Method and system for manufacturing functionally high-quality electrically conductive layers

Abstract

The present invention relates to a method and a system for manufacturing an electrically conductive layer having functionality, in particular electrical conductivity, which is as homogeneous as possible, specified, or locally different in a defined way. In the method, layer material is applied to a surface and is converted, by the action of preferably at least one energetic beam, into a preliminary electrically conductive layer having higher electrical conductivity. The preliminary electrically conductive layer is then scanned with at least one THz beam of continuous THz radiation, with spatial resolution. From a measurement of the reflectivity of the preliminary electrically conductive layer with respect to the THz beam, spatially resolved electrical conductivity of said layer is determined. If points in the preliminary electrically conductive layer which have too low or too high an electrical conductivity are detected, said points are then locally post-treated with the energetic beam in order to modify the electrical conductivity in order to obtain the electrically conductive layer having functionality which is as homogeneous as possible, specified, or locally different in a defined way. The method allows high-quality electrically conductive layers to be produced on an industrial scale.

Description

[0001] Process and system for the production of functionally high-quality electrically conductive layers

[0002] Technical application area

[0003] The present invention relates to a method for producing electrically conductive layers of preferably homogeneous or locally defined different functionality, in particular electrical conductivity, in which layer material is applied to a surface and transformed into an electrical layer with higher electrical conductivity by the action of at least one energetic beam. The invention also relates to an apparatus for carrying out the method on an industrial scale.

[0004] Electronic sensors are used in almost all areas of society. Accelerometers in mobile radios, strain gauges on automotive drive shafts, and sensors on medical implants are just a few examples. Among other factors, the quality of sensors depends particularly on the quality and reproducibility of the electrically conductive layers they contain. Nowadays, prefabricated electronic sensors are primarily applied to higher-value components after manufacturing. Therefore, variations in sensor production are still tolerable. In contrast, for sensors that are additively applied directly to the component during the production process, for example, using digital printing and laser technologies, sensor quality is a crucial criterion for the functionality of the entire component due to the high level of refinement involved.

[0005] In printed electronics, a dispersion, solution, sol-gel, paste, or similar material is applied to a substrate. The necessary printing aids are then evaporated, pyrolyzed, etc., from the printed layer, and, if required, the remaining particulate functional materials are sintered, cured, crosslinked, crystallized, or otherwise processed using a thermal method. Post-treatment can be carried out using ovens, infrared radiation, hot plates, flash lamps, laser beam processes, and more. Most methods result in a global treatment of the printed layer, meaning that the entire printed area exposed to the process receives the same energy. With laser processes, the energy input can be applied selectively, i.e., locally, allowing for site-specific adjustments to the post-treatment intensity of the printed material.

[0006] The manufacturing quality of conventional printed electronics (PEEs) is currently too low for industrial applications, with conductivity fluctuations of up to 30% (deviation from the target value). Deviations of less than 2% must be achieved. A similar situation exists with layers manufactured using other methods (e.g., CVD, PVD, etc.), which exhibit variations in density, crystal structure, dopant concentration, and other properties. These variations can also lead to functional impairments of the layer and, consequently, of the product.

[0007] State of the art

[0008] High-precision electrically conductive layers or layer structures are currently applied using CVD / PVD or electroplating, which requires either a high vacuum or an electroplating bath. This limits component size, necessitates very high acquisition costs, and requires subsequent structuring with lasers or chemicals. Promising alternatives from the field of printed electronics utilize the wet-chemical deposition of electrically conductive materials such as nanoparticulate metal and MOD (metal organic deposition) inks, conductive polymers, transparent oxides (TCO), carbon nanotubes, and graphene, for example, with structuring printing processes (inkjet, screen printing, etc.). Layers applied in this way require thermal post-treatment to achieve the desired layer function. Fluctuations in material deposition (conductor thickness / width) necessitate particle sintering, crosslinking, reduction, curing, etc.Homogeneous thermal or photonic post-treatment (e.g., oven, UV, IR, flash lamp) can lead to conductivity variations along the sensor structures. In the case of a strain gauge, this would be, for example, the resistance layer of the measuring grids. If these are monitored at all, deviating structures are marked as rejects and remanufactured. Silicon is the material of choice for MEMS sensors. It can be applied in layer thicknesses of up to several tens of micrometers, is sufficiently electrically conductive and mechanically stable in its crystalline form, has a coefficient of thermal expansion identical to that of the underlying silicon substrate, can be machined with high precision using microelectronics and microsystems engineering methods, and is used for the fabrication of MEMS structures for inertial and infrared sensors, oscillators, etc.Since the miniaturization of such systems, which primarily consist of separate MEMS sensor and electronic chips connected by bond wires or of units processed side-by-side, will reach its limits in the near future, research is being conducted into alternatives that enable the vertical, monolithic stacking of MEMS and electronics. One variant is the selective laser crystallization of amorphously deposited silicon layers onto the active electronic circuits. This allows sensors and electronics to be built on top of each other (vertically monolithically integrated). However, achieving uniform electrical conductivity through laser crystallization is still subject to variations that depend on the processing location and the associated thermal conductivity on the wafer (edge ​​vs. center processing, underlying oxide layer thickness and circuit density, etc.).

[0009] High-resolution conductivity measurement can be achieved using various approaches. THz near-field systems offer the highest spatial resolution of up to 3 pm; however, they only operate at short working distances (a few tens of pm) and have an insufficient traverse speed (5 mm / s) for inline measurement in industrial-scale series production. Furthermore, low surface roughness, or rather, small surface irregularities, are inherently necessary.

[0010] Eddy current measurement systems operate at working distances of a few hundred pm, are axis-based, and are inherently very sensitive to changes in distance. Particularly with embedded conductor tracks, near-field approaches quickly reach their limits due to their shallow penetration depth.

[0011] Current commercial THz free-beam or far-field measurement systems enable working distances of several centimeters, but do not offer integrated algorithms for conductivity analysis, unlike the near-field sensors specifically designed for this purpose. However, access to the raw data and its processing allows the use of these systems for conductivity determination, as described, for example, in Zhuldybina M. et al.: Contactless in situ electrical characterization method of printed electronic devices with terahertz spectroscopy, Sensors (1 Feb 2019), Volume 19, Number 3, 444. Far-field THz systems are based either on purely electronic THz generation with frequency multiplier chains or optoelectronic conversion of infrared laser signals into THz fields.Only the latter systems generate frequencies > 1 THz (frequency of the measurement radiation), which are necessary to achieve the required spatial resolution (> 100 pm) using free-space imaging and integrated algorithms. All currently commercially available optoelectronic THz measurement systems with measurement rates > 10 Hz are based on time-domain spectroscopy with pulsed THz radiation. These methods require a propagation delay between an optical generation and detection pulse, which is achieved either with the aid of optomechanical delay lines or repetition rate modulation of two femtosecond lasers. Both methods are technically very complex and limited to measurement rates of a few hundred Hz. However, to acquire the required feature sizes (100 pm) in a reasonable time at the high scanning speed of the scanner, higher measurement rates are needed, which none of the available techniques have yet achieved.Frequency range or continuous wave THz (cw) measurement methods offer significantly greater flexibility and have so far been used primarily in spectroscopy.

[0012] Imaging THz measurement methods have so far been based on a lateral displacement of the component under investigation or the entire THz optical system, which significantly limits the speed of component acquisition. Therefore, THz measurement systems based on this principle are only suitable for random sampling quality control, but not for inline measurement.

[0013] The CN 1 18 190 864 A off fenbart a non-contact method for detecting the quality of a printed circuit, in which a quality control sample is printed into a reserved area of ​​the printed circuit during manufacturing and scanned with terahertz radiation to determine the conductivity and diffusion properties of the ink in the printing process.

[0014] US Patent 2021208065 A1 describes a test system for printed circuits in which the conductivity of the ink of the printed circuit is determined using a terahertz beam.

[0015] The object of the present invention is to provide a method and a system for producing high-quality electrically conductive layers with as homogeneous, predetermined or defined locally different functionality, in particular electrical conductivity, as possible, which are suitable for the industrial production of electrically conductive layers (e.g. for sensors, antennas, conductors, resistors, etc.) with low reject rates.

[0016] Description of the invention

[0017] The problem is solved by the method and the apparatus according to claims 1 and 9. Advantageous embodiments of the method and the apparatus are the subject of the dependent claims or can be found in the following description and the exemplary embodiment.

[0018] In the proposed method, the electrically conductive layer can be produced on a surface using various manufacturing techniques. For this purpose, layer material is applied to the surface and, through energetic treatment, preferably by the application of at least one energetic beam, transformed into an electrically conductive layer with a higher electrical conductivity than the applied layer material. The applied layer material can be a layer without electrical conductivity or a layer that already exhibits electrical conductivity, e.g., a partially crystalline layer. Depending on the manufacturing technique used, for example, the printed electronics techniques mentioned in the introduction to the description, the resulting layer can be produced in a variety of ways.In printed electronics or the selective laser crystallization of amorphously deposited silicon layers, the conversion to the electrically conductive layer with higher electrical conductivity can involve drying, sintering, recrystallization, melting, or another process. A laser beam is preferably used as the energy beam. However, other energy beams, such as electron or clay beams, can also be used. The application of the energy beam is preferably location-selective with the aid of a suitable scanning device, as is known from the prior art.In the proposed method, the layer material applied to the surface is transformed by energetic action, preferably with the energy beam, into an electrically conductive layer with higher electrical conductivity, hereinafter also referred to as a preliminary electrically conductive layer. In some cases, this preliminary layer does not yet exhibit the desired layer quality, in particular the desired homogeneity of the corresponding functionality or electrical conductivity, the predetermined functionality or electrical conductivity, or the desired locally varying functionality. This preliminary layer is then spatially scanned with at least one THz beam of continuous or pulsed THz radiation. This spatially resolved scanning is achieved by deflecting the THz beam via a suitable dynamic deflection device.A scanning device and imaging optics are directed at and moved across the preliminary electrically conductive layer. The electrical conductivity of this layer is then determined spatially from the reflectivity measurement of this THz beam on the preliminary electrically conductive layer in a known manner. From the resulting spatially resolved conductivity profile, areas of the electrically conductive layer are identified where the electrical conductivity is below or above a predefined target value. These areas are then locally treated with an energetic beam to approximate the target value.The electrical conductivity of these areas is modified to selectively increase or decrease it, thereby obtaining the desired (final) electrically conductive layer with the most homogeneous, predetermined, or defined locally varying functionality, particularly electrical conductivity. This process exploits the fact that, with the selected additive manufacturing techniques, the electrical conductivity of the layer can be further modified by a corresponding post-treatment with the energy beam. If the spatially resolved conductivity profile reveals that the preliminary electrically conductive layer already exhibits sufficiently homogeneous conductivity, no further post-treatment with the energy beam is performed, as the preliminary electrically conductive layer then already corresponds to the desired (final) electrically conductive layer.

[0019] This method can be used to create not only a highly homogeneous electrically conductive layer, but also a layer with a predefined functionality or electrical conductivity, or with defined local variations in functionality or electrical conductivity. For example, a layer with homogeneous functionality might initially be created, but its electrical conductivity might not be within the desired range across the entire layer. This layer can then be post-treated using the proposed method to bring it into compliance. Furthermore, an applied electrical layer could be modified using the proposed method through site-selective laser treatment to create defined local variations in electrical conductivity within the layer, for example, to form conductive traces and resistors (i.e., an electrical circuit).

[0020] The spatially resolved reflectivity measurement using THz radiation employed in the proposed method can be performed inline during the fabrication process of the electrically conductive layers. This is because the use of a scanning device, through which the THz beam is guided across the layer, enables rapid scanning of the preliminary electrically conductive layer. The use of continuous THz radiation allows frequencies of 1 THz or higher for a sufficiently high spatial resolution of the measurement.

[0021] In a particularly advantageous embodiment, reflectivity measurement with THz radiation is performed coherently at only a few THz frequencies, preferably less than 10, thereby further reducing measurement time and data volume. With the proposed method and the associated equipment, high-quality electrically conductive layers with homogeneous, predetermined, or defined locally varying functionality, especially electrical conductivity, can thus be produced on an industrial scale in a single production process. These layers can be used for many sensor applications, which have already been exemplified in the introductory section.

[0022] The proposed system comprises a device for applying the coating material, a location-selective material processing device with which at least one energetic beam can be guided over a coating material applied to a surface in order to convert this coating material into an electrically conductive layer with higher electrical conductivity and / or to post-treat the electrically conductive layer, a THz measuring device with a suitable imaging and scanning device by which a THz beam generated by the measuring device can be guided over the electrically conductive layer, and a control device for controlling the above devices, carrying out the measurement and controlling the post-treatment according to the proposed method.

[0023] The proposed method and the associated equipment can be used for all applications where the production of electrically conductive layers with homogeneous, predetermined, or defined locally varying functionality is required. This applies, for example, to the fields of printed electronics and semiconductor manufacturing (extremely rapid mapping of dopant concentration to the wafer level), e.g., in solar cell production or sensors for mobile consumer devices, automotive, etc. The printed layers can be used, for example, in the wearables sector (especially in smartwatches and fitness trackers, wearables, cameras, skin patches, smart clothes and glasses, and headsets) as well as in the healthcare sector (variable injectors, medical wearables, etc.).The process can also be used advantageously for the production of MEMS components, as well as in the fields of laboratory analysis, process measurement technology, hybrid systems in medical technology, etc. This is, of course, not an exhaustive list.

[0024] Brief description of the drawings

[0025] The proposed method is explained in more detail below using an exemplary embodiment in conjunction with the drawings. These show:

[0026] Fig. 1 shows an example of a process chain for

[0027] Implementation of the proposed method; Fig. 2 shows an example of a THz measurement scheme based on the spatial and frequency domain of a conductor embedded in polymer;

[0028] Fig. 3 shows an example of the dependence of the achievable conductor resistance on the laser area energy used;

[0029] Fig. 4 shows a first example of the configuration of a scanner-based THz optical system in the proposed method;

[0030] Fig. 5 shows a second example of the configuration of a scanner-based THz optical system in the proposed method; and

[0031] Fig. 6 shows a third example of the configuration of a scanner-based THz optical system in the proposed method.

[0032] Ways to implement the invention

[0033] The proposed method and the equipment designed to carry out the method are explained below using the example of a printed conductor. However, this explanation can be applied to all electrically conductive layers to be manufactured or processed.

[0034] In a printed conductor, deviations from the target width and height, which can occur during the printing of the layer material for the conductor, lead to a varying cross-section along the conductor. This, in turn, causes location-dependent conductivity variations in the homogeneous sintering of the printed layer material. For example, in the production of strain gauges (SGs), these variations can lead to sensor detuning, rendering the sensor inaccurate or even unusable. Targeted, location-selective laser processing (e.g., particle sintering) can compensate for these undesirable variations in electrical conductivity by sintering sections with smaller cross-sectional areas more intensely than others. This selective post-sintering results in a uniform conductivity across the length (conductivity layer).

[0035] This is exploited in the proposed method. Figure 1 shows an example of a process sequence according to the invention. The upper part shows a cross-section, and the lower part a top view of the printed layer or conductor track structure. The illustrated process chain comprises the following steps:

[0036] 1) Applying the layer material using a printing process.

[0037] 2) Laser sintering of the printed layer material to produce a solidified layer.

[0038] 3) Spatially resolved measurement of the reflectivity of the ink-printed layer structure sintered or pre-sintered in step 2) using an ultrafast THz measurement method with a scanner-based optical system, whereby the measurement data are linked with the spatial data via the scanner mirror tilt, and a 2D conductivity profile of the layer structure is determined. 4) Site-selective post-sintering with a laser beam, in which areas with a conductivity below the predefinable target value are selectively modified (selectively post-sintered) to achieve a target conductivity.

[0039] 5) Subsequently, to verify the results, a further spatially resolved measurement of the reflectivity of the layer structure can be carried out using the THz measurement method as in step 3) - and if necessary, step 4) can also be repeated.

[0040] This process principle can also be applied to other electrically conductive layers, for example in the fields of semiconductor crystallization, electrode manufacturing (battery & hydrogen), printed circuit boards, or CFRP monitoring. The necessary technology modules for THz measurement and location-selective post-processing are preferably integrated into a single handling system.

[0041] The proposed method and the associated system thus encompass the following sub-areas: a) Fast THz measurement method including system technology (measuring module), b) Scanner-based THz optical system (optics module), c) Algorithms for converting measured values ​​of the

[0042] Reflectivity in conductivities, data handling (measurement / modification map), and d) selective laser processing are combined and integrated into a manufacturing process for electrically conductive layers. To further increase the measurement speed achieved through the use of the scanner-based optics system, and thus make it even more suitable for an inline-capable device, a fundamentally new and application-specific measurement scheme is used in an advantageous embodiment of the proposed method. This scheme allows for even better achievement of the high measurement rates desired for inline measurement. The measurement scheme is based on the fundamental idea that by reducing the measurement bandwidth with knowledge of the sample or layer under consideration, the measurement speed can be increased without any loss of information. The generation and detection of the THz signal are based on photomixing of optical and electrical signals.In this configuration, individual lasers of different wavelengths are selectively mixed to generate only a few specific frequencies within the THz spectrum. To ensure coherent measurements, the lasers are frequency-modulated. Limiting the number of frequencies, preferably less than 10, enables the necessary high measurement rates.

[0043] This principle can be illustrated using an exemplary sample, as shown in Figure 2a: The conductor track to be measured is embedded in a polymer, which lies on a metal substrate. Since partial reflection and transmission of the incident THz wave occurs at each interface, the amplitude and phase of the reflected wave depend on four variables: the thickness of the polymer above (dl) and below the conductor track (d2), the conductivity of the conductor track (L), and the distance of the sample from the THz optics. For an unambiguous determination of the conductivity, all four values ​​must be determined in a single measurement. In a THz reflection spectrum, layer thicknesses appear as Fabry-Perot dips, whose frequency and depth depend on the layer thickness and the conductivity. A measurement at four different THz frequencies at at least one reflection dip (see Fig. 2a) is required.Figure 2b provides four amplitude and four phase values, so that all variables can be uniquely determined. Figure 2b shows a frequency domain representation of the THz reflection spectrum in amplitude and phase.

[0044] For ultra-fast scanning of strain gauges using a THz measurement focus, a nearly diffraction-limited THz optics system, consisting of a scanner and imaging optics, with a high numerical aperture was used in this example. This system enables both agile and precise scanning. Galvanometer scanners are suitable for implementing the scanning system. These allow independent deflection of the beam in both lateral directions. 2D scanners with only one mirror, such as a tip-tilt mirror, can also be used. Focusing is achieved with the aid of a lens system. Scanner-typical distortions are minimized by a suitable optical system and corrected by software during subsequent processing of the spatial data.

[0045] In THz optics, the entrance pupil of the focusing optics lies in the plane of the scanner mirrors for the x and y directions. Since the two mirrors are spatially separated when using a galvanometer scanner, the scanner system also has different pupil positions for the x and y directions, which in turn define the field-dependent principal beam angle. When inspecting surfaces that reflect directionally with this arrangement, a tilt of the principal beam relative to the observed surface causes signal attenuation because the beam paths in the forward and backward directions are no longer coincident, resulting in vignetting. When observing flat, non-tilted surfaces, this vignetting can be completely avoided by an image-side telecentric beam path, in which the scanning mirror is arranged in the object-side principal plane of the scanner lens.Due to the separation of the two mirrors, the telecentralization condition can only be fulfilled for one direction. Alternatively, mapping the first mirror onto the second mirror allows the telecentralization condition to be fulfilled in both directions. Without this mapping, field-independent perpendicular incidence can be achieved for a toric surface by appropriately selecting the mirror positions relative to the scanner object. If, for example, the telecentralization condition is fulfilled for the mirror closer to the object, the principal rays for the other scan direction are convergent, so that field-independent perpendicular incidence is achieved for layers on cylindrical components, e.g., shafts. By appropriately choosing the distance between the two mirrors, the system can be adapted to the shaft diameter in this case.Figures 4 to 6 show examples of different configurations of the THz optics (scanner-based THz optical system) in the proposed method and the associated equipment. In these examples, the THz optics comprise at least one first and one second scanner mirror M1, M2 for the X and Y scan directions, two relay optics RL1, RL2 for imaging the first scanner mirror M1 onto the second scanner mirror M2, and a focusing optic FL. A Z-shifter optic (ZS) is arranged in the beam direction in front of the scanner mirrors M1, M2. The three figures illustrate, by way of example, the configurations for a planar (Fig. 4), a concave-cylindrical (Fig. 5), and a convex-cylindrical target surface IP (Fig. 6), each based on three deflection angles of the first mirror M1.

[0046] Using the two relay optics, e.g., relay lenses, RL1 and RL2, the first scanner mirror M1 is imaged onto the second M2. When the entrance pupil of the focusing optic FL lies on the second mirror M2, the beam path is telecentric on the image side in the X and Y directions, so that a flat target plane IP can be scanned without vignetting, as illustrated in Fig. 4. By varying the distance or optical path length between M1 and RL1 or between M1 and M2, cylindrical components such as shafts can be scanned without vignetting. By varying the distance or optical path length between M2 and FL, spherical components can be scanned without vignetting. A combination of both variations allows any toric component to be scanned without vignetting.By using the z-shifter optics ZS in front of the scanner mirrors M1, M2 or alternatively by scan-synchronous movement of the focusing optics FL in the Z direction, it is achieved that the focus lies on the component surface for the entire scan field, even with curved components.

[0047] To achieve a preferred perpendicular incidence on arbitrarily shaped surfaces, the distance (or optical path length) between the scanner mirrors M1, M2, and / or between the second scanner mirror M2 and the scanner object FL can be varied during surface scanning, thus varying the angle of incidence of the main beam. This adjustment can be made using an optical compensation element, enabling rapid variation of the optical path length. The greatest flexibility is achieved by using two relay optics, where the first relay optic maps the image from the first mirror onto the second mirror with variable image position, and the second relay optic maps the image from the second mirror onto the entrance pupil of the object with variable image position.

[0048] The above configurations ensure that the THz beam, regardless of the mirror position, hits the surface IP perpendicularly and, after reflection, has the same beam path in the reverse direction as the beam propagating in the forward direction.

[0049] The required resolution, in conjunction with the focal length and convergence of the principal rays, necessitates relatively large apertures and thus thick lenses. The absorption and volume scattering of these components can be reduced by Fresneling the scanner optics.

[0050] Synchronization of measurement and location data can be achieved using a software tool. The system's axis position data and the scanner's mirror position data are read and linked with the measurement data to create a 2D measurement map. From this, a modification map is derived, containing the processing instructions for selective sintering or location-selective post-treatment. The necessary set of rules is derived from process development and describes which laser parameters (e.g., power) must be used for post-treatment at which location, based on the initial conductivity value (measured value), to achieve uniform conductivity along, for example, the entire length of a conductor track. Figure 3 shows an example of the dependence of the achievable conductor resistance on the applied laser area energy.In this example, only uniformly printed traces were included in the evaluation, so the effects of printing variations were not considered. Targeted, selective post-sintering can therefore be used to equalize the resistance along the length of the trace.

[0051] Following the measurement of the local conductivity, selective laser post-treatment is performed. Areas with conductivity below a target value are selectively re-sintered, thus achieving a reproducible resistivity layer. This process and the corresponding equipment allow for the detection of local deviations in the functionality of an electrical or electronic layer—in the previous example of the strain gauge, the electrical conductivity along a conductor—and their selective adjustment via laser processing. This ensures homogeneous functionality of the layer, including, for example, homogeneous density, crystal structure, or dopant concentration. The degree of selective post-treatment—in the previous example of the printed strain gauge, the degree of sintering of the nanoparticles; in other examples, perhaps the activation of dopant particles, crystallinity, etc.—is determined by the specific properties of the layer.The deviation of the layer from the target value, measured locally, determines the parameters. One possible parameter is the power of the laser radiation used for post-processing, which can be adjusted selectively. This selective post-processing can also be used to achieve homogeneous functional properties of the layer with a specific value, e.g., with respect to electrical conductivity, or to deliberately create inhomogeneous properties, such as defined areas of different conductivity.

[0052] A significant advantage arises from the combination of the location-selective measurement method and location-selective post-treatment, enabling the simultaneous correction of local deviations in the layer's functionality (e.g., electrical conductivity or electrical resistance). A further advantage is the implementation of the measurement system in a scanning device with correspondingly high spatial (enabled by the optics) and temporal resolution (enabled by the fast measurement method of a preferred embodiment and the scanning device), while maintaining a sufficient working distance between the measurement system and the object under investigation / processed. This allows for the accurate and sufficiently fast measurement of even small or narrow structures on a 3D component, enabling a production process. The fast measurement method is based on the selection of dedicated, narrow measurement frequency bands to save measurement time.

[0053] Varying the optical path length between the mirrors and the scanner lens allows for vignetting-free scanning of arbitrarily shaped surfaces. By appropriately selecting the distances, the arrangement can also be optimized for simple, toric surfaces without dynamic path length changes.

Claims

Patent claims 1. A method for producing an electrically conductive layer of as homogeneous a quality as possible, with predetermined or defined locally varying functionality, in particular electrical conductivity, in which layer material is applied to a surface and transformed into an electrically conductive layer with higher electrical conductivity by energetic treatment, wherein the electrically conductive layer is spatially scanned with at least one THz beam of continuous or pulsed THz radiation directed onto the electrically conductive layer via a scanning device, and a spatially resolved electrical conductivity of this layer is determined from a reflectivity measurement of the THz beam at the electrically conductive layer, and wherein areas of the electrically conductive layer that exhibit an electrical conductivity below or above a predetermined target value,with at least one energetic beam to modify the electrical conductivity locally, in order to obtain the electrically conductive layer with a homogeneous, predetermined or defined locally different functionality.

2. Method according to claim 1, characterized in that the THz beam is used with continuous THz radiation of a frequency > 0.5 THz, preferably a frequency between 1 THz and 3 THz.

3. Method according to claim 1 or 2, characterized in that the reflectivity measurement is carried out coherently at fewer than 10 different THz frequencies adapted to the layer to be measured.

4. Method according to one of claims 1 to 3, characterized in that the conversion of the layer material into the electrically conductive layer with higher electrical conductivity is carried out by drying, sintering, crystallization, recrystallization, melting or chemical reaction of the layer material.

5. Method according to one of claims 1 to 4, characterized in that at least one laser beam is used as the at least one energetic beam for post-treatment.

6. Method according to one of claims 1 to 5, characterized in that the energetic treatment is carried out by the action of at least one or at least one further energetic beam, especially laser beam.

7. Method according to any one of claims 1 to 6, characterized in that the scanning device comprises at least one first and one second scanner mirror (M1, M2) for an X and a Y scan direction, two relay optics (RL1, RL2) for imaging the first scanner mirror (M1) onto the second scanner mirror (M2) and a focusing optic (FL), wherein optical path lengths between the second scanner mirror (M2) and the focusing optic (FL) and between the first and the second scanner mirror (M1, M2) are set and / or varied during scanning such that the scanning THz beam always strikes the electrically conductive layer perpendicularly, regardless of the position of the scanner mirrors (M1, M2).

8. Method according to claim 7, characterized in that a focus of the THz beam is tracked by arranging a Z-shifter optic (ZS) in the beam direction in front of the scan device or by scan-synchronous movement of the focusing optic (FL) in the Z direction so that it lies on the electrically conductive layer during the entire scanning process.

9. System for producing an electrically conductive layer that is as homogeneous as possible, predefined or defined locally different functionality, in particular electrical conductivity, which includes at least: - a device for applying a layer material to a surface to be coated, - a material processing device designed to direct at least one energetic beam over a layer material applied to the surface and / or an electrically conductive layer created on the surface in order to convert this layer material into an electrically conductive layer and / or to locally post-treat the electrically conductive layer, - a THz measuring device with a scanning device, via which a THz beam generated by the measuring device can be guided over the electrically conductive layer, and - a control device for controlling the plant according to the method according to one or more of the preceding patent claims .

10. System according to claim 9, characterized in that the scanning device comprises a galvanometer scanner.

11. System according to claim 9, characterized in that , that the scanning facility has a 2D scanner with only one mirror.

12. System according to claim 9 or 10, characterized in that the scanning device has at least one first and one second scanner mirror (M1, M2) for an X and a Y scan direction, two relay optics (RL1, RL2) for imaging the first scanner mirror (M1) onto the second scanner mirror (M2) and a focusing optic (FL), wherein the scanning device is designed such that optical path lengths between the second scanner mirror (M2) and the focusing optic (FL) and between the first and the second scanner mirror (M1, M2) can be varied before and / or during scanning.

13. System according to claim 12, characterized in that a Z-shifter optic (ZS) is arranged in the direction of the beam in front of the scanning device.

14. System according to one of claims 9 to 13, characterized in that the material processing device emits at least one laser beam as the at least one energetic beam.

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