Laser device and method

Abstract

The invention relates to an optoelectronic laser device comprising: a semiconductor layer stack having an active zone which is provided between a first layer of a first conductivity type and a second layer of a second conductivity type, at least one structure which is designed to constrict the current in the active zone for generating a laser radiation, and a first front face, which extends from a first upper face in the direction of a first lower face lying opposite the first upper face and has an exit window for the laser radiation generated in the active zone; a support substrate having an electrical via extending from a second upper face to a second lower face lying opposite the second upper face, and a second front face extending from the second lower face in the direction of the second upper face, wherein the second front face has a first portion adjoining the second upper face and a second portion set back from the first portion; and an electrical contact layer which is provided on the first lower face and is designed to be positioned on a contact element and which is electrically connected to the first layer. The first upper face and the second lower face are located next to each other in a contacting manner, and the electrical via is electrically connected to the second layer.

Description

[0001] LASER DEVICE AND METHOD

[0002] This application claims priority from German patent application No. 10 2024 103 984 . 1 filed on February 13, 2024, the disclosure of which is hereby incorporated by reference into this application.

[0003] The present invention relates to a laser device and a method for producing a laser device.

[0004] BACKGROUND

[0005] Laser diodes, and in particular high-power laser diodes, require good heat dissipation in order to achieve their full optical performance. To date, laser diodes have usually been mounted on a target substrate with their growth substrate side facing down, or they have been mounted on a heat sink with a high thermal conductivity with the side opposite the growth substrate side facing down. However, since both cases result in a long heat path between the laser diode and the target substrate (through the entire growth substrate or through passivation layers on the surface of the laser diode and the entire heat sink), and since the output power of laser diodes is constantly increasing, there is a need to specify an optoelectronic laser device with reduced thermal resistance, and a method for producing such an optoelectronic laser device which counteracts at least one of the aforementioned problems.

[0006] SUMMARY OF THE INVENTION

[0007] This need is met by the subject matter of the independent patent claims. Further developments and embodiments of the proposed principle are specified in the subclaims.

[0008] The core idea of ​​the invention is to provide a method with which it is possible to thin an edge-emitting laser diode or the semi-semiconductor body of the laser diode at wafer level from the growth substrate side in such a way that the laser diode can be applied to a target substrate essentially directly, without further passivation layers etc. and with the shortest possible heat path. For this purpose, during production at wafer level, a carrier substrate is applied to a side opposite the growth substrate, which fixes the semiconductor body and enables the semiconductor body to be thinned from the growth substrate side.Subsequently separated laser devices consisting of the thinned semiconductor body and part of the carrier substrate have only a thin residual region of the semiconductor body between a mounting side and the active zone, in which the heat is generated when laser radiation is generated, so that the heat path between the semiconductor body and the target substrate on which the laser device is mounted with the mounting side is as short as possible. The carrier substrate remains on the semiconductor body in the separated laser device and, due to the preceding manufacturing steps, has a corresponding characteristic shape in order to provide an exposed light exit window for the laser radiation generated in the semiconductor body and to prevent beam clipping of the laser radiation emitted from the light exit window.Compared to existing methods for fabricating edge-emitting lasers, the proposed method is not limited to a minimum thickness of the semiconductor body to enable stable production. However, applying the semiconductor body to a secondary substrate prior to singulating individual laser devices allows for further processing of the semiconductor body beyond the limits of the state of the art.

[0009] The invention offers, among other things, a solution to the requirement for a short thermal path and correspondingly improved thermal performance. Furthermore, the proposed laser device can reduce electrical losses within the laser device and correspondingly improve the system performance of an arrangement comprising the proposed laser device. Furthermore, the proposed method enables the use of mass production processes to ensure reduced costs for manufacturing a proposed laser device.

[0010] According to a first aspect, an optoelectronic laser device is specified. The optoelectronic laser device comprises a semiconductor layer stack with an active zone, which is arranged between a first layer of a first conductivity type and a second layer of a second conductivity type, and at least one structure which is designed to constrict current in the active zone in order to generate laser radiation. In addition, the semiconductor layer stack comprises a first front side, which extends from a first top side in the direction of a first bottom side opposite the first top side and has an exit window for the laser radiation generated in the active zone. The semiconductor layer stack can in particular be designed in the form of an edge-emitting laser diode, and the exit window can in particular be referred to as a laser facet and can adjoin the active zone on the first front side.

[0011] The optoelectronic laser device further comprises a carrier substrate with an electrical via extending from a second upper side to an opposite second lower side, and a second front side extending from the second lower side toward the second upper side. The second front side has a first section adjoining the second upper side and a second section set back from the first section, so that the second front side is, in particular, step-shaped, at least in some regions.

[0012] Furthermore, an electrical contact layer is arranged on the first underside, which is designed to be arranged on a contact element and which is in electrical connection with the first layer. In particular, the optoelectronic laser device can be subjected to a first electrical potential for generating laser radiation via the electrical contact layer. The semiconductor layer stack and the carrier substrate are arranged relative to one another or next to one another in such a way that the first upper side and the second underside touch one another. In addition, the semiconductor layer stack and the carrier substrate are arranged or designed in such a way that the electrical via is in electrical connection with the second layer. In particular, the optoelectronic laser device can be subjected to a second electrical potential for generating laser radiation via the electrical via.

[0013] The thermal performance of the proposed laser device can be improved in particular by the fact that the semiconductor body of the laser device can be applied with its growth substrate side directly onto a target substrate, however, in contrast to known solutions with a significantly reduced thickness between the electrical contact layer and the active zone for generating laser radiation. This is achieved by thinning the semiconductor body, which in turn is only made possible by using the carrier substrate, which is applied to the semiconductor layer sequence before singulation of individual laser devices at wafer level. In addition, parasitic electrical path(s) can be reduced by thinning the semiconductor body and removing a growth substrate as well as applying the electrical contact layer.Reducing the thermal path ( e ) and the series resistance leads to a significant improvement in the efficiency of the laser device. Furthermore, wafer-level processing enables a cost-effective approach to fabricating the laser device.

[0014] With the help of etched facet technology to create the exit window for the laser radiation generated in the active zone and with the help of a pre-structured carrier substrate comprising an electrical through-contact(s). e.g. SiC with through-contacts, or Si with a through-silicon via (TSV). A singulated chip-scale package (CSP) can also be achieved for applications that require a laser device that emits laser radiation to the side. The etched facet technology for creating the exit window and the pre-structured carrier substrate enable the exit window to be created at wafer level and the laser device to be singulated without damaging the created exit window.

[0015] According to at least one embodiment, the first front side has a third section adjoining the first underside and a fourth section set back with respect to the third section, so that the first front side is also designed, in particular, to be step-shaped, at least in some regions. In particular, the fourth section of the first front side of the semiconductor layer stack, which is set back with respect to the third section, has the exit window. In particular, the fourth section can extend through the second layer, the active zone and into the first layer, whereas the third section can extend only through the first layer of the semiconductor layer stack.The step shape can in particular result from two separate structuring steps, wherein a first structuring step is provided in order to produce the exit window, so that the fourth section of the first front side is created, and a second structuring step serves to separate the laser device, so that the third section of the first front side is created.

[0016] According to at least one embodiment, the second section and the first front side, and in particular the fourth section of the first front side, lie substantially in the same plane. In particular, a region of the first front side that has the exit window and the second section of the second front side of the carrier substrate that is set back relative to the first section can lie substantially in the same plane.

[0017] According to at least one embodiment, the first section of the second front side of the carrier substrate and the third section of the first front side lie substantially in the same plane. In particular, a region of the first front side that does not have the exit window and the first section of the second front side of the carrier substrate can lie substantially in the same plane.

[0018] According to at least one embodiment, the active zone is arranged between two waveguide layers. In particular, the active zone can be arranged between two layers with a lower refractive index than the material of the active zone, so that an optical wave generated in the active zone is guided along the active zone. Due to the differences in refractive index and the associated total reflection, the two waveguide layers and the active zone can together form a waveguide along which the optical wave propagates before it can be coupled out via the exit window adjacent to the active zone.

[0019] According to at least one embodiment, the at least one structure which is designed for current constriction in the active zone for generating laser radiation is formed, for example, by a strip contact (gain guide) on the second layer or by structuring (index guide, by ridge etching or lateral mixing of the second layer). In particular, the structure for current constriction can be designed such that current injection takes place only in a narrow region of the active zone, which is adjoined by the exit window, so that an optical wave is formed in this region and propagates along the active zone and in particular along the narrow region.For this purpose, a highly reflective mirror can also be provided on a first rear side of the semiconductor layer stack opposite the first front side and in particular directly opposite the exit window, which mirror reflects an optical wave propagating between the exit window and the highly reflective mirror in the direction of the exit window. The exit window can furthermore be designed to be partially reflective, as is already known from commercial edge-emitting laser diodes. The aforementioned structure can provide a so-called laser channel in the laser device. According to at least one embodiment, the fourth section is formed by a first recess in the semiconductor layer stack, which extends from the first top side in the direction of the first bottom side.Additionally or alternatively, the second portion may be formed by a second recess in the carrier substrate, which extends from the second bottom side towards the second top side.

[0020] The first recess can extend over the entire width of the first top side when viewed in plan view of the first top side, or can be formed, for example, by a pocket in the semiconductor layer stack which, when viewed in plan view of the first top side, does not extend over the entire width of the first top side, but in particular over at most 200 μm of the width of the first top side. The first front side can accordingly have a region in the form of the fourth section which, when viewed in plan view of the first top side, extends over the entire width of the first top side, or which, when viewed in plan view of the first top side, does not extend over the entire width of the first top side.In the latter case, the first front side in particular may have a region in the form of the third section which, viewed in plan view of the first front side, borders the fourth region on three sides and is correspondingly U-shaped viewed in plan view of the first front side and borders the fourth region on three sides.

[0021] Alternatively or additionally, the second recess can extend over the entire width of the second underside when viewed in plan view of the second underside, or it can be formed, for example, by a pocket in the carrier substrate which, when viewed in plan view of the second underside, does not extend over the entire width of the second underside, but in particular over at most 200 μm of the width of the second underside. The second front side can accordingly have a region in the form of the second section which, when viewed in plan view of the second underside, extends over the entire width of the second underside, or which, when viewed in plan view of the second underside, does not extend over the entire width of the second underside.In the latter case, the second front side in particular may have a region in the form of the first section which, viewed in plan view of the second front side, borders the second region on three sides and is correspondingly U-shaped viewed in plan view of the second front side and borders the second region on three sides.

[0022] According to at least one embodiment, the semiconductor layer stack has a thickness of at most 50 pm, in particular at most 30 pm, or at most 15 pm. Thanks to such a small thickness, in combination with the electrical contact layer arranged on the first underside, which is designed to be arranged on a contact element, a heat path between the active zone, in which heat is generated during the generation of laser radiation, and a target substrate can be as small as possible, so that the thermal power of the laser device is increased.

[0023] According to at least one embodiment, the active zone is arranged at a closer distance to the first upper side than to the first lower side. In particular, this can achieve the result that the remaining first layer, together with the electrical contact layer, acts as a type of submount, so that beam clipping of a laser radiation emitted from the exit window is prevented. However, the position of the active zone relative to the first lower side or the first upper side can also be varied, in particular by varying the degree of thinning of the semiconductor layer stack.

[0024] According to at least one embodiment, the fourth section is set back from the third section by at most 100 pm, and in particular by at least 10 pm. Additionally or alternatively, the second section can be set back from the first section by at most 100 pm, and in particular by at least 10 pm. The depth of the second or fourth section relative to the first or third section can in particular be selected to be large enough that, on the one hand, damage to the exit window is prevented when the laser device is separated, but at the same time can be selected to be small enough that beam clipping of laser radiation emitted from the exit window is prevented.

[0025] According to at least one embodiment, the semiconductor layer stack further comprises a first rear side opposite the first front side, which extends from the first upper side toward the first lower side. The first rear side can be configured to correspond to the first front side and, for example, can comprise a fifth section adjoining the first lower side and a sixth section set back from the fifth section.

[0026] According to at least one embodiment, the carrier substrate further comprises a second rear side opposite the second front side, which extends from the second upper side toward the second lower side. The second rear side can be configured to correspond to the second front side and, for example, comprise a seventh section adjoining the second upper side and an eighth section set back from the seventh section.

[0027] According to at least one embodiment, the semiconductor layer stack has a multiplicity of structures which are designed to constrict current in the active zone for generating laser radiation. At the same time, the semiconductor layer stack has, on its first front side, a multiplicity of exit windows which are arranged downstream of the active zone in a region of a respective current constriction. In each case, a structure which is designed to constrict current in the active zone for generating laser radiation, in interaction with an exit window, can form, in particular, a laser channel in the semiconductor layer stack. Accordingly, the laser device can have not only one laser channel, but also a plurality of laser channels which are formed adjacent to one another in the laser device in the semiconductor layer stack.

[0028] The exit windows can be formed in a continuous first front side, in a common section of the first front side, or in separate sections of the first front side. For example, the exit windows can each be exposed through a separate pocket in the semiconductor layer stack, a first number of exit windows can be exposed through a first pocket and another number of exit windows can be exposed through a second pocket, or all exit windows can be exposed through a common pocket or recess.

[0029] The structures designed to constrict current in the active zone for generating laser radiation can, for example, be formed by individual strip contacts on the second layer or by structuring the second layer. Furthermore, the electrical contact layer arranged on the first underside can be formed by several separate contact layers in order to be able to control the individual laser channels separately, or it can be formed by a common contact layer that contacts all laser channels simultaneously.

[0030] According to at least one embodiment, the electrical via extends substantially centrally through the carrier substrate and correspondingly contacts substantially centrally the second layer or the structure which is designed to constrict the current in the active zone for generating laser radiation. The via can be formed, for example, by a TSV. However, the via can also be formed by an opening through the carrier substrate, the inner wall of which is coated with an electrically conductive material. For example, the electrical via can also be formed in an edge region of the carrier substrate and, for example, be formed only by a cylinder segment which extends from the second top side to the second bottom side.This can occur, for example, because before a separation of several laser devices, an electrical via for several adjacent laser devices may have been provided through the carrier substrate, which is separated during the separation.

[0031] According to at least one embodiment, the semiconductor layer stack comprises gallium nitride (GaN) or gallium arsenide (GaAs) or consists largely of GaN or GaAs. In particular, the semiconductor layer stack can comprise indium aluminum gallium arsenide (InAlGaAs) or indium gallium nitride (InGaN) substrate. Other possible materials for the semiconductor layer stack can be aluminum nitride or gallium arsenide.

[0032] According to at least one embodiment, the carrier substrate comprises a ceramic material and / or a semiconductor material such as Si or SiC.

[0033] Furthermore, a method for producing a laser device is specified. In particular, a laser device as described here can be produced by means of the method. This means that all features disclosed for the laser device are also disclosed for the method, and vice versa.

[0034] A method for manufacturing a laser device according to another aspect comprises the following steps:

[0035] Providing a semiconductor layer stack (with an active zone arranged between a first layer of a first conductivity type and a second layer of a second conductivity type, and at least one structure designed to constrict current in the active zone for generating laser radiation;

[0036] Creating at least one first recess in the semiconductor layer stack such that a fourth section of a first front side of the semiconductor layer stack is exposed, which section extends from a first top side of the semiconductor layer stack through the second layer, the active zone and into the first layer, and which exposes an exit window for the laser radiation generated in the active zone;

[0037] Providing a carrier substrate having an electrical via extending from a second top side to an opposite second bottom side, and at least one second recess extending from the second bottom side toward the second top side and exposing a second portion of a second front side;

[0038] Applying the first upper side to the second lower side such that the first upper side and the second lower side are arranged touching one another, the electrical via is in electrical connection with the second layer, and the first and second recesses are substantially opposite one another;

[0039] Thinning the semiconductor layer stack such that a first bottom side of the semiconductor layer stack opposite the first top side is exposed; and

[0040] Applying an electrical contact layer to the first underside , which is in electrical connection with the first layer and which is designed to be arranged on a contact element .

[0041] According to at least one embodiment, the first and the second recess are substantially identically dimensioned, and the step of applying the first upper side to the second lower side is carried out in such a way that the first and the second recess are substantially congruent with one another.

[0042] According to at least one embodiment, the step of thinning the semiconductor layer stack is carried out in such a way, and in particular to such a depth, that the at least one first recess is opened from a side opposite the first top side. Accordingly, the step of thinning the semiconductor layer stack can be carried out in such a way that any material of the first layer between the first bottom side and the first recess is removed.

[0043] According to at least one embodiment, the step of thinning the semiconductor layer stack is carried out such that the remaining semiconductor layer stack has a thickness of at most 50 pm, in particular at most 30 pm, or at most 15 pm.

[0044] According to at least one embodiment, the method further comprises severing at least the carrier substrate in the region of the at least one second recess, wherein the severing exposes a first portion of the second front side, which extends from the second top side toward the second bottom side, and wherein the second portion is set back from the first portion. The severing step can in particular be a singulation step between a plurality of laser devices arranged side by side.

[0045] According to at least one embodiment, the step of severing comprises severing the semiconductor layer stack in the region of the at least one first recess, wherein the severing of the semiconductor layer stack exposes a third section of the first front side, which extends from the first underside in the direction of the first top side, and wherein the fourth section is set back relative to the third section.

[0046] According to at least one embodiment, the step of applying the first upper side to the second lower side is carried out in such a way that the at least one first recess and the at least one second recess are substantially congruent with one another, in particular in such a way that the second section and the fourth section lie substantially in the same plane.

[0047] The first recess can extend over the entire width of the first top side when viewed in plan view of the first top side, in particular in the form of a trench, or can be formed, for example, by one or more pockets in the semiconductor layer stack which, when viewed in plan view of the first top side, do not extend over the entire width of the first top side, but rather in particular over at most 200 pm of the width of the first top side.

[0048] Alternatively or additionally, the second recess can extend over the entire width of the second underside when viewed in plan view of the second underside, in particular in the form of a trench, or it can be formed, for example, by one or more pockets in the carrier substrate which, when viewed in plan view of the second underside, do not extend over the entire width of the second underside, but in particular each over at most 200 pm of the width of the second underside.

[0049] According to at least one embodiment, the step of providing the semiconductor layer stack comprises providing the semiconductor layer stack with a large number of structures which are designed to constrict current in the active zone in order to generate laser radiation. In addition, the method comprises generating a large number of first recesses in the semiconductor layer stack such that a large number of fourth sections of first front sides of the semiconductor layer stack are exposed, which sections each extend from a first top side of the semiconductor layer stack through the second layer, the active zone and into the first layer, and which each expose at least one exit window for the laser radiation generated in the active zone.Furthermore, the step of providing the carrier substrate comprises providing the carrier substrate with a plurality of second recesses that extend from the second bottom side toward the second top side and expose a plurality of second portions of second front sides, wherein the carrier substrate has a plurality of electrical vias that extend from the second top side to the second bottom side. In particular, the method can be used to produce a plurality of laser devices simultaneously at the wafer level and / or laser devices with more than one laser channel.

[0050] According to at least one embodiment, a plurality of laser devices are separated by means of the severing step, each of which comprises at least one of the plurality of current constriction structures and one of the plurality of exit windows and each of which comprises at least one electrical via that is in electrical connection to a partial region of the second layer.

[0051] BRIEF DESCRIPTION OF THE DRAWINGS Further aspects and embodiments according to the proposed principle will become apparent with reference to the various embodiments and examples which are described in detail in conjunction with the accompanying drawings.

[0052] Fig. 1A to 1D show steps of a method for manufacturing a laser device according to the proposed principle;

[0053] Fig. 2A to 2C each show a plan view of a bottom side of a laser device according to the proposed principle;

[0054] Fig. 3 shows a sectional view of a laser device according to the proposed principle mounted on a target substrate;

[0055] Fig. 4A to 4D show steps of another method for manufacturing a laser device according to the proposed principle;

[0056] Fig. 5 shows a sectional view of another embodiment of a laser device according to the proposed principle mounted on a target substrate;

[0057] Fig. 6A to 6E show steps of a further method for producing a laser device according to the proposed principle as well as detailed views of the semiconductor layer stack;

[0058] Fig. 7A to 7G show a step of a further method for producing a laser device according to the proposed principle, as well as detailed views of the carrier substrate; Fig. 8A to 8D show steps of a further method for producing a laser device according to the proposed principle, as well as detailed views of the semiconductor layer stack;

[0059] Fig. 9A to 9E show a step of another method for

[0060] Manufacture of a laser device according to the proposed principle and detailed views of the carrier substrate.

[0061] DETAILED DESCRIPTION

[0062] The following embodiments and examples show various aspects and their combinations according to the proposed principle. The embodiments and examples are not always true to scale. Likewise, various elements can be shown enlarged or reduced in size to emphasize individual aspects. It goes without saying that the individual aspects and features of the embodiments and examples shown in the figures can be combined with one another without thereby impairing the inventive principle. Some aspects have a regular structure or shape. It should be noted that in practice slight deviations from the ideal shape can occur without, however, contradicting the inventive idea.

[0063] Furthermore, the individual figures, features, and aspects are not necessarily shown in the correct size, and the proportions between the individual elements may not always be correct. Some aspects and features are emphasized by being shown enlarged. However, terms such as "top", "above", "below", "below", "larger", "smaller", and the like are correctly represented with reference to the elements in the figures. This makes it possible to infer such relationships between the elements from the illustrations.

[0064] Figures 1A to 1D show steps of a method for manufacturing a laser device 1 according to the proposed principle. The left-hand part of the figures shows a schematic sequence at the wafer level, while the right-hand part of the figures shows a sectional view of the intermediate products of the method.

[0065] In a first step, a semiconductor layer stack 2 is provided with an active zone arranged between a first layer of a first conductivity type and a second layer of a second conductivity type. In addition to the layer sequence not shown in detail, the semiconductor layer stack 2 has a plurality of structures designed to constrict current in the active zone for generating laser radiation.The step further comprises creating first cutouts 15a in the semiconductor layer stack 2 such that a fourth section 13d of first front sides of the semiconductor layer stack 2 of laser devices formed later and an opposite sixth section 13f of first rear sides of the semiconductor layer stack 2 of laser devices formed later are exposed, which extend from a first top side 8a of the semiconductor layer stack 2 through the second layer, the active zone and into the first layer. In addition, the first cutouts 15a each expose at least one exit window (not shown in detail here) for laser radiation generated in the active zone, which exit windows are each arranged in the fourth sections. The step of creating the first cutouts can in particular comprise a process by means of which the exit windows are created or etched free in the form of laser facets.

[0066] In a further step, as shown in Figure 1B, a carrier substrate 11 is provided and arranged on the semiconductor layer stack 2. The carrier substrate 11 has electrical vias 12 which extend from a second upper side 8b to an opposite second lower side 9b. In addition, the carrier substrate 11 has second recesses 15b which extend from the second lower side 9b in the direction of the second upper side 8b and which each expose a second section 13b of a second front side 7b of the carrier substrate 11 of laser devices formed later, as well as an eighth section 13h of a second rear side 16b of the carrier substrate 11 of laser devices formed later.The carrier substrate 11 is arranged on the semiconductor layer stack 2 in such a way that the first upper side 8a is arranged next to the second lower side 9b in contact, that the electrical vias 12 are electrically connected to the remaining regions of the second layer 5, and that the first and second recesses 15a, 15b are each substantially congruent with one another. This results in cavities between the carrier substrate 11 and the semiconductor layer stack 2, which cavities are each formed by a first and a second recess 15a, 15b.

[0067] Optionally, the carrier substrate 11 can have on its second upper side 8b separation markings 19 in the form of trenches, which facilitate a later separation of several laser devices from the wafer structure.

[0068] In a further step, as shown in Figure 1C, the semiconductor layer stack 2 is thinned from a side opposite the carrier substrate 11, so that a first underside 9a of the semiconductor layer stack 2, opposite the first top side 8a, is exposed. The thinning has the effect that unnecessary material of the first layer can be removed in order to improve heat dissipation of the laser devices formed later through the first layer. After the thinning, electrical contact layers 14 are also applied to the exposed first underside 9a, which are in electrical connection with the first layer and which are designed to be arranged at a later time on a contact element, for example a contact element on a target substrate for the laser devices.

[0069] In a subsequent step, as shown in Figure 1D, individual laser devices 1 are singulated from the wafer structure. In particular, the singulation can result in laser devices 1 as shown in the right-hand part of Figure 1D. The singulation step can be carried out in particular along the separation markings 19 and can comprise severing the carrier substrate 11 and the semiconductor layer stack 2 in the region of the first and second recesses 15a, 15b.

[0070] The laser devices 1 each comprise a part of the semiconductor layer stack 2, each having at least one structure designed to constrict current in the active zone 3 to generate laser radiation L. In particular, each laser device 1 has at least one laser channel extending along the active zone between an exit window 10 and a mirror on the opposite first rear side 16a, in particular in the sixth section 13f of the first rear side 16a. Laser radiation L generated in the active zone can be emitted via the exit window 10.

[0071] Due to the creation of the first recesses 15a and the subsequent singulation, the semiconductor layer stack 2 of the laser devices 1 each has a first front side 7a, which is composed of a third and a fourth section 13c, 13d, wherein the fourth section 13d is set back relative to the third section 13c. Likewise, the semiconductor layer stack 2 of the laser devices 1 each has a first rear side 16a, which is composed of a fifth and a sixth section 13e, 13f, wherein the sixth section 13f is set back relative to the fifth section 13e.

[0072] Due to the creation of the second recesses 15b and the subsequent singulation, the carrier substrate 11 of each laser device 1 is also designed such that the carrier substrate 11 of the laser devices 1 in each case has a second front side 7b, which is composed of a first and a second section 13a, 13b, wherein the second section 13b is set back from the first section 13a. Likewise, the carrier substrate of the laser devices 1 in each case has a second rear side 16b, which is composed of a seventh and an eighth section 13g, 13h, wherein the eighth section 13h is set back from the seventh section 13g. Each laser channel is in electrical connection with at least one electrical via 12 and at least one electrical contact layer 14 in order to be able to operate the laser channel in the desired manner.

[0073] The fact that the fourth section 13d is set back compared to the third section 13c is due in particular to the fact that singulating the laser devices 1 in the immediate vicinity of the exit windows 10 could damage the exit windows 10, so that the singulating step takes place at a distance from the fourth section 13d. In order to prevent beam clipping of a laser radiation L emitted from the set-back exit windows 10 through the carrier substrate 11, the second recesses 15b were introduced in the carrier substrate 11, so that a set-back section or a step is also produced for these in the region of the second front side 7b. The step formed in the two rear sides 16a, 16b, in particular in the semiconductor layer stack 2, can be provided for similar reasons.In particular, a reflective surface formed at the exit window 10 and in the sixth section is intended to be protected by the step during the separation of the laser devices 1. Furthermore, the present structure can be formed by the recesses on both the front and back sides due to the manufacturing and separation.

[0074] Figures 2A to 2C each show a plan view of a first underside 9a of a laser device 1 according to the proposed principle. In particular, the figures are intended to show that a laser device 1 can have a plurality of laser channels arranged next to one another, each with a respective exit window. The laser channels can be controlled by means of a common electrical contact layer 14 (Fig. 2C) or can be controlled separately by means of a plurality of electrical contact layers 14 arranged on the first underside 9a (Fig. 2B).

[0075] Figure 3 shows a sectional view of a laser device 1 according to the proposed principle, which is mounted on a target substrate 17. The laser device 1, in particular the electrical via 12, is also electrically connected to its second upper side 8b via a wire contact 18.

[0076] The laser device 1 is mounted on the target substrate 17 with the thinned semiconductor layer stack 2 facing downward. This enables good heat dissipation of the laser device 1 through the first layer 4. In particular, the semiconductor layer stack 2 is thinned to a thickness t1 of at most 50 pm, in particular at most 30 pm, or at most 15 pm, while the carrier substrate 11 can have a thickness t2 of, for example, 80 pm to 200 pm for stabilization during the manufacture of the laser device.

[0077] Figures 4A to 4D show, as also shown in Figures 1A to 1D, steps of a further method for producing a laser device according to the proposed principle. In this case, the only essential difference is the step shown in Figure 4C, namely in that the thinning of the semiconductor layer stack 2 takes place to a depth until the first recesses 15a are reached. Accordingly, the cavities between the semiconductor layer stack 2 and the carrier substrate 11 are opened already at the time of thinning and not only at the time of singulation. This has the consequence that the first front sides 7a, at least in the region of the exit windows 10, do not have the step shown in Figure 1C.

[0078] Such thinning allows the semiconductor layer stack 2 to be made even thinner to provide even better heat dissipation of the laser device 1. A laser device as shown in Figure 4C is shown in a sectional view in Figure 5, which is mounted on a target substrate 17.

[0079] Figures 6A to 6E show two plan views of only the semiconductor stack 2 during steps of a method for producing a laser device 1 according to the proposed principle as well as detailed views and sectional views of the semiconductor layer stack 2 of a resulting laser device 1.

[0080] In particular, it is shown which shape the first cutouts 15a can have and how they can be distributed in the semiconductor layer stack 2. The shown shape in the form of pockets or arrangement in the form of a matrix arrangement is, however, to be understood as an example and can be varied. For example, differently shaped pockets in the form of circles, ovals, hexagons, octagons, etc. would also be conceivable. In particular, it can be seen that the structure 6 for current constriction is interrupted by the pockets and that exit windows 10 or opposite reflective end surfaces are exposed through the pockets. The pockets can be designed with a desired width bl and a desired length 11 depending on requirements.

[0081] Figure 6A also shows that a later lighting device 1 can only comprise one structure 6 for current constriction and accordingly only has one laser channel, or that a later lighting device 1 can comprise a plurality of structures 6 for current constriction and accordingly has a plurality of laser channels. The pockets can in particular be designed such that they do not extend over the entire width of the first upper side 8a of a later laser device, but only over a central region. Viewed from above, this can result in an H-shaped first upper side 8a, as is also shown in the detailed view in Figure 6C. The length 11 of the pockets can in particular determine the depth, how far the fourth section 13d is set back compared to a later produced third section 13c of the first front side 7a.

[0082] Figure 6B shows the dividing lines 20 along which the laser devices 1 are separated, resulting in the third sections 13c of the first front sides 7a and the fifth sections 13e of the first rear sides 16a. Due to the matrix arrangement of the pockets, dividing lines 20 are formed in two mutually perpendicular directions x, y, so that a plurality of laser devices arranged in a matrix

[0083] 1 can be obtained .

[0084] Such a resulting laser device or its semiconductor layer stack 2 is shown in a plan view of the first top side 8a in Figure 6C, and in Figures 6D and 6E, sectional views along the section lines AA and BB are shown. In particular, Figures 6D and 6E show that the stepped configuration of the first front side 7a is limited to the region of the first recess 15a.

[0085] Figures 7A to 7G show corresponding plan views of only the carrier substrate 2 during a step of the method for producing a laser device 1 according to the proposed principle as well as detailed views or sectional views of the carrier substrate 11 of a resulting laser device 1.

[0086] In particular, it is shown which shape the second recesses 15b can have and how they can be distributed in the carrier substrate 11. The shown shape in the form of pockets or arrangement in the form of a matrix arrangement is, however, to be understood as an example and can be varied. For example, differently shaped pockets in the form of circles, ovals, hexagons, octagons, etc. would also be conceivable. The pockets can be designed with a desired width bl and a desired length 11 depending on requirements.

[0087] Figure 7A also shows that the electrical vias 12 can be arranged in different positions and, for example, extend either centrally through the carrier substrate 11 of a laser device 1, or in an edge region of a plurality of laser devices 1, so that only a partial region of the via 12 serves as a later via of the laser device 12 per laser device. In the case shown, the pockets are rectangular and, in particular, are designed such that they do not extend over the entire width of the second underside 9b of a later laser device, but only over a central region. Viewed from above, this can result in an H-shaped second underside 9b, as is also shown in the detailed view in Figures 7B and 7E.The length 11 of the pockets can in particular determine the depth by which the second section 13b is set back from a later produced first section 13a of the second front side 7b.

[0088] The figure also shows the dividing lines 20 along which the laser devices 1 are separated, resulting in the first sections 13a of the second front sides 7b and the seventh sections 13g of the second rear sides 16b. Due to the matrix arrangement of the pockets, dividing lines 20 are formed in two mutually perpendicular directions x, y, so that a plurality of laser devices 1 arranged in a matrix can be obtained.

[0089] Such a resulting laser device 1 or its carrier substrate 11 is shown in a plan view of the second underside 9b in Figures 7B and 7E, and in Figures 7C and 7D or 7F and 7G, sectional views along the section lines AA and BB. In particular, Figures 7C and 7D or 7F and 7G show that the stepped configuration of the second front side 7b is limited to the region of the second recess 15b. In addition, Figures 7C and 7D or 7F and 7G show possible arrangements and configurations of the electrical via 12 in section. The via 12 shown in Figures 7B and 7C can, for example, be designed as a TSV, while the via 12 shown in Figures 7E and 7G can be formed by a coated through-opening.

[0090] Figures 8A to 8D and Figures 9A to 9E show an alternative to the steps or views shown in Figures 6A to 6E and Figures 7A to 7G. In particular, the method and the resulting laser devices 1 differ in that the first and second recesses 15a, 15b are not formed by pockets, but by trenches, resulting in a stepped front side across the entire width of the laser device 1 for both the semiconductor layer stack 2 and the carrier substrate 11 of a laser device. LIST OF REFERENCE SYMBOLS

[0091] 1 laser device

[0092] 2 semiconductor layer stacks

[0093] 3 active zones

[0094] 4 first layer

[0095] 5 second layer

[0096] 6 Structure for current constriction

[0097] 7a , 7b front

[0098] 8a , 8b top

[0099] 9a , 9b bottom

[0100] 10 exit windows

[0101] 11 Carrier substrate

[0102] 12 through-hole plating

[0103] 13a, ..., 13h section

[0104] 14 electrical contact layer

[0105] 15a, 15b recess

[0106] 16a, 16b back

[0107] 17 Target substrate

[0108] 18 wire contact

[0109] 19 Separation mark

[0110] 20 dividing line

[0111] L Laser radiation bl , b2 width

[0112] 11 , 12 Length tl , t2 Thickness x, y Direction

Claims

PATENT CLAIMS 1. Optoelectronic laser device (1) comprising: a semiconductor layer stack (2) with an active zone (3) which is arranged between a first layer (4) a first conductivity type and a second layer (5) of a second conductivity type, at least one structure (6) which is designed to constrict the current in the active zone (3) to generate laser radiation (L), and a first front side (7a) which extends from a first top side (8a) in the direction of a first bottom side (9a) opposite the first top side (8a) and has an exit window (10) for the laser radiation (L) generated in the active zone (3); a carrier substrate (11) with an electrical via (12) which extends from a second top side (8b) to an opposite second bottom side (9b), and a second front side (7b) which extends from the second bottom side (9b) in the direction of the second top side (8b), the second front side (7b) having a first section (13a) adjoining the second top side (8b) and a second section (13b) set back from the first section (13a);and an electrical contact layer (14) arranged on the first underside (9a) and designed to be arranged on a contact element and which is in electrical connection with the first layer (4); wherein the first upper side (8a) and the second underside (9b) are arranged touching one another; and wherein the electrical via (12) is in electrical connection with the second layer (5).

2. Optoelectronic laser device according to claim 1, wherein the first front side (7a) has a third section (13c) adjoining the first underside (9a) and a the third section (13c) set back to the fourth section (13d).

3. Optoelectronic laser device according to claim 1 or 2, wherein the second section (13b) and the first front side (7a), in particular the fourth section (13d) of the first front side (7a), lie substantially in the same plane.

4. Optoelectronic laser device according to claim 2 or 3, wherein the first portion (13a) and the third portion (13c) lie substantially in the same plane.

5. Optoelectronic laser device according to one of the preceding claims, wherein the active zone (3) is arranged between two waveguide layers.

6. Optoelectronic laser device according to one of the preceding claims, wherein the fourth section (13d) is formed by a first recess (15a) in the semiconductor layer stack (2), which extends from the first upper side (8a) in the direction of the first lower side (9a); and / or wherein the second section (13b) is formed by a second recess (15b) in the carrier substrate (11), which extends from the second lower side (9b) in the direction of the second upper side (8b).

7. Optoelectronic laser device according to the preceding claim, wherein the first recess (15a) extends over the entire width (b1) of the first upper side (8a) when viewed in plan view of the first upper side (8a); and / or wherein the second recess (15b) extends over the entire width (b2) of the second lower side (9b) when viewed in plan view of the second lower side (9b).

8. Optoelectronic laser device according to one of claims 6 to 7, wherein the first recess (15a) is formed by a pocket in the semiconductor layer stack (2) which, as seen in plan view of the first upper side (8a), does not extend over the entire width (bl) of the first upper side (8a), in particular over at most 200 pm of the width (bl) of the first upper side (8a); and / or wherein the second recess (15b) is formed by a pocket in the carrier substrate (11) which, as seen in plan view of the second lower side (9b), does not extend over the entire width (b2) of the second lower side (9b), in particular over at most 200 pm of the width (b2) of the second lower side (9b).

9. Optoelectronic laser device according to one of the preceding claims, wherein the semiconductor layer stack (2) has a thickness of at most 50 pm, in particular at most 30 pm, or at most 15 pm.

10. Optoelectronic laser device according to one of the preceding claims, wherein the active zone (3) is arranged at a distance closer to the first upper side (8a) than to the first lower side (9a).

11. Optoelectronic laser device according to one of the preceding claims, wherein the fourth section (13d) is set back from the third section (13c) by at most 100 pm, and in particular by at least 10 pm; and / or wherein the second section (13b) is set back from the first section (13a) by at most 100 pm, and in particular by at least 10 pm.

12. Optoelectronic laser device according to one of the preceding claims, wherein the semiconductor layer stack (2) further comprises a first rear side (16a) opposite the first front side (7a), which extends from the first upper side (8a) in the direction of the first lower side (9a); and wherein optionally the first rear side (16a) has a fifth section (13e) adjoining the first lower side (9a) and a sixth section (13f) set back from the fifth section (13e).

13. Optoelectronic laser device according to one of the preceding claims, wherein the carrier substrate (11) further comprises a second rear side (16b) opposite the second front side (7b) and extending from the second upper side (8b) in the direction of the second lower side (9b); and wherein the second rear side (16b) comprises a seventh section (13g) adjoining the second upper side (8b) and an eighth section (13h) set back from the seventh section (13g).

14. Method for producing a laser device (1), in particular Laser device according to one of the preceding claims, comprising the steps: Providing a semiconductor layer stack (2) with an active zone (3) which is arranged between a first layer (4) a first conductivity type and a second layer (5) of a second conductivity type, and at least one structure (6) which is designed to constrict current in the active zone (3) for generating laser radiation (L); Creating at least one first recess (15a) in the semiconductor layer stack (2) such that a fourth section (13d) of a first front side (7a) of the semiconductor layer stack (2) is exposed, which section extends from a first top side (8a) of the semiconductor layer stack (2) through the second layer (5), the active zone (3) and into the first layer (4), and which exposes an exit window (10) for the laser radiation (L) generated in the active zone (3); Providing a carrier substrate (11) with an electrical through-connection (12) extending from a second upper side (8b) to an opposite second lower side (9b), and at least one second recess (15b) extending from the second lower side (9b) toward the second upper side (8b) and exposing a second portion (13b) of a second front side (7b); and Applying the first upper side (8a) to the second lower side (9b) in such a way that the first upper side (8a) and the second lower side (9b) are arranged touching one another, the electrical via (12) is in electrical connection with the second layer (5), and the first and second recesses (15a, 15b) are substantially opposite one another; Thinning the semiconductor layer stack (2) such that a first bottom side (9a) of the semiconductor layer stack (2) opposite the first top side (8a) is exposed; and Applying an electrical contact layer (14) on the first underside (9a), which is in electrical connection with the first layer (4) and which is designed to be arranged on a contact element.

15. The method according to claim 14, wherein the step of thinning the semiconductor layer stack (2) is carried out such that the at least one first recess (15a) is opened from a side opposite the first top side (8a); and / or that the semiconductor layer stack (2) has a thickness of at most 50 pm, in particular at most 30 pm, or at most 15 pm.

16. The method according to claim 14 or 15, further comprising severing at least the carrier substrate (11) in the region of the at least one second recess (15b), wherein the severing exposes a first portion (13a) of the second front side (7b) which extends from the second top side (8b) in the direction of the second bottom side (9b), and wherein the second section (13b) is set back from the first section (13a).

17. The method according to claim 16, wherein the step of severing comprises severing the semiconductor layer stack (2) in the region of the at least one first recess (15a), wherein the severing of the semiconductor layer stack (2) exposes a third section (13c) of the first front side (7a), which extends from the first underside (9a) in the direction of the first top side (8a), and wherein the fourth section (13d) is set back from the third section (13c).

18. The method according to any one of claims 14 to 17, wherein the step of applying the first upper side (8a) to the second lower side (9b) is carried out in such a way that the at least one first recess (15a) and the at least one second recess (15b) are substantially congruent with one another, in particular in such a way that the second section (13b) and the fourth section (13d) are substantially in the same plane.

19. The method according to one of claims 14 to 18, wherein the at least one first recess (15a) extends over the entire width (b1) of the first upper side (8a) when viewed in plan view of the first upper side (8a), and is in particular designed in the form of a trench; and / or wherein the at least one second recess (15b) extends over the entire width (b2) of the second lower side (9b) when viewed in plan view of the second lower side (9b), and is in particular designed in the form of a trench.

20. The method according to any one of claims 14 to 19, wherein the at least one first recess (15b) is formed by a pocket in the semiconductor layer stack (2) which, viewed in plan view onto the first top side (8a), does not extend beyond the entire width (bl) of the first upper side (8a), in particular over at most 200 pm of the width (bl) of the first upper side (8a); and / or wherein the at least one second recess (15b) is formed by a pocket in the carrier substrate (11) which, when viewed in plan view onto the second lower side (9b), does not extend over the entire width (b2) of the second lower side (9b), in particular over at most 200 pm of the width (b2) of the second lower side (9b).

21. The method according to any one of claims 14 to 20, wherein the step of providing a semiconductor layer stack (2) comprises providing the semiconductor layer stack (2) with a plurality of structures (6) which are designed for current constriction in the active zone (3) for generating laser radiation (L); wherein the method comprises generating a plurality of first recesses (15a) in the semiconductor layer stack (2) such that a plurality of fourth sections (13d) of first front sides (7a) of the semiconductor layer stack (2) are exposed, each extending from a first top side (8a) of the semiconductor layer stack (2) through the second layer (5), the active zone (3) and into the first layer (4), and each exposing at least one exit window (10) for the laser radiation (L) generated in the active zone (3);and wherein the step of providing a carrier substrate (11) comprises providing the carrier substrate (11) with a plurality of second recesses (15b) extending from the second bottom side (9b) towards the second top side (8b) and exposing a plurality of second portions (13b) of second front sides (7b), and wherein the carrier substrate (11) has a plurality of electrical vias (12) extending from the second top side (8b) to the second bottom side (9b); 22. Method according to claim 21, wherein the step of severing separates a plurality of laser devices (1), each comprising at least one of the plurality of structures (6) and one of the plurality of exit windows (10), and each comprising at least one electrical via (12) which is in electrical connection to a portion of the second layer (5).

Images