Light-emitting device and method for producing light-emitting device

Abstract

The present disclosure provides a light-emitting device comprising a light reflection member with high heat dissipation. The light-emitting device according to the present disclosure includes: a light-emitting element including a semiconductor structure that has a light-emitting surface, an electrode formation surface on the opposite side of the light-emitting surface, and a side surface positioned between the light-emitting surface and the electrode formation surface, and an electrode provided on the electrode formation surface; and a light reflection member having a lower surface and covering the side surface of the semiconductor structure and the side surface of the electrode. The electrode has an exposed surface not covered by the light reflection member, and the light reflection member includes: a first light reflection part that covers a side surface of the semiconductor structure and includes an inorganic material serving as a main material, and a light reflection material having a refractive index higher than that of the inorganic material; and a second light reflection part that has a lower surface, covers at least a portion of the side surface of the electrode, includes an inorganic material, and includes or substantially does not include a light reflection material in a content smaller than that of the first light reflection part.

Description

Light emitting device and method for manufacturing the same

[0001] The present disclosure relates to a light emitting device and a method for manufacturing a light emitting device.

[0002] In recent years, light sources using light-emitting elements such as light-emitting diodes have come into widespread use. For example, Patent Document 1 discloses a light-emitting device in which at least the side surfaces of the light-emitting element are covered with a light-reflective covering member and a phosphor layer is disposed on the upper surface of the light-emitting element.

[0003] JP 2018-14480 A

[0004] However, there is still room for improvement in the light-reflective covering member in order to improve the performance of the light-emitting device. For example, the covering member that covers the light-emitting element generates heat when irradiated with light from the light-emitting element, so there is a need for further improvement in heat dissipation.

[0005] Therefore, an object of the present disclosure is to provide a light emitting device having a light reflecting member with high heat dissipation properties, and a method for manufacturing the light emitting device.

[0006] a light-emitting element including a semiconductor structure having a light-emitting surface, an electrode-forming surface opposite the light-emitting surface, and a side surface located between the light-emitting surface and the electrode-forming surface, and an electrode provided on the electrode-forming surface; a light-reflecting member having a lower surface and covering the side surface of the semiconductor structure and the side surface of the electrode, wherein the electrode has an exposed surface that is not covered by the light-reflecting member, and the light-reflecting member includes: a first light-reflecting portion covering the side surface of the semiconductor structure and comprising an inorganic material that is a main material and a light-reflecting material having a refractive index higher than that of the inorganic material; and a second light-reflecting portion having the lower surface and covering at least a portion of the side surface of the electrode, comprising the inorganic material and containing the light-reflecting material in a content lower than that of the first light-reflecting portion or being substantially free of the light-reflecting material.

[0007] A method for manufacturing a light-emitting device according to the present disclosure includes the steps of: preparing a light-emitting element including a semiconductor structure having a light-emitting surface, an electrode-forming surface opposite the light-emitting surface, and a side surface located between the light-emitting surface and the electrode-forming surface; and an electrode provided on the electrode-forming surface; preparing a light-reflecting inorganic member having a first light-reflecting portion made of an inorganic material containing a light-reflecting material and having plasticity, and a second light-reflecting portion made of an inorganic material containing a light-reflecting material in a smaller content than the first light-reflecting portion or containing substantially no light-reflecting material, and having plasticity, the second light-reflecting portion being disposed below the first light-reflecting portion; and pressing the electrode-forming surface of the light-emitting element by contacting the electrode with the first light-reflecting portion from the first light-reflecting portion side of the light-reflecting inorganic member, causing the side surface of the semiconductor structure and the electrode-forming surface to sink so that the first light-reflecting portion covers the electrode-forming surface.

[0008] According to the present disclosure, it is possible to provide a light emitting device having a light reflecting member with high heat dissipation properties, and a method for manufacturing the light emitting device.

[0009] 1 is a schematic cross-sectional view of a light-emitting device according to an embodiment of the present disclosure; FIG. 1 is a schematic cross-sectional view of a light-emitting device according to a modified example of the present disclosure; FIG. 2 is a schematic cross-sectional view showing an enlarged boundary portion between a first light reflecting portion and a second light reflecting portion in a light-emitting device according to an embodiment of the present disclosure; FIG. 3 is a schematic cross-sectional view of a step in a manufacturing method for a light-emitting device according to the present disclosure; FIG. 4 is a schematic cross-sectional view of a step in a manufacturing method for a light-emitting device according to the present disclosure; FIG. 5 is a schematic cross-sectional view of a step in a manufacturing method for a light-emitting device according to the present disclosure; FIG. 6 is a schematic cross-sectional view of a step in a manufacturing method for a light-emitting device according to the present disclosure;

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the light emitting device and the method for manufacturing the light emitting device described below are intended to embody the technical concept of the present disclosure, and unless otherwise specified, the present disclosure is not limited to the following.

[0011] In each drawing, components having the same function may be given the same symbol. For convenience, the embodiments may be shown in multiple parts to facilitate explanation or understanding of the main points, but partial substitution or combination of the configurations shown in different embodiments is possible. In the embodiments described below, descriptions of matters common to the above will be omitted, and only the differences will be described. In particular, similar effects due to similar configurations will not be mentioned in each embodiment. The size and positional relationship of components shown in each drawing may be exaggerated to clarify the explanation. Cross-sectional views may be used in which only the cut surface is shown.

[0012] <Embodiment of Light-Emitting Device> A light-emitting device 1 according to an embodiment of the present disclosure will be described in detail with reference to Fig. 1. The light-emitting device 1 according to the embodiment of the present disclosure includes at least a light-emitting element 10 and a light-reflecting member 20.

[0013] The light-emitting element 10 includes a semiconductor structure 11 and a first electrode 12. The semiconductor structure 11 has a light-emitting surface 11a, an electrode-forming surface 11b located opposite the light-emitting surface 11a, and a side surface 11c located between the light-emitting surface 11a and the electrode-forming surface 11b. The first electrode 12 is disposed on the electrode-forming surface 11b and has a first surface 12a facing the electrode-forming surface 11b, a second surface 12b located opposite the first surface 12a, and a side surface 12c located between the first surface 12a and the second surface 12b.

[0014] The light reflecting member 20 covers the light emitting element 10 except for the light emitting surface 11 a and the second surface 12 b. Furthermore, the light reflecting member 20 includes a first light reflecting portion 21 that covers at least the side surface 11 c of the semiconductor structure 11, and a second light reflecting portion 22 that covers at least a part of the side surface 12 c of the first electrode 12 on the second surface 12 b side and the lower surface of the first light reflecting portion 21.

[0015] Hereinafter, each component of the light-emitting device 1 according to the embodiment of the present disclosure will be described in detail with reference to Fig. 1 and Fig. 3. Here, Fig. 1 and Fig. 3 illustrate the light-transmitting member 30 and the second electrode 13, but the invention of the present disclosure may or may not include the light-transmitting member 30 and the second electrode 13. When the light-emitting device 1 includes the light-transmitting member 30, the upper surface 30a of the light-transmitting member 30 functions as the light-emitting surface of the light-emitting device 1.

[0016] [Light-emitting element] The light-emitting element 10 can be a semiconductor light-emitting element such as a light-emitting diode, and can be a light-emitting element 10 capable of emitting ultraviolet light or visible light such as blue, green, or red. The light-emitting element 10 includes a semiconductor structure 11 including a light-emitting layer, and a first electrode 12. The semiconductor structure 11 includes a surface on the side where the first electrode 12 is formed (electrode formation surface) and a light extraction surface (light-emitting surface) on the opposite side.

[0017] The semiconductor structure 11 includes semiconductor layers including a light-emitting layer. Furthermore, the semiconductor structure 11 may include a light-transmitting substrate such as sapphire on the light-emitting surface 11a side of the semiconductor structure 11. As an example, the semiconductor structure 11 may include three semiconductor layers: a first conductivity type semiconductor layer (e.g., an n-type semiconductor layer), a light-emitting layer (active layer), and a second conductivity type semiconductor layer (e.g., a p-type semiconductor layer). The semiconductor layer capable of emitting ultraviolet light and visible light ranging from blue light to green light can be formed from a semiconductor material such as a III-V group compound semiconductor. Specifically, In Ｘ Al Ｙ Ga １－Ｘ－Ｙ Nitride-based semiconductor materials such as N (0≦X, 0≦Y, X+Y≦1) can be used. Furthermore, semiconductor layers capable of emitting red light can be made of GaAs, GaAlAs, GaP, InGaAs, InGaAsP, etc. The peak wavelength of light emitted from the semiconductor structure 11 may be, for example, in the range of 260 nm to 630 nm.

[0018] The first electrode 12 includes, for example, a negative electrode and a positive electrode, and is disposed on the same side (electrode formation surface) of the semiconductor structure 11. The first electrode 12 has a first surface 12a facing the electrode formation surface 11b of the semiconductor structure 11, a second surface 12b located opposite the first surface 12a, and a side surface 12c located between the first surface 12a and the second surface 12b. Each of the negative electrode and the positive electrode included in the first electrode 12 may have a single-layer structure or a multilayer structure. Such a first electrode 12 can be formed to any thickness using materials and configurations known in the art. For example, the thickness of the first electrode 12 is preferably between 10 and 300 μm. Furthermore, a good conductor can be used for the first electrode 12, and a metal such as Cu is suitable. Various electrode shapes can be selected depending on the purpose and application.

[0019] [Light-Reflecting Member] The light-reflecting member 20 covers the side surface 11c of the semiconductor structure 11 and the side surface 12c of the first electrode 12, exposing the second surface 12b of the first electrode 12 from the underside of the light-reflecting member 20. If the light-emitting device 1 includes a light-transmitting member 30, the light-reflecting member 20 also covers, for example, the side surface of the light-transmitting member 30. In this specification, the second surface 12b of the first electrode 12 is also referred to as the exposed surface. In the light-emitting device 1 of this embodiment, the light-reflecting member 20 is made of an inorganic material, which provides higher heat resistance than light-reflecting members primarily made of resin, thereby improving reliability even when applied to light-emitting devices with high light emission intensity. Furthermore, inorganic materials are less susceptible to photodegradation than resins, and can particularly suppress photodegradation when applied to light-emitting devices using light-emitting elements 10 that emit ultraviolet light, which has higher energy than visible light. The peak wavelength of the light-emitting elements 10 that emit ultraviolet light is, for example, 410 nm or less. Furthermore, inorganic materials have higher thermal conductivity than organic materials and have good heat dissipation properties, so they can properly dissipate heat toward the outside of the first light reflecting portion 21 (e.g., toward the second light reflecting portion 22 or the translucent member 30), thereby improving heat dissipation properties.

[0020] In the light-emitting device 1 of this embodiment, the lower surface of the light-reflecting member 20 is the mounting surface side, and the second surface (exposed surface) 12b of the first electrode 12 exposed from the lower surface of the light-reflecting member 20 is connected to an electrode of the mounting substrate, for example, directly or via the second electrode 13, which is an auxiliary electrode. In the light-emitting device 1, the mounting surface may be subjected to various processes during manufacturing, as described in the manufacturing method described below. Furthermore, even after manufacturing, the light-emitting device 1 may be subjected to force or heat, for example, during mounting. Therefore, in the light-emitting device 1 of this embodiment, the light-reflecting member 20 includes a first light-reflecting portion 21 located on the light-emitting surface 11a side and covering the side surface 11c of the semiconductor structure 11 and, if a light-transmitting member 30 is included, the side surface of the light-transmitting member 30, and a second light-reflecting portion 22 located on the mounting surface side. The side surface of the light-reflecting member 20 includes a first side surface 21c of the first light-reflecting portion 21 and a second side surface 22c of the second light-reflecting portion 22 located below the first side surface 21c. The first light reflecting portion 21 is composed of an inorganic material as a main material and a light reflecting material having a refractive index higher than that of the inorganic material. The second light reflecting portion 22 is composed of an inorganic material as a main material and a light reflecting material in a smaller content than the first light reflecting portion 21, or is composed of substantially no light reflecting material. The second light reflecting portion 22 may, for example, contain the same inorganic material as the first light reflecting portion 21 as a main inorganic material. The second light reflecting portion 22 is located on the mounting surface side, constitutes the lower surface of the light reflecting member 20, and covers at least a portion of the side surface 12c of the electrode 12. The first light reflecting portion 21 and the second light reflecting portion 22 will be described in more detail below.

[0021] The first light reflecting portion 21 has a higher reflectivity than the second light reflecting portion 22 and more effectively reflects light emitted from the light emitting element 10. The first light reflecting portion 21 can, for example, reflect light from the light emitting element 10 at a reflectivity of 70% or more. The first light reflecting portion 21 is a member primarily composed of an inorganic material. The first light reflecting portion 21 includes an inorganic light reflecting material (filler) and a support material made of an inorganic material that supports the light reflecting material. In addition to improving reflectivity, the light reflecting material can suppress shrinkage due to, for example, heating during manufacturing and prevent cracking. After manufacturing, the light reflecting material also functions as an aggregate that prevents deformation and cracking due to heat. This aggregate function can be more effectively achieved by, for example, being plate-shaped or needle-shaped particles. Examples of light reflecting materials include at least one selected from boron nitride, silicon nitride, aluminum nitride, and aluminum oxide. Among these, boron nitride has high heat dissipation properties and can efficiently dissipate heat generated by the light emitting element. In this way, by including a light-reflecting material that can function as an aggregate, the first light-reflecting portion 21 can not only increase the light reflectivity, but also improve the quality of the first light-reflecting portion 21 during and after manufacturing.

[0022] Hereinafter, the light-reflecting material, which is a plate-like or needle-like particle, will be specifically described with reference to Fig. 3. Fig. 3 is a cross-sectional view schematically showing a part of a cross section of a light-reflecting member 20 in which a support material 212 made of silicon oxide (silica) contains a light-reflecting material 211 made of boron nitride, with the part above the dashed line being the first light-reflecting portion 21 and the part below the dashed line being the second light-reflecting portion 22. Fig. 3 shows an example in which the second light-reflecting portion 22 does not substantially contain the light-reflecting material 211.

[0023] The plate-shaped or needle-shaped light-reflecting material 211 is not limited to boron nitride, and may be, for example, silicon nitride, aluminum nitride, or aluminum oxide. The light-reflecting material 211 may be primary particles or secondary particles formed by agglomeration of two or more primary particles. Primary particles and secondary particles may also be mixed. The plate-shaped or needle-shaped light-reflecting material 211 refers to a case where the average aspect ratio of the light-reflecting material 211 in the cross section of the first light-reflecting portion 21 is 5 or more. The average aspect ratio is preferably 10 or more, and more preferably 10 to 70. By using such a plate-shaped or needle-shaped light-reflecting material 211, deformation of the first light-reflecting portion 21 can be more effectively suppressed. The plate-shaped light-reflecting material 211 includes a scale-shaped light-reflecting material, which will be described later.

[0024] <Method for Calculating Average Aspect Ratio> The average aspect ratio of the light reflecting material 211 is calculated by measuring the thickness and width of the light reflecting material 211 included in the cross section of the first light reflecting portion 21. First, the light emitting device is cut in a direction approximately perpendicular to the light emitting surface to form a cross section of the first light reflecting portion 21. Next, the exposed cross section is mirror-polished. The mirror-polished cross section is photographed using a scanning electron microscope (SEM). Then, a measurement area including the cross sections of approximately 1,000 light reflecting materials 211 is selected. Here, the number of pixels of the microscope is set to approximately 20 million, and the magnification is set to 500x to 3,000x. Note that due to their shape, the plate-shaped or needle-shaped light reflecting materials 211 tend to be arranged overlapping each other within the first light reflecting portion 21.

[0025] Next, the width (length in the longitudinal direction of the cross section of the light reflecting material) and thickness (length in the lateral direction of the cross section of the light reflecting material) of each cross section of the extracted light reflecting material 211 are measured one by one using image analysis software, and the ratio of the width to the thickness is calculated. The average value of the calculated values ​​of the measured light reflecting material 211 is then taken as the average aspect ratio.

[0026] The average particle size of the light reflecting material 211 is preferably 0.6 μm or more and 43 μm or less, and more preferably 2 μm or more and 20 μm or less. When the light reflecting material 211 is boron nitride, the average particle size of the light reflecting material 211 is, for example, 6 μm or more and 43 μm or less. When the light reflecting material 211 is aluminum oxide, the average particle size of the light reflecting material 211 is, for example, 0.6 μm or more and 10 μm or less. The average particle size of the light reflecting material 211 can be calculated as follows. Note that the particle size of the light reflecting material 211 calculated by the method for calculating the average particle size described below is the particle size of the powder used as the raw material for the light reflecting material 211 when forming the first light reflecting section 21. However, the particle size of the raw material for the light reflecting material 211 is not substantially different from the particle size of the light reflecting material 211 contained after the first light reflecting section 21 is formed. The average particle size of the light reflecting material 211 contained in the first light reflecting section 21 can be measured by the following method.

[0027] <Method of Calculating Average Particle Size> The particle size of the powder of the light reflecting material 211 is calculated using, for example, a scanning electron microscope "TM3030Plus" manufactured by Hitachi High-Technologies Corporation. First, one side of a double-sided carbon tape is attached to the microscope's sample stage, and then the powder of the light reflecting material 211 is placed on the other side of the double-sided tape. The microscope's pixel count is set to 1.23 million pixels, and the magnification is set to 1000x to 2000x to acquire images of 100 powder (particles) of the light reflecting material 211. Then, the particle size of each particle is measured using image analysis software. In this specification, the particle size of the powder of the light reflecting material 211 is the largest diameter among the diameters on the main surface of the light reflecting material 211. Next, the median diameter of the measured particles is calculated, and this calculated value is used as the average particle size of the light reflecting material 211. Alternatively, the particle size of the powder of the light reflecting material 211 may be calculated by measuring the cross section of the first light reflecting portion 21 using an SEM and image analysis software.

[0028] The first light reflecting portion 21 can be formed into a desired shape by supporting the light reflecting material with a support material made of an inorganic material. An example of a support material is an inorganic polymer containing potassium hydroxide mixed with at least one selected from aluminum oxide, calcium oxide, and silicon oxide. The potassium hydroxide contained in the support material is a mixture of an aqueous solution of potassium hydroxide. When the water contained in this aqueous solution evaporates, voids are dispersed and formed within the first light reflecting portion 21, thereby suppressing shrinkage during formation. Preferably, the light reflecting material 211 and the support material are mixed so that the volume of the light reflecting material 211 is 0.5 to 5 times the volume of the support material. This range reduces shrinkage during hardening of the mixture. Furthermore, the average particle size of the support material is preferably smaller than that of the light reflecting material 211. By setting this particle size, voids that form between the fillers during mixing can be filled with the support material. The average particle size of the support material can be calculated by measuring the particle size distribution using a laser diffraction method.

[0029] The light reflecting material 211 and the support material are mixed with, for example, an alkaline solution containing an alkali metal, and then formed through a process such as heating. That is, the first light reflecting section 21 may contain an alkali metal resulting from the alkaline solution. Examples of alkali metals contained in the alkaline solution include potassium and / or sodium. When the light reflecting material 211 and the support material are mixed with the alkaline solution, the light reflecting material 211 can be appropriately dispersed in the first light reflecting section 21.

[0030] The first light reflecting portion 21 may further include a light scattering material. The light scattering material is, for example, primarily zirconium oxide or titanium oxide. When the light-emitting element emits ultraviolet light, zirconium oxide is preferred because it has low light absorption in the ultraviolet wavelength region. By including a light scattering material in the first light reflecting portion 21, the light reflectance of the first light reflecting portion 21 is improved. This allows for a sharper difference in brightness between the light-emitting surface of the light-emitting device 1 and the upper surface 20a (non-light-emitting surface) of the light-reflecting member 20 that surrounds the light-emitting surface in a top view. In other words, the visibility of the light-emitting surface side of the light-emitting device 1 can be improved. The light scattering material may be titanium oxide alone, or titanium oxide coated with a coating film composed of one or more of silica, aluminum oxide, zirconium oxide, zinc, organic materials, etc. The light scattering material may be zirconium oxide alone, or may be zirconium oxide covered on its surface with a coating film composed of one or more of silica, aluminum oxide, zinc, organic materials, etc. Alternatively, stabilized zirconium oxide or partially stabilized zirconium oxide to which calcium, magnesium, yttrium, aluminum, etc. have been added may be used.

[0031] As described above, the second light reflecting portion 22 contains an inorganic material and is configured to contain a light reflecting material at a lower content than the first light reflecting portion 21 or to be substantially free of light reflecting material, and is disposed on the mounting surface side of the light emitting device. This allows for improved quality on the mounting surface side compared to when the lower surface of the first light reflecting portion 21 is used as the mounting surface of the light emitting device. As described above, the light reflecting material 211 contained in the first light reflecting portion 21 improves reflectivity and also functions as an aggregate. However, the inventors have discovered that increasing the content of the light reflecting material to achieve a desired reflectivity creates new issues on the mounting surface side. One issue is that increasing the content of the light reflecting material (aggregate) tends to make the substrate less susceptible to elastic deformation, which can lead to chipping or cracking when attempting to grind the mounting surface side during manufacturing. Another issue is that when forming a second electrode as an auxiliary electrode, sufficient adhesion with the second electrode may not be achieved.

[0032] Therefore, in this embodiment, a second light reflecting portion 22 containing an inorganic material and configured to contain a light reflecting material at a lower content than the first light reflecting portion 21 or to be substantially free of light reflecting material is disposed on the mounting surface side of the light emitting device. This makes it possible to solve new problems that arise on the mounting surface side when the light reflecting member 20 is configured from an inorganic material. The second light reflecting portion 22 can be configured using a support material made of an inorganic material exemplified for the first light reflecting portion 21, and a light reflecting material 211 made of an inorganic material exemplified for the first light reflecting portion 21. The support material and light reflecting material of the second light reflecting portion 22 may be the same as or different from those of the first light reflecting portion 21.

[0033] However, it is preferable that the support material of the first light reflecting portion 21 and the support material of the second light reflecting portion 22 are the same inorganic material, which can increase the bonding strength at the interface between the second light reflecting portion 22 and the first light reflecting portion 21.

[0034] Furthermore, by selecting an inorganic material that can effectively function as an aggregate for the light reflecting material 211 contained in the first light reflecting portion 21, and selecting an inorganic material that can improve the quality of the mounting surface side compared to the first light reflecting portion 21 for the light reflecting material 211 contained in the second light reflecting portion 22, the functions required of each light reflecting portion can be effectively exhibited. For example, by selecting a plate-like or needle-shaped inorganic material that can effectively function as an aggregate for the light reflecting material 211 contained in the first light reflecting portion 21, and selecting a spherical inorganic material that has poor aggregate function for the light reflecting material contained in the second light reflecting portion 22, the functions required of each reflecting portion can be effectively exhibited. Furthermore, the second light reflecting portion 22 may contain a light scattering material similar to that exemplified for the first light reflecting portion 21. As the light scattering material, the same light scattering materials as those exemplified for the first light reflecting portion 21 can be used.

[0035] [Light-Transmitting Member] In the light-emitting device 1, a light-transmitting member 30 may be disposed on the light-emitting surface 11a of the light-emitting element 10. The light-transmitting member 30 may be a molded body made of, for example, a resin material, ceramics, glass, or the like.

[0036] The resin material of the light-transmitting member 30 is preferably a light-transmitting resin. Examples of the resin material that can be used for the light-transmitting resin include thermosetting resins such as silicone resin, silicone-modified resin, epoxy resin, and phenolic resin, and thermoplastic resins such as polycarbonate resin, acrylic resin, methylpentene resin, and polynorbornene resin. Silicone resin, which has excellent light resistance and heat resistance, is particularly suitable.

[0037] Furthermore, the light-transmitting member 30 may include a light diffusing member that diffuses the light from the light-emitting element 10. The light diffusing member may include, for example, titanium oxide, barium titanate, aluminum oxide, silicon oxide, or the like.

[0038] In the light emitting device 1, the light-transmitting member 30 does not need to be disposed on the light emitting surface 11a of the light emitting element 10. In this case, the upper surface of the first light reflecting portion 21 and the light emitting surface 11a of the light emitting element 10 form the upper surface of the light emitting device 1. By not disposing the light-transmitting member 30 on the light emitting surface 11a side of the light emitting element 10, the light emitting device 1 can be made smaller.

[0039] The light-transmitting member 30 may further contain a wavelength conversion material. Examples of the wavelength conversion material include yttrium aluminum garnet phosphors (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 ) and the like can be used. Furthermore, one of these wavelength converting substances can be used alone, or two or more of these wavelength converting substances can be used in combination.

[0040] Examples of the light-transmitting member 30 containing a wavelength converting material include resin materials, ceramics, glass, etc., containing particles of the wavelength converting material, or sintered bodies of the wavelength converting materials. The light-transmitting member 30 may also be a molded body of a resin material, ceramics, glass, etc., on one surface of which a resin material containing particles of the wavelength converting material is disposed.

[0041] As shown in Figures 1 and 3, the side of the translucent member 30 is covered, for example, by the first light reflecting portion 21, but it may not be covered by the first light reflecting portion 21 and may be flush with the side of the light reflecting member 20, for example, to form the outer surface of the light emitting device 1.

[0042] [Second Electrode] The light emitting device 1 may have a second electrode 13 bonded to the second surface 12b of the first electrode 12. The second electrode 13 may be provided extending from the second surface 12b to the outer surface of the second light reflecting portion 22.

[0043] The second electrode 13 mainly functions as an external electrode of the light emitting device 1. It is preferable to select a material for the second electrode 13 that has better corrosion resistance and oxidation resistance than the first electrode 12. For example, the outermost layer is preferably made of Au or a platinum group metal such as Pt. Note that, in consideration of mounting the light emitting device 1 using solder, it is preferable to use Au, which has good solderability, for the outermost surface of the second electrode 13.

[0044] The second electrode 13 may be composed of only one layer of a single material, or may be composed of a laminate of layers of different materials. It is particularly preferable to use a second electrode 13 with a high melting point, such as Ru, Mo, Ta, or W. Furthermore, by providing such a high-melting-point metal between the first electrode 12 and the outermost layer of the light-emitting element 10, a diffusion prevention layer can be formed that can reduce the diffusion of Sn contained in the solder into the first electrode 12 or layers close to the first electrode 12. Examples of laminate structures that include such a diffusion prevention layer include Ni / Ru / Au and Ti / Pt / Au. Furthermore, the thickness of the diffusion prevention layer (e.g., Ru) is preferably approximately 10 Å to 1000 Å.

[0045] As described above, according to the light emitting device 1 of the embodiment of the present disclosure, the provision of the light reflecting member 20 can improve heat resistance characteristics. Furthermore, the provision of the second light reflecting portion 22 can reduce deformation of the first light reflecting portion 21 that occurs during processing during the manufacture of the light emitting device 1. As an example, in the "electrode exposing step" described below, the first light reflecting portion 21 is covered with the second light reflecting portion 22, so that the effect of processing on the first light reflecting portion 21 can be reduced.

[0046] Next, a method for manufacturing a light emitting device according to an embodiment of the present disclosure will be described. The method for manufacturing a light emitting device 1 according to the present disclosure includes the steps of: preparing a light emitting element 10 including a semiconductor structure 11 having a light emitting surface 11a, an electrode forming surface 11b opposite to the light emitting surface 11a, and a side surface 11c located between the light emitting surface 11a and the electrode forming surface 11b, and a first electrode 12 provided on the electrode forming surface 11b; preparing a light reflecting member 20 having a first light reflecting portion 21s made of an inorganic material containing a light reflector 211 and having plasticity, and a second light reflecting portion 22s made of an inorganic material containing the light reflector 211 in a content less than that of the first light reflecting portion 21s or substantially not containing the light reflector 211, and having plasticity, the second light reflecting portion 22s being disposed below the first light reflecting portion 21s; and pressing the electrode 12 against the first light reflecting portion 21s of the light reflecting member 20 from the first light reflecting portion 21s side, thereby sinking the electrode forming surface 11b of the light emitting element 10 so that the side surface 11c of the semiconductor structure 11 and the electrode forming surface 11b are covered by the first light reflecting portion 21s. The method may further include a "step of preparing and arranging a light-transmitting member 30," a "step of exposing the first electrode 12," and a "step of forming a second electrode 13." Note that either the "step of preparing the light emitting element 10" or the "step of preparing the light reflecting member 20" may be performed first, or they may be performed in parallel. Furthermore, the optional "step of arranging the light-transmitting member 30" is performed between the "step of preparing the light emitting element 10" and the "sinking step," and the "step of exposing the first electrode 12" and the "step of forming the second electrode 13" are performed after the "sinking step." The method for manufacturing the light emitting device 1 according to the present disclosure will be described in detail below, including optional steps. Note that the optional steps are also illustrated in Figures 4 to 10, which are referred to in the following description.

[0047] [Step of preparing light-emitting element 10] First, a light-emitting element 10 is prepared, which includes a semiconductor structure 11 having a light-emitting surface 11 a and an electrode-forming surface 11 b located opposite the light-emitting surface 11 a, and a first electrode 12 arranged on the electrode-forming surface 11 b and having a first surface 12 a facing the electrode-forming surface 11 b, a second surface 12 b located opposite the first surface 12 a, and a side surface 12 c located between the first surface 12 a and the second surface 12 b.

[0048] [Step of Preparing and Arranging the Light-Transmitting Member 30] When the light-transmitting member 30 is included, the light-transmitting member 30 is prepared and the light-emitting element 10 is arranged on the light-transmitting member 30. The light-transmitting member 30 contains a wavelength conversion material such as a YAG phosphor, and may include a light-diffusing member as described above. The light-diffusing member is titanium oxide, barium titanate, aluminum oxide, silicon oxide, or the like.

[0049] [Step of Preparing Light Reflecting Member 20] The step of preparing the light reflecting member 20 further includes the steps of: preparing a first light reflecting portion 21s made of an inorganic material containing a light reflecting material 211 and having plasticity; preparing a second light reflecting portion 22s made of an inorganic material containing a light reflecting material 211 at a content lower than that of the first light reflecting portion 21s or substantially not containing the light reflecting material 211; and stacking and pressing the first light reflecting portion 21s having plasticity and the second light reflecting portion 22s having plasticity to prepare a light reflecting member 20 in which the first light reflecting portion 21s and the second light reflecting portion 22s are stacked. Below, the step of preparing the first light reflecting portion 21s, the step of preparing the second light reflecting portion 22s, and the step of preparing the light reflecting member 20 will be described in order. In each drawing, the sheet-like first light reflecting portion before division is denoted by the reference numeral 21s, and the sheet-like second light reflecting portion before division is denoted by the reference numeral 22s.

[0050] In the process of preparing the first light reflecting portion 21s, first, an inorganic material serving as the main material (support material 212) and a light reflecting material 211 having a refractive index higher than that of the inorganic material are mixed with an alkaline solution to prepare a first mixed material. Next, the first mixed material is pressed, for example, by press processing, to prepare the first light reflecting portion 21s of a predetermined thickness. Here, in the process of preparing the first mixed material, the mixing ratio of the inorganic material serving as the main material, the light reflecting material 211, and the alkaline solution, as well as the pressure applied in the press processing to prepare the first light reflecting portion 21s, are set so as to form the first light reflecting portion 21s of a predetermined thickness, taking into account deformation due to pressure applied in the process of preparing the light reflecting member 20, which will be described later. Furthermore, in the process of preparing the first mixed material, the mixture with the alkaline solution is mixed, for example, using a stirring / defoaming device capable of stirring under reduced pressure, until a uniform viscosity is obtained.

[0051] In the process of preparing the second light reflecting portion 22s, first, a second mixed material is prepared by mixing (i) only an inorganic material that will serve as the main material (support material 212) or (ii) an inorganic material that includes the inorganic material that will serve as the main material (support material 212) and a light reflecting material 211 in a content less than that of the first light reflecting portion 21s, with an alkaline solution. Next, the second mixed material is pressed, for example, by press processing, to prepare the second light reflecting portion 22s of a predetermined thickness. Here, in the process of preparing the second mixed material, the mixing ratio of the inorganic material that will serve as the main material or the inorganic material that includes the inorganic material that will serve as the main material (support material 212) and the light reflecting material 211, and the alkaline solution, the pressure applied in the press processing to prepare the second light reflecting portion 22s, and other factors are appropriately set in consideration of deformation due to pressurization in the process of preparing the light reflecting member 20, which will be described later, so that the second light reflecting portion 22s of a predetermined thickness is formed. The mixing with the alkaline solution in the step of preparing the second mixed material is carried out, for example, using a stirring defoamer or the like that can stir under reduced pressure, until a uniform viscosity is obtained.

[0052] In the process of preparing the light-reflecting member 20, as shown in FIG. 5 , the first light-reflecting portion 21s and the second light-reflecting portion 22s are stacked on top of each other and pressurized by pressing or the like to produce the light-reflecting member 20 in which the first light-reflecting portion 21s and the second light-reflecting portion 22s are laminated. Here, the first light-reflecting portion 21s tends to have higher plasticity (fluidity) because it contains more light-reflecting material 211 (aggregate) than the second light-reflecting portion 22s. As shown schematically in FIGS. 4 and 5 , the first light-reflecting portion 21s tends to become thinner than the second light-reflecting portion 22s due to pressurization. The degree of plasticity (fluidity) is also an important parameter in the process of sinking the light-emitting element 10 into the light-reflecting member 20, which will be described later. Therefore, it is preferable to set the plasticity of the first light-reflecting portion 21s and the second light-reflecting portion 22s, particularly the plasticity of the first light-reflecting portion 21s, taking into consideration the content of the light-reflecting material 211.

[0053] [Step of sinking the light-emitting element 10 into the light-reflecting member 20] In the step of sinking the light-emitting element 10 into the light-reflecting member 20, the electrode-forming surface 11b of the light-emitting element 10 is brought into contact with the first light-reflecting portion 21s of the light-reflecting member 20 from the first light-reflecting portion 21s side and pressed, and the side surface 11c and the electrode-forming surface 11b of the semiconductor structure 11 are sunk into the light-reflecting member 20 so that the first light-reflecting portion 21s covers the side surface 11c and the electrode-forming surface 11b. For example, as shown in Fig. 6, the light-emitting surface 11a of the light-emitting element 10, and if a translucent member 30 is included, the upper surface 30a of the translucent member 30 is attached to one side of a support plate 50, and the first electrode 12 of the light-emitting element 10 attached to the support plate 50 is brought into contact with the first light-reflecting portion 21s from the first light-reflecting portion 21s side and further pressed, thereby sinking the light-emitting element 10 into the light-reflecting member 20 as shown in Fig. 7. At this stage, both the first light reflecting portion 21s and the second light reflecting portion 22s maintain their plasticity. The electrode formation surface 11b of the light-emitting element 10 and a portion of the side surface 12c of the first electrode 12 of the light-emitting element 10 facing the electrode formation surface 11b are covered by the first light reflecting portion 21s. The second light reflecting portion 22s directly below and in the vicinity of the light-emitting element 10 is thin, while the second light reflecting portion 22s between adjacent light-emitting elements 10 is thick. That is, at least a portion of the boundary between the first light reflecting portion 21s and the second light reflecting portion 22s is inclined or curved toward the upper surface as it moves away from the first electrode 12. After the light-emitting element 10 is lowered into the light-reflecting member 20, the light-reflecting member 20 is heated and cured. The support plate 50 is removed before or after the light-reflecting member 20 is cured, as shown in FIG. 8 .

[0054] [Electrode Exposing Step] In the electrode exposing step, for example, the second light reflecting portion 22s is ground to expose the second surface 12b of the first electrode 12 from the second light reflecting portion 22s.

[0055] 9 , in the second electrode formation step, a second electrode 13 is formed that is bonded to the second surface 12b of the first electrode 12 and extends from the second surface 12b to the outer surface of the second light reflecting portion 22s. Since the second light reflecting portion 22s contains a small amount of the light reflecting material 211 that functions as an aggregate or does not contain the light reflecting material 211, by forming the second electrode 13 on the outer surface of the second light reflecting portion 22s, it is possible to improve the adhesion between the light reflecting member 20 and the second electrode 13 and suppress peeling of the second electrode 13.

[0056] After the second electrodes 13 are formed, the substrate is cut at predetermined cutting positions to separate the substrate into individual pieces. The light emitting device 1 is manufactured through the above steps.

[0057] In the light emitting device 1 of the embodiment described above, an example has been shown in which at least a part of the boundary between the first light reflecting portion 21 and the second light reflecting portion 22 is inclined toward the upper surface as it moves away from the first electrode 12. However, the light emitting device 1 according to the invention of the present disclosure is not limited to this, and as shown in Fig. 2, the boundary between the first light reflecting portion 21 and the second light reflecting portion 22 may be parallel to the mounting surface, for example.

[0058] In the examples, the light-emitting device 1 shown in Figure 1 was fabricated using a light-reflecting member 20 consisting of: (a) a first mixed material (1) prepared by mixing flake-shaped boron nitride (light-reflecting material), silica (supporting material), and titania (light-scattering material) in a weight ratio of 2.5:2.5:1 with an aqueous solution of potassium hydroxide (KOH) in a weight ratio of 6:2; and (b) a second mixed material (2) prepared by mixing spherical aluminum oxide (light-reflecting material), silica (supporting material), and titania (light-scattering material) in a weight ratio of 2:3.2:4 with an aqueous solution of potassium hydroxide (KOH) in a weight ratio of 9.2:2.3. Here, a light-emitting diode emitting light with a peak wavelength of 460 nm was used as the light-emitting element 10, and a translucent member formed by mixing and sintering a YAG phosphor and aluminum oxide was used. The second electrode 13 was formed on the surface of the second light reflecting portion 22 on the mounting surface side produced as described above. In contrast, as a reference example, a light reflective member 20 was formed using only the first light reflecting portion 21, and the second electrode 13 was formed on the surface of the first light reflecting portion 21 exposed on the mounting surface side, except for this, a light emitting device was produced in the same manner as in the example. The light emitting device of the example exhibited better adhesion than the light emitting device of the reference example.

[0059] It should be noted that the embodiments disclosed herein are illustrative in all respects and are not intended to be limiting.

[0060] The light-emitting device and the method for manufacturing the light-emitting device according to the present disclosure include the following aspects: [Item 1] A light-emitting device comprising: a light-emitting element including: a semiconductor structure having a light-emitting surface, an electrode-forming surface opposite the light-emitting surface, and a side surface located between the light-emitting surface and the electrode-forming surface; and an electrode provided on the electrode-forming surface; a light-reflecting member having a lower surface and covering the side surface of the semiconductor structure and the side surface of the electrode, wherein the electrode has an exposed surface that is not covered by the light-reflecting member, and the light-reflecting member covering the side surface of the semiconductor structure and comprising: a first light-reflecting portion covering the side surface of the semiconductor structure and comprising an inorganic material as a main material and a light-reflecting material having a refractive index higher than that of the inorganic material; and a second light-reflecting portion having the lower surface and covering at least a portion of the side surface of the electrode, comprising the inorganic material and containing the light-reflecting material in a content lower than that of the first light-reflecting portion or being substantially free of the light-reflecting material. [Item 2] The light-emitting device according to claim 1, further comprising: a light-transmitting member disposed on the light-emitting surface of the semiconductor structure, wherein the first light-reflecting portion further covers the side surface of the light-transmitting member. [Item 3] The light-emitting device according to item 1 or 2, wherein the first light reflecting portion further covers a portion of the side surface of the electrode. [Item 4] The light-emitting device according to any one of items 1 to 3, wherein at least a portion of the boundary between the first light reflecting portion and the second light reflecting portion is inclined or curved toward the upper surface as it moves away from the electrode. [Item 5] The light-emitting device according to any one of items 1 to 4, wherein the side surface of the light-reflecting member includes a first side surface of the first light reflecting portion and a second side surface of the second light reflecting portion located below the first side surface. [Item 6] The light-emitting device according to any one of items 1 to 5, wherein an auxiliary electrode is disposed on a lower surface of at least a portion of the light-reflecting member and on a lower surface of the electrode, and is electrically connected to the electrode. [Item 7] The light-emitting device according to any one of items 1 to 6, wherein the light-reflecting material includes at least one selected from boron nitride, silicon nitride, aluminum nitride, and aluminum oxide. [Item 8] The light-emitting device according to any one of items 1 to 7, wherein the light-reflecting material includes plate-like or needle-like particles. [Item 9] The light emitting device according to any one of items 1 to 8, wherein the first light reflecting portion and the second light reflecting portion contain an alkali metal.[Item 10] A method for manufacturing a light emitting device, comprising: a step of preparing a light emitting element including a semiconductor structure having a light emitting surface, an electrode forming surface opposite the light emitting surface, and a side surface located between the light emitting surface and the electrode forming surface, and an electrode provided on the electrode forming surface; a step of preparing a light reflective inorganic member having a first light reflecting portion made of an inorganic material containing a light reflector and having plasticity, and a second light reflecting portion made of an inorganic material containing a light reflector at a content lower than that of the first light reflecting portion or containing substantially no light reflecting material, and having plasticity, the second light reflecting portion being disposed below the first light reflecting portion; and a step of pressing the electrode forming surface of the light emitting element by contacting the electrode with the first light reflecting portion side of the light reflective inorganic member, and causing the side surface of the semiconductor structure and the electrode forming surface to sink so that they are covered by the first light reflecting portion. [Item 11] The method for manufacturing a light-emitting device according to Item 10, further comprising, after the step of sinking the light-emitting element, removing a portion of the light-reflecting inorganic material on which the light-emitting element has been sinking from the second light-reflecting portion side, thereby exposing the electrode from the second light-reflecting portion.

[0061] REFERENCE SIGNS LIST 1 Light emitting device 10 Light emitting element 11 Semiconductor structure 11a Light emitting surface 11b Electrode forming surface 11c Side surface 12 First electrode 12a First surface 12b Second surface 12c Side surface 13 Second electrode 20 Light reflecting member 21 First light reflecting portion 22 Second light reflecting portion 30 Light-transmitting member 50 Support plate

Claims

1. A light emitting element including a semiconductor structure having a light emitting surface, an electrode forming surface opposite to the light emitting surface, and a side surface located between the light emitting surface and the electrode forming surface, and an electrode provided on the electrode forming surface; and a light reflective member having a bottom surface and covering the side surface of the semiconductor structure and the side surface of the electrode, the electrode having an exposed surface that is not covered by the light reflective member, the light reflective member including: a first light reflective portion covering the side surface of the semiconductor structure and comprising an inorganic material that is a main material and a light reflective material having a refractive index higher than that of the inorganic material; and a second light reflective portion having the bottom surface and covering at least a portion of the side surface of the electrode, comprising the inorganic material, and containing a smaller amount of the light reflective material than the first light reflective portion or being substantially free of the light reflective material.

2. The light emitting device according to claim 1, further comprising a light-transmitting member disposed on the light emitting surface of the semiconductor structure, wherein the first light reflecting portion further covers a side surface of the light-transmitting member.

3. The light emitting device according to claim 1 or 2, wherein the first light reflecting portion further covers a part of a side surface of the electrode.

4. A light-emitting device described in any one of claims 1 to 3, wherein at least a portion of the boundary between the first light-reflecting portion and the second light-reflecting portion is inclined or curved toward the upper surface as it moves away from the electrode.

5. A light emitting device described in any one of claims 1 to 4, wherein the side surface of the light reflecting member includes a first side surface of the first light reflecting portion and a second side surface of the second light reflecting portion located below the first side surface.

6. The light emitting device according to any one of claims 1 to 5, further comprising an auxiliary electrode disposed on the underside of at least a portion of said light reflecting member and on the underside of said electrode, said auxiliary electrode being electrically connected to said electrode.

7. The light emitting device according to any one of claims 1 to 6, wherein the light reflecting material contains at least one material selected from the group consisting of boron nitride, silicon nitride, aluminum nitride, and aluminum oxide.

8. The light emitting device according to any one of claims 1 to 7, wherein the light reflecting material contains plate-like or needle-like particles.

9. The light emitting device according to any one of claims 1 to 8, wherein the first light reflecting portion and the second light reflecting portion contain an alkali metal.

10. A method for manufacturing a light-emitting device, comprising: a step of preparing a light-emitting element including a semiconductor structure having a light-emitting surface, an electrode-forming surface opposite to the light-emitting surface, and a side surface located between the light-emitting surface and the electrode-forming surface, and an electrode provided on the electrode-forming surface; a step of preparing a light-reflecting inorganic member having a first light-reflecting portion made of an inorganic material containing a light-reflecting material and having plasticity, and a second light-reflecting portion made of an inorganic material containing a light-reflecting material in a content less than that of the first light-reflecting portion or containing substantially no light-reflecting material, and having plasticity, the second light-reflecting portion being disposed below the first light-reflecting portion; and a step of pressing the electrode-forming surface of the light-emitting element by contacting the electrode with the first light-reflecting portion side of the light-reflecting inorganic member, thereby causing the side surface and the electrode-forming surface of the semiconductor structure to be covered by the first light-reflecting portion.

11. A method for manufacturing a light-emitting device as described in claim 10, further comprising, after the step of sinking the light-emitting element, a step of removing a portion of the light-reflecting inorganic material in which the light-emitting element has been sinked from the second light-reflecting portion side to expose the electrode from the second light-reflecting portion.

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