Patent Application
20240036345
The invention relates to a method for the optical contact bonding of (two or more) components, comprising: placing a first surface of a first component onto a second surface of a second component so as to form an air film, and pressing the first surface of the first component against the second surface of the second component for the optical contact bonding of the first component to the second component. The invention also relates to an apparatus for the optical contact bonding of components which is suitable, in particular, for carrying out the method for the optical contact bonding of components.
Optical contact bonding is a connection of two materials in which the surfaces which bear against one another are held only by molecular forces of attraction, that is to say without a joining substance such as an adhesive, such that the connection can be partially or completely released (for example under the influence of moisture or a wedge effect). Optical contact bonding can be used with various materials, e.g. with ceramic materials or with glass materials.
Optical contact bonding is typically effected manually, the second component being oriented horizontally or abutting against a horizontally oriented support surface. The first surface of the first component is first of all carefully placed onto the surface of the second component and “floats” on an air film on the surface of the second component. A prerequisite for the formation of the air film is that the two surfaces have substantially the same geometry and are sufficiently smooth.
The weight force of the first component is generally not sufficient to displace the air film and trigger the actual optical contact bonding process in the case of such an areal abutment. Manual pressing of the first surface of the first component against the second surface of the second component therefore has the effect of displacing the air film between the surfaces, such that the two surfaces touch and the actual optical contact bonding process takes place, in which the two surfaces are connected to one another by molecular forces of attraction.
For optical contact bonding, the surfaces not only have to be very smoothly polished (flatness and surface imperfection or surface roughness typically in the range of 50-200 nm), but also have to be free from dust or particles, grease or hydrocarbons or any other soiling. The surfaces of the components are therefore typically cleaned prior to the optical contact bonding. Unevennesses and particle contamination on the surfaces to be optically contact bonded can result in the two components not being able to be brought into sufficiently close contact with one another in order for attracting interactions to form between the surfaces. However, in optical contact bonding there is the risk in particular—but not only—during the horizontal handling of the components that particles trickle onto the surface of the second component and result in inclusions, what are known as voids, after the optical contact bonding. These voids are flaws which weaken the connection and—if they occur at the wrong location—can result in the component part composed of the two components being rejected.
Optical contact bonding is an established process in precision optics and is utilized to connect components in the form of lenses. The components which are optically contact bonded to one another may alternatively form—possibly with further components which are fastened thereto—composite structures for lithography. Such a composite structure may form a holding apparatus for a wafer or a mirror for reflection of EUV radiation, as is described, for example, in WO2013/021007 A1. There are also areas of application for optical contact bonding in the semiconductor industry, in which a partially automated positioning of the components is effected and various process auxiliaries are used for the actual optical contact bonding operation.
U.S. Pat. No. 6,814,833B2 describes a method for the direct bonding of silicon-containing components, in which functional groups are generated on the surfaces to be connected. For the generation of the functional groups, the surfaces are brought into contact with a solution having a high pH, typically between 8 and 13.
US 2003/0079503 A1 describes a method for the direct bonding of glass components for a subsequent glass drawing process. For the direct bonding, the components can be brought into contact with an acid or with a solution having a pH greater than 8.
The article “Wafer direct bonding: tailoring adhesion between brittle materials”, A. Plöβl, G. Kräuter, Materials Science & Engineering R 25 (1-2), p 1-88 (1999) describes, inter alia, methods for changing the surface chemistry for the adaptation of bonding properties.
Different methods for the direct bonding of wafers, for example a plasma-activated low-temperature bonding method, are also described in the dissertation “Direct wafer bonding for MEMS and microelectronics”, Tommi Suni, VTT Publications 609.
One object of the invention is to provide a method and an apparatus for the optical contact bonding of components, the risk of inclusions between the surfaces being reduced in said method and apparatus.
According to one formulation, this object is achieved with a method of the type mentioned in the introduction, in which the step of placing the first component and preferably the step of pressing the first component is carried out by a robot.
The inventor has recognized that if the optical contact bonding is carried out manually, the risk of voids or inclusions forming during the optical contact bonding is increased considerably even when the optical contact bonding is carried out in a clean room, since humans represent the greatest source of particles in the clean room. The invention therefore proposes carrying out at least the placing step, possibly also the pressing step, with the aid of a robot. The robot holds the first component and carries out the placing step, and possibly the pressing step, in an automated manner, without a human needing to be present in the vicinity of the components for this purpose.
Tests have shown that the placing of the first surface of the first component onto the second surface of the second component so as to form an air gap is possible with the aid of a robot, without the optical contact bonding being triggered directly in this step by a force effect or by the pressing of the first surface of the first component against the second surface of the second component. However, in principle, it is also possible for the placing and pressing steps to be performed with the aid of the robot simultaneously instead of successively. In this case, during the placing with the aid of the robot, a force which is great enough to trigger the optical contact bonding operation is exerted on the second component. In both cases, it has been observed that, after the optical contact bonding, the interconnected components did not exhibit any inclusions or bubbles or the number of inclusions or bubbles was reduced considerably.
In principle, it is possible for only the placing step to be carried out with the aid of the robot. In this case, the pressing step is effected manually, when the two surfaces areally abut against one another. Since the air film formed during the placing operation has a thickness in the micrometer range, the risk of particles being deposited between the two surfaces is low when said surfaces are manually pressed against one another in the abutting state. However, such a partially automated optical contact bonding operation with a manual pressing operation is dependent on the experience of the operator and is therefore reproducible only to a limited extent. The manual activation or the manual pressing of the components results in undefined surface states and typically does not enable any qualification of the surfaces and of the optical contact bonding operation itself. If the robot performs the pressing operation, it generates a pressing force or a corresponding torque which is strong enough to initiate the optical contact bonding.
Furthermore, in the method according to the invention a laminar gas flow is generated between the first surface of the first component and the second surface of the second component with a ventilation device.
In one variant, the second component is oriented at an angle with respect to a horizontal plane, in particular vertically (i.e. at an angle of 90° with respect to the horizontal plane), during the placing and preferably during the pressing of the first component. As has been described further above, when the second component is oriented horizontally there is the risk of particles settling under the action of gravity on the second surface of the second component. The orientation of the second component at an angle with respect to the horizontal, in particular in a vertical orientation, reduces the risk of particles being deposited on the second surface of the second component. In the case of a planar second surface, the angle between the second component and a horizontal plane is measured between the horizontal plane and the second surface. If the second surface is not planar, the angle is measured with respect to a reference surface of the second component. Typically, the reference surface is a planar surface of the second component with which said second component would abut against a support surface in the horizontal orientation.
In a further variant, the laminar gas flow is generated between the first surface of the first component and the second surface of the second component with the ventilation device such that it is preferably oriented at an angle with respect to a horizontal plane, in particular vertically, or is oriented horizontally or substantially horizontally (i.e. at an angle of +/−20° with respect to the horizontal plane). If the gas flow is oriented at an angle with respect to a horizontal plane, in particular vertically, the flow direction of the gas flow usually runs from top to bottom, i.e. in the direction of gravity or substantially in the direction of gravity. This variant is expedient in particular when the second component is oriented at an angle with respect to the horizontal plane, in particular vertically, since in this case particles which pass between the two surfaces can be entrained by the gas flow substantially in the direction of gravity. Even if the second component is oriented (substantially) horizontally during the optical contact bonding, it is favorable for a laminar gas flow to be generated between the surfaces of the two components. In this case, the laminar gas flow may be oriented in particular substantially in a horizontal direction.
For the generation of the gas flow, use may be made of a ventilation device, for example what is known as a fan filter unit (FFU), as is used in clean rooms. Such a fan filter unit comprises a fan and a filter, said fan drawing in air from above and blowing a gas flow in the form of a laminar air flow through the filter into the clean room, said air flow typically being oriented in a vertical direction, i.e. in the direction of gravity. For the generation of a gas flow which runs (substantially) in the horizontal direction with the aid of a fan filter unit, a portion of the gas that has passed through the filter can be branched off. However, it is also possible in this case to use an independent ventilation device, which provides (cleaned or filtered) compressed air, in order to generate a laminar air flow which is blown in between the surfaces.
In a further variant, prior to the (areal) placing operation, a subregion of the first surface of the first component, said subregion being formed in particular at a lateral edge of the first surface, is brought into contact with the second surface of the second component. If when the second component is approached the robot hand or the gripping device which holds the first component is not oriented with its longitudinal axis parallel to the normal direction to the second surface, but rather obliquely or at an angle, only a subregion of the first surface strikes against the second surface during the approach. Here, the first surface typically contacts the second surface only at its lateral edge, wherein the force exerted upon first contact between the first surface and the second surface is generally selected to be so low that optical contact bonding does not occur. The force exerted on the second component in the subregion by the robot or by the first component should therefore generally not exceed the weight force and should lie in the order of magnitude of e.g. about 10 N.
The subregion with which the first component contacts the second component should be positioned on the second surface such that the first component no longer needs to be displaced relative to the second component during the subsequent areal placing operation. Ideally, the subregion at the lateral edge of the first surface contacts a subregion at the lateral edge of the second surface.
In a further variant, the contact between the subregion of the first surface and the second surface is detected, specifically preferably on the basis of a torque exerted on the robot by the second component. The robot, more precisely a robot hand or gripping device of the robot, holds the first component during the step of placing onto the second component, wherein a longitudinal axis of the gripping device, for example of the robot hand, about which the latter is rotatable, is typically located approximately in the center of the first surface. If during the movement of the robot or the gripping device the subregion, which is laterally offset with respect to the longitudinal axis or central axis of the robot, of the first surface of the first component comes into contact with the second surface, a torque is exerted on the robot upon contact with the second surface. This torque can be measured with the aid of at least one torque sensor which is mounted on the robot or on at least one joint of the robot. However, the first contact between the subregion of the first surface and the second surface can also be detected in another way, e.g. optically or with a contact sensor based on a different measuring principle.
In a further variant, the first surface of the first component and the second surface of the second component are oriented at a predefined angle with respect to one another during the contacting of the subregion. The predefined angle may be selected to be relatively large, e.g. more than about 10° or 15°. If during the contacting in the subregion the first component is oriented at a large angle relative to the second component, the risk of unintentional optical contact bonding can be minimized. In addition, the first component can be rotated in a controlled manner for the areal placing onto the second component, as described below.
In a further variant, the first component is rotated about the abutting subregion until the first surface of the first component abuts areally against the second surface of the second component. As has been described further above, during the areal placing operation, an air film is formed between the first surface and the second surface if an excessive contact pressure is not exerted on the second component. The rotation of the first component about the subregion makes it possible to effect the placing with a controlled (rotational) movement, ideally without an additional translational movement of the first component being required for this purpose. The robot generally allows small compensating movements of the first component during the rotational movement, in order to reduce or compensate for excessive forces or torques.
In a further variant, the areal abutment of the first surface of the first component against the second surface of the second component is detected, specifically preferably on the basis of a torque exerted on the robot by the second component, in particular on the basis of a minimization of the torque exerted on the robot by the second component. If the first surface of the first component has been oriented as desired relative to the second surface of the second component by the robot, the torque exerted on the robot by the second component is typically minimal. As has been described further above, the detection of the areal abutment is not limited to the detection of a torque, but rather may possibly also be effected in another manner, for example by another type of contact sensor or by an optical sensor.
In a further variant, the method comprises: detecting an interference fringe pattern of the air film, which is formed between the two surfaces areally abutting against one another, wherein the detecting of the interference fringe pattern is preferably effected through the second component. It is possibly also possible for the interference fringe pattern to have already been detected during the placing, if the air film has already partially formed. The interference fringe pattern is generated because the two surfaces are not oriented completely parallel to one another.
The detecting of the interference fringe pattern can be used, for example, to identify the optical contact bonding operation or the end of the optical contact bonding operation: if the two components have been optically contact bonded to one another, the interference fringe pattern disappears, since the air film between the two surfaces has been displaced. In this case, the robot can let go of the first component, since it is connected to the second component. If the pressing operation has been carried out by the robot and an interference fringe pattern is still apparent e.g. in a subregion of the two surfaces after the pressing operation, this means that the optical contact bonding was not successful. In this case, the two surfaces which are partially optically contact bonded to one another can be released from one another again, for example by virtue of the robot moving the first component away from the second component again and for example generating a wedge effect. Further measures may also be taken to release the two components from one another again.
In a further variant, a pressing position, at which the first surface is pressed against the second surface, is defined in dependence on the detected interference fringe pattern, in particular in dependence on a direction of extent of the interference fringe pattern. Generally, during the pressing operation, a contact pressure is not applied to the entire first surface, rather a pressing position is selected at which the air film is intended to first be displaced. In this case, the optical contact bonding process is effected proceeding from the pressing position in the manner of a displacement wave, which propagates along the two surfaces and displaces the air film.
On the basis of the orientation of the interference fringes of the interference fringe pattern, it is possible to identify the direction in which the displacement wave of the air film propagates: the displacement wave generally propagates perpendicularly with respect to the direction of the interference fringes. It is therefore favorable for the pressing position to be selected in dependence on the orientation of the interference fringes of the interference fringe pattern. In principle, it is advantageous for the pressing position to be selected at the lateral edge of the first surface. Here, the pressing position is preferably selected to be that position at the lateral edge of the first surface at which the surface has its maximum extent in a direction perpendicular to the direction of extent of the interference fringes.
In a further variant, at least one, preferably a plurality of parallel-oriented, in particular trench-like depressions is/are formed on the first surface of the first component and/or on the second surface of the second component, wherein an orientation of the first component during the areal abutment is selected in dependence on the orientation of the interference fringe pattern relative to a longitudinal direction of the at least one depression.
If one or more depressions are formed in the first component and/or in the second component, the displacement wave of the air film, said wave being generated during the pressing operation, should preferably not propagate perpendicularly with respect to the longitudinal direction of the depression(s), since the displacement wave, and thus the optical contact bonding, may otherwise be stopped at the depression. The displacement wave should therefore be oriented at an angle which differs from 90° with respect to the depression or depressions. Such an orientation of the interference fringe pattern may possibly be achieved by suitable, slight movements of the first component with the aid of the robot.
A parallel orientation of the interference fringes of the interference fringe pattern with respect to the longitudinal direction of the trench-like depression(s) should therefore be avoided. It is particularly favorable for the direction of extent of the interference fringe pattern to be oriented perpendicularly with respect to the longitudinal direction of the at least one depression, i.e. at an angle of 90°. Angles which deviate by at least 30° from the longitudinal direction of the depression(s) have proven favorable for the direction of extent of the interference fringes.
The trench-like depressions may, for example, run substantially rectilinearly in the second component. The depressions are covered by the first component during the optical contact bonding, as a result of which channels are formed in the component part produced during the optical contact bonding. This component part may, for example, be a substrate for a reflective optical element, e.g. for a mirror. In this case, a reflective coating may be applied to the first component prior to or after the optical contact bonding. The reflective coating may be configured, for example, to reflect radiation in the EUV wavelength range or to reflect radiation in the VUV wavelength range. The second component may also comprise depressions for some other reason. If the component part produced during the optical contact bonding is a mirror, the contact surface formed during the optical contact bonding is typically located in the vicinity of the optical used surface of the mirror, to which used surface the reflective coating is applied. It is therefore particularly important in this case that the fewest possible and in particular no large defects occur along the contact surface.
It is also possible for only the first component to comprise depressions, which are covered by the second surface of the second component during the optical contact bonding, as a result of which channels are formed in the component part produced during the optical contact bonding. It is likewise possible for the first component and the second component to comprise depressions. In this case, the depressions in the first component have to be oriented in a suitable, generally parallel, manner with respect to the depressions in the second component during the optical contact bonding. In this case, it is also possible for the orientation of the interference fringe pattern relative to the depressions in the two components to be changed by a suitable orientation of the first component with the aid of small deflections.
It is not absolutely necessary for the first surface of the first component and the second surface of the second component to be of planar form. Rather, the two surfaces may be of complementary form, such that they fit together during the placing operation. By way of example, the first surface may be convexly curved and be placed onto a correspondingly concavely curved second surface, or vice versa.
The material of the first and/or of the second component may be glass, e.g. quartz glass, in particular titanium-doped quartz glass, such as is offered for example under the trade name ULE®, or some other glass. The material of the first and/or of the second component may alternatively be a glass ceramic or a ceramic, e.g. cordierite. Optical contact bonding is in principle also possible with materials other than those mentioned here.
A further aspect of the invention relates to an apparatus for the in particular fully automated optical contact bonding of components, in particular for carrying out the method for the optical contact bonding of components as described further above, comprising: a robot which is configured or programmed to place a first surface of a first component onto a second surface of a second component so as to form an air film, wherein the robot is preferably configured to press the first surface of the first component against the second surface of the second component, in order to optically contact bond the first component to the second component, and a holding device for holding the second component during the placing and during the pressing of the first component, and a ventilation device for generating a laminar gas flow between the first surface of the first component and the second surface of the second component.
For carrying out the placing step and possibly for carrying out the pressing step, the apparatus may comprise a control device which is configured or programmed to control the robot in order to carry out the above-described method or the variants of the above-described method which are carried out with the aid of the robot. The control device may be a suitable piece of hardware and/or software which is able to be programmed to generate commands for the robot and to transmit them to the robot, if the control device is not integrated into the robot.
The use of a robot affords the possibility of adapting the optical contact bonding process to individual components or component geometries. By way of example, a subregion of the first surface in which first contact with the second surface is established, joining movements such as the rotation or the rolling of the first component, the starting side of the optical contact bonding or the pressing position and the introduced forces may be changed without reconstruction being required. In order to achieve this, the robot should comprise at least one joint, generally two or more joints, in order to also be able to carry out a rotational movement in addition to a translational movement of the first component. The first component can be held by a robot hand or a gripping device of the robot arm, which is connected to the robot arm by way of a joint.
Instead of a robot arm, the robot may also comprise a gripping device with a plurality of clamping elements which are each connected to a, for example, telescopic linear unit, in order to clamp the first component at multiple locations which are typically located along the lateral periphery or edge of the first component. With the aid of the linear units, the robot can execute a translational movement of the first component. If the clamping devices are connected to the linear units by way of joints, a rotational movement of the first component can also be effected in addition to the translational movement if, during the movement of the component, the linear units are moved at different speeds or to different extents. Other configurations of the robot or of the kinematic system are also possible.
In one embodiment, the robot comprises at least one sensor, preferably at least one torque sensor, for detecting the areal abutment of the first surface of the first component against the second surface of the second component, and preferably for detecting first contact between a subregion of the first surface and the second surface. The detection can be effected with the aid of a force-torque or torque sensor, as is described further above in conjunction with the method. However, it is also possible for the areal abutment or the first contact between the first surface and the second surface to be detected with a different type of sensor.
In one embodiment, the holding device is configured to orient the second component at an angle with respect to a horizontal plane, in particular vertically. As has been described further above, a robot, which detects whether the first component has been placed, can be used to carry out the placing step and possibly the pressing step on a non-horizontally oriented second component. In particular if the second surface is oriented substantially vertically, it is possible to prevent particles from settling under the action of gravity on the second surface.
In a further embodiment, the apparatus comprises the ventilation device for generating the laminar gas flow between the first surface of the first component and the second surface of the second component, wherein the gas flow is preferably oriented at an angle with respect to a horizontal plane, in particular vertically, or horizontally or substantially horizontally (at an angle of +/−30° with respect to a horizontal plane). The ventilation device may, for example, be what is known as a fan filter unit (FFU), as is used in clean rooms. Such an FFU is typically installed in the region of a top of the apparatus and comprises a fan and a filter, said fan drawing in the air from above and blowing it through the filter into the space between the two surfaces. In this case, the laminar gas or air flow is typically oriented vertically, can pass through a mesh bottom of the apparatus and be deflected with the aid of a flow guiding device, for example with the aid of a flow guiding plate, in order to generate a circulating air flow. The laminar air flow between the two surfaces also makes it possible to considerably reduce the risk of particles being deposited and thus the occurrence of voids during the optical contact bonding.
In a further embodiment, the apparatus comprises a spatially resolving detector, for example a camera, for detecting an interference fringe pattern of the air film, which is formed between the two surfaces areally abutting against one another, wherein the spatially resolving detector is preferably configured to detect the interference fringe pattern through the second component. A camera may be sufficient for the detecting of the interference fringe pattern, but it is also possible for the interference fringe pattern to be detected mechanically with the aid of a white light interferometer or with the aid of another suitable measuring device.
In this case, the second component is transparent to the wavelength(s) detected by the detector during the detection of the interference fringe pattern. These wavelengths may lie, in particular, in the visible wavelength range. The apparatus may also comprise an evaluation device, in order to evaluate the interference fringe pattern and to determine a direction of extent of the interference fringes of the interference fringe pattern. As has been described further above in conjunction with the method, a pressing position can be defined on the basis of the direction of extent of the interference fringes with the aid of the control device. The control device may also be used to correct the orientation of the first component if the direction of extent of the interference fringes is oriented in an unfavorable manner in relation to a longitudinal direction of trench-like depressions formed in the second or possibly in the first component.
The apparatus may also comprise a loading device for the loading with first and/or second components. For this purpose, the loading device may, for example, comprise a loading table on which first and/or second components can be deposited. For the loading, the first/second components may abut against a transport support which is moved e.g. with the aid of a roller table or another suitable handling device into the access region of the robot, which performs the placing of the first component onto the second component. The robot or another suitable handling device may first pick up a second component, in order to position the latter on the holding device. The holding device may be configured to receive the second component in an automated manner and to hold it e.g. with the aid of a suitable holding or clamping device. After the second component has been positioned on the holding device, the robot can pick up a first component or the first component is mounted on the robot and placed, by way of the first surface, areally onto the second surface of the second component in the manner described further above. It is also possible for the robot or another handling device to grip the component part produced during the optical contact bonding and to deposit it in an automated manner at a desired location, possibly on an unloading device provided for this purpose or at a predefined deposition position.
If the apparatus comprises the loading device described further above for the two components and an unloading device in order to unload the component part produced during the optical contact bonding, the apparatus can be used for the fully automated optical contact bonding of the two components. In the fully automated optical contact bonding, no worker or operator is required, but rather all steps of the optical contact bonding process run in an autonomous and fully automated manner in the apparatus.
The (possibly fully automated) apparatus may comprise a mechanical ultrafine cleaning device, which provides quantifiably cleaner surfaces of the components for the subsequent optical contact bonding process. For this purpose, the ultrafine cleaning device may, for example, comprise a nozzle in order to subject the surfaces of the components to a blowing-off operation. It is favorable for the process times of the processes following the ultrafine cleaning, in particular the optical contact bonding process, to be planned in an automated manner and in as efficient as possible a manner in terms of time, such that contamination of the surfaces can be effectively inhibited until the optical contact bonding process has concluded.
The apparatus may additionally comprise an inspection device for pre-process control, in which the surfaces of the components are analyzed in order to check the result of the ultrafine cleaning and possibly repeat it if the result is not satisfactory. As an alternative or in addition, the apparatus may also comprise a (further) inspection device for post-process control, in which the component part formed during the optical contact bonding of the two components is checked for flaws or defects, in particular in the form of air bubbles (voids), which weaken the connection between the two components. The (further) inspection device may quantify and qualify the defects e.g. with regard to number, position, size and possibly defect type and save the corresponding information in a database. The (further) inspection device may comprise a microscope for the detection of the defects, in order to carry out a microscopic inspection of the defects in the plane or in the region of the contact surface in which the optical contact bonding has been effected.
It is possible, but not absolutely necessary, for the apparatus to comprise a central handling or transport device which transports the components and/or the component part, formed during the optical contact bonding, within the apparatus and picks up or deposits them/it at different locations or stations of the apparatus. The handling device may, for example, comprise a robot arm, which may perform the above-described placing and possibly pressing of the surface of the first component. However, it is also possible for the apparatus to comprise two (or possibly more) robots, one robot being used to place and possibly press the first component and the further robot forming the handling device or part of the handling device.
Further features and advantages of the invention will become apparent from the following description of exemplary embodiments of the invention, with reference to the figures of the drawing, which show details essential to the invention, and from the claims. The individual features can be implemented individually in their own right or collectively in any combination in a variant of the invention.
Exemplary embodiments are illustrated in the schematic drawing and are explained in the following description. In the figures:
In the following description of the drawings, identical reference signs are used for identical or functionally identical components.
The robot 4 comprises a gripping device in the form of a robot hand 6, which is connected to the rest of the robot 4 by way of a joint 7. Fastened to the robot hand 6 is the first component 2 which is intended to be optically contact bonded to the second component 3. The fastening or the holding of the first component can be effected with the aid of the robot hand 6.
The second component 3 is mounted on a holding device 8 vertically, i.e. at an angle α of 90°, relative to a horizontal plane X, Y, which corresponds to the support plane of the loading table 5. As a result of the vertical orientation of the second component 3, the accumulation of particles on a second surface 3a of the second component 3, said second surface being intended to be optically contact bonded to a first surface 2a of the first component 2, is reduced, since the particles are no longer able to abut against the vertically oriented second surface 3a.
In the case of the apparatus 1 shown in
The apparatus 1 also comprises a spatially resolving detector 14 in the form of a camera, which is mounted on a side of the second component 3 that faces away from the second surface 3a. The detector 14 allows the second surface 3a and also the first surface 2a to be observed through the second component 3. In the example shown, the second component 3, like the first component 2, is formed from titanium-doped quartz glass, more precisely from ULE®, which is transparent to visible wavelengths, thus making the observation through the second component 3 possible. However, the first component 2 and the second component 3 may also be formed from other materials.
In the example shown in
As can be seen in
In the example shown, the robot 4 is controlled during the optical contact bonding operation described below by a control device 16 which also controls the loading of the apparatus 1 with first and/or second components 2, 3 with a loading device 17. The control device 16 is also connected to the detector 14 in terms of signaling and comprises an evaluation device in order to evaluate the image captured by the detector 14.
The method sequence during the optical contact bonding is explained below with reference to
First of all, the robot 4 is used to move the first component 2 closer to the second component 3 until a subregion 18 of the first surface 2a of the first component 2 bears against the second surface 3a. The subregion 18 of the first surface 2a is formed at the lateral edge of the first surface 2, as can be seen in
The first contact between the first surface 2a and the second surface 3a in the subregion 18 can be detected on the basis of a torque M, which is exerted on the first component 2 by the second component 3 and on the robot 4, more precisely on the longitudinal axis 19 of the robot hand 6 or on the joint 7, by said first component. As can be seen in
On the basis of the detected torque M, which is a vector quantity, the control device 19 can identify which direction or along which axis of rotation D the first component 2 has to be rotated in order to close the angle R and to place the first component 2 areally on the second component 3. Here, it is not absolutely necessary to know the direction of the torque M. The axis of rotation D during the rotation of the first component 2 is located in the subregion 18 in which the first contact takes place, i.e. the first component 2 is rotated about the already abutting subregion 18 or the corresponding contour at the edge of the first surface 2a.
The areal abutment of the first surface 2a of the first component 2 against the second surface 3a of the second component 3 is also detected with the aid of the torque sensor 20 of the robot 4: The torque M exerted on the first component 2 by the second component 3 in the areally abutting position shown in
In the example shown, with the components 2, 3 areally abutting against one another, the optical contact bonding is triggered by virtue of the first surface 2a of the first component 2 being pressed against the second surface 3a of the second component 3 at a pressing position 24 which is formed at the circular, peripheral edge of the first surface 2a. The pressing position 24 is illustrated in
Also visible in
The direction of extent X of the interference fringes 23 is thus oriented perpendicularly with respect to the longitudinal direction Y of the trench-like depressions 15. This is favorable since a displacement wave, which displaces the air film 21 out of the intermediate space or out of the gap between the two surfaces 2a, 3a, propagates transversely with respect to the interference fringes 23, i.e. in the Y direction, as indicated by an arrow in
Both the pressing position 24 and the orientation of the first component 2 or of the first surface 2a relative to the second component 3 or to the second surface 3a are defined in dependence on the orientation of the interference fringe pattern 22, more precisely on the direction of extent X of the interference fringes 23 of the interference fringe pattern 22. Here, the orientation of the first component 2, more precisely of the first surface 2a, can be changed by small movements of the first component 2 with the aid of the robot 4 in such a way that the direction of extent X of the interference fringes 23 is oriented substantially perpendicularly with respect to the longitudinal direction Y of the trench-like depressions 15. This makes it possible for the displacement wave, which displaces the air film 21, to not impinge on the longitudinal side of one of the trench-like depressions 15, since in this case the displacement wave might be stopped at the trench-like depression 15. Such an orientation of the first component 2 is also possible if the trench-like depressions 15 are formed in the first component 2 instead of in the second component 3, or if both the first component 2 and the second component 3 comprise trench-like depressions 15.
Since the displacement wave propagates perpendicularly with respect to the interference fringes 23 of the interference fringe pattern 22, the pressing position 24 is selected at that position at the peripheral edge of the first surface 2a at which the surface 2a has its maximum extent perpendicularly with respect to the direction of extent X of the interference fringes 23. In the example shown in
The successful optical contact bonding of the two components 2, 3 can also be checked with the aid of the spatially resolving detector 14: if the optical contact bonding was successful, the interference fringe pattern 22 in the captured image should completely disappear. If this is not the case, the two components 2, 3 may possibly be released from one another again, if the robot 4 exerts a sufficiently great force on the components 2, 3. It is also possible for the step of placing the two components 2, 3 onto one another to be interrupted or restarted, e.g. if the torque M cannot be minimized as desired. In this case, it is for example possible for a different subregion 19, which establishes the first contact with the second surface 3a, of the first surface 2a to be selected, as a result of which the axis of rotation D about which the first component 2 is rotated changes.
The component part which is formed during the optical contact bonding of the two components 2, 3 and which, in the example shown, is a mirror or a substrate for a mirror can be unloaded with the aid of the robot 4. Here, the robot 4, more precisely the robot hand 6, can grip or hold the two components 2, 3. However, it is also possible for the robot 4 to grip the assembled component part only on the first component 2, if the connection formed during the optical contact bonding is stable enough.
With the aid of the joints 7a, 7b, . . . , it is possible to also implement a controlled rotational or tilting movement of the first component 2 in addition to a translational movement of the first component 2 by virtue of the linear units 25a, 25b, . . . being deflected to different extents. The linear units 25a, 25b, . . . or the clamping devices 26a, 26b, . . . mounted thereon may possibly be precisely positioned with the aid of piezo actuators.
In order to measure the torque M exerted on the first component 2 by the second component 3, a respective torque sensor 20a, 20b, . . . (force-torque sensor) is mounted on a respective joint 7a, 7b, . . . of the robot 4, of which only two torque sensors 20a,b are illustrated in
The optical contact bonding of the two components 2, 3 which is described further above can be followed, for example, by a tempering step, in which a permanent connection between the two components 2, 3 is established; however, this is not absolutely necessary.
During the fully automated optical contact bonding, the machine stations A to E are passed through successively. The first machine station A is an input station, at which the two components are introduced via an air lock into the interior space of the housing 13. It is for example possible to use a conveyor belt to transport the components into the interior space. The input station A of the apparatus 1 comprises an ultrafine cleaning installation, at which the surfaces of the components are clean. The ultrafine cleaning installation is configured to blow off particles deposited on the surfaces with the aid of compressed air. However, the ultrafine cleaning installation may also clean the surfaces in a different manner. The ultrafine cleaning of a respective component at the input station A can be effected without said component needing to be held by the handling device 27.
After the ultrafine cleaning has concluded, the respective component is transported with the aid of the handling device 27 to the second machine station B, at which an inspection device for automated pre-inspection of the respective component, more precisely of that surface of the component which is connected to the surface of the other component during the optical contact bonding process, is arranged. The inspection device may, for example, comprise a camera or the like, in order to inspect the respective surface. If it is determined during the inspection that the cleanliness of the surface is not sufficient for the subsequent optical contact bonding process, the component can be transported back to the ultrafine cleaning device at the input station A by the handling device 27 and the ultrafine cleaning can be repeated.
If the surface of the respective component has a sufficient surface quality, said component is transported by the handling device 27 to the third machine station C, at which an optical contact bonding module 28 for the optical contact bonding of the two components to one another is arranged, said module being described in more detail further below. During the optical contact bonding, a component part is formed from the two components, said component part being transported with the handling device 27 to a fourth machine station D, at which a further inspection device for post-inspection of the component part is arranged. For this purpose, the further inspection device may, for example, comprise a microscope which checks whether defects, e.g. inclusions in the form of air bubbles, were formed along a for example planar contact surface at which the two components 2, 3 were connected to one another during the optical contact bonding. The defects are quantified and qualified by the further inspection device with regard to number, position, size and possibly defect type. The information obtained during the inspection is stored by the further inspection device in a database which can be accessed by a machine operator located outside of the housing 13.
The component part assembled during the optical contact bonding is transported by the handling device 27 from the fourth machine station D to a fifth machine station E, which is an output station at which the component part is deposited and transported via an air lock out of the interior space of the housing 13.
The optical contact bonding module 28 also comprises a robot 4 which, like the robot 4 shown in
As can be seen in
As can also be seen in
As has been described further above in conjunction with
As has been described further above in conjunction with
There are various possibilities for the implementation of the optical contact bonding process, of which four possibilities are indicated in highly schematic form in
In the optical contact bonding process shown in
As has been described further above, the conclusion of the optical contact bonding process, in which the two components 2, 3 are completely connected to one another at a contact surface, can be detected on the basis of the disappearance of the interference fringe pattern 22, since in this case the air film between the two surfaces 2a, 3a has been completely displaced. If the interference fringe pattern 22 does not disappear, the optical contact bonding process can be terminated or the two components 2, 3 can be separated from one another again by the application of a counterforce.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2021 203 570.1 | Apr 2021 | DE | national |
This is a Continuation of International Application PCT/EP2022/059203, which has an international filing date of Apr. 7, 2022, and the disclosure of which is incorporated in its entirety into the present Continuation by reference. This Continuation also claims foreign priority under 35 U.S.C. § 119(a)-(d) to and also incorporates by reference, in its entirety, German Patent Application DE 10 2021 203 570.1 filed on Apr. 12, 2021.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2022/059203 | Apr 2022 | US |
| Child | 18485370 | US |
