Method for producing an optoelectronic arrangement, optoelectronic arrangement and optoelectronic device

Abstract

The invention relates to a method for producing an optoelectronic arrangement, comprising the steps of - providing a carrier (1) with a top surface (1a) and a bottom surface (1b), - forming a plurality of contact pads (2) on the carrier (1) at the top surface (1a), each contact pad (2) being free of ferromagnetic materials, - forming a shielding (3) on the carrier (1), the shielding (3) at least partly surrounding each contact pad (2) in a lateral direction (L) and comprising a first ferromagnetic material, - providing a plurality of optoelectronic devices (4), each device comprising a second ferromagnetic material at a side facing the top surface (1a) of the carrier (1), - providing a magnet (5) at the bottom surface (1b) of the carrier (1), said magnet applying a magnetic force (F), - bringing the plurality of optoelectronic devices (4) close to the top surface (1a), and - attaching the plurality of optoelectronic devices (4) to the carrier (1) at the top surface (1a). The optoelectronic devices (4) can be micro-LEDs, for example.

Description

[0001] Description

[0002] METHOD FOR PRODUCING AN OPTOELECTRONIC ARRANGEMENT , OPTOELECTRONIC ARRANGEMENT AND OPTOELECTRONIC DEVICE

[0003] In the following, a method for producing an optoelectronic arrangement , an optoelectronic arrangement and an optoelectronic device are speci fied .

[0004] One obj ect to be achieved is to speci fy a method for producing an optoelectronic arrangement which is particularly gentle on the components of the arrangement . A further obj ect to be achieved is to speci fy a thus produced optoelectronic arrangement and optoelectronic devices suited for this method .

[0005] According to one aspect of the method, a carrier with a top surface and a bottom surface is provided . For example , the carrier is the back plane of the optoelectronic arrangement . For example , the carrier comprises conductor tracks and / or contact locations and / or switches and / or electronics for contacting and driving further components of the optoelectronic arrangement .

[0006] For example , it is possible that the carrier is a circuit board or a CMOS substrate . For example , the carrier has the shape of a plate or a disk . The carrier has , for example , a top surface and a bottom surface which are at least in parts parallel to a plane of main extension of the carrier and to each other .

[0007] According to at least one aspect of the method, a plurality of contact pads is given or formed on the carrier at the top surface , wherein each contact pad is free of ferromagnetic material .

[0008] For example , the contact pad is configured to contact further components of the optoelectronic arrangement . For this , the further components can be electrically conductively connected to the contact pad .

[0009] However, the contact pads are free of any ferromagnetic material and are formed by materials like aluminum, silver and / or gold, for example .

[0010] According to at least one aspect of the method, a shielding is formed on the carrier, the shielding at least partly surrounding each contact pad in a lateral direction and comprising a first ferromagnetic material . The lateral direction is a direction which is parallel to a plane of main extension of the carrier and / or parallel to the top surface and / or the bottom surface .

[0011] The shielding has the shape of a grid or a net , for example . The contact pads can be located in openings of the grid or the net . For example , exactly one contact pad or two or more contact pads are arranged in each opening of the grid or the net .

[0012] The shielding is applied to the top surface of the carrier, for example . However, it is also feasible that the shielding is applied to the bottom surface or that the shielding is applied to the bottom surface and the top surface of the carrier . In each case , the shielding at least partly surrounds each contact pad in the lateral direction . Each contact pad can also be completely surrounded by the shielding in a lateral direction .

[0013] The shielding also has an extension in a vertical direction, perpendicular to the lateral direction, which is denoted as the thickness of the shielding . The thickness of the shielding is at least 100 nm, for example .

[0014] The shielding comprises or consists of a first ferromagnetic material . For example , the shielding comprises or consists of at least one of the following materials : Fe , Co , Ni , Nd .

[0015] According to at least one aspect of the method, a plurality of optoelectronic devices is provided, wherein each device comprises a second ferromagnetic material at a side facing the top surface of the carrier .

[0016] For example , the optoelectronic devices comprise lightemitting devices like , for example , light-emitting diodes or laser diodes . Further, it is possible that the optoelectronic devices comprise light-detecting devices like , for example , photodiodes . Further, it is possible that only light-emitting devices , only light-detecting devices , or a mixture of lightemitting and light-detecting devices are provided as the optoelectronic device .

[0017] For example , each optoelectronic device comprises a semiconductor body with an active region where light is produced and / or detected . The second ferromagnetic material is applied at an underside of the semiconductor body . For example , the second ferromagnetic material comprises or consists of at least one of the following materials : Fe , Co , Ni , Nd . For example , it is also possible that the first ferromagnetic material and the second ferromagnetic material are the same or di f ferent materials .

[0018] According to at least one aspect of the method, a magnet is provided at the bottom surface of the carrier, wherein the magnet applies a magnetic force . This means that the magnet is provided at the side of the carrier which faces away from the top surface .

[0019] For example , the magnet can be a permanent magnet or an electromagnet , which has the advantage that the field strength of the electromagnetic field can be controlled .

[0020] According to at least one aspect of the method, the plurality of optoelectronic devices is brought close to the top surface of the carrier such that a magnetic force acts on the second ferromagnetic material . With this , it is possible to draw the optoelectronic devices in the direction of the top surface via the magnetic force . The shielding absorbs the magnetic field between neighboring contact pads . This means that the magnetic field passes only through areas where no shielding is deposited, and in this way the optoelectronic devices are drawn to the contact pads by the magnetic force .

[0021] According to at least one aspect of the method, the plurality of optoelectronic devices is attached to the carrier, in particular the contact pads at the top surface of the carrier . The magnetic force can be kept present during the attachment process , for example a soldering process . In this way, a force which draws the optoelectronic devices to the contact pads remains present during attachment without pressure being applied to the optoelectronic devices , for example from a side of the optoelectronic devices which faces away from the carrier . This allows , for example , for a very gentle way of attaching the optoelectronic devices to the carrier as no pressure is applied directly to the optoelectronic devices but the magnetic force acts at the underside of the devices , for example on a solder layer or a glue .

[0022] According to at least one aspect of the method for producing an optoelectronic arrangement , the method may comprise the following steps :

[0023] - providing a carrier with a top surface and a bottom surface ,

[0024] - forming a plurality of contact pads on the carrier at the top surface , each contact pad being free of ferromagnetic materials ,

[0025] - forming a shielding on the carrier, the shielding at least partly surrounding each contact pad in a lateral direction and comprising a first ferromagnetic material ,

[0026] - providing a plurality of optoelectronic devices , each device comprising a second ferromagnetic material at a side facing the top surface of the carrier,

[0027] - providing a magnet at the bottom surface of the carrier, the magnet applying a magnetic force ,

[0028] - bringing the plurality of optoelectronic devices close to the top surface , and

[0029] - attaching the plurality of optoelectronic devices to the carrier at the top surface .

[0030] It is possible that the steps of this method are performed in the given sequence . However, it is also possible that the sequence of steps is interchanged . For example , it is possible that the shielding is formed before the contact pads are formed . The herein described arrangement of optoelectronic devices and the herein described method inter alia rely on the following considerations and ideas .

[0031] In particular, small optoelectronic devices , such as microLEDs , are considered to be revolutioni zing displays with their minuscule si ze , enabling unmatched resolution, superior brightness , and a wider color spectrum . To achieve these advancements , several technological hurdles are yet to be overcome . For example , precise alignment during fastening, e . g . soldering and / or bonding, of light-emitting diodes is crucial for flawless display function, posing a signi ficant challenge due to the light-emitting diodes ' si ze and delicate nature .

[0032] In particular micro-LEDs , with si zes often below 100 microns in edge length, necessitate high- fidelity placement during soldering . Even minimal deviations can result in nonfunctional connections or parasitic electrical pathways . The slightest misalignment in the placement of micro-LEDS can lead to pixel defects and hinder display quality .

[0033] Small light-emitting diodes exhibit a high degree of sensitivity to the mechanical force exerted during the soldering process . The application of force beyond a certain threshold can result in structural damage to the lightemitting diode . Consequently, methodologies that employ low- pressure bonding techniques to mitigate potential harm to these light-emitting diodes are advantageous . To achieve precise placement of such small optoelectronic devices during fastening, several advanced techniques are employed : pick-and-place with optical detection systems utili zes high-precision robotic arms and cameras for image recognition-based placement , stencil printing with fiducials incorporates alignment markers on stencils that work with vision systems to precisely deposit solder paste for device placement , and / or micro-trans fer printing utili zes elastomeric stamps for precise trans fer onto pre-patterned substrates with pre-defined solder bumps . Finally, flip-chip bonding involves flipping and bonding devices onto substrates with solder bumps . However, even these advanced methods struggle to achieve the tri fecta of high throughput , precision, and cost-ef fectiveness simultaneously, especially as si zes of optoelectronic devices continue to shrink .

[0034] One idea of the here described method is , inter alia, that a precise placement of the optoelectronic devices is ensured during the attachment of the optoelectronic devices using a defined pattern of magnetic force . This pattern is made possible by the shielding which surrounds the contact pads to which the optoelectronic devices are attached in the lateral direction .

[0035] The use of the magnet and the ferromagnetic materials in the optoelectronic devices and the shielding allows for the guided attraction of each optoelectronic device to the nonpatterned side of the back plane , where the shielding is not present . The application of the magnetic field during the attachment process generates an attractive force . This ef fectively shi fts the pressure from the optoelectronic device to the underlying ferromagnetic material , thereby mitigating or avoiding potential damage to the optoelectronic devices .

[0036] According to at least one aspect of the method, the magnetic force is applied to the plurality of optoelectronic devices until the plurality of optoelectronic devices is attached to the carrier . In other words , the force is kept in place until the optoelectronic devices are firmly attached to the carrier and, for example , in electrical contact with the contact pads .

[0037] According to at least one aspect of the method, each contact pad is completely surrounded by the shielding in the lateral direction . In this case the shielding is , for example , given in the shape of a net or a grid with openings . At least one contact pad is placed in each opening . Further, in particular exactly one optoelectronic device is placed into each opening and attached to the at least one contact pad in the opening .

[0038] According to at least one aspect of the method, each optoelectronic device is attached to a post and is removed from the post by the magnetic force provided by the magnet as it approaches the top surface . For example , the post is formed by a rigid or flexible material and is attached to the semiconductor body of each optoelectronic device . Thereby it is possible that the optoelectronic devices are removed from the posts due to the magnetic force . As an alternative , it is possible to remove the posts after the optoelectronic devices have been attached to the carrier .

[0039] According to at least one aspect of the method, the second ferromagnetic material is part of a stack of solder material . This means that the second ferromagnetic material is included into a stack of solder material , which is applied at the underside of each optoelectronic device . For example , the second ferromagnetic material can be included as a layer, for example as a middle layer which is surrounded on its underside and its top side by solder material , into the stack of solder material . Thereby, the strength of the magnetic force which acts on each optoelectronic device can be adj usted by adj usting the thickness of this layer .

[0040] Further, it is alternatively or additionally possible that the stack of solder material is doped with the second ferromagnetic material . The strength of the magnetic force can then, for example , be set by adj usting the concentration of the dopant .

[0041] According to at least one aspect of the method, the Curie temperature of the second ferromagnetic material is greater than the melting temperature of the solder material . This makes it possible for the magnetic force to stay present during the whole solder process , keeping the optoelectronic devices aligned with the contact pads . For example , it is possible that the Curie temperature of the second ferromagnetic material and the solder material di f fer by at most 25% from each other .

[0042] Further, an optoelectronic arrangement is speci fied . The here described optoelectronic arrangement can be produced by means of the here described method . Consequently, all features disclosed for the method for producing an optoelectronic arrangement are also disclosed for the optoelectronic arrangement . According to at least one aspect of the optoelectronic arrangement , the arrangement comprises : a carrier with a top surface and a bottom surface , a plurality of contact pads at the top surface , each contact pad being free of ferromagnetic materials , a shielding at the top surface , the shielding at least partly surrounding each contact pad in a lateral direction and comprising a first ferromagnetic material , a plurality of optoelectronic devices , each device comprising a second ferromagnetic material at a side facing the top surface of the carrier, wherein

[0043] - each optoelectronic device is attached to at least one of the contact pads at the top surface .

[0044] According to at least one aspect of the optoelectronic arrangement , the optoelectronic devices are light-emitting diodes ( LEDs ) , in particular micro-LEDs .

[0045] A micro-LED can be seen as any light-emitting diode ( LED) - generally not a laser - with a particularly small si ze .

[0046] In particular, a growth substrate can be removed from micro- LEDs , so that typical heights of such micro-LEDs are in the range of at least 1 . 5 pm to at most 10 pm, for example .

[0047] In principle , a micro-LED does not necessarily have to have a rectangular radiation emission surface . Generally, for example , an LED could have a radiation emission surface in which, in plan view of the layers of the layer stack, any lateral extent of the radiation emission surface is less than or equal to 100 pm or less than or equal to 70 pm or less than or equal to 10 pm .

[0048] For example , in the case of rectangular micro-LEDs , an edge length - especially in plan view of the layers of the layer stack smaller than or equal to 70 qm or smaller than or equal to 50 qm is advantageous .

[0049] Mostly, such micro-LEDs are provided on wafers with detachable holding structures .

[0050] Micro-LEDs can be used in displays . The micro-LEDs form pixels or subpixels and emit light of a defined color . Small pixel si zes and a high density with close distances make micro-LEDs suitable , among others , for small monolithic displays for AR applications , especially data glasses . In addition, other applications are being developed, in particular regarding their use in data communication or pixelated lighting applications .

[0051] Di f ferent ways of spelling micro-LED, e . g . qLED, q-LED, uLED, u-LED or micro light emitting diode can be found in the relevant literature .

[0052] According to at least one aspect of the optoelectronic arrangement , the arrangement forms a display device . For example , the optoelectronic devices form pixels or subpixels of a display . In particular in cases where the optoelectronic devices are micro-LEDs , a display with a small pitch and a high density of pixels can be achieved by the here described optoelectronic arrangement and the here described method for producing an optoelectronic arrangement .

[0053] Further, an optoelectronic device is speci fied . The optoelectronic device can be part of a here described optoelectronic arrangement . Consequently, all features disclosed for the here described optoelectronic arrangement and the here described method for producing an optoelectronic arrangement are also disclosed for the optoelectronic device and vice versa .

[0054] According to at least one aspect , the optoelectronic device comprises a semiconductor body comprising an active region . The semiconductor body is based on a I I I-V compound semiconductor material , for example .

[0055] A I I I-V compound semiconductor material has at least one element from the third main group, such as B, Al , Ga, In, and one element from the fi fth main group, such as N, P, As . In particular, the term ' I I I-V compound semiconductor material ' comprises the group of binary, ternary or quaternary compounds which contain at least one element from the third main group and at least one element from the fi fth main group, for example nitride and phosphide compound semiconductors . Such a binary, ternary or quaternary compound may also have one or more dopants and additional components , for example .

[0056] For example , the semiconductor body comprises at least one active region which is arranged to detect and / or produce electromagnetic radiation, in particular light . Thereby it is possible that the optoelectronic device is a light-emitting diode , in particular a micro-LED .

[0057] During operation, the light-emitting diode can produce colored light , for example . Thereby it is possible that di f ferent optoelectronic devices which produce light of di f ferent colors are included in a here described optoelectronic arrangement . For example , the optoelectronic arrangement comprises optoelectronic devices which produce red light during operation, optoelectronic devices which produce green light during operation and optoelectronic devices which produce blue light during operation .

[0058] According to at least one aspect of the optoelectronic device , the optoelectronic device comprises a stack of solder material at an underside of the semiconductor body, wherein the magnetic permeability number of the stack of solder material is adj usted .

[0059] The magnetic permeability number, also known as " relative permeability" , is in particular increased for the here described optoelectronic devices in comparison with common optoelectronic devices . With this , it is possible that the magnetic force which acts on the optoelectronic devices during attachment can be increased .

[0060] According to at least one aspect of the optoelectronic device , the optoelectronic device comprises : a semiconductor body comprising an active region, a stack of solder material at an underside of the semiconductor body, wherein the magnetic permeability number of the stack of solder material is adj usted .

[0061] According to at least one aspect of the optoelectronic device , the stack of solder material comprises a ferromagnetic material . This means that the magnetic permeability number is adj usted by introducing a ferromagnetic material into the stack of solder material . This can be done , for example , by introducing at least one layer which is formed with the ferromagnetic material into the stack . Thereby, by adj usting the thickness of the layer, the magnetic permeability number of the stack of solder material is adj usted . For example , by increasing the thickness of the layer, the magnetic permeability number of the stack of solder material is increased .

[0062] Alternatively or additionally, it is possible to dope the stack of solder material with a dopant of the ferromagnetic material . By adj usting the concentration of the dopant in the stack, the magnetic permeability number of the stack of solder material can also be adj usted .

[0063] In the following, the here described method for producing an optoelectronic arrangement , the here described optoelectronic arrangement and the here described optoelectronic device are described in more detail with reference to exemplary embodiments and figures .

[0064] The schematical drawings of Figures 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 illustrate method steps of a here described method for an exemplary embodiment of the here described method for producing an optoelectronic arrangement .

[0065] The schematical drawings of Figures 9 and 10 are used to illustrate an embodiment of a here described optoelectronic arrangement .

[0066] The schematical drawing of Figure 11 is used to illustrate an exemplary embodiment of a here described optoelectronic device .

[0067] In the exemplary embodiments and figures , similar or similarly acting constituent parts are provided with the same reference symbols . The elements illustrated in the figures and their si ze relationships among one another should not be regarded as true to scale . Rather, individual elements may be represented with an exaggerated si ze for the sake of better representability and / or for the sake of better understanding .

[0068] The schematic cross-sectional view of Figure 1 shows a first method step for an exemplary embodiment for a here described method for producing an optoelectronic arrangement . In the first method step, a carrier 1 is provided which has a top surface la and a bottom surface lb . The carrier 1 is a back plane or a CMOS substrate , for example . The carrier 1 is coated with a photoresist 8 on its top surface la, and the photoresist 8 is patterned such that there are openings in which the top surface la is freely accessible .

[0069] In a subsequent method step, Figure 2 , a contact metal layer 9 is deposited at the top surface la onto the carrier 1 .

[0070] Subsequently, Figures 3 and 4 , the photoresist 8 is li fted of f , resulting in contact pads 2 , which are arranged on the carrier 1 at the top surface la . Thereby each contact pad 2 is free of a ferromagnetic material , in particular free of any ferromagnetic material . Figure 4 shows a top view onto the top surface la of the carrier 1 for this method step .

[0071] In the next method step, Figure 5 , the contact pads 2 are coated with a photoresist 8 and the photoresist is patterned in order to produce openings in which the top surface la of the carrier 1 is freely accessible . This is shown in Figure 5 .

[0072] In a subsequent method step, Figure 6 , a metallic shielding material 10 is deposited onto the top surface la of the carrier 1 . Subsequently, Figures 7 and 8 , the photoresist 8 is li fted of f and the shielding 3 is formed on the carrier 1 , at least partly surrounding each contact pad 2 in a lateral direction L and comprising a first ferromagnetic material . Figure 7 shows a sectional schematic view and Figure 8 shows a top schematic view of this arrangement .

[0073] Alternatively, it is possible that the shielding is produced before the contact pads and / or that the shielding is produced on the bottom surface lb of the carrier 1 .

[0074] As can be seen from Figure 7 , for example , the thickness of the shielding 3 can be lower than the thickness of the contact pads 2 . However, it is also possible that the shielding 3 is thicker and is flush with the contact pads 2 in a vertical direction or even thicker than the contact pads 2 .

[0075] In a next method step, Figure 9 , optoelectronic devices 4 , which comprise a semiconductor body 40 and a stack 7 of solder material , for example , are brought , as an array and held by posts 6 , in the vicinity of the top surface la of the carrier 1 . Each of the optoelectronic devices 4 comprises a second ferromagnetic material at a side facing the top surface la of the carrier 1 , for example in the stack 7 .

[0076] Further, a magnet 5 , e . g . an electromagnet , is placed at the bottom surface lb of the carrier 1 . The magnet applies a magnetic force F in the direction of the top surface la, which enables the placement of the optoelectronic devices in the speci fic areas where the magnetic attraction is ef fective . These are the non-patterned areas on the contact pads 2 , which are not covered by the shielding 3 .

[0077] After detachment of the post 6 from the optoelectronic devices 4 , the arrangement as shown in the top view of Figure 10 results . During the method, the magnetic force F is applied to the plurality of optoelectronic devices 4 until the plurality of optoelectronic devices 4 is attached to the carrier 1 . For example , the force is applied during a solder process . In this case , it is advantageous that the Curie temperature of the second ferromagnetic material is greater than the melting temperature of the solder material of the stack 7 .

[0078] The optoelectronic arrangement according to the embodiment of Figure 10 comprises the carrier 1 with the top surface la and the bottom surface lb, a plurality of contact pads 2 at the top surface la, wherein each contact pad 2 is free of any ferromagnetic material , a shielding 3 at the top surface la, the shielding 3 at least partly surrounding each contact pad 2 in the lateral direction L and comprising a first ferromagnetic material , a plurality of optoelectronic devices 4 , each device comprising a second ferromagnetic material at a side facing the top surface la of the carrier 1 , wherein each optoelectronic device is attached to at least one of the contact pads 2 of the top surface la .

[0079] According to the embodiment of Figure 10 , there is exactly one contact pad 2 for each optoelectronic device , from which the device is contacted on its p-side or its n-side , for example . A further contact can, for example , be made by a contact layer or a bonding wire on the opposite side of each optoelectronic device (not shown) . Further, it is possible that for each optoelectronic device at least two contact pads are present , and the optoelectronic device is of a flip-chip design and therefore contacted from one side only . Here , it is possible that the two contact pads are arranged together in the same opening of the shielding 3 or each contact pad is arranged in its own opening of the shielding 3 .

[0080] For example , the optoelectronic arrangement of Figure 10 is a display device and the optoelectronic devices 4 are lightemitting devices like for example light-emitting diodes such as micro-LEDs .

[0081] Figure 11 shows a schematic drawing which illustrates an embodiment of a here described optoelectronic device . The optoelectronic device is , for example , a light-emitting or a light-detecting optoelectronic device comprising a semiconductor body 40 with an active region 41 which is configured to detect and / or emit light .

[0082] At the underside 40b of the semiconductor body, a stack 7 of solder material comprising a first layer 71 , a second layer 72 and a third layer 73 is arranged . For example , the second layer 72 is formed with the second ferromagnetic material and comprises at least one of the following materials : Fe , Ni , Co , Nd .

[0083] Additionally or alternatively, it is possible that the stack 7 is doped with a dopant 74 of the second ferromagnetic material . By the thickness of the layer comprising the ferromagnetic material and / or the dopant , the magnetic permeability number of the stack 7 is adj usted such that the magnetic force acting on the optoelectronic device during production of the optoelectronic arrangement can be adj usted .

[0084] The features and exemplary embodiments described in connection with the figures can be combined with one another in accordance with further embodiments , even i f not all combinations are explicitly described . Furthermore , the embodiments described in connection with the figures may alternatively or additionally have further features as described in aspects and claims .

[0085] This patent application claims the priority of German patent application 102024118032 . 3 , the disclosure content of which is hereby incorporated by reference .

[0086] The invention is not restricted to the exemplary embodiments by the description on the basis of said exemplary embodiments . Rather, the invention encompasses any new feature and also any combination of features , which in particular comprises any combination of features in the patent claims and any combination of features in the exemplary embodiments , even i f this feature or this combination itsel f is not explicitly speci fied in the patent claims or exemplary embodiments .

[0087] References

[0088] 1 carrier la top surface lb bottom surface

[0089] 2 contact pad

[0090] 3 shielding

[0091] 4 optoelectronic device

[0092] 40 semiconductor body

[0093] 40b underside

[0094] 41 active region

[0095] 5 magnet

[0096] 6 post

[0097] 7 stack

[0098] 71 first layer

[0099] 72 second layer

[0100] 73 third layer

[0101] 74 dopant

[0102] 8 photoresist

[0103] 9 contact metal layer

[0104] 10 shielding material

[0105] L lateral direction

[0106] F force

Claims

Claims1. A method for producing an optoelectronic arrangement with- providing a carrier (1) with a top surface (la) and a bottom surface (lb) ,- forming a plurality of contact pads (2) on the carrier (1) at the top surface (la) , each contact pad (2) being free of ferromagnetic materials,- forming a shielding (3) on the carrier (1) , the shielding (3) at least partly surrounding each contact pad (2) in a lateral direction (L) and comprising a first ferromagnetic material ,- providing a plurality of optoelectronic devices (4) , each optoelectronic device (4) comprising a second ferromagnetic material at a side facing the top surface (la) of the carrier(1) ,- providing a magnet (5) at the bottom surface (lb) of the carrier (1) , said magnet (5) applying a magnetic force (F) ,- bringing the plurality of optoelectronic devices (4) close to the top surface (la) , and- attaching the plurality of optoelectronic devices (4) to the carrier (1) at the top surface (la) .

2. The method according to the previous claim, wherein the magnetic force (F) is applied to the plurality of optoelectronic devices (4) until the plurality of optoelectronic devices (4) is attached to the carrier (1) .

3. The method according to at least one of the previous claims, wherein each contact pad (2) is completely surrounded by the shielding (3) in the lateral direction (L) .

4. The method according to at least one of the previous claims, wherein each optoelectronic device (4) is attached to a post (6) and is removed from the post (6) by the magnetic force (F) provided by the magnet (5) as it approaches the top surface ( la) .

5. The method according to at least one of the previous claims, wherein the second ferromagnetic material is part of a stack (7) of solder material.

6. The method according to the previous claim, wherein theCurie temperature of the second ferromagnetic material is greater than the melting temperature of the solder material.

7. An optoelectronic arrangement comprising a carrier (1) with a top surface (la) and a bottom surface ( lb) , a plurality of contact pads (2) at the top surface (la) , each contact pad (2) being free of ferromagnetic materials, a shielding (3) at the top surface (la) , the shielding (3) at least partly surrounding each contact pad (2) in a lateral direction (L) and comprising a first ferromagnetic material , a plurality of optoelectronic devices (4) , each optoelectronic device (4) comprising a second ferromagnetic material at a side facing the top surface (la) of the carrier ( 1 ) , wherein- each optoelectronic device (4) is attached to at least one of the contact pads (2) at the top surface (la) .

8. The optoelectronic arrangement according to the previous claim, wherein each contact pad (2) is completely surrounded by the shielding (3) in the lateral direction (L) .

9. The optoelectronic arrangement according to at least one of the two previous claims, wherein the second ferromagnetic material is part of a stack (7) of solder material.

10. The optoelectronic arrangement according to at least one of the three previous claims, wherein the optoelectronic devices (4) are LEDs, in particular micro-LEDs.

11. The optoelectronic arrangement according to at least one of the four previous claims, wherein the arrangement forms a display device.

12. An optoelectronic device (4) comprising a semiconductor body (40) comprising an active region (41) , a stack (7) of solder material at an underside (40b) of the semiconductor body (40) , wherein the magnetic permeability number of the stack (7) of solder material is adjusted, wherein the stack (7) is doped with a dopant (74) of a ferromagnetic material.

13. The optoelectronic device (4) according to the previous claims, wherein the stack (7) comprises at least one layer (71, 72, 73) which is formed with the ferromagnetic material.

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