Substrate and light-emitting device

Abstract

This substrate includes: a base having a main surface; and a conductive member disposed on the main surface. The conductive member includes: a first section including, layered in order from the bottom, a first conductive layer, a copper layer, and a second conductive layer; and a second section including, layered in order from the bottom, the first conductive layer and the second conductive layer. In a cross section passing through the first section and the second section, a width of the second section obtained by subtracting the thickness of the second conductive layer is 99 μm to 1998.9 μm.

Description

Substrate and light-emitting device

[0001] The present disclosure relates to a substrate and a light emitting device.

[0002] Conventionally, a method for manufacturing a hybrid integrated circuit has been disclosed which includes a step of forming a wiring pattern and then printing copper paste on the wiring pattern excluding the portion of the wiring pattern to be bonded.

[0003] Japanese Patent Publication No. 61-048993

[0004] In recent years, there has been a demand for further improvement in corrosion resistance for substrates and light emitting devices that include conductive members containing copper.

[0005] An object of the present disclosure is to provide a substrate and a light emitting device that can improve the corrosion resistance of a conductive member containing copper.

[0006] According to one aspect of the disclosed technology, a substrate comprises a base having a main surface and a conductive member disposed on the main surface, the conductive member having a first portion having a first conductive layer, a copper layer, and a second conductive layer stacked in that order from the bottom, and a second portion having the first conductive layer and the second conductive layer stacked in that order from the bottom, and in a cross section passing through the first portion and the second portion, the width of the second portion obtained by subtracting the thickness of the second conductive layer is 99 μm or more and 1998.9 μm or less.

[0007] According to one aspect of the disclosed technique, a light emitting device includes a light emitting element, a covering member, and the substrate.

[0008] It is possible to provide a substrate and a light emitting device that can improve the corrosion resistance of conductive members containing copper.

[0009] FIG. 1 is a perspective view schematically showing a light emitting device according to an embodiment. FIG. 2 is a top view schematically showing the light emitting device according to an embodiment. FIG. 3 is a top view schematically showing a substrate constituting the light emitting device according to an embodiment. FIG. 4 is a vertical cross-sectional view taken along line IV-IV in FIG. 2. FIG. 5 is a vertical cross-sectional view taken along line V-V in FIG. 2. FIG. 6 is a vertical cross-sectional view showing a method for manufacturing a substrate included in a light emitting device according to an embodiment. FIG. 7 is a vertical cross-sectional view showing a method for manufacturing a substrate included in a light emitting device according to an embodiment. FIG. 8 is a vertical cross-sectional view showing a method for manufacturing a substrate included in a light emitting device according to an embodiment. FIG. 9 is a vertical cross-sectional view showing a method for manufacturing a substrate included in a light emitting device according to an embodiment. FIG. 10 is a vertical cross-sectional view showing a method for manufacturing a substrate included in a light emitting device according to an embodiment. FIG. 11 is a vertical cross-sectional view showing a method for manufacturing a substrate included in a light emitting device according to an embodiment. FIG. 12A is a vertical cross-sectional view showing a method for manufacturing a substrate included in a light emitting device according to an embodiment. FIG. 12B is a vertical cross-sectional view showing a method for manufacturing a substrate included in a light emitting device according to an embodiment. FIG. 13A is a partial cross-sectional view illustrating a manufacturing process for a light emitting device according to an embodiment. FIG. 13B is a partial cross-sectional view illustrating a manufacturing process for a light emitting device according to an embodiment. FIG. 13C is a partial cross-sectional view illustrating a manufacturing process for a light emitting device according to an embodiment. FIG. 13D is a partial cross-sectional view illustrating a manufacturing process of the light emitting device according to the embodiment.

[0010] Hereinafter, a manufacturing method according to an embodiment of the present invention and a light-emitting device obtained by the manufacturing method (hereinafter, sometimes referred to as a "light-emitting device according to an embodiment") will be described with reference to the drawings. In the following description, terms indicating specific directions or positions (e.g., "upper," "lower," and other terms including these terms) will be used as necessary. However, the use of these terms is intended to facilitate understanding of the invention with reference to the drawings, and the meaning of these terms does not limit the technical scope of the present invention. Furthermore, parts that appear with the same reference numerals in multiple drawings indicate the same or equivalent parts or components.

[0011] Furthermore, the embodiments shown below are intended to exemplify light-emitting devices and the like that embody the technical concepts of the present invention, and are not intended to limit the present invention thereto. Furthermore, unless otherwise specified, the dimensions, materials, shapes, relative arrangements, etc. of the components described below are intended for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, the content described in one embodiment may also be applicable to other embodiments and modified examples. Furthermore, the size and positional relationships of components shown in the drawings may be exaggerated for clarity. Furthermore, to avoid overly complex drawings, schematic diagrams may be used in which some elements are omitted, or end views may be used as cross-sectional views that show only the cut surface.

[0012] <Light-emitting device 1 according to an embodiment> Fig. 1 is a perspective view schematically showing a light-emitting device according to an embodiment. Fig. 2 is a top view schematically showing the light-emitting device according to an embodiment. Fig. 3 is a top view schematically showing a substrate constituting the light-emitting device according to an embodiment. Fig. 4 is a vertical cross-sectional view taken along line IV-IV in Fig. 2. Fig. 5 is a vertical cross-sectional view taken along line V-V in Fig. 2. Note that the vertical cross-section is a cross-section of the light-emitting device 1 cut along a plane perpendicular to the upper surface 20a of the light-emitting element 20.

[0013] 1 to 5, the light emitting device 1 includes a substrate 10, a light emitting element 20, and a covering member 60. The substrate 10 includes a base 11 having a main surface 11A, and a conductive member 12 disposed on the main surface 11A. In this embodiment, the conductive member 12 is a wiring, and the substrate 10 including the conductive member 12 is a wiring substrate. The main surface 11A of the base 11 is referred to as the upper surface 11A of the base 11.

[0014] In this embodiment, the light emitting device 1 has a plurality of light emitting elements 20, and in the light emitting device 1, the plurality of light emitting elements 20 can emit light independently.

[0015] In the light-emitting device 1, a plurality of light-emitting elements 20 are placed on a substrate 10. The light-emitting elements 20 have an upper surface 20a, a plurality of side surfaces 20c continuous with the upper surface 20a, and a lower surface 20b opposite the upper surface 20a. The plurality of side surfaces 20c are continuous with the upper surface 20a and the lower surface 20b. In other words, the plurality of side surfaces 20c each have an outer edge continuous with the outer edge of the upper surface 20a and the outer edge of the lower surface 20b. In the light-emitting element 20, light is emitted from the upper surface 20a, the lower surface 20b, and the side surfaces 20c.

[0016] The light-emitting element 20 has a substantially rectangular upper surface 20a. For example, the light-emitting element 20 has an external shape that is substantially rectangular parallelepiped or substantially cubic. In this case, the upper surface 20a and the lower surface 20b of the light-emitting element 20 are substantially rectangular, and the light-emitting element 20 has four substantially rectangular side surfaces 20c. The shape of the upper surface 20a of the light-emitting element 20 may be a polygon such as a triangle or a hexagon. Furthermore, the external shape of the light-emitting element 20 may be a columnar or frustum with a polygonal upper surface.

[0017] The light-emitting device 1 further includes a light-transmitting member 50. In this embodiment, a plurality of light-transmitting members 50 are disposed on each of the plurality of light-emitting elements 20. The number of light-transmitting members 50 is, for example, the same as the number of light-emitting elements 20. The distance between adjacent light-transmitting members 50 is, for example, 50 μm or less. The light-transmitting member 50 has an upper surface 50 a, a lower surface 50 b opposite the upper surface 50 a, and a side surface 50 c between the upper surface 50 a and the lower surface 50 b. The upper surface 50 a of the light-transmitting member 50 constitutes the upper surface of the light-emitting device 1 as the main light-emitting surface of the light-emitting device 1. The lower surface 50 b of the light-transmitting member 50 is bonded to the upper surface 20 a of the light-emitting element 20. The light-transmitting member 50 and the light-emitting element 20 may be joined via a light-transmitting adhesive made of silicone resin or the like arranged between the lower surface 50b of the light-transmitting member 50 and the upper surface 20a of the light-emitting element 20, or the lower surface 50b of the light-transmitting member 50 may be in contact with the upper surface 20a of the light-emitting element 20. The light-transmitting member 50 is arranged so that the lower surface 50b of the light-transmitting member 50 is approximately parallel to the upper surface 20a of the light-emitting element 20. The shape of the lower surface 50b of the light-transmitting member 50 is preferably the same as or similar to the shape of the upper surface 20a of the light-emitting element 20. For example, if the upper surface 20a of the light-emitting element 20 is rectangular, the lower surface 50b of the light-transmitting member 50 is preferably also rectangular. Note that the number of light-transmitting members 50 included in the light-emitting device 1 may be fewer than the number of light-emitting elements 20. When the light emitting device 1 is provided with a plurality of translucent members whose number is less than the number of light emitting elements 20, for example, at least one of the plurality of translucent members is arranged so as to collectively cover the plurality of light emitting elements 20.

[0018] The lower surface 50b of the light-transmitting member 50 is a flat surface. The upper surface 50a of the light-transmitting member 50 may be a flat surface parallel to the lower surface 50b, or part or all of the upper surface 50a may be a surface that is not parallel to the lower surface 50b. The side surface 50c of the light-transmitting member 50 may be a surface that is perpendicular to at least one of the upper surface 50a and the lower surface 50b, an inclined surface, a curved surface, or the like. The light-transmitting member 50 may have an uneven structure on part or all of its surface.

[0019] The lower surface 50b of the light-transmitting member 50 has an area larger than the upper surface 20a of the light-emitting element 20. In this case, it is preferable that the light-transmitting member 50 is disposed so that the lower surface 50b of the light-transmitting member 50 encloses the light-emitting element 20 when viewed from above. The lower surface 50b of the light-transmitting member 50 may have an area smaller than or the same as the area of ​​the upper surface 20a of the light-emitting element 20.

[0020] The covering member 60 exposes the upper surface 50a of each light-transmitting member 50 and collectively covers the side surface 50c of each light-transmitting member 50 and the side surface 20c of each light-emitting element 20. The covering member 60 may cover at least a portion of the upper surface of the substrate 10. The light-emitting device 1 may further include a protective element placed on the substrate 10 to protect the light-emitting element 20. The protective element is, for example, a Zener diode. When the light-emitting device 1 includes a protective element, the covering member 60 preferably covers the upper surface, lower surface, and side surface of the protective element. Furthermore, the covering member 60 may cover the lower surface 20b of each light-emitting element 20.

[0021] In the light emitting device 1, the covering member 60, together with the base 11 of the substrate 10, constitutes the side surface of the light emitting device 1. In this embodiment, the side surface of the covering member 60 that constitutes the side surface of the light emitting device 1 and the side surface of the base 11 are flush with each other. Furthermore, the upper surface 60a of the covering member 60 that constitutes the upper surface of the light emitting device 1 and the upper surface 50a of the translucent member 50 are flush with each other. Note that the side surface of the covering member 60 and the side surface of the base 11 do not have to be flush with each other, and the upper surface 60a of the covering member 60 and the upper surface 50a of the translucent member 50 do not have to be flush with each other.

[0022] The substrate 10 according to this embodiment includes a base 11 and a conductive member 12 disposed on a main surface 11A (top surface 11A in this embodiment) of the base 11. The base 11 supports the conductive member 12. The substrate 10 is a member on which the light-emitting element 20 is mounted. The conductive member 12 is used to supply power to the light-emitting element 20 from the outside. The substrate 10 may also have wiring on its bottom surface, which is located on the opposite side of the top surface 11A of the base 11.

[0023] The base 11 has, for example, a substantially rectangular parallelepiped or cubic shape. It is preferable to use a material for the base 11 that is less transparent to light emitted from the light-emitting element 20 and external light. Examples of materials for the base 11 include ceramics such as aluminum oxide, aluminum nitride, silicon nitride, and mullite; epoxy resin, silicone resin, modified epoxy resin, urethane resin, phenolic resin, polyimide resin, BT (bismaleimide triazine) resin, and polyphthalamide; semiconductors such as silicon; metals such as copper and aluminum; and graphite, as well as composite materials thereof. Among these, ceramics with excellent heat dissipation properties are preferably used as the material for the base 11. Nitride ceramics are preferred as the material for the base 11. Examples of nitride ceramics include silicon nitride and aluminum nitride. The thickness of the base 11 is, for example, 0.1 mm to 0.5 mm in the case of silicon nitride, and 0.3 mm to 2 mm in the case of aluminum nitride. The upper surface 11A of the base 11 has a first region 91 where the covering member 60 is disposed and a second region 92 exposed from the covering member 60 .

[0024] The conductive member 12 has a first portion 81 having a first conductive layer 31, a copper layer 32, and a second conductive layer 33 stacked in this order from the bottom, and a second portion 82 having the first conductive layer 31 and the second conductive layer 33 stacked in this order from the bottom. In this embodiment, the first layer 41 of the first conductive layer 31 and the second conductive layer 33 each have a higher halogen resistance than the copper layer 32.

[0025] The first conductive layer 31 includes a first layer 41. In the example shown in FIG. 5 , the first conductive layer 31 has a first layer 41 and a seed layer 42 stacked in this order from bottom to top. The first layer 41 contains titanium. In this embodiment, the first layer 41 contains a titanium-tungsten alloy. The first layer 41 is disposed on the substrate 11. The first layer 41 and the substrate 11 are in contact with each other. The thickness of the first layer 41 is, for example, 0.05 μm or more and 0.5 μm or less. The seed layer 42 may be made of, for example, copper. The thickness of the seed layer 42 is, for example, 0.05 μm or more and 0.5 μm or less. The seed layer 42 is disposed only on the first portion 81 and not on the second portion 82. The first layer 41 and the seed layer 42 may include a native oxide film on at least one of their respective surfaces and their respective interfaces. Furthermore, if a natural oxide film is present on the surface and interface of each of the first layer 41 and the seed layer 42, the first layer 41, the seed layer, and the substrate 11 can be considered to be in contact with each other, since the natural oxide film is thin enough to conduct electricity.

[0026] A natural oxide film is easily formed on the surface of titanium. Furthermore, titanium has strong resistance to halogens, making it highly resistant to halogen-containing chlorides such as sodium chloride. In the first layer 41 containing a titanium-tungsten alloy, titanium is in contact with the substrate 11, which is a nitride. Therefore, when the conductive member 12 is heat-treated, titanium nitride is formed at the interface between the first layer 41 and the substrate 11, providing strong adhesion between the titanium and the nitride. Furthermore, the linear expansion coefficient of tungsten is close to that of nitride ceramics. Therefore, large thermal stress is unlikely to occur between tungsten and ceramic, resulting in strong adhesion between the first layer 41 and the substrate 11.

[0027] The copper layer 32 is disposed only in the first portion 81 and not in the second portion 82. The thickness of the copper layer 32 is, for example, 1 μm or more and 90 μm or less. The copper layer 32 may include a natural oxide film on its surface. Copper has high thermal conductivity and is a soft metal. Therefore, by forming the copper layer 32 to a thickness in the range of 1 μm or more and 90 μm or less, preferably 10 μm or more and 30 μm or less, the copper layer 32 has good mountability and connection reliability when flip-chip mounted to the light-emitting element 20 using gold bumps.

[0028] The second conductive layer 33 has, for example, a second layer 71, a palladium layer 72, and a gold layer 73 stacked in this order from the bottom. The second layer 71 contains nickel. The thickness of the second layer 71 is, for example, 1 μm or more and 10 μm or less. The thickness of the palladium layer 72 is, for example, 0.05 μm or more and 0.5 μm or less. The thickness of the gold layer 73 is, for example, 0.05 μm or more and 0.5 μm or less. The thickness of the second conductive layer 33 is, for example, 1.1 μm or more and 11 μm or less. In the second portion 82, the first layer 41 and the second layer 71 contact each other.

[0029] A natural oxide film is likely to form on the surface of nickel. Nickel also has strong resistance to halogens and oxygen. When the copper layer 32 and the gold layer 73 are in contact with each other, an alloy is likely to form between them. The nickel contained in the second layer 71 prevents copper diffusion, so the second layer 71 functions as a diffusion barrier between the copper layer 32 and the gold layer 73. Palladium has strong resistance to sulfur. Palladium also prevents the diffusion of nickel and gold. When the second layer 71 and the gold layer 73 are in contact with each other, for example, when the conductive member 12 is heat-treated, an alloy may form between the nickel and gold, but the palladium layer 72 functions as a diffusion barrier between the second layer 71 and the gold layer 73.

[0030] When wiring is provided on the underside of the base 11, the wiring may include an anode electrode and a cathode electrode electrically connected to an external power supply. Furthermore, when wiring is provided on the underside of the base 11, the substrate 10 may be provided with relay wiring inside or on at least one of the side surfaces of the base 11 for connecting the conductive member 12 to the wiring arranged on the underside of the base 11. Furthermore, the conductive member 12 may include wiring for heat dissipation on the underside of the base 11 in addition to the anode electrode and the cathode electrode electrically connected to the light-emitting element 20. For example, metals such as iron, copper, nickel, aluminum, gold, silver, platinum, titanium, tungsten, and palladium, or alloys containing at least one of these metals, can be used for the wiring on the underside of the base 11.

[0031] The substrate 10 does not need to have wiring on the lower surface of the base 11. In this case, an anode electrode and a cathode electrode electrically connected to an external power supply may be disposed on the upper surface or side surface of the base 11.

[0032] The substrate 10 may have a recess on the top surface, and the light emitting device 1 may have a structure in which the light emitting element 20 is disposed at the bottom of the recess in the substrate 10 .

[0033] Furthermore, the substrate 10 may further include an insulating member that covers the base body 11 and at least the first portion of the conductive member 12 .

[0034] Hereinafter, each element constituting the light emitting device 1 according to the embodiment will be described in detail.

[0035] (Light-Emitting Element 20) The light-emitting element 20 can be suitably a semiconductor light-emitting element such as a light-emitting diode (LED) chip or a semiconductor laser (LD) chip. The shape, size, and the like of the light-emitting element 20 can be selected arbitrarily. The light-emitting element 20 has, for example, multiple electrodes on its lower surface 20b. The light-emitting element 20 is disposed on the substrate 10. The light-emitting element 20 is flip-chip mounted to the substrate 10, for example, with the lower surface 20b with the electrodes facing the substrate 10. The multiple electrodes of the light-emitting element 20 are electrically connected to the conductive member 12. The light-emitting element 20 and the conductive member 12 can be connected using a known conductive bonding member 25, such as eutectic solder, conductive paste, or bumps. The electrodes of the light-emitting element 20 and the conductive member 12 may be directly bonded to each other without the conductive bonding member 25.

[0036] The light-emitting element 20 includes, for example, a semiconductor structure and a support substrate that supports the semiconductor structure. The semiconductor structure includes an n-side semiconductor layer, a p-side semiconductor layer, and an active layer sandwiched between the n-side semiconductor layer and the p-side semiconductor layer. The active layer may have a single quantum well (SQW) structure or a multiple quantum well (MQW) structure including multiple well layers. The semiconductor structure includes multiple semiconductor layers made of nitride semiconductors. The nitride semiconductors include In ｘ Al ｙ Ga １－ｘ－ｙ The term "active layer" includes semiconductors of all compositions in which the composition ratios x and y in the chemical formula N (0≦x, 0≦y, x+y≦1) are varied within their respective ranges. The emission peak wavelength of the active layer can be appropriately selected depending on the purpose. The active layer is configured to be able to emit, for example, visible light or ultraviolet light.

[0037] The semiconductor structure may include multiple light-emitting sections, each including an n-side semiconductor layer, an active layer, and a p-side semiconductor layer. When the semiconductor structure includes multiple light-emitting sections, each light-emitting section may include well layers with different emission peak wavelengths or well layers with the same emission peak wavelength. Note that the same emission peak wavelength also includes cases where the emission peak wavelengths vary by a few nanometers. The combination of emission peak wavelengths of the multiple light-emitting sections can be appropriately selected. For example, when the semiconductor structure includes two light-emitting sections, the combination of light emitted by each light-emitting section may include blue light and blue light, green light and green light, red light and red light, ultraviolet light and ultraviolet light, blue light and green light, blue light and red light, or green light and red light. For example, when the semiconductor structure includes three light-emitting sections, the combination of light emitted by each light-emitting section may include blue light, green light, and red light. Each light-emitting section may include one or more well layers with emission peak wavelengths different from those of the other well layers.

[0038] The light-emitting element 20 shown in FIG. 4 has one semiconductor structure on one support substrate. One semiconductor structure has only one light-emitting layer. Note that the light-emitting element 20 may have multiple semiconductor laminates on one support substrate. Also, one semiconductor structure may have multiple light-emitting layers. The structure of the semiconductor structure having multiple light-emitting layers may be a structure including multiple active layers between one n-side semiconductor layer and one p-side semiconductor layer, or a structure in which a structure including an n-side semiconductor layer, an active layer, and a p-side semiconductor layer in that order is repeated multiple times.

[0039] In the light emitting device 20, a plurality of electrodes are disposed on the semiconductor structure. The electrodes include an n-electrode connected to the n-side semiconductor layer and a p-electrode connected to the p-side semiconductor layer. The p-electrode and the n-electrode may be disposed on different surfaces of the semiconductor laminate, or may be disposed on the same surface. In this case, the plurality of electrodes including the p-electrode and the n-electrode are disposed on the same surface of the semiconductor structure, and the side on which the plurality of electrodes are disposed constitutes the lower surface 20b of the light emitting device 20, and the surface of the support substrate opposite to the surface on which the semiconductor structure is disposed constitutes the upper surface 20a of the light emitting device 20. The support substrate may be made of sapphire or spinel (MgAl ２ O４ Examples of suitable substrates include insulating substrates such as silicon dioxide, silicon dioxide, and nitride-based semiconductor substrates such as gallium nitride. In order to extract light emitted from the active layer through the support substrate, it is preferable to use a light-transmitting material for the support substrate. Note that the light-emitting element 20 does not necessarily have to have a support substrate. For example, the support substrate can be removed after the semiconductor structure is formed on the support substrate.

[0040] (Light-Transmitting Member 50) The light-transmitting member 50 is disposed on the light-emitting element 20 and transmits light emitted from the light-emitting element 20 to release it to the outside. The light-transmitting member 50 may transmit 60% or more of the light from the light-emitting element 20 and light obtained by wavelength conversion of the light from the light-emitting element 20 using a phosphor described below (for example, light having an emission peak wavelength in the wavelength range of 320 nm to 850 nm), and preferably transmits 70% or more of the light. The light-transmitting member 50 may be formed from an inorganic material such as glass, ceramic, or sapphire, or an organic material such as a resin or hybrid resin containing one or more of silicone resin, modified silicone resin, epoxy resin, modified epoxy resin, acrylic resin, phenolic resin, or fluororesin.

[0041] The light-transmitting member 50 may contain a phosphor capable of wavelength conversion of at least a portion of incident light. Examples of light-transmitting members 50 containing a phosphor include a sintered body of a phosphor and the above-mentioned materials containing phosphor powder. The light-transmitting member 50 may also be a molded body of resin, glass, ceramic, or the like, with a light-transmitting layer, such as a resin layer containing a phosphor or a glass layer containing a phosphor, formed on the surface thereof. The light-transmitting member 50 may also contain a filler such as a light-diffusing material depending on the purpose. When a filler, such as a light-diffusing material, is contained, the light-transmitting member 50 may be a resin, glass, ceramic, or other inorganic material containing the filler, or a light-transmitting plate, such as a molded body of resin, glass, ceramic, or the like, with a light-transmitting layer, such as a resin layer containing a filler or a glass layer containing a filler, formed on the surface thereof.

[0042] The phosphor is an yttrium aluminum garnet phosphor (e.g., (Y, Gd) ３ (Al, Ga)５ O １２ :Ce), lutetium aluminum garnet phosphors (e.g., Lu ３ (Al, Ga) ５ O １２ :Ce), terbium aluminum garnet phosphors (e.g., Tb ３ (Al, Ga) ５ O １２ :Ce), CCA-based phosphors (e.g., Ca １０ (P.O. ４ ) ６ Cl ２ :Eu), SAE-based phosphors (e.g., Sr ４ Al １４ O ２５ :Eu), chlorosilicate phosphors (e.g., Ca ８ MgSi ４ O １６ Cl ２ :Eu), silicate-based phosphors (e.g., (Ba, Sr, Ca, Mg) ２ SiO ４ :Eu), β-sialon-based phosphors (e.g., (Si, Al) ３ (O, N) ４ :Eu) or α-sialon-based phosphor (e.g., Ca(Si,Al) １２ (O, N) １６ oxynitride phosphors such as (La,Y) ３ Si ６ N １１ :Ce), BSESN-based phosphors (e.g., (Ba, Sr) ２ Si ５ N ８ :Eu), SLA-based phosphors (e.g., SrLiAl ３ N ４ :Eu), CASN-based phosphors (e.g., CaAlSiN ３ :Eu) or SCASN-based phosphors (e.g., (Sr,Ca)AlSiN ３ nitride-based phosphors such as KSF-based phosphors (e.g., K ２ SiF ６ :Mn), KSAF-based phosphors (e.g., K ２ (Si １－ｘ Al ｘ ) F ６－ｘ:Mn where x satisfies 0<x<1) or MGF-based phosphor (for example, 3.5MgO.0.5MgF ２ GeO ２ Fluoride-based phosphors such as (Cs,FA,MA)(Pb,Sn)(F,Cl,Br,I) and quantum dots having a perovskite structure (e.g., (Cs,FA,MA)(Pb,Sn)(F,Cl,Br,I) ３ Here, FA and MA represent formamidinium and methylammonium, respectively.), II-VI quantum dots (e.g., CdSe), III-V quantum dots (e.g., InP), or quantum dots with a chalcopyrite structure (e.g., (Ag,Cu)(In,Ga)(S,Se) ２ ) etc. can be used.

[0043] As the light diffusing material, any material known in the art can be used, such as titanium dioxide, silicon dioxide, aluminum oxide, barium titanate, etc.

[0044] Furthermore, when the light-transmitting member 50 includes at least one of a phosphor layer and a light-diffusing material layer, and a resin is used as the base material of the phosphor layer and the light-diffusing material layer, examples of the resin include thermosetting resins such as epoxy resin, modified epoxy resin, silicone resin, and modified silicone resin.

[0045] (Coating Member 60) The covering member 60 covers the first portion 81 of the conductive member 12, and the first boundary 83 between the first portion 81 and the second portion 82 is also covered by the covering member 60. The thickness of the covering member 60 is greater than 0 μm and less than 998.9 μm. The light-emitting element 20 is connected to the second conductive layer 33 at the first portion 81 of the conductive member 12 and is covered by the covering member 60. The covering member 60 preferably has light-blocking properties, specifically, preferably has at least one of light reflectivity and light absorption properties. In particular, it preferably contains a material that can favorably reflect light emitted from the light-emitting element 20. For example, it preferably has a reflectivity of 60% or more for light emitted from the light-emitting element 20, and more preferably has a reflectivity of 70% or more, 80% or more, or 90% or more. An example of a material that can favorably absorb light emitted from the light-emitting element 20 is carbon black.

[0046] By covering the side surface 20c of the light emitting element 20 with the covering member 60, light emitted from the side surface 20c of the light emitting element 20 is reflected by the covering member 60. Furthermore, by covering the lower surface 20b of the light emitting element 20 with the covering member 60, light traveling downward from the light emitting element 20 is reflected by the covering member 60. These features make it possible to improve the light extraction efficiency of the light emitting device 1. The covering member 60 may be made up of a single member or multiple members.

[0047] The covering member 60 is preferably made of an insulating material. The covering member 60 is, for example, a member obtained by incorporating particles of a light-reflecting substance into a translucent resin. Examples of resins used for the covering member 60 include resins or hybrid resins containing one or more of silicone resin, modified silicone resin, epoxy resin, modified epoxy resin, urea resin, acrylic resin, phenolic resin, bismaleimide triazine resin, and polyphthalamide resin. Among these, silicone resin is particularly preferred because of its excellent light resistance, heat resistance, electrical insulation, and flexibility. Examples of light-reflecting substances include titanium dioxide, silicon dioxide, aluminum oxide, zirconium dioxide, magnesium oxide, potassium titanate, barium titanate, zinc oxide, silicon nitride, aluminum nitride, boron nitride, calcium carbonate, calcium hydroxide, calcium silicate, and combinations thereof. Among these, titanium dioxide, which has a relatively high refractive index, is preferred from the standpoint of light reflection.

[0048] In the light emitting device 1, the first conductive layer 31, the copper layer 32, and the second conductive layer 33 are stacked in this order from the bottom up in the first portion 81, and the first conductive layer 31 and the second conductive layer 33 are stacked in this order from the bottom up in the second portion 82. Therefore, the copper layer 32 is less likely to be exposed to external corrosive substances, thereby improving the corrosion resistance of the substrate 10 and the light emitting device 1. In particular, the resistance to halogen of each of the first conductive layer 31 and the second conductive layer 33 is higher than the resistance to halogen of the copper layer 32, thereby improving the corrosion resistance to halogen.

[0049] When the first layer 41 contains titanium, a natural oxide film is formed on the surface of the first layer 41. The natural oxide film on the surface of the first layer 41 is formed, for example, when the first layer 41 is exposed to the atmosphere. When the second layer 71 contains nickel, a natural oxide film is also formed on the surface of the second layer 71 during and after the formation of the second layer 71. The natural oxide film on the surface of the second layer 71 is formed, for example, during plating of the second layer 71 or by the diffusion of oxygen contained in the coating member 60 and the substrate 11. Because natural oxide films are formed on the surfaces of the first layer 41 and the second layer 71 in this manner, high adhesion is achieved between the oxide film on the surface of the first layer 41 and the oxide film on the surface of the second layer 71. Furthermore, the contact between the first layer 41 and the second layer 71 in the second portion 82 makes it difficult for corrosive substances to penetrate into the copper layer 32 through the gap between the first layer 41 and the second layer 71.

[0050] When the first layer 41 contains titanium, the base 11 contains nitride ceramic, and the first layer 41 and the base 11 are in contact with each other, when the conductive member 12 is heat-treated, the titanium contained in the first layer 41 and the nitrogen contained in the base 11 produce titanium nitride at the interface between the first layer 41 and the base 11. As a result, high adhesion is obtained between the first layer 41 and the base 11.

[0051] The thickness of the copper layer 32 is preferably 1 μm or more and 90 μm or less, and more preferably 10 μm or more and 30 μm or less. When the thickness of the copper layer 32 is 10 μm or more, even if thermal stress acts on the conductive member 12 when the light emitting element 20 is mounted, the thermal stress can be absorbed by the copper layer 32, making it less likely that the conductive member 12 will peel off. Furthermore, when the thickness of the copper layer 32 is 90 μm or less, the substrate 10 and the light emitting device 1 will not become excessively thick.

[0052] Since the first boundary 83, which is the boundary between the first part 81 and the second part 82, is covered with the covering member 60, the covering member 60 also makes it difficult for corrosive substances to penetrate into the copper layer 32, thereby improving the corrosion resistance of the light-emitting device 1.

[0053] The distance L1 between the first boundary 83 and the second boundary 93, which is the boundary between the first region 91 and the second region 92 on the upper surface 11A of the base 11, is preferably 10 μm or more. This allows a larger portion of the second portion 82 of the conductive member 12 to be covered by the covering member 60, making it more difficult for corrosive substances to penetrate the copper layer 32 and improving the corrosion resistance of the light emitting device 1. The distance L1 is more preferably 20 μm or more, and even more preferably 30 μm or more. The distance L1 is, for example, 1000 μm or less. Note that the distance L1 is the distance in a vertical cross section perpendicular to the side surface of the covering member 60 where the conductive member 12 is exposed.

[0054] Furthermore, in a top view, the distance L2 from the second boundary 93 to the outer edge of the second portion 82 is preferably 100 μm or more. This facilitates wire bonding to the portion of the second portion 82 exposed from the covering member 60. The distance L2 is more preferably 200 μm or more, and even more preferably 300 μm or more. The distance L2 is, for example, 1000 μm or less. The sum of the distances L1 and L2 is 100 μm or more and 2000 μm or less. Therefore, in a cross section passing through the first portion 81 and the second portion 82, the width A2 of the second portion 82 obtained by subtracting the thickness A1 of the second conductive layer 33 is 99 μm or more and 1998.9 μm or less. Note that the width A2 of the second portion 82 obtained by subtracting the thickness A1 of the second conductive layer 33 from the respective preferred values ​​of the distances L1 and L2 is the width A2 of the second portion 82 obtained by subtracting the thickness A1 of the second conductive layer 33. In the present disclosure, a "cross section" refers to a cross section perpendicular to the upper surface 11A of the base 11 and the first boundary 83.

[0055] The light emitting device 1 can be used, for example, in an automobile headlamp. When the light emitting device 1 is used in an automobile headlamp, it may be exposed to rain or fog containing salt or rain or fog containing sulfur. Even in such cases, the copper layer 32 is not easily exposed to these corrosive substances, so the light emitting device 1 can operate stably for a long period of time and achieve excellent reliability.

[0056] <Method of Manufacturing Light-Emitting Device According to Embodiment> A method of manufacturing a light-emitting device according to an embodiment will now be described. First, a method of manufacturing the substrate 10 will be described. Figures 6 to 12A and 12B are vertical cross-sectional views showing a method of manufacturing a substrate included in the light-emitting device according to this embodiment.

[0057] First, as shown in FIG. 6 , a substrate 11 is prepared, and a step of disposing a first conductive layer 31 over the entire upper surface 11A of the substrate 11 is performed. In the step of disposing the first conductive layer 31, a first layer 41 containing a titanium-tungsten alloy is disposed over the entire upper surface 11A of the substrate 11, and a seed layer 42 containing copper is disposed over the entire upper surface of the first layer 41. When the first layer 41 contains a titanium-tungsten alloy, the first layer 41 is preferably disposed by a sputtering method. The seed layer 42 can be disposed by a sputtering method or an electroless plating method. When the first layer 41 and the seed layer 42 are disposed by a sputtering method, the heating temperature is high and the film can be formed with strong energy, resulting in a higher Vickers hardness than when the first layer 41 and the seed layer 42 are disposed by an electroless plating method.

[0058] Next, as shown in FIG. 7 , a step of placing a mask 110 on the seed layer 42 is performed. The mask 110 has openings 111 in areas where the conductive members 12 are to be formed. The mask 110 is, for example, photoresist. If the photoresist is liquid, it is applied by spin coating. If the photoresist is a dry film, it is laminated using a heat roll laminator. In either case, the mask 110 is placed by subsequently forming a photoresist pattern through exposure and development.

[0059] 8, a step of disposing a copper layer 32 on the seed layer 42 inside the opening 111 is performed. The copper layer 32 can be disposed by electrolytic plating or the like. After disposing the copper layer 32, the mask 110 is removed.

[0060] Next, as shown in FIGS. 9 , 10 , and 11 , a process is performed to remove the portions of the first conductive layer 31 exposed from the copper layer 32. The portions of the first conductive layer 31 exposed from the copper layer 32 can be removed by wet etching. This wet etching is sometimes called flash etching. As shown in FIG. 10 , a mask 120 is placed on the copper layer 32. The mask 120 has openings 121 in the areas where the second portions 82 of the conductive member 12 are to be formed, and covers the areas where the first portions 81 are to be formed. The mask 120 is, for example, the same photoresist as described above. Next, as shown in FIG. 11 , the portions of the copper layer 32 and the seed layer 42 exposed from the mask 120 are removed. As a result, the first layer 41 is exposed from the copper layer 32 and the seed layer 42 in the areas where the second portions 82 of the conductive member 12 are to be formed. The portions of the copper layer 32 and the seed layer 42 exposed from the mask 120 can be removed by wet etching. Then, the mask 120 is removed.

[0061] Next, as shown in FIG. 12A , a process of disposing a second conductive layer 33 on the first conductive layer 31 and the copper layer 32 is performed. In the process of disposing the second conductive layer 33, a second layer 71 is disposed on the first conductive layer 31 and the copper layer 32, a palladium layer 72 is disposed on the second layer 71, and a gold layer 73 is disposed on the palladium layer 72. The second layer 71, the palladium layer 72, and the gold layer 73 can be disposed by electroless plating or the like. The second layer 71, the palladium layer 72, and the gold layer 73 are preferably disposed by plating. Since electroless plating can be performed at room temperature, it does not require energy for heating, and the second layer 71, the palladium layer 72, and the gold layer 73 can be disposed inexpensively and easily. Furthermore, electroless plating can more evenly distribute the thickness of the side and top surfaces of the wiring, thereby improving corrosion resistance on the side surfaces of the wiring compared to sputtering. Furthermore, the high deposition rates of electroless plating and electrolytic plating enable the formation of layers with low density and resistance to fracture. Note that, because gold has low wettability on the surface of copper, it is difficult to dispose the gold layer 73 by electroless plating so that it comes into contact with the copper layer 32. In this embodiment, the second layer 71 and the palladium layer 72 are disposed before disposing the gold layer 73, so that the gold layer 73 can be disposed stably.

[0062] When the second conductive layer 33 is disposed by electroless plating, the ends of the first layer 41, the second layer 71, and the palladium layer 72 may not be exposed, as shown in Fig. 12B. In the example shown in Fig. 12B, the end of the first layer 41 is covered with the second layer 71, the end of the second layer 71 is covered with the palladium layer 72, and the end of the palladium layer 72 is covered with the gold layer 73. By covering the first layer 41, the second layer 71, and the palladium layer 72 with the gold layer 73 in this way, corrosion resistance can be further improved.

[0063] In this manner, the substrate 10 having the base body 11 and the conductive member 12 can be manufactured.

[0064] A light emitting device is manufactured using the substrate 10. Figures 13A, 13B, 13C, and 13D are partial cross-sectional views illustrating the manufacturing process of the light emitting device according to this embodiment.

[0065] First, as shown in Fig. 13A, a light emitting element 20 having an upper surface 20a, a lower surface 20b, and a plurality of side surfaces 20c continuous with the upper surface 20a and the lower surface 20b, and a substrate 10 are prepared. In the example shown in Fig. 13A, a plurality of light emitting elements 20 are prepared. Then, as shown in Fig. 13B, the plurality of light emitting elements 20 are arranged on the substrate 10. Each light emitting element 20 is flip-chip mounted on the substrate 10 via gold bumps, which are conductive bonding members 25, with the surface on which the electrodes are arranged facing the conductive member 12.

[0066] Next, the light-transmitting member 50 is placed on the light-emitting element 20. In the example shown in Fig. 13C, one light-transmitting member 50 is placed on each of the plurality of light-emitting elements 20. In this embodiment, the light-transmitting member 50 is placed on the upper surface 20a of the light-emitting element 20 via an adhesive resin. Note that the light-transmitting member 50 may be placed on the upper surface of the light-emitting element 20 by a direct bonding method such as pressure bonding, surface activated bonding, atomic diffusion bonding, or hydroxyl group bonding, without using a bonding member such as an adhesive resin.

[0067] Next, as shown in FIG. 13D , a covering member 60 is placed on the substrate 10 to collectively cover the side surfaces 50 c of each light-transmitting member 50 and the side surfaces 20 c of each light-emitting element 20. Specifically, uncured resin that will become the covering member 60 is dispensed. First, the uncured resin is placed so as to form a substantially rectangular frame that surrounds the plurality of light-emitting elements 20 in a top view. At this time, the substantially rectangular frame is formed so as to include the outer edge of the first region 91 (i.e., the region that will become the outer edge of the covering member 60). Next, uncured resin is placed near the outer periphery of the plurality of light-emitting elements 20. At this time, the uncured resin spreads by capillary action to cover the lower surfaces 20 b of the light-emitting elements 20 and the conductive bonding member 25. Then, uncured resin is placed so as to cover the side surfaces 50 c of each light-transmitting member 50 and the side surfaces 20 c of each light-emitting element 20. At this time, the amount of uncured resin is adjusted so that the upper surface of the uncured resin covering the side surface 20c of the light-emitting element 20 and the upper surface 50a of the light-transmitting member 50 are substantially flush with each other. The uncured resin is then cured to form the covering member 60. As a result, as shown in FIG. 5, the substrate 10 is formed, including a first region 91 where the covering member 60 is to be disposed and a second region 92 exposed from the covering member 60. Finally, as shown in FIGS. 1 and 2, the substrate 10 and the covering member 60 are cut with a dicer so as to include a desired number of light-emitting elements 20, thereby obtaining individual light-emitting devices 1.

[0068] In this manner, the light emitting device 1 according to the embodiment can be manufactured.

[0069] The above describes preferred embodiments in detail, but the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the claims.

[0070] In addition to the above embodiments, the following supplementary notes are further disclosed. (Supplementary Note 1) A substrate comprising: a base having a main surface; and a conductive member disposed on the main surface, wherein the conductive member has: a first portion having a first conductive layer, a copper layer, and a second conductive layer stacked in this order from below; and a second portion having the first conductive layer and the second conductive layer stacked in this order from below, wherein the width of the second portion obtained by subtracting the thickness of the second conductive layer in a cross section passing through the first portion and the second portion is 99 μm or more and 1998.9 μm or less. (Supplementary Note 2) The substrate according to Supplementary Note 1, wherein each of the first conductive layer and the second conductive layer has a higher halogen resistance than the halogen resistance of the copper layer. (Supplementary Note 3) The substrate according to Supplementary Note 1 or 2, wherein the first conductive layer has a first layer containing titanium, and the second conductive layer has a second layer containing nickel, and the first layer and the second layer are in contact with each other. (Supplementary Note 4) The substrate according to any one of Supplementary Notes 1 to 3, wherein the first conductive layer has a first layer containing titanium, the base includes a nitride ceramic, and the first layer and the base are in contact with each other. (Supplementary Note 5) The substrate according to Supplementary Note 3 or 4, wherein the first layer contains a titanium-tungsten alloy. (Supplementary Note 6) The substrate according to any one of Supplementary Notes 1 to 5, wherein the copper layer has a thickness of 1 μm or more and 90 μm or less. (Supplementary Note 7) A light-emitting device comprising: a light-emitting element, a covering member, and the substrate according to any one of Supplementary Notes 1 to 6. (Supplementary Note 8) The light-emitting device according to Supplementary Note 7, wherein a first boundary between the first portion and the second portion is covered by the covering member. (Supplementary Note 9) The light-emitting device according to Supplementary Note 8, wherein a main surface of the substrate has: a first region in which the covering member is arranged; and a second region exposed from the covering member, and a distance between the first boundary and a second boundary that is a boundary between the first region and the second region is 10 μm or more. (Supplementary Note 10) The light-emitting device according to Supplementary Note 9, wherein a distance from the second boundary to an outer edge of the second portion is 100 μm or more in a top view. (Supplementary Note 11) The light-emitting device according to any one of Supplementary Notes 7 to 10, wherein the light-emitting element is connected to the second conductive layer in the first portion and is covered with the covering member.

[0071] This application claims priority based on Japanese Patent Application No. 2024-072060 filed with the Japan Patent Office on April 26, 2024, and Japanese Patent Application No. 2025-010120 filed with the Japan Patent Office on January 23, 2025, and includes the entire contents of these Japanese patent applications.

[0072] REFERENCE SIGNS LIST 1 Light emitting device 10 Substrate 11 Base body 11A Upper surface 12 Conductive member 20 Light emitting element 31 First conductive layer 32 Copper layer 33 Second conductive layer 41 First layer 42 Seed layer 50 Light-transmitting member 60 Covering member 71 Second layer 72 Palladium layer 73 Gold layer 81 First portion 82 Second portion 83 First boundary 91 First region 92 Second region 93 Second boundary 110 Mask 120 Mask

Claims

1. A substrate comprising: a base having a principal surface; and a conductive member disposed on said principal surface, wherein said conductive member has: a first portion having a first conductive layer, a copper layer, and a second conductive layer laminated in that order from below; and a second portion having said first conductive layer and said second conductive layer laminated in that order from below, wherein the width of said second portion, obtained by subtracting the thickness of said second conductive layer, in a cross section passing through said first portion and said second portion is 99 μm or more and 1998.9 μm or less.

2. The substrate of claim 1, wherein the first conductive layer and the second conductive layer each have a higher halogen resistance than the copper layer.

3. The substrate of claim 1 or 2, wherein the first conductive layer has a first layer containing titanium, and the second conductive layer has a second layer containing nickel, and the first layer and the second layer are in contact with each other.

4. The substrate according to any one of claims 1 to 3, wherein the first conductive layer has a first layer containing titanium, the substrate comprises a nitride ceramic, and the first layer and the substrate are in contact with each other.

5. The substrate of claim 3 or 4, wherein the first layer comprises a titanium tungsten alloy.

6. The substrate according to any one of claims 1 to 5, wherein the copper layer has a thickness of 1 μm or more and 90 μm or less.

7. A light emitting device comprising: a light emitting element; a covering member; and the substrate according to any one of claims 1 to 6.

8. The light emitting device according to claim 7, wherein a first boundary between the first portion and the second portion is covered by the covering member.

9. The light-emitting device according to claim 8, wherein the main surface of the substrate has a first region in which the covering member is disposed and a second region exposed from the covering member, and the distance between the first boundary and a second boundary between the first region and the second region is 10 μm or more.

10. The light emitting device according to claim 9, wherein the distance from the second boundary to the outer edge of the second portion is 100 μm or more when viewed from above.

11. The light emitting device according to any one of claims 7 to 10, wherein the light emitting element is connected to the second conductive layer at the first portion and is covered by the covering member.

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