Method for transferring an optoelectronic component, and arrangement of optoelectronic components

Abstract

The invention relates to a transfer method for transferring optoelectronic components from a first substrate to a second substrate, comprising the following steps: providing the first substrate with a plurality of optoelectronic components arranged on the first substrate in rows and columns; providing a transfer substrate; providing a structured separating layer on a side of the optoelectronic components opposite the first substrate or on the transfer substrate, the separating layer having a plurality of regions which are spaced apart from one another and are each assigned to one of the plurality of optoelectronic components; arranging the transfer substrate opposite the plurality of optoelectronic components; pressing the transfer substrate onto the optoelectronic components such that the separating layer connects a subset of the plurality of optoelectronic components to the transfer substrate; lifting the optoelectronic components connected by means of the separating layer off from the first substrate; arranging the transfer substrate with the optoelectronic components connected by means of the separating layer at a distance from the second substrate; and detaching the optoelectronic components connected by means of the separating layer from the transfer substrate by means of a LIFT process in such a way that the detached optoelectronic components fall onto the second substrate at a desired distance from one another.

Description

[0001] METHOD FOR TRANSFERRING AN OPTOELECTRONIC COMPONENT AND

[0002] ARRANGEMENT OF OPTOELECTRONIC COMPONENTS

[0003] The present application claims priority from German patent application No. 10 2024 118 165 . 6 of 27 June 2024, the disclosure content of which is hereby incorporated into the present application by reference.

[0004] The present invention relates to a method for transferring at least one optoelectronic component, in particular pLEDs. The present invention also relates to an array of such optoelectronic components arranged on an intermediate carrier.

[0005] BACKGROUND pLEDs are optoelectronic devices with lateral dimensions ranging from a few pm to about 40 pm. Such devices offer a wide variety of applications, including, but not limited to, displays for VR or AR glasses.

[0006] LEDs and pLEDs are typically processed in arrays of several thousand components and then transferred from their growth substrate or an intermediate carrier to a target substrate (e.g., a display backplane). The transfer process is delicate due to the small size of the components and the inability to reposition them after placement. Therefore, these optoelectronic components are usually processed in such a way that they are fixed to a substrate only at defined points by a tether structure. These tether structures are designed and positioned so that they can break easily during mass transfer of the components, for example, by stamping or other transfer methods. The tether structure is typically formed using a sacrificial layer, which is removed, leaving behind the tether structure on which the components to be transferred rest.Disadvantages that can arise with a classic stamping method include the required adhesive forces between the stamp and the component(s), which must be greater than the holding force between the component(s) and the holding structure, while simultaneously the adhesive forces between the stamp and the component(s) must be smaller than the adhesive force between the component(s) and a target substrate. Especially for very small components like pLEDs, it can be difficult to ideally adjust this force ratio, which in turn increases the reject rate and / or accuracy using such a classic stamping method.

[0007] Another possibility is therefore to transfer the LEDs or pLEDs onto a target substrate using a laser transfer process. However, this usually requires additional processes to transfer the LEDs or pLEDs onto a suitable substrate, or to prepare the LEDs or pLEDs for such a laser transfer process using complex procedures, which increases the complexity of the entire process chain.

[0008] The aim of the proposed principle is therefore to promote an improved method for transferring at least one optoelectronic component, in particular pLEDs, which at least partially overcomes the aforementioned disadvantages.

[0009] SUMMARY OF THE INVENTION

[0010] This need is addressed by the subject matter of the independent patent claims. Further developments and embodiments of the proposed principle are specified in the dependent claims.

[0011] The inventors propose a method for transferring optoelectronic components in which a structured release layer is placed between the optoelectronic components and a transfer layer transparent to UV light. For this purpose, a laser release material is applied directly to a structured transfer stamp or in a structured manner to the pLED surfaces to be contacted by the stamp. The structured release layer is adapted to the shape and protrusions of a stamp or forms the protrusions themselves, by means of which a desired subset of pLEDs is to be lifted from a wafer. The method is intended to combine the advantages of a stamping process and a laser-induced forward transfer (LIFT) process.This makes it possible to lift a large number (several million) of pLEDs in parallel from a wafer using a stamp, and then selectively transfer the pLEDs directly from the transfer stamp to a target substrate using a LIFT process. The structured separating layer positioned between the optoelectronic components and the UV-transparent stamp creates a defined contact area that is laterally limited to the size of the pLEDs. This allows for the selective lifting of pLEDs from a wafer and also the selective removal of pLEDs from the stamp.

[0012] Advantages of such a combination of a transfer stamp and a LI FT Release Layer can include, for example:

[0013] Both transfer methods can be implemented within a single chip flow.

[0014] A contact surface between the release layer and the pLED surfaces can be defined by structuring the release layer.

[0015] The stamp material can be chosen to provide the desired elasticity for the pLED transfer in order to prevent damage to the pLEDs.

[0016] The preparation effort for laser transfer can be reduced.

[0017] According to a first aspect, a transfer procedure for transferring optoelectronic components from a first substrate to a second substrate comprises the following steps:

[0018] Providing the first substrate with a large number of optoelectronic components arranged in rows and columns on the first substrate;

[0019] Providing a transfer substrate; providing a structured separating layer on a side of the optoelectronic devices opposite the first substrate or on the transfer substrate, wherein the separating layer has a plurality of spaced-apart regions, each of which is assigned to one of the plurality of optoelectronic devices;

[0020] Arranging the transfer substrate opposite the multitude of optoelectronic components;

[0021] Pressing the transfer substrate onto the optoelectronic components in such a way that the separating layer connects a subset of the multitude of optoelectronic components to the transfer substrate;

[0022] Lifting the optoelectronic components connected by means of the separating layer from the first substrate;

[0023] Arranging the transfer substrate with the optoelectronic components connected by means of the separating layer at a distance from the second substrate; and

[0024] Detaching the optoelectronic components connected by the separating layer from the transfer substrate using a LIFT process, such that the detached optoelectronic components fall onto the second substrate at a desired distance from each other.

[0025] The optoelectronic components can be formed, in particular, by optoelectronic devices such as p-LEDs. p-LEDs can be light-emitting diodes (LEDs) designed to emit light of a desired wavelength and which have particularly small dimensions. For example, p-LEDs can have edge lengths of less than 100 pm, less than 50 pm, or less than 10 pm and an emission area of ​​less than 0.01 mm². 2 , less than 2500pm 2 or less than 100pm 2The optoelectronic components can, however, also be formed by other optoelectronic components such as sensors or p-sensors, or electronic components such as integrated circuits (ICs) or microintegrated circuits (p-ICs) can be transferred using the proposed method instead of optoelectronic components. For the sake of simplicity, the following text will nevertheless refer to optoelectronic components. According to some aspects, the transfer substrate is transparent, in particular transparent to light in the UV range. For example, the transfer substrate can comprise or be formed by a glass, such as quartz glass. Alternatively or additionally, the transfer substrate can also comprise or be formed by sapphire, or the transfer substrate can comprise or be formed by PDMS.In particular, the transfer substrate comprises a material that is transparent, especially to light in the UV range. This design makes it possible to detach the optoelectronic components contacted by the separating layer from the separating layer using a LIFT process by irradiating through the transfer substrate.

[0026] In some respects, the transfer substrate includes an additional elastic layer on the side facing the optoelectronic components. For example, this additional layer can be a silicone layer. Such a layer allows for a relatively more elastic material / stamping material to be applied to a relatively stiffer support layer, enabling the optoelectronic components to be lifted from the primary substrate. The increased elasticity helps to ensure that pressing down on the transfer substrate does not, or at least reduces the risk of, damage to the optoelectronic components.

[0027] According to several aspects, the multitude of optoelectronic components are grown on the first substrate. The first substrate can be the growth substrate for the multitude of optoelectronic components, for example, in the form of a wafer. The optoelectronic components are arranged in rows and columns on the first substrate. Specifically, the optoelectronic components are arranged on the first substrate in a way that is most advantageous for their fabrication. For example, the optoelectronic components on the first substrate can be laterally separated from each other by a mesa etching process. However, it is also conceivable that the first substrate is a substrate onto which the optoelectronic components were rebonded during their fabrication.

[0028] In some respects, the separating layer includes a light-absorbing layer. A light-absorbing layer is characterized, in particular, by being either opaque or only slightly transparent to light of a specific wavelength (n), instead absorbing light of that wavelength (n). Due to this light absorption, the light-absorbing layer can heat up locally in the area of ​​irradiation, which can lead to local expansion, outgassing, or even local decomposition of the light-absorbing layer in that area. Accordingly, the light-absorbing layer can also be called a decomposition layer in some respects. For example, the light-absorbing layer may be formed by or comprise an acrylate or a polyimide material.

[0029] In some respects, the separating layer comprises a light-absorbing layer, a first adhesive layer, and a second adhesive layer, with the light-absorbing layer positioned between the first and second adhesive layers. Such a separating layer can also be called a DRL. The separating layer can adhere to the transfer substrate, for example, via the first adhesive layer, while optoelectronic components can adhere to the second adhesive layer.

[0030] From several perspectives, the step of providing the transfer substrate includes providing a transfer substrate with raised areas, where the raised areas are spaced apart and each is assigned to one of the plurality of optoelectronic components. In particular, the transfer substrate can have a structure on a side facing the optoelectronic components that forms the raised areas. The raised areas can be designed or selected such that they are assigned to only a subset of the plurality of optoelectronic components, and in particular, are spaced further apart than the plurality of optoelectronic components on the first substrate.In particular, the raised areas can serve to ensure that only a subset of the numerous optoelectronic components are lifted from the first substrate by means of the transfer substrate, especially at a greater distance from each other than they are arranged on the first substrate. The raised areas serve to ensure that only the optoelectronic components to be lifted are contacted, and that no contact is made with the remaining optoelectronic components located between the raised areas.

[0031] In some respects, the raised areas are formed by an additional layer on the transfer substrate, specifically a silicone layer. Such a layer allows for a relatively more elastic material / stamp material to be provided on a relatively stiffer support layer, enabling the optoelectronic components to be lifted from the primary substrate. The increased elasticity helps to prevent, or at least significantly reduce, damage to the optoelectronic components when pressing down on the transfer substrate. Furthermore, the creation of the raised areas in the additional layer is simpler compared to a support layer, and / or the support layer can be reused multiple times for this process, while the additional layer can be removed and recreated for a new process.

[0032] From several perspectives, the step of providing the structured separating layer involves applying the separating layer to the transfer substrate, particularly to the raised areas of the transfer substrate, for example by means of spin coating. The separating layer material can be applied over a large area on one of the surfaces facing the optoelectronic components and subsequently structured, or it can be applied locally to desired areas, especially to raised areas of the transfer substrate.

[0033] Additionally or alternatively, it is also possible that the step of providing the structured separating layer includes pretreatment of the transfer layer, in particular the protrusions of the transfer layer, whereby the pretreatment leads in particular to the better adhesion of the areas of the structured separating layer, which are each assigned to one of the multitude of optoelectronic components, to the formation of material accumulations of the separating layer, which in turn form the areas of the structured separating layer, which are each assigned to one of the multitude of optoelectronic components, or

[0034] Areas between the areas of the structured separating layer, each of which is assigned to one of the multitude of optoelectronic components, are repellent to the material of the separating layer.

[0035] The pretreatment can include, for example, a hydrophilic surface treatment or an adjustment of the surface energy, or it can be formed by such a process.

[0036] According to some aspects, structuring the separating layer creates raised areas that form the spaced-apart regions of the separating layer, each corresponding to one of the multitude of optoelectronic components. In particular, a separating layer can be applied over a surface area to a substantially flat surface of the transfer substrate, and the structuring of the separating layer can be achieved by exposing raised areas of the separating layer, for example, by etching into it. The formation of raised areas can be understood to mean that a continuous portion of the separating layer remains on the side of the separating layer facing the transfer substrate; that is, the separating layer is not removed across its entire thickness to form the raised areas.

[0037] Depending on several aspects, the separating layer is structured such that areas of the separating layer are completely removed, leaving free-standing areas on the transfer substrate, each associated with one of the numerous optoelectronic components. Alternatively, corresponding areas of the transfer substrate can also be removed in this step, resulting in a transfer substrate with numerous raised areas, each supporting one of the spaced-apart areas of the separating layer.

[0038] Following several steps, the separation layer is structured using an initial LIFT process, which creates the spaced areas of the separation layer. For this purpose, a continuous separation layer can be applied to a substantially flat surface of the transfer substrate. Using this initial LIFT process, bubbles can be created between the separation layer and the transfer substrate, or within the separation layer itself. These bubbles form raised areas within the separation layer, which in turn define the spaced areas of the separation layer. Optionally, cavities filled with separation layer material can be provided at appropriate locations in the transfer layer. This ensures a larger accumulation of separation layer material in the area where the raised areas are to be created, thus simplifying the process.The step of detaching the optoelectronic components connected via the separating layer from the transfer substrate can then be carried out by means of a second LIFT process. In particular, the second LIFT process causes the bubbles between the separating layer and the transfer substrate, or within the separating layer itself, to enlarge, such that the desired optoelectronic components detach from the separating layer.

[0039] From several perspectives, the step of providing the structured separating layer involves applying the layer to the opposite sides of the optoelectronic components on the first substrate in a structured manner, specifically in such a way that areas between the optoelectronic components remain free. In particular, it may additionally or alternatively be possible to apply the separating layer not (only) to the transfer substrate but (also) to the optoelectronic components themselves in a structured manner, and then, using a transfer substrate with raised areas, to detach and transfer only a subset of the many optoelectronic components. In general, the raised areas of the transfer substrate and / or the areas or raised areas of the separating layer ensure that only a subset of the many optoelectronic components on the first substrate can be transferred using the transfer substrate.the separating layer is contacted, and in particular, adjacent optoelectronic components on the first substrate are not contacted simultaneously. The total height of the protrusions of the transfer substrate and / or the areas or protrusions of the separating layer is selected such that it is ensured that optoelectronic components which are not to be lifted from the first support are not contacted by the transfer substrate or the separating layer, even if the protrusions of the transfer substrate and / or the areas of the separating layer deform due to a certain contact pressure on the optoelectronic components. At the same time, the total height of the protrusions of the transfer substrate and / or the areas or...The elevations of the separating layer are selected such that, despite a certain contact pressure of the transfer substrate on the optoelectronic components, the elevations of the transfer substrate and / or the areas of the separating layer do not deform excessively. A possible maximum value for the total height of the elevations of the transfer substrate and / or the areas or elevations of the separating layer can correspond to the lateral extent of an area of ​​the separating layer. The total height of the elevations of the transfer substrate and / or the areas or elevations of the separating layer should therefore not exceed the width or length of the elevations of the transfer substrate or the areas / elevations of the separating layer. A minimum value for the total height of the elevations of the transfer substrate and / or the areas or elevations of the separating layer can be determined by a specific design.The height of the separation layer can depend on the elasticity of the chosen materials and the contact pressure of the transfer substrate on the optoelectronic components. In particular, a minimum value for the overall height can range from 3 pm to 10 pm.

[0040] According to several aspects, the detachment step, particularly the LIFT process, creates a bubble between the transfer substrate and the optoelectronic component being detached, causing the optoelectronic component to detach from the transfer substrate or the separating layer. Specifically, local irradiation of the separating layer can cause a bubble to form in the irradiated area between the transfer substrate and the optoelectronic component, thus altering, particularly reducing, the contact area between the separating layer and the optoelectronic component, and causing the optoelectronic component to detach from the separating layer. The separating layer can, for example, be formed by a DRL according to the aspects mentioned above.

[0041] According to some considerations, the detachment step, particularly through the LIFT process, decomposes the interface between the transfer substrate and the optoelectronic device being detached, causing the optoelectronic device to detach from the transfer substrate or the interface. Specifically, local irradiation of the interface can decompose or substantially decompose it in the irradiated area between the transfer substrate and the optoelectronic device, thus altering, particularly reducing or removing, the contact area between the interface and the optoelectronic device, and causing the optoelectronic device to detach from the interface.

[0042] From some perspectives, the detachment step involves the simultaneous removal of multiple optoelectronic components. Specifically, using the LIFT method / process, several optoelectronic components can be simultaneously detached from the transfer substrate or separating layer by irradiating multiple areas. Alternatively, it is also possible to detach the optoelectronic components sequentially from the transfer substrate or separating layer.

[0043] From several perspectives, the optoelectronic components detached from the separating layer and transferred to the second substrate exhibit a different spacing on the second substrate than the optoelectronic components arranged in rows and columns on the first substrate. The spacing on the second substrate may, for example, correspond to a desired pixel pitch on the second substrate, whereas the spacing of the optoelectronic components on the first substrate may be very small, in particular a spacing at which the optoelectronic components on the first substrate were fabricated. The spacing of the optoelectronic components on the second substrate may be larger, and in particular many times larger, than the spacing of the optoelectronic components on the first substrate.

[0044] From some perspectives, the step of lifting the optoelectronic components connected by the separating layer from the first substrate involves the selective lifting of optoelectronic components, such that the lifted optoelectronic components on the transfer substrate have a different spacing from each other than the optoelectronic components arranged in rows and columns on the first substrate. For example, in a first step, only every second, third, fourth, or subsequent optoelectronic component per row and column can be lifted from the first substrate, so that the spacing between the optoelectronic components on the transfer substrate is different, and in particular greater, than the spacing of the optoelectronic components on the first substrate.

[0045] In some respects, the selective detachment of optoelectronic components involves the selective removal of optoelectronic components from the first substrate using laser light selectively directed through the first substrate. By (simultaneously) irradiating only each second, third, fourth, or other optoelectronic component per row and column on the first substrate, particularly through the first substrate, selectively chosen optoelectronic components can be detached from the first substrate by means of the transfer substrate or the separating layer and transferred to the second substrate.

[0046] According to another aspect, an optoelectronic arrangement comprises a transfer substrate transparent to light, particularly to light in the UV range, a plurality of optoelectronic components arranged in rows and columns on the transfer substrate, and a structured separating layer between the optoelectronic components and the transfer substrate. The separating layer has a plurality of spaced-apart regions, each corresponding to one of the

[0047] a large number of optoelectronic components are assigned to it and has at least one light absorption layer which decomposes at least partially under the influence of light, especially light in the UV range.

[0048] The optoelectronic arrangement can, for example, be an intermediate product of the method according to the invention, namely an arrangement comprising the transfer substrate, the structured separating layer, and the optoelectronic components arranged on the separating layer, after these have been lifted from the first substrate and before they are transferred to the second substrate. Accordingly, the aspects described above for the method can also be applied to the optoelectronic arrangement.

[0049] In some respects, the transfer substrate includes an additional elastic layer on the side facing the optoelectronic components. For example, this additional layer can be a silicone layer. Such a layer allows for a relatively more elastic material / stamping material to be applied to a relatively stiffer support layer, enabling the optoelectronic components to be lifted from the primary substrate. The increased elasticity helps to ensure that pressing down on the transfer substrate does not, or at least reduces the risk of, damage to the optoelectronic components.

[0050] According to some views, the transfer substrate comprises a multitude of raised areas, each spaced apart and each associated with one of the multitude of optoelectronic components. In particular, the transfer substrate may have a structure on a side facing the optoelectronic components that forms the raised areas. According to some views, the raised areas are formed by an additional layer on the transfer substrate, especially a silicone layer. According to some views, the separating layer comprises a multitude of raised areas that form the spaced regions of the separating layer. For example, the raised areas may be formed by a bubble or bubbles between the separating layer and the transfer substrate, or within the separating layer itself.Optionally, cavities can be provided at appropriate locations in the transfer layer, which are filled with material from the separation layer, so that in the area where the protrusions or areas of the separation layer are to be created there is a larger accumulation of material from the separation layer, which simplifies the creation of the protrusions or areas of the separation layer.

[0051] BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Further aspects and embodiments according to the proposed principle will be revealed in relation to the various embodiments and examples, which are described in detail in conjunction with the accompanying drawings.

[0053] Figures 1A to ID show steps of a transfer procedure according to some aspects of the proposed principle;

[0054] Figures 2A to 2D show steps of a further embodiment of a transfer process according to some aspects of the proposed principle;

[0055] Figures 3A to 3D show steps of a further embodiment of a transfer process according to some aspects of the proposed principle;

[0056] Figures 4A to 4D show steps of a further embodiment of a transfer process according to some aspects of the proposed principle;

[0057] Figures 5A to 5E show steps of a further embodiment of a transfer method according to some aspects of the proposed principle; and Figures 6A to 6D show steps of a further embodiment of a transfer method according to some aspects of the proposed principle.

[0058] DETAILED DESCRIPTION

[0059] The following embodiments and examples illustrate various aspects and their combinations according to the proposed principle. The embodiments and examples are not always to scale. Likewise, various elements may be enlarged or reduced to highlight individual aspects. It is understood that the individual aspects and features of the embodiments and examples shown in the figures can readily be combined without affecting the principle of the invention. Some aspects have a regular structure or shape. It should be noted that in practice, minor deviations from the ideal shape may occur without contradicting the inventive idea.

[0060] Furthermore, the individual figures, features, and aspects are not necessarily depicted at the correct size, and the proportions between the individual elements may not be entirely accurate. Some aspects and features are emphasized by being shown enlarged. However, terms such as "above," "below," "below," "larger," "smaller," and the like are correctly represented in relation to the elements in the figures. Thus, it is possible to deduce such relationships between the elements from the illustrations.

[0061] Figures 1A to ID each show a side view of steps of a transfer process for transferring optoelectronic components 2 from a first substrate 3 to a second substrate according to some aspects of the proposed principle.

[0062] In a first step, as shown in Fig. 1A, a transfer substrate 4 with a silicone layer 5 arranged on it is provided. The transfer substrate 4 is made of a transparent material, such as glass or sapphire, so that optoelectronic components 2 adhering to a separating layer 6 can later be detached from the separating layer 6 by means of laser light L radiated through the transfer substrate 4.

[0063] The transfer substrate 4, or the silicone layer 5, has a plurality of protrusions 9 designed to contact and lift off a corresponding plurality of optoelectronic components 2 from a first substrate 3. The protrusions are spaced apart from each other such that the distance between the protrusions 9 is greater than the distance between optoelectronic components 2 on a first substrate 3, in particular by a multiple of a factor of 10.

[0064] Subsequently, the upper surfaces 10 of the protrusions 9 are pretreated by means of a hydrophilic surface treatment so that a subsequently applied structured release layer 6 (shown in Fig. 1B) adheres better to the upper surfaces 10 than in the areas between the protrusions 9. The release layer 6 can, for example, be applied over a large area to the transfer substrate 4 or the silicone layer 5 with its protrusions 9 by means of spin coating and then structured. This results in a multitude of spaced-apart areas 8 of the structured release layer 6, the spacing and arrangement of which essentially correspond to the spacing and arrangement of the protrusions 9.

[0065] The separating layer 6 is specifically designed to allow optoelectronic components 2 to adhere to it when the separating layer 6 is pressed onto a top surface of optoelectronic components 2, and is specifically designed to allow optoelectronic components 2 adhering to the separating layer 6 to be detached from the separating layer 6 again by means of laser light L. The separating layer 6 can be, for example, a DRL or a decomposition layer. Various arrangement rates and configurations of the separating layer 6 will be discussed below. Subsequently, as shown in Fig. IC, a first substrate 3 with a plurality of optoelectronic components 2 arranged in rows and columns is provided. The optoelectronic components can, in particular, be p-LEDs that have been fabricated on the first substrate 3.The first substrate 3 can, for example, be the growth substrate / fabrication wafer of the optoelectronic components 2. The optoelectronic components are arranged in rows and columns on the first substrate 3. In particular, the optoelectronic components 2 are arranged on the first substrate 3 in such a way as can result from the fabrication of the optoelectronic components 2 on the first substrate 3.

[0066] The transfer substrate 4, with its raised areas 9 and the structured separating layer 6 regions arranged thereon, is then pressed onto the optoelectronic components 2 on the first substrate 3, such that the separating layer 6, or rather the regions 8 of the separating layer 6, contacts a subset of the multitude of optoelectronic components 2 and thus bonds them to the transfer substrate 6. For this purpose, the separating layer 6 exhibits sufficient tackiness to generate an adhesive force between the transfer substrate 4 and the optoelectronic components 2, enabling them to be lifted from the first substrate 3.

[0067] In a subsequent step, the optoelectronic components 2 adhering to the separating layer 6 are lifted from the first substrate 3. For this purpose, the transfer substrate 4, with the separating layer 6 and the optoelectronic components 2 located thereon, is lifted from the first substrate 3. Specifically, a subset of the multitude of optoelectronic components 2 is lifted from the first substrate 3 by means of the transfer substrate 4 and the separating layer 6 located thereon. Alternatively, the optoelectronic components 2 can also be lifted by pulling the first substrate 3 downwards. The resulting "intermediate product" according to Fig. IC corresponds to an optoelectronic arrangement 1 according to some aspects of the proposed principle. The optoelectronic arrangement 1 can be used to populate a second substrate with optoelectronic components 2, as described below.

[0068] As shown in Fig. ID, the optoelectronic components 2, contacted via the separating layer 6, are arranged at a distance from a second substrate. Using a LIFT process, the optoelectronic components 2 contacted via the separating layer 6 are then detached from the separating layer 6, such that the detached optoelectronic components 2 are transferred to the second substrate at a desired distance from each other, in particular by falling from the transfer substrate 4 onto the second substrate. For this purpose, the optoelectronic components 2, or rather the separating layer 6 between the optoelectronic components 2 and the transfer substrate 4, are locally irradiated with laser light L through the transfer substrate 4, so that the optoelectronic components 2 detach from the separating layer 6 and are transferred to the second substrate.The laser light L could, for example, be pulsed laser light in the UV range.

[0069] The separating layer 6, and in particular a light absorption layer present in or forming the separating layer, is locally irradiated with laser light L, especially laser light pulses in the UV range, so that the light absorption layer expands locally, outgasses locally, or even decomposes locally in the irradiated area. This causes a bubble to form in the irradiated area between the transfer substrate 4 and a corresponding optoelectronic device 2, or the separating layer 6 to decompose completely, causing the optoelectronic device 2 to detach. The detached optoelectronic device 2 then falls from the transfer substrate 4 onto the second substrate.

[0070] This step can then be repeated for further optoelectronic components 2 until the second substrate is completely populated, or no more optoelectronic components 2 adhere to the transfer substrate 4. It is also possible for several optoelectronic components 2 to be simultaneously detached from the transfer substrate 4 using the method described and transferred to the second substrate at the same time.

[0071] The optoelectronic components 2, detached from the separating layer 6 and transferred to the second substrate, may have a different spacing between them on the second substrate than the optoelectronic components 2 arranged in rows and columns on the first substrate 3. The spacing on the second substrate may, for example, correspond to a desired pixel pitch on the second substrate, whereas the spacing of the optoelectronic components 2 on the first substrate 3 may be very small, in particular a spacing with which the optoelectronic components 2 were fabricated on the first substrate 3. The spacing of the optoelectronic components 2 on the second substrate is larger, in particular many times larger, than the spacing of the optoelectronic components 2 on the first substrate 3.

[0072] Figures 2A to 2D show steps of a further embodiment of a transfer process according to some aspects of the proposed principle.

[0073] In contrast to the process steps shown in Figures 1A to 1ID, the upper surfaces 10 of the protrusions 9 are pretreated such that the surface energy of the upper surfaces 10 is adapted to the requirements of the structured separating layer 6. In particular, the surface energy of the upper surfaces 10 can, for example, be adapted such that dome-shaped areas 8 of the separating layer 6 are formed on the upper surfaces 10 of the protrusions 9. Compared to the embodiment shown in Figures 1A to 1ID, such a design can be advantageous because a more homogeneous bonding layer can result when the transfer substrate 4 is compressed with the optoelectronic components 2, especially when using a thin separating layer 6. Furthermore, the formation of air inclusions in the separating layer 6 can be prevented with the embodiment shown.between separating layer 6 and optoelectronic components 2 and / or between separating layer 6 and the protrusions 9 are reduced.

[0074] The resulting “intermediate product” according to Fig. 2D corresponds in turn to an optoelectronic arrangement 1 according to some aspects of the proposed principle. The optoelectronic arrangement 1 can be used to equip a second substrate with optoelectronic components 2, as already described for Fig. ID.

[0075] Figures 3A to 3D show steps of a further embodiment of a transfer process according to some aspects of the proposed principle.

[0076] In contrast to the process steps shown in Figures 1A to ID and 2A to 2D, the protrusions 9 are formed directly in the transfer substrate 4 without an additional silicone layer. According to one of the embodiments described above, the upper surfaces 10 of the protrusions 9 can be pretreated according to the requirements of the separating layer 6. In particular, this ensures that accumulations of material from the separating layer 6, which form the areas 8 on the protrusions 9, are either completely separated from one another or are still somewhat connected by residual material between the protrusions 9. By appropriately selecting the height of the protrusions 9, however, it can be ensured that excess material from the separating layer 6 can remain between the protrusions 9 without hindering or interfering with the further transfer process of the optoelectronic components 2.Rather, in some aspects it may even be advantageous if the areas 8 of the separating layer 6 are still connected in order to increase the overall stability of the separating layer 6 when the optoelectronic components 2 are lifted from the first substrate 3.

[0077] Figures 4A to 4D show steps of two further embodiments of a transfer process based on some aspects of the proposed principle. In these embodiments, the raised areas for contacting only a subset of the optoelectronic components 2 are not formed by the transfer substrate 3 or a silicone layer located thereon, but by the separating layer 6 itself. For this purpose, in a first step (see Figures 4A and 4B), a separating layer 6 is applied over a large area to a transfer substrate 4, and by means of a first LIFT process, bubbles B are generated at desired locations on the separating layer between the separating layer and the transfer substrate and / or within the separating layer 6. These bubbles form the raised areas 7 and the regions 8, respectively, which are subsequently brought into contact with the optoelectronic components 2 to be lifted off.As shown in Figure 4B, cavities 11 can be provided at the corresponding positions in the transfer substrate 4, which are filled with the material of the transfer layer 6. This ensures that sufficient material is available at the corresponding positions to enable the generation of bubbles B for the creation of the elevations 7.

[0078] The steps shown in Figures 4C and 4D then essentially correspond to the steps already described, wherein the separating layer 6, as shown in Figure 4D, is not completely decomposed during a second LI FT process for detaching the optoelectronic components 2, but only larger bubbles are formed, so that the optoelectronic components 2 detach and fall onto the second substrate.

[0079] Figures 5A to 5E show steps of two further embodiments of a transfer process based on some aspects of the proposed principle. In these processes, a separating layer 6 is applied over a large area to a substantially flat transfer substrate and subsequently structured. Figure 5A shows an embodiment in which the separating layer 6 is structured such that it has continuous protrusions 7, whereas in the embodiment shown in Figure 5B, the separating layer 6 is structured throughout its entirety, extending into a silicone layer 5 applied to the transfer substrate 4. Such structuring can be carried out, for example, using known etching techniques (post-chemical, dry chemical, plasma etching, etc.).The structuring results in regions 8 of the separating layer 6, which are designed to come into contact with a subset of the multitude of optoelectronic components 2 on the first substrate 3. Other embodiments, not shown, include the separating layer being applied directly to the transfer substrate and the separating layer being structured up to the transfer substrate or only up to the silicone layer. It is also possible to provide the structure shown in Figure 5A on the transfer substrate, for example by means of molding or 3D printing, or to transfer a prefabricated separating layer onto the transfer substrate.

[0080] Figures 6A to 6D show steps of two further embodiments of a transfer process based on some aspects of the proposed principle. In contrast to the previous embodiments, the separating layer 6 is not applied to the transfer substrate or a silicone layer, but rather to a top surface of the optoelectronic components 2 opposite the first substrate 3. According to Figure 6A, a first substrate 3 is provided with a plurality of optoelectronic components 2 arranged in rows and columns. The optoelectronic components can, in particular, be p-LEDs that have been fabricated on the first substrate 3. The first substrate 3 can, for example, be the growth substrate / fabrication wafer of the optoelectronic components 2. The optoelectronic components are arranged in rows and columns on the first substrate 3.In particular, the optoelectronic components 2 are arranged on the first substrate 3 in such a way as can result from the fabrication of the optoelectronic components 2 on the first substrate 3. In addition, a structured separating layer 6 has been provided on the top surfaces of the optoelectronic components 2 during the fabrication process, such that separate areas 8 of the separating layer 6 are each arranged on and assigned to the optoelectronic components 2.

[0081] A transfer substrate 4 with a silicone layer 5 arranged on it is then provided. The transfer substrate 4 is made of a transparent material, such as glass or sapphire, so that optoelectronic components 2 adhering to a separating layer 6 can later be detached from the separating layer 6 by means of laser light L shone through the transfer substrate 4. The transfer substrate 4, or the silicone layer 5, has a plurality of protrusions 9 which are designed to contact and detach a corresponding plurality of optoelectronic components 2 from a first substrate 3. The protrusions are spaced apart from each other such that the distance between the protrusions 9 is greater than the distance between optoelectronic components 2 on a first substrate 3, in particular by a multiple of a distance between optoelectronic components 2 on a first substrate 3.

[0082] The transfer substrate 4 with the protrusions 9 is then pressed (see Figure 6B) onto the optoelectronic components 2 on the first substrate 3 or onto the areas 8 of the separating layer 6, such that the protrusions 9 contact a subset of the plurality of optoelectronic components 2 or areas 8 of the separating layer 6, and this subset of the plurality of optoelectronic components 2 is connected to the transfer substrate 6 by means of the intervening areas 8 of the separating layer 6. For this purpose, the separating layer 6 has a sufficient adhesiveness to generate an adhesive force between the transfer substrate 4 and the optoelectronic components 2 to lift the contacted optoelectronic components 2 from the first substrate 3.

[0083] In a subsequent step, the optoelectronic components 2 adhering to the separating layer 6 are lifted from the first substrate 3 (see Fig. 6C). For this purpose, the transfer substrate 4, with the adhering areas 8 of the separating layer 6 and the optoelectronic components 2 adhering to them, is lifted from the first substrate 3. In particular, a subset of the multitude of optoelectronic components 2 is lifted from the first substrate 3 by means of the transfer substrate 4. Alternatively, the optoelectronic components 2 can also be lifted by pulling the first substrate 3 downwards.

[0084] The “intermediate product” resulting from Fig. 6C corresponds to an optoelectronic arrangement 1 according to some aspects of the proposed principle. The optoelectronic arrangement 1 can be used to equip a second substrate with optoelectronic components 2, as described below.

[0085] As shown in Fig. 6D, the optoelectronic components 2, contacted by means of the protrusions 9, are arranged at a distance from a second substrate. Using a LIFT process, the optoelectronic components 2 contacted by means of the protrusions 9 are then detached from the transfer substrate 4, such that the detached optoelectronic components 2 are transferred to the second substrate at a desired distance from each other, in particular by falling from the transfer substrate 4 onto the second substrate. For this purpose, the optoelectronic components 2, or the separating layer 6 between the optoelectronic components 2 and the transfer substrate 4, are locally irradiated with laser light L through the transfer substrate 4, so that the optoelectronic components 2 detach from the separating layer 6 and are transferred to the second substrate.The laser light L could, for example, be pulsed laser light in the UV range.

[0086] REFERENCE MARK LIST

[0087] 1 optoelectronic arrangement 2 optoelectronic component

[0088] 3 first substrate

[0089] 4 transfer subs stepped

[0090] 5 additional layers

[0091] 6 Separation layer 7 Elevations

[0092] 8 areas

[0093] 9 surveys

[0094] 10 Top

[0095] 11 Cavity

[0096] L laser light

[0097] B bladder

Claims

PATENT CLAIMS 1. Transfer method for transferring optoelectronic components (2) from a first substrate (3) to a second substrate comprising the steps: Providing the first substrate (3) with a plurality of optoelectronic components (2) arranged in rows and columns on the first substrate (3); Providing a transfer substrate (4) ; Providing a structured separating layer (6) on a side of the optoelectronic devices (2) opposite the first substrate (3) or on the transfer substrate (4), wherein the separating layer (6) has a plurality of spaced-apart regions (8) which are each assigned to one of the plurality of optoelectronic devices (2); Arranging the transfer substrate (4) opposite the multitude of optoelectronic components (2) ; By pressing the transfer substrate (4) onto the optoelectronic components (2) such that the separating layer (6) connects a subset of the plurality of optoelectronic components (2) with the transfer substrate (6); Lifting the optoelectronic components (2) connected by means of the separating layer (6) from the first substrate (3) ; Arranging the transfer substrate (4) with the optoelectronic components (2) connected by means of the separating layer (6) at a distance from the second substrate; and Detaching the optoelectronic components (2) connected by means of the separating layer (6) from the transfer substrate (4) by means of a LIFT process, such that the detached optoelectronic components (2) fall onto the second substrate at a desired distance from each other; wherein the step of providing the structured separating layer (6) comprises applying the separating layer (6) over a surface area to the transfer substrate (4) and subsequently structuring the separating layer (6) on the transfer substrate (4).

2. Transfer method according to claim 1, wherein the step of providing the transfer substrate (4) comprises providing a transfer substrate (4) with protrusions (9) wherein the protrusions (9) are spaced apart from each other and each is assigned to one of the plurality of optoelectronic components (2).

3. Transfer method according to claim 2, wherein the protrusions (9) are formed by an additional layer (5) on the transfer substrate (4), in particular by a silicone layer.

4. Transfer method according to one of claims 2 to 3, wherein the step of providing the structured separating layer (6) comprises applying the separating layer (6) to the elevations (9) of the transfer substrate (4), in particular by means of spin coating.

5. Transfer method according to one of claims 1 to 4, wherein the step of providing the structured separation layer (6) comprises pretreating the transfer layer (4), in particular the protrusions (9) of the transfer layer (4).

6. Transfer method according to claim 5, wherein the pretreatment comprises a hydrophilic surface treatment or an adjustment of the surface energy.

7. Transfer method according to claim 1, wherein by structuring the separating layer (6) elevations (7) are formed which form the mutually spaced areas (8) of the separating layer (6).

8. Transfer method according to claim 1, wherein structuring the separating layer (6) comprises etching through the separating layer (6) and into the transfer substrate (4) such that the transfer substrate (6) has a plurality of protrusions (7) exhibits, on each of which one of the mutually spaced areas (8) of the separating layer (6) is arranged.

9. Transfer method according to claim 1 or 7, wherein the structuring of the separating layer (6) comprises a first LIFT process by means of which the spaced-apart regions (8) of the separating layer (6) are generated; and wherein the step of detaching the optoelectronic components (2) connected by means of the separating layer (6) from the transfer substrate (6) is carried out by means of a second LIFT process.

10. Transfer method according to one of claims 1 to 3, wherein the step of providing the structured separating layer (6) comprises a structured application of the separating layer (6) to the first substrate (3) opposite sides of the optoelectronic devices (2), in particular such that areas between the optoelectronic devices (2) remain free.

11. Transfer method according to any one of claims 1 to 10, wherein the transfer substrate (4) is transparent, in particular transparent to light in the UV range.

12. Transfer method according to one of claims 1 to 11, wherein the separating layer (6) comprises a light absorption layer and in particular comprises a first adhesive layer, a second adhesive layer and a light absorption layer arranged in between.

13. Transfer method according to any one of claims 1 to 12, wherein by the step of detachment, in particular by the LIFT process, a bubble (B) is created between the transfer substrate (4) and the components (2) to be detached, or the separating layer (6) between the transfer substrate (4) and the components (2) to be detached is removed, so that the optoelectronic components (2) are detached from the transfer substrate (4).

14. Transfer method according to one of claims 1 to 13, wherein the optoelectronic components (2) detached from the separating layer (6) and transferred to the second substrate have a different distance to each other on the second substrate than the optoelectronic components (2) arranged in rows and columns on the first substrate (3).

15. Transfer method according to any one of claims 1 to 14, wherein the step of lifting the optoelectronic components (2) connected by means of the separating layer (6) from the first substrate (3) comprises selective lifting of optoelectronic components (2) such that the lifted optoelectronic components (2) on the transfer substrate (4) have a different distance to each other than the optoelectronic components (2) arranged in rows and columns on the first substrate (3).

16. Optoelectronic arrangement (1) comprising: a transfer substrate (4) transparent to light, in particular to light in the UV range; a plurality of optoelectronic devices (2) arranged in rows and columns on the transfer substrate (4); and a structured separating layer (6) between the optoelectronic devices (2) and the transfer substrate (4); wherein the separating layer (6) has a plurality of mutually spaced regions (8), each of which is assigned to one of the plurality of optoelectronic devices (2); wherein the separating layer (6) has at least one light-absorbing layer which decomposes at least partially under the influence of light, in particular light in the UV range; and wherein the protrusions (9) are formed by an additional layer (5) on the transfer substrate (4), in particular by a silicone layer.

17. Optoelectronic arrangement (1) according to claim 16, wherein the transfer substrate (4) comprises a plurality of protrusions (9); and wherein the protrusions (9) are spaced apart from one another and each is associated with one of the plurality of optoelectronic components (2).

18. Optoelectronic arrangement (1) according to claim 16, wherein the separating layer (6) comprises a plurality of protrusions (7) that form the spaced-apart regions (8) of the separating layer (6); and wherein the protrusions (7) are in particular each formed by a bubble (B) between the transfer substrate (4) and the optoelectronic components (2).

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