Optoelectronic semiconductor chip

Abstract

In one embodiment, the optoelectronic semiconductor chip (1) comprises a semiconductor layer sequence (2) having an active region (23) for generating radiation having a wavelength L of maximum intensity. The mirror (3) comprises a cover layer (31). The cover layer (31) is made of a radiation-permeable material and has an optical thickness of between 0.5 L and 3 L, including a boundary value. Between two and ten intermediate layers (32, 33, 34, 35) of the mirrors (3) are followed by the cover layer (31) in a direction away from the semiconductor layer sequence (2), wherein a boundary value is included. The intermediate layers (32, 33, 34, 35) alternately have a high refractive index and a low refractive index. The optical thickness of the at least one intermediate layer (32, 33, 34, 35) is not equal to L / 4. At least one metal layer (39) of the mirror (3) is followed by the intermediate layer (32, 33, 34, 35) in a direction away from the semiconductor layer sequence (2) as a reflective layer.

Description

[0001] This invention application is a divisional application of the invention patent application filed on March 14, 2019, with application number "201980019438.5" and invention title "Optoelectronic Semiconductor Chip". Technical Field

[0002] A photoelectric semiconductor chip is proposed. Summary of the Invention

[0003] The objective is to propose an optoelectronic semiconductor chip having a mirror with high reflectivity.

[0004] The stated objective is also achieved by an optoelectronic semiconductor chip having the features of the independent claim. Preferred improvements are the subject of the remaining claims.

[0005] According to at least one embodiment, the optoelectronic semiconductor chip is configured to generate radiation, particularly near-ultraviolet radiation, visible light, and / or near-infrared radiation. The semiconductor chip is, for example, a light-emitting diode (LED) chip or a laser diode (laser diode) chip. Preferably, the semiconductor chip is an LED chip for generating yellow, orange, or red light.

[0006] According to at least one embodiment, a semiconductor chip includes a sequence of semiconductor layers. The semiconductor layer sequence includes at least one active region for generating radiation. The radiation has a wavelength L of maximum intensity. The active region is preferably located between the p-type doped side and the n-type doped side of the semiconductor layer sequence. Single quantum well structures, multiple quantum well structures, and / or pn junctions are particularly present in the active region. The active region extends particularly perpendicular to the growth direction of the semiconductor layer sequence.

[0007] The semiconductor layer sequence is preferably based on a group III-V compound semiconductor material. Examples of semiconductor materials include nitride compound semiconductor materials, such as Al. n In 1-n-m Ga m N, or phosphide compound semiconductor materials, such as Al n In 1-n-m Ga m P, or arsenic compound semiconductor materials, such as Al n In 1-n-m Ga m As or such as Al n Ga m In 1-n-m As k P 1-kThe following conditions are met: 0 ≤ n ≤ 1, 0 ≤ m ≤ 1 and n + m ≤ 1, and 0 ≤ k < 1. Preferably, 0 < n ≤ 0.8, 0.4 ≤ m < 1 and n + m ≤ 0.95, and 0 < k ≤ 0.5 apply to at least one layer of the semiconductor layer sequence or to all layers. The semiconductor layer sequence may have dopants and additional components. For simplicity, only the main components of the lattice of the semiconductor layer sequence, namely Al, As, Ga, In, N, or P, are described, even if these components can be partially replaced and / or supplemented by small amounts of other substances.

[0008] According to at least one embodiment, the semiconductor chip includes one or more mirrors. Preferably, exactly one mirror is used for reflecting radiation. The mirror is disposed on the back side of the semiconductor layer sequence, opposite to the optically coupled output side of the semiconductor layer sequence.

[0009] According to at least one embodiment, the mirror includes at least one, preferably exactly one, capping layer. The capping layer may be the thickest layer of the mirror, particularly the thickest layer of the mirror made of a material permeable to radiation generated during operation. The capping layer is the layer of the mirror closest to the semiconductor layer sequence. The capping layer may planarly contact the semiconductor layer sequence.

[0010] According to at least one embodiment, the capping layer is made of a material permeable to radiation generated during operation, particularly a material with a low refractive index. A low refractive index can mean that the refractive index of the capping layer is at least 0.5, 1, or 1.5 less than the average refractive index of the semiconductor layer sequence. Preferably, the capping layer is made of a dielectric material, but alternatively, it can also be made of a conductive material. The material of the capping layer is, for example, an oxide, a nitride, or an oxynitride.

[0011] According to at least one embodiment, the capping layer has a relatively large optical thickness. The term optical thickness refers to the product of the geometric thickness of the respective layer and its refractive index with respect to the wavelength of maximum intensity. Preferably, the capping layer has an optical thickness of at least 0.5L or 1.0L. Alternatively or additionally, the optical thickness is up to 5L, 3L, 2L, or 1.5L.

[0012] The wavelength L of maximum intensity refers to the vacuum wavelength, both here and below. If the vacuum wavelength is, for example, 600 nm, then the value of 0.5L corresponds to a thickness of 300 nm. If the optical thickness is expressed in terms of, for example, 300 nm and the refractive index at wavelength L is, for example, 1.5, then the geometric thickness associated with the corresponding optical thickness is thus 200 nm, calculated by dividing the refractive index by 300 nm. In other words, the so-called optical thickness is relative to the wavelength L of maximum intensity, where the refractive index of the relevant layer is used as the divisor to convert to geometric thickness. The refractive index relates to a temperature of 300 K or the suitable operating temperature of the semiconductor chip.

[0013] According to at least one embodiment, the mirror includes a plurality of intermediate layers. The number of intermediate layers is preferably a maximum of fifteen, ten, or seven. Along the direction away from the semiconductor layer sequence, the intermediate layers follow the capping layer, particularly directly following it. Two, three, four, or five intermediate layers are particularly common, with three or four intermediate layers being especially preferred.

[0014] According to at least one embodiment, each intermediate layer is made of a material permeable to radiation generated during operation, such as oxides, nitrides, or oxynitrides. The intermediate layers can be dielectric or alternatively conductive. The intermediate layers are composed of at least two different materials, wherein each intermediate layer is preferably composed of a single material. Along the direction away from the capping layer, the intermediate layers alternately have high and low refractive indices to radiation generated during operation. The refractive index difference between adjacent intermediate layers and / or with the capping layer is preferably at least 0.5 or 1. It is possible that an intermediate layer, particularly one with a low refractive index, is made of the same material as the capping layer.

[0015] According to at least one embodiment, the thickness of at least one intermediate layer is not equal to L / 4. In other words, at least one intermediate layer is not a layer as used in conventional Bragg mirrors. It is possible that no intermediate layer has a thickness of L / 4. This is particularly applicable with tolerances of 0.03L, 0.02L, or 0.01L.

[0016] According to at least one embodiment, the mirror includes a metal layer. The metal layer follows an intermediate layer, particularly directly, in a direction opposite to the semiconductor layer sequence. The metal layer is configured as a reflective layer and is used to reflect radiation generated during operation. Radiation originating from the semiconductor layer sequence, passing through the capping layer and intermediate layers, and reaching the metal layer is reflected on the metal layer.

[0017] In at least one embodiment, the optoelectronic semiconductor chip includes a sequence of semiconductor layers having an active region for generating radiation of wavelength L with maximum intensity. A mirror for radiation is located on a back side, opposite to the optically coupled output side. The mirror includes a capping layer closest to the semiconductor layer sequence. The capping layer is made of a radiation-permeable material and has an optical thickness between 0.5L and 3L (including boundary values). Following the capping layer in a direction away from the semiconductor layer sequence are two to ten intermediate layers (including boundary values) with the mirror. The intermediate layers alternately have high and low refractive indices for radiation and are each made of a radiation-permeable material. The optical thickness of at least one intermediate layer is not equal to L / 4. Following the intermediate layers in a direction away from the semiconductor layer sequence are at least one metal layer with the mirror as a reflective layer.

[0018] Therefore, the mirror is a particularly dielectric Bragg mirror used over a wide wavelength range, such as the spectral range from yellow to infrared. The mirror is preferably used in light-emitting diode (LED) chips based on InGaAlP and / or AlGaAs.

[0019] The enhanced reflectivity can be achieved, particularly by means of the mirror described herein, using dielectric mirrors especially for thin-film LEDs, where the growth substrate is located away from the semiconductor layer sequence. This is applicable, for example, to InGaAlP-based LED chips manufactured using thin-film technology, or TF technology for short.

[0020] A key component in thin-film technology, such as that used in InGaAlP / AlGaAs diodes, is a dielectric-metal mirror. The first part of this mirror consists of a thick layer of dielectric material. The dielectric material of this first layer should have a low refractive index to maximize the refractive index difference between the adjacent semiconductor material and the first mirror layer, thereby maximizing the critical angle for total internal reflection. The metal behind the dielectric layer, typically Au or Ag, reflects light, but not at the first boundary surface.

[0021] InGaAs / AlGaAs chips manufactured using Osram's TF technology, such as the TF5 and TF6 configurations, use mirrors consisting of, for example, a thick SiO2 layer with a thickness of 530 nm and an Au layer behind it. Other variations of dielectric mirrors exist in InGaAlP / AlGaAs diodes from other manufacturers; however, these always have only a single dielectric layer, such as MgF2 in the case of EpiStar. For GaN light-emitting diodes, it has been proposed to improve mirror reflectivity by introducing a so-called dielectric DBR, i.e., a distributed Bragg reflector. Such mirrors are composed of pairs of layers, such as SiO2 / TiO2, with a thickness of L / 4, for example, see publication Hongjun Chen et al., “Enhanced Performance of GaN-Based Light-Emitting Diodes by Using Al Mirror and Atomic Layer Deposition-TiO2 / Al2O3 Distributed Bragg Reflector Backside Reflector with Patterned SapphireSubstrate”, Applied Physics Express, Vol. 6, No. 2, 2013, DOI: https: / / doi.org / 10.7567 / APEX.6.022101.

[0022] The basic concept of the mirror described here is to use a stack of dielectric layers with optimal thickness instead of a single SiO2 layer. Traditional DBR mirrors consist of multiple L / 4 layers made of two dielectric materials. The materials should have a large refractive index difference to maximize reflection of radiation at each boundary surface. A drawback of this conventional approach is that this construction results in strong angular and spectral dependence of reflection. This means that the L / 4 construction does not improve mirror reflectivity when considering angular integrals.

[0023] The Bragg mirror proposed here differs from the traditional DBR at several points:

[0024] 1) The first dielectric layer near the semiconductor material has a low refractive index and a thickness of such that a large critical angle for total internal reflection is achieved at the first boundary surface.

[0025] 2) The layers behind it are not L / 4 thick to avoid angular and spectral minimums. The thickness of these layers is chosen such that they ensure high structural interference of reflected light at each boundary surface, while exhibiting very weak wavelength and angular dependence.

[0026] 3) The number of layers behind it is preferably reduced to three or four to reduce design complexity and minimize the adverse effects on the thermal conductivity through the LED.

[0027] The aforementioned dielectric stacking improves the specular reflectivity and brightness of InGaAlP light-emitting diodes, in particular.

[0028] In particular, the following aspects should be considered:

[0029] A) Selecting dielectric materials:

[0030] As mentioned above, the dielectric material should be chosen to have a sufficiently high refractive index difference. The first layer should be a low-refractive-index layer. Examples of suitable material pairs are: i) SiO2 with n = 1.46 and / or Nb2O5 with n = 2.3, ii) SiO2 and TiO2 with n = 2.3 to 2.4, iii) MgF2 and Nb2O5 with n = 1.37, and iv) MgF2 and TiO2. The values ​​mentioned apply to a temperature of 300 K and a wavelength of 616 nm. For different material choices, it is preferable to further optimize the thickness of each layer.

[0031] B) Number and thickness of layers:

[0032] The total number of layers can be low, for example, three or four. It is advantageous to limit the number of layers because a thicker dielectric mirror has a detrimental effect on the thermal properties of the LED. To maximize reflectivity over a wide angular and spectral range, it is advantageous that these layers differ from L / 4 and have different optical thicknesses for the low- and high-refractive-index layers. For example, the first layer is thick, specifically around 520 nm. The underlying Nb₂O₅ and SiO₂ layers have thicknesses slightly greater than or less than L / 3, respectively. For these designs, there is no strong minimum reflectivity with respect to angle.

[0033] However, an equivalent configuration exists:

[0034] i) The thickness of the first layer can be chosen to be greater or less. However, if the first layer is too thin, for example, thinner than about L / 2, then loss of reflection is improved.

[0035] ii) For thinner dielectric layers, it is not necessary for layers of the same material to have the same optical thickness. Equivalent designs exist where each layer has a different optical thickness. A thickness greater than L / 4, but less than L / 2, preferably L / 3 + / - 20%, is optimal.

[0036] iii) It is possible to use different numbers of dielectric layers. The total number of layers can be greater than 4. Good design schemes exist with both odd and even numbers of layers.

[0037] iv) When using an odd number of dielectric layers, each layer can be L / 4 thick or thinner. However, if an L / 4 thickness is chosen, there is a minimum reflectivity at a specific angle. This reduces the overall integral reflectivity of the mirror.

[0038] C) Choose a metal behind the dielectric layer:

[0039] The broadband spectral reflectance Bragg mirror described herein can be used in conjunction with Au, Ag, or Al as a metallic mirror layer or any other metallic mirror behind it. For good adhesion of the dielectric layer to the metallic mirror, it is preferable to use an additional thin adhesion layer, such as an adhesion layer made of transparent conductive oxides, abbreviated as TCO, such as ITO, ZnO, or other similar materials. Other possible materials include insulating oxides such as Al₂O₃ or metals such as Ti.

[0040] D) Use in different chip designs, such as in combination with p-type contacts:

[0041] i) The dielectric layer stack of the mirror is deposited directly on the semiconductor material. To contact the semiconductor, the mirror is structured, for example, by photolithography. The semiconductor material is preferably contacted via metal contacts, such as point contacts.

[0042] ii) Contact and current propagation are achieved through a thin TCO layer, for example, made of ITO. A Bragg stack is then deposited on the TCO layer and structured to allow the TCO to be contacted via metal contact points. Such TCO contacts, particularly on GaP, are illustrated in publication DE 10, for example.

[0043] As is known in 2017 101 637A1, the disclosure of which is incorporated herein by reference. Other TCOs such as IZO or ZnO are also feasible, either individually or in combination.

[0044] iii) The application of Bragg mirrors combined with TCO layers as contact layers also offers advantages for subsequent processing. Bragg mirrors are typically structured using dry etching to avoid under-etching if the two dielectric materials have different etch rates in a wet etching process. However, direct dry etching on semiconductor materials can introduce defects and make the formation of low-ohmic electrical contacts more difficult.

[0045] Dry etching on TCO does not affect the contact resistance.

[0046] iv) For conventional DBR mirrors, significant variations in light distribution are expected due to strong angular and spectral correlations in the reflection pattern. In the case of the broadband Bragg mirror described herein, the light distribution remains Lambertian. Light distribution was measured for an LED chip with a single SiO2 layer and the mirror design described herein; no deviation was determined in terms of reflection characteristics.

[0047] According to at least one embodiment, the semiconductor chip includes one or more adhesion layers and / or one or more contact layers. The adhesion layer is preferably located between a metal layer and a final dielectric mirror layer. Preferably, the adhesion layer is planar and directly adjacent to the metal layer and the adjacent dielectric layer. The contact layer is preferably disposed directly between a capping layer and a sequence of semiconductor layers.

[0048] According to at least one embodiment, the adhesion layer and / or contact layer are made of transparent conductive oxide.

[0049] Transparent conductive oxides (TCOs) are transparent conductive materials, typically metal oxides such as zinc oxide, tin oxide, cadmium oxide, titanium oxide, indium oxide, or indium tin oxide (ITO). Besides binary metal oxides such as ZnO, SnO2, or In2O3, ternary metal oxides such as Zn2SnO4, CdSnO3, ZnSnO3, MgIn2O4, GaInO3, Zn2In2O5, or In4Sn3O3 are also included. 12Mixtures of different transparent conductive oxides also belong to the TCO family. Furthermore, TCOs are not strictly required to correspond to a stoichiometric composition and can be p-type doped or n-type doped.

[0050] According to at least one embodiment, the adhesion layer and / or contact layer have a relatively small optical thickness. Due to the small thickness of the adhesion layer and / or contact layer, these adhesion layers and / or contact layers are likely non-functional. In particular, the optical thickness of the adhesion layer and / or contact layer is at most L / 5, L / 7, or L / 9. For example, the geometric thickness of the adhesion layer and / or contact layer is at least 0.5 nm, 2 nm, or 5 nm and / or at most 250 nm, 100 nm, 40 nm, or 30 nm.

[0051] According to at least one embodiment, at least 30%, 50%, or 80% of, or all of, the intermediate layers have an optical thickness of L / 3. This optical thickness is particularly present with a tolerance of a maximum of L / 15, 0.06L, L / 20, or L / 30. It is possible that only one or only two intermediate layers also have an optical thickness of L / 3, having the aforementioned tolerance.

[0052] According to at least one embodiment, the mirror has exactly three intermediate layers. Alternatively, the mirror has exactly four intermediate layers. That is, together with the capping layer, the mirror then comprises exactly four or exactly five layers made of a material that preferably has alternating high and low refractive indices along a direction away from the semiconductor layer sequence and is made of a material that is permeable to radiation.

[0053] According to at least one embodiment, the mirror has at most one, two, or three intermediate layers, said intermediate layers exhibiting an optical thickness of (L / 4 + N / 2) + / - L / 20. N is a natural number greater than or equal to zero. Alternatively or additionally, these intermediate layers constitute at most 60%, 40%, or 20% of the total number of intermediate layers in the mirror.

[0054] Alternatively, the intermediate layers may not have this optical thickness. That is, the mirror may not have an L / 4 layer or may have essentially no L / 4 layer, which is used in conventional Bragg mirrors.

[0055] According to at least one embodiment, the optical thickness of the cover layer is at least 0.9L, L, 1.1L, or 1.2L. Alternatively or additionally, the optical thickness of the cover layer is at most 1.8L, 1.6L, or 1.4L. In particular, the optical thickness of the cover layer is between 1.15L and 1.3L.

[0056] According to at least one embodiment, the intermediate layer, or at least one or at least half of the intermediate layers, has an optical thickness of at least 0.27L, 0.3L, or 0.32L. Alternatively or additionally, the optical thickness of the associated intermediate layer is at most 0.43L, 0.4L, or 0.36L. Preferably, exactly two such intermediate layers are present.

[0057] According to at least one embodiment, the mirror has a low-refractive-index intermediate layer located therebetween, preferably disposed directly between two intermediate layers listed in the preceding paragraph. The intermediate layer located therebetween preferably has an optical thickness of at least 0.26L or 0.28L and / or a maximum of 0.38L or 0.35L or 0.31L. Preferably, the refractive index difference between these low-refractive-index intermediate layers and the adjacent intermediate layers is at least 0.04L or 0.06L or 0.08L, respectively.

[0058] According to at least one embodiment, the optical thickness of at least three intermediate layers increases in the direction away from the cover layer. This is particularly suitable for intermediate layers that follow each other. The intermediate layers preferably begin at the cover layer. The difference in optical thickness between adjacent intermediate layers of this type is preferably at least 0.03L or 0.06L and / or a maximum of 0.2L or 0.15L or 0.1L.

[0059] According to at least one embodiment, the optical thickness of at least three intermediate layers increases in the direction away from the metal layer. This is preferably applicable to intermediate layers that follow each other directly and especially to those that begin directly at the metal layer. The difference in optical thickness between these adjacent intermediate layers is preferably relatively large and, for example, at least 0.06L, 0.09L, or 0.11L and / or a maximum of 0.18L, 0.14L, or 0.12L.

[0060] According to at least one embodiment, the optical thickness of one or more intermediate layers is a maximum of L / 5. In particular, there is exactly one such relatively thin intermediate layer. The one or more intermediate layers are preferably closer to the metal layer than the capping layer. Preferably, an intermediate layer with a small thickness is located, for example, directly on the metal layer.

[0061] According to at least one embodiment, the total optical thickness of the capping layer, together with all intermediate layers, is at least 1.6L, 1.8L, or 2.1L. Alternatively or additionally, the total thickness is at most 3.5L, 2.7L, or 2.3L. In other words, the total thickness is relatively small.

[0062] For all the preceding and following optical thicknesses of the capping layer and intermediate layers, it is applicable to add n L / 2, where n is a natural number greater than or equal to one, especially equal to 1, i.e., n = 1. By increasing the optical thickness by n L / 2, the optical effect of the relevant layer does not change or does not change significantly. To simplify the foregoing description of the thickness, however, the optional addition of n L / 2 is not usually given together. However, it is particularly preferred to omit the addition, such that n = 0.

[0063] According to at least one embodiment, the intermediate layer, or the last intermediate layer, i.e., the intermediate layer closest to the metal layer, has a thickness not equal to L / 4. Preferably, the optical thickness of these intermediate layers is between 0.28L and 0.45L, or, for the case of n=1, between 0.78L and 0.95L. In this case, preferably at least 50% or 75% of the remaining intermediate layers, or all of the remaining intermediate layers, have an optical thickness between 0.255L and 0.45L (including boundary values) or between 0.755L and 0.95L (including boundary values). This is particularly applicable when the last intermediate layer closest to the metal layer is a high-refractive-index layer.

[0064] According to at least one embodiment, the last intermediate layer closest to the metal layer has an optical thickness between 0.28L and 0.48L (including boundary values). This is particularly suitable when the last intermediate layer is a low-refractive-index layer.

[0065] According to at least one embodiment, the intermediate layer, optionally together with the cover layer, is composed of exactly two different materials. That is, the mirror, together with the metal layer, is preferably composed of only three different materials.

[0066] According to at least one embodiment, the mirror is composed of more than two light-transmitting materials, such as three or four. It is feasible that the intermediate layer comprises at least two of these materials and the cover layer is composed of another material. Furthermore, it is feasible that each intermediate layer, or each of the intermediate layers together with the cover layer, is composed of its own material.

[0067] According to at least one embodiment, the cover layer, all intermediate layers, and metal layers follow each other directly and preferably planarly. There are no other components between the aforementioned components.

[0068] According to at least one embodiment, the cover layer, the intermediate layer, and the optional metal layer are all flat layers with a constant thickness. The cover layer, the intermediate layer, and the optional metal layer may extend overlappingly. It is possible that the cover layer and / or the intermediate layer extend laterally beyond the metal layer to provide encapsulation of the metal layer's impact relative to the external environment.

[0069] According to at least one embodiment, the semiconductor layer sequence and / or contact layer are structured. Consequently, these layers have an uneven morphology. A mirror can follow this morphology, in particular, retain it. That is, the capping layer, intermediate layer, and / or metal layer are thus formed unevenly.

[0070] According to at least one embodiment, the capping layer and the low-refractive-index intermediate layer are respectively made of silicon dioxide or magnesium difluoride. Nb₂O₅ or titanium dioxide are particularly used as materials for the high-refractive-index intermediate layer. Specifically, the capping layer and the low-refractive-index intermediate layer are composed of silicon dioxide, while the high-refractive-index intermediate layer is composed of Nb₂O₅. Here, the capping layer and the intermediate layer generally preferably alternate between high and low refractive indices, starting with the low-refractive-index capping layer.

[0071] According to at least one embodiment, the metal layer is made of gold, a gold alloy, silver, a silver alloy, or aluminum or an aluminum alloy. The thickness of the metal layer is preferably at least 50 nm, 100 nm, or 200 nm. The metal layer is preferably located directly on the intermediate layer.

[0072] Alternatively, a metal layer can be disposed between the intermediate layer and the metal layer, such as a titanium layer, a platinum layer, and / or a palladium layer. This adhesion-improving layer is preferably optically ineffective and, in particular, has a maximum thickness of 5 nm, 2 nm, or 1 nm. Furthermore, the adhesion-improving layer can be composed of a dielectric oxide, such as aluminum oxide, or a TCO.

[0073] According to at least one embodiment, the metal layer of the mirror is ohmically conductively connected to an electrode of the semiconductor chip, or the metal layer forms part of an electrode. That is, current is applied to the semiconductor layer sequence, particularly the p-type doped side of the semiconductor layer sequence, via the metal layer. In other words, the mirror can be located on the p-type doped side.

[0074] According to at least one embodiment, the semiconductor chip includes one or more vias for electrical contact, particularly on the p-type doped side. One or all of the vias preferably extend through a mirror, i.e., particularly through the capping layer and through all intermediate layers. Thus, the metal layer of the mirror can be electrically connected to a sequence of semiconductor layers or an additional contact layer via the vias.

[0075] According to at least one embodiment, the contact layer extends continuously through all vias. Thus, the contact layer can simultaneously serve as a current spreading layer. The adhesion promoter layer can also be structured in at least one contact region and subsequently does not need to be conductive.

[0076] According to at least one embodiment, the semiconductor layer sequence is based on the material system AlInGaAs and / or the material system InGaAlP. In other words, the semiconductor chip is a device based on arsenide or phosphide. The wavelength L of maximum intensity is preferably at least 570 nm or 590 nm and / or a maximum of 950 nm or 840 nm or 700 nm. In particular, red light is generated during normal operation by means of the semiconductor chip. Attached Figure Description

[0077] The optoelectronic semiconductor chip described herein will now be described in detail with reference to the accompanying drawings and embodiments. The same reference numerals denote the same elements in the various drawings. However, no proportional relationship is shown herein; rather, individual elements may be exaggerated for better understanding.

[0078] The attached diagram shows:

[0079] Figure 1 A schematic cross-sectional view of one embodiment of the optoelectronic semiconductor chip described herein is shown.

[0080] Figure 2 and 3 A schematic cross-sectional view showing a variation of a semiconductor chip;

[0081] Figure 4 and 5 A schematic cross-sectional view of an embodiment of the optoelectronic semiconductor chip described herein is shown;

[0082] Figure 6 A schematic curve showing the correlation between reflectivity and the thickness of the capping layer in a variant and embodiment of the optoelectronic semiconductor chip described herein is shown.

[0083] Figure 7 A schematic comparison diagram showing the reflectivity of different semiconductor chips is provided.

[0084] Figure 8 A through 8G illustrate schematic diagrams of the reflectivity of semiconductor chips, as a function of the incident angle, and as a function of the wavelength, in embodiments and variations thereof.

[0085] Figure 9 A schematic diagram illustrating the correlation between radiation intensity and radiation angle; and

[0086] Figures 10 to 14 A schematic cross-sectional view of an embodiment of the optoelectronic semiconductor chip described herein is shown. Detailed Implementation

[0087] exist Figure 1The following describes an embodiment of semiconductor chip 1. Semiconductor chip 1 includes a semiconductor layer sequence 2. In semiconductor chip 2, an active layer 23 is located between a p-type doped side 21 and an n-type doped side 22.

[0088] A mirror 3, having a wavelength L of maximum intensity, is present directly on the semiconductor layer sequence 2 for reflecting radiation generated in the active region 23 during operation. The mirror 3 includes a capping layer 31 directly adjacent to the semiconductor layer sequence 2. The capping layer 31 may be the thickest layer of the mirror 3. The capping layer 31 has a relatively low refractive index.

[0089] Along the direction away from the capping layer 31, the mirror 3 has a plurality of intermediate layers 32, 33. The intermediate layers 32, 33, together with the capping layer 31, preferably have alternating high and low refractive indices.

[0090] A metal layer 39 serves as a reflective layer, directly following the intermediate layers 32 and 33 in the direction away from the semiconductor layer sequence 2. The metal layer 39 is preferably made of gold, and alternatively, of silver.

[0091] The intermediate layers 32 and 33 of mirror 3, together with the cladding layer 31, form a modified Bragg mirror. Here, all intermediate layers 32 and 33 have an optical thickness different from L / 4, unlike in conventional Bragg mirrors. As a result, reduced spectral and angular dependence of reflectivity can be achieved.

[0092] The capping layer 31 is made of silicon dioxide, for example, and has a thickness of 520 nm. The first intermediate layer 32 is made of Nb₂O₅, for example, and has a thickness of 95 nm. The second intermediate layer 33 is made of silicon dioxide, for example, and has a thickness of 120 nm. At the wavelength L of maximum intensity at 616 nm and at room temperature, optical thicknesses of 0.35 and 0.28 L are obtained respectively for these layers, as shown in... Figure 1 As shown in the diagram. The cladding layer 31 has an optical thickness of 1.23L. The geometric thickness can be adjusted in relation to the wavelength L of maximum intensity.

[0093] The values ​​are applicable to optical thickness, and preferably have a maximum tolerance of 0.03L or 0.02L, especially in the intermediate layers 32 and 33.

[0094] exist Figure 2 The diagram shows a variant of a semiconductor chip 1'. Intermediate layers 32 and 33 are each L / 4 layers, i.e., layers with an optical thickness of L / 4, as in a conventional Bragg mirror. For example, there are 10.5 layer pairs, i.e., 21 layers. The first intermediate layer 32 is made of silicon dioxide, for example, while the second intermediate layer 33 is made of Nb5O2. Thus, a relatively large number of layers exist. Furthermore, in... Figure 2 The lack of such in Figure 1 The embodiment contains a thick covering layer.

[0095] exist Figure 3 In variant 1', there is a thick capping layer 31 and two layer pairs consisting of intermediate layers 32 and 33, each layer pair having an optical thickness of L / 4. Figure 3 The wavelength L, exemplarily representing the maximum intensity at 616 nm, illustrates the material and geometry layer thickness.

[0096] In an embodiment of semiconductor chip 1, as in Figure 4 As shown, there are three intermediate layers 32, 33, and 34, which follow the capping layer 31. The capping layer 31 has an optical thickness of approximately 1.22L. The optical thickness of the intermediate layers 32, 33, and 34 increases from the capping layer 31 toward the metal layer 39. Here, the difference in optical thickness between adjacent intermediate layers 32, 33, and 34 increases toward the metal layer 39.

[0097] exist Figure 5 In this embodiment, there are four intermediate layers 32, 33, 34, and 35. For three of these intermediate layers, the optical thickness increases in the direction away from the metal layer 39, starting at the metal layer 39. The intermediate layer 32, closest to the capping layer 31, has the second highest optical thickness. The intermediate layer 35, closest to the metal layer 39, is significantly thinner than L / 4.

[0098] exist Figure 4 and 5 The materials and thicknesses mentioned are for illustrative purposes only. All layers 31, 32, 33, 34, and 35 each have an optical thickness not equal to L / 4. The optical thicknesses of the intermediate layers 32, 33, 34, and 35 are as follows: Figure 4 and 5 As explained in the document, it can also be applied in slightly modified forms, for example, with tolerances each having a maximum of 0.04L or 0.02L.

[0099] exist Figure 6 The reflectance R is recorded as a percentage of the thickness T (in nm) relative to the cover layer T. Here, Figure 1 The embodiment of semiconductor chip 1 is compared with variant 1'. Variant 1', as in... Figure 6 As explained in the text, corresponding to Figure 3 The variant form 1', however, does not have intermediate layers 32 and 33.

[0100] from Figure 6 As can be seen, in the embodiment of semiconductor chip 1, the reflectivity R is reduced by an excessively thin cover layer 31 and a higher reflectivity R of approximately 0.4 percentage points is achieved compared to variant 1'.

[0101] exist Figure 7 In the middle, for such a combination Figure 6 The exposition and based on Figure 3 Variation 1' and Figure 2 Variant 1' and Figure 5 The reflectivity R of the semiconductor chip 1 in the embodiment is compared. It can be seen that, by means of... Figure 5 The construction of semiconductor chip 1 in the image can achieve a significantly improved reflectivity R. Reflectivity R, as in... Figure 7 As given in the paper, it involves reflectivity integrals over all angles.

[0102] exist Figure 8 For different embodiments and variations, A through 8F record the reflectivity R relative to the angle of incidence E in degrees and the wavelength λ in nm. The reflectivity R is encoded in... Figure 8 Described in G.

[0103] Figure 8 A relates to a variant 1', which has a mirror with a thick silicon dioxide layer and a gold layer directly beneath it, i.e., without the intermediate layers 32, 33. Figure 3 The structure.

[0104] exist Figure 8 Modification 1' is described in section B, which uses 10 layer pairs composed of silicon dioxide and Nb₂O₅, correspondingly 20 layers, with the bottom layer directly on a metal mirror composed of Nb₂O₅. Therefore, Figure 8 B's device corresponds to Figure 2 The variant 1', however, does not have the low-refractive-index intermediate layer 32 closest to the metal layer 39.

[0105] In such a state Figure 8 In variant form 1' described in C, there are 10.5 layer pairs, corresponding to 21 layers, as shown in... Figure 2 As explained in the text, a low-refractive-index layer exists directly on the metal mirror.

[0106] Figure 8 D shows that according to Figure 1 The reflectivity of the semiconductor chip 1 in this embodiment.

[0107] exist Figure 8 E explains Figure 5 The reflectivity R of the semiconductor chip 1 in this embodiment.

[0108] Finally, Figure 8 F describes Figure 3 The reflectivity R of variant form 1' in the model.

[0109] Especially from Figure 8 From D and 8E, we know that relatively high reflectivity R can be achieved up to a relatively small incident angle E, as in, for example, in Figure 8 The differences are found in B and 8C. Furthermore, a significantly smaller spectral correlation in reflectance R can be achieved, particularly at larger wavelengths above 600 nm.

[0110] Due to the strong modulation of reflectivity R, such as in Figure 8 As can be seen in B and 8C, a larger number of layers does not result in an overall increase in reflectivity. This is also evident from... Figure 7 As can be seen in the text.

[0111] exist Figure 9 The radiation intensity I is recorded normally relative to the radiation angle A. Here it is a variant form 1', as in... Figure 6 As described in the text, it is about to Figure 3 The configuration without intermediate layers 32 and 33 and Figure 1 A comparison of embodiments of semiconductor chip 1 is provided. The ideal Lambert emission characteristics are further illustrated.

[0112] from Figure 9 It can be seen that, over a large angular range, no deviation is visible between Example 1 and Variation 1'. Especially within the angular range of + / -70°, there is no significant deviation from the Lambertian emission characteristics. Intensity I particularly relates to the optical flow, which is averaged over all wavelengths.

[0113] exist Figure 10 In an embodiment of the semiconductor chip 1, a plurality of vias 5 are formed through layers 31, 32, and 33 of the mirror 3. The vias 5 are preferably metal vias. The semiconductor layer sequence 2 is electrically connected to the metal layer 39 of the mirror 3 via the vias 5. Thus, the metal layer 39 is part of the electrodes 6 used to power the semiconductor chip 1.

[0114] The via 5, when viewed in cross-section, is trapezoidal for example and may optionally narrow along the direction toward the semiconductor layer sequence 2. Alternatively, the via 5 may also be rectangular in cross-section.

[0115] exist Figure 11 In some embodiments, a contact layer 4 is additionally present. The contact layer 4 extends over the semiconductor layer sequence 2 and, in particular, completely covers each of the vias 5. The contact layer can be removed outside the vias 5.

[0116] The contact layer 4 is preferably made of a transparent conductive oxide, such as ITO. The thickness of the contact layer 4 is, for example, between 15 nm and 30 nm, and is preferably thin enough that the contact layer does not significantly affect the optical properties of the mirror 3 and / or the semiconductor chip 1. This contact layer 4 is also preferably... Figure 1 , 4The same applies to instances 5. If the contact layer 4 is made thicker and becomes optically effective, then the thicknesses of the cover layer 31 and intermediate layers 31, 32, 33, and 34 may be adjusted accordingly to achieve maximum reflectivity.

[0117] exist Figure 12 The description states that the capping layer 31 and intermediate layers 32, 33, and 34 extend across the entire surface of the metal layer 39. Layers 31, 32, 33, and 34 are preferably made of a conductive material, such as a transparent conductive oxide. This eliminates the need for... Figure 10 and 11 The through-holes exist in the middle. Contact layer 4 can also be omitted.

[0118] One of the electrodes 6 is located on the optocoupler output side 10 and can be connected to a current extension structure (not shown). The metal layer 39 of the mirror 3 can be located on the electrode 6 of the carrier 7. External electrical contact can optionally be achieved via the region of the electrode 6 adjacent to the semiconductor layer sequence 2, for example via bonding wires. The electrode 6 on the optocoupler output side 10 can also be contacted, for example, via bonding wires. If the carrier 7 is conductive, then bonding wire-free contact can be achieved from the side having the metal layer 39.

[0119] The other electrode 6 on the optically coupled output side 10 is... Figure 10 and 11 Neither of these points are explained. Figures 10 to 12 Depending on the diagram, a flip-chip configuration is also possible.

[0120] exist Figure 13 In embodiments A to 13C, an additional attachment layer 8 is provided, each located between the metal layer 39 and an intermediate layer directly abutting the metal layer 39. The attachment layer 8 is determined according to... Figure 13 B extends continuously on the metal layer 39 and also completely covers the through-hole 5, such that the through-hole 5 is covered by the reinforcement layer 8. And... Figure 13 In A, the attached layer 8 is confined to the boundary between the metal layer 39 and the nearest intermediate layer 32.

[0121] In addition, Figure 13 As shown in section B, a contact layer 4 exists in addition to the adhesion layer 8. The adhesion layer 8 and the contact layer 4 may be made of the same material or different materials.

[0122] exist Figure 13 In C, an additional layer 8 is formed, such as in Figure 13 As explained in section A, an additional contact layer 4 exists.

[0123] The reinforcement layer 8 is preferably made of a transparent conductive oxide, such as ITO. The thickness of the reinforcement layer 8 is, for example, between 1 nm and 20 nm, and is preferably thin enough that the reinforcement layer 8 is optically ineffective and has no or no significant effect on the optical properties of the mirror 3 and / or the semiconductor chip 1.

[0124] As in Figure 13 The attachment layer 8 shown in A to 13C is preferably also present in all other embodiments.

[0125] exist Figure 14 As shown in A and 14B, the semiconductor layer sequence 2 of the semiconductor chip 1 is structured. The via 5 is preferably located in a region of the semiconductor layer sequence 2 that is thicker than the rest of the region. This structure of the semiconductor layer sequence 2 prevents the active region 23 from being directly energized below the electrode 6. The electrode 6, directly on the semiconductor layer sequence 2, is formed, for example, by a current distribution patch. Furthermore, this structured portion improves the optical coupling output efficiency because light redirection can be performed on the structured portion. The capping layer 31, the intermediate layers 32 and 33, and the metal layer 39 conform to the shape of the semiconductor layer sequence 2. That is, the mirror 3 extends planarly on the semiconductor layer sequence 2, but is not formed flatly; rather, it depicts the topography of the semiconductor layer sequence 2.

[0126] exist Figure 14 As shown in section B, a contact layer 4 is additionally present. The contact layer 4 is applied only locally here, starting from at least one associated through-hole 5. Figure 14 The diagram for B is different. Since the lateral conductivity of the first side 21 of semiconductor layer sequence 2 is small, the location of the active region 23 can be determined. Therefore, the structuring of semiconductor layer sequence 2 itself is not required.

[0127] Unless otherwise stated, the components shown in the figures are preferably arranged directly next to each other in the given order. Layers that do not touch in the figures are preferably spaced apart from each other. Where lines are shown parallel to each other, the corresponding surfaces are preferably also oriented parallel to each other. Likewise, unless otherwise stated, the relative positions of the components shown are correctly depicted in the figures.

[0128] The invention described herein is not limited to the description based on the embodiments. Rather, the invention includes any new features and any combination of features, particularly any combination of features in the claims, even if the features or combinations are not described in detail in the claims or embodiments.

[0129] This application claims priority to German patent applications 10 2018 106 001.7 and 10 2018 107 667.3, the disclosures of which are incorporated herein by reference.

[0130] According to embodiments of this disclosure, the following notes are also disclosed:

[0131] 1. A photoelectronic semiconductor chip (1), the photoelectronic semiconductor chip having:

[0132] - A semiconductor layer sequence (2), the semiconductor layer sequence having an active region (23) for generating radiation of wavelength L with maximum intensity; and

[0133] - A mirror (3) for radiation on the back side (12), which is opposite to the optically coupled output side (10).

[0134] in

[0135] - The mirror (3) includes a capping layer (31) that is closest to the semiconductor layer sequence (2).

[0136] - The covering layer (31) is made of a material permeable to the radiation and has an optical thickness between 0.5L and 3L, including boundary values.

[0137] -A series of intermediate layers (32, 33, 34, 35) following the capping layer (31) in a direction opposite to the semiconductor layer sequence (2), containing boundary values,

[0138] The intermediate layers (32, 33, 34, 35) alternately have high and low refractive indices for the radiation and are each made of a material permeable to the radiation.

[0139] - At least one metal layer (39) follows the intermediate layer (32, 33, 34, 35) as a reflective layer in a direction opposite to the semiconductor layer sequence (2), and

[0140] - The high-refractive-index intermediate layers (33) each have an optical thickness between 0.3L and 0.4L, including boundary values, and the low-refractive-index intermediate layers (32) located therebetween each have an optical thickness between 0.26L and 0.35L, including boundary values.

[0141] 2. The optoelectronic semiconductor chip (1) described in the preceding note,

[0142] A contact layer (4) composed of transparent conductive oxide exists directly between the cover layer (31) and the semiconductor layer sequence (2).

[0143] The contact layer (4) has a thickness between 2 nm and 300 nm, including boundary values.

[0144] 3. The optoelectronic semiconductor chip (1) according to any one of the above appendices,

[0145] The mirror (3) comprises exactly three or exactly four of the intermediate layers (31, 32).

[0146] The intermediate layers (32, 33) each have an optical thickness of L / 3 and a tolerance of up to 0.06L.

[0147] 4. The optoelectronic semiconductor chip (1) according to any one of the above appendices,

[0148] The cover layer (31) has an optical thickness between 0.9L and 1.6L, including boundary values.

[0149] 5. The optoelectronic semiconductor chip (1) according to any one of the foregoing notes,

[0150] The total optical thickness of the capping layer (31) together with all the intermediate layers (32, 33, 34, 35) is between 1.6L and 2.7L, including boundary values.

[0151] The cover layer (31) and the intermediate layers (32, 33, 34, 35) are constructed of exactly two different materials.

[0152] 6. The optoelectronic semiconductor chip (1) according to any one of the foregoing notes,

[0153] The cover layer (31), the intermediate layers (32, 33, 34, 35), and the metal layer (39) follow each other directly and planarly.

[0154] At least the cover layer (31) and the intermediate layers (32, 33, 34, 35) are layers with a constant thickness and extend overlapping each other.

[0155] 7. The optoelectronic semiconductor chip (1) according to any one of the foregoing notes,

[0156] The capping layer (31) is composed of SiO2 and the intermediate layers (32, 33, 34, 35) are alternately composed of Nb2O5 and SiO2.

[0157] The metal layer (39) is made of gold or silver.

[0158] 8. The optoelectronic semiconductor chip (1) according to any one of the foregoing notes,

[0159] The metal layer (39) is ohmically conductively connected to or is part of the electrode (6) of the semiconductor chip (1).

[0160] 9. The optoelectronic semiconductor chip (1) according to any one of the foregoing notes,

[0161] The mirror (3) is located on the p-type doped side (21) of the semiconductor layer sequence (2).

[0162] A plurality of vias (5) for electrical contact with the p-type doped side (21) extend through the mirror (3).

[0163] 10. The optoelectronic semiconductor chip (1) described in the preceding note,

[0164] The through-holes (5) are all metallic and penetrate the cover layer (31) and all intermediate layers (32, 33, 34, 35), and

[0165] The aforementioned reinforcement layer (8) is located directly between the metal layer (39) and the intermediate layers (32, 33, 34) closest to the metal layer (39).

[0166] 11. The optoelectronic semiconductor chip (1) described in accordance with Appendix 2 and one of the preceding two appendices,

[0167] The contact layer (4) and / or the adhesion layer (8) extend continuously over all the through holes (5).

[0168] 12. The optoelectronic semiconductor chip (1) according to Appendix 2 and according to Appendix 9 or 10,

[0169] The contact layer (4) extends only partially over the semiconductor layer sequence (2) from the via (5) such that the contact layer (4) is completely or partially removed from the region adjacent to the via (5).

[0170] 13. The optoelectronic semiconductor chip (1) according to any one of the foregoing notes,

[0171] The semiconductor layer sequence (2) is based on AlInGaAs or InGaAlP and the wavelength L of the maximum intensity is between 570 nm and 950 nm, including boundary values.

[0172] 14. A photoelectronic semiconductor chip (1), said photoelectronic semiconductor chip having:

[0173] - A semiconductor layer sequence (2), the semiconductor layer sequence having an active region (23) for generating radiation of wavelength L with maximum intensity; and

[0174] - A mirror (3) for radiation on the back side (12), which is opposite to the optically coupled output side (10).

[0175] in

[0176] - The mirror (3) includes a capping layer (31) that is closest to the semiconductor layer sequence (2).

[0177] - The covering layer (31) is made of a material permeable to the radiation and has an optical thickness between 0.5L and 3L, including boundary values.

[0178] -A series of intermediate layers (32, 33, 34, 35) following the capping layer (31) in a direction opposite to the semiconductor layer sequence (2), containing boundary values,

[0179] The intermediate layers (32, 33, 34, 35) alternately have high and low refractive indices for the radiation and are each made of a material permeable to the radiation.

[0180] - The thickness of at least one of the intermediate layers (32, 33, 34, 35) is not equal to L / 4, and

[0181] - At least one metal layer (39) is followed as a reflective layer after the intermediate layer (32, 33, 34, 35) in a direction opposite to the semiconductor layer sequence (2).

[0182] 15. The optoelectronic semiconductor chip (1) described in the preceding note,

[0183] At least 50% of the intermediate layers (32, 33, 34, 35) have an optical thickness of L / 3, with a maximum tolerance of L / 15.

[0184] The low-refractive-index capping layer (31) and all intermediate layers (32, 33, 34, 35) are each composed of oxides, nitrides or oxynitrides and are each dielectric.

[0185] 16. The optoelectronic semiconductor chip (1) according to Appendix 14,

[0186] The mirror (3) has at most two intermediate layers (32, 33, 34, 35) with an optical thickness of (L / 4+N / 2)+ / -L / 20, where N is a natural number greater than or equal to zero.

[0187] 17. The optoelectronic semiconductor chip (1) according to Appendix 14,

[0188] The optical thickness of at least three of the intermediate layers (32, 33, 34, 35) increases in a direction away from the cover layer (31).

[0189] The difference in optical thickness between these adjacent intermediate layers (32, 33, 34, 35) lies between 0.03L and 0.15L, including boundary values.

[0190] 18. The optoelectronic semiconductor chip (1) according to Appendix 14,

[0191] The optical thickness of at least three of the intermediate layers (32, 33, 34, 35) increases in a direction away from the metal layer (39).

[0192] The difference in optical thickness between these adjacent intermediate layers (32, 33, 34, 35) lies between 0.09L and 0.14L, including boundary values.

[0193] 19. The optoelectronic semiconductor chip (1) according to Appendix 14,

[0194] The optical thickness of one of the intermediate layers (32, 33, 34, 35) is up to L / 5.

[0195] These intermediate layers (32, 33, 34, 35) are closer to the metal layer (39) than the cover layer (31).

[0196] 20. The optoelectronic semiconductor chip (1) according to Appendix 14,

[0197] The intermediate layers (32, 33, 34, 35) closest to the metal layer (39) have an optical thickness between 0.28L and 0.45L, including boundary values, or an optical thickness between 0.78L and 0.95L, including boundary values.

[0198] At least 50% of the remaining intermediate layers (32, 33, 34, 35) have an optical thickness between 0.255L and 0.45L, including boundary values, or have an optical thickness between 0.755L and 0.95L, including boundary values, and

[0199] The intermediate layers (32, 33, 34, 35) closest to the metal layer (39) are high-refractive-index layers.

[0200] List of reference numerals

[0201] 1. Optoelectronic semiconductor chip

[0202] 1' Variations of semiconductor chips

[0203] 10 Optical Coupler Output Side

[0204] 12 Dorsal side

[0205] 2 Semiconductor layer sequence

[0206] 21 p-type doped side

[0207] 22 n-type doped side

[0208] 23 Active Zone

[0209] 3 mirrors

[0210] 31 Covering layer

[0211] 32 First Intermediate Layer

[0212] 33 Second Intermediate Layer

[0213] 34 Other intermediate layers

[0214] 35 Intermediate Layer

[0215] 39 Metal Layer

[0216] 4. Contact layer

[0217] 5 power through holes

[0218] 6 electrodes

[0219] 7. Bearing components

[0220] 8. Additive Layer

[0221] A. Radiation angle in degrees

[0222] E is the angle of incidence in degrees.

[0223] I Intensity

[0224] L is the wavelength of maximum intensity.

[0225] R is the reflectance in percentage.

[0226] T thickness of the cover layer

[0227] λ is the wavelength in nm.

Claims

1. An optoelectronic semiconductor chip (1) having: - a semiconductor layer sequence (2) having an active region (23) for generating radiation having a wavelength L of maximum intensity; and - a mirror (3) for the radiation on a back side (12) which is opposite a light- coupling-out side (10), and - at least one via (5) for electrical contacting, wherein - the mirror (3) comprises a cover layer (31), - the cover layer (31) consists of a material which is transparent to the radiation and has an optical thickness of at least 0.5 L, - a plurality of intermediate layers (32, 33, 34, 35) follow the cover layer (31) in the direction away from the semiconductor layer sequence (2), - the intermediate layers (32, 33, 34, 35) alternately have a high and a low refractive index for the radiation and each consist of a material which is transparent to the radiation, - at least one metal layer (39) as a reflection layer follows the intermediate layers (32, 33, 34, 35) in the direction away from the semiconductor layer sequence (2), and an adhesion-promoting layer (8) is located directly between the intermediate layers (32, 33, 34, 35) and the metal layer (39), and - the adhesion-promoting layer (8) completely covers the via (5) such that the adhesion-promoting layer (8) coats the via (5).

2. The optoelectronic semiconductor chip (1) according to the preceding claim, wherein a contact layer (4) consisting of a transparent conductive oxide is present directly between the cover layer (31) and the semiconductor layer sequence (2), wherein the contact layer (4) has a thickness of between 2 nm and 300 nm, inclusive.

3. The optoelectronic semiconductor chip (1) according to claim 1 or 2, wherein the mirror (3) comprises exactly three or exactly four intermediate layers (31, 32), wherein the intermediate layers (32, 33) each have an optical thickness of L / 3, with a tolerance of at most 0.06 L.

4. The optoelectronic semiconductor chip (1) according to claim 1 or 2, wherein the cover layer (31) has an optical thickness of between 0.9 L and 1.6 L, inclusive.

5. The optoelectronic semiconductor chip (1) according to claim 1 or 2, wherein the optical total thickness of the cover layer (31) together with all intermediate layers (32, 33, 34, 35) lies between 1.6 L and 2.7 L, inclusive, wherein the cover layer (31) and the intermediate layers (32, 33, 34, 35) are constructed in total from exactly two different materials.

6. The optoelectronic semiconductor chip (1) according to claim 1 or 2, wherein the cover layer (31), the intermediate layers (32, 33, 34, 35) and the metal layer (39) follow one another directly and planarly, wherein at least the cover layer (31) and the intermediate layers (32, 33, 34, 35) are each layers having a constant thickness and extend congruently with one another.

7. The optoelectronic semiconductor chip (1) according to claim 1 or 2, wherein the cover layer (31) consists of SiO2 and the intermediate layers (32, 33, 34, 35) alternately consist of Nb2O5 and SiO2, wherein the metal layer (39) consists of gold or silver.

8. The optoelectronic semiconductor chip (1) according to claim 1 or 2, wherein the metal layer (39) is ohmically conductively connected with an electrode (6) of the semiconductor chip (1) or is part of an electrode (6).

9. The optoelectronic semiconductor chip (1) according to claim 1 or 2, wherein the mirror (3) is located on a p-doped side (21) of the semiconductor layer sequence (2), wherein a plurality of electrical vias (5) for electrically contacting the p-doped side (21) extend through the mirror (3).

10. The optoelectronic semiconductor chip (1) according to claim 1 or 2, wherein the vias (5) are metallic and penetrate the cover layer (31) and all intermediate layers (32, 33, 34, 35).

11. The optoelectronic semiconductor chip (1) according to claim 2, wherein the contact layer (4) and / or the adhesion-promoting layer (8) continuously extends over all vias (5).

12. The optoelectronic semiconductor chip (1) according to claim 2, wherein the contact layer (4) extends only partially over the semiconductor layer sequence (2) starting from the vias (5) such that the contact layer (4) is completely or partially removed from the area next to the vias (5).

13. The optoelectronic semiconductor chip (1) according to claim 1 or 2, wherein at least 50% of the intermediate layers (32, 33, 34, 35) have an optical thickness of L / 3 with a tolerance of up to L / 15, wherein the cover layer (31) and all intermediate layers (32, 33, 34, 35) each consist of an oxide, nitride or oxynitride and are each dielectric.

14. The optoelectronic semiconductor chip (1) according to claim 1 or 2, wherein the mirror (3) has at most two intermediate layers (32, 33, 34, 35) having an optical thickness of (L / 4+N / 2)+ / -L / 20, where N is a natural number greater than or equal to zero.

15. The optoelectronic semiconductor chip (1) according to claim 1 or 2, wherein the optical thickness of at least three of the intermediate layers (32, 33, 34, 35) increases in a direction away from the cover layer (31), wherein the difference in optical thickness between adjacent ones of these intermediate layers (32, 33, 34, 35) lies between 0.03L and 0.15L, inclusive.

16. The optoelectronic semiconductor chip (1) according to claim 1 or 2, wherein the optical thickness of at least three of the intermediate layers (32, 33, 34, 35) increases in a direction away from the metal layer (39), wherein the difference in optical thickness between adjacent ones of the intermediate layers (32, 33, 34, 35) lies between 0.09L and 0.14L, inclusive.

17. The optoelectronic semiconductor chip (1) according to claim 1 or 2, wherein the optical thickness of one of the intermediate layers (32, 33, 34, 35) is at most L / 5, wherein the intermediate layers (32, 33, 34, 35) are closer to the metal layer (39) than the cover layer (31).

18. The optoelectronic semiconductor chip (1) according to claim 14, wherein the intermediate layer (32, 33, 34, 35) closest to the metal layer (39) has an optical thickness between 0.28L and 0.45L, inclusive, or an optical thickness between 0.78L and 0.95L, inclusive, wherein at least 50% of the remaining intermediate layers (32, 33, 34, 35) have an optical thickness between 0.255L and 0.45L, inclusive, or an optical thickness between 0.755L and 0.95L, inclusive, and wherein the intermediate layer (32, 33, 34, 35) closest to the metal layer (39) is a high refractive index layer.

19. The optoelectronic semiconductor chip (1) according to claim 2, wherein - the via (5) extends from the metal layer (39) to the contact layer (4) and electrically conductively connects the metal layer (39) and the contact layer (4) to each other, and - the via (5) and the contact layer (4) comprise the same material.

20. The optoelectronic semiconductor chip (1) according to claim 2, wherein the adhesion-promoting layer (8) is provided between the metal layer (39) and the intermediate layers (32, 33, 34, 35), between the via (5) and the intermediate layers (32, 33, 34, 35), and between the via (5) and the contact layer (4).

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