DE102012104274A1 - Method for producing a ceramic conversion element, ceramic conversion element and optoelectronic semiconductor component - Google Patents

Abstract

A method for producing a ceramic conversion element (3) comprises the following steps: providing a first layer (1) as a green body or as a ceramic layer which has a first phosphor which converts electromagnetic radiation of a first wavelength range into electromagnetic radiation of a second wavelength range, wherein the first phosphor, - applying a second layer (2) on the first layer (1), wherein the second layer (2) comprises a second phosphor which converts electromagnetic radiation of a first wavelength range into electromagnetic radiation of a third wavelength range. Furthermore, a ceramic conversion element and an optoelectronic semiconductor component are specified.

Description

A method for producing a ceramic conversion element, a ceramic conversion element and an optoelectronic semiconductor component are specified.

A ceramic conversion element is for example in the document DE 10 2011 010 118.7 described. The conversion element according to this document comprises two different ceramic layers, of which only one ceramic layer is formed wavelength-converting, while the other ceramic layer is a carrier layer. However, such a conversion element is usually not suitable to produce warm white light together with a light source emitting blue light, since two different phosphors usually have to be used to produce warm white light.

An object of the present invention is to provide a ceramic conversion element comprising two different phosphors. Furthermore, a method for producing such a conversion element is to be specified and an optoelectronic semiconductor component with such a conversion element.

These objects are achieved by a method having the steps of claim 1, by a ceramic conversion element having the features of claim 10 and by an optoelectronic semiconductor device having the features of claim 14.

Further advantageous embodiments and further developments of the method, the ceramic conversion element and the optoelectronic semiconductor component are specified in the respective dependent claims.

• – Bereitstellen einer ersten Schicht als Grünkörper oder als keramische Schicht, wobei der Grünkörper oder die keramische Schicht einen ersten Leuchtstoff aufweist, der elektromagnetische Strahlung eines ersten Wellenlängenbereichs in elektromagnetische Strahlung eines zweiten Wellenlängenbereichs umwandelt, und
• – Aufbringen einer zweiten Schicht auf die erste Schicht, wobei die zweite Schicht einen zweiten Leuchtstoff aufweist, der elektromagnetische Strahlung eines ersten Wellenlängenbereichs in elektromagnetische Strahlung eines dritten Wellenlängenbereichs umwandelt.

A method for producing a ceramic conversion element comprises in particular the following steps:

• Providing a first layer as a green body or as a ceramic layer, wherein the green body or the ceramic layer comprises a first phosphor which converts electromagnetic radiation of a first wavelength range into electromagnetic radiation of a second wavelength range, and
• - Applying a second layer to the first layer, wherein the second layer comprises a second phosphor which converts electromagnetic radiation of a first wavelength range into electromagnetic radiation of a third wavelength range.

The green body may, for example, be a composite of a plurality of green sheets laminated on one another. Furthermore, a green body in the present case is understood as meaning a single green sheet.

Particularly preferably, the first wavelength range, the second wavelength range and the third wavelength range are each formed differently from one another. This does not necessarily mean that the first wavelength range, the second wavelength range and the third wavelength range are distinct from each other. Rather, the wavelength ranges may differ, but overlap in subregions.

Particularly preferably, the first phosphor is based on at least one oxygen-containing inorganic compound and the second phosphor on a nitride or an oxynitride.

For example, it is also possible that the first phosphor and the second phosphor are each based on at least one oxygen-containing inorganic compound. In this case, however, the first phosphor and the second phosphor are generally quite different from each other in terms of their chemical composition in order to be able to convert radiation of the first wavelength range into two wavelength ranges which are different from one another.

Likewise, however, it is also possible for the first phosphor and the second phosphor to each be based on a nitride or an oxynitride. However, in this embodiment as well, the first phosphor and the second phosphor are generally quite different from one another in terms of their chemical composition in order to be able to convert radiation of the first wavelength range into two wavelength ranges which are different from one another.

Particularly preferably, the first layer is substantially free of the second phosphor. The second layer is particularly preferably substantially free of the first phosphor. Preferably, the content of the first phosphor in the second layer and / or the content of the second phosphor in the first layer do not exceed 5%.

Particularly preferably, the content of the first phosphor in the second layer and / or the content of the second phosphor in the first layer do not exceed 0.1%. Such a low phosphor content of the first phosphor in the second layer and / or the second phosphor in the first layer may arise, for example, due to diffusion processes or manufacturing tolerances.

A central idea of the present ceramic conversion element is to arrange the two different phosphors, which are necessary to convert primary light of the first wavelength range into two different wavelength ranges, into mutually different layers in order to minimize the contact area between the two different phosphors. In this way, the degradation of the phosphors, for example, due to chemical reactions with one another, can be at least reduced during production. In particular, in the sintering of the layers to produce a ceramic chemical reactions are otherwise often difficult to prevent due to the necessary for sintering high temperatures.

The problem of chemical reactions between different phosphors arises in particular in the use of an oxide phosphor based on oxygen-containing inorganic compounds, together with a nitrogen-based, nitridic or oxinitridischen phosphor, since these due to the oxygen content in the one phosphor and the nitrogen content in the other phosphor easily chemically react with each other. Especially for the production of warm white light from blue primary radiation, oxygen-containing inorganic compounds based, oxidic phosphors in combination with nitridic / oxinitridische phosphors are particularly suitable. The oxidic phosphors based on oxygen-containing inorganic compounds usually produce the yellowish to greenish portion of the warm white light and the nitridic / oxinitridic phosphors the orange to red portion of the warm white light.

According to one embodiment of the method, the first layer and the second layer are each formed in a ceramic manner and are connected to one another in a material-bonded manner by means of a joining layer. The bonding layer has, for example, an adhesive or is formed from an adhesive.

In this embodiment of the method, the first layer is particularly preferably drawn in a first step from a base material comprising the first phosphor in a green sheet or provided as a green body, which may be formed from a plurality of green foil laminated on top of each other.

The base material usually contains organic materials, such as a binder, besides the phosphor. The green sheet or green body is then debinded and sintered to form a finished first ceramic layer suitable for converting primary radiation of the first wavelength range into radiation of the second wavelength range.

The second ceramic layer is also drawn in this embodiment of the method from a base material having the second phosphor in a green sheet or provided as a green body. The green body or the green sheet are debinded and sintered, so that a finished second ceramic layer is formed. The second ceramic layer is suitable because of the contained second phosphor to convert radiation of the first wavelength range into radiation of the third wavelength range.

Subsequently, the two finished ceramic layers are firmly bonded, for example with an adhesive layer. Particularly preferably, the joining layer is made comparatively thin. Preferably, the thickness of the bonding layer does not exceed 10 μm.

In this embodiment of the method, the two ceramic layers are produced in particular in separate sintering steps. This has the advantage that the sintering conditions can be matched to the particular phosphor of the layer. Furthermore, the first phosphor and the second phosphor are not sintered together in this embodiment, so that a degradation of at least one of the two phosphors due to chemical reactions among each other, which can take place especially at high temperatures for sintering, at least reduced.

According to another embodiment of the method, the second layer is provided as a green sheet or as a green body and laminated onto the first layer. This layer composite comprising the first and the second layer is then sintered. As a rule, the layer composite is debinded before sintering.

In this embodiment of the method, the first layer can also be provided, for example, in the form of a green sheet or a green body, wherein the first layer and the second layer are then sintered together.

Alternatively, the first layer is provided as a finished ceramic layer onto which the second layer is laminated as a green sheet or as a green body. In the subsequent sintering step, only the second layer is then debinded and sintered. This has the advantage that the sintering of the first layer and the sintering of the second layer subsequently take place on each other, so that the sintering parameters can be adapted to the respective phosphor.

According to a further embodiment of the method, a base material of the second layer with the second phosphor is applied to the first layer by a coating method.

The coating process may be, for example, one of the following processes: printing - for example screen printing -, spraying, sedimentation. In a next step, the layer composite of the first layer and the second ceramic layer is in turn sintered. Also in this embodiment of the method, the first layer can be present either as a finished ceramic layer or as a green body.

The base material comprises the respective phosphor. Furthermore, the base material usually contains additional substances, which are usually matched to the respective coating method.

A base material for a printing process, such as screen printing, usually comprises a binder in addition to the respective phosphor. It is also possible that the base material for the printing process additionally contains a solvent.

A base material for a sedimentation process is usually in the form of a suspension. The base material for a sedimentation process therefore usually comprises, in addition to the respective phosphor, a solvent, for example an alcohol or water.

The base material for a spraying process comprises, for example, a binder and / or a solvent in addition to the respective phosphor.

According to a further embodiment of the method, a ceramic intermediate layer is arranged between the first layer and the second layer.

The application of the ceramic intermediate layer to the first layer can basically be carried out analogously to the application of the second layer to the first layer. Therefore, only a few embodiments for applying the ceramic intermediate layer will be described below. However, it will be apparent to those skilled in the art in light of the present specification that additional embodiments for applying the intermediate layer to the first layer will result.

The ceramic intermediate layer can be laminated, for example, as a green film in the layer composite of a green body for the first layer and a green body for the second layer between them. Subsequently, the layer composite is sintered, so that a ceramic conversion element is formed.

Furthermore, it is also possible, for example, for a base material of the ceramic intermediate layer to be applied to the first layer, which is present for example as a finished ceramic, by means of a coating method. As a rule, the base material of the ceramic intermediate layer is sintered before the production of the second layer. Subsequently, the second layer is applied to the intermediate layer with one of the steps described herein. The second layer can be applied for example in the form of a green sheet or a green body on the intermediate layer or glued as a finished ceramic.

Furthermore, it is also possible that the first layer is provided as a finished ceramic layer onto which a green film for the intermediate layer and a green film for the second layer are laminated. The green sheet for the intermediate layer can in this case be sintered before the application of the green sheet for the second layer. Alternatively, it is also possible to sinter the green film for the intermediate layer and the green film for the second layer in a common step to a ceramic.

In one embodiment, the intermediate ceramic layer reduces at least the contact between the first layer and the second layer. Furthermore, the ceramic intermediate layer may additionally or alternatively serve as a diffusion barrier between the first layer and the second layer. In other words, the intermediate ceramic layer may be formed to at least reduce the diffusion between the first layer and the second layer.

Furthermore, the ceramic intermediate layer may additionally or alternatively also at least reduce possible chemical reactions between the first layer and the second layer. Such a ceramic intermediate layer can thus have the task of preventing a material exchange between the first layer and the second layer and consequently helping to further avoid a degradation of the phosphors.

Finally, the ceramic intermediate layer can additionally or alternatively be designed such that it serves for the adhesion mediation between the first layer and the second layer.

The ceramic intermediate layer preferably has a thickness of between 0.5 μm and 100 μm inclusive. The ceramic intermediate layer particularly preferably has a thickness of between 5 μm and 20 μm inclusive.

The ceramic intermediate layer particularly preferably comprises one of the following materials or is formed from one of the following materials: aluminum oxide, aluminum nitride, silicon nitride, silicon dioxide, yttrium oxide.

The first phosphor is more preferably selected from the group consisting of rare-earth-doped garnets, rare-earth-doped aluminates, rare-earth-doped silicates such as orthosilicates or chlorosilicates. The phosphors mentioned can be doped in addition to a doping with a rare earth, for example, with manganese.

For example, the first phosphor may be a YAG phosphor, for example YAG: Ce. In particular, the first phosphor is particularly preferably suitable for converting blue light of the first wavelength range into yellow to green light of the second wavelength range.

More preferably, the second phosphor is selected from the group consisting of rare earth doped alkaline earth silicon nitrides, rare earth doped alkaline earth metal aluminum nitrides.

If the second phosphor is an oxinitridic phosphor, it is, for example, a rare-earth-doped alkaline-earth ionone.

In particular, the second phosphor is particularly preferably suitable for converting blue light of the first wavelength range into orange to red light of the third wavelength range.

• – eine erste keramische Schicht, die einen ersten Leuchtstoff aufweist, der elektromagnetische Strahlung eines ersten Wellenlängenbereichs in elektromagnetische Strahlung eines zweiten Wellenlängenbereichs umwandelt, und
• – eine zweite keramische Schicht, die einen zweiten Leuchtstoff aufweist, der elektromagnetische Strahlung eines ersten Wellenlängenbereichs in elektromagnetische Strahlung eines dritten Wellenlängenbereichs umwandelt.

A ceramic conversion element, which can be produced, for example, by one of the methods described above, comprises in particular:

• A first ceramic layer comprising a first phosphor which converts electromagnetic radiation of a first wavelength range into electromagnetic radiation of a second wavelength range, and
• A second ceramic layer comprising a second phosphor which converts electromagnetic radiation of a first wavelength range into electromagnetic radiation of a third wavelength range.

According to an embodiment of the ceramic conversion element, the main extension planes of the first ceramic layer and the second ceramic layer are arranged parallel to a main surface of the ceramic conversion element.

The first ceramic layer preferably has a thickness of between 50 μm and 500 μm inclusive. Particularly preferably, the first ceramic layer has a thickness of between 80 μm and 120 μm inclusive.

The second ceramic layer preferably has a thickness of between 2 μm and 200 μm inclusive. Particularly preferably, the second ceramic layer has a thickness of between 10 μm and 50 μm inclusive.

According to a further embodiment of the ceramic conversion element, this comprises a support on which the first ceramic layer and the second ceramic layer are arranged. The carrier is preferably provided to mechanically stabilize the ceramic conversion element. Particularly preferably, the carrier is free of wavelength-converting properties. Particularly preferably, the carrier is furthermore permeable to visible light and in particular to electromagnetic radiation of the first, the second and the third wavelength range. For example, the carrier is formed of a ceramic.

The ceramic conversion element is not limited to two different layers, each with two different phosphors. Rather, it is possible that the ceramic conversion element has more than two different layers with different phosphors. These different layers can be separated from one another by ceramic intermediate layers, for example. By means of several different layers, which have different phosphors, it is possible in particular, together with a primary light source, to achieve light of arbitrary color locations.

• – einen Halbleiterkörper, der im Betrieb elektromagnetische Strahlung aus einem ersten Wellenlängenbereich aussendet, und
• – ein keramisches Konversionselement, wie es beispielsweise oben beschrieben wurde.

An optoelectronic semiconductor component comprises in particular:

• A semiconductor body emitting electromagnetic radiation from a first wavelength range during operation, and
• - A ceramic conversion element, as described above, for example.

The ceramic conversion element is in particular suitable for converting electromagnetic radiation from the first wavelength range at least partially into radiation from the second wavelength range and the third wavelength range, so that the optoelectronic semiconductor component emits electromagnetic radiation of the first wavelength range, of the second wavelength range and of the third wavelength range.

The ceramic conversion element is in this case preferably arranged with its main surface parallel to the radiation exit surface of the semiconductor body. Particularly preferably, the ceramic conversion element is arranged in direct contact with the semiconductor body. As a result, advantageously, heat which arises during operation can be well dissipated by the conversion element via the semiconductor body.

According to a preferred embodiment of the optoelectronic semiconductor component, the first wavelength range comprises blue light, the second wavelength range yellow to green light and the third wavelength range orange to red light. In this embodiment, the optoelectronic semiconductor component particularly preferably emits mixed-colored radiation having a color locus in the warm-white region of the CIE standard color chart.

It goes without saying that embodiments which are described here only in conjunction with the conversion element can also be used in conjunction with the optoelectronic semiconductor component and the method. Furthermore, embodiments that are described only in connection with the method can find use in the conversion element as well as in the semiconductor device. Also, embodiments described only in connection with the semiconductor device may be formed in the method and the conversion element.

Further advantageous embodiments and developments of the invention will become apparent from the embodiments described below in conjunction with the figures.

Based on the schematic sectional views of 1 to 3 a first embodiment of a method for producing a ceramic conversion element will be described.

Based on the schematic sectional views of 4 to 6 another embodiment of a method for producing a ceramic conversion element will be described.

Based on the schematic sectional views of 7 and 8th a further embodiment for producing a ceramic conversion element will be described.

The 9 and 10 each show a schematic sectional view of an embodiment of a ceramic conversion element.

11 shows a schematic sectional view of an optoelectronic semiconductor device according to an embodiment.

Based on the schematic sectional views of 12 to 16 a further embodiment for producing a ceramic conversion element will be described.

The same, similar or equivalent elements are provided in the figures with the same reference numerals. The figures and the proportions of the elements shown in the figures with each other are not to be considered to scale. On the contrary, individual elements, in particular layer thicknesses, can be exaggerated for better representability and / or better understanding.

In the method according to the embodiment of the 1 to 3 becomes in a first step a first layer 1 comprising a first phosphor which converts electromagnetic radiation of a first wavelength range into electromagnetic radiation of a second wavelength range. In this case, the first phosphor is based on at least one oxygen-containing inorganic compound. For example, the first phosphor is a garnet phosphor, such as YAG: Ce.

The provided first layer 1 is already formed ceramic in the present embodiment.

In a second step, which is schematically in 2 is shown on the first layer 1 a second layer 2 applied, wherein the second layer 2 a second phosphor which converts electromagnetic radiation of a first wavelength range into electromagnetic radiation of a third wavelength range. The second layer 2 is presently designed as a green sheet or as a green body, which on the first layer 1 is laminated. Alternatively, it is also possible to provide a base material of the second layer comprising the second phosphor by a coating method on the first layer 1 applied. The coating process may be, for example, printing - such as screen printing -, spraying or sedimentation.

As the second phosphor in the present case, a nitridic or oxinitridischer phosphor is used.

In a next step, which is schematically in 3 is shown, the entire composite layer, comprising the first layer 1 and the green body or the green sheet of the second layer 2 , debinded and sintered. In the debinding step First, the organic binder from the green body or the green sheet of the second layer 2 away. In the sintering step, the material of the green sheet transforms into the second ceramic layer 2 around. The finished ceramic conversion element 3 that is schematically in 3 is now generally formed entirely of ceramic material and more preferably free of an organic material.

Particularly preferred is the first ceramic layer 1 the ceramic conversion element 3 adapted to at least partially convert blue light of a first wavelength range into yellow to green light of a second wavelength range. The second ceramic layer 2 the ceramic conversion element 3 is particularly preferably suitable for converting blue light of a first wavelength range at least partially into orange to red light of a third wavelength range.

Furthermore, in the present ceramic conversion element 3 the main extension planes of the first ceramic layer 1 and the second ceramic layer 2 each parallel to a main surface of the ceramic conversion element 3 arranged.

In the method according to the embodiment of the 4 to 6 becomes a first layer 1 provided in the form of a green body having a first phosphor. Also the second layer 2 is provided in this embodiment in the form of a green sheet comprising a second phosphor ( 4 ).

In a further step, which is schematically in 5 is shown, the first layer 1 and the second layer 2 laminated together.

Furthermore, it is alternatively possible, only the first layer 1 in the form of a green body and a base material of the second layer 2 by means of a coating process on the first layer 1 applied.

In a further step, the first layer 1 and the second layer 2 or the base material of the second layer 2 sintered together, so that a ceramic conversion element 3 arises, which is schematically in 6 is shown. The first ceramic layer 1 and the second ceramic layer 2 , which originated during the sintering process, are in direct contact with each other.

In the method according to the embodiment of the 7 to 8th become the first layer 1 and the second layer 2 both provided as ceramic layers ( 7 ). Here, the debinding and sintering steps for the preparation of the two ceramic layers 1 . 2 previously taken separately from each other, so that in particular the sintering conditions could be adapted to the respective phosphor.

In a further step, the two ceramic layers 1 . 2 with a marriage story 4 cohesively connected to each other ( 8th ). The marriage story 4 is in the present case formed from an adhesive.

The ceramic conversion element 3 according to the embodiment of the 9 comprises, in contrast to the ceramic conversion element 3 according to the embodiment of the 6 an intermediate layer 5 that between the first layer 1 and the second layer 2 is arranged in direct contact with these.

The intermediate layer 5 is particularly preferably also ceramic. The ceramic intermediate layer 5 For example, you have one of the following materials:
Alumina, aluminum nitride, silicon nitride, silica, yttria.

The ceramic intermediate layer 5 in the present case advantageously reduces the contact between the first layer 1 and the second layer 2 and further preferably prevents diffusion of materials between the first layer 1 and the second layer 2 , Also a chemical reaction between the material of the first layer 1 and the second layer 2 can through the ceramic interlayer 5 in the present case, particularly preferably be effectively reduced.

Alternatively or additionally, the ceramic intermediate layer 5 also the adhesion between the first layer 1 and the second layer 2 improve.

The ceramic conversion element 3 according to the embodiment of the 10 comprises, in contrast to the ceramic conversion element 3 according to the 6 a carrier 6 on which the first layer 1 and the second layer 2 are arranged. The carrier 6 is intended, the ceramic conversion element 3 mechanically stabilize. The carrier 6 is in the present case free of wavelength-converting properties and transparent to visible light. Such a carrier 6 is for example in the cited document DE 10 2011 010 118.7 The disclosure of which is hereby incorporated by reference.

The optoelectronic semiconductor component according to the exemplary embodiment of FIG 11 comprises a semiconductor body 7 with an active radiation generating zone 8th , The active radiation-generating zone 8th is suitable for generating electromagnetic radiation of the first wavelength range during operation of the optoelectronic semiconductor component. The active zone 8th in this case preferably comprises a pn junction, a double heterostructure, a single quantum well or, more preferably, a multiple quantum well structure (MQW) for generating radiation.

The of the semiconductor body 7 emitted electromagnetic radiation of the first wavelength range particularly preferably comprises blue light. The blue light of the first wavelength range is in the operation of the semiconductor device of a radiation exit surface 9 of the semiconductor body 7 sent. On the radiation exit surface 9 of the semiconductor body 7 is a ceramic conversion element in the present embodiment 3 applied in direct contact. For example, the ceramic conversion element 3 on the semiconductor body 7 with an adhesive layer 10 attached. The ceramic conversion element 3 is already based on the 6 been described.

The ceramic conversion element 2 is arranged in the present embodiment, the main surface of which is parallel to the radiation exit surface 9 of the semiconductor body 7 runs.

The first ceramic layer 1 the ceramic conversion element 3 converts a part of the blue radiation of the semiconductor body 7 in yellow to green radiation around. Another part of the blue radiation of the semiconductor body 7 is from the second ceramic layer 2 the ceramic conversion element 3 in orange to red radiation, while another part of the of the semiconductor body 7 emitted blue radiation, the ceramic conversion element 3 goes through unconverted. The radiation components are in this case designed such that the optoelectronic semiconductor component emits mixed-colored radiation having a color locus from the warm-white region of the CIE standard color chart.

The following is based on the 12 to 16 an embodiment for producing a ceramic conversion element 3 with an intermediate layer 5 as described, for example 9 has been described.

In a first step, a first layer 1 provided as a finished ceramic layer ( 12 ). The first shift 1 comprises a first phosphor based on at least one oxygen-containing inorganic compound, which is suitable for converting electromagnetic radiation of a first wavelength range into electromagnetic radiation of a second wavelength range.

In a next step, the first ceramic layer is applied 1 a green sheet for a ceramic intermediate layer 5 laminated ( 13 ). Alternatively, a base material for a ceramic intermediate layer could also be used 5 by means of a coating process on the first layer 1 be applied.

In a further step, the layer composite of the first layer 1 and the green sheet for the intermediate layer 5 sintered, leaving the interlayer 5 is formed ceramic ( 14 ).

On the ceramic intermediate layer 5 Now, in a further step, a green sheet for the second layer 2 laminated ( 15 ). The green sheet contains a second nitridic or oxynitride phosphor which is suitable for converting electromagnetic radiation of the first wavelength range into electromagnetic radiation of the third wavelength range.

The layer composite comprising the first ceramic layer 1 , the ceramic intermediate layer 5 and the green sheet for the second layer 2 are now sintered, leaving the second layer 2 is also ceramic ( 16 ).

The invention is not limited by the description based on the embodiments of these. Rather, the invention encompasses any novel feature as well as any combination of features, including in particular any combination of features in the claims, even if this feature or combination itself is not explicitly stated in the patent claims or exemplary embodiments.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• DE 102011010118 [0002, 0082]

Claims (20)

Method for producing a ceramic conversion element ( 3 ) comprising the steps: - providing a first layer ( 1 ) as a green body or as a ceramic layer, which comprises a first phosphor which converts electromagnetic radiation of a first wavelength range into electromagnetic radiation of a second wavelength range, - applying a second layer ( 2 ) on the first layer ( 1 ), the second layer ( 2 ) comprises a second phosphor which converts electromagnetic radiation of a first wavelength range into electromagnetic radiation of a third wavelength range.  The method of claim 1, wherein the first phosphor is based on at least one oxygen-containing inorganic compound.  A method according to any one of the preceding claims, wherein the second phosphor is based on a nitride or an oxynitride. Method according to one of the preceding claims, in which - the first layer ( 1 ) and the second layer ( 2 ) are ceramic, and - the first ceramic layer ( 1 ) and the second ceramic layer ( 2 ) by means of a joining layer ( 4 ) are materially connected. Method according to one of claims 1 to 3, in which - the second layer ( 2 ) is provided as a green sheet or as a green body and on the first layer ( 1 ), and - the layer composite comprising the first layer ( 1 ) and the second layer ( 2 ) is sintered. Method according to one of claims 1 to 3, wherein - a base material of the second layer ( 2 ) by a coating process on the first layer ( 1 ), and - the layer composite comprising the first layer ( 1 ) and the second layer ( 2 ) is sintered. Method according to one of Claims 5 to 6, in which the first layer ( 1 ) is provided as a finished ceramic layer. Method according to one of the preceding claims, in which between the first layer ( 1 ) and the second layer ( 2 ) a ceramic intermediate layer ( 5 ) having at least one of the following functions: - the ceramic intermediate layer ( 5 ) at least reduces the contact between the first layer ( 1 ) and the second layer ( 2 ), and / or - the ceramic intermediate layer ( 5 ) at least reduces the diffusion between the first layer ( 1 ) and the second layer ( 2 ), and / or - the ceramic intermediate layer ( 5 ) at least reduces the chemical reaction between the first layer ( 1 ) and the second layer ( 2 ), and / or - the ceramic intermediate layer ( 5 ) is the adhesion between the first layer ( 1 ) and the second layer ( 2 ). Process according to the preceding claim, in which the ceramic intermediate layer ( 5 ) comprises one of the following materials: alumina, aluminum nitride, silicon nitride, silica, yttria.  A method according to any preceding claim wherein the first phosphor is selected from the group consisting of rare earth or manganese doped garnets, rare earth or manganese doped aluminates, rare earth or manganese doped silicates such as orthosilicates or chlorosilicates.  A method according to any one of the preceding claims, wherein said second phosphor is selected from the group consisting of rare earth doped alkaline earth silicon nitrides, rare earth doped alkaline earth metal aluminum nitrides, rare earth doped alkaline earth metal halides. Ceramic conversion element ( 3 ) comprising: - a first ceramic layer ( 1 ) comprising a first phosphor which converts electromagnetic radiation of a first wavelength range into electromagnetic radiation of a second wavelength range, and a second ceramic layer ( 2 ) comprising a second phosphor which converts electromagnetic radiation of a first wavelength range into electromagnetic radiation of a third wavelength range.  A ceramic conversion element according to the preceding claim, wherein the first phosphor is based on at least one oxygen-containing inorganic compound.  A method according to any one of claims 12 to 13, wherein the second phosphor is based on a nitride or an oxynitride. Ceramic conversion element ( 3 ) according to one of claims 12 to 14, in which the main extension planes of the first ceramic layer ( 1 ) and the second ceramic layer ( 2 ) parallel to a main surface of the ceramic conversion element ( 3 ) are arranged. Ceramic conversion element ( 3 ) according to one of claims 12 to 15, in which the first ceramic layer ( 1 ) has a thickness of between 50 μm and 500 μm inclusive. Ceramic conversion element ( 3 ) according to one of claims 12 to 16, in which the second ceramic layer ( 2 ) has a thickness of between 2 μm and 200 μm inclusive. Method according to one of claims 12 to 17, in which between the first layer ( 1 ) and the second layer ( 2 ) a ceramic intermediate layer ( 5 ) having at least one of the following functions: - the ceramic intermediate layer ( 5 ) at least reduces the contact between the first layer ( 1 ) and the second layer ( 2 ), and / or - the ceramic intermediate layer ( 5 ) at least reduces the diffusion between the first layer ( 1 ) and the second layer ( 2 ), and / or - the ceramic intermediate layer ( 5 ) at least reduces the chemical reaction between the first layer ( 1 ) and the second layer ( 2 ), and / or - the ceramic intermediate layer ( 5 ) is the adhesion between the first layer ( 1 ) and the second layer ( 2 ). Optoelectronic semiconductor component comprising: - a semiconductor body ( 7 ), which emits in operation electromagnetic radiation of a first wavelength range, - a ceramic conversion element ( 3 ) according to one of claims 12 to 18, which at least partially converts electromagnetic radiation from the first wavelength range into radiation from the second wavelength range and the third wavelength range, so that the optoelectronic semiconductor component emits electromagnetic radiation of the first wavelength range, the second wavelength range and the third wavelength range.  An optoelectronic semiconductor device according to the preceding claim, wherein the first wavelength range blue light, the second wavelength range green to yellow light and the third wavelength range of orange to red light, and the optoelectronic semiconductor device emits mixed-colored radiation with a color point from the warm white area of the CIE standard color chart ,

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