Multi-chip carrier structure

Abstract

A carrier structure (10) for picking up a flat microchip (16) using a flat carrier substrate (22) and at least two pick-up elements (20), the pick-up elements (20) being connected to the carrier substrate (22) and configured to releasably hold a flat microchip (16) between the at least two pick-up elements (20), such that the microchip (16) can be moved in a direction perpendicular to the plane of the carrier structure with a defined minimum force.

Description

[Technical field]

[0001] This patent application claims the priority of German Patent Application Publication No. 102019112490.5, filed May 13, 2019, and of International Application No. PCT / EP2020 / 052191, filed January 29, 2020, the disclosures of which are incorporated herein by reference.

[0002] The present invention relates to optoelectronic components, more generally semiconductor components for optical displays. In particular, the present invention relates to a carrier structure for LED chips for use in a mass-production transfer process for the manufacture of optoelectronic displays.

[0003] 2. Background of the Invention While organic LED technology has received particular attention in recent years, inorganic light-emitting diodes are once again gaining attention as the basis for new applications, including video walls, interior lighting, automotive interiors, headlights or gadget lighting, general lighting fixtures and lighting for special applications in the industrial sector, in addition to traditional display applications.

[0004] Essentially, the technology for generating light follows known processes known from classical optoelectronic structural elements, also called LEDs. In particular, the possibility of realizing LEDs with high brightness and high contrast at low power consumption opens up new fields of application. However, one major difference is that the sizes of these LED chips are very diverse and tailored to the respective application. The size ranges from 1 mm 2 to about 100 μm 2 is in the range.

[0005] When manufacturing such LEDs on a wafer, in addition to various technical challenges regarding the precision, efficiency and effectiveness of the LED manufacturing process, it is important to transfer the LEDs defect-free onto the backplane or CB etc. and then make electrical contact. Although this size of the LEDs may make it possible to repair or replace defective light-emitting diodes later, a sufficiently error-free transfer and precise positioning of the LEDs with the fixtures can further reduce the risk of failure and therefore the costs.

[0006] Methods are known, such as transfer printing processes, in which several LEDs are picked up simultaneously from a wafer by a flat stamp and transferred to the support surface of the subsequent display, where they are precisely assembled to form the entire large-area structure. For this, for example, elastomeric stamps can be used, to which, due to the appropriate surface texture and material properties, the individual LEDs are attached without being mechanically or electrically damaged. For this stamps, so-called PDMS elastomers based on silicone are used, for example. Often these elastomeric stamps have a so-called cushion structure, which can allow a good targeted adhesion of the chips to be placed. Further transfer printing processes are known in the prior art. Besides the described processes based on elastomers, magnetic, electrostatic or mechanical processes based, inter alia, on rolling motion are known.

[0007] After their manufacture on a wafer, the finished LEDs must be able to be picked up by a suitable process or transferred to another location. For this, the LEDs are usually detached from the substrate, for example by an etching process. There are also laser-induced processes that detach the LEDs from the carrier. However, a complete detachment may also result in tilting, misalignment or twisting, so it may be desirable to enable pick-up for so-called mass transfer to a carrier without excessive holding forces or breakage.

[0008] Here, one aspect concerns how to avoid breaking edges and improve lift-up. For this purpose, a solution is proposed in which a crystalline dielectric support structure is used to maintain a mechanical connection between the LED and the surrounding or underlying substrate. However, this mechanical connection is designed such that, on the one hand, it mechanically holds the LED chip in place reliably, but on the other hand it breaks when subjected to the smallest possible bending or pulling forces, so that the chip can be released and removed.

[0009] In particular, a carrier structure is proposed for picking up areal chips or LEDs. Carrier structure here means an arrangement which allows picking up a large number of such LEDs, for example with an edge length in the range of 1 mm to about 100 μm or 800 μm to 150 mm. The aim here is in particular to provide a mechanically stable fixation, for example to a grid or matrix, while making the best possible use of the available space. Furthermore, the carrier structure is suitable for providing a plurality of chips for transfer by means of a transfer tool.

[0010] Furthermore, the carrier structure has at least two pick-up elements connected to the carrier substrate. Pick-up elements here are to be understood as mechanisms or functional elements suitable for spatially fixing or holding the LED in a defined spatial position in mechanical contact, if necessary by interacting with further pick-up elements. The pick-up elements may have a diameter of, for example, 10 μm or less, for example in the range of 2 μm or 1 μm. According to one embodiment, the chip is attached to the two pick-up elements.

[0011] In some embodiments, the carrier structure includes a flat carrier substrate. Such a carrier substrate can be, for example, a wafer, a sheet (folie), a frame, etc., used in the field of semiconductor manufacturing. In this context, for example, a wafer, in addition to its function as a base plate or base material for the semiconductor manufacturing process, can provide a support or supporting function to prepare for the subsequent mass production transfer. In addition, flexible materials, such as, for example, sheets, are also suitable as carrier substrates.

[0012] According to one embodiment, the pick-up elements are shaped like columns, pillars or poles starting from the carrier substrate. In one configuration, the chip is partially but not completely placed at its corners or edges on at least two pick-up elements. The pick-up elements are connected to the carrier substrate and are configured to detachably hold the chip between the at least two pick-up elements such that the LED can be moved with a defined minimum force in a direction perpendicular to the carrier structure plane.

[0013] In other words, on the one hand, the LED must be held sufficiently securely by the pick-up element, and on the other hand, the possibility must be deliberately created to remove the LED with minimal force and, for example, to feed it to a transfer tool. For this purpose, it may be proposed that the contact area of ​​each mounting element is less than 1 / 20, in particular less than 1 / 40, in particular within the range of 1 / 200 to 1 / 50, of the chip area of ​​the LED. In an alternative configuration, the edge length of the LED is at least 10 times, in particular 20 times, the edge length of the pick-up element. In one embodiment, the edge length is in particular in the range of 40 times to 80 times the edge length of the pick-up element.

[0014] By "detachable" is to be understood a non-destructive, detachable connection between the chip and the pick-up element without any permanent material bond, for example fusion or gluing. The attachment may be based on a physical connection, such as an adhesive connection by van der Waals forces or electronic bridges. The same can be achieved by using different materials between the LED and the pick-up element and by appropriately selecting the connection between the LED and the pick-up element. This is intended in particular to avoid processes such as breakage, which entails the destruction of the material structure and the corresponding fragments, particles or chips. Here, alternative adhesion mechanisms are used, such as mechanical friction or delamination. In particular, known limited or restricted adhesion properties of materials or material combinations are exploited. According to an embodiment, the LED is placed between two or more pick-up elements.

[0015] For example, at the contact surfaces, adhesive or other cohesive forces arise that can mechanically fix the LED in space. Now, when a defined minimum force is applied to the LED, for example by an attached transfer tool, a peel force is effective at the contact surfaces between the LED and the pick-up element. This defined minimum force can be influenced by an appropriate selection of materials or material combinations at these contact surfaces.

[0016] The contact or overlap surface is, for example, 0.05 μm 2 ~10μm 2 In the range of 1 μm 2 ~8μm 2Here, on the one hand, it is desirable to hold the LEDs securely on the carrier structure. On the other hand, for an effective and rapid mass transfer of the LEDs, it is important that the LEDs can be lifted up and detached with as little force as possible. For this purpose, it may be proposed that the ratio of the contact area of ​​each element with the chip to the total area of ​​the chip is less than 1 / 20, in particular less than 1 / 40, in particular in the range of 1 / 80 to 1 / 50, of the chip area. In an alternative configuration, the edge length of the LED is at least 10 times, in particular 20 times, the edge length of the pick-up element. Even if the area of ​​use of the pick-up element can be larger, the LED is only placed on a part of it. The contact area of ​​the chip is therefore at least 1 / 20, in particular at least 1 / 40, of the total chip area.

[0017] In this case, a suitable compromise has to be found, for example by suitable selection of the material or material combination as well as the dimensions and arrangement of the contact surface. Likewise, the size and shape of this contact surface can be configured to influence the defined minimum force: the larger the contact surface, the higher the minimum force required to detach the LED from the carrier structure. Besides holding principles based on friction or lamination, magnetic or electrical holding forces are also conceivable.

[0018] In another example, the carrier structure may have only one pick-up element for holding the LED. Due to the light weight of the semiconductor structure, it may be considered that a contact surface with a suitable shape and sufficient dimensions between the single pick-up element and the LED may provide a sufficient holding force in combination with a minimum force of suitable height to detach the LED.

[0019] In one configuration, a substrate for producing the LEDs may be used as the carrier structure. In such a case, a sacrificial layer may be provided. In this connection, the LEDs are connected to the growth substrate during the manufacturing process. To expose the finished LEDs, the intervening sacrificial layer is removed, for example by a gas or plasma-based etching process, thus creating a space between the LEDs and the wafer. The thickness of the sacrificial layer is, for example, between 100 nm (nanometers) and 500 nm. It is intended that, by removing the sacrificial layer, the pick-up element takes over the holding function of the LEDs on the carrier structure. In one configuration, the pick-up element may have the shape of an anchor.

[0020] Typically, the LED is pulled away from the carrier substrate with a force vector that is at least partially perpendicular to the carrier substrate plane (understood in the xy direction). The pick-up element therefore remains on the carrier substrate and is not particularly damaged. This ensures that no residues of the pick-up element remain on the LED, which may be problematic for further processing. In one embodiment, the force vector is substantially perpendicular to the surface. Furthermore, the holding force that holds the LED to the stamp is greater than the holding force that holds the LED to the pick-up element, immediately before and at least immediately after the lift-up.

[0021] According to one embodiment, at least one pick-up element is configured to simultaneously hold and / or support at least one other arranged LED adjacent to it. For example, the pick-up element is configured to support two, three or four LEDs arranged next to each other. Adjacent here means that the sides of the LEDs are substantially parallel to each other. Providing a distance between two adjacent LEDs can prevent them from affecting each other when lifted up. Such a distance is effective to prevent two adjacent LEDs from colliding when lifted up, especially when the force vector is not completely perpendicular. Thus, the distance between two adjacent LEDs can also depend on the component of the force vector parallel to the LED when lifted up. In some considerations, the distance between the two LEDs is 5% of the edge length or in the range of 1% to 10% of the edge length of the LED.

[0022] A consideration of this feature can be summarized as follows: LED support structures often take up space, which is ideally minimized in order to achieve a high yield on the wafer. Due to the manufacturing process, the LEDs are also arranged in parallel, regular structures on the wafer.

[0023] As mentioned above, space is generated due to the process. Therefore, the inventors propose to position a pickup element between two adjacent arranged LEDs, so that this one pickup element supports or picks up the adjacent LEDs. Here, it can be advantageously realized that arithmetically less than one overall support structure can be realized per part. This can reduce the total number of pickup elements, resulting in space saving and therefore cost reduction. Moreover, the overall chip yield is substantially constant, since it is not necessary to sacrifice the number of LEDs by adding space for the support structure on the wafer.

[0024] For example, the pick-up elements may have contact surfaces arranged opposite each other, each being in mechanical contact with the LED adjacent in this direction. In this case, the pick-up elements may be distributed and arranged on the surface of the carrier substrate in such a way that a minimum number of pick-up elements is used to hold the LED reliably. This may be advantageous, for example, to allow an effective and rapid pick-up of the LED, with an effective use of a transfer tool. According to one embodiment, the pick-up elements are arranged on the carrier substrate in such a way that one LED is held by exactly three pick-up elements. In this case, the selection of three pick-up elements may be an advantageous compromise, in that here good spatial stability can be combined with an advantageous distribution of the holding forces. Here, lateral deviations and tilts, especially on the carrier substrate, can be effectively prevented. In this connection, the pick-up elements may engage the chip in different lateral areas in the X-direction and the Y-direction, for example in the center, in an off-center position or at an edge or corner. Several pick-up elements may be arranged on one and the same surface of the LED.

[0025] According to one embodiment, a delamination layer is provided on the LED or on the pickup element to move the LED from the carrier structure. In this specification, the term delamination layer is intended to describe the delamination process that occurs when two surfaces come into contact, or more generally when two layers connect. This can apply to materials that are homogeneous, but also to materials that connect or surfaces that are different materials.

[0026] The purpose of intentionally creating a so-called delamination layer is to prevent damage processes or material destruction processes or structure change processes and instead to non-destructively peel off layers or surfaces from each other. Here, certain material combinations can be used, for example SiO2 and Al2O3, but also non-oxidizing metals such as silver, gold or similar materials in combination with a dielectric such as SiO2. Thus, in one embodiment, a delamination layer is formed between the LED and the pick-up element, since the surface of the pick-up element is surrounded by a delamination layer. The thickness of the delamination layer is only a few nm, for example in the range of 5 nm to 50 nm. In one embodiment, the delamination layer can be formed as an etching stop layer and can also optionally extend to cover further parts of the carrier structure.

[0027] According to one embodiment, the pick-up elements are arranged in mesa trenches of a semiconductor wafer. As mentioned above, in principle, optimal utilization of the space on the wafer is desirable for a high yield. Support structures for LEDs often require additional space. In the manufacturing process, various process steps create three-dimensional structures, where, for example, the LEDs are finally formed as protrusions or mesas. So-called mesa trenches are formed between these individual LEDs.

[0028] The term mesa trench refers to a relatively steep flank-like shape on the side of the LED, with the trench, i.e. the area without epitaxy, being a deep structure in between. For example, the mesa trench may have a flank steepness in the range of 30°-75°, in particular 45°. This is then intended to position the pick-up element exactly in this anyway available area, without taking up additional space on the wafer. In this way, the available space on the wafer can be better utilized.

[0029] According to one embodiment, the carrier structure and the pick-up element are integrally formed. This means, for example, that the pick-up element is part of a carrier substrate. Here, the carrier substrate may itself be a wafer, but also a structure such as a PCB board, a sheet, a frame, etc. In the latter case, this means that the pick-up element itself is made of a material and / or structure different from the carrier substrate. This can be achieved, for example, in the manufacturing process by specifically maintaining the wafer structures present from the beginning through the various process steps in a locally limited manner and not removing them, for example by an etching process. These structures then serve as pick-up elements and support structures for the finished LED.

[0030] In one embodiment, the pick-up element is configured to hold the LED laterally and from below the LED. In one embodiment, it may be useful to create partial contact surfaces or contact surfaces that provide a mechanical stop in the Z direction, i.e. in the direction of the carrier substrate, for holding the LED on the underlying carrier substrate, on the one hand. At the same time, a spatial fixation in the lateral direction, i.e. in the X and Y directions, can be provided by providing additional lateral holds. In this way, on the one hand, a stable spatial fixation in the direction of the carrier substrate and in the lateral direction is possible, and on the other hand, an easy lift-up of the LED by a transfer process or transfer tool is possible in the Z direction away from the carrier substrate.

[0031] In one embodiment, the pick-up element has an LED-retaining surface that extends obliquely relative to the carrier substrate plane, such that the retention force on the LED decreases as the LED moves away from the pick-up element. In other words, the further the LED moves away from the carrier substrate, the further away the retention surface is from the LED. This can also be understood as a progressive decrease in retention force, for example, as the LED is lifted up from the carrier structure by the transfer tool. This advantageously reduces the force required to detach the LED, with the main aim of reducing, in particular, the execution time of the process steps and improving the quality of the transfer process.

[0032] The present disclosure is further explained by the following detailed description. The detailed description and specific examples disclose various aspects and embodiments to explain the proposed principles. Those skilled in the art will understand that they can make changes and modifications within the scope of the present disclosure under the guidance of the detailed description.

[0033] Therefore, it is self-evident that the disclosure disclosed herein is not limited to the specific components of the described device or steps of the described method, since such devices and such methods may vary. It is also self-evident that the terms used herein are for describing a particular configuration and are not intended to be limiting. It should be noted that, as used in this specification and the appended claims, definite and indefinite articles are intended to mean that there is one or more elements, unless the context clearly dictates otherwise. For example, the expression "eine Einheit" or "die Einheit" may include multiple devices, etc. Furthermore, words such as "umfassend", "umfassend", "enthaltend", etc. do not exclude other elements or steps. [Brief description of the drawings]

[0034] [Figure 1A] FIG. 13 is a diagram showing a schematic flow of mass production transfer printing for transferring multiple LEDs onto a wafer. [Figure 1B] FIG. 13 is a diagram showing a schematic flow of mass production transfer printing for transferring multiple LEDs onto a wafer. [Figure 1C] FIG. 13 is a diagram showing a schematic flow of mass production transfer printing for transferring multiple LEDs onto a wafer. [Figure 1D] FIG. 13 is a diagram showing a schematic flow of mass production transfer printing for transferring multiple LEDs onto a wafer. [Diagram 2] 1 shows a carrier structure with three pick-up elements according to the proposed principle in plan view. [Figure 3A] FIG. 1 shows a vertical cross section of a carrier structure for picking up flat LEDs suitable for the proposed transfer. [Figure 3B] FIG. 1 shows a vertical cross section of a carrier structure for picking up flat LEDs suitable for the proposed transfer. [Figure 3C] FIG. 1 shows a vertical cross section of a carrier structure for picking up flat LEDs suitable for the proposed transfer. [Figure 3D] FIG. 1 shows a vertical cross section of a carrier structure for picking up flat LEDs suitable for the proposed transfer. [Figure 3E] FIG. 1 shows a vertical cross section of a carrier structure for picking up flat LEDs suitable for the proposed transfer. [Figure 4] 13A-13D show layouts of a carrier structure according to some embodiments of a proposed concept with a flat LED and multiple pick-up elements in different arrangements. [Diagram 5] FIG. 13 shows a further layout of a carrier structure prepared and suitable for the proposed transfer process.

[0035] Below we present some concepts for measures to improve the transfer in the form of an improved mass-production transfer printing process. This process is used because the LEDs of a wafer are transferred to the support surface of the display, where the individual LEDs are not only fixed and mounted but also electrically connected. On the one hand, the dimensions of the individual LEDs are in the range of only a few [μm]n, and on the other hand, a large number of these LEDs must be transferred locally at the same time. In this case, several thousand such structures must frequently be transferred from a large number of wafers to a common support surface.

[0036] In this regard, the example shown in FIG. 1 first provides a wafer 12 on which epitaxial layers are created by various semiconductor manufacturing processes, from which individual LEDs 16 are formed. In some embodiments, the LEDs can emit different colors or wavelengths during operation, as shown here by different shades of color. The LEDs are formed with at least a flat bottom and / or top surface, for example to facilitate mounting or transfer. As part of the manufacturing process, the LEDs 16 can be mechanically separated from the wafer 12. This is done by removing a so-called sacrificial layer, and possibly adding one or more release layers.

[0037] FIG. 1B shows how the elastomeric stamp 18 moves vertically from above towards the wafer 12 and adheres to the surface of the LED 16 by means of a suitable surface texture of the elastomeric stamp 18. For example, the maximum tensile force may be proportional to the size of the surface of the LED 16. This adhesion force can be produced, for example, by a silicone material, in particular a so-called PDMS elastomer. As the LED 16 is separated from the wafer 12, the LEDs can be lifted up together from the wafer 12 while they remain attached to the elastomeric stamp 18. This elastomeric stamp 18 is now moved away from the wafer 12 in a transfer operation, for example towards the support surface 14 of a display located next to it. This can be done, for example, by means of a transfer tool, so that the elastomeric stamp 18 can be considered as part of such a tool.

[0038] In Fig. 1C, the elastomeric stamp 18 is initially positioned above the support surface 14 and is lowered onto the surface of the support surface 14 in a downward motion, whereby the underside of the LEDs 16 comes into mechanical contact with the support surface 14. In a subsequent step shown in Fig. 1D, the LEDs 16 are detached from the elastomeric stamp 18. The elastomeric stamp 18 is then moved upwards, for example to start a new transfer cycle. The LEDs 16 can be permanently attached to the support surface 14 by, for example, an adhesive process.

[0039] 1A-1D, it can be seen that due to the large number of LEDs 16, a reliable and accurate positioning in the shortest possible time is desirable. In particular, when the LEDs 16 are picked up by the stamp 18, it may be desirable to achieve low forces on the one hand and reliable positioning and retention of the LEDs 16 on the wafer 12 on the other hand. In particular, avoiding adhesion fluctuations and excessive adhesion to the wafer and / or stamp can provide a significant improvement in this case.

[0040] Referring again to figures 1 and 2, these show further configurations of the carrier structure 10 according to some principles proposed to avoid breaking edges and improve lift-up. In principle, it corresponds to the basic structure depicted in figure 1A. In particular, the wafer depicted in figures 1A and 1B includes the wafer structure shown below, with figure 2 relating to a simplified plan view of the wafer 12 from above. In this example, three LEDs 16 can be seen arranged side by side, each in the form of a flat rectangle. In this respect, other forms of chips, for example hexagonal, are also possible. A large number of such side-by-side LEDs 16 may be arranged on the wafer 12, for example on an area of ​​16 or 18 inches.

[0041] Before the transfer process, these LEDs 16 are arranged on the wafer 12 in a mechanically detachable manner, meaning that they can be removed with a stamping tool 18. In the example shown here, the LEDs 16 are partially cut off from the wafer 12 at their underside (not shown) and are then held by the pick-up elements 20. The pick-up elements, which appear round here through the plan view, may for example be manufactured in the shape of a column or pole, with a round, square or elliptical cross section, for example, from an underlying carrier substrate 22. As shown in the figure, the LED 16, which is shown here in the middle, is held in place by a total of three pick-up elements 20. In particular, the three support points allow for coplanarity, i.e. a stable flat arrangement in the same plane as the other LEDs 16 in terms of distribution of forces. Two of the pick-up elements 20 pick up two LEDs 16 each at their corners or edges.

[0042] In the following figures 3A to 3D, vertical cross-sections (see line 24 in figure 2) are shown for various possible configurations of the carrier structure 10, respectively. A wafer 12, typically a carrier material or a bonding material, serves for mechanical stabilization and as a base for picking up further components such as electrical connections or electronic control elements. A first release layer 26 is arranged vertically on top of this. The release layer 26 serves to enable a controlled delamination, i.e. a deliberate and controlled peeling of the layers from each other by a defined tensile force. Furthermore, such a layer can also serve as an etching stop layer to leave adjacent layers unchanged during the etching process. For example, the breaking process used so far in the prior art can be replaced by a peeling process that does not leave any disturbing residues on the LEDs.

[0043] Furthermore, a sacrificial layer 28, also called a sacrificial layer, is provided, because the material used for such a layer is, for example, silicon, which can be removed in a subsequent process step, for example by chemical processes, in order to separate the LED 16 from the underlying wafer 12. The LED 16 further comprises a contact pad 30, which here may comprise a semiconductor active region, for example a pn junction. By way of example, FIGS. 3A and 3B show a cross-sectional view of the LED 16 with an epitaxial layer 32, to which may further be added a second release layer 34, which is formed between the sacrificial layer 28 and the epitaxial layer 32. The second release layer 34 may be located at different locations depending on the configuration.

[0044] 3A and 3B each show a configuration in which the pickup element 20 is a pole-, column- or post-shaped protrusion that protrudes vertically from the wafer 12 between the two LEDs 16 via the sacrificial layer 28 and terminates before the epitaxial layer 32. Here, the epitaxial layer 32 tapers upwards to form a V-shaped mesa trench 38 (see these figures as well as alternatives, Figs. 3C and 3D). In Fig. 3A, the second release layer 34 reaches the side or partially the underside of the contact pad 30, whereas in Fig. 3B, the second release layer 34 terminates horizontally before the contact pad 30, and the remaining gap is filled by the sacrificial layer 28. In this case, an etching substance, for example a gas or liquid, can reach the sacrificial layer 28 through the mesa trench 38, i.e., the space between the two LEDs 16.

[0045] In FIG. 3B, the delamination layer on the exposed surface of the pick-up element is also removed by the etching process. By controlling the etching process, the amount of removal of the delamination layer can be selectively adjusted. For example, for the etching process used, the delamination layer can have a significantly lower etching rate than the sacrificial layer 28. This allows the sacrificial layer to be completely removed without the etching process excessively attacking the delamination layer or the carrier substrate. In an alternative configuration, not shown here, the etching process is also used to etch through the delamination layer to the pick-up element. In other words, the funnel-shaped cutout between the two LEDs is continuous with the pick-up element. As a result, a V- or U-shaped recess for the pick-up element is created, leaving two columns on which the LEDs rest. The depth of such etching of the pick-up element can be adjusted by the process as well. However, in general, the entire pick-up element is not etched. Rather, the pick-up element is etched only half or less of its height, so that the stability of the pick-up element is sufficiently ensured. In particular, when it is time to remove the LED, rather than the remaining column breaking off, the adhesive forces of the delamination layer are overcome and the LED is lifted away.

[0046] 3C and 3D show further configuration variants, in particular with regard to the configuration of the pick-up element 20. In this case, the pick-up element 20 runs integrally from the plane of the wafer 12 via the sacrificial layer 28 to the opposite side of the carrier structure 10. Here, the pick-up element 20 is configured with a tapered or inclined LED-holding surface 36 at its upper end, which facilitates lifting up the LED 16 and at the same time ensures a reliable fixation to the wafer 12. In FIG. 3D, according to an embodiment, the pick-up element 20 terminates vertically before the end of the epitaxial layer 32. Contact pads 30 connect the various layers inside the LED, in particular the light-emitting layer. As shown in FIGS. 3B and 3D, the contact pads 30 are in each case the lowest element in the vertical direction, so that, if necessary, they can be mechanically and therefore electrically contacted directly with electrical contact elements (not shown) on the support surface of the display or module without additional bridging solder or conductive adhesive. The contact pads 30 may have an edge length in the range of, for example, 20 to 100 μm.

[0047] Finally, Fig. 3E shows a configuration in which the pick-up element is significantly expanded and the delamination layer completely covers the surface of the pick-up element. As shown in Fig. 3C and Fig. 3D, the sacrificial layer 28 extends through the funnel-shaped region between the individual LEDs with the epitaxy 32. Each LED includes an epitaxy whose lateral dimension is larger on the light-emitting side than on the side facing the contact pad 32. In other words, the LED expands starting from the side with the contact pad 32.

[0048] The resulting cross-sectional structure is an "inverted" V-shape. A further layer 34 is applied to the surface of each face of the epitaxial layer 32, in particular the surface including the sloping sides forming the funnel and the contact pads. It acts as an etch stop and, together with the delamination layer 26, creates a defined adhesion. Now for lift-up, the sacrificial layer 28 in the V-shaped area below the LED is removed by plasma etching, gas etching or other process, leaving the tip with only its layer 34 on the delamination layer of the pick-up element.

[0049] Each of Fig. 4 and Fig. 5 shows an example of the carrier structure 10 in which 24 LEDs 16 are arranged in a matrix on a wafer (not shown). In Fig. 4, a total of 17 pickup elements 20 are shown. Some of them are arranged in the mesa trenches 38 between two adjacent LEDs 16, and some are arranged at the corners of each LED 16. This arrangement allows the total number of pickup elements 20 required to be less than the total number of LEDs 16. Furthermore, one pickup element 20 in the example shown here can support or pick up up up to four adjacent LEDs 16.

[0050] In FIG. 5, the base surface of the pickup element 20 has a rectangular or square base surface, rather than a circular one as in FIG. 4. This means that the contact area 36 where the pickup element abuts the LED 16 changes. This ensures stable pickup of the LED 16 even if the LED 16 is slightly misaligned in the x or y direction. In other words, even if the lateral misalignment is reduced, the total contact area of ​​all the contact areas 36 on the LED 16 does not change, or at least is approximately the same. Furthermore, the pickup element 20 may be located on the outer edge of the support structure 12 and may engage the outer side of the LED 16. By way of example, it can be seen that a particularly good spatial stability is obtained with exactly three support points for the same LED. Again, one pickup element 20 can support two or more adjacent LEDs 16, thus reducing the space required and therefore the cost due to multiple use. In the illustrated example, the support area is significantly enlarged compared to the chip area. In practical implementation, the support area is significantly reduced to weaken the adhesion so that the delamination layer remains on the carrier and does not peel off.

[0053] In the examples shown here, LEDs are manufactured using various semiconductor technologies. The wafer to be transferred may have contact surfaces so that electrical contacts can be made. Likewise, drive control, current sources and other elements may already be present in this wafer. The LEDs transferred in this way are then further processed in some configurations. For example, the LEDs are provided with conversion layers or light shaping elements. In principle, in these configurations, individual LEDs were transferred. However, the method is not limited to such. Likewise, the above-mentioned modules may be formed on these carrier structures, which can facilitate the transfer of such modules. In this case, the columns or carrier elements are formed once the size of the module has been determined. [Explanation of symbols]

[0054] 10 Carrier Structure 12 Wafer 14 Display support surface 5,16 Microchip 18 Stamps / Stamping Tools 20 Pickup Elements 22 Carrier Board 24 Cross section (vertical direction) 10,26 Delamination layer 28 Sacrificial Layer 30 Emitter Tip 32 Epitaxial layer 34 Second Release Tier 15,36 Microchip holding surface 38 Mesa Trench

Claims

1. A carrier structure with a flat optoelectronic component, a flat carrier substrate; At least two pick-up elements; the pick-up elements are configured to releasably hold a first optoelectronic component between the at least two pick-up elements, so that the first optoelectronic component can be moved with a defined minimum force in a direction perpendicular to the carrier structure plane, and wherein at least one of the at least two pick-up elements is configured to simultaneously hold and / or support a second optoelectronic component arranged next to it, A carrier structure having a release layer arranged between a pick-up element and an optoelectronic component, the release layer remaining on the pick-up element after the optoelectronic component has been moved.

2. 2. The carrier structure according to claim 1, wherein the pick-up elements are arranged on the carrier substrate in such a way that the optoelectronic component is held by three pick-up elements.

3. 3. The carrier structure according to claim 2, wherein at least two of the three pick-up elements are configured to hold and / or support in each case one further optoelectronic component arranged next to each other.

4. 4. The carrier structure according to claim 1, wherein the pick-up element (12) is arranged in a mesa trench of a semiconductor wafer.

5. 5. The carrier structure according to claim 1, wherein the carrier substrate and the pick-up element are constructed integrally.

6. 6. The carrier structure according to claim 1, wherein the pick-up element is configured to hold an optoelectronic component laterally and from the underside of the optoelectronic component.

7. 7. The carrier structure according to claim 1, wherein the pick-up element has an optoelectronic component holding surface that extends obliquely relative to the carrier substrate plane, such that the holding force on the optoelectronic component decreases when the optoelectronic component moves away from the pick-up element.

8. 8. The carrier structure according to claim 1, wherein at least one of the pick-up elements is configured to pick up a lateral chamfered area or a side surface of an optoelectronic component.

9. 9. The carrier structure according to claim 1, wherein the contact area between the pick-up element and the optoelectronic component is less than 1 / 20, in particular less than 1 / 50, of the total area of ​​the optoelectronic component.

10. 10. The carrier structure according to claim 1, wherein the first and second optoelectronic components are partially placed on the at least one pick-up element, and a part of the surface of the pick-up element is exposed between the first and second optoelectronic components or is raised between the first and second optoelectronic components.

11. 11. An optoelectronic component comprising a semiconductor layer stack including an active layer, said active layer being arranged on a carrier structure according to one of the preceding claims.

12. 12. An optoelectronic component according to claim 11, wherein the optoelectronic component has an outer edge region formed by a mesa trench, the active layer in the outer edge region having an increased bandgap due to quantum well intermixing.

13. 13. An optoelectronic component as claimed in claim 11 or 12, characterized in that the peripheral area comprises a protrusion arranged on the carrier structure.

14. 13. A method for transferring at least two optoelectronic components according to claim 12, the at least two optoelectronic components being arranged on a common pick-up element of a carrier, the carrier comprising a sacrificial layer on which the optoelectronic components are arranged, the method comprising: - holding the optoelectronic components with the common pick-up element by removing the sacrificial layer on which the optoelectronic components are arranged; Detaching at least one of the at least two optoelectronic components from the common pickup element; A method comprising:

Images