Light-Emitting Device and Method for Manufacturing a Light-Emitting Device

Abstract

A light-emitting device and a method for manufacturing a light-emitting device are disclosed. In an embodiment, a light-emitting device includes at least one light-emitting semiconductor body with an active layer configured to generate light and a housing comprising a carrier and a cover plate which is transparent to the light. The carrier and the cover plate are connected to each other by a surrounding metal frame and, together with the metal frame, form a hermetically sealed interior space, wherein the at least one light-emitting semiconductor body is arranged inside the interior space, and wherein the cover plate is a growth substrate on which the at least one light-emitting semiconductor body is grown.

Claims

1. Light-emitting device, comprising: at least one light-emitting semiconductor body with an active layer configured to generate light; a housing comprising a carrier and a cover plate which is transparent to the light, wherein the carrier and the cover plate are connected to each other by a surrounding metal frame and, together with the metal frame, form a hermetically sealed interior space, wherein the at least one light-emitting semiconductor body is arranged inside the interior space, and wherein the cover plate is a growth substrate on which the at least one light-emitting semiconductor body is grown.

2. The device according to claim 1, wherein the cover plate comprises sapphire.

3. The device according to claim 1, wherein the cover plate has a surface structure on a surface facing the at least one light-emitting semiconductor body.

4. The device according to claim 1, wherein the metal frame is directly adjacent to the cover plate.

5. The device according to claim 1, wherein the metal frame is soldered to the carrier.

6. The device according to claim 1, wherein the carrier has at least two through-connections through which the at least one light-emitting semiconductor body is electrically contactable from an outside.

7. The device according to claim 6, wherein the at least one light-emitting semiconductor body has at least two electrical contacts on a side remote from the cover plate, and each of the at least two electrical contacts is electrically conductively connected to one of the at least two through-connections, respectively.

8. The device according to claim 1, wherein the at least one light-emitting semiconductor body is a flip chip.

9. The device according to claim 1, wherein the at least one light-emitting semiconductor body is configured to emit light in a UV-C wavelength range during operation.

10. The device according to claim 1, wherein at least two light-emitting semiconductor bodies are arranged in the interior space on the cover plate.

11. The device according to claim 1, wherein the light-emitting device is free of organic materials.

12. A method for manufacturing a light-emitting device, the method comprising: growing a semiconductor layer sequence in a large-area and in a contiguous fashion on a growth substrate; structuring the semiconductor layer sequence into separate semiconductor bodies by removing a semiconductor material on the growth substrate; applying metal frames around the semiconductor bodies, wherein each of the metal frames is applied around at least one of the semiconductor bodies, respectively; placing a carrier plate over the growth substrate on the metal frames; and dividing the carrier plate and the growth substrate between the metal frames so as to form a plurality of light-emitting devices.

13. The method according to claim 12, further comprising: completely removing the semiconductor material of the semiconductor layer sequence between the semiconductor bodies from the growth substrate; and directly applying the metal frames to the growth substrate.

14. The method according to claim 12, wherein applying the metal frames around the semiconductor bodies comprises, for each metal frame, applying a frame-shaped basic metallization and applying a metallic reinforcing layer to the basic metallization by an electroplating method.

15. The method according to claim 12, wherein the carrier plate is soldered to the metal frames.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Further advantages, advantageous embodiments and further developments are revealed by the embodiments described below in connection with the figures, in which:

[0035] FIGS. 1A and 1B show a light-emitting device and a method for producing a light-emitting device according to an embodiment,

[0036] FIG. 2 shows a method for manufacturing a light-emitting device according to another embodiment,

[0037] FIGS. 3A to 11 show method steps of the method shown in FIG. 2 for manufacturing a light-emitting device, and

[0038] FIGS. 12A and 12B show a method step of a method for manufacturing a light-emitting device according to another embodiment.

[0039] In the embodiments and figures, identical, similar or identically acting elements are provided in each case with the same reference numerals. The elements illustrated and their size ratios to one another should not be regarded as being to scale, but rather individual elements, such as, for example, layers, components, devices and regions, may have been made exaggeratedly large to illustrate them better and/or to aid comprehension.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0040] FIGS. 1A and 1B show an embodiment of a light-emitting device 100 and a method for manufacturing the light-emitting device 100.

[0041] The light-emitting device 100 has a housing 1, in which a light-emitting semiconductor body 2 is arranged, which has an active layer for generating light.

[0042] The housing 1 comprises a carrier 3 and a cover plate 4, which are connected to each other by a surrounding metal frame 5 and which form a hermetically sealed interior space 6 with the metal frame 5. In particular, the housing 1 can essentially be formed by the carrier 3, the cover plate 4 and the surrounding metal frame 5.

[0043] The cover plate 4 is transparent to the light generated by the light-emitting semiconductor body 2 during operation, so that the light-emitting device 100 can radiate light to the outside through the cover plate 4 during operation. The light-emitting semiconductor body 2 is arranged in particular on the cover plate 4, which is a growth substrate on which the light-emitting semiconductor body 2 has been grown.

[0044] For electrical contacting of the semiconductor body 2, the semiconductor body 2 has electrical contacts 21 in the form of electrode layers which are arranged on the side of the semiconductor body 2 facing away from the cover plate 4, so that the semiconductor body 2 preferably forms a flip chip. The carrier 3 has through-connections 32 and electrical connection layers 33 on the side of the carrier 3 facing the semiconductor body 2 as well as electrical connection layers 34 on the outer side of the carrier 3 facing away from the semiconductor body 2, the connection layers 33, 34 being connected to one another by the through-connections 32. The electrical contacts 21 of the light-emitting semiconductor body 2 are connected to the connection layers 33 arranged in the interior space 6, so that the light-emitting device 100 can be operated by an electrical connection of the light-emitting device 100 by means of the connection layers 34. The connection layers 34 can be particularly suitable for surface mounting of the light-emitting device 100.

[0045] As shown in FIG. 1B, a semiconductor layer sequence can be grown in a first method step 101 on a growth substrate in order to produce the light-emitting device 100. By removing semiconductor material from the growth substrate, the semiconductor layer sequence can be structured into separate semiconductor bodies in a further method step 102. In a further method step 103, a metal frame is applied to the growth substrate around at least one of the semiconductor bodies formed in this way. Then, in a further method step 104, a carrier plate is applied to the metal frame on the growth substrate. In a further method step 105, the carrier plate and the growth substrate are divided between the metal frames, which laterally enclose the semiconductor bodies, to form a plurality of light-emitting devices as the one shown in FIG. 1A.

[0046] Further and alternative features of the light-emitting device and the method for manufacturing the light-emitting device are described in connection with the following figures.

[0047] In particular, FIG. 2 shows a further example of a method for manufacturing a light-emitting device, with the method steps 201 to 210 indicated in FIG. 2 being explained in greater detail in FIGS. 3A to 11.

[0048] In the first method step 201 shown in FIG. 2, a growth substrate 40 is provided as shown in FIG. 3A. In particular, a growth substrate 40 is provided in the form of a sapphire growth substrate wafer having a surface 41 with a surface structure 42 in the form of regular elevations and depressions as shown in a detailed view in FIG. 3B. The growth substrate 40 is thus formed in particular by a structured sapphire substrate. As described in the general part above, the surface structure 42 can increase the outcoupling efficiency of the finished light-emitting device compared to a corresponding device with a flat substrate.

[0049] As shown in FIG. 4, sapphire has a high transmission for wavelengths up to the UV-C wavelength range. Accordingly, in connection with the following figures, a method for the production of a light-emitting device is described which can radiate light, for example, in the UV-C wavelength range. Alternatively, other wavelength ranges are also possible, which can be determined by a suitable selection of the semiconductor material used.

[0050] In the method step 202 shown in FIG. 2, on the growth substrate 40 a semiconductor layer sequence 10 is then grown on the surface 41 with the surface structure 42 in a large-area and contiguous manner, as shown in FIG. 5. As an example, the semiconductor layer sequence 10 is indicated having a buffer layer 11 and an active layer 12, wherein the growth of the active layer 12 on the growth substrate 40 can be facilitated by the buffer layer 11. The semiconductor layer sequence 10, which in the shown embodiment is based on an InAlGaN compound semiconductor material system, may also include other semiconductor layers as described in the general part above, which are necessary to form a light-emitting semiconductor body. Depending on the growth sequence, the semiconductor layer sequence 10 can end with an n-doped layer or a p-doped layer on the side facing away from the growth substrate 40.

[0051] In method step 203 shown in FIG. 2, as illustrated in FIGS. 6A and 6B, the semiconductor layer sequence 10 is then structured into separate semiconductor bodies 2 by removing semiconductor material from the growth substrate 40. FIG. 6A shows a sectional view corresponding to the views in FIGS. 3A, 3B and 5, while FIG. 6B shows a top view onto the growth surface 41. By way of example, only eight of the semiconductor bodies 2 produced in the wafer compound on the growth substrate 40 are shown. Here and in the following, the dotted lines mark later-used separation areas along which the compound is divided into individual devices.

[0052] The removal of the semiconductor material between the resulting semiconductor bodies 2 can in particular be carried out by an etching method in which the surface 41 of the growth substrate 40 is removed in frame-shaped areas laterally surrounding the semiconductor bodies, so that these areas are free of the semiconductor material.

[0053] Each of the semiconductor bodies 2 is provided with electrical contacts 21 in the form of electrode layers on the side facing away from the growth substrate 40, which, as described above, are intended and designed for the electrical contacting of the semiconductor bodies 2. In addition, other method steps as known from chip manufacture can be carried out, such as mesa etching and/or the application of passivation and/or mirror layers.

[0054] In the further method step 204 shown in FIG. 2, a frame-shaped basic metallization 51 is applied laterally around the semiconductor bodies 2, as illustrated in FIGS. 7A and 7B again in a sectional view and a top view. In the example shown, a frame is formed around each of the semiconductor bodies 2 by the basic metallization 51. The basic metallization 51 fulfils the functions of an adhesion promoter to the growth substrate 40, of a diffusion barrier and of providing a seed layer for the electroplating step described in the following. The basic metallization 51 can have one or preferably several layers. For example, the basic metallization may include or consist of a stack of layers of Ti, Ni, Pt, Pd and/or Au. Particularly preferably, the basic metallization 51 of the growth substrate may comprise or be, for example, a Ti/Pt/Au, a Ti/Pd/Au, a Ti/Ni/Au or a Ti/Ni/Cu layer stack, especially with a thickness of several 100 nm.

[0055] In the further method step 205 shown in FIG. 2, as shown correspondingly in FIGS. 8A to 8C, a metallic reinforcing layer 52 is applied to the frame formed by the basic metallization 51 by means of an electroplating process, whereby, as shown in detail in FIG. 8C in an enlarged section, a metal frame 5 surrounding the semiconductor bodies 2 is formed. The galvanic reinforcement is carried out to a height which corresponds approximately to the height of the semiconductor bodies including the electrical contacts 21, so that the electrical contacts 21 of the semiconductor bodies 2 and the metal frames 5 end at the same height when viewed from the growth substrate 40. The semiconductor bodies 2 can usually have a thickness of a few micrometers, especially in the range from 5 m to 7 m, so that the metal frame 5 can have a corresponding thickness. The reinforcing layer 52 can, for example, be manufactured by Cu-, Ni- or Au-based electroplating.

[0056] In step 206 shown in FIG. 2, a support plate 30 is provided as illustrated in FIG. 9A. The carrier plate 30 can in particular be embodied as a ceramic substrate with high thermal conductivity. Furthermore, it can be particularly advantageous if the carrier plate 30 has a thermal expansion coefficient that is as close as possible to that of the growth substrate 40, i.e., as close as possible to the thermal expansion coefficient of sapphire in the shown embodiment. For example, Al.sub.2O.sub.3, AlN or SiC can be suitable ceramic materials for this purpose.

[0057] The carrier plate 30 is provided with openings 31, which extend through the carrier plate 30. In the further method step 207 shown in FIG. 2, metallic material, such as copper, is filled into the openings 31 to form through-connections 32, as illustrated in FIG. 9B.

[0058] Further method step 208 of FIG. 2 shows, as illustrated in FIG. 9C, that electrical connection layers 33, 34 are applied to the surfaces of the carrier plate 30, which are connected to each other in pairs by the through-connections 32. The connection layers 33 are intended for establishing a connection to the electrical contacts 21 of the semiconductor body 2, while the connection layers 34 form contact structures which are intended in particular for a later SMT assembly, for example, on a metal core board.

[0059] In method step 209 shown in FIG. 2, as illustrated in FIG. 10, the growth substrate 40 carrying the semiconductor bodies 2 and the metal frame 5 is connected at wafer level to the carrier plate 30 having the through-connections 32 and the connection layers 33, 34. This can be done in particular by a soldering process, for example, by means of an AuSn solder, with which the connection layers 33 are connected to the electrical contacts 21. The metal frames 5 can be soldered to the carrier plate 30, which may preferably have corresponding frame-shaped metallizations (not shown). The frame-shaped metallizations on the carrier plate 30 may contain one or more of the materials described above for the basic metallization, e.g., a Ti/Cu/Au layer stack. Subsequently or even before joining, the growth substrate 40 can also be thinned on the side facing away from the semiconductor bodies 2.

[0060] The production of the solder connections between the metal frames 5 and the carrier plate 30 as well as between the electrical contacts 21 and the connection layers 33 can preferably be carried out in the same method step. The soldering method can take place in a gas atmosphere, for example, in an atmosphere with dry air, nitrogen gas or forming gas, in the latter case a mixture of nitrogen or argon with hydrogen. Accordingly, such a gas atmosphere may be present in the interior spaces enclosed by the metal frames 5 in which the light-emitting semiconductor bodies 2 are arranged. Each of the interior spaces can be hermetically sealed by the respective soldered connection.

[0061] In step 210 shown in FIG. 2, as illustrated in Figure ii, the thus formed device compound is divided into individual light-emitting devices 100 along the previously indicated separation lines, by dividing the support plate 30 and the growth substrate 40 so that the resulting portions of the support plate 30 form supports and the resulting portions of the growth substrate 40 form cover plates of the light-emitting devices 100. Subsequently, for example, the light-emitting devices produced in this way can be tested in a further method step.

[0062] FIGS. 12A and 12B show a method step of a method for producing a light-emitting device according to a further embodiment corresponding to the method step described in conjunction with FIGS. 8A to 8C. In comparison to the previous embodiment, a metal frame 5 is not applied individually around each semiconductor body 2. Alternatively, more than two semiconductor bodies 2 can each be enclosed by a metal frame, so that in the resulting light-emitting devices two or more light-emitting semiconductor bodies can be arranged in the interior space of the housing on the cover plate and electrically connected via through-connections in the carrier in the manner described above.

[0063] The features and embodiments described in connection with the figures can be combined with one another according to further embodiments, even if not all combinations are explicitly described. In addition, the embodiments described in connection with the figures may have alternative or additional features according to the description in the general part.

[0064] The invention is not limited by the description based on the embodiments to these embodiments. Rather, the invention includes each new feature and each combination of features, which includes in particular each combination of features in the patent claims, even if this feature or this combination itself is not explicitly explained in the patent claims or embodiments.