Method and device for forming a structure on a workpiece

Abstract

The invention relates to a device and a method for forming a structure on a workpiece by means of machining radiation whilst the workpiece is moved by means of the transport device, correction data of the workpiece being detected by means of optical sensors. The correction data comprise motion data of the workpiece and / or position data of a structure produced on the workpiece by means of the machining radiation, and the deflection of the machining radiation is determined, in particular corrected, by means of a deflection unit in dependence on the correction data.

Description

[0001] Method and device for forming a structure on a workpiece

[0002] Description

[0003] When machining workpieces, it is known to form a structure on a workpiece using electromagnetic machining radiation. Forming the structure can include modifying the workpiece using the machining radiation and / or removing material, in particular ablating it, using the machining radiation.

[0004] Laser radiation is typically used as the processing radiation. This type of laser-assisted formation of a structure and workpiece is particularly used in the manufacture of photovoltaic solar cells and in printed circuit board production.

[0005] To achieve high throughput in production, it is known to process the workpiece using processing radiation while the workpiece is moved by the transport device. This allows for inline processing, in particular.

[0006] The transport of the workpiece by means of a transport device during the machining of the workpiece has the disadvantage that fluctuations in the transport speed and / or movements of the workpiece on the transport device, in particular rotations of the workpiece, lead to inaccuracies in the machining.

[0007] It is therefore known to detect an incoming edge of the workpiece using an optical sensor before machining with the processing radiation. Such a device is described in EP 2940740 A1.

[0008] The present invention is based on the object of providing a method and a device for forming a structure on a workpiece by means of processing radiation, which enables greater precision in the case of irregular transport of the workpiece on the transport device.

[0009] This object is achieved by a method for forming a structure on a workpiece by means of processing radiation according to claim 1 and a device for forming a structure on a workpiece by means of processing radiation according to claim 11. Advantageous embodiments of the method according to the invention can be found in claims 2 to 10 and of the device according to the invention in claims 12 to 15.

[0010] The method according to the invention is preferably designed for implementation by means of the device according to the invention, in particular a preferred embodiment thereof. The device according to the invention is preferably designed for implementation of the method according to the invention, in particular a preferred embodiment thereof.

[0011] The present invention is based on the recognition that, in order to avoid location deviations during the machining of a workpiece by means of machining radiation, it is essential to detect correction data of the workpiece by means of at least one optical sensor during the machining of the workpiece.

[0012] The method according to the invention for forming a structure on a workpiece by means of processing radiation comprises the following processing steps:

[0013] In method step A, the workpiece is placed on a transport device. In method step B, the workpiece is moved along a movement path by means of the transport device and processed by means of the processing radiation while the workpiece is moved by means of the transport device. The time of processing and, preferably, the location of the processing of the workpiece by means of the processing radiation is controlled by means of an optical deflection unit for the processing radiation controlled by the control device in order to form the structure. In the method according to the invention, processing thus takes place in a manner known per se during transport by means of the transport device, thus enabling high throughput and inline processing.The timing of the processing is controlled by a control device in order to achieve processing at the desired location on the surface of the workpiece. It is advantageous to additionally control an optical deflection unit for the processing radiation using the control device, so that the optical deflection unit can deflect the processing radiation to different locations on the workpiece and / or deflect the processing radiation such that the radiation is directed at a processing location for a predetermined period of time, thus moving at the transport speed of the workpiece in the reference system of the device.

[0014] It is essential that, in method step B, during the processing of the workpiece using the processing radiation, correction data of the workpiece are acquired by at least one optical sensor. The correction data comprise movement data of the workpiece and / or position data of a structure created on the workpiece using the processing radiation. Depending on the correction data, the control device determines, in particular corrects, the time of processing and / or the deflection of the processing radiation using the deflection unit.

[0015] The transport of the workpiece by means of the transport device harbors various sources of error, which lead to inaccuracies and, in particular, location deviations during processing of the workpiece using the processing radiation: Even modern transport devices exhibit fluctuations in transport speed, so that estimates of the workpiece trajectory based on a typical constant transport speed can be inaccurate. Systems that measure the transport speed on the transport means, such as a conveyor belt of the transport device, also exhibit errors, as slippage between the measuring system and the conveyor belt or even a change in the length of the conveyor belt itself can occur. In addition, a change in the position of the workpiece on the transport device and relative to the transport means, for example relative to a conveyor belt, can occur, in particular due to shocks and vibrations.The method according to the invention enables a correction of such deviations since the correction data of the workpiece itself are recorded during the machining of the workpiece.

[0016] It is within the scope of the invention that the correction data include movement data of the workpiece. The movement data is used to determine the change in position of the workpiece and thus its position during machining. The acquisition of movement data is possible precisely and cost-effectively using optical sensors, as explained in more detail below.

[0017] It is also within the scope of the invention for the correction data to include position data of a structure created on the workpiece by means of the processing radiation. This provides the advantage that structure positions, in particular distances between subregions of a structure or distances between two separate structures formed by the processing radiation, can be compared with specified values, and corresponding corrections for the deflection of the processing radiation can be calculated using the optical deflection unit in order to avoid deviations during further processing.

[0018] It is also within the scope of the invention to record both movement data of the workpiece and position data of a structure produced on the workpiece by means of the processing radiation and to use them for the deflection of the processing radiation by means of the deflection unit.

[0019] In an advantageous embodiment of the method according to the invention, the time of processing is additionally determined, in particular corrected, depending on the correction data.

[0020] In an advantageous embodiment of the method according to the invention, method step B includes method step B.1, wherein the position of the workpiece is detected before the workpiece is processed using the processing radiation, and after method step B.1, movement data of the workpiece is recorded in method step B.2. As a result, the position of the workpiece is initially recorded in method step B.1. By recording the movement data in method step B.2, a precise calculation of the workpiece trajectory is possible.

[0021] In particular, it is advantageous that the acquisition of the movement data according to method step B.2 starts at the latest when method steps B.1 are carried out and is continued at least until the structure is created by means of the processing radiation, preferably until the creation of the structure by means of the processing radiation is completed.

[0022] This ensures seamless recording of movement data from the time of position detection to the time of processing, in particular the completion of processing, so that all changes in the position of the workpiece due to external influences are recorded from the time of position detection.

[0023] Advantageously, in method steps B.2, the movement data of the workpiece are recorded by means of a plurality of optical detectors, in particular by means of a plurality of separate optical detectors, preferably by means of detectors arranged in an array.

[0024] The use of a plurality of optical detectors for motion detection has the advantage that detection over a longer distance is possible, and by comparing the motion data, a rotation of the workpiece, in particular about an axis perpendicular to the transport direction, is also detected. For precise detection of the movement of the workpiece, it is advantageous to arrange the optical detectors in an array, particularly preferably in a grid arrangement, with the detectors being arranged at the grid intersection points in a grid with rectangular, preferably square, cells.

[0025] The array preferably has at least 2, in particular at least 3, preferably at least 30 detectors, in particular 32 detectors. The array preferably has rows aligned transversely to the transport direction, with at least 2, preferably 4, preferably at least 3 sensors being arranged in each row. The array preferably has at least 2, preferably at least 4, in particular at least 8 rows.

[0026] In an advantageous further development, the array has, in addition to the detectors for motion detection, at least one detector for position detection, preferably several detectors for position detection.

[0027] Advantageously, in process steps B.1 and B.2, the characteristic data are acquired using different optical detectors, in particular detectors arranged in separate housings. This allows the detectors to be arranged spatially spaced from one another.

[0028] In an advantageous embodiment, the array of detectors comprises a plurality of data processing units. In particular, it is advantageous for each detector of the array to have its own data processing unit for processing the raw signals measured by the detector, particularly preferably for outputting digital measurement signals, preferably speed signals, which represent the measured speed of the workpiece in at least one, preferably two dimensions. Therefore, each detector preferably has a processor unit, in particular a signal processing processor (DSP), preferably with at least one microprocessor, and preferably a program and data memory.

[0029] This has the advantage that decentralized signal processing enables particularly fast calculation of the workpiece's movement data.

[0030] Advantageously, the device for the detectors has at least one data line to the control unit, so that a plurality of the detectors of the array, preferably all detectors of the array, are connected in parallel to the control unit. This allows data from the detectors to be read out in parallel, resulting in a higher processing speed when calculating the workpiece's movement data. In particular, differently designed detectors can be used, and conventional, commercially available detectors can be used.

[0031] The control unit preferably has at least one processor unit, preferably with one or more microprocessors, in particular with an FPGA (Field Programmable Gate Array). Furthermore, the control unit preferably has at least one program and data memory connected to the processor unit.

[0032] Advantageously, the movement data of the workpiece is measured using the motion sensors on a side of the workpiece opposite the side on which the workpiece is being processed using the processing radiation. This allows movement measurement even during the processing of the workpiece, and the arrangement of the motion sensors is not spatially restricted by the beam path of the processing radiation or optical components for the processing radiation.

[0033] Preferably, the workpiece for processing rests on the transport device, and processing by means of the processing radiation takes place from above. Therefore, the movement data of the workpiece is advantageously recorded from below. In particular, it is advantageous that at least some of the movement sensors, preferably the array of movement sensors, and particularly preferably all of the movement sensors, are arranged on the side of the transport device opposite the deflection unit, in particular below the transport device.

[0034] To improve measurement quality, additional illumination is advantageous, in particular infrared illumination, directed particularly from above onto the workpiece. Advantageously, when the correction data is recorded, the workpiece is illuminated using infrared radiation, in particular from the side of the workpiece opposite the sensor. The device therefore preferably has a radiation source for infrared radiation, which is preferably arranged and designed to illuminate the workpiece from the side on which processing takes place. It is advantageous that in method step B.1, location data of the workpiece is recorded using at least one light barrier, and in method step B.2, movement data of the workpiece is recorded using optical tracking sensors. Light barriers and tracking sensors are standard components that can be purchased commercially at low cost and, at the same time, with high measurement precision.

[0035] Greater precision in position detection is achieved by determining the location data of the workpiece using a camera or an optical micrometer.

[0036] It is therefore advantageous that in method step B.1 location data of the workpiece (2) are recorded by means of at least one position sensor from the group consisting of a light barrier, a camera and an optical micrometer.

[0037] In an advantageous embodiment of the method according to the invention, at least one image, in particular a spatially resolved image and / or a processed spatially resolved image, in particular a spatially resolved image processed by Fourier transformation, of the surface of the workpiece on which the processing is carried out using the processing radiation is acquired in method step B. Using image analysis methods known per se, a structure created by the processing radiation can be localized in the spatially resolved image, so that position data of the structure can be determined from the spatially resolved image. Therefore, the position of a structure created on the workpiece by the processing radiation is preferably determined using the acquired spatially resolved image.

[0038] In particular, it is advantageous to take a plurality of images during processing so that a change in the position of the structure produced by the processing radiation can also be determined.

[0039] Advantageously, structural dimensions of the structure created by means of the processing radiation, in particular at least a distance between spaced-apart structural sub-regions of the structure created by means of the processing radiation, are compared. Alternatively, or preferably additionally, it is advantageous that at least a distance between several of the structures created by means of the processing radiation is compared with the structures captured with the spatially resolved image and / or a distance of the structure formed by means of the processing radiation to one or more edges of the workpiece is compared. In this way, a deviation of the distances from the predetermined distances can be detected and, for further processing, a correction of the time of processing and / or the deflection of the processing radiation can be carried out by means of the optical deflection unit in order to reduce, preferably avoid, the detected deviation.

[0040] Advantageously, the workpiece is illuminated during the acquisition of the correction data, particularly preferably using infrared light. The device according to the invention therefore preferably comprises an illumination device, particularly preferably an illumination device designed to emit infrared radiation.

[0041] It is within the scope of the invention to use different types of processing radiation for processing, in particular ion beams. The use of electromagnetic radiation, in particular laser radiation, is particularly preferred. It is therefore particularly advantageous that the workpiece is processed using laser radiation in method step B. Laser radiation has a high energy density and low divergence and is therefore particularly suitable for creating structures on a workpiece.

[0042] Another source of error when machining a workpiece using machining radiation occurs when workpieces are uneven or have different height profiles. The method and device according to the invention are particularly suitable for machining flat, particularly plate-like workpieces, in particular for machining semiconductor substrates for the production of components, in particular for the production of photovoltaic solar cells.

[0043] Advantageously, therefore, in the method according to the invention, a workpiece is provided on the transport device which is a dimensionally stable workpiece, in particular a flat, in particular plate-like workpiece, preferably a semiconductor substrate, particularly preferably a photovoltaic solar cell.

[0044] Advantageously, therefore, the device according to the invention is designed to form a structure on a workpiece, which workpiece is a dimensionally stable workpiece, in particular a flat, in particular plate-like workpiece, preferably a semiconductor substrate, particularly preferably a photovoltaic solar cell.

[0045] Such flat workpieces may have unevenness, so that a height difference exists between different locations of a workpiece lying on the transport device, in particular between the edges and a central area of ​​the workpiece.

[0046] In an advantageous development of the method according to the invention, a height profile of the workpiece, preferably of the processing side of the workpiece, is recorded. The processing side of the workpiece is the side that is exposed to processing radiation. In addition, at least one of the parameters

[0047] Time of processing; the deflection of the processing radiation by means of the deflection unit; focusing of the processing radiation by means of a focusing device adapted, in particular corrected, depending on the height profile. In particular, it is advantageous to adapt, in particular correct, the time of processing and / or the deflection of the processing radiation by means of the deflection unit.

[0048] Depending on the angle at which the processing beam impinges on the surface of the workpiece, a height difference, particularly due to an uneven workpiece, can lead to a location deviation during processing. Therefore, an adjustment, in particular a correction of the time of processing and / or the deflection of the processing beam, is advantageously carried out using the deflection unit in order to correct a location deviation due to a height difference detected by the height profile.

[0049] Advantageously, a focusing device is used during processing to focus the processing radiation onto a processing point on the workpiece. This allows higher energy densities to be achieved and smaller structures to be formed. With knowledge of the workpiece's height profile, the focusing device is preferably controlled such that the processing radiation is always focused onto the workpiece's surface.

[0050] This prevents incorrect focusing of the processing radiation due to height differences of the workpiece, in particular bending of a flat workpiece.

[0051] The object stated at the outset is further achieved by a device for forming a structure on a workpiece by means of processing radiation according to claim 11.

[0052] The device according to the invention comprises a transport device for moving the workpiece along a movement path, a radiation source for generating the processing radiation, and a control device for controlling the timing of the processing and / or the deflection of the processing radiation for processing the workpiece. Furthermore, the device comprises optical sensors for detecting position data of the workpiece.

[0053] It is essential that the optical sensors are designed as motion sensors for detecting movement of the workpiece, and that the device additionally comprises at least one optical position sensor for detecting location data of the workpiece. It is within the scope of the invention to use a sensor that is technically designed as a motion sensor as a position sensor. Thus, the degree of coverage of a sensor field of a motion sensor can be measured in order to measure the position of the workpiece relative to the motion sensor, and the motion sensor can be positioned so that the detector, which is designed as a motion sensor, represents a position sensor.The device according to the invention thus enables the position of the workpiece to be detected by means of the position sensor and the movements to be detected by means of the motion sensors, so that, starting from the detected position, a workpiece trajectory can be determined using the data from the motion sensors, which corresponds to the actual trajectory, ie deviations due to changes in speed during transport by the transport device or a movement of the workpiece on the transport device are also taken into account.

[0054] The method according to the invention has the advantage of achieving precise alignment of the processing radiation to the desired processing location on the surface of the workpiece. This enables the use of optical elements such as cylindrical lenses, as described below.

[0055] Advantageously, the detection range of the position sensor is therefore arranged in a transport direction of the transport device upstream of the detection range of at least a subset of the motion sensors, preferably upstream of the detection range of all motion sensors. This enables the calculation of the workpiece trajectory using the data from the motion sensors during transport of the workpiece, starting from the moment the position is detected by the position sensor.

[0056] Advantageously, at least a subset of the motion sensors, preferably all motion sensors, are designed as tracking sensors. Alternatively, or preferably additionally, the position sensor is designed as a light barrier. As previously described, commercially available tracking sensors and light barriers can be used, which enable cost-effective, high-precision measurements. As previously described, greater precision is achieved in an advantageous embodiment in which the position sensor is designed as a camera or optical micrometer.

[0057] Optical tracking sensors are known, in particular, for use in computer mice for motion detection. Such tracking sensors are advantageously used as optical tracking sensors. It is therefore advantageous to design the optical tracking sensors as described in US Pat. No. 7,057,148 B2.

[0058] The optical deflection unit preferably comprises one or more movable mirrors, in particular galvanometric mirrors. In a further advantageous embodiment, the deflection unit comprises at least one polygonal mirror wheel. In particular, it is advantageous to design the deflection unit with a combination of at least one galvanometric mirror and a polygonal mirror wheel.

[0059] As previously described, it is advantageous to consider a height profile of the workpiece. The device according to the invention therefore advantageously comprises a height profile measuring unit for determining a height profile of a workpiece arranged on the transport device.

[0060] The height profile measuring unit is preferably designed as a triangulation sensor, wherein the height profile is preferably determined by means of triangulation measurement with laser line or stripe light projection.

[0061] If the height data is known, the processing time at the top and / or the deflection of the moving radiation can be corrected using the optical deflection unit to correct the processing location on the workpiece.

[0062] Advantageously, the device according to the invention comprises a focusing device for the processing radiation. As described above, this allows the energy density to be increased and structures with smaller dimensions to be produced. Advantageously, the control unit is designed to cooperate with the height profile measuring unit and the focusing device in order to control the focusing unit depending on the height profile data of the height profile measuring unit.

[0063] This ensures that the focus of the moving radiation is corrected even in the event of height differences in the workpiece, in particular if the workpiece is uneven, and in particular always lies on the surface of the workpiece or follows the surface. Advantageously, the focusing unit has a passive component, in particular an optical lens with a fixed focal length, and an active component, in particular a liquid lens or a mirror system, wherein the active component shifts the focus depending on the height data of the height profile measuring unit, e.g. a liquid lens or a mirror system. Advantageously, the focusing unit is designed and controlled as described in Jahn, Axel, 3-dimensional beam shaping for dynamic adjustment of focus position and intensity distribution for laser welding and cutting, http: / / publica.fraunhofer.de / documents / N-645639.html.

[0064] The device according to the invention is preferably designed to carry out the method according to the invention, in particular an advantageous embodiment thereof.

[0065] Advantageously, the optical sensors are therefore designed such that during the machining of the workpiece by means of the machining radiation, correction data of the workpiece are detected by means of at least one optical sensor of the device, wherein the correction data comprise movement data of the workpiece and / or position data of a structure produced on the workpiece by means of the machining radiation and the control device is designed to cooperate with the optical sensors so that, depending on the correction data, the deflection of the machining radiation is adapted, in particular corrected, by means of the deflection unit by means of the control device.

[0066] This achieves the advantages previously explained in relation to claim 1.

[0067] It is within the scope of the invention that the transport device is designed to transport the workpiece along a non-rectilinear path of movement. In particular, the transport of the workpiece on a curved, in particular circular, path of movement is within the scope of the invention. The formation of a structure on a workpiece using the roll-to-roll process (R2R process), in particular on a strip-shaped workpiece, is also within the scope of the invention. For integration into an inline process, it is advantageous if the transport device is designed to transport the workpiece on a rectilinear path of movement. As described above, the method and the device according to the invention enable the workpiece to be exposed to the processing radiation with great precision at the desired location on the surface of the workpiece.This can be combined particularly advantageously with optics that produce smaller structures through a large numerical aperture but only have small image fields, in particular microlens arrays or cylindrical lenses. By transporting the workpiece, it is possible to create the small structures with high spatial accuracy even over large areas. It is generally known that cylindrical lenses can be advantageously used to form structures on a workpiece using processing radiation, as described, for example, in Khan et al., "Formation of thin laser ablated contacts using cylindrical lens," https: / / doi.org / 10.1063 / 5.0056740.

[0068] Advantageously, an optical element for focusing the processing radiation, in particular an optical lens, preferably a cylindrical lens, is arranged in the beam path of the processing radiation between the deflection unit and the workpiece. The optical element, preferably the cylindrical lens, is preferably arranged close to the workpiece, in particular at a distance of less than 20 cm, more preferably less than 10 cm, in particular less than 5 cm from the workpiece. This allows particularly narrow structures to be formed.

[0069] Further advantageous features and preferred embodiments are explained below with reference to exemplary embodiments and the figures. Herein:

[0070] Figure 1 shows a first embodiment of a device according to the invention for forming a structure on a workpiece by means of processing radiation;

[0071] Figure 2 is a plan view of a sensor unit of the device shown in Figure 1;

[0072] Figure 3 is a plan view of a machined workpiece and Figure 4 is a second embodiment of a device according to the invention.

[0073] All figures are schematic representations, not to scale. Identical reference symbols in the figures indicate identical or equivalent elements.

[0074] The embodiments of an inventive device for forming a structure on a workpiece using processing radiation, shown in side views in Figures 1 and 4, are designed for processing semiconductor substrates using laser radiation. The semiconductor substrates represent precursors for producing photovoltaic solar cells. The precursors comprise a substrate in the form of a silicon wafer, on which a dielectric layer, in this case a silicon dioxide layer, is formed on a processing side located at the top in the figures. Using the processing radiation in the form of laser radiation, several parallel, rectilinear structures are formed by laser ablation. The structures thus represent linear openings in the dielectric layer.

[0075] The first embodiment of an inventive device for forming a structure on a workpiece using processing radiation, shown in Figure 1, comprises a transport device 1 for moving workpieces 2, which, as described above, are designed as precursors for producing a photovoltaic solar cell. The transport device 1 comprises a conveyor belt onto which the workpieces 2 are placed and moved from left to right along a rectilinear path of movement in the direction of the arrows shown in Figures 1 and 4.

[0076] Figures 1 and 4 each show a side view of the devices, so that only one edge of the flat workpieces 2 is shown.

[0077] The device according to Figure 1 further comprises a radiation source 3 designed as a laser for generating the processing radiation in the form of laser radiation. In this case, the laser is designed as a solid-state laser with a wavelength of 1064 nm and a pulse duration of 4 ns. The device further comprises a deflection unit 4, which in this case has a motor-rotatable mirror for deflecting a laser beam 3a from the radiation source 3 perpendicular to the transport direction and perpendicular to the upper processing side of the workpieces 2, and thus perpendicular to the plane of the drawing in Figure 1.

[0078] The device also has optical sensors:

[0079] A position sensor 5 is arranged in the transport direction in front of the area of ​​the device in which the workpieces 2 are processed by means of the laser beam 3a.

[0080] The position sensor 5 has a plurality of light barriers which are arranged in a straight line perpendicular to the transport direction and thus perpendicular to the plane of the drawing in Figure 1.

[0081] For this purpose, mirrors are mounted in an area of ​​the transport device 1 below the workpieces 2 transported by the transport device. The transport means of the transport device 1, in this case the conveyor belt, is designed such that no elements of the conveyor belt are arranged in the area of ​​the mirrors, so that the optical path between the housing 5 of the position sensor 5 arranged at the top in Figure 1 and the mirrors arranged in the transport direction 1 is only obscured by the workpieces 2.

[0082] The position sensor 5 thus detects the point in time at which a leading edge of the workpiece 2, in the transport direction, obscures the optical beam path of the light barrier. Furthermore, a time offset of the obscuration of the individual light barriers arranged in a straight line perpendicular to the transport direction can also be used to detect an inclined position of the workpiece, provided the leading edge of the workpiece is not perpendicular to the transport direction. The position sensor thus detects the absolute position of the workpiece 2 relative to the device.

[0083] The optical sensors further comprise a motion sensor array 6. The motion sensor array 6 has a plurality of optical tracking sensors 6a, which are arranged at the intersection points of a square grid. Figure 2 shows a top view of the motion sensor array 6, with the optical tracking sensors each depicted as a circle. By way of example, the optical tracking sensor 6a is provided with a reference symbol in the upper left corner.

[0084] The optical tracking sensors are designed as described in US Pat. No. 7,057,148 B2. A single tracking sensor consists of an optical detector, in this case with 30x30 pixels, an integrated illumination unit, and a microcontroller containing a digital signal processing unit for calculating the motion data.

[0085] By means of the optical tracking sensors of the motion sensor array 6, the movement of the workpiece 2 is detected from the time at which the position of the workpiece is detected by the position sensor 5 until at least the time at which the workpiece is processed with the laser beam 3a. Due to the large number of optical tracking sensors 6a, a temporal movement of the workpiece and also a rotation of the workpiece can be detected by differences in the movement speed and, in particular, components in the movement speed that are perpendicular to the transport direction.

[0086] The detection range of the optical tracking sensors 6a is thus arranged in the transport direction after the detection range of the position sensor.

[0087] Figure 3 shows a workpiece 2 in plan view from above, which has already been completely machined. The black parallel lines mark the recesses which were created by laser ablation using the laser beam 3a. During machining, the rectilinear recesses are created parallel to the transport direction. In the device shown in Figure 1, however, the laser beam can only be moved perpendicular to the transport direction using the deflection unit 4, as described above. However, the movement of the laser beam and the ablation of the dielectric layer to form the recesses occur at a considerably higher speed compared to the movement speed of the workpiece 2 on the transport device 1. Therefore, adjacent sections of the structures can always be created in sequential succession.Due to an extension of the ablations generated by the laser also parallel to the direction of movement, overlapping recesses are successively created in each structure in the transport direction, so that a continuous rectilinear recess is formed for each structure.

[0088] The device according to the embodiments illustrated in Figures 1 and 4 each has a control device 7. This is connected to the optical sensors for detecting the measurement data from the optical sensors, as well as to the radiation source 3 for switching the beam generation on and off, and to the deflection unit for controlling the deflection of the laser beam 3a by means of the deflection unit.

[0089] The connection to the motion sensor array 6 is not shown graphically for reasons of clarity.

[0090] The device according to Figure 1 is designed to carry out an embodiment of a method according to the invention:

[0091] In method step A, a workpiece 2 is provided on the transport device 1. In method step B, the workpiece 2 is moved along the rectilinear movement path indicated by an arrow by means of the transport device 1 and the workpiece 2 is processed by means of the processing radiation in the form of a laser beam 3a, while the workpiece 2 is moved by the transport device 1. The time of processing is controlled by means of the control device 7, and the location of processing of the workpiece by means of the processing radiation is controlled by means of the optical deflection unit 4 controlled by the control device 7, in order to form the rectilinear, parallel structures shown in Figure 3.

[0092] It is essential that in method step B, during the machining of the workpiece, correction data of the workpiece are acquired by means of the machining radiation with sensors 5 and 6. In this case, the correction data comprise the position data acquired by position sensor 5 and the movement data of workpiece 2 acquired by the optical tracking sensors 6a of motion sensor 6.

[0093] Depending on the correction data by means of the control device, the time of processing and / or the deflection of the processing radiation is corrected by means of the deflection unit 7.

[0094] If, for example, the plurality of light barriers of the position sensor 5 detects that the front edge of the workpiece 2 is not perpendicular but oblique to the transport direction, the time for generating the structures is changed accordingly, since when the workpiece 2 enters the processing area obliquely, initially only one structure and then an increasing number of structures are formed in order to ensure a uniform distance between the start of the structures and the edge of the workpiece.

[0095] In addition, the deflection of the laser beam 3a is corrected by means of the deflection unit 7, since the structures must be formed in the reference system of the processing device according to the angle detected by the position sensor 5, which the front edge of the workpiece 2 includes with the transport direction, in order to form structures on the workpiece 2 which run parallel to the side edges or perpendicular to the front edge of the workpiece 2.

[0096] Figure 4 shows a second embodiment of a device according to the invention. Essential elements and functionalities are identical to the first embodiment. To avoid repetition, only the essential differences will be discussed below:

[0097] The position sensor 5' of the device shown in Figure 4 is designed as a spatially resolving camera, in this case with a CMOS chip.

[0098] The deflection unit 4' of the device according to Figure 4 has two galvanometric mirrors which enable deflection in any spatial direction along the processing plane, so that the laser beam 3a can be deflected not only with components perpendicular to the transport direction, but also with components parallel to the transport direction of the transport device 1.

[0099] In a modification of the exemplary embodiment, a combination of a polygon mirror wheel and a galvanometer is used as the deflection unit 4' to enable the beam to move particularly quickly parallel to the workpiece and perpendicular to the direction of movement. The galvanometer then corrects the movement along the transport direction, while the beam is moved uniformly perpendicular to the transport direction. An advantage of this design is the possibility of realizing a particularly large processing field with a large numerical aperture and very high processing speed.

[0100] In addition, a focusing device 8 is arranged on the deflection unit 4 in order to focus the laser beam 3a onto the upper processing side of the workpiece 2 in Figure 4.

[0101] Furthermore, the device according to Figure 4 has a height profile measuring unit 9 for measuring a height profile of the machining side of the workpiece 2.

[0102] Position sensor 5', focusing device 8 and height profile measuring unit 9 are also connected to the control unit 7.

[0103] In the device shown in Figure 4, an image of the processing area can be recorded in a continuous sequence using the position sensor 5', which is designed as a camera. A leading edge of the workpiece 2 is detected by image analysis. Using this data, the position of the workpiece 2 as it enters the processing area of ​​the device can be detected, and in particular, any inclination of the incoming leading edge of the workpiece 2, provided it is not perpendicular to the transport direction of the transport device 1. This enables a correction as already described for embodiment 1.

[0104] Furthermore, the device shown in Figure 4 enables the position of the structures created by the processing radiation to be detected by means of the position sensor 5'. In the present exemplary embodiment, the distance between the structures and the distance to the edges of the workpiece 2 are predetermined. Image analysis can be used to determine the distance between the structures and the distance to the edges during the creation of the structures. If this distance does not match the predetermined distance values, the deflection of the laser beam is corrected by means of the deflection unit 4' in order to achieve the correct distances at least during subsequent processing.

[0105] The device according to Figure 4 additionally has a height profile measuring unit 9. This is designed to capture a two-dimensional height profile of the workpiece 2. For this purpose, the height profile measuring unit is designed as a laser triangulation measuring head.

[0106] The height profile of a workpiece 2 determined by means of the height profile measuring unit 9 is transmitted to the control device 7 and this controls the focusing device 8 accordingly, so that the focus is always at the height specified by the height profile at the current processing location and thus always on the surface of the processing side of the workpiece 2.

[0107] The device according to Figure 4 additionally features the motion sensor array 6 already described in relation to Figure 1 for recording motion data. This provides redundant information on the location and movement of the workpiece 2. Using correction functions, for example, arithmetic averaging, the accuracy of recording the workpiece's characteristic data can be increased.

[0108] In a modification of an embodiment of a method according to the invention, only characteristic data are recorded by means of the position sensor 5', which records position data of the structure produced on the workpiece by means of the processing radiation, in this case the position data of the rectilinear recesses on the workpiece 2 produced by means of the laser beam 3a.

[0109] In the embodiment shown in Figure 4, the laser beam 3a is deflected by the deflection unit 4 onto a cylindrical lens 10. The cylindrical lens 10 is aligned with the cylinder axis transverse to the transport direction. The use of a cylindrical lens enables the formation of particularly narrow structures, in particular narrow lines parallel to the cylinder axis of the cylindrical lens. The cylindrical lens 10 has a particularly short focal length, in this case approximately 150 mm, and can thus be combined with the transport system in a particularly advantageous manner, since only slight movement of the beam in the transport direction needs to be ensured due to the movement of the workpiece. Since the surface to be processed is not restricted along the transport direction, very small structures can be realized on a large area. The distance between the cylindrical lens 10 and the workpiece 2 is in the range 1 cm to 5 cm.

[0110] Reference symbol list

[0111] 1 Transport device 2 Workpiece

[0112] 3 Radiation source

[0113] 3a Laser beam

[0114] 4, 4' deflection unit

[0115] 5.5' Position sensor 6 Motion sensor array

[0116] 6a optical tracking sensors

[0117] 7 Control device

[0118] 8 Focusing device

[0119] 9 Height profile measuring unit 10 Cylindrical lens

Claims

Claims: Method for forming a structure on a workpiece (2) by means of machining radiation, comprising the method steps a. providing the workpiece (2) on a transport device (1); b. moving the workpiece (2) along a path of motion by means of the transport device (1) and Processing the workpiece (2) by means of the processing radiation while the workpiece (2) is moved by means of the transport device (1), wherein the time of processing and preferably the location of processing of the workpiece (2) by means of the processing radiation is controlled by means of a control device (7) in order to form the structure, characterized in that in process step B during the processing of the workpiece (2) by means of the processing radiation correction data of the workpiece (2) are acquired by means of at least one optical sensor,wherein the correction data comprise motion data of the workpiece (2) and / or position data of a structure generated on the workpiece (2) by means of the processing radiation, and that, depending on the correction data, the deflection of the processing radiation is determined, in particular corrected, by means of the control device (7) by means of the deflection unit (4, 4'). Method according to claim 1, characterized in that, in process step B, in a process step B.1 before the processing of the workpiece (2) by means of the processing radiation, a position detection of the workpiece (2) takes place, and after process step B.1, in a process step B.2, motion data of the workpiece (2) are acquired. Method according to claim 2, characterized in that that the acquisition of the motion data according to process step B.2 starts at the latest when process step B.1 is carried out and continues at least until the structure is generated by means of the processing radiation, preferably until the generation of the structure by means of the processing radiation is completed.

4. Method according to one of claims 2 to 3, characterized in that in method step B.2 the motion data of the workpiece (2) are recorded by means of a plurality of optical detectors, in particular by means of a plurality of separate optical detectors, preferably arranged in an array of detectors.

5. Method according to one of claims 2 to 4, characterized in that in method steps B.1 and B.2 the characteristic data are recorded by means of different optical detectors, in particular by means of detectors arranged in separate housings.

6. Method according to claim 5, characterized in that in method step B.1 location data of the workpiece (2) are recorded by means of at least one position sensor from the group, light barrier, camera, optical micrometer and in method step B.2 movement data of the workpiece (2) are recorded by means of optical tracking sensors (6a).

7. Method according to one of the preceding claims, characterized in that in method step B at least a spatially resolved image, in particular a processed spatially resolved image, in particular a spatially resolved image processed by means of Fourier transformation, of the surface of the workpiece (2) on which the processing by means of the processing radiation is carried out is acquired, and preferably a position determination of a structure generated on the workpiece (2) by means of the processing radiation is carried out by means of the image. A method according to claim 7, characterized in that structural dimensions of the structure generated by the processing radiation, in particular at least a distance between spaced-apart structural sub-regions of the structure generated by the processing radiation, are compared, and / or at least a distance between several of the structures generated by the processing radiation is compared with the structures captured with the spatially resolved image, and / or a distance of the structure formed by the processing radiation to one or more edges of the workpiece is compared. A method according to any of the preceding claims, characterized in that in process step B the workpiece (2) is processed by means of laser radiation. A method according to any of the preceding claims, characterized in that a height profile of the workpiece (2), preferably of the processing side of the workpiece (2), is captured, and at least one of the corrections The processing time; the deflection of the processing radiation by means of the deflection unit (4, 4'); focusing of the processing radiation by means of a focusing device is carried out depending on the height profile.

1. Device for forming a structure on a workpiece (2) by means of processing radiation, with a transport device (1) for moving the workpiece (2) along a preferably straight path of motion, a radiation source for generating the processing radiation and a control device (7) for controlling a processing time and / or the deflection of the processing radiation for processing the workpiece (2) and with optical sensors for acquiring position data of the workpiece (2), characterized in that the optical sensors are used as motion sensors for acquiring a The device is configured to detect movement of the workpiece (2) and additionally comprises at least one optical position sensor (5, 5') for detecting position data of the workpiece (2). The device according to claim 1, characterized in that the detection range of the position sensor is arranged in a transport direction of the transport device (1) in front of the detection range of at least a subset of the motion sensors. The device according to any one of claims 1 to 12, characterized in that at least a subset of the motion sensors are configured as tracking sensors and / or that the position sensor is configured as a light barrier, camera, or optical micrometer.Device according to one of claims 1 to 13, characterized in that the device has a height profile measuring unit (9) for determining a height profile of a workpiece (2) arranged on the transport device (1), in particular that the device has a focusing device (8) for the processing radiation and the control unit is designed to interact with the height profile measuring unit (9) and the focusing device (8) in order to control the focusing device (8) depending on the height profile data of the height profile measuring unit (9).Device according to one of the preceding claims 1 to 14, characterized in that the optical sensors are designed such that, during the processing of the workpiece (2) by means of the processing radiation, correction data of the workpiece (2) are acquired by means of at least one optical sensor, wherein the correction data comprise movement data of the workpiece (2) and / or position data of a structure generated on the workpiece (2) by means of the processing radiation. that the control device (7) is designed to work together with the optical sensors, so that, depending on the correction data, the timing of the processing and / or the deflection of the processing radiation is corrected by means of the deflection unit (4, 4') using the control device (7).

Images