly in the measurement method, such as the wavelength of radiation used.

[0091] At least one measuring system may be selected and used to achieve alignment accuracy before joining. The measuring system performs a measuring method. In particular, • Inducement methods and / or • Capacitive methods, and / or • Resistance method, and / or • Comparison method, particularly optical image recognition method, detection of position markers and / or QR code (registered trademark), and / or • Incremental or absolute methods (in particular using a glass reference as a scale, or an interferometer, especially a laser interferometer, or a magnetic reference), and / or • Driving time measurement methods (Doppler method, time-of-flight method) or other time recording methods, and / or • Triangulation, especially laser triangulation • Autofocus method, and / or • Methods for measuring the intensity of optical fiber distance meters, etc. It can be used.

[0092] For example, by combining and / or referencing and / or correlating the measured values, the position of one alignment marker can be estimated from the measurement of another alignment marker. In particular, the position of the substrate is calculated based on the position value of the substrate holder and the position value of the detected alignment marker, and corrected accordingly.

[0093] In a first embodiment of the present invention, optical pattern recognition by a camera system can be used to determine the position, particularly the 3D position at one, two, three, or any number of points, using a unique criterion for position and height. The pattern is continuously recorded in a real-time system, particularly during substrate alignment. The listed measurement methods can also be used to determine the position.

[0094] Preferably, moving devices not used for fine adjustment are designed, particularly as part of a robotic system, preferably equipped with incremental encoders. The precision of these moving devices for auxiliary movement is separate from the precision required for substrate alignment, and as a result, auxiliary movement is performed with a low repeatability of less than 1 mm, more preferably less than 500 micrometers, and most preferably less than 150 micrometers.

[0095] The accuracy of the alignment device is preferably less than 200 nm, more preferably less than 100 nm, even more preferably less than 50 nm, most preferably less than 20 nm, optimally less than 10 nm, and ideally less than 1 nm.

[0096] In a preferred embodiment of the apparatus, the alignment accuracy error of the apparatus is 20% of the maximum allowable alignment error, more preferably 10%, and ideally 1%.

[0097] The method is preferably prepared as a recipe and executed in a machine-readable format. A recipe is an optimized set of values ​​for functionally or process-related parameters. The use of a recipe makes it possible to ensure the reproducibility of the manufacturing process.

[0098] In one embodiment of the bonding process, the lower substrate is fused to the upper substrate in the following order, and in particular in the following steps. In the first method step, the lower substrate is placed on the lower substrate holder and measured by at least one optical fiber distance sensor installed in the upper substrate holder.

[0099] In the second method step, the lower substrate is mounted to the lower substrate holder, particularly using a vacuum zone, and the mounting condition is measured as additional control by at least one optical fiber distance sensor, thereby preferably minimizing local deformation of the lower substrate.

[0100] In the third method step, the upper substrate is loaded into the bonding apparatus and measured in a free state by at least one optical fiber distance sensor to detect and correct any deformation and / or critical strain of the upper substrate.

[0101] In the fourth method step, the upper substrate is mounted to the upper substrate holder, particularly using a vacuum zone, and measured by at least one optical fiber distance sensor. The controlled mounting of the upper substrate minimizes and preferably eliminates unwanted strain and / or deformation of the upper substrate.

[0102] In the fifth method step, the substrates are aligned, in particular using alignment marks. In the sixth method step, fusion bonding is initiated by bringing the upper and lower substrates into contact. Fusion bonding can be initiated, in particular, using bonding pins. The start of bonding wave propagation is observed by at least one optical fiber distance sensor, which allows the bonding wave to propagate in a controlled manner.

[0103] In the seventh method step, the propagation of the junction wave is observed by at least one optical fiber sensor provided in the upper substrate holder. The distance between the back surface of the upper substrate and the upper substrate holder is recorded and / or stored as a function of time and / or supplied for the control of the junction wave, in particular for vacuum zone control, and / or visualized, and / or processed, and / or statistically evaluated.

[0104] In the eighth method step, the propagation of the bonding wave is influenced, particularly in real time in the seventh method step, by controlling the vacuum level of at least one vacuum zone of the substrate holder, thereby minimizing strain during bonding.

[0105] In the ninth method step, the fusion bonding of the substrate stack is completed and the upper substrate holder is separated from the upper substrate. This method step may optionally be performed in parallel with the seventh and / or eighth method step.

[0106] In the tenth method step, the pre-bonded substrate stack is removed from the bonding apparatus and provided to the quality control department in particular. Any features disclosed in this specification and / or in the description of the following drawings as features of an apparatus shall be deemed to be disclosed as features of a method, and vice versa. All numerical values ​​and relationships in this disclosure (parallelism, congruence, orthogonality, flatness, etc.) are used as terms for quantities related to tolerances, and therefore, unless tolerances are explicitly stated, tolerances for non-congruence of length or angular dimensions under ISO 2768 and quasi-standards related to the semiconductor industry (flatness, wavyness, deflection, particle adhesion, etc.) shall apply.

[0107] Another object of the present invention is a substrate holder for the apparatus according to the present invention, wherein a sensor element is incorporated into the substrate holder. All the advantages and characteristics described with respect to the apparatus can also be applied to the substrate holder, and vice versa.

[0108] Another object of the present invention is a sensor element for incorporation into the apparatus or substrate holder according to the present invention. All the advantages and characteristics described with respect to the apparatus can be similarly applied to the substrate holder and sensor element, and vice versa. In particular, the sensor element is provided to be usable for upgrading existing apparatus. For example, the sensor element is sized to be inserted into a recess that was originally intended or is intended to be an opening for a vacuum opening or a deformation element. As a result, it is sufficient to simply position and secure the sensor element in the corresponding recess.

[0109] Further advantages, features, and details of the present invention will become apparent from the following description and drawings of preferred embodiments. [Brief explanation of the drawing]

[0110] [Figure 1] This is a schematic diagram of a fusion bonding apparatus equipped with an integrated optical fiber distance sensor. [Figure 2] This is a schematic cross-sectional view of a substrate holder equipped with an integrated optical fiber sensor. [Modes for carrying out the invention]

[0111] In the drawings, the advantages and features of the present invention are indicated by reference numerals that identify them according to embodiments of the invention, and components or features having the same or equivalent function are given the same reference numerals.

[0112] The drawings should be understood as schematic diagrams, not as indicators of dimensions or scale. They are used for explanatory purposes and, in some cases, may be exaggerated to show the relationships between components.

[0113] Figure 1 shows a part of the fusion bonding apparatus 1. The bonding apparatus 1 includes a frame 8, on which an optical detection means 3 for the lower substrate 11 is mounted on a movable frame 2 equipped with a moving device 4. In particular, an optical detection means 7 for detecting alignment marks on the upper substrate (not shown) is positioned on the same optical axis as the optical detection means 3. The movable frame 5 and moving device 6 allow the optical detection means 7 to be focused on the alignment marks.

[0114] The lower substrate holder 9 can hold the lower substrate 11. The vacuum segments and vacuum channels of the substrate holder 9 are not shown. The lower substrate holder's moving device 10 performs loading and unloading, as well as moving the substrate as necessary for alignment.

[0115] The upper substrate holder 12 can hold an upper substrate (not shown). The vacuum segments and vacuum channels of the upper substrate holder 12 are not shown. A moving device 13 of the upper substrate holder may be used to perform the substrate movements necessary for loading, unloading, and adjustment. The bonding pins 14 shown schematically are for initiating fusion bonding after the substrate approaches the bonding wave. Optical fiber distance sensors 15 having two virtually overlapping beams 16 are shown, which are used to measure distance a 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. Other optical fiber distance sensors, radiation sources, and evaluation units are not shown. In particular, those skilled in the art will understand that a sensor element formed as a fiber is a component whose fiber end is provided for receiving light or signals. These signals are then sent to a common evaluation device, which is a relatively large component located away from the sensor element. Preferably, signals from multiple fibers, each having multiple fiber ends arranged adjacent to one another, are aggregated and evaluated together in a common evaluation device.

[0116] Figure 2 shows a top view of a portion of the upper substrate holder 12', with the functional surface schematically indicated. The two fibers of the optical fiber distance sensor are indicated as 15'. The vacuum nozzle 17 is connected to the vacuum control unit and fluid, thereby allowing adjustment of the applied vacuum. The schematically shown seal lip 18 defines the illustrated vacuum zone. Another similar vacuum zone with identical elements is shown without reference numerals. [Explanation of Symbols]

[0117] 1... Apparatus for joining circuit boards 2…Movable frame of the upper optical detection means 3…Upper optical detection means 4. Moving device for the upper optical detection means 5…Movable frame of the lower optical detection means 6. Moving device for the lower optical detection means 7…Lower optical detection means 8...frames 9…Lower circuit board holder 10…Moving device for the lower substrate holder 11...Lower board 12,12'... Upper substrate holder 13…Moving device for the upper substrate holder 14…Connecting pin 15,15'…fiber 16… Iconic measurement beam of an optical fiber distance sensor 17…Vacuum nozzle 18… Vacuum seal, sealing lip

Claims

1. A method for joining a first substrate to a second substrate (10), wherein the first substrate comprises a primary section and the second substrate (10) comprises a secondary section. When the first substrate is bonded to the second substrate (10), the bonding wave propagating along the bonding direction is - A first subsection to which the first substrate and the second substrate (10) are joined, - Formed between the first substrate and the second substrate (10) and the second subsection which has not yet been joined, During bonding, the portion of the second substrate (10) in the second subsection is preferably offset at least temporarily in the height direction from the portion of the second substrate (10) in the first subsection in a direction perpendicular to the main extending surface. A method for determining the state of an object, wherein, before and / or during joining, light is directed towards the surface of the object and reflected, the light reflected by the surface is measured by the sensor element (15) for determining the distance between the sensor element (15) and the surface, and the distance (a) between the sensor element (15) and the surface is determined.

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

3. The method according to claim 1 or 2, wherein the distance set between the sensor element (15) and the surface of the object is 10 μm to 1000 μm, more preferably 10 μm to 500 μm, and most preferably 10 μm to 200 μm.

4. The method according to any one of claims 1 to 3, wherein for spatial resolution, an array of multiple sensor elements (15), preferably more than 10 sensor elements (15), more preferably more than 30 sensor elements, and more preferably more than 50 sensor elements (15) is used, and / or at least one sensor element (15) is moved.

5. The method according to any one of claims 1 to 4, wherein the object is the first substrate or the second substrate (10).

6. The method according to claim 5, wherein multiple state determinations are detected during bonding to determine changes in state detected over time, and in particular, the propagation of the bonding wave on the second substrate (10) is detected.

7. The method according to any one of claims 1 to 6, wherein the junction is affected depending on the state determination, and in particular the junction wave velocity is controlled.

8. The method according to any one of claims 1 to 7, wherein the state determination is used to minimize the distance set between the first substrate and the second substrate (10) before bonding.

9. The method according to any one of claims 5 to 8, wherein the alignment of the second substrate (10) and / or the first substrate is determined while it is being received by the substrate holders (10, 12) associated with the state determination and / or after it has been received.

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

11. In particular, an apparatus (1) for joining a first substrate to a second substrate (10) according to the method of any one of claims 1 to 10, wherein the first substrate comprises a primary section and the second substrate (10) comprises a secondary section, and the apparatus, when joining the first substrate to the second substrate (10), has a bonding wave that propagates along the bonding direction. - A first subsection to which the first substrate and the second substrate (10) are joined, - In particular, in order to detect the propagation of the junction wave of the second substrate (10), it is formed between the first substrate and the second substrate and the second subsection which are not yet joined, The portion of the second substrate (10) in the second subsection is offset in the height direction from the portion of the second substrate (10) in the first subsection in a direction perpendicular to the main extending surface. The apparatus (1) is equipped with a sensor element (15), and for determining the state of the object, the apparatus (1) is designed such that, for determining the state of the object, light is directed towards the surface of the object and reflected before and / or during bonding, the light reflected by the surface is measured by the sensor element (15) for determining the distance between the sensor element (15) and the surface, and the distance (a) between the sensor element (15) and the surface is determined.

12. The apparatus (1) according to claim 11, wherein the sensor element (15) comprises at least one optical fiber element, preferably an optical fiber distance sensor, preferably a plurality of sensor elements (15), preferably more than 10 sensor elements (15), more preferably more than 30 sensor elements, more preferably more than 50 sensor elements (15), and / or an array of at least one sensor element (15) is used for spatial resolution.

13. The apparatus (1) according to claim 12, wherein the sensor element (15) has a fiber end and a signal transmission unit, and the sensor element (15) is designed such that the fiber end is provided for signal reception and the signal transmission unit is provided for signal transmission to evaluation devices arranged at intervals.

14. A substrate holder (12) for the apparatus according to any one of claims 10 to 13, wherein the sensor element (15), in particular the fiber end of the sensor element, is incorporated into the substrate holder (12).

15. A sensor element (15) for incorporation into the apparatus (1) according to any one of claims 1 to 13 or the substrate holder (12) according to claim 14.

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