METHOD FOR MANUFACTURING A RADIATION-EMPLOYING COMPONENT AND RADIATION-EMPLOYING COMPONENT

Abstract

A method for manufacturing a radiation-emitting component (100) is specified, comprising the following process steps: - Providing at least one semiconductor chip (10) which, during operation, emits electromagnetic radiation of a first wavelength range from a radiation emission surface (11), - Manufacturing a conversion element (20) on the radiation emission surface (11), wherein manufacturing the conversion element (20) comprises the process steps: - Applying a partially cured matrix material (21) in which phosphor particles are embedded that convert electromagnetic radiation of the first wavelength range into electromagnetic radiation of a second wavelength range, to a surface, - Compacting the partially hardened matrix material (21) to produce a compact layer (22), - Complete hardening of the compact layer (22), wherein the surface is the radiation emission surface (11) of the semiconductor chip (10) or an auxiliary substrate from which the compact layer (22) is transferred to the radiation emission surface (11) before complete curing. A radiation-emitting device (100) is further specified.

Description

[0001] A method for manufacturing a radiation-emitting component and a radiation-emitting component are described.

[0002] The object of at least one embodiment is to provide an improved method for manufacturing a radiation-emitting component. The object of at least another embodiment is to provide a radiation-emitting component with improved properties. These objects are achieved by a method and a radiation-emitting component according to the independent claims. Further embodiments and developments of the method and the component are the subject of dependent claims.

[0003] A method for manufacturing a radiation-emitting component is described. According to at least one embodiment, the method comprises the step of providing at least one semiconductor chip which, during operation, emits electromagnetic radiation of a first wavelength range from a radiation emission surface. The electromagnetic radiation of the first wavelength range thus constitutes the emission spectrum of the semiconductor chip and is also referred to as primary radiation. The radiation emission surface can also be referred to as the radiation-emitting surface.

[0004] The semiconductor chip is, for example, a light-emitting diode (LED) chip or a laser diode chip. The component can therefore be a light-emitting diode (LED) or a laser. Preferably, the semiconductor chip has an epitaxially grown sequence of semiconductor layers with an active zone suitable for generating electromagnetic radiation. For this purpose, the active zone may, for example, have a pn junction, a double heterostructure, a single quantum well, or a multiple quantum well structure.

[0005] During operation, the semiconductor chip can emit electromagnetic radiation, for example from the ultraviolet spectral range and / or from the visible spectral range, particularly from the blue spectral range. The primary radiation thus has wavelengths in the range of 400 nm to 500 nm.

[0006] According to at least one embodiment, the method further comprises the process step of manufacturing a conversion element on the radiation emission surface. Manufacturing the conversion element includes the process step of applying a partially cured matrix material, in which phosphor particles are embedded that convert electromagnetic radiation of the first wavelength range into electromagnetic radiation of a second wavelength range, to a surface.

[0007] A "partially cured matrix material" is a pre-crosslinked but still plastically deformable material. This means that the material already contains two- and / or three-dimensionally crosslinked polymer chains, which can be further polymerized and / or crosslinked under suitable external conditions. Suitable external conditions can include, for example, heat and / or pressure. Without these conditions, the pre-cured material retains its properties and does not fully cure. Such a material can also be referred to as a B-stage material. The B-stage properties, namely plastic deformability and stability against complete curing, are present in the partially cured matrix material within a specific temperature range, particularly one that includes room temperature.

[0008] The term "phosphor particle" is used here and in the following to refer to a wavelength-converting material in particle form, i.e., a material designed to absorb and emit electromagnetic radiation. Specifically, the phosphor particles absorb electromagnetic radiation with a different wavelength maximum than the electromagnetic radiation they emit. For example, the phosphor particles absorb radiation with a wavelength maximum at shorter wavelengths than the emission maximum and thus emit radiation with an emission maximum shifted towards the red end of the spectrum. Pure scattering or pure absorption are not considered wavelength-converting in this context.

[0009] According to at least one embodiment, the production of a conversion element on the radiation emission surface comprises the further process step of compacting the partially cured matrix material to produce a compact layer. Here and in the following, "compacting" refers to a measure by which any pores or cavities within the partially cured matrix material and / or between the partially cured matrix material and adjacent surfaces are removed. The resulting compact layer thus contains the partially cured matrix material in which phosphor particles are embedded and is free of pores and cavities. Furthermore, the phosphor particles in the compact layer are well enclosed by the partially cured matrix material. The compact layer also abuts adjacent surfaces without gaps.

[0010] According to at least one embodiment, the production of a conversion element on the radiation emission surface comprises the further process step of completely curing the compact layer. In this step, the previously partially cured matrix material is completely cured, i.e., fully polymerized and cross-linked, so that the actual matrix material in which phosphor particles are embedded, and thus the conversion element, is formed.

[0011] According to at least one embodiment, the surface onto which the partially cured matrix material is applied is either the radiation emission surface of the semiconductor chip or an auxiliary substrate from which the compact layer is transferred to the radiation emission surface before complete curing. In both alternatives, the conversion element is fabricated on the semiconductor chip so that it is directly integrated into the finished device, i.e., without an intervening adhesive layer on the semiconductor chip or its radiation emission surface. If the surface is the radiation emission surface, all process steps for fabricating the conversion element take place on the semiconductor chip; if the surface is an auxiliary substrate, only the complete curing of the compact layer takes place on the semiconductor chip, while the remaining steps for fabricating the conversion element are performed on the auxiliary substrate.Transferring the compact layer to the semiconductor chip involves detaching it from the auxiliary substrate and arranging it on the radiation emission surface, with the order of these steps being freely selectable.

[0012] According to at least one embodiment, a method for manufacturing a radiation-emitting component is provided, comprising the following process steps: - Providing at least one semiconductor chip which, during operation, emits electromagnetic radiation of a first wavelength range from a radiation emission surface, - Manufacturing a conversion element on the radiation emission surface, wherein the manufacturing of the conversion element comprises the following process steps: - Application of a partially cured matrix material, in which phosphor particles are embedded that convert electromagnetic radiation of the first wavelength range into electromagnetic radiation of a second wavelength range, onto a surface, - Compacting the partially cured matrix material to produce a compact layer, - Complete hardening of the compact layer, wherein the surface is the radiation emission surface of the semiconductor chip or an auxiliary substrate from which the compact layer is transferred to the radiation emission surface prior to complete hardening.

[0013] Many LEDs (light-emitting diodes) are based on a combination of a semiconductor chip and a conversion element. This element converts the radiation emitted by the semiconductor chip, for example, from the blue spectral range, into radiation of a different wavelength. Conventionally, conversion plates, made of materials such as conversion ceramics or phosphor in glass, are used. These plates must be bonded to the semiconductor chip, usually with silicone. However, silicone has low thermal conductivity, creating a thermal barrier between the conversion plate and the semiconductor chip that increases with the thickness of the layer. To keep the thickness of this adhesive layer as thin as possible, the requirements for the flatness and roughness of the conversion plate, as well as for the reproducible application of minute quantities of adhesive, are very high. Furthermore, the adhesive joint often becomes a weak point over time.

[0014] Furthermore, the matrix materials used so far in conversion plates have several disadvantages. For applications up to 150°C, silicone is conventionally used as the matrix for the phosphor. However, this has low thermal conductivity and low thermal stability, limiting applications to current densities of < 1 A / mm². 2 are limited. Conventionally used conversion ceramics with better thermal conductivity are, in turn, very limited in Ra and chromaticity due to their manufacturing process. Glass as a matrix material necessitates a high processing temperature, which can damage embedded phosphors, such as a red CASN phosphor.

[0015] Due to the direct placement and completion of the conversion element on the semiconductor chip, a thermal barrier in the form of an adhesive layer is unnecessary in the component manufactured using the method described here. This results in a component that can operate even at high currents, for example, in applications requiring high luminance, such as headlights or stage lighting. It is also suitable for so-called high-current applications with current densities exceeding 1 A / mm². 2The heat generated in the conversion element manufactured as described here can be efficiently dissipated from it to the semiconductor chip. This applies to both cool white applications with color temperatures of, for example, 5700 K or 6500 K and warm white applications at, for example, 3200 K, where a high color rendering index (CRI) of Ra ≥ 80 or even Ra ≥ 90 may be required. Such applications have a high red component in the spectrum, and typical red phosphors are particularly sensitive to high operating currents and temperatures due to their larger Stokes shift and stronger thermal quenching. A conversion element manufactured as described here exhibits sufficiently good thermal conductivity for such applications and is free of a thermal barrier caused by an adhesive layer.

[0016] The inventors further recognized that using the partially cured matrix material to manufacture the conversion element enables an adhesive-free connection between the conversion element and the semiconductor chip. Because the partially cured matrix material is fully cured directly on the semiconductor chip or its radiation-emitting surface, a direct bond is created between the conversion element and the semiconductor chip. The absence of an adhesive layer between the semiconductor chip and the conversion element, in turn, results in improved thermal bonding of the conversion element to the semiconductor chip and, simultaneously, good optical bonding.The good optical bonding is due to the fact that dosing problems, which normally occur in connection with adhesive layers, are not present, and optical losses caused by too little adhesive or by squeeze-out, i.e., too much adhesive, are avoided.

[0017] Furthermore, the inventors recognized that when using a partially cured matrix material, minimal shrinkage or volume loss occurs during full curing. This means that only minor stresses arise, and the manufactured conversion element is less or not at all susceptible to cracking. Moreover, this allows for the formation of a conversion element with crack- and gap-free surfaces and side faces. This prevents the ingress of process materials during manufacturing and of potting materials during the completion of the component, which has a positive impact on both the processing and the product. Optical losses due to ingress of material are practically non-existent in the component manufactured using the method described here.

[0018] The partially cured matrix material used in the process described here is particularly well-suited for densification. This densification results in a high phosphor particle density in the final matrix material, as well as a homogeneous distribution of the phosphor particles within the matrix material. This also allows for the production of thin conversion elements. This applies to both flat and structured conversion elements, for which the partially cured matrix material is, for example, introduced into cavities created by a photoresist. Furthermore, the homogeneous phosphor particle distribution increases the yield at the desired color location.Furthermore, the compaction process ensures good wetting and bonding of the phosphor particles to the matrix material, thus preventing voids and / or cracks in the resulting conversion element, which in turn has both optical and thermal advantages. Compacting the partially cured matrix material allows for the production of a thin conversion element with a high density of phosphor particles and low or no porosity. Such a conversion element exhibits good thermal conductivity, resulting in high efficiency and luminous efficacy in the component produced using the described method.

[0019] Due to its plastic deformability, the partially cured matrix material can be applied to the desired location and bond with the surface during the subsequent stages of the process. This makes the described process particularly simple, especially time- and cost-efficient, as a separate bonding step and the complex dosing of an adhesive are unnecessary. Overall, the process is therefore a simple procedure requiring few material components and process steps / times.

[0020] Furthermore, the method described here makes it possible to apply the partially cured matrix material directly to the radiation emission surface or temporarily to an auxiliary substrate. In the latter case, the compact layer created there can be characterized and, if necessary, discarded before being transferred to the radiation emission surface. This also saves costs, since only the compact layer, and not the semiconductor chip itself, needs to be discarded.

[0021] According to at least one embodiment, a large number of semiconductor chips are provided on a common substrate, which are then separated after complete hardening. Thus, a large number of semiconductor chips, for example those present in a wafer stack, can be simultaneously equipped with a conversion element, and after separation, a large number of radiation-emitting devices can be obtained. This possibility offers a cost-effective implementation of the process described here.

[0022] According to at least one embodiment, the partially cured matrix material is applied to the surface by a method selected from spraying, doctor blade application, film casting, screen or stencil printing, slot die coating and pad printing.

[0023] According to at least one embodiment, the surface is structured before the application of the partially cured matrix material. The method can therefore be used to produce planar or structured conversion elements. In particular, structuring via a lithography process is conceivable, since the partially cured matrix material can be readily applied to or into structures created by lithography and is also stable against subsequent removal of the structure, for example, a photoresist.

[0024] According to at least one embodiment, the structuring process comprises applying, selectively exposing, and developing a photoresist. The application is carried out such that the photoresist has a desired thickness, for example, 30 µm. Furthermore, the photoresist is applied to the auxiliary substrate or to the substrate on which the semiconductor chip and, if applicable, contacts are already present. The exposure is structured so that areas are created in which the developed photoresist remains, and areas that are free of photoresist after development. The photoresist-free areas are, in particular, the radiation emission surfaces or, if the photoresist is applied to an auxiliary substrate, areas whose size corresponds to the size of the radiation emission surfaces. According to at least one embodiment, the photoresist is selected from dry and wet photoresists. The photoresist can be in the form of a film.The photoresist used is, for example, a wet-film or dry-film photoresist. When selecting the photoresist, it is important to ensure that it is mechanically and thermally stable enough for the subsequent densification of the partially cured matrix material. In other words, the structuring process can be lithographic. The partially cured matrix material used here is well-suited for such structuring because it is inert to the photoresist and is not attacked or removed by a solvent, especially a paint stripper or a peeling bath, which is used to remove the photoresist in a later step. Furthermore, the partially cured matrix material, due to its plastic deformability, is well-suited for being introduced into the structures or cavities defined by the photoresist.

[0025] According to at least one embodiment, the partially cured matrix material is applied in a thickness greater than the thickness of the photoresist. In this context, "thickness" refers to its spatial extent perpendicular to the principal plane of extension of the semiconductor chip onto which the partially cured matrix material is applied. If the partially cured matrix material has a greater thickness than the previously applied photoresist, it protrudes beyond the surface of the photoresist facing away from the surface. Thus, the partially cured matrix material is present in the cavities formed by the photoresist and extends beyond it; in particular, it completely covers the photoresist.This ensures that sufficient partially cured matrix material is present in the cavities formed by the photoresist so that, after the compaction step, all cavities are completely and pore-free filled with the compact layer. For example, the cavities are between 10 µm and 120 µm high, or between 25 µm and 100 µm high, preferably between 30 µm and 60 µm high. The thickness of the conversion layer before compaction can be a multiple of the cavity height, in particular up to five times, for example up to three times. It is also possible for the fill level to be less than 1, for example 0.5.

[0026] According to at least one embodiment, the photoresist is removed before complete curing. In particular, the photoresist is removed after densification. This can be done, for example, using a solvent, especially a paint stripper or a peeling bath, which has no dissolving or aggressive effect on the partially cured matrix material in the densified compact layer. Removal with a solvent can be carried out for a period of a few minutes at room temperature.

[0027] According to at least one embodiment, the partially cured matrix material or the compact layer formed from it is ground before the photoresist is removed, so that any excess material above the photoresist is eliminated. Furthermore, the compact layer can be ground down, i.e., its thickness reduced, to achieve the desired thickness of the subsequent conversion element. This thickness can be less than the thickness of the photoresist. This completely exposes the photoresist, allowing for particularly easy removal in a subsequent step. The photoresist is removed, in particular, by a stripping solution specifically formulated for the photoresist. The stripping solution may contain N-methyl-2-pyrrolidone (NMP) or be free of it.

[0028] According to at least one embodiment, the partially cured matrix material is dissolved in a solvent and applied to the surface. Together with the phosphor particles present in the partially cured matrix material, the dissolved material forms a paste that is easy to apply. Suitable solvents can be selected from butyl acetate, 1-methoxy-2-propyl acetate (PGMEA), and acetone. Acetone, for example, is characterized by its high volatility. This solvent can dissolve the partially cured matrix material and ensures a certain processing time, meaning it does not dry too quickly. A homogeneous distribution of the phosphor particles in the partially cured matrix material is thus also guaranteed.

[0029] According to at least one embodiment, the solvent in which the partially cured matrix material is dissolved is removed by drying before compaction. According to at least one embodiment, drying is carried out at a temperature in the range of 50 °C to 1450 °C, particularly in the range of 50 °C to 150 °C, for example, in the range of 80 °C to 100 °C. According to at least another embodiment, drying is carried out for a period of 20 to 120 minutes, for example, 60 minutes.

[0030] According to at least one embodiment, compaction is achieved through plastic deformation, for example, pressing. Pressure is applied to the partially cured matrix material while simultaneously increasing the temperature. This method is well suited to removing voids and pores from the partially cured matrix material and producing a compact layer. In this compact layer, the phosphor particles are well enclosed by the partially cured matrix material. Complete curing of the partially cured matrix material does not yet occur in this step.

[0031] According to at least one embodiment, the plastic deformation, in particular the pressing, is carried out at a temperature ranging from room temperature, i.e., 20 °C to 25 °C, up to 250 °C, and at a pressure ranging from 10 MPa to 100 MPa, in particular from 32 MPa to 52 MPa, for example around 40 MPa, and / or for a time ranging from 5 minutes to 10 hours, in particular from 10 minutes to 120 minutes. The pressing can be uniaxial or isostatic.

[0032] According to at least one embodiment, complete curing is carried out at a temperature in the range of 100 °C to 300 °C and / or for a period of time in the range of 15 minutes to 6 hours, in particular 2 hours to 5 hours. During this step, the partially cured matrix material polymerizes and cross-links completely, so that the final matrix material of the conversion element is formed. Since all reactions within the matrix material that could lead to a change in volume, in particular to volume shrinkage, have already occurred during partial curing, complete curing does not result in any significant change in volume. Such volume-changing reactions include, for example, condensation reactions. According to at least one embodiment, the partially cured matrix material does not undergo any condensation reactions during complete curing.

[0033] During complete hardening, the surface of the resulting conversion element can be slightly melted and then resealed. This leads to a particularly smooth, pore- and crack-free surface of the conversion element, and potentially to rounded edges. Such microscopic flow, which can occur during complete hardening, does not alter the shape or contour of the conversion element. Any previously created structure is thus retained. On the other hand, machining marks, such as grinding marks, are removed by the microscopic flow. The resulting smooth surface of the conversion element ensures a homogeneous color distribution and thus higher color yields within the conversion element, while also preventing optical losses, for example, due to material penetrating cracks.Furthermore, such a conversion element can be easily machined, for example by sawing or grinding, and provides a good base for any further coatings or potting materials. With a conversion element manufactured in this way, pullouts caused by phosphor or other particles do not occur.

[0034] According to at least one embodiment, the partially cured matrix material is plastically deformable. This allows it to be readily applied to the surface, whether the radiation emission surface or an auxiliary substrate, with or without a structure formed by a photoresist. Both flat and structured applications can be achieved with the plastically deformable, partially cured matrix material. In particular, the partially cured matrix material has a wax-like consistency.

[0035] According to at least one embodiment, the partially cured matrix material contains phenyl groups with a proportion of up to 100 mol%. For example, the proportion of phenyl groups can range from 10 mol% to 100 mol%, and particularly from more than 30 mol%. Matrix materials with a high refractive index (HRI) in particular have a high proportion of phenyl groups. Partially cured HRI matrix materials can reduce optical losses in the conversion element, thus leading to increased brightness in the finished device. Such a device then exhibits high efficiency and light yield. In general, a higher phenyl content in the partially cured matrix material results in lower B-stage character or B-stage character at higher temperatures. B-stage character refers in particular to plastic deformability and the ability to undergo further crosslinking.

[0036] According to at least one embodiment, the partially hardened matrix material is a pre-crosslinked polysiloxane.

[0037] According to at least one embodiment, the partially cured matrix material is a high-refractive-index matrix material (HRI matrix material). However, the partially cured matrix material can also be selected from low-refractive-index matrix materials (LRI). The refractive index is in the range of 1.51 to 1.59, particularly in the range of 1.53 to 1.55. Advantageously, the partially cured matrix material and / or the matrix material thus exhibits a higher refractive index compared to other polysiloxanes or silicones.

[0038] According to at least one embodiment, the partially cured matrix material is free of filler material. Filler material can be easily omitted because the processing of the partially cured matrix material is not very complex.

[0039] According to at least one embodiment, the partially hardened matrix material includes a filler material.

[0040] According to at least one embodiment, the method produces a conversion element with a thickness between 10 µm and 100 µm inclusive, in particular between 10 µm and 90 µm inclusive, for example between 10 µm and 60 µm inclusive. For example, the thickness is 30 µm. According to at least another embodiment, the proportion of phosphor particles in the conversion element is between 10 vol% and 60 vol%, in particular between 30 vol% and 50 vol%. This allows the production of components with conversion elements that are thin and / or highly filled with phosphor particles. Such conversion elements exhibit good thermal performance and high luminous efficacy.

[0041] A radiation-emitting component is further specified. This radiation-emitting component can be manufactured, in particular, using the method described herein. All characteristics mentioned in connection with the method therefore also apply to the component, and vice versa.

[0042] According to at least one embodiment, the radiation-emitting component comprises a semiconductor chip which, in operation, emits electromagnetic radiation of a first wavelength range from a radiation emission surface (11), and a conversion element comprising a matrix material in which phosphor particles are embedded which convert electromagnetic radiation of the first wavelength range into electromagnetic radiation of a second wavelength range, wherein the conversion element is fixed without adhesive on the radiation emission surface and has a crack- and gap-free surface.

[0043] An adhesive-free fixation of the conversion element to the radiation emission surface means that the conversion element is positioned directly on the semiconductor chip or its radiation emission surface. The semiconductor chip and the conversion element share a common interface; in particular, there is no thermal barrier between them, such as an adhesive layer. This allows for particularly efficient heat dissipation from the conversion element, which has a positive effect on the device's performance. The absence of an adhesive layer is not only thermally but also optically advantageous for the device, as it avoids optical losses caused by incorrectly applied adhesive.

[0044] The crack- and crevice-free surface is a particularly smooth surface, which leads to a homogeneous color distribution and thus to a high light output.

[0045] According to at least one embodiment, the radiation-emitting component is manufactured using a method described here. This allows for particularly simple, time-saving, and cost-effective production.

[0046] According to at least one embodiment, the matrix material is a polysiloxane, for example a polysiloxane produced from pre-crosslinked polysiloxane.

[0047] According to at least one embodiment, the matrix material contains up to 100% phenyl groups. This can be, in particular, a high refractive index (HRI) matrix material, which exhibits low optical losses and ensures high efficiency and light transmission of the component. A high proportion of phenyl groups also results in a lower proportion of other organic groups in the matrix material, especially fewer organic groups than in silicone. Therefore, the matrix material described here exhibits better heat resistance than silicone.

[0048] According to at least one embodiment, the conversion element is free of filler materials. This results in particularly low optical losses. However, it is also possible for filler materials to be embedded in the conversion element.

[0049] According to at least one embodiment, the conversion element has rounded edges. These can be generated, for example, by the complete curing of the partially cured matrix material as described here. The rounded edges can offer advantages in terms of composite construction, for example, in subsequent encapsulation with silicone. For instance, the rounded edges reduce the risk of stress concentrations at the corners that could develop into cracks.

[0050] Further advantageous embodiments and developments of the component and the method result from the exemplary embodiments described below in conjunction with the figures. Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6 to Fig. Figure 7 shows schematic cross-sectional views of process steps for the production of radiation-emitting components. Fig. Figure 8 shows a schematic cross-sectional view of radiation-emitting components. Fig. Figure 9 shows a microscopic image of top views of compact layers.

[0051] In the exemplary embodiments and figures, identical, similar, or equivalent elements may be designated with the same reference numerals. The depicted elements and their relative sizes are not to be considered to scale; rather, individual elements, such as layers, components, building elements, and areas, may be exaggerated for clarity and / or better understanding.

[0052] Fig. Figure 1 shows a schematic cross-sectional view of a substrate 15 on which, by way of example, two semiconductor chips 10 and each associated top contact 12 are arranged. The substrate 15 could also be arranged with only a single semiconductor chip 10 or with a plurality of semiconductor chips 10. In general, the embodiment described below for a method for manufacturing a radiation-emitting component works with both a single semiconductor chip 10 and a plurality of semiconductor chips 10 simultaneously, which makes the method particularly cost-effective.

[0053] In this example, the substrate 15 is a silicon wafer. The semiconductor chips 10 are surface-emitting, meaning they have the radiation emission surface 11 on their side facing away from the substrate 15.

[0054] To create a structure, a photoresist 30, in this example a negative dry-film photoresist based on acrylate, is applied to the substrate 15 with the semiconductor chips 10 and contacts 12 arranged on it. The photoresist 30 has a thickness of 30 µm in this example. The photoresist 30 is exposed except in the areas above the radiation emission surfaces 11. After development of the photoresist 30, cavities form in the photoresist 30 above the radiation emission surfaces 11, as shown in Fig. 2 shown.

[0055] In a further step, a partially cured matrix material 21 is provided, which contains embedded phosphor particles and a solvent. The phosphor particles, for example, have one or more garnet phosphors. Butyl acetate was used as the solvent. The matrix material 21 is, in particular, a pre-crosslinked HRI siloxane with a phenyl content in the range of 40 mol% to 70 mol%. The partially cured matrix material 21 is thus in solution, so that it has the consistency of a paste. The homogenized partially cured matrix material 21 is applied to the substrate 15, which is structured with the photoresist 30, using a spatula, so that the radiation emission surfaces 11 in the cavities are completely covered. As in Fig. As shown in Figure 3, the layer of partially cured matrix material 21 has a protrusion over the photoresist 30, so that the latter is also covered by the partially cured matrix material. This is important to ensure that enough material is present to guarantee that the cavities are completely and pore-free filled after the subsequent compaction step.

[0056] After application with a doctor blade, the partially cured matrix material 21 is dried, thereby completely or largely removing the solvent. In this example, drying takes place for 1 hour at 100 °C. Fig. Figure 4 shows, in an enlarged view, the partially cured matrix material 21 after drying in a cavity formed by the photoresist 30 above the radiation emission surface 11. It is clearly visible that pores and cavities are present within the partially cured matrix material 21, and that cavities free of partially cured matrix material 21 are also present between the partially cured matrix material 21 and the adjacent surfaces of the semiconductor chip 10 and the photoresist 30.

[0057] To eliminate these pores and voids and thus achieve complete coverage of the radiation emission surface 11 with the partially cured matrix material 21, a compaction step follows. Compaction is carried out by pressing, in particular isostatic pressing, at a temperature above 50 °C. The temperature is, for example, in the range of 60 °C to 90 °C, and the pressure is, for example, in the range of 40 MPa to 60 MPa. Fig. Figure 5 shows the compact layer 22, which contains the partially cured matrix material 21, now free of pores and cavities. It is also evident that the compact layer 22 shares a common interface with the radiation emission surface 11 across its entire area. Within the compact layer 22, the phosphor particles are well and completely enclosed by the partially cured matrix material 21 due to the compaction process.

[0058] In a further step, the compact layer can be mechanically processed. In this example, on a wafer grinding machine, the excess compact layer 22 is first ground away from above, and then the compact layers 22, now separated by the photoresist 30, are brought to the desired thickness for the subsequent conversion element 20, as shown in Fig. 6 shown. The desired thickness can, for example, be a few µm below that of the side of the photoresist 30 facing away from the substrate 15, so that it is reliably exposed.

[0059] In a further step, as in Fig. Figure 7 shows the removal of the photoresist. This is done using a suitable solvent, the so-called stripping medium, for example, at room temperature for a few minutes. The stripping medium is, for example, free of NMP and / or contains tetramethylammonium hydroxide (TMAH). The compact layers 22 are not attacked or dissolved during this process. Subsequently, the compact layers 22 are fully cured, thus forming the conversion elements 20. During full curing, the already partially cured matrix material 21 softens only slightly and flows, particularly on the outer surfaces. This preserves the contour of the compact layer 22 and seals the surface of the conversion element without cracks or gaps. Full curing takes place, for example, at temperatures between 100 °C and 280 °C. For example, full curing is carried out for 4 hours at 250 °C.Since the partially hardened matrix material 21 shows no or hardly any volume shrinkage during complete hardening, a conversion element 20 with a particularly crack- and gap-free surface is formed.

[0060] The manufactured components arranged on the substrate 15 are separated from each other, thus yielding, in this example, two radiation-emitting components 100 ( Fig. 8).

[0061] In alternative embodiments, the partially cured matrix material 21 is applied to the substrate over a flat surface, i.e. without a previously applied photoresist 30.

[0062] In another alternative embodiment, the partially cured matrix material 21 is applied to an auxiliary substrate, where it is dried and compacted. In this alternative, the compact layer 22 formed on the auxiliary substrate can be characterized before being placed on the radiation emission surface 11 and, if necessary, reworked or discarded. This avoids the costly discarding of a composite of semiconductor chip 10 and conversion element 20.

[0063] Fig.Figure 9 shows microscopic images (magnification 100x) of a top view of semiconductor chips 10 coated with a partially cured matrix material 21, which has already been compacted into a compact layer 22. On the right side, the photoresist 30 is still present between the individual semiconductor chips 10 and the compact layers 22 arranged on them. However, the compact layers 22 have already been mechanically processed, i.e., ground to the desired thickness. This is also evident from the machining marks on the photoresist 30. On the left side, no photoresist is present between the compact layers 22 (removed photoresist 31). It can be seen that removing the photoresist 30 did not attack or partially remove the compact layers 22. This shows that the partially cured matrix material 21 is stable against the solvent used to remove the photoresist 30.

[0064] The features and embodiments described in connection with the figures can be combined with one another according to further embodiments, even if not all combinations are explicitly described. Furthermore, the embodiments described in connection with the figures can alternatively or additionally include further features as described in the general section.

[0065] The invention is not limited to the description provided by means of the exemplary embodiments. Rather, the invention encompasses every new feature as well as every combination of features, which in particular includes every combination of features in the claims, even if that feature or combination itself is not explicitly stated in the claims or exemplary embodiments. Reference symbol list 10 Semiconductor chips 11 Radiation emission surface 12 Contacting 15 substrate 20 Conversion element 21 Partially hardened matrix material 22 Compact layer 30 photoresist 31 Removed photoresist

Claims

[1] Method for manufacturing a radiation-emitting device (100) comprising the process steps: - Providing at least one semiconductor chip (10) which, during operation, emits electromagnetic radiation of a first wavelength range from a radiation emission surface (11), - Manufacturing a conversion element (20) on the radiation emission surface (11), wherein manufacturing the conversion element (20) comprises the process steps: - Applying a partially cured matrix material (21) in which phosphor particles are embedded that convert electromagnetic radiation of the first wavelength range into electromagnetic radiation of a second wavelength range, to a surface, - Compacting the partially hardened matrix material (21) to produce a compact layer (22), - Complete hardening of the compact layer (22), wherein the surface is the radiation emission surface (11) of the semiconductor chip (10) or an auxiliary substrate from which the compact layer (22) is transferred to the radiation emission surface (11) prior to complete hardening. [2] Method according to the preceding claim, wherein a plurality of semiconductor chips (10) are provided on a common substrate (15), which are separated after complete hardening. [3] Method according to one of the preceding claims, wherein the surface is structured before the application of the partially cured matrix material (21). [4] Method according to the preceding claim, wherein the structuring comprises applying, selectively exposing and developing a photoresist (30). [5] Method according to the preceding claim, wherein the partially cured matrix material (21) is applied in a thickness greater than the thickness of the photoresist (30). [6] Method according to one of the preceding claims 4 or 5, wherein the photoresist (30) is removed before complete hardening. [7] Method according to one of the preceding claims, wherein the partially cured matrix material (21) is applied dissolved in a solvent. [8] Method according to the preceding claim, wherein the solvent is removed by drying before compaction. [9] Method according to the preceding claim, wherein the drying is carried out at a temperature in the range of 50 °C to 1450 °C and / or for a period of 20 min to 120 min. [10] Method according to one of the preceding claims, wherein the compaction is carried out by plastic deformation, in particular uniaxial or isostatic pressing. [11] Method according to the preceding claim, wherein the plastic deformation is carried out at a temperature from the range of room temperature to 250 °C and at a pressure from the range of 10 MPa to 100 MPa and / or for a period of time from the range of 5 min to 10 h. [12] Method according to any of the preceding claims, wherein the complete hardening is carried out at a temperature in the range of 100 °C to 300 °C and / or for a period of time in the range of 15 min to 6 h. [13] Method according to any of the preceding claims, wherein the partially cured matrix material (21) does not undergo any condensation reactions during complete curing. [14] Method according to any of the preceding claims, wherein the partially hardened matrix material (21) is plastically deformable. [15] Method according to any of the preceding claims, wherein the partially hardened matrix material (21) contains phenyl groups with a proportion of up to 100%. [16] comprising a radiation-emitting component (100) - a semiconductor chip (10) which, during operation, emits electromagnetic radiation of a first wavelength range from a radiation emission surface (11), and - comprising a conversion element (20) comprising a matrix material in which phosphor particles are embedded which convert electromagnetic radiation of the first wavelength range into electromagnetic radiation of a second wavelength range, wherein the conversion element (20) is fixed without adhesive on the radiation emission surface (11) and has a crack- and gap-free surface. [17] Radiation-emitting component (100) according to the preceding claim, which is manufactured by a method according to any one of claims 1 to 15. [18] Radiation-emitting device (100) according to one of claims 16 or 17, wherein the matrix material comprises phenyl groups with a proportion of up to 100%. [19] Radiation-emitting component (100) according to one of claims 16 to 18, wherein the conversion element (20) is free of filler materials. [20] Radiation-emitting component (100) according to any one of claims 15 to 19, wherein the conversion element (20) has rounded edges.

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