Optoelectronic semiconductor device and method for operating an optoelectronic semiconductor device

Abstract

An optoelectronic semiconductor component (1) is described, comprising an optoelectronic semiconductor chip (2) and a package (3) comprising a matrix material (31), wherein the semiconductor chip is embedded in the package, and wherein the package is designed such that a cavity (5) is formed during operation of the optoelectronic semiconductor component, which cavity is completely arranged within the package. Furthermore, a method for operating a semiconductor component is described.

Description

Technical Field

[0001] An optoelectronic semiconductor component and a method for operating an optoelectronic semiconductor component are specified. Background Art

[0002] Optoelectronic semiconductor devices, such as light-emitting diodes (LEDs), are often embedded in packages. When silicone resin is used for the package, shrinkage due to aging has been shown to cause the package to peel away from the semiconductor chip and / or the leadframe of the semiconductor device. This can impair the corrosion resistance and brightness of the semiconductor device. Summary of the Invention

[0003] The object is to specify a semiconductor component which has good optoelectronic properties and at the same time good aging properties.

[0004] This object is achieved in particular by an optoelectronic semiconductor component or an operating method according to the independent claims. Further refinements and expediencies are the subject matter of the dependent claims.

[0005] An optoelectronic semiconductor component having at least one optoelectronic semiconductor chip is described. The optoelectronic semiconductor component may also have more than one optoelectronic semiconductor chip. The optoelectronic semiconductor chip is configured to generate and / or receive radiation, for example, radiation in the ultraviolet, visible, or infrared spectral range.

[0006] For example, the semiconductor chip, in particular the active region of the semiconductor chip, comprises a III-V compound semiconductor material. III-V compound semiconductor materials are particularly suitable for ultraviolet spectral range (Al x In y Ga 1-x-y N) via the visible spectral range (Al x In y Ga 1-x-y N, especially for blue to green radiation, or Al x In y Ga 1-x-y P, especially for yellow to red radiation) to the infrared spectral range (Al x In y Ga 1-x-y As). In this case, 0 x 1, 0 y 1 and x+y 1, especially where x 1.y 1.x 0 and / or y 0. Furthermore, the use of III-V compound semiconductor materials, in particular from the material systems mentioned, makes it possible to achieve high internal quantum efficiencies in the generation of radiation.

[0007] According to at least one embodiment of the optoelectronic semiconductor component, the optoelectronic semiconductor component comprises a package in which the semiconductor chip is embedded, the package for example directly adjoining the optoelectronic semiconductor chip in places.

[0008] The package is produced, for example, by a casting method. A casting method is generally understood to be a method in which a molding compound can be configured to a predetermined shape and, if necessary, cured. The term "casting method" specifically includes casting, film-assisted molding, injection molding, transfer molding, and compression molding.

[0009] According to at least one embodiment of the optoelectronic semiconductor component, the encapsulation comprises a matrix material which is expediently transmissive to radiation generated and / or received by the optoelectronic semiconductor chip during operation.

[0010] In particular, the transparent matrix material can be, for example, silicones, epoxies, acrylates, methyl methacrylates, imides, carbonates, olefins, styrenes, urethanes, or their derivatives in monomeric form, oligomers, or polymers, and can also comprise mixtures, copolymers, or compounds. For example, the matrix material can include or be epoxy resins, polymethyl methacrylate (PMMA), polystyrene, polycarbonates, polyacrylates, polyurethanes, silicone resins, or silicone resins such as polysiloxanes, or mixtures thereof.

[0011] In accordance with at least one embodiment of the optoelectronic semiconductor component, the matrix material comprises or consists of silicone.

[0012] According to at least one embodiment of the optoelectronic semiconductor device, the package is designed such that cavities are formed during operation of the optoelectronic semiconductor device. The cavities are arranged completely within the package. In particular, the cavities are not generated until operation of the optoelectronic semiconductor device. Consequently, immediately after manufacturing the optoelectronic semiconductor device, no cavities are present in the package. In particular, the number of cavities can increase as the operating duration of the optoelectronic semiconductor device increases, at least during a specific operating period.

[0013] In at least one embodiment of an optoelectronic semiconductor component, the optoelectronic semiconductor component comprises an optoelectronic semiconductor chip and a package comprising a matrix material, wherein the semiconductor chip is embedded in the package, and wherein the package is designed such that a cavity arranged completely within the package is formed during operation of the optoelectronic semiconductor component.

[0014] The package is therefore specifically designed so that a cavity is created in the package during operation of the semiconductor device. This cavity is completely surrounded by the encapsulation material and does not extend to the outer surface of the package. In other words, the cavity does not form a path through which, for example, air and / or moisture could reach the semiconductor chip.

[0015] The outer surface of the package is, for example, the interface between the package and other parts of the semiconductor device, such as the interface with the semiconductor chip and / or with the housing and / or with the lead frame of the housing. In addition, the outer surface of the package may partially enclose the semiconductor device. This means that the outer surface of the package is also partially the outer surface of the semiconductor device.

[0016] It has been shown that such a closed cavity leads to reduced peeling forces that could cause the package to detach from the semiconductor chip or other parts of the semiconductor device. In other words, the cavity leads to reduced stress in the package and reduced peeling forces.

[0017] According to at least one embodiment of the optoelectronic semiconductor component, the encapsulation is designed such that aging-induced shrinkage of the matrix material leads to the formation of a cavity. In particular, the material composition of the encapsulation is designed such that the cavity is generated during operation of the optoelectronic semiconductor component.

[0018] This ensures that the package remains adhered to the semiconductor chip and / or other parts of the optoelectronic semiconductor component adjoining the package, even if the matrix material shrinks due to aging. The risk of crack formation at the interface between the package and the semiconductor chip and / or other parts of the semiconductor component is avoided or at least reduced.

[0019] According to at least one embodiment of the optoelectronic semiconductor component, particles are introduced into the matrix material of the encapsulation as crack nuclei, so that cavities form at least at some of the crack nuclei during operation of the optoelectronic semiconductor component. The particles thus serve as starting points for the formation of cavities, for example in the form of microcracks. For example, the cavities have an extent of at most 100 μm or at most 50 μm along the direction of maximum extent. Alternatively or additionally, the cavities have an extent of at least 5 μm or at least 10 μm along the direction of maximum extent.

[0020] According to at least one embodiment of the optoelectronic semiconductor component, the particles are transmissive to radiation to be generated and / or received by the optoelectronic semiconductor chip. In particular, the particles do not absorb the radiation or absorb it at least only to a negligible extent.

[0021] According to at least one embodiment of the optoelectronic semiconductor component, the particles are optically inert. This means, in particular, that the particles are not intended to shape the spatial and / or spectral emission characteristics of the optoelectronic semiconductor component. In particular, the particles are neither diffusers nor luminescent substances. In other words, a package containing such particles has essentially the same optical properties as a package without such particles.

[0022] According to at least one embodiment of the optoelectronic semiconductor component, the particles consist of a material whose refractive index is adapted to the refractive index of the matrix material. Preferably, the refractive index of the particle material differs from that of the matrix material by at most 10%, particularly preferably by at most 5%. The smaller the difference in refractive index between the particle material and the matrix material, the smaller optical interface effects, such as refractive effects, are.

[0023] For the avoidance of doubt, these refractive indices each relate to the refractive index of the material at room temperature.

[0024] According to at least one embodiment of the optoelectronic semiconductor component, at least some of the particles have an angular basic shape. Consequently, the particles are not completely rotationally symmetrical. It has been shown that the edges of the particles act particularly effectively as crack nuclei. For example, the maximum extent of at least some of the particles in one direction is at least 10% greater than the diameter of an ideally spherical particle of the same volume.

[0025] According to at least one embodiment of the optoelectronic semiconductor component, the particles have an average diameter of between 5 μm and 30 μm, both inclusive. In the case of non-spherical particles, the maximum extension is considered to be the diameter. The particle diameter is therefore larger than the wavelength of the maximum intensity of the radiation to be generated and / or received.

[0026] According to at least one embodiment of the optoelectronic semiconductor component, the particles are present in the encapsulation in a proportion of between 3% and 30% by weight, in particular between 5% and 25% by weight, all values ​​inclusive. If the proportion of particles is too low, cavities cannot be created in the encapsulation with a sufficient density. If the proportion is too high, the particles cause an excessive increase in the viscosity of the encapsulation material, thereby making processing more difficult during the production of the optoelectronic semiconductor component.

[0027] According to at least one embodiment of the optoelectronic semiconductor component, the matrix material is a silicone. The matrix material is preferably a so-called high-refractive-index silicone, with a refractive index between 1.52 and 1.6, in particular between 1.54 and 1.56, inclusive.

[0028] The use of a highly refractive silicone resin reduces the difference in refractive index between the optoelectronic semiconductor chip and the package. This improves the optical coupling between the optoelectronic semiconductor chip and the package. Consequently, when the optoelectronic semiconductor chip generates radiation, the outcoupling efficiency is improved.

[0029] However, in principle, high-refractive-index silicones exhibit a greater tendency to delaminate than low-refractive-index silicones.

[0030] However, with the package configuration described in the present case, it is also possible to reliably construct the package based on a high-refractive-index silicone as the matrix material, thereby achieving high aging stability. Thus, a high level of aging stability can be combined with good optical coupling of the semiconductor chip to the package.

[0031] In principle, however, silicones with a low refractive index can also be used, for example silicones with a refractive index between 1.4 and 1.5, in particular between 1.45 and 1.48, inclusive.

[0032] According to at least one embodiment of the optoelectronic semiconductor component, the refractive index of the matrix material is between 1.4 and 1.6 inclusive. For example, the matrix material comprises a polymer material or a hybrid material.

[0033] According to at least one embodiment of the optoelectronic semiconductor component, the encapsulation includes a luminescent substance in addition to the particles. The luminescent substance is provided for fully or partially converting the primary radiation generated by the optoelectronic semiconductor chip into secondary radiation having a wavelength range that at least partially differs from the primary radiation. For example, the primary radiation lies in the blue or ultraviolet spectral range, while the secondary radiation lies in the red, yellow, green, or blue spectral range. For example, the optoelectronic semiconductor component emits mixed light that appears white to the human eye.

[0034] The luminescent material can comprise one or more of the following materials: garnets of rare earth and alkaline earth metals, such as YAG:Ce3+, nitrides, nitrided silicates, Sione, Sialon, aluminates, oxides, halophosphates, orthosilicates, sulfides, vanadates, and chlorosilicates. Furthermore, the luminescent material can additionally or alternatively comprise an organic material, which can be selected from the group consisting of perylene, benzopyrene, coumarin, rhodamine, and azo pigments. The package can comprise a suitable mixture and / or combination of the aforementioned luminescent materials. Thus, for example, as described above, the package can absorb in a first blue wavelength range and emit in a second wavelength range consisting of green and red wavelengths and / or a yellow wavelength range.

[0035] Furthermore, a method for operating an optoelectronic semiconductor component is specified.

[0036] According to at least one embodiment of a method for operating an optoelectronic semiconductor component, an optoelectronic semiconductor component is provided, comprising an optoelectronic semiconductor chip and a package comprising a matrix material, wherein the semiconductor chip is embedded in the package. The optoelectronic semiconductor component is operated such that a cavity is formed that is completely disposed within the package.

[0037] The optoelectronic semiconductor device is thus operated in a targeted manner such that the cavity is formed in the package. This is advantageously performed during normal operation of the optoelectronic semiconductor device. Therefore, no separate manufacturing steps or additional operating modes are necessary for this purpose. Formation of the cavity can avoid or at least reduce the risk of package delamination during operation, and in particular, does not reduce the power consumption of the optoelectronic semiconductor device, at least on average.

[0038] An optoelectronic semiconductor component having one or more features of the optoelectronic semiconductor component described above is particularly suitable for the operating method. Features described in conjunction with the optoelectronic semiconductor component can therefore also be used for the operating method, and vice versa.

[0039] Further details and schematics are given in the following description of exemplary embodiments in conjunction with the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1A and Figure 1B Based on after manufacturing ( Figure 1A ) and after a predetermined operating time ( Figure 1B ) shows an embodiment of a semiconductor device and a method for operating the semiconductor device;

[0041] Figure 2A shows a scanning electron micrograph of a reference sample with a peeled reference package;

[0042] Figure 2B shows a scanning electron micrograph of a cross section of the above semiconductor device having a package with a cavity;

[0043] Figure 3A and 3B The normalized luminous flux L measured for the semiconductor device and the reference sample according to the operating duration t in hours is shown. N The measurement result expressed as a percentage of Figure 3A Normalized to the luminous flux at time t=0 (also called lumen maintenance / ),exist Figure 3B where is the change in chromaticity coordinates expressed in pts relative to time t=0 (also called color shift) ;

[0044] Figure 4A and Figure 4B The following are shown when assuming there are 6 cavities ( Figure 4A ) and with 18 cavities ( Figure 4B ) package in the case of the simulation results of peel stress.

[0045] Elements that are identical, of the same type or have the same function are provided with the same reference symbols in the figures.

[0046] The figures are schematic and therefore not necessarily drawn to scale. Rather, relatively small elements and, in particular, layer thicknesses may be shown exaggerated for the sake of clarity. DETAILED DESCRIPTION

[0047] according to Figure 1A The optoelectronic semiconductor component of the exemplary embodiment shown in FIG has an optoelectronic semiconductor chip 2 , which is embodied as an LED semiconductor chip, for example. The optoelectronic semiconductor chip 2 is embedded in a package 3 .

[0048] In the exemplary embodiment shown, the semiconductor chip 2 is located in the cavity of the housing 6 and can be electrically contacted from the outside via a lead frame 61. However, the described design of the package 3 is generally applicable to any type of housing in which an optoelectronic semiconductor chip is embedded in a package 3 that is particularly radiation-transmissive.

[0049] The package 3 is designed such that during operation of the optoelectronic semiconductor component a cavity 5 is formed which is arranged completely within the package 3 . Figure 1B The semiconductor component 1 is therefore operated in a targeted manner such that cavities 5 are formed in the package 3 , in particular in the form of microcracks.

[0050] The cavity 5 can be used to reduce stresses that could cause the package 3 to peel off from the semiconductor chip 2 or parts of the housing 6 (eg, the lead frame 61 ).

[0051] This from Figure 2A and Figure 2B As is clear from the scanning electron micrograph shown, in the case of a conventional reference package 39, shrinkage of the reference package due to aging may result in the reference package 39 being partially detached from the semiconductor chip 2. This can be seen in the Figure 2A The position pointed by the arrow 91 is seen.

[0052] In contrast, package 3 consists of Figure 2B The cavity 5 pointed to by the arrow 95 in FIG. 8 results in a firmly fixed connection between the package 3 and the semiconductor chip 2 and the housing 6 .

[0053] A gap between the package 3 and the semiconductor chip 2 may reduce the brightness of the radiation emitted by the optoelectronic semiconductor component 1 , for example due to corrosion effects. Such a gap may also impair the optical coupling of the optoelectronic semiconductor chip 2 to the package 3 , which likewise leads to a reduction in brightness.

[0054] Furthermore, this may also cause a shift in the color coordinates of the radiation emitted by the semiconductor device as a whole. Figure 3A and Figure 3B The measurement shows that the brightness drop of the semiconductor device with the above package (shown by curve 7) is significantly lower than the brightness drop of reference curve 8. For reference curve 8, the change in chromaticity coordinates is also significantly greater, as shown in FIG. Figure 3B shown.

[0055] Figure 4A and Figure 4B The simulation results for the resulting peel stress are shown. This is based on a package with a cross-section of 150 μm x 250 μm. Furthermore, an aging-induced shrinkage of 4.5% was assumed for package 3. For a conventional, uniform package, i.e., a reference package without a cavity, this results in a peel stress of 0.154 MPa.

[0056] Figure 4A and Figure 4B shows a simulation in which six cavities are assumed ( Figure 4A ) and 18 cavities ( Figure 4B ) rather than a uniform conventional package, where each cavity has a length of 20 μm. Simulation results show that with six cavities, the peel stress is reduced by 0.139 MPa, while with 18 cavities, the peel stress is reduced by 0.109 MPa. These simulations demonstrate that cavities have a positive effect on peel stress, thereby generally improving the aging stability of semiconductor device 1.

[0057] For example, a matrix material 31 comprising or consisting of silicone is suitable for the encapsulation 3. Silicones with a high refractive index, for example between 1.54 and 1.56, are particularly suitable. However, in principle, the other matrix materials mentioned in the description can also be used.

[0058] Particles 4 can be introduced into the matrix material 31 of the package, which act as crack nuclei and promote the formation of cavities in the package. In principle, any material that is transparent to the radiation to be generated or received by the optoelectronic semiconductor chip is suitable for these particles. The particles 4 preferably consist of a material whose refractive index does not differ from that of the matrix material 31, or differs only slightly. The refractive indices preferably differ by at most 10%, particularly preferably by at most 5%. For example, the particles contain an oxide, such as silicon dioxide.

[0059] Alternatively, acrylates such as polymethyl methacrylate (PMMA), imides such as polymethacryloylmethylimide (PMMI), or glass are suitable for the particles.

[0060] The particles 4 preferably have an average diameter comprised between 5 μm and 30 μm, both limits included.

[0061] Furthermore, it has been shown that particles 4 having an angular basic shape act particularly effectively as crack nuclei for forming cavities 5 in the encapsulation 3. However, spherical particles can also be used in principle.

[0062] The particles 4 are preferably present in a proportion of at least 3% by weight, preferably at least 5% by weight, in the encapsulation 3. This reliably ensures that sufficient cavities 5 are formed in the encapsulation 3 due to shrinkage of the matrix material caused by aging.

[0063] The particles 4 are preferably present in the encapsulation in a proportion of at most 30% by weight, in particular at most 25% by weight, thereby ensuring that the encapsulation does not become too sticky during the production of the semiconductor component 1 .

[0064] In addition, the luminescent substance 35 can also be arranged in the encapsulation 3 , so that the semiconductor component 1 as a whole generates mixed radiation, for example mixed light that appears white to the human eye.

[0065] The described design of the package 3 is particularly suitable for optoelectronic semiconductor components 1 in which a high light output is required in continuous-wave operation, resulting in relatively high temperatures in the package 3. Consequently, such optoelectronic semiconductor components 1 present a higher risk of delamination effects due to aging-related shrinkage of the matrix material. With such optoelectronic semiconductor components 1, a high level of aging stability of the semiconductor component can be achieved, particularly with respect to the brightness and color coordinates of the emitted radiation, without having to reduce the power consumption of the optoelectronic semiconductor component.

[0066] In principle, however, the described package is suitable for all types of optoelectronic semiconductor components, in particular also for optoelectronic semiconductor chips 2 which are provided for receiving radiation.

[0067] This patent application claims the priority of German patent application 10 2019 134 904.4, the disclosure content of which is incorporated herein by reference.

[0068] The invention is not restricted by the description based on the exemplary embodiments. Instead, the invention comprises every novel feature and every combination of features, in particular every combination of features in the claims, even if this feature or this combination itself is not explicitly mentioned in the claims or exemplary embodiments.

[0069] Reference Signs List

[0070] 1 Optoelectronic semiconductor devices

[0071] 2 Semiconductor chips

[0072] 3 Packaging

[0073] 31 Matrix material

[0074] 35 Luminous substances

[0075] 39 Reference Package

[0076] 4 particles

[0077] 5 Cavity

[0078] 6 Housing

[0079] 61 lead frame

[0080] 7 Measurement curve

[0081] 8 Reference curves

[0082] 91 Arrow

[0083] 95 Arrow

Claims

1. An optoelectronic semiconductor component (1) comprising an optoelectronic semiconductor chip (2) and a package (3) comprising a matrix material (31), wherein the semiconductor chip is embedded in the package, wherein optically inert particles (4) are introduced into the matrix material of the package as crack nuclei, and wherein the package is designed such that during operation of the optoelectronic semiconductor component, cavities (5) are formed at least at some of the particles, which are arranged completely within the package and outside the particles.

2. The optoelectronic semiconductor device according to claim 1, wherein The encapsulation is designed such that aging-induced shrinkage of the matrix material leads to the formation of the cavity.

3. The optoelectronic semiconductor device according to claim 1 or 2, wherein: The particles are transmissive to the radiation to be generated or received by the optoelectronic semiconductor chip.

4. The optoelectronic semiconductor device according to claim 1 or 2, wherein: The particles consist of a material whose refractive index is adapted to the refractive index of the matrix material.

5. The optoelectronic semiconductor device according to claim 1 or 2, wherein: The refractive index of the material of the particles differs from the refractive index of the matrix material by at most 10%.

6. The optoelectronic semiconductor device according to claim 1 or 2, wherein: The refractive index of the material of the particles differs from the refractive index of the matrix material by at most 5%.

7. The optoelectronic semiconductor device according to claim 1 or 2, wherein: At least some of the particles have an angular basic shape.

8. The optoelectronic semiconductor device according to claim 1 or 2, characterized in that The particles have an average diameter between 5 μm and 30 μm, both inclusive.

9. The optoelectronic semiconductor device according to claim 1 or 2, wherein: The particles are present in the package in a proportion between 3% and 30% by weight, both inclusive.

10. The optoelectronic semiconductor device according to claim 1 or 2, characterized in that The particles are present in the package in a proportion between 5% and 25% by weight, both inclusive.

11. The optoelectronic semiconductor device according to claim 1 or 2, wherein: The matrix material is silicone.

12. The optoelectronic semiconductor device according to claim 1 or 2, characterized in that The matrix material has a refractive index between 1.4 and 1.6, inclusive.

13. A method for operating an optoelectronic semiconductor device, comprising the steps of: a) providing an optoelectronic semiconductor component (1) comprising an optoelectronic semiconductor chip (2) and a package (3) comprising a matrix material (31), wherein the semiconductor chip is embedded in the package, and wherein optically inert particles (4) are introduced as crack nuclei into the matrix material of the package; and b) operating the optoelectronic semiconductor component such that a cavity (5) is formed at least on some of the particles, the cavity being arranged completely within the encapsulation and outside the particles.

14. The method according to claim 13, wherein The optoelectronic semiconductor component is configured according to any one of claims 1 to 12 .

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