Optoelectronic component and method for producing an optoelectronic component

Abstract

In at least one embodiment, the optoelectronic component (1) comprises at least one optoelectronic semiconductor chip (2), at least one optical element (3) and an intermediate layer (4) between the at least one optoelectronic semiconductor chip (2) and the at least one optical element (3). The at least one optoelectronic semiconductor chip (2) is designed to emit radiation in a first wavelength range. The at least one optical element (3) is formed with a material that is transparent to radiation in a second wavelength range (6). The intermediate layer (4) comprises a material that is transparent to radiation from the first wavelength range and absorbent to radiation from the second wavelength range (6). The first wavelength range comprises other wavelengths than the second wavelength range (6).

Description

[0001] Description

[0002] OPTOELECTRONIC COMPONENT AND METHOD FOR PRODUCING AN OPTOELECTRONIC COMPONENT

[0003] An optoelectronic component is specified. Furthermore, a method for producing an optoelectronic component is specified.

[0004] One of the problems to be solved is to provide an optoelectronic component characterized by high light extraction and long lifetime. Another problem to be solved is to provide a method for producing such a component.

[0005] These objects are achieved by a subject matter having the features of independent patent claim 1 or by a method having the features of independent patent claim 10. Advantageous embodiments and further developments are the subject matter of the respective dependent patent claims.

[0006] According to at least one embodiment of the optoelectronic component, it comprises at least one optoelectronic semiconductor chip which is configured to emit radiation in a first wavelength range.

[0007] The at least one optoelectronic semiconductor chip comprises, for example, a semiconductor layer sequence with an active zone. The active zone serves to generate or absorb electromagnetic radiation. The active zone is, for example, provided with a II IV

[0008] Compound semiconductor material formed.

[0009] In principle, it is possible for electromagnetic radiation in the blue, green, or red spectral range, or in the UV range, or in the IR range, to be generated in the active zone during intended operation. Preferably, radiation in the UV range is generated during intended operation of the active zone, particularly in the so-called UVC range of the electromagnetic spectrum. In particular, the radiation generated in the active zone during operation is radiation in the first wavelength range.

[0010] The at least one optoelectronic semiconductor chip further comprises, for example, a chip substrate. The semiconductor layer sequence is arranged on a main side of the chip substrate. The chip substrate is, for example, a growth substrate of the semiconductor layer sequence. The chip substrate preferably comprises sapphire or is formed therefrom. The at least one optoelectronic semiconductor chip is preferably a volume emitter, in particular a sapphire chip.

[0011] On a side of the semiconductor layer sequence facing away from the chip substrate, contact points for contacting and powering the semiconductor layer sequence are arranged. The optoelectronic semiconductor chip is preferably a flip chip.

[0012] Preferably, the optoelectronic semiconductor chip is a light-emitting diode, or LED for short. Alternatively, the optoelectronic semiconductor chip can be a laser diode, such as a card emitter or a surface-emitting semiconductor laser diode, also known as a VCSEL for short.

[0013] According to at least one embodiment, the optoelectronic component comprises at least one optical element. The at least one optical element is designed, for example, to shape the beam of radiation from the first wavelength range. The at least one optical element is, for example, a lens, a prism or a metalens structure. During intended operation, radiation emitted by the at least one semiconductor chip can be directed by the optical element, for example in a main emission direction. The main emission direction is preferably perpendicular to a main extension direction of the semiconductor layer sequence or the active zone and is a direction in which the radiation from the first wavelength range, which is emitted by the optoelectronic component during operation, has its intensity maximum.

[0014] According to at least one embodiment, the optoelectronic component comprises an intermediate layer which is arranged between the at least one optoelectronic semiconductor chip and the at least one optical element. The intermediate layer serves, for example, as an adhesion promoter in order to secure the at least one optical element to the at least one semiconductor chip. The intermediate layer is preferably in direct contact with the at least one semiconductor chip and in direct contact with the at least one optical element. The intermediate layer has, for example, a thickness of 1 pm up to and including 5 pm. Roughness of a surface of the at least one optoelectronic semiconductor chip and / or of the at least one optical element on which the intermediate layer is arranged can advantageously be compensated for by means of the intermediate layer.

[0015] For example, the intermediate layer is arranged on a main emission surface of the at least one optoelectronic semiconductor chip. During intended operation, a large part, for example at least 50% or at least 75%, of the radiation generated in the active zone is emitted via the main emission surface. If the at least one optoelectronic semiconductor chip is, for example, a sapphire chip, the main emission surface is in particular a surface of the chip substrate which lies opposite the semiconductor layer sequence. If, on the other hand, the optoelectronic semiconductor chip is, for example, a laser diode, the main emission surface is preferably a facet of the laser diode.

[0016] According to at least one embodiment of the optoelectronic component, the at least one optical element is formed with a material that is transparent to radiation from a second wavelength range. For example, the material of the optical element comprises glass. Alternatively or additionally, it is possible for the optical element to be formed with sapphire and / or quartz. If here and below a material or an element is referred to as "transparent" to a specific radiation, then it has, in particular, a transmittance of at least 80% or at least 90% or at least 95% with respect to this radiation. According to at least one embodiment of the optoelectronic component, the intermediate layer comprises a material that is transparent to radiation from the first wavelength range and absorbent to radiation from the second wavelength range.If a material or an element is described here and below as "absorbing" for a particular radiation, it has in particular a reflectance of at least 80% or at least 90% or at least 95% with respect to this radiation.

[0017] The intermediate layer comprises, for example, a glass. The intermediate layer is, for example, adapted such that it has a high transmission at a wavelength of 275 nm and is absorbent at a shorter wavelength. The material of the intermediate layer is, in particular, adapted such that it is insensitive to radiation from the first wavelength range. This means that the intermediate layer is not decomposed or damaged by radiation in the first wavelength range. If, for example, the semiconductor chip is a sapphire chip which emits radiation in the UVC range during operation, i.e. the first wavelength range is the UVC range, the intermediate layer is preferably UV-stable.

[0018] In particular, the intermediate layer is free of organic material. Preferably, the intermediate layer consists completely of inorganic materials. The material of the intermediate layer is adapted, for example, such that the intermediate layer can be heated by radiation from the second wavelength range. According to at least one embodiment of the optoelectronic component, the first wavelength range has different wavelengths than the second wavelength range. For example, the first wavelength range and second wavelength range are each contiguous ranges that do not overlap. This means, in particular, that every wavelength that is in the first wavelength range is not contained in the second wavelength range and vice versa.

[0019] In at least one embodiment, the optoelectronic component has at least one optoelectronic semiconductor chip, at least one optical element, and an intermediate layer between the at least one optoelectronic semiconductor chip and the at least one optical element. The at least one optoelectronic semiconductor chip is configured to emit radiation in a first wavelength range. The at least one optical element is formed with a material that is transmissive to radiation in a second wavelength range. The intermediate layer comprises a material that is transmissive to radiation from the first wavelength range and absorbent to radiation from the second wavelength range. The first wavelength range comprises a different wavelength than the second wavelength range.

[0020] The present optoelectronic component is based on the following technical considerations. Currently, for components that comprise a semiconductor chip, in particular a semiconductor chip that emits in the UVC range, and a lens, a fluoropolymer lens is usually applied directly to the semiconductor chip by means of potting or modeling. In this case, it is difficult to select process conditions such that neither the semiconductor chip nor other materials are damaged, while still ensuring sufficient component stability. The main problems here are delamination and reduced material service life. One of the reasons for this is the high temperatures during curing of the fluoropolymer lens, which can also damage the semiconductor chip.

[0021] Alternative concepts implement glass lenses, which are applied to an optical carrier and, for example, fixed relative to the semiconductor chip. However, this results in a material transition from the semiconductor chip material to air, followed by a material transition from air to glass and another material transition from glass to air, which is detrimental to light extraction in the direction of emission. Due to the resulting total internal reflection, not only efficiency losses but also the lens effect are counteracted.

[0022] Another option is to apply a glass lens using a process known as fusion bonding. However, this places very high demands on the roughness and cleanliness of the surfaces of the semiconductor chip and the glass lens. Typically, a roughness of Ra of less than 1 nm is required, where Ra denotes the average roughness. This can only be achieved using a special manufacturing process. For these processes, for example, an artificial wafer must be created for the glass lens and the semiconductor chip, with the lenses being embedded in a matrix material in order to then achieve the required surface quality. After the fusion bonding process, the semiconductor chips with the lenses must be removed from the matrix material again. This is associated with a great deal of effort, which leads to very high process and development costs.

[0023] The present optoelectronic component makes use of the idea of ​​attaching an optical element to an optoelectronic semiconductor chip by means of an intermediate layer. By using the intermediate layer, an air gap between the optical element and the optoelectronic semiconductor chip can be avoided. This allows the optical outcoupling to be increased. By applying the lens to a front side of the semiconductor chip, beam shaping in the forward direction can be achieved. This advantageously allows the light extraction of the optoelectronic component to be significantly improved. At the same time, total internal reflection, for example due to a material transition in air, can be reduced when coupling out radiation from the optoelectronic component. The service life of the optoelectronic component can also be advantageously increased.

[0024] According to at least one embodiment of the optoelectronic component, the at least one optical element is designed to shape the beam of radiation from the first wavelength range and / or the second wavelength range. The at least one optical element is, for example, a lens, in particular a converging lens. Radiation from the first wavelength range that is emitted by the optoelectronic semiconductor chip during intended operation is directed, for example, by means of the optical element in the main emission direction. Alternatively or additionally, the optical element acts as a lens for radiation in the second wavelength range that is directed, for example, onto the intermediate layer during manufacture of the optoelectronic component. This radiation is focused, for example, onto the intermediate layer by the optical element.

[0025] Alternatively, the at least one optical element can be a prism. The prism can be used, for example, to influence a main emission direction of the optoelectronic component. This can be particularly advantageous in a case where the at least one optoelectronic semiconductor chip is a laser diode.

[0026] According to at least one embodiment of the optoelectronic component, the at least one optical element and the at least one optoelectronic semiconductor chip are materially connected to one another by means of the intermediate layer. This means in particular that no further material is arranged between the at least one optoelectronic semiconductor chip and the intermediate layer or between the intermediate layer and at least one intermediate element. The intermediate layer preferably borders directly on the at least one optoelectronic semiconductor chip and the at least one optical element. Advantageously, this makes it possible to avoid a material transition to a low-refractive material between the at least one optoelectronic semiconductor chip and the at least one optical element, thus increasing light extraction from the optoelectronic component.According to at least one embodiment of the optoelectronic component, the first wavelength range lies in the UV range of the electromagnetic spectrum and comprises wavelengths greater than or equal to 250 nm. For example, the first wavelength range comprises wavelengths up to and including 380 nm or 300 nm or 280 nm. For example, during intended operation, the optoelectronic component emits radiation with a peak wavelength of 275 nm. The peak wavelength is the wavelength at which an emission spectrum of the optoelectronic component has its greatest intensity. The at least one optoelectronic semiconductor chip is therefore in particular a UV chip, for example a UV sapphire chip.

[0027] According to at least one embodiment of the optoelectronic component, the first wavelength range lies in the UV range of the electromagnetic spectrum and comprises wavelengths greater than or equal to 200 nm. For example, the first wavelength range comprises wavelengths up to and including 380 nm or 300 nm or 280 nm. For example, during intended operation, the optoelectronic component emits radiation with a peak wavelength of 230 nm. The at least one optoelectronic semiconductor chip is therefore, in particular, a UV chip, for example a UV sapphire chip.

[0028] According to at least one embodiment of the optoelectronic component, the second wavelength range comprises wavelengths between 180 nm and 230 nm inclusive, or between 150 nm and 200 nm inclusive. The second wavelength range lies in particular in the UVC range of the electromagnetic spectrum. The second wavelength range preferably comprises shorter wavelengths than the first wavelength range.

[0029] Alternatively, it is possible for the second wavelength range to comprise wavelengths that are longer than wavelengths from the first wavelength range. For example, the second wavelength range comprises wavelengths from the IR range of the electromagnetic spectrum.

[0030] According to at least one embodiment of the optoelectronic component, the at least one optical element has a higher melting point than the intermediate layer. For example, the melting point of the at least one optical element is twice or 1.5 times or 1.3 times as high as a melting point of the intermediate layer. As a result, the intermediate layer between the at least one optoelectronic semiconductor chip and the at least one optical element can be at least partially melted by heating, without the at least one optical element being impaired. A melting point of the intermediate layer is, for example, between 700 °C and 800 °C inclusive. A melting point of the optical element is, for example, more than 1500 °C.

[0031] According to at least one embodiment of the optoelectronic component, the intermediate layer comprises a matrix material in which filler particles are introduced. The filler particles are in particular formed from a material that is transmissive or reflective for radiation from the first wavelength range and absorbent for radiation from the second wavelength range. The matrix material is preferably transmissive for radiation from the first and second wavelength ranges. The matrix material is, for example, a fluoropolymer. The filler particles are, for example, silica particles, also known in English as fused silica.

[0032] According to at least one embodiment of the optoelectronic component, the at least one optical element is a sapphire lens. In the case where the at least one optoelectronic semiconductor chip is a sapphire chip, a sapphire lens is particularly advantageous as the at least one optical element, since the at least one optical element is adapted to the chip substrate of the semiconductor chip, for example with regard to thermal expansion coefficients and / or refractive index.

[0033] According to at least one embodiment of the optoelectronic component, the thermal expansion coefficients of the at least one optical element, the at least one optoelectronic semiconductor chip and the intermediate layer differ from one another by at most 0.5 ppm / K. If the at least one optoelectronic semiconductor chip is, for example, a sapphire chip and, at the same time, the at least one optical element is a sapphire lens, they have the same thermal expansion coefficient. In this case, the thermal expansion coefficients of the at least one optoelectronic semiconductor chip and the at least one optical element are, for example, 7.9 ppm / K.

[0034] Advantageously, the intermediate layer is then adapted such that a thermal expansion coefficient of the intermediate layer differs by at most 0.5 ppm / K from the thermal expansion coefficient of the at least one optoelectronic semiconductor chip and the at least one optical element. For example, in this case, the thermal expansion coefficient of the intermediate layer is 7.7 ppm / K.

[0035] Due to the adapted thermal expansion coefficients of the at least one optoelectronic semiconductor chip, the at least one optical element and the intermediate layer, thermal stress in the optoelectronic component can be reduced.

[0036] According to at least one embodiment, the optoelectronic component comprises a plurality of optoelectronic semiconductor chips in a chip array. Furthermore, the optoelectronic component comprises a plurality of optical elements in a lens array. The chip array and the lens array are positively connected to one another by means of the intermediate layer.

[0037] According to at least one embodiment, the at least one optoelectronic semiconductor chip is arranged on a carrier substrate. A connecting layer is arranged between the carrier substrate and the at least one optoelectronic semiconductor chip. The carrier substrate is formed, for example, from a ceramic. The connecting layer is preferably a solder layer that electrically conductively connects the at least one optoelectronic semiconductor chip to the carrier substrate. The connecting layer comprises, for example, gold and / or tin. In particular, the connecting layer can be formed from AuSn. On a side facing the at least one optoelectronic semiconductor chip, the carrier substrate preferably comprises connection points via which the at least one optoelectronic semiconductor chip can be contacted and supplied with current.On a side opposite the connection points, the carrier substrate comprises, for example, a metallization. In particular, the connection points are electrically connected to the metallization via vias through the carrier substrate. It is possible for the connection points, the vias, and the metallization to be formed integrally and each to comprise at least one metal, such as copper.

[0038] According to at least one embodiment, the optoelectronic component comprises a frame on the carrier substrate. The frame surrounds the at least one optoelectronic semiconductor chip in lateral directions.

[0039] The frame is formed, for example, with a polymer and / or epoxy or alternatively comprises silicon. Lateral directions are, for example, directions that are perpendicular to the main radiation direction.

[0040] The frame is preferably provided with a reflective coating on surfaces facing the optoelectronic semiconductor chip. The surfaces facing the at least one optoelectronic semiconductor chip are preferably inclined. This means that these surfaces have an acute angle with respect to the main extension plane of the active zone. The reflective coating is designed to be reflective for radiation in the first wavelength range and preferably comprises at least one metal, for example aluminum. Radiation that is emitted laterally by the semiconductor chip during intended operation can advantageously be directed in the main emission direction by means of the frame and the reflective coating.

[0041] Furthermore, a method for producing an optoelectronic component is specified. The method can be used, in particular, to produce an optoelectronic component as described herein. This means that all features disclosed for the method are also disclosed for the component, and vice versa.

[0042] In at least one embodiment of the method, at least one optical element is provided in a step A). ​​An intermediate layer is applied to a main surface of the at least one optical element in a step B). The intermediate layer is applied, for example, by dispensing. Alternatively, a material for the intermediate layer can be applied, for example, as a platelet, powder, or paste and then melted. It is also possible for the material for the intermediate layer to be applied by sputtering, vapor deposition, coating, or spraying. At least one optoelectronic semiconductor chip is attached to a side of the intermediate layer facing away from the at least one optical element.

[0043] In a step C) of the method, the at least one optoelectronic semiconductor chip is attached to a side of the intermediate layer facing away from the at least one optical element. In particular, the at least one optical element is placed with the intermediate layer on the at least one optoelectronic semiconductor chip. An adhesion promoter such as glycerol can be used to prevent the at least one semiconductor chip from slipping relative to the at least one optical element. In further method steps, the adhesion promoter is preferably removed again. For example, the adhesion promoter is evaporated.

[0044] In a further step D), the at least one optoelectronic semiconductor chip is connected to the at least one optical element by irradiating the intermediate layer with radiation from a second wavelength range. The at least one optical element is preferably formed from a material that is permeable to radiation from the second wavelength range. Radiation from the second wavelength range is absorbed in the intermediate layer, so that the intermediate layer is heated, at least in places, to a temperature above a melting temperature of the intermediate layer. The intermediate layer advantageously acts like a solder, for example a glass solder.

[0045] In particular, the intermediate layer comprises a material that is absorbent for radiation from the second wavelength range and permeable to radiation from a first wavelength range. Radiation of the first wavelength range is emitted, for example, by the at least one optoelectronic semiconductor chip during normal operation.

[0046] Advantageously, heat is introduced only locally at the intermediate layer during the process, keeping the thermal load during the process relatively low. In particular, the at least one optoelectronic semiconductor chip is heated only slightly. Due to the low thermal load, the overall service life of the optoelectronic component can be increased and the risk of premature damage to the at least one semiconductor chip during component manufacture can be reduced. This increases the service life of the optoelectronic component.

[0047] According to at least one embodiment of the method, in step D), the intermediate layer is irradiated with radiation from the second wavelength range through the optical element. The at least one optical element is configured, for example, to shape the beam of radiation from the second wavelength range. By irradiating the intermediate layer through the at least one optical element, radiation from the second wavelength range can be specifically focused onto the intermediate layer. This can reduce thermal stress on the at least one optoelectronic semiconductor chip and the at least one optical element.

[0048] According to at least one embodiment of the method, laser radiation with a wavelength between 100 nm and 250 nm inclusive, preferably between 120 nm and 230 nm inclusive, is used in step D). A light source for such laser radiation is, for example, an Fg laser, a Xeg laser, a KrCl laser, a KrF laser, or preferably an ArF laser. It is possible for the light source to be operated in a pulsed manner.

[0049] According to at least one embodiment of the method, the at least one optical element has a lateral extent, as viewed onto the main surface, that is greater than a beam width of the laser radiation. The beam width of the laser radiation is measured, for example, perpendicular to a propagation direction of the laser radiation. The lateral extent is, for example, the maximum extent of the at least one optical element in the lateral direction. The lateral extent of the at least one optical element is, for example, between 1000 pm and 6000 pm, for example approximately 2500 pm or approximately 5000 pm. Preferably, in this or in all embodiments, the at least one optical element has a lateral extent that is at least as large as a lateral extent of the main emission surface of the at least one optoelectronic semiconductor chip.In this case, particularly with regard to the main emission surface, this is completely covered by the at least one optical element. A beam width of the laser radiation is, for example, approximately 1740 pm. In particular, the at least one optical element is designed to shape the beam of the laser radiation. The at least one optical element allows the laser radiation to be focused onto the intermediate layer. This makes it possible to reduce thermal stress on the at least one optoelectronic semiconductor chip and the at least one optical element.

[0050] According to at least one embodiment of the method, in step D) the intermediate layer is homogeneously irradiated with the laser radiation. This means in particular that the laser radiation in the region of the intermediate layer has a width that is equal to or greater than a lateral extent of the intermediate layer. The lateral extent of the intermediate layer is measured perpendicular to the direction of propagation of the laser radiation. Advantageously, this allows the intermediate layer to be heated with a single irradiation process and a connection of the at least one optical element to the at least one optoelectronic semiconductor chip is efficiently possible. Alternatively, it is possible for the laser radiation in the region of the intermediate layer to have a beam width that is smaller than the lateral extent of the intermediate layer. In this case, the intermediate layer can be irradiated with the laser radiation in a raster pattern.

[0051] According to at least one embodiment of the method, in step B) the at least one optical element is heated above a melting temperature of the intermediate layer, so that a material of the intermediate layer is evenly distributed over the main surface. The at least one optical element is heated, for example, to at least 700 ° C or at least 800 ° C and at most 900 ° C or at most 1000 ° C. For example, the at least one optical element is heated by means of a heating plate. For example, the at least one optical element is provided on the heating plate. Preferably, the at least one optical element has a higher melting temperature than the intermediate layer. This prevents partial melting of the optical element.

[0052] According to at least one embodiment of the method, before step C), the at least one optoelectronic semiconductor chip is applied to a carrier substrate. During step D), a connecting layer between the carrier substrate and the at least one optoelectronic semiconductor chip is heated to a maximum of 250°C. The connecting layer is, for example, a solder layer. The connecting layer comprises, for example, gold and / or tin or is formed with AuSn. According to at least one embodiment of the method, a plurality of optical elements is provided in a lens array. The intermediate layer is applied to the lens array. The lens array is connected to a chip array which comprises a plurality of optoelectronic semiconductor chips, such that at least one optical element is assigned to each optoelectronic semiconductor chip.It is possible that exactly one optical element is assigned to each optoelectronic semiconductor chip.

[0053] According to at least one embodiment of the method, a composite of the lens array and the chip array is separated into a plurality of optical components.

[0054] Further advantages and advantageous embodiments and further developments of the optoelectronic component and the method will become apparent from the following exemplary embodiments illustrated in conjunction with the schematic drawings. Identical, similar, and similarly acting elements are provided with the same reference symbols in the figures. The figures and the relative sizes of the elements illustrated in the figures are not generally to scale. Rather, individual elements may be exaggerated for clarity and / or comprehensibility.

[0055] It shows :

[0056] Figures 1, 2 and 4 show embodiments of the optoelectronic component in sectional view, Figure 3 shows a detailed view of the intermediate layer according to a

[0057] From example in sectional view,

[0058] Figures 5 to 11 show various process stages of a process for producing an optoelectronic component according to two embodiments in sectional view,

[0059] Figures 12, 13, 15 and 17 are graphic representations of material properties of a material for an intermediate layer according to an embodiment,

[0060] Figure 14 Results of a simulation of the coupling efficiency of an optoelectronic component described here,

[0061] Figure 16 is a graphical representation of material properties of a material for an optical element.

[0062] The optoelectronic component 1 of Figure 1 comprises an optoelectronic semiconductor chip 2 and an optical element 3. An intermediate layer 4 is arranged between the semiconductor chip 2 and the optical element 3.

[0063] The optoelectronic semiconductor chip 2 comprises a semiconductor layer sequence 22. The semiconductor layer sequence 22 is based on a II IV compound semiconductor material.

[0064] The semiconductor layer sequence 22 comprises an active zone (not shown). During normal operation, electromagnetic radiation is generated in the active zone. During normal operation, this electromagnetic radiation is emitted by the optoelectronic semiconductor chip 2 and thus by the optoelectronic component 1. The radiation is radiation from a first wavelength range 5.

[0065] The radiation of the first wavelength range 5 is electromagnetic radiation from the UV range, in particular the UVC range of the electromagnetic spectrum. For example, during normal operation, the optoelectronic component 1 emits radiation with a peak wavelength of 275 nm. The peak wavelength is the wavelength at which an emission spectrum of the optoelectronic component 1 exhibits its greatest intensity.

[0066] The optoelectronic semiconductor chip 2 further comprises a chip substrate 21. The semiconductor layer sequence 22 is applied to the chip substrate 21. The chip substrate 21 is a sapphire substrate. The semiconductor chip 2 is thus a sapphire chip, in particular a volume emitter.

[0067] Contact points 23 for electrically contacting the semiconductor layer sequence 22 are arranged on a side of the semiconductor layer sequence 22 facing away from the chip substrate 21. During normal operation, the semiconductor layer sequence 22 can be energized via the contact points 23. The optoelectronic semiconductor chip 2 is thus a flip chip.

[0068] The intermediate layer 4 is arranged on a side of the chip substrate 21 facing away from the semiconductor layer sequence 22. The intermediate layer 4 comprises a matrix material 41 in which filler particles 42 are embedded. In the present exemplary embodiment, the matrix material 41 is formed from a fluoropolymer. The filler particles 42 are silica particles (see Figure 3).

[0069] The intermediate layer 4 is transparent to radiation from the first wavelength range 5. The intermediate layer 4 is designed to absorb radiation from a second wavelength range 6, which has a different wavelength than the first wavelength range 5. The second wavelength range 6 comprises, for example, shorter wavelengths than the first wavelength range 5. For example, the second wavelength range 6 comprises UV radiation with a wavelength of less than 230 nm. Alternatively, it is also possible for the second wavelength range to have longer wavelengths than the first wavelength range 5. For example, the second wavelength range 6 can comprise radiation in the IR range.

[0070] By irradiating the intermediate layer 4 with radiation of the second wavelength range 6, the optical element 3 can be attached to the semiconductor chip 2. The intermediate layer 4 is heated by absorbing the radiation of the second wavelength range 6, so that a positive connection is created between the semiconductor chip 2 and the optical element 3 (see also Figure 9).

[0071] The intermediate layer 4 has a thickness of between 1 pm and 5 pm inclusive. The thickness of the intermediate layer 4 is selected such that a roughness of a side of the semiconductor chip 2 and / or of the optical element 3 facing the intermediate layer 4 is compensated for. The optical element 3 is designed to shape the beam of radiation in the first wavelength range 5. Radiation can be directed in the direction of a main emission direction 10 by the optical element 3. The main emission direction 10 is preferably perpendicular to a main extension direction of the semiconductor layer sequence 22. Furthermore, it is possible for the optical element 3 to be designed to shape the beam of radiation from the second wavelength range 6 (see Figure 11).

[0072] In the present exemplary embodiment, the optical element 3 is a lens. In the present case, the optical element 3 is formed from sapphire. By using sapphire for the optical element 3 and the chip substrate 21, thermal stresses in the optical component 1 can be reduced. The optical element 3 is transparent to radiation of the first and second wavelength ranges 5, 6. The optical element 3 preferably has a maximum lateral extent of 5000 pm. The lateral extent is measured in a direction parallel to a main extension plane of the semiconductor layer sequence 22.

[0073] Figure 2 shows an optoelectronic component 1 according to a second exemplary embodiment. The optoelectronic component 1 of Figure 2 differs from the optoelectronic component 1 of Figure 1 in that the optoelectronic component 1 of Figure 1 is applied to a carrier substrate 7. The carrier substrate 7 comprises connection points 71 on a side facing the semiconductor chip 2 and a metallization 73 on a side opposite the connection points 71. The metallization 73 is electrically conductively connected to the connection points 71 via vias 72 to the carrier substrate 7. The carrier substrate 7 is formed from a ceramic. The connection points 71, the vias 72 and the metallization 73 each comprise at least one metal, for example copper. The optoelectronic component 1 can be externally contacted and powered via the metallization 73.The connection points, the vias and the metallization 73 can be manufactured in one piece.

[0074] The contact points 23, via which the semiconductor layer sequence 22 can be supplied with current during normal operation, are electrically conductively connected to the connection points 71 by means of a connecting layer 8. The connecting layer 8 is a solder layer, which in particular comprises AuSn.

[0075] The optoelectronic component 1 of Figure 2 further comprises a frame 9. The frame is applied to a main side of the carrier substrate 7 and surrounds the semiconductor chip 2 and the optical element 3 in lateral directions. Lateral directions are directions perpendicular to the main emission direction 10. The frame 9 is formed, for example, with a polymer. For example, the frame is an epoxy potting compound. Alternatively, the frame 9 is a silicon frame adhesively bonded to the carrier substrate 7.

[0076] The frame is provided with a coating 91 on surfaces facing the semiconductor chip 2. These surfaces are inclined and form an acute angle with respect to a main direction of extension of the semiconductor layer sequence 22. The coating 91 is designed to be reflective for radiation from the first wavelength range 5. The coating 91 preferably comprises a metal such as aluminum. The frame 9 with the reflective coating 91 allows the radiation from the first wavelength range 5, which is emitted by the optoelectronic component 1 during normal operation, to be directed in the main emission direction 10.

[0077] In an alternative embodiment, the optoelectronic component 1 does not have a frame 9. In this case, the optoelectronic semiconductor chip 2 is applied to the carrier substrate 7 without being surrounded by a frame 9. In this embodiment, beam shaping and / or directing of the radiation in the main emission direction 10 takes place predominantly or entirely by the optical element 3. In all other aspects, this embodiment corresponds to the embodiment of Figure 2.

[0078] The optoelectronic component 1 of Figure 4 differs from the optoelectronic component of Figure 1 in that the intermediate layer is formed with glass. The glass is transparent to radiation from the first wavelength range 5 and absorbs radiation from the second wavelength range 6. Thus, with regard to the connection of the optoelectronic semiconductor chip 2 and the optical element 3, the intermediate layer 4 of Figure 4 has the same function and properties as the intermediate layer 4 of Figures 1 and 2.

[0079] The intermediate layer 4 is formed with a glass such that a thermal expansion coefficient of the intermediate layer 4 differs from the thermal expansion coefficient of the chip substrate 21 and the optical element 3 by less than 0.5 ppm / K. The thermal expansion coefficient of the chip substrate 21 and the optical element 3 is, for example, 7.9 ppm / K if the material of the chip substrate 21 and the optical element 3 is sapphire. For the intermediate layer 4, for example, a glass which has a thermal expansion coefficient of 7.7 ppm / K is used. The adapted thermal expansion coefficient of the intermediate layer 4 makes it possible to reduce thermal stresses in the optoelectronic component 1.

[0080] Furthermore, the optoelectronic component 1 of Figure 4 differs from the optoelectronic component 1 of Figure 1 in that the optoelectronic component of Figure 4 is applied to a carrier substrate 7. The carrier substrate 7 has, in particular, the same features as the carrier substrate 7 of Figure 2.

[0081] In a first method step in the method for producing an optoelectronic component 1 according to Figures 5 to 11, an optical element 3 is provided (Figure 5). The optical element 3 has, for example, the same properties and features as the optical element 3 of Figure 1. The optical element 3 is provided on a heating plate 101.

[0082] In a subsequent method step, material of the intermediate layer 40 is applied to a main surface 31 of the optical element 3 (Figure 6). The material of the intermediate layer 40 is applied by dispensing. A dispenser 102 is used for this purpose. Alternatively, the material of the intermediate layer 40 can also be applied as a glass platelet, as a paste, or as a powder. It is also possible for the material of the intermediate layer 40 to be applied by sputtering, vapor deposition, coating, or spraying.

[0083] In a further method step, the material of the intermediate layer 40 is evenly distributed over the main surface 31 of the optical element 3 and the intermediate layer 4 is formed (Figure 7). In this method step, the optical element 3 is heated by means of the heating plate 101. The optical element 3 is heated to a temperature which is above a melting temperature of the intermediate layer 4. For example, the optical element 3 is heated to 800°C. The intermediate layer 4 preferably has the same features as the intermediate layer 4 of Figure 4.

[0084] In a subsequent step, the optical element 3 with the intermediate layer 4 is connected to a semiconductor chip 2. The semiconductor chip 2 has, for example, the same features as the semiconductor chip 2 according to Figure 1. The semiconductor chip 2 is provided, for example, on a carrier substrate 7. The carrier substrate 7 preferably has the same features as the carrier substrate 7 of Figure 4.

[0085] To connect the optical element 3 to the semiconductor chip 2, the optical element 3 is placed opposite the semiconductor chip 2. In this case, the optical element 3 is arranged over the semiconductor chip 2 by means of a transfer device 103 (Figure 8). To place the optical element 3, an adhesion promoter (not shown), such as glycerin, can be used. In a process step not shown, the adhesion promoter can be removed again. For example, the adhesion promoter is evaporated.

[0086] Subsequently, the intermediate layer 4 is irradiated with radiation from the second wavelength range 6 (Figure 9). The radiation from the second wavelength range 6 is laser radiation 60. The laser radiation 60 is emitted by a light source 62. The intermediate layer 4 is irradiated through the optical element 3. The light source 62 is, for example, an ArF laser that emits laser radiation 60 with a wavelength of 193.3 nm.

[0087] For example, the laser radiation 60 has a beam width 62 of 1740 pm. The optical element 3 has, for example, a lateral extent of 2500 pm. Both the beam width 62 and the lateral extent of the optical element 3 are measured perpendicular to the propagation direction of the laser radiation 60. The optical element 3 is designed to shape the beam of the laser radiation 60 (Figure 10).

[0088] The laser radiation 60 is absorbed in the intermediate layer 4. As a result, the intermediate layer 4 is heated above its melting temperature and melts. After the intermediate layer 4 has cooled down after the irradiation with the laser radiation 60 has ended, the optoelectronic semiconductor chip 2 and the optical element 3 are positively connected to one another.

[0089] The optical element 3 focuses the laser radiation 60 in the intermediate layer 4 (Figure 10). The laser radiation 60 irradiates a region of the intermediate layer 4 which, in a plan view of the optoelectronic semiconductor chip 2, covers the semiconductor chip 2. This means that the intermediate layer 4 is homogeneously irradiated with the laser radiation 60 in a region in which it borders the semiconductor chip 2. Thus, the intermediate layer 4 can be irradiated in a single irradiation step, and a positive connection between the semiconductor chip 2 and the optical element 3 can be achieved.

[0090] This avoids an air gap between the semiconductor chip 2 and the optical element 3. Furthermore, there is no significant jump in the refractive index between the substrate 21 and the optical element 3, thus increasing the coupling efficiency of the optoelectronic component 1.

[0091] In the method step shown in Figure 11, the method was carried out in a manner different from the method of Figures 5 to 10 in that a lens array 30 is provided, onto which the intermediate layer 4 is applied. The lens array 30 comprises a plurality of optical elements 3. Subsequently, a chip array 20 is applied to the intermediate layer 4 on a side facing away from the lens array 30. The chip array 20 comprises a plurality of optoelectronic semiconductor chips 2.

[0092] Subsequently, a reflective coating 91 is applied to a side of the intermediate layer 4 facing away from the lens array 30, as well as to side surfaces of the optoelectronic semiconductor chips 2. The reflective coating 91 comprises at least one metal, such as aluminum.

[0093] The optoelectronic semiconductor chips 2 are then enclosed using a molding process to produce a carrier substrate 7 .

[0094] In a further method step, the lens array 30 and the chip array 20 are separated along separating lines 75. The separating lines 75 run between the optical elements 3 of the lens region 30. After separation, exactly one optical element 3 is assigned to each optoelectronic semiconductor chip 2.

[0095] Alternatively, the separation step can be omitted, resulting in an optoelectronic component 1 comprising a plurality of optical elements 3 and optoelectronic semiconductor chips 2.

[0096] Figures 12 and 13 show material properties of glasses that can be used for the intermediate layer 4. For example, such glasses are used for the intermediate layer 4 of the optoelectronic component 1 according to Figure 4.

[0097] The glasses 11 to 15 each have a vanishing transmission 50 at a wavelength 51 below 200 nm. The glasses 11 to 15 are therefore not transparent but absorbent in this wavelength range ( Figure 12 ). In a wavelength range with a wavelength 51 greater than 400 nm, all glasses 11 to 15 display a transmission of over 85% up to over 90%. Glass 11 in particular already displays a transmission 50 of almost 90% at a wavelength 51 of approximately 250 nm. The glass 11 is therefore particularly suitable for the intermediate layer 4 because it is transparent at the peak wavelength of the optoelectronic semiconductor chip 2. At the same time, the glass 11 displays an absorption of almost 100% at a wavelength of 193 90 nm, as exhibited, for example, by the second wavelength range 6.

[0098] A thermal expansion coefficient 53 of the glasses 11 to 15 is adapted to the thermal expansion coefficient 53 of sapphire (Figure 13). The difference between the thermal expansion coefficient 53 of the glasses 11 to 15 and the thermal expansion coefficient of sapphire is only 0.2 ppm / K. In comparison, the difference in the thermal expansion coefficient between quartz glass and sapphire is over 7 ppm / K. The glasses 11 to 15 are thus particularly suitable for the intermediate layer to reduce thermal stresses in the optoelectronic component 1.

[0099] Figure 14 shows the results of a simulation in which the outcoupling efficiency is plotted as a function of the refractive index of the optical element and its maximum lateral extension. Generally, the best results are achieved with a lateral extension of the optical element 3 of 2500 pm. The maximum outcoupling efficiency is achieved with a lens material with a refractive index of 1.8. A suitable material for the optical element 3 is therefore sapphire, which has a refractive index of 1.8.

[0100] Figure 15 shows a transmission 50 for a fluoropolymer, such as is used as a matrix material 41 for an intermediate layer 4. Different curves in Figure 15 refer to different fluoropolymer variants, for example to the so-called variants Cytop_ CTL-A, CTX-A and CTX-S. It can be seen that for short-wave radiation with a wavelength 52 of less than 3.5 pm, the transmission 50 is almost 90% for all variants. The fluoropolymer is therefore suitable as a matrix material 41 because it is permeable to radiation from both the first wavelength range and the second wavelength range 6.

[0101] Figure 16 shows the transmission 50 of sapphire in % as a function of the wavelength 52 in pm for various thicknesses. It can be seen that the transmission 50 for wavelengths 52 above 0.2 pm is more than 60% for all thicknesses and for wavelengths 52 above 0.25 pm is more than 90% for all thicknesses. Sapphire is therefore a suitable material for the optical element 3 since it is largely transparent to both radiation from the first wavelength range and radiation from the second wavelength range 6.

[0102] Figure 17 shows a transmission 50 of silica particles in % as a function of the wavelength 52 in pm. This shows that for wavelengths below 0.2 pm the transmission 50 decreases, whereby the absorption increases. In addition, at a wavelength 52 of approximately 2.6 pm the transmission 50 has a local minimum, whereby the absorption at this wavelength 52 has a local maximum. Silica particles are therefore suitable as filler particles 42 in a matrix material 41 for an intermediate layer 4, since the absorption of the silica particles at certain wavelengths can be used to specifically couple heat into the intermediate layer. The invention is not restricted to these by the description based on the exemplary embodiments.Rather, the invention encompasses any new feature and any combination of features, which in particular includes any combination of features in the patent claims, even if this feature or combination itself is not explicitly stated in the patent claims or embodiments.

[0103] This patent application claims priority from German patent application 10 2023 104 440.0, the disclosure of which is hereby incorporated by reference.

[0104] Reference symbol list

[0105] 1 optoelectronic component

[0106] 2 optoelectronic semiconductor chip

[0107] 3 optical element

[0108] 4 Intermediate layer

[0109] 5 first wavelength range

[0110] 6 second wavelength range

[0111] 7 Carrier substrate

[0112] 8 Connection layer

[0113] 9 frames

[0114] 10 Main radiation direction

[0115] 11...15 glass

[0116] 20 chip arrays

[0117] 21 Chip substrate

[0118] 22 semiconductor layer sequence

[0119] 23 Contact point

[0120] 30 lens array

[0121] 31 Main surface of the optical element

[0122] 40 Material of the intermediate layer

[0123] 41 Matrix material

[0124] 42 filler particles

[0125] 50 Transmission in %

[0126] 51 Wavelength in nm

[0127] 52 wavelength in pm

[0128] 53 Thermal expansion coefficient in ppm / K

[0129] 54 refractive index

[0130] 55 Output efficiency

[0131] 60 laser radiation

[0132] 61 beam width

[0133] 62 light source

[0134] 71 Junction

[0135] 72 Through-contacting 73 Metallization

[0136] 75 dividing line

[0137] 91 Coating

[0138] 101 Heating plate 102 Dispenser

[0139] 103 Transfer device

Claims

Patent claims 1. Optoelectronic component (1) comprising - at least one optoelectronic semiconductor chip (2) which is designed to emit radiation in a first wavelength range (5), - at least one optical element (3), and - an intermediate layer (4) between the at least one optoelectronic semiconductor chip (2) and the at least one optical element (3), wherein - the intermediate layer (4) is designed to attach the at least one optoelectronic semiconductor chip (2) to the at least one optical element (3), - the at least one optical element (3) is formed with a material which is permeable to radiation from a second wavelength range (6), - the intermediate layer (4) comprises a material which is permeable to radiation from the first wavelength range (5) and absorbent to radiation from the second wavelength range (6), and - the first wavelength range (5) comprises different wavelengths than the second wavelength range (6).

2. Optoelectronic component (1) according to claim 1, wherein the at least one optical element (3) is designed for beam shaping of radiation from the first wavelength range (5) and / or the second wavelength range (6).

3. Optoelectronic component (1) according to one of the preceding claims, wherein by means of the intermediate layer (4) the at least one optical element (3) and the at least one optoelectronic semiconductor chip (2) are positively connected to one another.

4. Optoelectronic component (1) according to one of the preceding claims, wherein - the first wavelength range (5) comprises wavelengths in the UV range of the electromagnetic spectrum with wavelengths greater than or equal to 250 nm, and - the second wavelength range (6) comprises wavelengths between 180 nm and 230 nm inclusive.

5. Optoelectronic component (1) according to one of claims 1 to 3, wherein - the first wavelength range (5) comprises wavelengths in the UV range of the electromagnetic spectrum with wavelengths greater than or equal to 200 nm, and - the second wavelength range (6) comprises wavelengths between 150 nm and 200 nm inclusive.

6. Optoelectronic component (1) according to one of the preceding claims, wherein the at least one optical element (3) has a higher melting point than the intermediate layer (4).

7. Optoelectronic component (1) according to one of the preceding claims, wherein - the intermediate layer (4) comprises a matrix material (41) in which filler particles (42) are introduced, - the filling particles (42) are formed with a material which is permeable to radiation from the first wavelength range (5) and to radiation from the second wavelength range (6) is absorbing.

8. Optoelectronic component (1) according to one of the preceding claims, wherein the at least one optical element (3) is a sapphire lens.

9. Optoelectronic component (1) according to one of the preceding claims, wherein thermal expansion coefficients of the at least one optical element (3), the at least one optoelectronic semiconductor chip (2) and the intermediate layer (4) differ from one another by at most 0.5 ppm / K.

10. Optoelectronic component (1) according to one of the preceding claims, further comprising: - a variety of optoelectronic semiconductor chips (2) in a chip array (20) , - a plurality of optical elements (3) in a lens array (30), wherein the chip array (20) and the lens array (30) are positively connected to one another by means of the intermediate layer (4).

11. A method for producing an optoelectronic component (1), comprising the following steps: A) Providing at least one optical element (3) , B) Applying an intermediate layer (4) on a main surface (31) of the at least one optical element C) Attaching at least one optoelectronic semiconductor chip (2) to a side of the intermediate layer (4) facing away from the at least one optical element (3), D) connecting the at least one optical element (3) to the at least one optoelectronic semiconductor chip (2) by irradiating the intermediate layer (4) with radiation from a second wavelength range (6), wherein - the at least one optical element (3) is formed with a material which is permeable to radiation from the second wavelength range (6), and - radiation from the second wavelength range (6) is absorbed in the intermediate layer (4), so that the intermediate layer (4) is heated at least in places to a temperature above a melting temperature of the intermediate layer (4).

12. The method according to claim 11, wherein in step D) the intermediate layer (4) is irradiated with radiation from the second wavelength range (6) through the optical element (3).

13. The method according to claim 12, wherein - in step D) laser radiation (60) with a wavelength between 120 nm and 230 nm is used, - the at least one optical element (3) has a lateral extent in view of the main surface (31) which is greater than a beam width (61) of the laser radiation (60), and - the at least one optical element (3) is configured to shape the beam of the laser radiation (60).

14. The method according to claim 13, wherein in step D) the intermediate layer (4) is homogeneously irradiated with the laser radiation (60).

15. The method according to claim 11 to 14, wherein in step B) the at least one optical element (3) is heated above a melting temperature of the intermediate layer (4) so ​​that a material of the intermediate layer (4) is distributed evenly over the main surface (31).

16. Method according to one of claims 11 to 15, in which - before step C) the at least one optoelectronic semiconductor chip (2) is applied to a carrier substrate (7), and - during step D) a connecting layer (8) between the carrier substrate (7) and the at least one optoelectronic semiconductor chip (2) is heated to a maximum of 250 °C.

17. Method according to one of claims 11 to 16, in which - a plurality of optical elements (3) are provided in a lens array (30), - the intermediate layer (4) is applied to the lens array (30), - the lens array (30) is connected to a chip array (20) which comprises a plurality of optoelectronic semiconductor chips (2), so that at least one optical element (3) is assigned to each optoelectronic semiconductor chip (2).

18. The method according to claim 17, wherein a composite of the lens array (30) and the chip array (20) is separated into a plurality of optical components (1).

Images