Device for applying a material to a target substrate, method for using such a device and method for producing such a device

Abstract

The device for applying a material to a substrate comprises a source substrate having at least one recess for receiving the material and comprises at least one heating element. The heating element at least partly covers at least one base region and / or side surfaces of the recess. The heating element is electrically conductively connected to an electrical power supply. Precisely one heating element is assigned to each recess. A pattern for a micro-LED can be printed by means of the device.

Description

[0001] Description

[0002] DEVICE FOR APPLYING A MATERIAL TO A TARGET SUBSTRATE, METHOD FOR USING SUCH A DEVICE AND METHOD FOR PRODUCING SUCH A DEVICE

[0003] A device is specified, in particular a device for applying a material to a target substrate. Furthermore, a method for using such a device and a method for producing such a device are specified.

[0004] One problem to be solved is, among other things, to provide a device by means of which a plurality of different materials can be applied to a target substrate in preferably small structures. Further problems to be solved are, among other things, to provide a method for operating such a device and a method for manufacturing such a device.

[0005] These objects are achieved by a device having the features of independent patent claim 1 and by methods having the features of patent claims 12 and 16, respectively. Advantageous embodiments and further developments are the subject of the respective dependent patent claims.

[0006] According to at least one embodiment, the device comprises a source substrate with at least one recess. The recess is particularly designed to accommodate a material that is to be transferred from the source substrate to a target substrate. The material is, for example, an electrically insulating or electrically conductive material.

[0007] The material is, for example, a paste and can be applied to the recess using a doctor blade. In this case, the material can be cured. This means that after application to the target substrate, the material can be cured and solidified, for example, using thermal or chemical processes.

[0008] The material can be applied to the target substrate in a structured manner. This means, in particular, that further structuring of the material is not necessary after application to the target substrate. Preferably, a geometric shape and / or a number of recesses from which the material is detached are specified accordingly.

[0009] For example, the material is a solder paste with which structured electrical solder connections can be created on the target substrate. For example, an optoelectronic semiconductor chip can subsequently be electrically connected to the target substrate using the structures created on the target substrate.

[0010] Alternatively, the material may be, for example, a dielectric material with which structured passivation layers or other electrically insulating layers can be arranged on the target substrate.

[0011] The source substrate is preferably formed from electrically insulating materials. Preferably, the source substrate is formed from a material with comparatively poor thermal conductivity. For example, the source substrate comprises glass and / or dielectric materials such as silicon oxide.

[0012] According to at least one embodiment, the device comprises at least one heating element. The heating element is formed, in particular, from a metal and can be heated by means of an electric current. For this purpose, the heating element preferably has a comparatively high electrical resistance. A current density in the heating element is preferably comparatively high. For example, the heating element comprises platinum or is formed therefrom.

[0013] According to at least one embodiment of the device, the heating element at least partially covers at least a bottom region and / or side surfaces of the recesses. The bottom region of the recess is, for example, a surface within the recess that is formed parallel to a main extension plane of the device. Side surfaces of the recess are, for example, surfaces within the recess that run transversely or perpendicularly to the bottom region. "Covered" here and below means in particular that, viewed towards the recess, the bottom surface and / or the side surfaces are at least partially covered by the heating element. It is also possible for further layers or elements to be arranged between the heating element and the bottom region or the side surfaces of the recess.

[0014] It is possible that the bottom area is completely covered by the heating element. Alternatively or additionally, it is possible that the side surfaces are completely covered by the heating element. During operation of the device, the

[0015] Material directly borders the heating element. Alternatively, it is possible for at least one further layer to be arranged between the heating element and the material. The further layer is, for example, a protective layer and / or a non-stick layer. Preferably, at most three or at most two or exactly one further layer is / are arranged between the heating element and the material in the recess. This allows for particularly good heat transfer from the heating element to the material.

[0016] According to at least one embodiment of the device, the heating element is electrically conductively connected to an electrical power supply. The electrical power supply is, for example, an external electrical power supply. The heating element can be energized and heated by means of the electrical power supply. For example, the heating element is electrically connected to the external power supply by means of one or more conductor tracks, which can be located at least partially within the source substrate.

[0017] According to at least one embodiment of the device, exactly one heating element is assigned to each recess. This means in particular that in the case of multiple recesses, the device comprises the same number of heating elements. For example, exactly one heating element can be arranged in each recess. Alternatively, it is also possible for the heating elements to be arranged in an assembly of heating elements. In this case, the heating elements can be connected to one another. For example, the heating elements can be present in one piece in the assembly. A heating element is then formed in particular by a region of the assembly of heating elements that is arranged in the associated recess.

[0018] In at least one embodiment, a device for applying a material to a target substrate comprises a source substrate with at least one recess for receiving the material and at least one heating element. The heating element at least partially covers at least a bottom region and / or side surfaces of the recess. The heating element is electrically conductively connected to an electrical power supply. Exactly one heating element is assigned to each recess.

[0019] The device described here is based on the following technical considerations. Conventional methods for applying pastes to a target substrate include screen and stencil printing, jetting and spindle dispensing techniques, inkjetting, electrohydrodynamic dispensing (EHD) and ultra-precision dispensing (UPD), aerosol jetting, offset printing, and lithographic processes.

[0020] Furthermore, pastes can be transferred to a target substrate using lasers. Known processes include laser-assisted transfer, also known as laser-induced forward transfer (LIFT), or volumetric controlled laser printing (VCLP).

[0021] In these laser-assisted processes, a cavity is typically formed in a substrate, which is then coated with a release layer. Laser irradiation heats the release layer, causing a paste disposed in the cavity to vaporize at a boundary between the release layer and the cavity. The resulting gas forces the paste out of the cavity and allows it to be transferred to a target substrate.

[0022] With the methods mentioned above, the paste can usually only be applied to the target substrate in small structures. Laser-assisted transfer methods also require a comparatively expensive laser source, which must also be precisely aligned. This increases the effort and costs, especially for small structures to be transferred.

[0023] The device described here utilizes the idea of ​​providing a heating element, particularly an electric one, in the recess, which can be heated by means of an electric current. In other words, Joule heat is generated by the heating element. Due to the heating of the heating element, a material arranged in the recess can be vaporized in a border region to the heating element during operation of the device. This allows the material to be released from the recess and transferred to the target substrate.

[0024] Advantageously, this makes it possible to dispense with a laser source or the like. This eliminates the need for optical alignment. Furthermore, power sources for heating elements are typically cheaper than laser sources. Overall, the device described here reduces the effort and cost of transferring material to the target substrate. Furthermore, the transfer can be carried out relatively quickly, which can further reduce costs. Furthermore, a number of recesses can be made in the source substrate, each of which can be assigned a heating element. If these heating elements are individually controlled during operation, predefined print patterns can be transferred quickly and cost-effectively. The device described here can therefore advantageously be used flexibly.

[0025] In the source substrate, the recesses can be formed, for example, to be comparatively small and flat, in particular by means of etching. This allows small structures of the material on the target substrate after transfer. A depth of the recesses, in particular measured perpendicular to a bottom region of the recess, is, for example, between 1 pm and 1 mm inclusive, preferably between 2 pm and 20 pm inclusive. A width of the recess, in particular measured parallel to the bottom region, is, for example, between 1 pm and 10 mm inclusive, preferably between 10 pm and 100 pm inclusive.

[0026] According to at least one embodiment of the device, it further comprises at least one column line and at least one row line. The column line and the row line are electrically conductively connected to one another via the heating element. The column line and the row line are preferably each electrically conductively connected to the electrical power supply. During normal operation of the device, the heating element can be energized via the column line and row line in order to heat the material in the recess.

[0027] The column line and row line are formed in particular with a metal such as copper. According to at least one embodiment of the device, it has a plurality of heating elements, a plurality of column lines, and a plurality of row lines. In particular, the column lines and the row lines can each be energized independently of one another. Preferably, each of the heating elements is electrically conductively connected to exactly one column line and exactly one row line. At the same time, it is possible for each column line and / or each row line to be connected to a plurality of heating elements.

[0028] Advantageously, this makes it possible, during normal operation, to control and operate each heating element individually and independently of the other heating elements. This means that a pixelated transfer of the material from the source substrate to the target substrate is possible. If, for example, a certain predetermined number of heating elements is to be activated so that a specific pattern or structure of the material is to be applied to the substrate, the correspondingly assigned column lines and row lines can be energized. This allows for flexible and variable operation of the device described here.

[0029] According to at least one embodiment, it is possible for the plurality of heating elements to be formed as a continuous layer comprising a plurality of heating elements in a composite. In this case, the composite of heating elements can extend over a plurality of or all of the recesses. In such a case, pixelated transfer of the material is also possible. A heating element is then, in particular, a region of the composite that is arranged in an associated recess. The resistance of each heating element must be much higher than the resistance of the column and row lines. If, during operation, only one pair of column and row lines is energized, the current flows directly via the smallest resistance, even if the heating element is a continuous layer. This advantageously also allows pixelated transfer to take place.

[0030] If multiple pixels are to be powered simultaneously during operation or if leakage currents are to be reduced, it may be advantageous to split the heating element assembly into several heating elements. This advantageously reduces leakage currents when powering the heating elements.

[0031] According to at least one embodiment of the device, the column lines are formed as parallel first strips and the row lines as parallel second strips. A main extension direction of the first strips is perpendicular to a main extension direction of the second strips. The strips have a uniformly small thickness. The thickness is measured, for example, perpendicular to the main extension direction. The thickness of the first and second strips is, for example, less than 60 pm or less than 40 pm or preferably less than 20 pm.

[0032] In particular, the first and second strips form a grid, in particular a uniform rectangular grid, when projected onto a plane parallel to the main extension plane of the device. The first and second strips can in particular be arranged in different planes of the device. For example, a recess is arranged in overlapping regions of the first and second strips. The overlapping regions are arranged, for example, at the nodes of the grid. For example, the first and / or second strips have a cutout in the overlapping regions. The first and / or second strips can therefore be formed in a multiply connected manner. A recess with a heating element is preferably arranged in the cutout.The heating element electrically connects a specific first strip associated with the overlay region to a specific second strip associated with the overlay region.

[0033] By arranging the column lines and row lines as first and second strips that run perpendicular to each other, a so-called cross-matrix control of the device is possible.

[0034] According to at least one embodiment of the device, the source substrate has a carrier and an electrical insulator. The electrical insulator is arranged on a first main surface of the carrier. In particular, the at least one column line is arranged between the carrier and the electrical insulator. The recess preferably penetrates the electrical insulator completely. The electrical insulator can also be referred to simply as "insulator" hereinafter. This means in particular that if an element is referred to as "insulator" hereinafter, it is in particular an electrical insulator, unless stated otherwise.

[0035] The carrier of the source substrate is preferably formed from an electrically insulating and thermally poorly conductive material. The carrier is formed, for example, from glass. The insulator is preferably formed from an electrically insulating material. The insulator is formed, for example, from a dielectric material such as silicon oxide. Such a dielectric material can advantageously be structured to create the recesses in the insulator.

[0036] The recess preferably penetrates the insulator completely, so that, in particular, the recess forms a hole or opening in the insulator. In particular, the bottom region of the recess is free of the insulator.

[0037] The carrier has, for example, a thickness, in particular measured perpendicular to a main extension direction of the device or of the carrier, of less than 500 pm or less than 400 pm.

[0038] According to at least one embodiment of the device, it further comprises a connection region for connecting the external power supply to the column line and / or row line. In the connection region, the source substrate is free of the insulator. In the connection region, in particular, the heating element can be connected to the electrical power supply, for example, during operation of the device.

[0039] In the connection area, for example, the column line and / or row line is accessible. For example, the column line and / or row line can be electrically contacted in the connection area by means of a solder connection. It is possible for the connection area to be arranged in a further recess. In this case, the further recess is preferably free of a heating element and serves, for example, merely for electrically contacting the column line and / or row line.

[0040] According to at least one embodiment of the device, the carrier of the source substrate has a smaller thickness in the connection region than outside the connection region. Advantageously, with a reduced thickness in the connection region, the device can be electrically contacted particularly easily. This advantageously eliminates the need for a relatively complex and expensive through-hole plating through the carrier. Likewise, in this case, no side metallization of the carrier is advantageously necessary.

[0041] According to at least one embodiment of the device, the at least one row line is arranged on a side of the insulator facing away from the first main surface of the carrier. In particular, the insulator is flush with the row line in a direction away from the carrier. The side of the insulator facing away from the first main surface of the carrier can also be referred to here and below as the front side of the device or the front side of the source substrate.

[0042] In particular, the row line is attached to the front side. The row line can be accessible from the front side. It is also possible for the row line to be buried in the insulator and not freely accessible at the front side. Alternatively or additionally, the electrical insulator can terminate at the connection area in a direction parallel to the first main surface. This means, in particular, that the insulator can reach as far as the connection area from the direction of the recess.

[0043] According to at least one embodiment of the device, the at least one row line is arranged on a rear side of the source substrate and is electrically conductively connected to the heating element via a via through the source substrate. The rear side of the source substrate is, in particular, opposite the front side. For example, the rear side of the source substrate is formed by a second main surface of the carrier, which is opposite the first main surface.

[0044] Alternatively or additionally, it is possible for the column line to be arranged on the back of the source substrate. In this case, the column line is also connected to the heating element via vias. Furthermore, in this case, the row lines can be electrically separated from the column lines by means of an electrical insulating layer.

[0045] By arranging the row line and / or the column line on the back of the source substrate, the row line and / or the column line can advantageously be electrically contacted particularly easily.

[0046] The via is formed, for example, with the same material as the row line and / or column line. In particular, the via comprises copper. A width of the via, in particular measured parallel to the main extension plane of the device, is, for example, at least 30 pm or at least 80 pm and / or at most 100 pm.

[0047] According to at least one embodiment of the device, the heating element comprises a first layer and a second layer that are electrically conductively connected to one another. The first layer at least partially covers at least the bottom region of the recess, and the second layer at least partially covers at least the side surfaces of the recess.

[0048] It is possible, for example, for the column line and / or the row line to have a hole in the region of the bottom region of the recess. In other words, the bottom region of the recess is free of the column line and / or row line. The first layer of the heating element is then arranged at the bottom region, preferably bridging the hole and being electrically conductively connected to the column line or the row line. The first layer is then electrically conductively connected, in particular directly connected, to the second layer, which at least partially covers the side surfaces of the recess.

[0049] Alternatively, it is possible for the first layer and the second layer to be in contact with each other in the bottom area. In this case, the second layer also covers the bottom area of ​​the recess at least partially.

[0050] During device manufacture, the first layer is preferably applied to the carrier before the insulator. This application can occur before or after the column lines are applied. Applying the first layer before the insulator allows for particularly simple structuring of the first layer, as complex structuring within the recesses is eliminated.

[0051] The first layer and the second layer are each formed with a metal, for example. For example, the first and second layers each comprise platinum.

[0052] Comparatively, a layered heating element structure allows for higher current densities and thus greater heating of the heating element. Particularly in the base area, a two-layer heating element allows for greater heating and thus better material removal during normal operation of the device.

[0053] According to one embodiment of the device, the heating element is at least partially covered by a protective layer. The protective layer is arranged, for example, in the recess. However, it is possible for the protective layer to protrude beyond the recess and completely or partially cover the front side.

[0054] The protective layer is formed, for example, with molybdenum, tungsten, silicon oxide, silicon nitride, tungsten carbide, Al2O3 or diamond.

[0055] The protective layer advantageously protects the heating element during operation when the material is introduced. Material can be introduced, for example, by doctoring. The protective layer can therefore reduce or prevent scratching of the heating element during doctoring. Preferably, the protective layer also has non-stick properties. The protective layer is, for example, a non-stick layer. This advantageously allows the material to be transferred to the substrate particularly easily during operation of the device.

[0056] More preferably, the protective layer is formed from an electrically insulating material. This avoids an electrical connection between an electrically conductive material, which is to be transferred to the target substrate during operation of the device, and the heating element.

[0057] According to at least one embodiment of the device, the source substrate is arranged on a roll. The source substrate has at least one functional unit, each of which has a plurality of recesses and at least one connection region. A heating element is assigned to each of the recesses. In the connection regions, the functional unit and the heating elements can be electrically contacted or energized, for example by means of a contact needle.

[0058] In this embodiment, the device can be rotated during normal operation. The at least one functional unit can be rotated. During rotation, the recesses of the functional unit can be filled with the material to be transferred to the target substrate. For example, a doctor blade can be used for this purpose.

[0059] Furthermore, the role is designed to ensure the functional

[0060] unit to continue rotating. This will ensure the functional

[0061] The unit is preferably positioned and aligned over the target substrate. Alignment can be performed precisely using an alignment camera. In particular, the material is then applied to the target substrate. For this purpose, the heating elements are energized using contact needles.

[0062] After further rotation, the functional unit can optionally be cleaned and material can be taken up again by further rotation of the roll.

[0063] It is also possible for the device to be planar, unlike a rotating device. In this case, it is not mounted on a roller, but on a planar plate or the like. It is possible for the source substrate to have multiple functional units.

[0064] By arranging one or more functional units, each with one or preferably several recesses, the material can be applied to the target substrate in a structured manner during operation. For example, a position of the functional units on the plate can be adjusted for this purpose. Advantageously, such a planar device can be used to create a multitude of material structures on the target substrate in a single process step in which the material is transferred to the target substrate.

[0065] Furthermore, the at least one functional unit can be cleaned after application of the material. For this purpose, a cleaning device such as a nozzle and a collecting tray can be provided.

[0066] For precise positioning of the source substrate with respect to the

[0067] An alignment camera can be used to precisely apply the material to the target substrate.

[0068] In the case of a planar device, the heating elements can advantageously be supplied with current via supply lines during normal operation. This means that the application of contact needles or the like is not necessary.

[0069] Furthermore, a method for using a device described here is described. In particular, the method can be used with a device described here. This means that all features disclosed for the method for using the device are also disclosed for the device, and vice versa.

[0070] The method for using the device comprises a method step in which the material is introduced into the recess. Subsequently, an electric current is applied to the heating element, so that the heating element is heated. Subsequently, the material evaporates in a region adjacent to the heating element. In particular, a gas is formed in the process. Subsequently, the material is detached from the source substrate and applied to the target substrate.

[0071] The electrical current is applied, for example, as a current pulse. In particular, the current pulse is applied to the at least one column line and the at least one row line. For example, the recesses or the heating element in the recesses can each have a thermal resistance of 1000 K / W. If such a heating element is to be heated by 100 K during operation, this requires in particular 0.1 W. If an electrical resistance of the heating element is, for example, 1 Q and an applied voltage is 1 V, the current intensity in the heating element in the example is 0.1 A. The thermal resistance and the electrical resistance can be adapted by selecting the material, material thicknesses and geometries.

[0072] According to at least one embodiment, the material is introduced into the recess by doctoring. In this case, the material is preferably a paste. The paste can be cured, for example, after being applied to the target substrate.

[0073] According to at least one embodiment, the electric current or current pulse is applied to the heating element by means of at least one contact needle. For example, the contact needle is applied to the column line and / or the row line in a connection region.

[0074] Alternatively, it is possible for the current source to be permanently connected to the column line and / or the row line. For example, the current source is electrically connected to the column line and / or the row line via a solder connection in the connection area.

[0075] According to at least one embodiment of the method for using the device, the recess is cleaned after the material has been removed from the source substrate. Preferably, the entire source substrate is cleaned. After cleaning, the device can be used again to transfer a material from the source substrate to a target substrate. According to at least one embodiment of the method for using the device, a structure for a micro-LED is printed by means of the method.

[0076] As a broad definition, a micro-LED could be seen as any light-emitting diode (abbreviated to "LED") - generally not lasers - with a particularly small size.

[0077] As a rule - this is also a very important criterion besides the size - a growth substrate is removed from micro-LEDs, so that typical heights of such micro-LEDs are, for example, in the range of 1.5 pm to 10 pm.

[0078] In principle, a micro-LED does not necessarily have to have a rectangular radiation emission area. For example, an LED could generally have a radiation emission area such that, viewed from above onto the layers of the stack, each lateral dimension of the radiation emission area is less than or equal to 100 pm or less than or equal to 70 pm.

[0079] For example, for rectangular micro-LEDs, an edge length - especially in plan view of the layers of the layer stack - of less than or equal to 70 pm or less than or equal to 50 pm is often cited as a criterion.

[0080] Such micro-LEDs are usually provided on wafers with holding structures that can be removed without damaging the pLED.

[0081] Micro-LEDs are currently mainly used in

[0082] Displays are being considered. Micro-LEDs form pixels or subpixels and emit light of a defined color. Due to their small pixel size and high density with close spacing, micro-LEDs are suitable for small, monolithic displays for AR applications, particularly data glasses. In addition, work is underway on other applications, particularly data communication and pixelated lighting applications.

[0083] In the literature you can find different notations for micro-LEDs, e.g. pLED, p-LED, uLED, u-LED or Micro Light Emitting Diode.

[0084] Furthermore, a method for producing a device described here is described. In particular, a device described here can be produced using the method. This means that all features disclosed for the method for using the device are also disclosed for the device, and vice versa.

[0085] In at least one embodiment, the method comprises structuring a carrier. For example, a connection region is formed in the carrier. Furthermore, it is possible for the carrier to be prepared on a first main surface to facilitate further processing of the carrier. For example, the carrier can be roughened on the first main surface.

[0086] Subsequently, at least one column line is applied to the first main surface of the carrier. The column line is deposited, for example. The column line can be structured, for example, to form first stripes. It is possible for a material of the column line to first be deposited flatly on the first main surface of the carrier and subsequently structured to form the at least one column line.

[0087] Subsequently, an insulator is arranged on a side of the column line facing away from the first main side of the carrier and / or on the first main side of the carrier. The insulator is formed, for example, with a dielectric. The insulator is deposited, for example.

[0088] The insulator is then structured to form at least one recess. For example, the at least one recess is etched. The recess can be created using a lithography method. The recess can be made particularly flat and / or narrow. This allows particularly small structures to be transferred from the device to the target substrate.

[0089] For example, the insulator in the area of ​​the cutout is completely removed. In this case, the cutout completely penetrates the insulator.

[0090] Subsequently, at least one heating element is arranged on the bottom region and / or side surfaces of the recess, so that the heating element is electrically conductively connected to the column line. The heating element is deposited, for example. The heating element can subsequently be structured, for example, using a lithography method.

[0091] For example, a material for the heating element is deposited flatly on a side of the insulator facing away from the carrier and then structured. Preferably, after structuring, each recess is assigned exactly one heating element. In this case, several column lines are preferably formed. Then, each of the heating elements is preferably electrically connected to exactly one column line.

[0092] Subsequently, at least one row line is applied so that the heating element is electrically conductively connected to the row line. If multiple recesses are formed in the insulator, preferably multiple row lines are also formed. In particular, each heating element is electrically conductively connected to exactly one row line.

[0093] The row line is applied, for example, by deposition. For example, a material for the row line is deposited over a large area and then structured, for example, using a lithography method.

[0094] According to at least one embodiment of the method for manufacturing a device, the row line is arranged on a side of the insulator facing away from the first main side of the carrier. For example, several row lines are applied, which are subsequently structured into second strips.

[0095] According to at least one embodiment, the row line is arranged on a second main surface of the carrier opposite the first main surface. Furthermore, a through-hole is formed through the carrier, which connects the row line to the heating element in an electrically conductive manner. Further advantages and advantageous embodiments and developments of the device described here and the method for using the device as well as the method for producing the device emerge from the exemplary embodiments presented below in conjunction with schematic drawings. Identical, similar and equivalent elements are provided with the same reference numerals in the figures. The figures and the proportions of the elements shown in the figures to one another are not generally to scale.Rather, individual elements may be shown in an exaggerated size for better presentation and / or understanding.

[0096] It shows :

[0097] Figures 1 and 2 are schematic views of a device described here according to a first embodiment,

[0098] Figures 3 to 6 are schematic sectional views of various embodiments of a device described here,

[0099] Figures 7 to 9 show various process stages of a process for using a device described here according to an embodiment,

[0100] Figures 10 to 15 show various process stages of a process for producing a device described here according to an embodiment, Figures 16 and 17 show schematic representations of a device described here according to a further embodiment,

[0101] Figures 18 and 19 are schematic representations of a device described here according to a further embodiment,

[0102] Figure 20 is a schematic representation of a device described here according to a further embodiment.

[0103] Figure 1 shows a sectional view of a device 1 described here according to a first exemplary embodiment. The sectional plane is perpendicular to a main extension plane of the device. The device 1 for applying a material to a target substrate according to Figure 1 comprises a source substrate 2. The source substrate 2 comprises a carrier 21 and an insulator 22. A plurality of recesses 3 are made in the insulator 22 and completely penetrate the insulator 22 in a direction perpendicular to the main extension direction of the device 1. The recesses 3 are designed to receive a material 100 that is to be transferred to a target substrate 200 (Figure 7). The carrier 21 is formed from glass in the present exemplary embodiment. The insulator 22 is formed from silicon oxide in the present exemplary embodiment.

[0104] A plurality of column lines 5 are arranged between the carrier 21 and the insulator 22. In the sectional view of Figure 1, the sectional plane runs through one of these column lines 5. The column lines 5 are each formed from an electrically conductive material such as a metal. In the present embodiment, the column lines 5 are formed from copper.

[0105] On a side of the insulator 22 facing away from the carrier 21, which side forms a front side 12 of the device 1, row lines 6 are arranged outside the recesses 3. The row lines 6 each have a hole in the region of the recesses 3, in which hole the corresponding recess 3 is exposed. Therefore, in the sectional view of Figure 1, a row line 6 can be seen on both sides of an associated recess 3. The row lines 6 are preferably formed from the same material as the column lines 5.

[0106] The column lines 5 and row lines 6 are electrically conductively connected to one another via a plurality of heating elements 4. Each recess 3 is preferably assigned precisely one heating element 4. Each of the heating elements 4 is preferably a metal and, in the present exemplary embodiment, is formed from platinum. Each heating element 4 preferably connects precisely one column line 5 to one row line 6. The heating elements 4 are, in particular, designed as a composite, with the individual heating elements 4 being interconnected in the composite.

[0107] The source substrate 2 further comprises a connection region 7, in which each of the column lines 5 is electrically conductively connected to a power supply 10. For example, each of the column lines 5 is electrically conductively connected to the power supply 10 with a solder 11. In the connection region 7, the carrier 21 has a smaller thickness than outside the connection region 7. Furthermore, in the connection region 7, the carrier 21 is free of the insulator 22.

[0108] It is also possible for the source substrate 2 to comprise a further connection region (not shown) having substantially the same features as the connection region 7. In the further connection region, the row lines 6 are electrically conductively connected to the power supply 10.

[0109] Figure 2 shows the device 1 according to the first exemplary embodiment viewed from the front side 12. As can be seen in the view shown in Figure 2, the device 1 has a plurality of column lines 5 arranged in first strips 50. Furthermore, the device 1 has a plurality of row lines 6 arranged in second strips 60. This means, in particular, that a thickness of the strips 50 / 60, measured perpendicular to the main extension direction, is smaller than their length and / or width. The column lines 5 and row lines 6 each have a thickness of 18 pm, for example. The heating elements 4 each have a thickness of 100 nm, for example.

[0110] The first strips 50 and the second strips 60 form a regular grid in a projection onto the front side 12. The recesses 3 are provided in overlapping regions 40 of the first strips 50 and the second strips 60, which are arranged at nodes of this grid. The heating elements 4 can therefore be seen in the transition regions 40. Due to the grid-like arrangement of the column lines 5 and row lines 6, precisely one specific heating element 4 or several specific heating elements 4 can be operated during intended operation by means of the power supply 10 and targeted control of the associated column lines 5 and row lines 6.

[0111] Figure 3 shows the device 1 according to a second exemplary embodiment. The second exemplary embodiment differs from the first exemplary embodiment in particular in that the heating element 4 comprises a first layer 41 and a second layer 42. The first layer 41 covers the bottom region 30 of the recess 3, and the second layer 42 at least partially covers the bottom region 30 and side surfaces 31 of the recess 3. The first layer 41 and the second layer 42 are electrically conductively connected to one another in the bottom region 30. In the present exemplary embodiment, the first layer 41 and the second layer 42 are each formed with platinum.

[0112] In the region of the recesses 3, the column lines 5 have holes that are bridged by the first layer 41. If a current is applied to the column lines 5 during normal operation, the first layer 41 has a higher current density than the column lines 5. This allows the first layer 41, and thus the heating element 4, to be heated particularly effectively.

[0113] During the manufacture of the device 1, the first layer 41 is preferably applied to the carrier 21 before the insulator 22. This application can take place before or after the application of the column lines 5. Because the first layer 41 is applied before the insulator 22, the first layer 41 can be structured particularly easily, since complex structuring within the recesses 3 is eliminated.

[0114] In other features, the first and second embodiments are essentially identical.

[0115] Figure 4 shows the device 1 according to a third exemplary embodiment. The third exemplary embodiment has essentially the same features as the second exemplary embodiment, with the difference that the base region 30 is essentially free of the second layer 42. The second layer 42 is arranged only at the edge of the base region 30 in order to enable an electrically conductive connection to the first layer 41. Compared to the second exemplary embodiment, the current density in the base region 30 can thus be further increased; this enables, among other things, more homogeneous and more efficient heating of the heating element 4 in the base region 30.

[0116] Figure 5 shows the device 1 according to a fourth exemplary embodiment, which differs from the third exemplary embodiment in particular in that the first layer 41 is removed in a central region of the base region 30, so that in this region the base region 30 is essentially covered by the second layer 42. The first layer is arranged only at the edge of the base region 30 in order to enable an electrically conductive connection to the column line 5.

[0117] An arrangement of the first and second layers 41, 42 of the heating element 4 can be applied analogously to all other embodiments. Figure 5 further illustrates that on the front side 12, the insulator 22 is flush with the row line 6. This means that outside the recesses 3, the insulator 22 has a thickness such that the row line 6 does not protrude beyond the insulator. This protects the row line 6 from external influences.

[0118] Furthermore, Figure 5 illustrates that a heating element 4 is arranged in each recess 3. This means that the heating element 4 is not designed as a continuous composite that extends over several recesses 3. Each of the heating elements 4 is electrically conductively connected to at least one row line 6 and one column line 5. This allows the device 1 to be operated in a pixelated manner, with each of the recesses 3 forming a pixel. This means in particular that each recess 3 or each heating element 4 can be controlled and operated individually and independently of the other recesses 3 or heating elements 4. Thus, the material 100 can be selectively applied to the target substrate 200 in a pattern or the like using the device 1.

[0119] If several pixels are to be powered simultaneously or leakage currents are to be reduced during operation, it may be advantageous to split a group of heating elements 4 into several heating elements 4.

[0120] A separation of the heating element 4 into a plurality of heating elements 4, wherein a heating element 4 is arranged in each recess 3, so that the heating element 4 does not extend as a continuous element over several or all recesses 3, can be present accordingly in all embodiments. Figure 6 shows the device 1 according to a fifth embodiment. The fifth embodiment has essentially the same features as the fourth embodiment, with the difference that a protective layer 8 is applied to the front side 12. The protective layer 8 is formed, for example, with molybdenum, tungsten, silicon oxide, silicon nitride, tungsten carbide, Al2O3 and / or diamond. The protective layer 8 protects the heating element 4 and / or the insulator 22 and / or the row line 6, for example, from damage, such as scratching, when the material 100 is introduced into the recesses 3.For example, the material 100 is introduced into the recesses 3 by means of a doctor blade, whereby the front side 12 can be slightly shortened (Figure 7).

[0121] The protective layer 8 can also have a non-stick effect. This means that the protective layer 8 can reduce adhesion between the material 100 and the source substrate 2, so that the latter can be more easily removed from the recesses 3 and transferred to the target substrate 200.

[0122] The embodiment of Figure 6 further differs from the embodiment of Figure 5 in that the row lines 6 are buried or embedded in the insulator 22. This means, in particular, that the row lines 6 are not accessible from the outside, in particular from the front side 12.

[0123] A protective layer 8, as explained in connection with Figure 6, can also be present in all other embodiments of the device 1. In the method for using a device 1 described here, a material 100, which is to be transferred from the substrate 2 to a target substrate 200, is introduced into recesses 3 of the source substrate 2 in one method step (Figure 7). The device 1 is the device 1 of the first embodiment. In the embodiment of Figures 7 to 9, the material 100 is introduced into the recesses 3 using a doctor blade 72.

[0124] The material 100 is a paste, for example, a solder paste. The solder paste can be used, for example, to apply a solder structure to the target substrate 200. For this purpose, the solder paste can be cured or solidified on the target substrate 200.

[0125] In a subsequent method step, a current pulse 9, illustrated by the arrows in Figure 8, is applied to the row lines 6 and column lines 5 via the power supply 10. The resistance of the heating element 4 is preferably much higher than the resistance of the column and row lines 5, 6. If only one pair of column and row lines 5, 6 is energized, the current flows directly through the smallest resistance, even if the heating element 4 is a continuous layer.

[0126] Due to the current pulse 9 and the resulting current flow through the column lines 5, the row lines 6, and the heating elements 4, the heating elements 4 heat up. This heating results in a partial evaporation of the material 100 in a region adjacent to the heating element 4. During the evaporation, gas is formed, which pushes the material 100 out of the recesses 3. Thus, the material 100 can be released from the recesses 3 and transferred to the target substrate 200 (Figure 9).

[0127] By arranging the column lines 5 and row lines 6 in a grid-like manner (Figure 2), all heating elements 4 can be controlled and operated independently of one another and individually. This allows a predetermined pattern or structure of the material 100 to be applied to the target substrate 200. For example, an electrical contact structure for a micro-LED can be applied to the target substrate 200.

[0128] In the exemplary embodiment of the method for producing a device 1 described here, a carrier 21 is structured in a first method step (Figure 10). The method of the exemplary embodiment produces, in particular, a device 1 according to Figure 1. The carrier 21 is etched or ground, for example. By structuring the carrier 21, the connection region 7 is defined, for example.

[0129] In a further method step, the column lines 5 are applied (Figure 11). The material for the column lines 5 is deposited, for example. In particular, the material for the column lines 5 is deposited flatly on the carrier 21. After deposition, the material is structured to form the column lines 5, for example by means of a lithography method. The first stripes 50 are produced by structuring the column lines 5.

[0130] In a further method step, the insulator 22 is applied to the carrier 21 (Figure 12). The insulator 22 is preferably applied on the same side as the column lines 5. The material of the insulator 22, which is a dielectric, is deposited and subsequently patterned, for example, using a lithography method. The patterning creates the recesses 3 in the insulator 22.

[0131] In a further method step, the heating elements 4 are applied to the insulator 22 (Figure 13). The heating elements 4 are applied to a side of the insulator 22 facing away from the carrier 21. The material for the heating elements 4 is preferably deposited flatly on this side. Subsequently, the material for the heating elements 4 can be structured so that the heating elements 4 each at least partially cover a base region 30 and side surfaces 31 of a recess 3. The heating elements 4 are applied such that they are electrically conductively connected to the column lines 5.

[0132] In a further method step, the row lines 6 are applied to the insulator 22 (Figure 14). The row lines 6 are applied outside the recesses 3 on a side of the insulator 22 facing away from the carrier 21. The row lines 6 are applied in such a way that they are electrically conductively connected to the heating elements 4, so that an electrically conductive connection is established between a row line 6 and a column line 5 via each heating element 4.

[0133] In a further process step, the

[0134] The power supply 10 is electrically connected to the connection area 7. The power supply 10 is brought into electrical contact with the column lines 5 and the row lines 6 (not shown) via a solder 11. In particular, in this method step, the device 1 according to the first embodiment (Figures 1 and 2) is completed.

[0135] Figure 16 illustrates, in a detailed view, an alternative contact for the row lines 6. The row lines 6 are arranged on a rear side 13 opposite the front side 12. The row line 6 shown in Figure 16 is connected to the associated heating element 4 via a through-plating 25. The through-plating 25 is covered by the insulator 22 when viewed from the front side 12. The through-plating 25 connects the rear side 13 to a first main surface 23 of the carrier 21. The insulator 22 is arranged on the first main surface 23.

[0136] The carrier 21 has, for example, a thickness, measured between the first main surface 23 and the rear side 13, of 380 pm. The through-plating 25 has, for example, a width of at least 30 pm or 80 pm.

[0137] At the first main surface 23, the through-hole 25 is electrically connected to the heating element 4. The heating element 4 is guided along the first main surface 23 and extends into the recess 3.

[0138] Furthermore, the heating element 4 is electrically conductively connected to a column line 5, as illustrated in Figure 17. Figure 17 shows a section through the device 1 according to Figure 16, wherein the sectional plane is the first main surface 23. The column line 5 is arranged, for example, as illustrated in Figures 1 to 6. The device according to Figures 16 and 17 otherwise has essentially the same features as the device 1 according to the first exemplary embodiment.

[0139] Figures 18 and 19 illustrate a further attractive embodiment of the heating elements 4. Figure 18 shows a sectional view of the device along the first main surface 23 of the carrier 21. In contrast to Figures 16 and 17, the recess 3 is not arranged between the column line 5 and the row line 6 along the heating element 4, but rather above the column line 5 when viewed onto the front side 12. The row line 6 is in turn arranged on the rear side 13 (not shown) and is electrically conductively connected to the heating element 4 by a through-contact 25.

[0140] Figure 19 shows a section along the section line AA, which is illustrated in Figure 18. As can be seen in Figure 19, the recess 3 extends from the front side 12 to the column line 5.

[0141] Figure 20 shows a device 1 described here according to a further exemplary embodiment. A source substrate 2 is applied to a roll 70. The source substrate 2 has a plurality of functional units 77, each of which is formed from a plurality of recesses 3 in which heating elements 4 are arranged, and at least two connection regions 7. Each functional unit is designed such that a current pulse can be applied in the connection regions 7, so that at least one of the heating elements 4 can be heated. During normal operation, the recesses 3 can thus be filled with a material 100 that is to be transferred to a target substrate 200. By applying a current pulse 9 to the connection regions 7, the material 100 can be released from the recesses 3 by heating the heating elements 4.That is to say, the mode of operation of each functional unit is, for example, as explained in connection with Figures 1 and 2.

[0142] During normal operation, the roller 70 rotates along a rotation direction 76. As a result of the rotation of the roller 70, the functional units 77 pass a doctor blade 72, with which the material 100 is introduced into the recesses 3.

[0143] Subsequently, the roller 70 can be rotated further, and the functional unit 77, which is filled with the material, is positioned over a target substrate 200. Using an alignment camera 75, the functional unit 77 can be precisely positioned relative to the target substrate 200.

[0144] Subsequently, a current pulse 9 is applied to the functional unit 77 via contact needles 71, whereby the material 100 is transferred to the target substrate 200.

[0145] The functional unit is subsequently cleaned by a cleaning device 74, particularly after a further rotation of the roller 70. The cleaning device 74 comprises, for example, a nozzle with which a cleaning liquid, for example water, can be sprayed onto the source substrate. Residues of the material 100, which are thereby flushed out of the recesses 3, can be collected in a collecting tray 73.

[0146] Subsequently, the functional unit 77 can be reused to apply material 100 to the target substrate 200. For this purpose, the functional unit 77 is rotated again to the doctor blade 72.

[0147] Meanwhile, the target substrate 200 is moved in a feed direction 201 in order to provide further areas of the target substrate 200 with the material 100.

[0148] The invention is not limited to the embodiments by the description. Rather, the invention encompasses any novel feature and any combination of features, including, in particular, any combination of features in the patent claims, even if this feature or combination itself is not explicitly stated in the patent claims or embodiments.

[0149] This patent application claims priority from German patent application 10 2023 134 256.8, the disclosure of which is hereby incorporated by reference.

[0150] Reference symbol list

[0151] 1 device

[0152] 2 Source substrate

[0153] 3 recess

[0154] 4 Heating element

[0155] 5 column line

[0156] 6 line line

[0157] 7 Connection area

[0158] 8 protective layer

[0159] 9 current pulse

[0160] 10 Power supply

[0161] 11 lots

[0162] 12 Front

[0163] 13 Back

[0164] 20 Back of the source substrate

[0165] 21 carriers

[0166] 22 electrical insulator

[0167] 23 first main surface of the support

[0168] 24 second main surface of the carrier

[0169] 25 vias

[0170] 30 Bottom area of ​​the recess

[0171] 31 Side surface of the recess

[0172] 40 Overlay area

[0173] 41 first layer of the heating element

[0174] 42 second layer of the heating element

[0175] 50 first stripes

[0176] 60 second stripes

[0177] 70 rolls

[0178] 71 Contact needle

[0179] 72 squeegees

[0180] 73 On drip tray

[0181] 74 Cleaning device 75 Adjustment camera

[0182] 76 Direction of rotation

[0183] 77 functional unit

[0184] 100 Material 200 Target substrate

[0185] 201 Feed direction

[0186] AA cutting line

Claims

Patent claims 1. Device (1) for applying a material (100) to a target substrate (200), comprising: - a source substrate (2) with at least one recess (3) for receiving the material (100), - at least one heating element (4), and - at least one column line (5) and at least one row line (6), wherein - the heating element (4) at least partially covers at least one bottom region (30) and / or side surfaces (31) of the recess (3), - the heating element (4) is electrically conductively connected to an electrical power supply (10) - each recess (3) is assigned exactly one heating element (4), - the column line (5) and the row line (6) are electrically conductively connected to each other via the heating element (4), - the column line (5) and the row line (6) are each electrically conductively connected to the electrical power supply (10).

2. Device (1) according to claim 1, comprising a plurality of heating elements (4), a plurality of column lines (5) and a plurality of row lines (6), wherein - the column lines (5) and the row lines (6) can each be energized independently of each other and - each of the heating elements (4) is electrically conductively connected to exactly one of the column lines (5) and exactly one of the row lines (6).

3. Device (1) according to claim 1 or 2, wherein - the column lines (5) are designed as parallel first strips (50), - the row lines (6) are designed as parallel second strips (60), - a main extension direction of the first strips (50) is perpendicular to a main extension direction of the second strips (60).

4. Device (1) according to one of the preceding claims, wherein - the source substrate (2) comprises a carrier (21) and an electrical insulator (22), - the electrical insulator (22) is arranged on a first main surface (23) of the carrier (21), - the at least one column line (5) is arranged between the carrier (21) and the electrical insulator (22) and - the recess (3) completely penetrates the electrical insulator (22).

5. Device (1) according to claim 4, further comprising a connection region (7) for connecting the electrical power supply (10) to the column line (5) and / or row line (6), wherein in the connection region (7) the source substrate (2) is free of the electrical insulator (22).

6. Device (1) according to one of the preceding claims, wherein a carrier (21) of the source substrate (2) in a connection area (7) for connecting the heating element (4) to the electrical power supply (10) has a smaller thickness than outside the connection area (7) .

7. Device (1) according to one of the preceding claims, wherein on one of the first main surface (23) of the carrier (21) facing away from the side of the electrical insulator (22), the at least one row line (6) is arranged and the electrical insulator (22) is flush with the row line (6) in a direction away from the carrier (21).

8. Device (1) according to one of the preceding claims, wherein the at least one row line (6) is arranged on a rear side (20) of the source substrate (2) and the row line (6) is electrically conductively connected to the heating element (4) via a via (25) through the source substrate (2).

9. Device (1) according to one of the preceding claims, wherein - the heating element (4) has a first layer (41) and a second layer (42), - the first layer (41) and the second layer (42) are electrically conductively connected to one another and - the first layer (41) at least partially covers at least the bottom region (30) of the recess (3) and the second layer (42) at least partially covers at least side surfaces (31) of the recess (3).

10. Device (1) according to one of the preceding claims, wherein at least the heating element (4) is at least partially covered by a protective layer (8).

11. Device (1) according to one of the preceding claims, wherein - the source substrate (2) is arranged on a roll (70), - the source substrate (2) has at least one functional unit (77), each having a plurality of recesses (3) and at least one connection area (7), - in the connection area (7) the heating elements (4) which are assigned to the recesses (3) of the functional unit (77) can be electrically contacted.

12. A method for using a device (1) according to any one of the preceding claims for applying a material (100) from a source substrate (2) to a target substrate (200), comprising the following steps: - introducing the material (100) into the recess, - applying an electric current to the heating element (4) so ​​that the heating element (4) is heated, - Partial evaporation of the material (100) in an area adjacent to the heating element (4), - Detaching the material (100) from the source substrate (2) and applying the material (100) to the target substrate (200).

13. The method according to claim 12, wherein - the material (100) is introduced into the recesses (3) by means of a doctor blade and - the electric current is applied to the heating element (4) by means of at least one contact needle (71).

14. The method according to claim 12 or 13, wherein after the material (100) has been detached from the source substrate (2), the recess (3) is cleaned.

15. The method according to any one of claims 12 to 14, wherein the method prints a structure for a micro-LED.

16. A method for producing a device (1) according to any one of the preceding claims, comprising the following steps: - Structuring a carrier (21) , - applying at least one column line (5) on a first main surface (23) of the carrier (21), - applying an electrical insulator (22) on a side of the column line (5) facing away from the first main side (23) of the carrier (21) and / or on the first main side (23) of the carrier (21), - Structuring the electrical insulator (22) so that at least one recess (3) is formed, - arranging at least one heating element (4) on the bottom region (30) and / or side surfaces (31) of the recess (3) so that the heating element (4) is electrically conductively connected to the column line (5), - Applying at least one row line (6) so that the heating element (4) is electrically conductively connected to the row line (6).

17. The method according to claim 16, wherein the row line (6) is arranged on a side of the electrical insulator (22) facing away from the first main side (23) of the carrier (21).

18. The method according to claim 16, wherein - the row line (6) is arranged on a second main surface (24) of the carrier (21) opposite the first main surface (23), - a through-contact (25) is formed through the carrier (21), which connects the row line (6) to the heating element (4) in an electrically conductive manner.

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