Ceramic conversion element, optoelectronic semiconductor element and method for manufacturing a ceramic conversion element

Abstract

Ceramic conversion element (1) with: - a first ceramic layer (2) comprising a first phosphor (3) which converts electromagnetic radiation of a first wavelength range into electromagnetic radiation of a second wavelength range, and - a second ceramic layer (4) comprising a second phosphor (5) which converts electromagnetic radiation of the first wavelength range into electromagnetic radiation of a third wavelength range, wherein - the first phosphor (3) and the second phosphor (5) are different from each other, - the first phosphor (3) is chosen from the following group: (Gd,Y)3Al5O 12 :Ce 3+ , Tb3Al5O 12 :Ce 3+ , and the second phosphor (5) Sc3Al5O 12 :Ce 3+ is, - the first wavelength range is made up of blue light, the second wavelength range of yellow and / or red light, and the third wavelength range of green light.

Description

[0001] A ceramic conversion element, an optoelectronic semiconductor device with a ceramic conversion element, and a method for manufacturing a ceramic conversion element are described.

[0002] Ceramic conversion elements are described, for example, in the publications DE 10 2011 010 118 A1, DE 10 2011 113 962 A1, DE 10 2011 116 229 A1 and US 2008 / 0 187 746 A1. Publication DE 100 65 381 A1 describes, by way of example, a layered, resin-based conversion element. Publication DE 10 2012 104 274 A1 describes methods for manufacturing a ceramic conversion element.

[0003] One task is to specify a ceramic conversion element with two different phosphors that can be manufactured in a simplified manner. Furthermore, an optoelectronic semiconductor device with a ceramic conversion element and a method for manufacturing such a ceramic conversion element are to be specified.

[0004] These tasks are solved by a ceramic conversion element with the features of claim 1, by an optoelectronic semiconductor device with the features of claim 7 and by a method with the steps of claim 10.

[0005] Advantageous embodiments and further developments of the ceramic conversion element, the optoelectronic semiconductor device and the method for manufacturing the ceramic conversion element are specified in the dependent claims.

[0006] A ceramic conversion element comprises a first ceramic layer containing a first phosphor that converts electromagnetic radiation of a first wavelength range into electromagnetic radiation of a second wavelength range. The ceramic conversion element also comprises a second ceramic layer containing a second phosphor that converts electromagnetic radiation of a first wavelength range into electromagnetic radiation of a third wavelength range. The first and second phosphors are different from each other and each is based on at least one oxygen-containing inorganic compound.

[0007] Furthermore, the first wavelength range, the second wavelength range and the third wavelength range are also shaped differently from each other, although it is not excluded that the wavelength ranges may overlap with each other.

[0008] Preferably, the first ceramic layer is made entirely of a ceramic material. The second ceramic layer is also preferably made entirely of a ceramic material.

[0009] Preferably, the entire ceramic conversion element is made entirely of ceramic materials. Furthermore, the present ceramic conversion element is advantageously preferably a monolithic conversion element, meaning that the ceramic layers of the conversion element are bonded together in a material-bonded and mechanically stable manner without an adhesive layer. This offers the advantage of simplified handling, for example, compared to the use of individual conversion elements, each containing different phosphors.

[0010] Particularly preferred are a principal extension plane of the first ceramic layer and a principal extension plane of the second ceramic layer arranged parallel to a principal surface of the ceramic conversion element. In other words, the first ceramic layer and the second ceramic layer form a layer sequence in which a stacking direction is perpendicular to a principal surface of the ceramic conversion element.

[0011] According to one embodiment of the ceramic conversion element, the first ceramic layer and the second ceramic layer form a common interface. In other words, the first ceramic layer and the second ceramic layer can be arranged in direct contact with each other.

[0012] Oxygen-containing garnet phosphors are particularly preferred for the first and second phosphors. For example, the first and second phosphors are derived from the phosphor system Ln3(Al5O). 12 ):Ce 3+ , where Ln represents at least one of the following elements: Lutetium, Yttrium, Scandium, Gadolinium, Terbium.

[0013] The first phosphor is chosen from the following group: (Gd,Y)3Al5O 12 :Ce 3+ , Tb3Al5O 12 :Ce 3+ and the second phosphor is Sc3Al5O 12 :Ce 3+ .

[0014] The first ceramic layer preferably has a thickness between 50 µm and 300 µm inclusive. Particularly preferably, the first ceramic layer has a thickness between 80 µm and 150 µm inclusive.

[0015] The second ceramic layer particularly preferably has a thickness between 30 µm and 100 µm.

[0016] The entire ceramic conversion element preferably has a thickness between 80 µm and 250 µm inclusive.

[0017] According to one embodiment of the ceramic conversion element, a third ceramic layer is arranged between the first and second ceramic layers. This third ceramic layer comprises a third phosphor that converts electromagnetic radiation of the first wavelength range into electromagnetic radiation of a fourth wavelength range. The third phosphor is particularly preferably based on at least one oxygen-containing inorganic compound. The fourth wavelength range is further preferably different from the first, second, and third wavelength ranges, although it is not excluded that the fourth wavelength range overlaps with one of the other wavelength ranges.

[0018] Preferably, the first ceramic layer is free of the second phosphor and free of the third phosphor. Likewise, the second ceramic layer is preferably free of the first phosphor and free of the third phosphor. The third ceramic layer is also preferably free of the first phosphor and free of the second phosphor. However, it cannot be ruled out that the ceramic layers may be contaminated with the phosphors of the other layers, for example, due to tolerances in the manufacturing process. In other words, the various phosphors of the conversion element are preferably arranged spatially separated from one another in different layers, insofar as this is technically feasible. In this way, the reabsorption of already converted radiation by other phosphors can be advantageously at least reduced.

[0019] The first wavelength range consists of blue light. The second wavelength range consists of yellow and / or red light. The third wavelength range consists of green light. Such a conversion element is generally suitable, in conjunction with a light source emitting blue light, for emitting mixed-color radiation containing components of blue, yellow or yellow-red, and green radiation. Mixed-color radiation, comprising components of blue light from the first wavelength range, yellow or yellow-red light from the second wavelength range, and green light from the third wavelength range, typically has a comparatively broad spectrum, which is particularly suitable for use as a flash in a camera.

[0020] If the ceramic conversion element has a third ceramic layer, the first wavelength range preferably exhibits blue light or is composed of blue light. The second wavelength range particularly preferably exhibits yellow-red light or is composed of yellow-red light. The third wavelength range particularly preferably exhibits green light or is composed of green light. The fourth wavelength range particularly preferably exhibits yellow light or is composed of yellow light.

[0021] The third phosphor is preferably selected from the same phosphor system as the first and second phosphors. Particularly preferably, the third phosphor is also from the Ln3(Al5O) phosphor system. 12 ):Ce 3+ chosen where Ln represents at least one of the following elements: lutetium, yttrium, scandium, gadolinium, terbium. For example, the third phosphor is (Gd,Y)3Al5O12 :Ce 3+ .

[0022] The ceramic conversion element is particularly preferably intended for use in an optoelectronic semiconductor device, such as a light-emitting diode.

[0023] An optoelectronic semiconductor device comprises, in particular, a semiconductor body that, during operation, emits electromagnetic radiation of the first wavelength range from a radiation emission surface. Furthermore, the optoelectronic semiconductor device comprises the ceramic conversion element, which converts electromagnetic radiation from the first wavelength range, at least partially, into radiation from the second and third wavelength ranges, so that the optoelectronic semiconductor device emits electromagnetic radiation of the first, second, and third wavelength ranges.

[0024] For this purpose, the ceramic conversion element is preferably arranged in the beam path of the semiconductor body. For example, the ceramic conversion element can be arranged in direct contact with the radiation emission surface of the semiconductor body. In this way, particularly good heat dissipation of the conversion element during operation of the semiconductor device is possible. The ceramic conversion element can be bonded to the radiation emission surface, for example with a silicone.

[0025] The ceramic conversion element is particularly preferably configured such that it only partially converts the electromagnetic radiation from the semiconductor body into radiation from the second wavelength range and radiation from the third wavelength range, while a certain portion of the electromagnetic radiation from the first wavelength range emitted by the semiconductor body passes through the ceramic conversion element unconverted. In this way, the optoelectronic semiconductor device can emit mixed-color radiation, exhibit radiation from the first, second, and third wavelength ranges, or consist of radiation from the first, second, and third wavelength ranges.

[0026] The mixed-color radiation particularly preferably has a color point in the white, especially in the neutral white, area of ​​the CIE standard color chart.

[0027] Particularly preferred is the arrangement of the ceramic conversion element such that the ceramic layer faces the radiation-emitting surface of the semiconductor body, whose phosphor converts the radiation of the first wavelength range into radiation with the longest wavelengths. In other words, the ceramic layer with the phosphor that converts the light of the first wavelength range into the longest wavelength light is arranged so that it faces the semiconductor body and the light from the semiconductor body passes through this ceramic layer first. In this way, reabsorption of already converted light by one of the other phosphors can at least be reduced.

[0028] If the ceramic conversion element comprises more than two ceramic layers with different phosphors, the layers are particularly preferably arranged such that the wavelength ranges into which the ceramic layer converts the radiation of the first wavelength range contain smaller wavelengths with increasing distance from the semiconductor body.

[0029] A process for manufacturing the ceramic conversion element comprises the following steps: - Providing a first green film with a first phosphor suitable for converting electromagnetic radiation of a first wavelength range into electromagnetic radiation of a second wavelength range, - Providing a second green film with a second phosphor suitable for converting electromagnetic radiation of a first wavelength range into electromagnetic radiation of a third wavelength range, - Laminating the first green film with the second green film, and - Sintering of the layered composite with the first green film and the second green film, so that a ceramic conversion element is created, as already described.

[0030] The sintering of the layered composite is particularly preferred in a single sintering step. This simplifies the production of the ceramic conversion element.

[0031] The individual green films can themselves be made up of several green films laminated together. In this way, it is possible to create thicker ceramic layers.

[0032] Typically, the respective phosphor in particle form is incorporated into an organic matrix material for the production of the green films, which is then drawn into the green film. A method for producing a ceramic conversion element is described, for example, in German patent application DE 10 2012 104 274 A1.

[0033] The green film preferably has a thickness between 20 µm and 50 µm inclusive.

[0034] During the sintering process of the layered composite with the first green film and the second green film, the organic matrix material is particularly preferentially completely ashed.

[0035] The ceramic conversion element is based, among other things, on the idea of ​​selecting the first and second phosphors from a common phosphor system, which in this case is preferably oxygen-containing. In this way, it is possible to sinter the two different phosphors together without causing degradation of either phosphor due to the high temperatures required for sintering. This problem typically arises when combining a nitride phosphor—for example, to generate red light—with an oxide-containing phosphor—for example, to generate yellow light. Such a combination of phosphors can be used, for example, to generate white light when excited by a semiconductor body that emits blue light.

[0036] Furthermore, by using various phosphors, all of which are based on an oxygen-containing inorganic compound, it is advantageously possible to arrange the ceramic layers with these phosphors in direct contact with each other.

[0037] Further advantageous embodiments and developments of the invention will result from the exemplary embodiments described below in conjunction with the figures. The Fig. 1, Fig. 2 to Fig. Figure 3 shows a schematic sectional view of a ceramic conversion element according to one embodiment. Fig. Figure 4 shows a schematic sectional view of an optoelectronic semiconductor device according to an exemplary embodiment. Based on the Fig. 5, Fig. 6, Fig. 7, Fig. 8 to Fig. Section 9 describes an exemplary embodiment of a method for producing a ceramic conversion element. Fig. Figure 10 schematically shows the emission spectrum of a conventional optoelectronic device (curve A) and the emission spectrum of an optoelectronic device (curve B) according to Fig. 4.

[0038] Identical, similar, or similarly functioning elements are marked with the same reference symbols in the figures. The figures and the relative sizes of the elements depicted within them are not to be considered to scale. Rather, individual elements, particularly layer thicknesses, may be exaggerated for clarity and / or better understanding.

[0039] The ceramic conversion element 1 according to the embodiment of the Fig. 1 comprises a first ceramic layer 2 with a first phosphor 3. The first phosphor 3 is capable of converting blue light from a first wavelength range into yellow light. In other words, the second wavelength range in the embodiment according to the Fig. 1. Yellow light. The first phosphor 3 is, for example, Y3Al5O. 12 :Ce 3+ .

[0040] A second ceramic layer 4 is arranged in direct contact with the first ceramic layer 2. The second ceramic layer 4 has a second phosphor 5, which is suitable for converting blue light from the first wavelength range into green light. In the ceramic conversion element 1 according to the exemplary embodiment of the Fig. 1 both the first ceramic layer 2 and the second ceramic layer 4 are completely formed from a ceramic and arranged in direct contact with each other, so that the first ceramic layer 2 and the second ceramic layer 4 form a common interface.

[0041] The ceramic conversion element 1 according to Fig. 1 is monolithic, meaning that the first ceramic layer 2 and the second ceramic layer 4 are mechanically stable, metallurgically bonded, and connected to each other without a separate joining layer, for example by means of a sintering process. The ceramic conversion element 1 most preferably consists of the first ceramic layer 2 and the second ceramic layer 4.

[0042] The ceramic layers 2, 4 of the conversion element 1 comprise two different phosphors 3, 5, which, however, are both based on an oxygen-containing inorganic compound and are selected from a common phosphor system.

[0043] The ceramic conversion element 1 according to the embodiment of the Fig. 2 also comprises two ceramic layers 2, 4 with two different phosphors 3, 5. In contrast to the ceramic conversion element 1 according to the embodiment of the Fig. However, the first ceramic layer 2 contains a first phosphor 3 that is capable of converting blue light of the first wavelength range into red-yellow light. The first phosphor 3 is, for example, Tb3Al5O. 12 :Ce 3+ Otherwise, the ceramic conversion element 1 is according to Fig. 2 formed in the same way as the ceramic conversion element 1 according to Fig. 1.

[0044] The ceramic conversion element 1 according to the embodiment of the Fig. 3, unlike the ceramic conversion elements 1, exhibits according to the Fig. 1 and Fig. The device consists of three ceramic layers. The first ceramic layer contains the first phosphor 3, which is capable of converting blue light of the first wavelength range into yellowish to red light. The first phosphor 3 is, for example, Tb3Al5O. 12 :Ce 3+ .

[0045] The second ceramic layer 4 has the second phosphor 5, which is suitable for converting blue light of the first wavelength range into green light of the second wavelength range.

[0046] A third ceramic layer 6 is arranged between the first ceramic layer 2 and the second ceramic layer 4. The third ceramic layer 6 comprises a third phosphor 7, which is capable of converting radiation of the first wavelength range into radiation from a third wavelength range. In the present embodiment, the third wavelength range includes yellow light. The third phosphor 7 is, for example, Y3Al5O. 12 :Ce 3+ .

[0047] The three ceramic layers 2, 4, 6 are arranged in direct contact with each other. The ceramic conversion element 1 particularly preferably consists of the three ceramic layers 2, 4, 6.

[0048] The ceramic conversion element 1 is designed to be arranged such that radiation of the first wavelength range passes first through the first ceramic layer 2, then through the second ceramic layer 4, and then through the third ceramic layer 6. In this way, the radiation of the first wavelength range is partially converted first into red-yellow light, then partially into yellow light, and finally partially into green light. In other words, the ceramic layers 2, 4, and 6 are arranged such that the wavelength ranges into which the ceramic layers 2, 4, and 6 each convert the radiation of the first wavelength range contain shorter wavelengths with increasing distance from the light source.

[0049] The optoelectronic semiconductor device according to the embodiment of the Fig. 4 has a component housing 8 with a recess 9. A semiconductor body 10 is mounted on the bottom of the component housing 8 and is electrically contacted on its front side via a bond wire 11.

[0050] The semiconductor body 10 is suitable for emitting electromagnetic radiation of a first wavelength range during operation, which is emitted from a radiation exit surface 12. In this case, the first wavelength range consists of blue radiation.

[0051] A ceramic conversion element 1 is applied to the radiation emission surface 12 of the semiconductor body 10, as already shown in the figure. Fig. 1 or Fig. 2 was described. It is also possible that a different conversion element 1, for example according to Fig. 3 is arranged on the radiation emission surface 12.

[0052] The blue radiation of the first wavelength range, emitted from the radiation emission surface 12 of the semiconductor body 10, passes through the ceramic conversion element 1. Here, a portion of the blue radiation is converted into yellow or red-yellow light by the first phosphor 3 of the first ceramic layer 2. The blue radiation then passes through the second ceramic layer 4 and is partially converted into green light by the second phosphor 5. The remaining portion of the blue light from the semiconductor body 10 passes through the conversion element 1 unconverted. In this way, the optoelectronic semiconductor device emits light according to the exemplary embodiment shown. Fig. 4 mixed-color, white radiation, which includes blue radiation of the first wavelength range, red-yellow radiation of the second wavelength range and green radiation of the third wavelength range and has a color locus in the white range.

[0053] The recess 9 of the component housing 8 is in this case still filled with a potting compound 13, which surrounds and protects the semiconductor body 10.

[0054] In the procedure according to the exemplary embodiment of the Fig. 5, Fig. 6, Fig. 7, Fig. 8 to Fig. In a first step, a base material 14 for a green film is produced (not shown). For this purpose, an inorganic first phosphor 3 in particle form is incorporated into an organic matrix material. The base material 14 is then drawn into a green film 15 ( Fig. 5). In the same way, another green film 16 is produced with a second phosphor 5 (not shown).

[0055] A first green film 15 and a second green film are now available ( Fig. 6) The first green film 15 comprises a first phosphor 3, which is suitable for converting electromagnetic radiation of the first wavelength range into electromagnetic radiation of the second wavelength range. The second green film 16 comprises a second phosphor 5, which is suitable for converting electromagnetic radiation of the first wavelength range into electromagnetic radiation of a third wavelength range.

[0056] In the next step, the two green films 15, 16 are laminated together ( Fig. 7) The two green films 15, 16 are in direct contact with each other. Finally, the layer sequence with the first green film 15 and the second green film 16 is sintered, resulting in a plate-shaped ceramic element 17.

[0057] The plate-shaped ceramic element 17 is then divided in a further step along several dividing lines 18 into individual ceramic conversion elements 1 ( Fig. 8). A wide variety of ceramic conversion elements 1 are now available ( Fig. 9), as can be seen, for example, from the Fig. 1 and Fig. 2 have already been described.

[0058] To produce a ceramic conversion element 1 with three different ceramic layers 2, 4, 6, three different green films are provided analogously, laminated together and sintered.

[0059] The solid curve A in Fig. Figure 10 shows the relative intensity I as a function of wavelength λ emitted by a conventional optoelectronic semiconductor device in which the first phosphor 3 and the second phosphor 8 are contained in particle form in the encapsulation 13. The first phosphor 3 is Y3Al5O 12:Ce 3+ and in the second phosphor 5 µm Lu3Al5O 12 :Ce 3+ .

[0060] Furthermore, it shows Fig. 10 the relative intensity I as a function of wavelength λ emitted by an optoelectronic semiconductor device containing a conversion element 1, as determined by Fig. As already described (curve B, dashed line), the first phosphor 3 and the second phosphor 5 are arranged separately in two different ceramic layers 2, 4. The first phosphor 3 is again Y3Al5O. 12 :Ce 3+ and in the case of the second phosphor 5, also Lu3Al5O 12 :Ce 3+A comparison of the two curves shows that by arranging the two phosphors 3, 5 in two separate ceramic layers 2, 4 the conversion efficiency can be improved and also lower losses of radiation from certain wavelength ranges due to reabsorption occur.

Claims

[1] Ceramic conversion element (1) with: - a first ceramic layer (2) comprising a first phosphor (3) which converts electromagnetic radiation of a first wavelength range into electromagnetic radiation of a second wavelength range, and - a second ceramic layer (4) comprising a second phosphor (5) which converts electromagnetic radiation of the first wavelength range into electromagnetic radiation of a third wavelength range, wherein - the first phosphor (3) and the second phosphor (5) are different from each other, - the first phosphor (3) is chosen from the following group: (Gd,Y)3Al5O 12 :Ce 3+ , Tb3Al5O 12 :Ce 3+ , and the second phosphor (5) Sc3Al5O 12 :Ce 3+ is, - the first wavelength range is made up of blue light, the second wavelength range of yellow and / or red light, and the third wavelength range of green light. [2] Ceramic conversion element (1) according to the above claim, wherein a principal extent plane of the first ceramic layer (2) and a principal extent plane of the second ceramic layer (4) are arranged parallel to a principal surface of the ceramic conversion element (1). [3] Ceramic conversion element (1) according to one of the above claims, wherein the first ceramic layer (2) and the second ceramic layer (4) form a common interface. [4] Ceramic conversion element (1) according to one of claims 1 or 2, in which a third ceramic layer (6) is arranged between the first ceramic layer (2) and the second ceramic layer (4), the third ceramic layer (6) comprising a third phosphor (7) which converts electromagnetic radiation of the first wavelength range into electromagnetic radiation of a fourth wavelength range and is based on at least one oxygen-containing inorganic compound. [5] Ceramic conversion element (1) according to any of the above claims, wherein the first ceramic layer (2) has a thickness between 50 µm inclusive and 300 µm inclusive. [6] Ceramic conversion element (1) according to one of the above claims, wherein the second ceramic layer (4) has a thickness between 30 µm inclusive and 100 µm inclusive. [7] Optoelectronic semiconductor device with: - a semiconductor body (10) which, during operation, emits electromagnetic radiation of a first wavelength range from a radiation emission surface (12), - a ceramic conversion element (1) according to one of the above claims, which converts electromagnetic radiation from the first wavelength range at least partially into electromagnetic radiation from the second wavelength range and the third wavelength range, so that the optoelectronic semiconductor device emits electromagnetic radiation of the first wavelength range, the second wavelength range and the third wavelength range. [8] Optoelectronic semiconductor device according to the previous claim, which emits mixed-color radiation with a color point in the white area of ​​the CIE standard color chart. [9] Optoelectronic semiconductor device according to one of claims 7 to 8, in which the ceramic conversion element (1) is arranged such that the ceramic layer (2, 4, 6), whose phosphor (3, 5, 7) converts the electromagnetic radiation of the first wavelength range into electromagnetic radiation with the longest wavelength, points towards the radiation emission surface (12) of the semiconductor body (10). [10] Method for producing a ceramic conversion element (1) comprising the following steps: - Providing a first green film (15) with a first phosphor (3) suitable for converting electromagnetic radiation of a first wavelength range into electromagnetic radiation of a second wavelength range, - Providing a second green film (16) with a second phosphor (5) suitable for converting electromagnetic radiation of a first wavelength range into electromagnetic radiation of a third wavelength range, and - Laminating the first green film (15) with the second green film (16), and - Sintering of the layered composite with the first green film (15) and the second green film (16), so that a ceramic conversion element (1) with: - a first ceramic layer (2) comprising the first phosphor (3) which converts electromagnetic radiation of the first wavelength range into electromagnetic radiation of the second wavelength range, and - a second ceramic layer (4) comprising the second phosphor (5) which converts electromagnetic radiation of the first wavelength range into electromagnetic radiation of the third wavelength range, wherein - the first phosphor (3) and the second phosphor (5) are based on at least one oxygen-containing inorganic compound and are different from each other, whereby - the first phosphor (3) is chosen from the following group: (Gd,Y)3Al5O 12 :Ce 3+ , Tb3Al5O 12 :Ce 3+ , and the second phosphor (5) Sc3Al5O 12 :Ce 3+ is. [11] Method according to the previous claim, wherein the sintering of the layer composite takes place in a single sintering step.

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