METHOD FOR PRODUCE A MULTIPLE OF SEMICONDUCTOR LASER CHIP, SEMICONDUCTOR LASER CHIP, METHOD FOR PRODUCE A LASER COMPONENT AND LASER COMPONENT

Abstract

A method for manufacturing a large number of semiconductor laser chips is described, comprising the following steps: - Providing an epitaxial semiconductor layer sequence (2) with an active layer (5) configured to generate electromagnetic radiation on a growth substrate (1), wherein the active layer (5) is arranged between a first semiconductor layer (3) and a second semiconductor layer (4), - Creating a photonic layer (9) with a photonic crystal (10) in the first / second semiconductor layer (3, 4), - Generating recesses (7) starting from a main surface of the epitaxial semiconductor layer sequence (2), wherein the recesses (7) penetrate the active layer (5), - Applying a plurality of first contact points (13) in the recesses (7) that electrically contact the first semiconductor layer (3) and applying a plurality of second contact points (14) over or on the main surface of the epitaxial semiconductor layer sequence (2) that electrically contact the second semiconductor layer (4). Furthermore, a semiconductor laser chip, a method for manufacturing a laser component, and a laser component are specified.

Description

[0001] A method for producing a plurality of photonic surface-emitting semiconductor laser chips, a photonic surface-emitting semiconductor laser chip, a method for producing a laser component, and a laser component are specified.

[0002] The invention aims to provide a simplified method for producing a plurality of photonic surface-emitting semiconductor laser chips. In particular, the method is intended to enable the production of a photonic surface-emitting semiconductor laser chip in a flip-chip design. Furthermore, an improved photonic surface-emitting semiconductor laser chip, in particular in a flip-chip design, is to be provided. Furthermore, a simplified method for producing a laser component and an improved laser component are to be provided.

[0003] These objects are achieved by a method having the steps of patent claim 1, by a photonic surface-emitting semiconductor laser chip having the features of patent claim 10, by a method having the steps of patent claim 16 and by a laser component having the features of patent claim 17.

[0004] Advantageous embodiments and further developments of the two methods, the photonic surface-emitting semiconductor laser chip and the laser component are each specified in the dependent claims.

[0005] According to one embodiment of the method for producing a plurality of photonic surface-emitting semiconductor laser chips, an epitaxial semiconductor layer sequence with an active layer is provided on a growth substrate. The epitaxial semiconductor layer sequence is, in particular, epitaxially grown on the growth substrate and completely covers the growth substrate.

[0006] For example, the epitaxial semiconductor layer sequence and the growth substrate comprise one or more semiconductor materials from the same material system or are formed from one or more semiconductor materials from the same material system. In this case, the lattice constant of the growth substrate and the lattice constant of the epitaxial semiconductor layer sequence are very similar to each other. In particular, the epitaxial semiconductor layer sequence is grown homoepitaxially on the growth substrate.

[0007] According to one embodiment of the method, the growth substrate and the epitaxial semiconductor layer sequence comprise one or more semiconductor materials from the material system of nitride compound semiconductor materials. Nitride compound semiconductor materials are compound semiconductor materials that contain nitrogen, such as the materials from the system In x Al y Ga 1-x-y N with 0 ≤ x ≤ 1, 0 ≤ y ≤ 1 and x+y ≤ 1. For example, the growth substrate comprises GaN or is formed from GaN.

[0008] The active layer is configured to generate electromagnetic radiation. The active layer is arranged between a first semiconductor layer of a first conductivity type and a second semiconductor layer of a second conductivity type. In other words, the epitaxial semiconductor layer sequence comprises the first semiconductor layer, the active layer, and the second semiconductor layer. The first semiconductor layer and the second semiconductor layer are doped according to two different conductivity types. For example, the first semiconductor layer is n-doped and the second semiconductor layer is p-doped, or vice versa. In particular, the first semiconductor layer is arranged closer to the growth substrate than the second semiconductor layer.

[0009] According to a further embodiment of the method, a photonic layer comprising a photonic crystal is produced in the first semiconductor layer and / or the second semiconductor layer. The photonic layer consists, for example, of the photonic crystal.

[0010] Equivalent to the electronic band gap of a semiconductor, the photonic crystal has a band gap for photons, the so-called photonic band gap. Photons with energies within the photonic band gap cannot propagate in the photonic crystal and are reflected by the photonic crystal. The photonic band gap is formed due to periodic structures made of at least two materials that the photonic crystal contains or from which the photonic crystal is formed. The dimension of the photonic crystal is determined by the dimension of the periodicity of the structures. A three-dimensional photonic crystal comprises structures that are periodically continued in three spatial directions. Equivalently, a two-dimensional photonic crystal comprises structures that are periodically formed in two spatial directions.

[0011] For example, the photonic crystal is created by introducing columnar holes in a periodic pattern into the first semiconductor layer and / or the second semiconductor layer, the main extension direction of which runs along a stacking direction of the epitaxial semiconductor layer sequence. The remaining material of the first semiconductor layer and / or the second semiconductor layer, together with the material of the columnar holes, forms, in particular, the photonic crystal. For example, the columnar holes are filled with a gaseous medium, such as air. It is also possible for the columnar holes to be filled with a dielectric material. A refractive index difference between the remaining material of the epitaxial semiconductor layer sequence in the photonic layer and the material of the columnar holes is particularly preferably particularly high in order to achieve the largest possible photonic band gap.

[0012] According to a further embodiment of the method, recesses are created starting from a main surface of the epitaxial semiconductor layer sequence, wherein the recesses penetrate the active layer, in particular completely. In particular, the recesses extend into the first semiconductor layer if this is arranged closer to the growth substrate than the second semiconductor layer. The recesses can be created, for example, by dry-chemical etching.

[0013] According to a further embodiment of the method, a plurality of first electrical contact points are applied in the recesses, which electrically contact the first semiconductor layer. In particular, the first electrical contact points in the recesses are applied in direct contact with the first semiconductor layer.

[0014] According to a further embodiment of the method, a plurality of second electrical contact points are applied above or on the main surface of the epitaxial semiconductor layer sequence, which second electrical contact points electrically contact the second semiconductor layer. In particular, the second electrical contact points are designed to be reflective for the electromagnetic radiation of the active layer. For example, the second electrical contact points comprise silver or are formed from silver. Furthermore, the second electrical contact points can also comprise metal-dielectric mirrors or be formed from metal-dielectric mirrors. For example, the second electrical contact points are applied in direct contact with the second semiconductor layer.If the photonic crystal is incorporated into the second semiconductor layer, it is also possible for the second electrical contact points to be applied in direct contact with the photonic layer and the photonic crystal.

[0015] The term "over or on" is intended to emphasize that the two elements thus placed in relation to each other do not necessarily have to be in direct physical contact. Rather, additional elements may be arranged between them.

[0016] In particular, a solder layer can also be applied to the first electrical contact points and / or the second electrical contact points.

[0017] The method for producing the plurality of photonic surface-emitting semiconductor laser chips comprises in particular the following steps: - Providing the epitaxial semiconductor layer sequence with the active layer, which is configured to generate electromagnetic radiation, on the growth substrate, wherein the active layer is arranged between the first semiconductor layer of the first conductivity type and the second semiconductor layer of the second conductivity type, - producing the photonic layer with the photonic crystal in the first semiconductor layer and / or in the second semiconductor layer, - Creating the recesses starting from the main surface of the epitaxial semiconductor layer sequence, wherein the recesses penetrate the active layer, - Applying the plurality of first electrical contact points in the recesses, which electrically contact the first semiconductor layer, - Applying the plurality of second electrical contact points above or on the main surface of the epitaxial semiconductor layer sequence, which electrically contact the second semiconductor layer.

[0018] In particular, the steps are carried out in the order given.

[0019] In particular, the growth substrate is a wafer and the epitaxial semiconductor layer sequence is a semiconductor layer sequence with a large number of connected semiconductor layer stacks, from which many separate photonic surface-emitting semiconductor laser chips are later created.

[0020] The present method is, in particular, a wafer-level method in which the process steps are performed on a wafer composite, thereby producing a plurality of identical photonic surface-emitting semiconductor laser chips. In particular, the growth substrate and the epitaxial semiconductor layer sequence are present as a wafer composite.

[0021] The present method is used, in particular, to produce photonic surface-emitting semiconductor laser chips in flip-chip design, in which first electrical contact points and second electrical contact points are arranged on or above the same main surface of the epitaxial semiconductor layer sequence.

[0022] According to one embodiment of the method, a further layer is applied to the photonic layer before the first electrical contact points and the second electrical contact points are applied. For example, the further layer is a further semiconductor layer, which preferably has the same conductivity type as the semiconductor material of the photonic layer. In particular, the further semiconductor layer has the second conductivity type of the second semiconductor layer. In particular, the further semiconductor layer is p-doped. Furthermore, it is also possible for the further layer to have a TCO (short for “transparent conductive oxide”), for example ITO (short for “indium tin oxide”), or to consist of a TCO, such as ITO. In particular, the further layer is electrically conductive.

[0023] According to a further embodiment of the method, insulation layers are arranged on side surfaces of the recesses. Considering a single recess, for example, the first electrical contact point extends completely over a bottom surface of the recess and a side surface of the recess facing away from the photonic layer, up to an adjacent part of the main surface of the epitaxial semiconductor layer sequence. For example, the insulation layer covers the side surface of the recess that is not covered by the first electrical contact point. Preferably, the insulation layer completely covers the photonic layer that is exposed on the side surface of the recess. The insulation layers can be applied to the side surfaces of the recesses directly after they have been created or at any later time.

[0024] According to a further embodiment of the method, the insulation layers are arranged between the first electrical contact points and the second electrical contact points. In particular, an insulation layer electrically insulates a first electrical contact point and a directly adjacent second electrical contact point from each other. In particular, the insulation layer is electrically insulating. For example, the insulation layer comprises a dielectric material or is formed from a dielectric material.

[0025] According to a further embodiment of the method, a sacrificial layer is applied over or on the first electrical contact points and the second electrical contact points, wherein the sacrificial layer has a plurality of openings that completely penetrate the sacrificial layer. For example, the sacrificial layer comprises a metal or a dielectric, such as SiO2, or is formed from a metal or a dielectric, such as SiO2.

[0026] According to a further embodiment of the method, a planarization layer is applied to the sacrificial layer, wherein a material of the planarization layer fills the openings. In particular, the material of the planarization layer completely fills the openings. The planarization layer is, in particular, completely applied to the sacrificial layer. The planarization layer can, in particular, comprise a polymer or consist of a polymer, such as benzocyclobutene (BCB). For example, the planarization layer is applied using a spin-coating process.

[0027] According to a further embodiment, a carrier wafer is applied over or on the planarization layer. For example, the carrier wafer is attached to the planarization layer by adhesive bonding or soldering. For example, the carrier wafer comprises or is formed from one of the following materials: silicon, germanium, sapphire.

[0028] According to a further embodiment of the method, the sacrificial layer is removed in places, so that the material of the planarization layer forms connecting elements in the apertures that mechanically connect the epitaxial semiconductor layer sequence to the carrier wafer. In particular, after removal of the sacrificial layer, the epitaxial semiconductor layer sequence is mechanically connected to the carrier wafer only by the connecting elements.

[0029] For example, the sacrificial layer is removed using dry chemical methods, such as a reactive gas mixture that selectively dissolves the sacrificial layer. It is also possible to remove the sacrificial layer using wet chemical methods. In this case, a protective layer is preferably applied over the first electrical contact points and the second electrical contact points before removing the sacrificial layer.

[0030] The present method is, in particular, a so-called "coupon method," in which the subsequently fully processed photonic surface-emitting semiconductor laser chips are provided on the carrier wafer, to which the finished photonic surface-emitting semiconductor laser chips are mechanically connected via the connecting elements. The connecting elements are comparatively small, so that the photonic surface-emitting semiconductor laser chips can be easily detached from the carrier wafer at a later time, for example, with the aid of a stamp, and transferred to another element, such as a connection carrier.

[0031] According to a further embodiment of the method, a plurality of recesses are created in the epitaxial semiconductor layer sequence, such that the sacrificial layer is accessible through the recesses. In particular, two directly adjacent recesses each define an epitaxial semiconductor layer stack, which is part of a finished photonic surface-emitting semiconductor laser chip. The recesses in the epitaxial semiconductor layer sequence are created, for example, by dry-chemical etching.

[0032] According to a further embodiment of the method, the growth substrate is thinned or completely removed from the epitaxial semiconductor layer sequence. The thinning of the growth substrate or the removal of the growth substrate is carried out, for example, by etching, grinding, and / or polishing. If the growth substrate is thinned, the remaining thickness of the thinned growth substrate is, for example, between 1 micrometer and 50 micrometers, or between 1 micrometer and 20 micrometers, or between 1 micrometer and 10 micrometers.

[0033] According to a further embodiment of the method, the photonic layer is created in the second semiconductor layer before the first electrical contact points and the second electrical contact points are applied to the epitaxial semiconductor layer sequence. In this embodiment, the wafer composite is mechanically stabilized, in particular, only by the growth substrate. In particular, no carrier wafer has yet been attached to the epitaxial semiconductor layer sequence.

[0034] According to a further embodiment of the method, the photonic layer is created in the first semiconductor layer after the first electrical contact points and the second electrical contact points have been applied to the epitaxial semiconductor layer sequence. The first semiconductor layer is arranged closer to the growth substrate than the second semiconductor layer. In this embodiment, in particular, the carrier wafer is attached to the epitaxial semiconductor layer sequence, and the growth substrate is completely removed, so that the first semiconductor layer is freely accessible in order to create the photonic crystal in the first semiconductor layer.

[0035] In particular, the photonic layer with the photonic crystal does not need to be closed in this embodiment of the method. In other words, the structures in the first semiconductor layer for forming the photonic crystal, such as the columnar recesses, do not need to be filled with additional material. If the first semiconductor layer is an n-doped semiconductor layer, the production of the photonic crystal in this semiconductor layer is advantageous because a better current distribution can be achieved during operation of the subsequent photonic surface-emitting semiconductor laser chip than in the p-doped semiconductor layer, and thus a reduced current flow through the semiconductor material due to the photonic crystal is not significant.

[0036] According to a further embodiment of the method, the growth substrate is removed before the photonic layer is produced.

[0037] The method is designed to produce at least one photonic surface-emitting semiconductor laser chip. In particular, the method provides a wafer assembly comprising a plurality of photonic surface-emitting semiconductor laser chips connected to a carrier wafer, in particular by connecting elements. Therefore, all features and embodiments described in connection with the method for producing a photonic surface-emitting semiconductor laser chip can also be implemented in the photonic surface-emitting semiconductor laser chip, and vice versa.

[0038] According to one embodiment, the photonic surface-emitting semiconductor laser chip comprises an epitaxial semiconductor layer stack having an active zone arranged between a first semiconductor layer of a first conductivity type and a second semiconductor layer of a second conductivity type, wherein the active zone generates electromagnetic laser radiation during operation.

[0039] As already described above, a large number of recesses are created in the epitaxial semiconductor layer sequence, through which the epitaxial semiconductor layer sequence is separated into epitaxial semiconductor layer stacks. In particular, the part of the active layer located in an epitaxial semiconductor layer stack is referred to below as the active zone. In other words, the active zone was part of the active layer before the recesses were introduced into the epitaxial semiconductor layer sequence. In contrast, the terms for the first semiconductor layer and the second semiconductor layer are retained, even though in an epitaxial semiconductor layer stack only a part of the first semiconductor layer and a part of the second semiconductor layer of the epitaxial semiconductor layer sequence are present. The same applies to the photonic layer and the photonic crystal.

[0040] According to a further embodiment, the photonic surface-emitting semiconductor laser chip comprises a photonic layer with a photonic crystal arranged in a near field of the electromagnetic laser radiation generated in the active zone. In particular, the photonic surface-emitting semiconductor laser chip is a PCSEL (short for "photonic surface-emitting semiconductor laser").

[0041] In particular, the photonic crystal generates an increased photonic density of states in the active zone, so that electromagnetic laser radiation is generated in the active zone upon electrical pumping. The active zone is optically coupled to the photonic crystal, so that at least one evanescent wave of the modes of the electromagnetic laser radiation propagates in the photonic crystal. For example, the active zone is separated from the photonic crystal only by a thin, charge-carrier-blocking layer. In particular, the active zone is arranged in a near field of the photonic crystal. This results in emission, in particular, in the modes of the photonic crystal.

[0042] According to a further embodiment, the photonic surface-emitting semiconductor laser chip comprises a first electrical contact point and a second electrical contact point above or on a main surface of the epitaxial semiconductor layer stack.

[0043] In particular, a recess is arranged at least partially between the first electrical contact point and the second electrical contact point. For example, the recess extends annularly around a radiation exit surface of the photonic surface-emitting semiconductor laser chip. It is also possible for the recess to be in the form of contact fingers that extend entirely or partially over the radiation exit surface.

[0044] Furthermore, an insulating layer is preferably arranged between the first electrical contact point and the second electrical contact point. For example, the insulating layer is applied to a side surface of the recess. The insulating layer preferably electrically insulates the first electrical contact point from the second electrical contact point.

[0045] A radiation exit surface of the photonic surface-emitting semiconductor laser chip is formed, in particular in plan view, completely or partially overlapping with the first electrical contact point.

[0046] According to a further embodiment of the photonic surface-emitting semiconductor laser chip, the photonic crystal is a two-dimensional photonic crystal that contributes to the formation of electromagnetic laser radiation in the active zone.

[0047] According to a further embodiment, the photonic surface-emitting semiconductor laser chip comprises a first mounting surface and a second mounting surface located in the same plane. In particular, the photonic surface-emitting semiconductor laser chip is a flip-chip semiconductor chip. In particular, the first electrical contact point and the second electrical contact point are arranged above or on the same main surface of the epitaxial semiconductor layer stack. This simplifies the mounting of the photonic surface-emitting semiconductor laser chip to a further element, such as an electrical connection carrier.

[0048] For example, a first outer surface of the first electrical contact point forms the first mounting surface, and an outer surface of the second electrical contact point forms the second mounting surface of the photonic surface-emitting semiconductor laser chip. Furthermore, it is also possible for a solder layer to be applied above or on the first electrical contact point and above or on the second electrical contact point, forming the first mounting surface and / or the second mounting surface.

[0049] According to a further embodiment of the photonic surface-emitting semiconductor laser chip, the first electrical contact point is annular in plan view and arranged at a distance around the second electrical contact point, which is preferably round, in particular circular. A first electrical contact point arranged annularly in plan view around a second round electrical contact point has, in particular, improved switching times due to the geometry.

[0050] If the first electrical contact point is arranged in a ring shape in plan view at a distance around the second, round electrical contact point, it is possible for the ring-shaped first electrical contact point to have an opening that breaks through the ring-shaped first electrical contact point. This can improve the solderability of the photonic surface-emitting semiconductor laser chip, since no joining material, such as solder, is enclosed by the ring-shaped first electrical contact point. Excess joining agent can escape through the opening under the photonic surface-emitting semiconductor laser chip during the joining process.

[0051] According to a further embodiment of the photonic surface-emitting semiconductor laser chip, a radiation exit surface of the photonic surface-emitting semiconductor laser is circular in plan view and covered by the second circular electrical contact point. In particular, the second circular electrical contact point injects current into the region of the epitaxial semiconductor layer stack that overlaps in plan view, so that electromagnetic laser radiation is generated there.

[0052] The present photonic surface-emitting semiconductor laser chip is configured for use in a method for manufacturing a laser component. Consequently, all features and embodiments disclosed in connection with the photonic surface-emitting semiconductor laser chip are also disclosed in the methods for manufacturing the laser component, and vice versa.

[0053] According to one embodiment of the method for producing a laser component, a plurality of photonic surface-emitting semiconductor laser chips are provided, as already described. The photonic surface-emitting semiconductor laser chips are mechanically connected to a carrier wafer by connecting elements. In particular, the photonic surface-emitting semiconductor laser chips are mechanically connected to the carrier wafer only via the connecting elements. For example, each photonic surface-emitting semiconductor laser chip is mechanically connected to the carrier wafer by at least three connecting elements.

[0054] According to a further embodiment of the method for producing the laser component, at least one photonic surface-emitting semiconductor laser chip is transferred from the carrier wafer to a connection carrier, for example, using a stamp, in particular a silicone stamp. The connection of the photonic surface-emitting semiconductor laser chip to the carrier wafer via the connecting elements is weaker than the connection of the photonic surface-emitting semiconductor laser chip to the stamp. With the aid of the stamp, the connecting elements are mechanically released, for example, broken, so that the photonic surface-emitting semiconductor laser chip adheres to the stamp and can be transferred to another element, such as a connection carrier.

[0055] In particular, the method for manufacturing the laser component comprises the following steps: - Providing the plurality of photonic surface-emitting semiconductor laser chips that are mechanically connected to the carrier wafer by the connecting elements, and - Transferring at least one photonic surface-emitting semiconductor laser chip from the carrier wafer to the connection carrier.

[0056] In particular, the steps are carried out in the specified order.

[0057] With the specified method, it is particularly possible to produce laser components with a large number of photonic surface-emitting semiconductor laser chips arranged at a small distance from one another.

[0058] The following describes a laser component as it can be manufactured using the method for manufacturing the laser component. Therefore, all features and configurations described in connection with the method for manufacturing the laser component can also be implemented in the laser component, and vice versa.

[0059] According to one embodiment, the laser component comprises a photonic surface-emitting semiconductor laser chip, as has already been described in particular above.

[0060] According to a further embodiment, the laser component comprises a connection carrier with a first electrical connection point and a second electrical connection point. For example, the connection carrier is a printed circuit board (PCB). The connection carrier can also be another semiconductor chip, for example, a silicon semiconductor chip, or a photonic integrated circuit (PIC).

[0061] According to a further embodiment of the laser component, the first electrical contact point of the photonic surface-emitting semiconductor laser chip is electrically conductively and mechanically stably connected to the first electrical connection point of the connection carrier, and the second electrical contact point of the photonic surface-emitting semiconductor laser chip is electrically conductively and mechanically stably connected to the second electrical connection point of the connection carrier, for example by soldering.

[0062] For example, the first electrical contact point and the first electrical connection point have the same geometry. Furthermore, it is also possible for the second electrical contact point of the photonic surface-emitting semiconductor laser chip and the second connection point of the connection carrier to have the same geometry. In particular, the second electrical connection point of the connection carrier is preferably also round, in particular circular, if the second electrical contact point of the photonic surface-emitting semiconductor laser chip is round, in particular circular. Likewise, the first electrical connection point of the electrical connection carrier is preferably annular if the first electrical contact point of the photonic surface-emitting semiconductor laser chip is annular.The relative arrangement of the first electrical connection point of the connection carrier and the second electrical connection point of the connection carrier to one another is also preferably designed to be identical to the arrangement of the first electrical contact point and the second electrical contact point.

[0063] According to a further embodiment of the laser component, the second connection point is round, in particular circular, in plan view, and the first connection point is arranged in a ring at a distance around the second round connection point. Furthermore, the first connection point and the second connection point are connected, in particular directly, to conductor tracks on the connection carrier. In particular, the photonic surface-emitting semiconductor laser chip in this case is designed in a flip-chip design, so that electrical contact with the connection carrier can be established via the same side of the photonic surface-emitting semiconductor laser chip.

[0064] Since the photonic surface-emitting semiconductor laser chip is designed as a flip-chip, comparatively flat laser components can be produced. Furthermore, bond wires can be omitted for the electrical contacting of the photonic surface-emitting semiconductor laser chip, thus achieving lower induction and shorter switching times of the laser component.

[0065] Furthermore, it is advantageously possible to mount large-area optical elements directly onto the photonic surface-emitting semiconductor laser chip connected to the connection carrier, since interfering bond wires are eliminated. In particular, additional optical elements are mounted above or on the radiation exit surface of the photonic surface-emitting semiconductor laser chip after connecting the photonic surface-emitting semiconductor laser chip to a connection carrier. This prevents the optical elements from being exposed to damaging elevated temperatures during the bonding process.

[0066] Furthermore, the light from the photonic surface-emitting semiconductor laser chip can also be coupled directly into an optical fiber, especially one with large cross-sections. Furthermore, a medium for adjusting the refractive index can be inserted between the optical element and / or the optical fiber.

[0067] Further advantageous embodiments and developments of the photonic surface-emitting semiconductor laser chip, the two methods and the laser component emerge from the exemplary embodiments described below in conjunction with the figures.

[0068] The Fig. 1 to 9 show schematic sectional views of stages of a method for producing a plurality of photonic surface-emitting semiconductor laser chips according to an embodiment.

[0069] The Fig. 10 to 12 show schematic sectional views of stages of a method for producing a plurality of photonic surface-emitting semiconductor laser chips according to a further embodiment.

[0070] The Fig. 13 shows a schematic sectional view of a photonic surface-emitting semiconductor laser chip as part of a wafer assembly according to an embodiment.

[0071] The Fig. 14 to 16 show schematic sectional views of stages of a method for producing a laser component according to an embodiment.

[0072] The Fig. 17 and Fig. 18 shows a schematic sectional view of a laser component according to one embodiment.

[0073] The Fig. 19 and Fig. 20 show schematic plan views of a connection carrier according to two different embodiments.

[0074] Identical, similar, or functionally identical elements are provided with the same reference numerals in the figures. The figures and the relative sizes of the elements depicted in the figures are not to be considered to scale. Rather, individual elements, particularly layer thicknesses, may be exaggerated for clarity and / or clarity.

[0075] In the method for producing a plurality of photonic surface-emitting semiconductor laser chips according to the embodiment of the Fig. 1 to 9, an epitaxial semiconductor layer sequence 2 is first provided, which is epitaxially grown on a growth substrate 1.

[0076] The epitaxial semiconductor layer sequence 2 is based on a nitride compound semiconductor material and is, for example, epitaxially grown on a gallium nitride growth substrate (see Fig. 1).

[0077] The epitaxial semiconductor layer sequence 2 comprises a first semiconductor layer 3 of a first conductivity type and a second semiconductor layer 4 of a second conductivity type. In this case, the first semiconductor layer 3 is n-doped, while the second semiconductor layer 4 is p-doped. The n-doped first semiconductor layer 3 is arranged closer to the growth substrate 1 than the p-doped second semiconductor layer 4. An active layer 5 is arranged between the first semiconductor layer 3 and the second semiconductor layer 4, which is configured to generate electromagnetic radiation.

[0078] The growth substrate 1 and the epitaxial semiconductor layer sequence 2 are provided as a wafer composite 6 and further processed in subsequent steps to produce a plurality of photonic surface-emitting semiconductor laser chips in parallel process steps. For reasons of clarity, however, only the production of a single photonic surface-emitting semiconductor laser chip is shown in the figures.

[0079] Starting from a main surface of the epitaxial semiconductor layer sequence, recesses 7 are created in the epitaxial semiconductor layer sequence 2. The recesses 7 penetrate the active layer 5 completely ( Fig. 2). In other words, the recesses 7 expose the first semiconductor layer 3. In the present case, the recesses 7 are arranged in a ring around central regions 8 of the epitaxial semiconductor layer sequence 2. The recesses 7 can also be formed as a contact finger structure to enable the best possible current distribution in the active layer 5.

[0080] Then, a photonic layer 9 with a two-dimensional photonic crystal 10 is created in the second semiconductor layer 4. In particular, the photonic layer is created in the central region 8, which is delimited by the recess 7, in the second semiconductor layer 4. The photonic crystal 10 has columnar holes 11 arranged perpendicular to the main surface of the epitaxial semiconductor layer sequence 2. The columnar holes 11 in the second semiconductor layer 4 are arranged in a periodic pattern to form the two-dimensional photonic crystal 10. In particular, the photonic layer 9 with the photonic crystal 10 is arranged so close to the active layer 5 that the photonic crystal 10 is arranged in the finished semiconductor laser chip in an evanescent field of the electromagnetic radiation generated in the active layer 5. ( Fig. 2)

[0081] In a next step, a further layer 12 is applied to the photonic layer 9 in the central region 8. For example, the further layer 12 is grown epitaxially and also comprises a p-doped nitride compound semiconductor material or consists of a p-doped nitride compound semiconductor material, such as p-GaN. Furthermore, it is also possible for the further layer 12 to comprise a TCO, such as ITO, or to be formed from a TCO ( Fig. 3).

[0082] In a further step, first electrical contact points 13 and second electrical contact points 14 are applied to the wafer composite 6. The first electrical contact points 13 are applied in the recesses 7 and extend over a bottom surface 15 of the recesses 7, across a side surface 16, to a region of the main surface of the epitaxial semiconductor layer sequence 2 that faces away from the central region 8. The first electrical contact points 13 electrically contact, in particular, the first semiconductor layer 3. The first electrical contact points 13 are in direct contact with the first semiconductor layer 3, at least in the recesses 7 and on the bottom surfaces 15 of the recesses 7. The second electrical contact points 14 are applied in direct contact with the further layer 12 in the central region 8 of the epitaxial semiconductor layer sequence 2.In particular, the second electrical contact points 14 electrically contact the second semiconductor layer 4.

[0083] Insulation layers 17 are arranged between the first electrical contact points 13 and the second electrical contact points 14 ( Fig. 4). The insulation layers 17 are, in particular, directly adjacent to the first electrical contact points 13 and the second electrical contact points 14. In particular, the insulation layer 17 electrically insulates the directly adjacent first electrical contact point 13 and the directly adjacent second electrical contact point 14 from one another and covers the side surface 16' of the recess 7, preferably completely. The insulation layers 17 can also be applied to the side surfaces of the recesses directly after the creation of the recesses or at another time after the creation of the recesses.

[0084] In a next step, a sacrificial layer 18 is applied to the wafer composite 6 over the main surface of the epitaxial semiconductor layer sequence 2. The sacrificial layer 18 has a plurality of openings 19 that completely penetrate the sacrificial layer 18. In the present case, the sacrificial layer 18 is applied directly onto the first electrical contact points 13 and the second electrical contact points 14, as well as the insulation layers 17, completely covering them. For example, the sacrificial layer 18 comprises a dielectric or a metal.

[0085] Then, a planarization layer 20 is applied in direct contact with the sacrificial layer 18. The planarization layer 20 completely fills the openings 19. For example, the planarization layer 20 is formed from a polymer such as BCB ( Fig. 5).

[0086] Then, a carrier wafer 21 is mechanically stably attached to the planarization layer 20 by means of a joining layer 22, for example a solder layer ( Fig. 6).

[0087] The growth substrate 1 is thinned, for example by grinding ( Fig. 7). The thinned growth substrate 1 has a thickness of several micrometers, for example. This is sufficient for good current distribution in the first semiconductor layer 3. Alternatively, the growth substrate 1 can also be completely removed. In this case, the epitaxial semiconductor layer sequence 2 is exposed. An electrically conductive layer, for example, comprising a TCO such as ITO or consisting of a TCO such as ITO, can be applied to the epitaxial semiconductor layer sequence 2 for current injection.

[0088] In a next step, recesses 24 are introduced into the wafer assembly 6 starting from the thinned growth substrate 1 along a growth direction of the epitaxial semiconductor layer sequence 2 up to the sacrificial layer 18 ( Fig. 8). The recesses 24 completely penetrate the growth substrate 1 and the epitaxial semiconductor layer sequence 2. In particular, the sacrificial layer 18 is at least partially exposed by the recesses 24.

[0089] The recesses 24 define epitaxial semiconductor layer stacks 25, which later become part of a finished photonic surface-emitting semiconductor laser chip.

[0090] Then the sacrificial layer 18 is removed ( Fig. 9), for example, by wet or dry chemical etching. After the removal of the sacrificial layer 18, the epitaxial semiconductor layer stacks 25, which are formed by the recesses 24, are mechanically connected to the carrier wafer 21 via the material of the planarization layer 22 in the openings 19 of the sacrificial layer 18. In particular, the material of the planarization layer 22 forms connecting elements 23 in the openings 19 (see Fig. 9).

[0091] There is now a wafer assembly 6 in which a plurality of photonic surface-emitting semiconductor laser chips are mechanically connected to the carrier wafer 21 via the connecting elements 23.

[0092] In the method according to the embodiment of the Fig. 10 to 12, an epitaxial semiconductor layer sequence 2 is first provided, as already shown in FIG. Fig. 1. However, no photonic layer 9 with a photonic crystal 10 is introduced into the second semiconductor layer 4, as can be seen from Fig. 2. Rather, a plurality of recesses 7 are introduced into the epitaxial semiconductor layer sequence 2, which completely penetrate the active layer 5, so that the first semiconductor layer 3 is exposed at a bottom surface 15 of the recesses 7. Then, first electrical contact points 13, second electrical contact points 14 and insulation layers 17 between the first electrical contact points 13 and the second electrical contact points 14 are applied to the epitaxial semiconductor layer sequence 2, as shown in FIG. Fig. 4 described.

[0093] In a further step, a sacrificial layer 18 with openings 19 is arranged above or on the epitaxial semiconductor layer sequence 2. In this case, the sacrificial layer 18 is arranged in direct contact with the first electrical contact points 13 and the second electrical contact points 14, as well as the insulation layers 17.

[0094] A planarization layer 20 is applied to the sacrificial layer 18. The planarization layer 20 completely fills the recesses 7 in the epitaxial semiconductor layer sequence 2 and the openings 19 in the sacrificial layer 18.

[0095] A carrier wafer 21 is attached to the planarization layer 20 by means of a joining layer 22, for example a solder layer. The wafer composite 6 thus produced is Fig. 10 shown.

[0096] In a next step, the growth substrate 1 is completely removed from the wafer assembly 6. After removing the growth substrate 1, the first semiconductor layer 3 of the first conductivity type is freely accessible ( Fig. 11). The first semiconductor layer 3 is n-doped.

[0097] Then, a photonic layer 9 with a photonic crystal 10 is introduced into the first semiconductor layer 3 ( Fig. 12). The photonic crystal 10 is formed, for example, as shown in Fig. 2 already described.

[0098] Then, recesses 24 are introduced into the epitaxial semiconductor layer sequence 2 in order to produce the plurality of epitaxial semiconductor layer stacks 25 and to partially expose the sacrificial layer 18, as already shown in the Fig. 8 described ( Fig. 12).

[0099] Then, the sacrificial layer 18 is removed, so that a plurality of photonic surface-emitting semiconductor laser chips is formed, which are mechanically connected to the carrier wafer 21 by connecting elements 23 formed from the material of the planarization layer 20 ( Fig. 13).

[0100] In the method according to the embodiment of the Fig. 10 to 12, the photonic layer 9 is, in contrast to the method according to the embodiment of Fig. 1 to 9 are introduced into the first semiconductor layer 3 and not into the second semiconductor layer 4. For this purpose, the growth substrate 1 is completely removed after the carrier wafer 21 has been attached, so that the first semiconductor layer 3 is freely accessible for structuring with the photonic crystal 10. In other words, the photonic crystal 10 is introduced into the second semiconductor layer 4 at a different time than into the first semiconductor layer 3.

[0101] Fig. Figure 13 shows the photonic surface-emitting semiconductor laser chip, which is mechanically connected to the carrier wafer 21 via a connecting element 23. The photonic surface-emitting semiconductor laser chip has an epitaxial semiconductor layer stack 25 with an active zone 26 arranged between a first semiconductor layer 3 of a first conductivity type and a second semiconductor layer 4 of a second conductivity type. In this case, the first semiconductor layer 3 is n-doped, and the second semiconductor layer 4 is p-doped. The active zone 26 is suitable for generating electromagnetic laser radiation during operation.

[0102] Furthermore, the photonic surface-emitting semiconductor laser chip comprises a photonic layer 9 with a two-dimensional photonic crystal 10 arranged in a central region 8 of the epitaxial semiconductor layer stack 25. The central region 8 is delimited by a recess 7 that breaks through the active zone 26. The recess 7 is round in plan view and surrounds the central region 8. During operation, the photonic surface-emitting semiconductor laser chip emits electromagnetic laser radiation from a radiation exit surface 27, which is also delimited by the recess 7.

[0103] The photonic crystal 10 is arranged in a near field of the electromagnetic laser radiation. An evanescent field of the electromagnetic laser radiation generated in the active zone 26 during operation optically couples to the photonic crystal 10 of the photonic layer 9. The photonic crystal 10 acts as an optical cavity of the photonic surface-emitting semiconductor laser chip to form electromagnetic laser radiation generated by stimulated emission. In particular, the photonic crystal 10 causes the electromagnetic radiation generated in the active zone 26 to be emitted in the modes of the photonic crystal 10.

[0104] The photonic surface-emitting semiconductor laser chip is a flip-chip in which a first electrical contact point 13, which electrically contacts the first semiconductor layer 3 in the recess 7, and a second electrical contact point 14, which electrically contacts the second semiconductor layer 4, are arranged on one side of the photonic surface-emitting semiconductor laser chip. A first mounting surface 37 of the photonic surface-emitting semiconductor laser chip is surrounded by an outer surface of the first electrical contact point 13, and a second mounting surface 38 of the photonic surface-emitting semiconductor laser chip is surrounded by an outer surface of the second electrical contact point 14. The first mounting surface 37 and the second mounting surface 38 lie in a common plane E.

[0105] In the method for producing a laser component according to the embodiment of the Fig. 14 to 16, a wafer assembly 6 is first provided, as is the case, for example, with the method according to the embodiment of the Fig. 10 to 12. A plan view of the wafer assembly 6 is shown in Fig. 14. Here, a plurality of photonic surface-emitting semiconductor laser chips 28 are provided, which are mechanically connected to a carrier wafer 21 via connecting elements 23 (not shown).

[0106] Furthermore, a connection carrier 29 is provided, which is shown schematically in Fig. 15 is shown in plan view. The connection carrier 29 is intended to accommodate a photonic surface-emitting semiconductor laser chip 28. For this purpose, the connection carrier 29 has a first electrical connection point 30 and a second electrical connection point 31. The first electrical connection point 30 is annular, while the second electrical connection point 31 is round and extends at a distance around the second electrical connection point 30.

[0107] In particular, in the present embodiment, the first electrical contact point 13 of the photonic surface-emitting semiconductor laser chip 28 to be applied is geometrically identical to the first electrical connection point 30 of the connection carrier 29. The second electrical contact point 14 of the photonic surface-emitting semiconductor laser chip 28 is also geometrically identical to the second electrical connection point 14 of the connection carrier 29.

[0108] A photonic surface-emitting semiconductor laser chip 28 is removed from the carrier wafer 21 by means of a stamp 32 ( Fig. 16) and transferred to the connection carrier 29. The photonic surface-emitting semiconductor laser chip 28 is mechanically removed from the carrier wafer 21 using the stamp 32, releasing the connecting elements 23, and adheres to the stamp 32.

[0109] For example, the surface-emitting photonic semiconductor laser chip 28 with the first electrical contact point 13 and the second electrical contact point 14 is soldered to the first electrical connection point 30 and the second electrical connection point 31 of the connection carrier 29.

[0110] The laser component according to the embodiment of the Fig. 17 is, for example, with the method according to the embodiment of the Fig. 14 to 16 produced.

[0111] The laser component according to Fig. 17 comprises a photonic surface-emitting semiconductor laser chip 28, such as is used in connection with the method according to Fig. 10 to 12. The photonic surface-emitting semiconductor laser chip 28 has a photonic layer 9 with a photonic crystal 10, which is incorporated into a first semiconductor layer 3 of an epitaxial semiconductor layer stack 25. The first semiconductor layer 3 has a first conductivity type. In the present case, the first semiconductor layer is n-doped.

[0112] The photonic surface-emitting semiconductor laser chip 28 is mechanically and electrically connected to a connection carrier 29 via a solder layer (not shown). In particular, a first electrical contact point 13 of the photonic surface-emitting semiconductor laser chip 28 is soldered to a first connection point 30 of the connection carrier 29, and a second electrical contact point 14 of the photonic surface-emitting semiconductor laser chip 28 is soldered to a second connection point 31 of the connection carrier 29.

[0113] The laser component according to the embodiment of the Fig. 18 has a photonic surface-emitting semiconductor laser chip 28, such as can be produced by the method according to Fig. 1 to 9. The photonic surface-emitting semiconductor laser chip 28 has a photonic layer 9 with a photonic crystal 10, which is incorporated into the second semiconductor layer 4.

[0114] Furthermore, the laser component according to the embodiment of the Fig. 18 has a connection carrier 29 which comprises a first electrical connection point 30 and a second electrical connection point 31 and to which the photonic surface-emitting semiconductor laser chip 28 is connected in a mechanically stable and electrically conductive manner.

[0115] During operation of the laser component, the photonic surface-emitting semiconductor laser chip 28 emits electromagnetic laser radiation from a radiation exit surface 27. Since a main surface of the photonic surface-emitting semiconductor laser chip 28, which comprises the radiation exit surface 27, is free of bond wires, the electromagnetic laser radiation 33 emitted from the radiation exit surface 27 can be coupled directly into an optical fiber 34 or an optical element. The optical element and / or the optical fiber 34 can be arranged at a distance from the radiation exit surface 27 of the photonic surface-emitting semiconductor laser chip 28 by an air gap 35. The air gap 35 can be filled with a material that matches the refractive index of the two directly adjacent materials.

[0116] The connection carrier 29 according to the embodiment of the Fig. 19 can, for example, in the method according to the embodiment of the Fig. 14 to 16 can be used.

[0117] The connection carrier 29 according to the Fig. 19 has, in contrast to the connection carrier 29 of the Fig. 15 has a first annular electrical connection point 30 with an opening 35. A connection carrier 29 with such a geometry of the first connection point 30 and the second connection point 31 can be connected to a photonic surface-emitting semiconductor laser chip 28 particularly easily by soldering, since air is not trapped inside the first annular electrical connection point 30, but can escape through the opening 35.

[0118] The connection carrier 29 according to the embodiment of the Fig. 20 can be used in the method according to the embodiment of the Fig. 14 to 16. In contrast to the connection carrier 29 according to the embodiment of the Fig. 19, the connection carrier 29 comprises, in addition to the first electrical connection point 30 and the second electrical connection point 31, conductor tracks 36 which are directly conductively connected to the first electrical connection point 30 and the second electrical connection point 31.

[0119] In particular, a conductor track 36 extends from the first electrical connection point 30 through an opening 35 of the annular first electrical connection point 30. Parallel to this, further conductor tracks 36 run which are connected to the annular first electrical connection point 30.

[0120] The invention is not limited to the embodiments by the description. Rather, the invention encompasses any novel feature and any combination of features, including, in particular, 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. List of reference symbols 1 growth substrate 2 epitaxial semiconductor layer sequence 3 first semiconductor layer 4 second semiconductor layer 5 active layer 6 wafer composite 7 Recess 8 central area 9 photonic layer 10 photonic crystal 11 columnar hole 12 additional layers 13 first electrical contact point 14 second electrical contact point 15 Bottom surface of the recess 16, 16' side surface of the recess 17 Insulation layer 18 sacrificial layer 19 Breakthrough 20 Planarization layer 21 carrier wafers 22 Joining layer 23 Connecting element 24 recess 25 epitaxial semiconductor layer stack 26 active zones 27 Radiation exit surface 28 semiconductor laser chip 29 connection carriers 30 first electrical connection point 31 second electrical connection point 32 stamps 33 electromagnetic laser radiation 34 optical fibers 35 Opening 36 conductor track 37 first assembly area 38 second mounting surface E Level

Claims

[1] A method for producing a plurality of photonic surface-emitting semiconductor laser chips (28) comprising the following steps: - Providing an epitaxial semiconductor layer sequence (2) with an active layer (5) which is designed to generate electromagnetic radiation on a growth substrate (1), wherein the active layer (5) is arranged between a first semiconductor layer (3) of a first conductivity type and a second semiconductor layer (4) of a second conductivity type, - producing a photonic layer (9) with a photonic crystal (10) in the first semiconductor layer (3) or in the second semiconductor layer (4), - producing recesses (7) starting from a main surface of the epitaxial semiconductor layer sequence (2), wherein the recesses (7) penetrate the active layer (5), - applying a plurality of first electrical contact points (13) in the recesses (7) which electrically contact the first semiconductor layer (3), - Applying a plurality of second electrical contact points (14) above or on the main surface of the epitaxial semiconductor layer sequence (2), which electrically contact the second semiconductor layer (4). [2] Method according to the preceding claim, wherein insulation layers (17) are arranged on side surfaces (16') of the recesses (7). [3] Method according to the preceding claim, wherein the insulation layers (17) are arranged between the first electrical contact points (13) and the second electrical contact points (14). [4] Method according to one of the preceding claims, comprising the further steps: - applying a sacrificial layer (18) over or on the first electrical contact points (13) and the second electrical contact points (14), wherein the sacrificial layer (18) has a plurality of openings (19) which completely penetrate the sacrificial layer (18), and - applying a planarization layer (20) on the sacrificial layer (18), wherein a material of the planarization layer (20) fills the openings (19). [5] Method according to the preceding claim, comprising the further steps: - applying a carrier wafer (21) over or on the planarization layer (20), and - removing the sacrificial layer (18) so that the material of the planarization layer (20) forms connecting elements (23) in the openings (19) which mechanically connect the epitaxial semiconductor layer sequence (2) to the carrier wafer (21). [6] Method according to one of claims 4 to 5, wherein a plurality of recesses (24) are produced in the epitaxial semiconductor layer sequence (2) so that the sacrificial layer (18) is accessible through the recesses (24). [7] Method according to one of the preceding claims, wherein the photonic layer (9) is produced (4) in the second semiconductor layer before the first electrical contact points (13) and the second electrical contact points (14) are applied to the epitaxial semiconductor layer sequence (2). [8] Method according to one of the preceding claims, wherein the photonic layer (9) is produced after the application of the first electrical contact points (13) and the second electrical contact points (14) to the epitaxial semiconductor layer sequence (2) in the first semiconductor layer (3). [9] Method according to the preceding claim, in which the growth substrate (1) is removed before the photonic layer (9) is produced. [10] Photonic surface-emitting semiconductor laser chip (28) comprising: - an epitaxial semiconductor layer stack (25) comprising an active zone (26) arranged between a first semiconductor layer (3) of a first conductivity type and a second semiconductor layer (4) of a second conductivity type, wherein the active zone (26) generates electromagnetic laser radiation (33) during operation, - a photonic layer (9) with a photonic crystal (10) arranged in a near field of the electromagnetic laser radiation (33) generated in the active zone (26), and - a first electrical contact point (13) and a second electrical contact point (14) above or on a main surface of the epitaxial semiconductor layer stack (25). [11] Photonic surface-emitting semiconductor laser chip (28) according to the preceding claim, wherein the photonic crystal (10) is a two-dimensional photonic crystal (10) which contributes to the formation of electromagnetic laser radiation (33) in the active zone (26). [12] Photonic surface emitting semiconductor laser chip (28) according to one of claims 10 to 11, further comprising a first mounting surface (37) and a second mounting surface (38) lying in a same plane (E). [13] Photonic surface-emitting semiconductor laser chip (28) according to one of claims 10 to 12, wherein the first electrical contact point (13) is arranged in a ring shape at a distance around the second electrical contact point (14) in plan view. [14] Photonic surface-emitting semiconductor laser chip (28) according to the preceding claim, wherein the annular first electrical contact point (13) has an opening (35) which breaks through the annular first electrical contact point (13). [15] Photonic surface-emitting semiconductor laser chip (28) according to one of claims 13 to 14, wherein a radiation exit surface (27) of the photonic surface-emitting semiconductor laser chip (28) is round in plan view and is covered by the second electrical contact point (14). [16] A method for manufacturing a laser component comprising the following steps: - Providing a plurality of photonic surface-emitting semiconductor laser chips (28) according to one of claims 10 to 15, which are mechanically connected to a carrier wafer (21) by connecting elements (23), and - Transferring at least one photonic surface-emitting semiconductor laser chip (28) from the carrier wafer (21) to a connection carrier (29). [17] Laser component with: - a photonic surface-emitting semiconductor laser chip (28) according to one of claims 10 to 15, and - a connection carrier (29) with a first electrical connection point (30) and a second electrical connection point (31), wherein the first electrical contact point (13) of the photonic surface-emitting semiconductor laser chip (28) is electrically conductively and mechanically stably connected to the first electrical connection point (30) of the connection carrier (29) and the second electrical contact point (14) of the photonic surface-emitting semiconductor laser chip (28) is electrically conductively and mechanically stably connected to the second electrical connection point (31) of the connection carrier (29). [18] Laser component according to the preceding claim, wherein - the second electrical connection point (31) is round in plan view, and - the first electrical connection point (30) is arranged in a ring shape at a distance around the round second electrical connection point (31), and - the first electrical connection point (30) and the second electrical connection point (31) are connected to conductor tracks (36) on the connection carrier (29).

Images