Optoelectronic semiconductor chip, method for manufacturing and application in an optoelectronic component

Abstract

Optoelectronic semiconductor chip (1) comprising: - an active layer (10) comprising a first and a second main surface (11, 12) of a semiconductor material which emits or receives radiation during operation of the semiconductor chip (1); - a structured layer (20) having three-dimensional structures for coupling out or coupling in radiation and arranged on the first main surface (11) in the beam path (40) of the active layer (10), wherein the structured layer (20) comprises an inorganic-organic hybrid material, wherein the inorganic-organic hybrid material - a hydrolytic condensate and - an organic prepolymer comprising, wherein the hydrolytic condensate contains organofunctional silanes with organic substituents that are at least partially crosslinked with the organic prepolymer.

Description

[0001] The invention relates to an optoelectronic semiconductor chip, a method for manufacturing the semiconductor chip, and an optoelectronic component comprising such a semiconductor chip.

[0002] The following publications describe an optoelectronic semiconductor chip: US 2005 / 0 141 240 A1 and WO 2007 / 031 929 A1.

[0003] Optoelectronic semiconductor chips often have roughened surfaces to improve the coupling or extraction of radiation. These roughened surfaces frequently contain structures created directly within the active layer of the semiconductor chip. Generally, it is desirable to couple radiation as completely as possible to increase the efficiency of the semiconductor chip. Furthermore, such a semiconductor chip should be durable and inexpensive to produce.

[0004] One problem to be solved according to at least one embodiment of the invention is to specify an optoelectronic semiconductor chip with improved properties.

[0005] Another task to be solved is to specify a method for manufacturing an optoelectronic semiconductor chip with improved properties and an optoelectronic component comprising such a semiconductor chip.

[0006] One aspect of the invention is an optoelectronic semiconductor chip comprising: - an active layer with a first and a second main surface, wherein the active layer comprises or consists of a semiconductor material and emits or receives radiation during operation of the semiconductor chip; - a structured layer that has three-dimensional structures for coupling out or coupling in radiation and is arranged on the first main surface in the beam path of the active layer, wherein the structured layer comprises or consists of an inorganic-organic hybrid material.

[0007] The optoelectronic semiconductor chip will also be referred to simply as the "semiconductor chip" in the following. In this context, "receiving radiation" means that the semiconductor chip can be used to detect radiation.

[0008] The three-dimensional structures particularly improve the coupling out or coupling in of radiation by reducing total reflections at the surface of the semiconductor chip.

[0009] The structured layer is at least partially located on the first primary surface of the active layer and can be located exclusively on the first primary surface. It can also completely cover the first primary surface of the active layer, although, for example, an area intended for electrical contacting of the semiconductor chip may be left uncovered. The structured layer can close or seal defects in the active layer, such as point defects, cracks, or microtubes. This can also apply to an area of ​​the first primary surface intended for electrical contacting. The active layer can therefore be protected from harmful influences, resulting in a longer lifetime for the semiconductor chip compared to conventional semiconductor chips where a surface of the active layer is roughened directly for the coupling of radiation.Defects extending through the entire active layer can also be closed or sealed by the structured layer, thereby reducing the risk of a short circuit during operation of the semiconductor chip.

[0010] The choice of semiconductor materials is not limited according to the invention. In particular, semiconductor materials that emit or receive radiation in the visible region of the spectrum (420 to 780 nm wavelength) are used. Furthermore, semiconductor materials that emit or receive radiation in the UV range (200 to 420 nm wavelength) or in the infrared range (≥ 780 nm wavelength) can be used. Such a semiconductor material can, for example, be based on nitride or phosphide compound semiconductors, or comprise or consist of GaAs or SiC. The semiconductor material can also, for example, be based on antimonide, arsenide, or II / VI compound semiconductors. Combinations of these semiconductor materials can also be used.

[0011] In this context, “based on nitride compound semiconductors” means that the active layer, or at least one layer thereof, is a nitride III / V compound semiconductor material, preferably Al n Ga m In 1-n-m N comprises, where 0 ≤ n ≤ 1, 0 ≤ m ≤ 1, and n + m ≤ 1. This material does not necessarily have to have a mathematically exact composition according to the formula above. Rather, it can contain one or more dopants as well as additional components that impart the characteristic physical properties of the aluminum. n Ga m In 1-n-m The N-materials do not change in essence. For the sake of simplicity, however, the formula above only includes the essential components of the crystal lattice (Al, Ga, In, N), even though these may be partially replaced by small amounts of other substances.

[0012] In this context, "based on phosphide compound semiconductors" means that the semiconductor body, especially the active layer, is preferably made of Al n Ga m In 1-n-m P comprises, where 0 ≤ n ≤ 1, 0 ≤ m ≤ 1, and n + m ≤ 1, preferably with n ≠ 0 and / or m ≠ 0. This material need not necessarily have a mathematically exact composition according to the formula above. Rather, it may contain one or more dopants as well as additional components that do not substantially alter the physical properties of the material. For the sake of simplicity, however, the formula above includes only the essential components of the crystal lattice (Al, Ga, In, P), even though these may be partially replaced by small amounts of other substances.

[0013] In this context, "based on antimonide compound semiconductors" means that the semiconductor body, especially the active region, is preferably made of Al n In m Ga1-n-m Sb comprises, where 0 ≤ n ≤ 1, 0 ≤ m ≤ 1, and n + m ≤ 1. This material does not necessarily have to have a mathematically exact composition according to the formula above. Rather, it may contain one or more dopants as well as additional components that do not substantially alter the physical properties of the material. For the sake of simplicity, however, the formula above only includes the essential components of the crystal lattice Al, In, Ga, Sb, even though these may be partially replaced by small amounts of other substances.

[0014] In this context, "based on arsenide compound semiconductors" means that the semiconductor body, especially the active region, is preferably made of Al n In m Ga 1-n-mAs comprises, where 0 ≤ n ≤ 1, 0 ≤ m ≤ 1, and n + m ≤ 1. This material does not necessarily have to have a mathematically exact composition according to the formula above. Rather, it may contain one or more dopants as well as additional components that do not substantially alter the physical properties of the material. For the sake of simplicity, however, the formula above only includes the essential components of the crystal lattice Al, In, Ga, As, even though these may be partially replaced by small amounts of other substances.

[0015] In this context, “based on II / VI compound semiconductors” means that the semiconductor body, in particular the active region, is preferably Zn n CD 1-n S m See 1-mThe formula includes the elements 0 ≤ n ≤ 1 and 0 ≤ m ≤ 1. This material does not necessarily have to have a mathematically exact composition according to the formula above. Rather, it can contain one or more dopants as well as additional components that do not substantially alter the physical properties of the material. For the sake of simplicity, however, the formula above only includes the essential components of the crystal lattice Zn, Cd, S, Se, even though these may be partially replaced by small amounts of other substances. The II-VI compound semiconductors include sulfides and selenides.

[0016] According to at least one further embodiment, the active layer is at least partially epitaxially grown. The active layer can also be entirely epitaxially grown. Epitaxially grown regions can be at least partially monocrystalline.

[0017] Such an epitaxial layer can be produced, for example, by metal-organic chemical vapor deposition (MOCVD). This process is generally very expensive and labor-intensive, as the organometallic materials used, such as Me3Ge or Me3Al, are typically expensive, sensitive to hydrolysis, and sometimes even pyrophoric. Furthermore, some chemicals, such as ammonia or hydrazine as a nitrogen source, are corrosive and / or toxic. The chemicals mentioned here as examples can be used to epitaxially produce InGaN. Suitable chemicals are also commercially available for other semiconductor materials.

[0018] In the semiconductor chip according to at least one embodiment of the invention, the active layer can have a smaller thickness than in conventional semiconductor chips, using the same materials and emitting or receiving the same amount of radiation. This reduces production costs compared to conventional semiconductor chips, as less material, particularly epitaxially grown material, is required for manufacturing. In conventional semiconductor chips, however, three-dimensional structures are created subtractively, for example, by etching into the active layer. This means that parts of the initially costly epitaxial material are removed. The areas where three-dimensional structures are created then usually contribute only marginally to the emission or reception of radiation.

[0019] According to a further embodiment, the active layer comprises several layers and can be arranged as a layer stack. At least one of the layers in the layer stack is epitaxially grown. Several or even all layers can be epitaxially grown, and the individual layers can comprise or consist of the same or different semiconductor materials.

[0020] The structured layer is transparent to the radiation emitted and received by the semiconductor chip. Transparent means that the structured layer has a transparency of ≥ 85%, and in particular ≥ 90%. The transparency can be ≥ 95%. Transparency is determined by transmission measurements. Fresnel losses, which occur at the entrance or exit of radiation (approximately 4% each), are not considered here.

[0021] Furthermore, the structured layer is particularly resistant to the radiation used. Therefore, the structured layer is not degraded by the radiation and / or there is little to no loss of transparency during operation. Over the average lifetime of the semiconductor chip, the structured layer retains at least 70%, and in particular at least 80%, of its original transparency. After the average lifetime of a semiconductor chip, it still retains approximately 70% of its initial brightness. Thus, the structured layer, which comprises or consists of an inorganic-organic hybrid material, differs fundamentally from a layer containing a photoresist and used, for example, as a mask in an etching process. Typically, in conventional semiconductor chips, such a photoresist-containing layer is removed after an etching process.

[0022] According to another embodiment, a reflective layer is arranged on the second main surface of the active layer. The reflective layer can also be arranged directly on the active layer. The reflective layer can be planar or structured. Radiation can be at least partially reflected by the reflective layer in such a way that it can then be coupled out of the semiconductor chip or detected in the active layer, thereby increasing the efficiency of the semiconductor chip.

[0023] According to a further embodiment, the reflective layer can comprise or consist of a metal. The metal can, for example, be selected from a group including silver, platinum, aluminum, and combinations or alloys of these metals. The alloys can also contain other metals in proportion. In particular, the reflective layer can comprise or consist of silver or silver alloys.

[0024] The fact that a first layer, a first area, or a first device is arranged or applied "on" a second layer, a second area, or a second device can mean that the first layer, the first area, or the first device is arranged or applied directly in direct mechanical and / or electrical contact with the second layer, the second area, or the second device, or with the two further layers, areas, or devices. It can also refer to indirect contact, in which further layers, areas, and / or devices are arranged between the first layer, the first area, or the first device and the second layer, the second area, or the second device, or with the two further layers, areas, or devices.

[0025] A barrier layer can be created on the second primary surface, or between the second primary surface and the reflective layer, to at least partially prevent the migration of metals, for example silver, from the reflective layer into the active layer. The barrier layer can be located directly on the second primary surface. Such a barrier layer can, for example, comprise or consist of TiWN.

[0026] According to another embodiment, the three-dimensional structures for coupling radiation out or in are present only in the structured layer. It follows that the active layer does not have such three-dimensional structures. The first principal surface on which the structured layer is arranged can therefore be flat or nearly flat. Nearly flat means that the first principal surface has a roughness with extrema of ≤ 50 nm and, in particular, ≤ 20 nm over a 5 µm x 5 µm area, or it can also be perfectly flat. This can be determined using an atomic force microscope (AFM).

[0027] According to another embodiment, the active layer has a thickness of ≤ 10 µm, and in particular ≤ 5 µm. The active layer can have a thickness of 0.4 to 2 µm, in particular 0.6 to 1.5 µm, and often 0.8 to 1.2 µm, for example 1 µm. The semiconductor chip can therefore be, for example, a thin-film LED chip.

[0028] According to another embodiment, the structured layer has a thickness of 0.5 to 3 µm, in particular 0.6 to 1.5 µm. The structured layer can, for example, have a thickness of 1.1 µm.

[0029] The three-dimensional structures can have a defined shape. According to the invention, the shape of the three-dimensional structures is not limited. They can be, for example, photonic crystal structures optimized by calculation or simulation and / or geometric shapes.

[0030] The shape of the three-dimensional structures can be chosen such that radiation striking the surface of the structured layer is either directly coupled out, or that totally reflected radiation, after a second reflection at the opposite side of the semiconductor chip (e.g., at a reflective layer), strikes the surface of the structured layer at such an angle that total internal reflection does not occur. This increases the radiation extraction from the semiconductor chip, or the efficiency of a radiation-emitting semiconductor chip. In a radiation-receiving semiconductor chip, such three-dimensional structures improve the coupling of radiation.

[0031] According to a further embodiment, the three-dimensional structures in the structured layer are selected from a group comprising pyramidal, prismatic, cuboid, truncated pyramidal, conical, and truncated conical structures, and combinations thereof. The three-dimensional structures are, in particular, arranged close together.

[0032] According to another embodiment, the three-dimensional structures are formed with a resolution of ≤ 3 µm, and in particular 0.08 to 2 µm. These three-dimensional structures often have a resolution of 0.5 to 2 µm. Three-dimensional structures, for example formed as photonic crystals, can also have a resolution of ≤ 0.5 µm, for example 0.1 to 0.3 µm, so that the resolution is in the range of a quarter to half a wavelength of visible radiation.

[0033] The structured layer can have recesses between the three-dimensional structures. The shape of these recesses can be arbitrary and depends primarily on the three-dimensional structures. Such a recess may, but does not necessarily have to, be bounded on all lateral sides by the structured layer.

[0034] According to a further embodiment, the recesses in the structured layer have a depth of at least 0.5 to 2.8 µm, in particular 0.6 to 1.4 µm, for example 1 µm. In the area of ​​such a recess, the thickness of the structured layer can be at least 5 nm, in particular at least 20 nm, with the layer thickness generally being ≤ 50 nm. Thus, the structured layer can also be free of perforations in the area of ​​the recesses (between the structures), so that the active layer is protected or defects in the active layer are at least partially closed or sealed. The active layer can also be at least partially uncovered by the structured layer, for example, in an area where the semiconductor chip is to be electrically contacted.

[0035] The inorganic-organic hybrid material comprises - an organic prepolymer and - a hydrolytic condensate, wherein the hydrolytic condensate contains organofunctional silanes with organic substituents that are at least partially crosslinked with the organic prepolymer. The inorganic-organic hybrid material, occasionally also referred to as an inorganic-organic hybrid polymer, can consist largely (corresponding to a content of at least 90 wt%) or entirely of an organic prepolymer and a hydrolytic condensate.

[0036] The production of such an inorganic-organic hybrid material is described, for example, in DE 43 03 570 C2 and the references cited therein, the content of which is hereby incorporated by reference. According to a further embodiment, the hydrolytic condensate can be produced from condensable compounds that are at least partially hydrolyzed and then condensed to form the hydrolytic condensate. The condensable compounds are at least partially composed of organofunctional silanes of the formula R''' m SiX 4-m selected. An organofunctional silane or a combination of different organofunctional silanes of this formula can be used. The following correspond to: R''' = crosslinkable organic substituent, X = hydrolyzable and condensable group, m = 1, 2 or 3, in particular 1.

[0037] Organofunctional silanes of formula R''' m SiX 4-mand the meanings of R''' and X are described in detail in DE 43 03 570 C2, the content of which is hereby incorporated by reference. From organofunctional silanes of the formula R''' m SiX 4-m Organofunctional silanes with crosslinkable organic substituents are formed in the hydrolytic condensate. In the inorganic-organic hybrid material, these organic substituents are at least partially crosslinked with the organic prepolymer.

[0038] According to a further embodiment, the hydrolytic condensate can be produced using additional condensable compounds selected from condensable compounds of formula MY4 of titanium and / or zirconium and combinations of these compounds. Here, M represents the metal titanium (Ti) or zirconium (Zr). Y represents a hydrolyzable and condensable group, whereby several Ys can also correspond to a chelating ligand. Chelating ligands such as β-diketones can increase the stability of these compounds. Y can be individually selected in each compound; thus, a compound of formula MY4 can have up to four different Ys. Suitable titanium and / or zirconium compounds of formula MY4 for the inorganic-organic hybrid material are described in DE 34 07 087 A1, the contents of which are hereby incorporated by reference.

[0039] According to another embodiment, the hydrolytic condensate can be produced using further condensable compounds consisting of organofunctional silanes of formula R' m SiX 4-m are selected, where R' = non-crosslinkable organic residue. Furthermore, the hydrolytic condensate can be prepared using other condensable compounds chosen from low-volatility oxides, for example B₂O₃, P₂O₃, and SnO₂. Organofunctional silanes of the formula R' m SiX 4-m and semi-volatile oxides are described in DE 43 03 570 C2 and the references mentioned therein, the content of which is hereby incorporated by reference.

[0040] A hydrolytic condensate can be produced from the condensable compounds, which can also be combinations of different condensable compounds, using a sol-gel process. The hydrolytic condensate can be produced entirely by condensing the condensable compounds described above.

[0041] Suitable crosslinkable organic prepolymers are described, for example, in DE 43 03 570 C2, the contents of which are hereby incorporated by reference.

[0042] According to an alternative embodiment, the inorganic-organic hybrid material comprises a second hydrolytic condensate, which can be prepared from condensable compounds that are optionally at least partially hydrolyzed and then condensed. The inorganic-organic hybrid material can consist entirely of the second hydrolytic condensate. The condensable compounds comprise organofunctional silanes of formula R' m SiX 4-m with 1 ≤ m ≤ 3 and in particular m = 1.

[0043] Here, R' is a non-crosslinkable organic residue that remains in the inorganic-organic hybrid material. Furthermore, X is a hydrolyzable and / or condensable group that does not (completely) remain in the inorganic-organic hybrid material. Suitable organofunctional silanes of the formula R' m SiX 4-mare described, for example, in DE 43 03 570 C2 and the references cited therein, the content of which is hereby incorporated by reference. X can be selected from a group comprising alkoxy, hydroxy, chloride, and combinations thereof. R' can, in particular, be selected from a group comprising alkyl substituents with up to 8 carbon atoms, aryl substituents, and combinations thereof. For example, R' can be selected from a group comprising methyl, ethyl, propyl, isopropyl, cyclohexyl, phenyl, and combinations thereof. Combinations of different organofunctional silanes of the formula R' are also possible. m SiX 4-m be used.

[0044] According to a further development of this embodiment, the condensable compounds for the preparation of the second hydrolytic condensate comprise titanium and / or zirconium compounds of formula MY4, as already described above. Oxides and hydroxides of titanium and / or zirconium can also be used.

[0045] According to a further development of this embodiment, the condensable compounds for the preparation of the second hydrolytic condensate comprise silicon compounds of the formula SiX4. Here, X has the same meaning as previously explained.

[0046] From the organofunctional silanes of formula R' m SiX 4-mA second hydrolytic condensate can be produced using a sol-gel process with the titanium and / or zirconium compounds of formula MY4 and, optionally, silicon compounds of formula SiX4. This second hydrolytic condensate can be stored for at least several months without loss of quality. It is not yet fully condensed and therefore still contains Si-OH groups and, optionally, Ti-OH and / or Zr-OH groups. The actual inorganic-organic hybrid material can be obtained by hardening this second hydrolytic condensate.

[0047] According to another embodiment, the inorganic-organic hybrid material is a so-called spin-on glass.

[0048] According to another embodiment, the inorganic-organic hybrid material comprises nanoparticles containing or consisting of TiO2 and / or ZrO2.

[0049] According to another embodiment, the structured layer has a refractive index of ≥ 1.6. A high refractive index enables good radiation extraction, as few total internal reflections occur at the first principal surface.

[0050] In a further development of this embodiment, the structured layer has a refractive index of ≥ 1.8 and, in particular, ≥ 1.9. The refractive index can be ≥ 2.0, for example, 2.2. The refractive index can be chosen to be as high as possible in order to increase the coupling of light from the semiconductor chip. A high refractive index is also advantageous for radiation-detecting semiconductor chips.

[0051] Refractive indices are determined using a refractometer, where the temperature can be read and adjusted. The refractive indices are determined at the wavelength of the sodium D-line (approximately 589 nm) and at a temperature of 20°C. This is known as the nc. D20 specified.

[0052] According to a further embodiment, the inorganic-organic hybrid material contains at least 20 wt%, in particular at least 30 wt%, of titanium and / or zirconium (wt% = weight percent). The inorganic-organic hybrid material can contain ≥ 40 wt% and in particular ≥ 50 wt% of titanium and / or zirconium, with titanium being used in particular.

[0053] The stated titanium and / or zirconium content refers to the weight fraction of titanium and / or zirconium atoms (usually present as Ti(IV) or Zr(IV)) in the inorganic-organic hybrid material. Oxygen atoms or other ligands are not included. A high titanium and / or zirconium content results in a high refractive index for the structured layer.

[0054] According to another embodiment, the structured layer is arranged directly on the first main surface of the active layer. In particular, the structured layer can adhere well to the active layer or to the semiconductor materials within the active layer without the need for adhesives or a separate adhesive layer. This eliminates the need for adhesives and the step of applying adhesives between the active and structured layers during the manufacturing of the semiconductor chip. This reduces the production costs for such a semiconductor chip.

[0055] The strong adhesion of the structured layer (directly) to the active layer can be attributed in particular to the inorganic components in the inorganic-organic hybrid material. Due to this strong adhesion, the structured layer is insensitive to mechanical stress, allowing even delicate three-dimensional structures to exhibit good stability. Since the material used for radiation extraction and / or coupling is at least partially an inorganic-organic hybrid material, the structured layer is not brittle despite its durability and hardness. This property can be attributed primarily to the organic components. Consequently, the three-dimensional structures can exhibit higher fracture toughness than conventional devices where structures are made of a (brittle) semiconductor material.The high mechanical resistance of the structured layer also protects the underlying active layer of the semiconductor chip, thus giving the semiconductor chip a longer lifespan.

[0056] As a further aspect of the invention, a method for producing a semiconductor chip according to at least one embodiment of the invention is specified, wherein the method comprises the following process steps: (a) Providing a body comprising the active layer with a first and a second principal surface; (b) Applying a coating material to the first main surface; (c) Structuring the coating material; and (d) Hardening of the coating material to form the inorganic-organic hybrid material, whereby the structured layer is formed.

[0057] The body can be the size of a chip, allowing a single semiconductor chip to be manufactured using this process. Alternatively, the body can be larger, enabling the parallel production of multiple semiconductor chips. Such a body can feature mesa etchings, which facilitate easy separation (separation). The body can also be a wafer.

[0058] The process does not use an etching process, and in particular, no etching into the active layer, to create the three-dimensional structures on the surface of the semiconductor chip. As previously explained, therefore, fewer or no crystal defects in the active layer are revealed or even exacerbated compared to a conventional process involving etching. This significantly improves the quality of the active layer and minimizes rejects during semiconductor chip manufacturing.

[0059] The process according to the invention is particularly easy to carry out and cost-effective, as it requires fewer work steps and fewer materials or chemicals than a conventional process. In a conventional process based on photolithography with an etching step, a photoresist is first applied and then structured. Using the structures in the photoresist as a mask, an etching process is then carried out into an active layer, and the excess photoresist is subsequently removed. In this process, the active layer must have a high thickness to prevent punctures during etching. In contrast, the process according to the invention only requires the application, structuring, and curing of a coating material. The active layer, which is complex and expensive to produce, therefore remains completely within the semiconductor chip.

[0060] In the process according to the invention, three-dimensional structures are formed in process step (d) which can exhibit the properties already described. For example, the structures can be formed with high resolution. In contrast to a conventional process with an etching step, rounding effects that can interfere with the coupling out or coupling of light are avoided in this process. This improves the coupling out or coupling of radiation.

[0061] The body provided in process step (a) can be obtained, for example, by epitaxially creating an active layer on a monocrystalline substrate. A barrier layer and a reflective layer can then be created on the second main surface. The substrate can then be removed, exposing the first main surface.

[0062] According to a further embodiment, the coating material is at an elevated temperature during the structuring process step (c). This elevated temperature can range from room temperature (25°C) to 100°C, and particularly from 40°C to 80°C. Heating can be performed before or during process step (c). This allows the coating material to effectively fill the spaces within the die, enabling the formation of high-resolution three-dimensional structures.

[0063] The materials or manufacturing process for the stamp used are not limited according to the application. For example, a silicon stamp with a structured layer of gallium nitride on its surface can be used. Such a stamp is easy and inexpensive to manufacture. The stamp can, for example, be mounted on a piston or a roller. The stamp can also be part of a flexible foil or film, as is the case, for example, in the IPS. ® -Procedure of Obducat or in the SCIL ® This is the case with the Philips process. Multiple stamps can also be used in parallel.

[0064] According to another embodiment, process steps (c) and (d) are carried out together. This can simplify the process, as the stamp can be removed more easily after the coating material has hardened.

[0065] Process steps (c) and (d) can therefore be carried out analogously to nanoimprint lithography (NIL). In contrast to conventional NIL, however, the generated structures are not used as a mask for an etching process, but remain as a structured layer in the semiconductor chip.

[0066] According to another embodiment, in process step (d) for hardening, the material is irradiated and / or heated.

[0067] According to a further development of this embodiment, in process step (d) the coating material is irradiated with UV radiation to harden it. Alternatively, infrared radiation, beta radiation, or gamma radiation can be used. It can be applied with a radiation energy of 0.5 to 12 J / cm². 2are irradiated. The radiation energy used can depend on the thickness of the coating material. For example, with a layer thickness of 0.8 µm, 8 J / cm² can be used. 2 be irradiated.

[0068] According to a further embodiment, in process step (d) for hardening, the material is heated to 80 to 400°C, in particular to 150 to 350°C. This heating can be carried out in a single stage or in multiple stages. For example, the hardening can be carried out in two stages, with the material first being heated to 80 to 150°C, for example for 2 minutes, and then heated to 150°C to 350°C in a second stage.

[0069] According to a further embodiment, the punch used in process steps (c) and (d) is transparent to the radiation used for hardening. Advantageously, the radiation source for the hardening radiation can therefore be arranged behind the punch. This allows for uniform hardening of the coating material to form the inorganic-organic hybrid material. A heating device can also be arranged in or behind the punch.

[0070] According to another embodiment, the coating material is applied in process step (b) by centrifugal coating, spraying, or spin coating. The coating material can also be applied using another, analogous method. The coating material can be applied directly to the active layer.

[0071] According to a further embodiment, in process step (b) the coating material is applied as a layer with a thickness of 0.2 to 1.5 µm, in particular 0.3 to 1 µm, for example 0.8 µm. The coating material therefore has a smaller thickness than the structured layer. In process step (c), the coating material is structured by deforming it, thereby increasing the layer thickness in the area of ​​the structures.

[0072] In the process according to the invention, either a first or a second coating material can be applied as the coating material in process step (b). In this application, the term "coating material" refers to both the first and the second coating material.

[0073] According to another embodiment, the first coating material - a hydrolytic condensate comprising organofunctional silanes with crosslinkable organic substituents, - a crosslinkable organic prepolymer, and - an organic solvent include or consist of.

[0074] The hydrolytic condensate and crosslinkable organic prepolymers have already been described above. The consistency of the first coating material can be adjusted as desired using the solvent, ensuring easy processing. Such a first coating material can be used to form a structured layer comprising or consisting of an inorganic-organic hybrid material.

[0075] According to a further embodiment, the organic solvent in the first coating material is selected from the group comprising an alcohol, an ether, a monoether of a diol or triol, an ester, a carboxylic acid, and combinations of these solvents. For example, the organic solvent may be selected from the group comprising methanol, ethanol, 1-propanol, 2-propanol, 1,2-propanediol, 1-butanol, 2-butanol, 1,2-butanediol, propylene glycol monoethyl ether, 1-methoxy-2-propanol, acetic acid, and a combination of these solvents. Typically, dried solvents containing little or no water are used.

[0076] According to a further embodiment, the first coating material consists largely or entirely of the hydrolytic condensate, at least one organic prepolymer, and at least one organic solvent. "Largely" here means at least 95% by weight of the total first coating material.

[0077] According to a further embodiment, in a further process step the first coating material is provided by first producing a hydrolytic condensate from the condensable compounds described above using a sol-gel process. In a second step, the hydrolytic condensate is then mixed with at least one crosslinkable organic prepolymer and at least one organic solvent. Such a first coating material can be stored for at least several months without loss of quality. Commercial coating materials such as Amonil can also be used. ®used by Amo GmbH.

[0078] According to an alternative embodiment, a second coating material can comprise a second hydrolytic condensate. The second hydrolytic condensate can be produced via a sol-gel process, as described above. The second coating material can comprise an organic solvent, as previously described for the first coating material. The solvent can be used to adjust the consistency of the second coating material as desired, ensuring good processability. The second coating material can consist entirely of the second hydrolytic condensate and an organic solvent. For example, a commercially available mixture for producing so-called spin-on glass can be used as the second coating material.

[0079] According to a further embodiment, the coating material in process step (b) has a viscosity of ≤ 5 Pa*s, in particular ≤ 2 Pa*s, when applied. The coating material can have a viscosity of ≤ 0.2 Pa*s, for example 0.05 Pa*s. Since the coating material has a low viscosity, application is facilitated and the active layer is well wetted by the coating material. This allows a uniform, thin layer to be obtained. The desired viscosity can be adjusted via the solvent. The coating material can contain up to 60 wt%, in particular up to 50 wt%, of solvent.

[0080] According to a further embodiment, the coating material used in process step (b) contains nanoparticles that contain or consist of TiO2 and / or ZrO2. These nanoparticles can be at least partially bonded to the inorganic-organic hybrid material during hardening in process step (d).

[0081] According to a further embodiment, the coating material is tempered in a further process step before structuring in process step (c). This removes at least some of the solvent and increases the viscosity of the coating material. Partial crosslinking can already occur at this stage. After tempering, the coating material can have a plastic, viscous consistency. Tempering can be carried out in a single stage or in multiple stages. For example, it can first be heated to 110°C for 2 minutes to remove solvents. Subsequently, it can be exposed to UV radiation and simultaneously structured with a stamp.

[0082] The body used in the process can be divided in a further process step after process step (b) and before process step (c). This can be done, for example, due to previously created or already present mesa etchings in the body. For example, the body can be divided to the size of a semiconductor chip, so that process steps (c) and (d) are carried out separately for each semiconductor chip. It is also possible to separate the body after process step (d).

[0083] According to a further embodiment, photolithography is performed in a further process step (e) following process step (c). This allows for the creation of a further roughening, for example, locally limited. For instance, as described above, a coating material can be structured on a body, such as a wafer, and subsequently roughened further by photolithography. This can be done after alignment or adjustment to structures on the body, which are intended, for example, for electrical contact.

[0084] According to a further embodiment, the structuring in process step (c) is carried out by aligning or adjusting a stamp to structures on the body as described above. A transparent stamp can be used for this purpose.

[0085] According to a further embodiment, a passivation layer is applied, at least partially, to the body or the semiconductor chip in a further process step. This protects the semiconductor chip from harmful environmental influences, such as diffusing moisture or oxygen, thereby increasing its lifespan and durability. Such a passivation layer can be produced, for example, by plasma-enhanced electronic vapor deposition (PECVD).

[0086] As a further aspect of the invention, an optoelectronic component is specified, comprising a semiconductor chip according to at least one embodiment of the invention. The optoelectronic component will hereinafter also be referred to simply as the "component".

[0087] The advantages previously described for the semiconductor chip according to at least one embodiment of the invention can also be obtained for the optoelectronic component.

[0088] The component can be configured as either a radiation-emitting or a radiation-detecting component. It can also include other components commonly found in optoelectronic devices. Examples of radiation-detecting components include sensors or photovoltaic elements such as solar cells. The following section describes a radiation-emitting component as an example.

[0089] The component can have a housing with a recess in which the semiconductor chip can be arranged. The recess can be partially or completely filled with a potting compound made of a polymer material such as silicone and / or an epoxy resin. Furthermore, the component can have converter materials in the beam path of the active layer that convert at least part of the radiation emitted by the semiconductor chip into further radiation with a different, longer wavelength. The component can emit radiation with any color appearance, in particular with a white color appearance.

[0090] The component can, for example, include a plate-shaped conversion element comprising converter materials and located near or on the semiconductor chip (so-called chip-level conversion). Alternatively, particles containing or consisting of the converter material can be distributed throughout the encapsulating compound. A conversion element can also be located at a distance, for example, > 750 µm, from the semiconductor chip (so-called remote phosphor conversion). The emitted radiation can also be coupled into a light guide and then emitted after possible conversion.

[0091] In this component, the semiconductor chip can be contacted, for example, via a bond wire in conjunction with a bond pad on the top surface. A reflective layer on the underside of the semiconductor chip can serve for electrical contact. Furthermore, the component can have electrically conductive leads that extend from the package and serve for electrical contact with the semiconductor chip.

[0092] The invention is explained in more detail below with reference to exemplary embodiments and drawings. In each figure, the same reference numerals denote the same elements. However, no scale references are shown; rather, individual elements may be enlarged and / or depicted schematically for better understanding.

[0093] They show Fig. 1 an optoelectronic semiconductor chip according to at least one embodiment of the invention, and Fig. 2 an optoelectronic component according to at least one embodiment of the invention.

[0094] In Fig. Figure 1 shows an optoelectronic semiconductor chip 1 comprising an active layer 10. The active layer 10 has a first main area 11 and a second main area 12 and comprises an electroluminescent semiconductor material, for example, InGaN. The active layer 10 can also be configured as a stack of layers. The active layer 10 is partially or completely epitaxially grown. The active layer 10 has a thickness of 0.4 to 2 µm, in particular 0.6 to 1.5 µm, such as 1 µm. The semiconductor chip 1 can, for example, be a thin-film LED chip.

[0095] In this embodiment, a structured layer 20 is arranged directly on the planar first main surface 11. Thus, no three-dimensional structures are created in the active layer 10. The structured layer 20 has a thickness of 0.6 to 1.5 µm, for example 1.1 µm, with the layer thickness being at least 5 nm and, in particular, at least 20 nm in the regions between the three-dimensional structures. Any defects in the active layer 10 are at least partially closed or sealed by the structured layer 20. The structured layer 20 consists of an inorganic-organic hybrid material and comprises ≥ 40 wt%, in particular ≥ 50 wt%, titanium (present as Ti(IV)). The refractive index of the structured layer 20 is ≥ 2.0, for example 2.2.This allows the radiation to pass through the layer boundary between active layer 10 and structured layer 20 with few total reflections and then be coupled out.

[0096] The structured layer 20 has three-dimensional structures formed with a resolution of 0.08 to 2.0 µm, and in particular 0.5 to 2.0 µm, and advantageously without rounding effects. The following are representative of possible three-dimensional figures in the Fig. 1. Cuboid structures 21, pyramidal structures 22, and prismatic structures 23 are shown. As explained above, the shapes of the three-dimensional structures are not limited to these. In particular, triangular pyramids 22 can enable effective coupling out (or coupling in) of radiation. Hexagonal pyramids (not shown) are also of interest due to their optimal surface area. A region can be recessed in the structured layer in which the active layer can be electrically contacted (not shown).

[0097] On the second main surface 12, a barrier layer 31 and a reflective layer 30, comprising silver, are produced. The barrier layer 31 serves to prevent silver migration and may comprise TiWN. The reflective layer 30 and / or the barrier layer 31 may be structured (not shown).

[0098] In the Fig. Figure 1 shows a beam 40a, which is directly coupled out, and a beam 40b, which is coupled out after reflection at the reflecting layer 30, representing a radiation-emitting semiconductor chip 1.

[0099] The semiconductor chip 1 shown is, as described above, particularly easy to manufacture, inexpensive and with little waste, and has a high durability or lifespan.

[0100] In Fig.Figure 2 shows an optoelectronic component 100 comprising a semiconductor chip 1 according to at least one embodiment of the invention. The component 100 has a housing 50 with a recess 55 in which the semiconductor chip 1 is arranged. The component 100 contains a converter material 65, which here is arranged in the form of a plate in the beam path 40 on the semiconductor chip 1. The recess 55 can be filled with a silicone potting compound 60. The semiconductor chip 1 is connected at its upper surface to a bond pad 72 via a bond wire 71. Electrically conductive leads 70a, 70b can extend from the housing 50 and serve for electrical contacting the semiconductor chip 1. In operation, the component 100 can emit radiation with any desired color appearance, in particular white.

[0101] As described above, the component 100 can also be implemented without converter material 65 or have a differently arranged converter material 65.

Claims

[1] Optoelectronic semiconductor chip (1) comprising: - an active layer (10) comprising a first and a second main surface (11, 12) of a semiconductor material which emits or receives radiation during operation of the semiconductor chip (1); - a structured layer (20) having three-dimensional structures for coupling out or coupling in radiation and arranged on the first main surface (11) in the beam path (40) of the active layer (10), wherein the structured layer (20) comprises an inorganic-organic hybrid material, wherein the inorganic-organic hybrid material - a hydrolytic condensate and - an organic prepolymer comprising, wherein the hydrolytic condensate contains organofunctional silanes with organic substituents that are at least partially crosslinked with the organic prepolymer. [2] Optoelectronic semiconductor chip (1) according to the preceding claim, wherein a reflective layer (30) is arranged on the second main surface (12) of the active layer (10). [3] Optoelectronic semiconductor chip (1) according to one of the preceding claims, wherein the three-dimensional structures for coupling out or coupling in radiation are only present in the structured layer (20). [4] Optoelectronic semiconductor chip (1) according to one of the preceding claims, wherein the active layer (10) has a layer thickness of 0.4 to 2 µm. [5] Optoelectronic semiconductor chip (1) according to one of the preceding claims, wherein the structured layer (20) has a layer thickness of 0.5 to 3 µm. [6] Optoelectronic semiconductor chip (1) according to one of the preceding claims, wherein the three-dimensional structures are formed with a resolution of ≤ 3 µm. [7] Optoelectronic semiconductor chip (1) according to any of the preceding claims, wherein the inorganic-organic hybrid material contains at least 20 wt% titanium and / or zirconium. [8] Optoelectronic semiconductor chip (1) according to the preceding claim, wherein titanium and / or zirconium is chemically bonded to the inorganic-organic hybrid material. [9] Optoelectronic semiconductor chip (1) according to one of the preceding claims, wherein the structured layer (20) has a refractive index of ≥ 1.

6. [10] Optoelectronic semiconductor chip (1) according to one of the preceding claims, wherein the structured layer (20) is arranged directly on the active layer (10). [11] Method for producing the optoelectronic semiconductor chip (1) according to any one of claims 1 to 10 comprising the method steps: (a) Providing a body comprising the active layer (10) with a first and second principal surface (11, 12); (b) Applying a coating material to the first main surface (11); (c) Structuring the coating material; and (d) Hardening of the coating material to form the inorganic-organic hybrid material, wherein the structured layer (20) is formed, wherein the inorganic-organic hybrid material - a hydrolytic condensate and - an organic prepolymer comprising, wherein the hydrolytic condensate contains organofunctional silanes with organic substituents that are at least partially crosslinked with the organic prepolymer. [12] Method according to claim 11, wherein a stamp is used in process step (c) to structure the coating material. [13] Method according to any one of claims 11 to 12, wherein the method steps (c) and (d) are carried out together. [14] Method according to any one of claims 11 to 13, wherein the coating material is applied as a layer with a layer thickness of 0.2 to 1.5 µm in process step (b). [15] Optoelectronic component (100) comprising an optoelectronic semiconductor chip (1) according to any one of claims 1 to 10.

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