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

Abstract

To provide a light-emitting device having excellent light extraction efficiency for ultraviolet light.SOLUTION: A light-emitting device comprises: a substrate which has a recess defined by a wall portion and a bottom portion; a light-emitting element which is disposed on the bottom portion, and includes a semiconductor laminate having an upper surface, a lower surface on the opposite side to the upper surface, and a side surface between the upper surface and the lower surface, and an electrode disposed on the lower surface of the semiconductor laminate; a reflective member which covers an inner surface of the wall portion; and a translucent member which is disposed on an upper surface of the wall portion. The reflective member includes: a first reflective member which is in contact with the inner surface and has an inclined surface on a side facing the side surface of the light-emitting element; and a second reflective member which covers the inclined surface of the first reflective member, has a higher reflectance than the first reflective member, and has a thickness at a position lower than the lower surface of the semiconductor laminate of the light-emitting element greater than a thickness at a position higher than the upper surface of the light-emitting element.SELECTED DRAWING: Figure 1B

Description

Technical Field

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

Background Art

[0002] As a light-emitting device such as a light-emitting diode (LED) that emits ultraviolet light, a light-emitting device including a light-reflecting member with high light resistance and a method for manufacturing the light-emitting device are known (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Further improvement in the light extraction efficiency of ultraviolet light is required.

Means for Solving the Problems

[0005] The present disclosure includes the following configurations. A substrate including a recess defined by a wall portion and a bottom portion, A light-emitting element disposed on the bottom portion, the light-emitting element including a semiconductor laminate including an upper surface, a lower surface opposite to the upper surface, and a side surface between the upper surface and the lower surface, and an electrode disposed on the lower surface of the semiconductor laminate, A reflecting member covering the inner surface of the wall portion, A light-transmitting member disposed on the upper surface of the wall portion, and the reflecting member includes a first reflecting member that is in contact with the inner surface and has an inclined surface on a side facing the side surface of the light-emitting element, A light-emitting device including a second reflecting member that covers the inclined surface of the first reflecting member and has a higher reflectivity than the first reflecting member, wherein the thickness of the second reflecting member at a position lower than the lower surface of the stacked structure of the light-emitting elements is thicker than the thickness at a position higher than the upper surface of the light-emitting elements.

Advantages of the Invention

[0006] As described above, a light-emitting device excellent in light extraction efficiency of ultraviolet light can be obtained.

Brief Description of the Drawings

[0007]

Figure 1A

Figure 1B

Figure 2A

Figure 2B

Figure 3

Embodiments for Carrying Out the Invention

[0008] Embodiments for carrying out the present invention will be described below with reference to the drawings. However, the embodiments shown below are examples of a light-emitting device and a method of manufacturing the light-emitting device for embodying the technical idea of the present invention, and the present invention is not limited to the light-emitting device and the method of manufacturing the light-emitting device as described below.

[0009] Also, this specification does not identify the members shown in the claims with the members in the embodiments. In particular, dimensions, materials, shapes, relative arrangements, etc. of the components described in the embodiments are not intended to limit the scope of the present disclosure only to those, unless specifically stated. Note that the sizes and positional relationships of the members shown in each drawing may be exaggerated for clarity of explanation. Further, in the following description, the same names and reference numerals indicate the same or equivalent members, and detailed descriptions are omitted as appropriate. Also, terms indicating specific directions and positions (e.g., "upper", "lower", "right", "left", and other terms including these terms) are used as necessary. The use of these terms is for facilitating the understanding of the invention with reference to the drawings, and the technical scope of the present invention is not limited by the meanings of these terms. A plan view means viewing directly or through a perspective from the upper or lower surface. In some cases, an end view showing only the cut surface is used as a cross-sectional view. Also, portions with the same reference numerals appearing in a plurality of drawings indicate the same portions or members.

[0010] The light-emitting device 100 according to the embodiment includes a substrate 10, a light-emitting element 20, a reflecting member 30, and a light-transmissive member 40. The substrate 10 includes an insulating base material 11 and a conductive member 12 serving as a pair of positive and negative electrodes. The substrate 10 includes a recess 10R defined by a wall portion 10W and a bottom portion 10B. Specifically, the recess 10R is a space defined by the inner surface 10M of the wall portion 10W and the upper surface 10U of the bottom portion 10B. The upper surface 10T of the wall portion 10 is at a position higher (above) than the upper surface 20U of the light-emitting element 20. In other words, the wall portion 10W is higher in height than the light-emitting element 20.

[0011] The light-emitting element 20 is disposed on the bottom portion 10B of the substrate 10. Specifically, the light-emitting element 20 is disposed on the upper surface 10U of the bottom portion 10B via a bonding member (not shown). The light-emitting element 20 is disposed away from the inner surface 10M of the wall portion 10W of the substrate 10. The reflecting member 30 is disposed in contact with the inner surface 10M of the wall portion 10W and the upper surface 10U of the bottom portion 10B. The upper end of the reflecting member 30 is at a position higher than the upper surface 20U of the light-emitting element 20.

[0012] The reflecting member 30 includes a first reflecting member 31 and a second reflecting member 32 having a higher reflectivity than the first reflecting member 31. The first reflecting member 31 is in contact with the inner surface 10M of the wall portion 10W and the upper surface 10U of the bottom portion 10B of the base body 10. The first reflecting member 31 includes an inclined surface 31a on the side facing the side surface 20S of the light emitting element 20. The upper end of the inclined surface 31a is at a position higher than the upper surface 20U of the light emitting element 20. The height of the first reflecting member 31 from the upper surface 10U of the bottom portion 10 is low on the side closer to the light emitting element 20 and high on the side closer to the wall portion 10W. In other words, the thickness of the first reflecting member 31 from the inner surface 10M of the wall portion 10W is thick on the side closer to the upper surface 10U of the bottom portion 10 and thin on the side closer to the upper surface 10T of the wall portion 10W. Note that the thickness in the direction perpendicular to the upper surface 10U of the bottom portion 10B, that is, the vertical direction, is referred to as the "height" and is described separately from the thickness in the horizontal direction, that is, the left-right direction, of the upper surface 10U of the bottom portion 10B.

[0013] The second reflecting member 32 covers the inclined surface 31a of the first reflecting member 31. Similar to the first reflecting member 31, the second reflecting member 32 is thicker at a position higher than the upper surface 20U of the light emitting element 20 on the side closer to the bottom portion 10B of the base body 10, that is, at a position below the lower surface of the semiconductor laminate 21 of the light emitting element 20. And the second reflecting member 32 is thicker than the first reflecting member 31 at a position higher than the upper surface 20U of the light emitting element 20.

[0014] The semiconductor laminate 21 of the light emitting element 20 includes an electrode 22 on its lower surface. Specifically, the semiconductor laminate 21 includes an element substrate such as sapphire and a semiconductor layer located below the element substrate, and the electrode 22 is joined to the semiconductor layer. The semiconductor layer includes an n-type semiconductor layer, a light emitting layer, and a p-type semiconductor layer from the element substrate side. That is, a light emitting layer is provided on the side closer to the lower surface of the semiconductor laminate 21. Thereby, light from the light emitting layer is strongly emitted from the lower surface of the semiconductor laminate 21 and from the side surface closer to the lower surface. Therefore, by increasing the thickness of the second reflecting member 32 located below the lower surface of the semiconductor laminate 21, light can be efficiently reflected.

[0015] The light from the light-emitting element 20 is mainly emitted from the upper surface 20U and the side surface 20S of the light-emitting element 20. The light emitted from the light-emitting element 20 is reflected by the reflecting member 30. By making the surface that reflects the light from the light-emitting element 20, that is, the reflecting surface, an inclined surface, that is, a surface facing obliquely upward, it is possible to easily reflect the light emitted from the light-emitting element 20 upward. When the reflecting surface of the reflecting member 30 is an inclined surface, the thickness from the inner surface 10M of the wall portion 10W becomes thinner toward the upper side, that is, the higher position. Therefore, light is more likely to escape at higher positions. In the present embodiment, a second reflecting member 32 having a higher reflectivity than the first reflecting member 31 is disposed on the inclined surface 31a of the first reflecting member 31, and the portion where the thickness of the first reflecting member 31 becomes thinner, that is, at a position higher than the upper surface 20U of the light-emitting element 20, the thickness of the second reflecting member 32 is made thicker than the thickness of the first reflecting member 31. Thereby, it is possible to reduce the light from escaping from the reflecting member 30 at a position close to the upper surface 10T of the wall portion 10W and improve the light extraction efficiency.

[0016] The first reflecting member 31 is configured to include light-reflective particles and a base material. By including light-reflective particles having an aspect ratio of 10 or more as the light-reflective particles, the inclined surface 31a of the first reflecting member 31 can be made a surface with irregularities as shown in FIG. 1B. This is because the light-reflective particles having an aspect ratio of 10 or more are mixed in the base material in various directions, resulting in high thixotropy and making it difficult to form a flat inclined surface. In particular, in the vicinity of the upper end of the first reflecting member 31, it is difficult to arrange light-reflective particles having an aspect ratio of 10 or more, and as a result, the ratio of the base material tends to be high, and the overall thickness tends to be thin. Further, since the second reflecting member 32 before curing is hardly fluid, it is difficult to flow downward along the inclined surface 31a. Therefore, it is relatively easy to stay also at the upper end of the inclined surface 31a. Thereby, the thickness of the second reflecting member 32 can be made thicker in the vicinity of the upper end where the thickness of the first reflecting member 31 tends to be thin.

[0017] In addition, the second reflecting member 32, which has a higher reflectance than the first reflecting member 31, is substantially occupied by light-reflective particles as a constituent member, and maintains its shape by heating and curing. When the thickness of such a second reflecting member 32 becomes 150 μm or more, cracks are likely to occur. Therefore, by using the first reflecting member 31 having the inclined surface 31a as a base and disposing the second reflecting member 32 with a relatively small thickness on the inclined surface 31a, the second reflecting member 32 having a high reflectance can be formed as an inclined surface, and further, the occurrence of cracks can be reduced.

[0018] Hereinafter, each member will be described in detail.

[0019] (Substrate) The substrate 10 includes a recess 10R defined by a wall portion 10W and a bottom portion 10B. Specifically, the recess 10R is a space defined by the inner surface 10M of the wall portion 10 and the upper surface 10U of the bottom portion 10B. The wall portion 10W and the bottom portion 10B may be integral, or a separate wall portion 10W may be disposed on the bottom portion 10B. The light-emitting element 20 is joined onto the upper surface 10U of the bottom portion 10B via an adhesive member (not shown). The upper surface 10T of the wall portion 10W is at a position higher than the upper surface 20U of the light-emitting element 20. In other words, the height of the wall portion 10W from the upper surface 10U of the bottom portion 10B is greater than the height of the light-emitting element 20. For example, the height of the wall portion 10W from the upper surface 10U of the bottom portion 10B can be set to be 1.1 times or more and 2.5 times or less the height of the light-emitting element 20.

[0020] The substrate 10 includes an insulating base material 11 serving as a base material and a conductive member 12 serving as an electrode. In the example shown in FIG. 1B, a metal film 61 (60) is disposed on the upper surface 10T of the wall portion 10W. The first metal film 61 is a member for facilitating the joining of a joining member 50 for joining the translucent member 40 described later and the wall portion 10W. Depending on the material of the joining member 50, the first metal film 61 can be omitted.

[0021] As the base material 11, for example, ceramics such as aluminum nitride, silicon nitride, and aluminum oxide can be used. As the conductive member 12, for example, metals such as copper, aluminum, gold, and silver can be used. The thickness of the conductive member 12 can be, for example, 5 μm to 17 μm. Further, the conductive member 12 is disposed not only on the upper surface 10U of the bottom portion 10B but also on the lower surface 10F of the bottom portion 10B. The conductive member 12 disposed on the upper surface 10U of the bottom portion 10B and the conductive member 12 disposed on the lower surface 10F can be electrically connected by a conductive member disposed on the outer surface 10S of the base 10 or a via penetrating the bottom portion 10B.

[0022] (Light-emitting element) The light-emitting device 100 includes at least one light-emitting element 20. The light-emitting element 20 is a light-emitting element capable of emitting ultraviolet light. The ultraviolet light refers to light having a wavelength with a peak emission wavelength of 200 to 410 nm, for example. The number of ultraviolet light-emitting elements used in one light-emitting device is one or two or more. When a plurality are used, for example, they may be ultraviolet light-emitting elements having the same peak emission wavelength, or may be ultraviolet light-emitting elements having different peak emission wavelengths. As the light-emitting element 20, for example, a semiconductor light-emitting element such as a light-emitting diode can be used. The light-emitting element 20 includes a semiconductor laminate 21 and a pair of positive and negative electrodes 22. The semiconductor laminate 21 includes, for example, an element substrate such as sapphire and a semiconductor layer formed thereon. The planar shape of the light-emitting element 20 can be a polygon such as a triangle, a quadrilateral, or a hexagon. The size of the light-emitting element 20 can be, for example, 100 μm or more and 3000 μm or less on one side in a plan view. The height of the light-emitting element 20 (the sum of the height of the semiconductor laminate 21 and the height of the electrode 22) can be, for example, 100 μm or more and 3100 μm or less. Specifically, it can be a square with one side being about 600 μm, about 1400 μm, about 1700 μm, etc. Further, the light-emitting element 20 may be a rectangle having a long side and a short side in a plan view. For example, it can have a size of 1100 μm × 200 μm.

[0023] The semiconductor laminate 21 includes an n-type semiconductor layer, a p-type semiconductor layer, and a light-emitting layer sandwiched therebetween. Such a semiconductor laminate including a light-emitting layer may contain, for example, In x Al y Ga 1-x-y N (0 ≦ x, 0 ≦ y, x + y ≦ 1).

[0024] The semiconductor laminate 21 may have a structure including one or more light-emitting layers between the n-type semiconductor layer and the p-type semiconductor layer, or may have a structure in which a structure including an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer in this order is repeated a plurality of times. When the semiconductor laminate 21 includes a plurality of light-emitting layers, it may include light-emitting layers having different emission peak wavelengths, or may include light-emitting layers having the same emission peak wavelength. Note that the same emission peak wavelength includes cases where there is a variation of about several nm. The combination of emission peak wavelengths between the plurality of light-emitting layers can be appropriately selected. For example, when the semiconductor laminate includes two light-emitting layers, a combination of a light-emitting layer having an emission peak wavelength of 365 nm and a light-emitting layer having an emission peak wavelength of 405 nm can be selected.

[0025] The light-emitting element 20 includes a pair of positive and negative electrodes 22 on the lower surface or the upper surface of the semiconductor laminate 21. As the electrode 22, an electrically conductive material can be used, and for example, it can be made of gold, silver, tin, platinum, rhodium, titanium, aluminum, tungsten, palladium, nickel, or an alloy thereof. The electrode 22 can include an ohmic electrode in contact with the lower surface or the upper surface of the semiconductor laminate 21, and a pad electrode connected to the ohmic electrode and connected to the outside. The thickness of the electrode 22 can be, for example, 10 μm or more and 50 μm or less. When the electrode 22 is provided on the lower surface of the light-emitting element 20, it is fixed to the substrate 10 by a conductive adhesive member such as solder, bumps, or a metal paste and is electrically connected. When the electrode 22 is provided on the upper surface of the light-emitting element 20, it is fixed to the substrate 10 by an insulating adhesive member such as an epoxy resin and is electrically connected to the conductive member 12 of the substrate 10 by a wire containing Au, Ag, etc. When the electrode 22 is provided on both the upper and lower surfaces of the light-emitting element 20, it is fixed to and electrically connected to the substrate 10 by a conductive adhesive member, and is also electrically connected using a wire.

[0026] In addition to the light-emitting element 20, the light-emitting device 100 may include a protection element. Examples of the protection element include a Zener diode and a varistor. Preferably, the whole or a part of the protection element is embedded in the reflection member 30.

[0027] (Reflection member) The reflection member 30 is a member for reflecting the light emitted from the light-emitting element 20. The reflection member 30 is composed of a first reflection member 31 and a second reflection member 32. The reflectance of the second reflection member 32 with respect to the peak wavelength of the light from the light-emitting element 20 is higher than the reflectance of the first reflection member 31.

[0028] The first reflection member 31 is composed of, for example, light-reflective particles and a base material. The light-reflective particles are particles having light reflectivity with respect to the light emitted from the light-emitting element 20. The reflectance of the first reflection member 31 with respect to the emission peak wavelength emitted from the light-emitting element 20 is 50% or more and 90% or less. The light-reflective particles include boron nitride. The average particle size of boron nitride can be 0.6 μm or more and 43 μm or less. Further, the average aspect ratio of boron nitride is preferably 10 or more. In addition to boron nitride, the light-reflective particles may include titanium oxide, zirconium oxide, boron nitride, aluminum oxide, etc. For example, in the first reflection member 31, the weight ratio of silicon oxide to boron nitride can be, for example, 1:0.5 to 1:5.

[0029] The particle size of the light-reflective particles can be calculated using a scanning electron microscope "TM3030Plus" manufactured by Hitachi High-Technologies Corporation. First, one side of a carbon double-sided tape is attached to the sample stage of the microscope, and then the light-reflective particles are placed on the other side of the double-sided tape. The pixel number of the microscope is set to 1.23 million pixels, the magnification is set from 1000 times to 2000 times, and images of 100 light-reflective particles are acquired. Then, the particle size of each light-reflective particle is measured using image analysis software. Next, the median diameter of the measured particles is calculated, and this calculated value is taken as the average particle size of the light-reflective particles. Also, the particle size of the light-reflective particles may be measured and calculated by extracting the cross-section of the first reflecting member 31 of the light-emitting device 100 by SEM and using image analysis software.

[0030] The base material may be composed of an organic material, an inorganic material, or both an organic material and an inorganic material. As the organic material, a resin can be used. As the inorganic material, an alkali metal silicate can be used.

[0031] The first reflecting member 31 is composed of, for example, a mixture containing boron nitride and an alkali metal silicate. This mixture can be produced by mixing a mixed powder of boron nitride powder and silicon oxide powder with an alkali solution (for example, potassium hydroxide), and then heat-curing. When the alkali solution is potassium hydroxide, upon heat-curing, silicon oxide reacts with potassium hydroxide to produce potassium silicate, which is an alkali metal silicate. Boron nitride is a member capable of reducing the shrinkage of the mixture during heat-curing. Note that aluminum oxide can be used instead of boron nitride.

[0032] The first reflecting member 31 can be arranged in contact with 50% or more of the inner surface 10M of the wall portion 10W. In the example shown in FIG. 1B, the first reflecting member 31 covers from the upper end to the lower end of the inner surface 10M, that is, covers all of the inner surface 10M. The inclined surface 31a of the first reflecting member 31 is preferably inclined at 30 degrees or more and 80 degrees or less with respect to the upper surface 10U of the bottom portion 10B. When the inclined surface 31a of the first reflecting member 31 has irregularities in a cross-sectional view as shown in FIG. 1B, a virtual straight line connecting the upper end and the lower end of the inclined surface 31a is pseudo-considered as the inclined surface 31a, and the angle formed by this pseudo-inclined surface 31a and the upper surface 10U of the bottom portion 10B is defined as the angle of the inclined surface 31a.

[0033] The reflectivity of the second reflecting member 32 with respect to the emission peak wavelength emitted from the light-emitting element 20 can be 80% or more and 99% or less. The second reflecting member 32 contains zirconium oxide and a base material. Examples of the base material include pure water, sodium silicate, potassium silicate, etc. The weight ratio of zirconium oxide to pure water can be 1:0.2 to 1:4. Or, the second reflecting member 32 can be made of only zirconium oxide. The second reflecting member 32 can be formed, for example, by heating and curing the first reflecting member 31, arranging an aqueous solution in which zirconium oxide powder is mixed in pure water on the inclined surface 31a of the first reflecting member 31, and heating. The thickness of the second reflecting member 32 (the thickness in the direction parallel to the upper surface 10U of the bottom portion 10B) can be 20 μm or more and 200 μm or less at the portion facing the side surface 20S of the light-emitting element 20, and can be 10 μm or more and 100 μm or less at the portion located above the upper surface 20U of the light-emitting element 20.

[0034] (Light-transmitting member) The light-transmitting member 40 is a member that serves as the light extraction surface of the light-emitting device 100, and is joined onto the upper surface 10T of the wall portion 10W of the base 10 via a joining member 50. The light-transmitting member 40 has the property of transmitting light from the light-emitting element. Here, the light-transmittance means transmitting 70% or more of the light from the light-emitting element 20.

[0035] The upper surface of the light-transmitting member 40 can be a flat surface, a curved surface, or a surface that is a combination of these. For example, by making the upper surface of the light-transmitting member 40 a hemispherical surface, it can function as a convex lens. The light-transmitting member 40 can be made of, for example, glass, sapphire, etc.

[0036] (metal film) The metal film 60 can be disposed in a portion where the bonding member 50 comes into contact. That is, the metal film 60 (first metal film 61) is disposed on the upper surface 10T of the wall portion 10W of the base 10, and the metal film 60 (second metal film 62) is disposed on the lower surface of the light-transmitting member 40 facing the upper surface 10T. When the light-emitting element 20 is hermetically sealed, the metal film 60 is disposed around the entire periphery of the upper surface 10T of the wall portion 10W and the entire periphery of the outer periphery of the lower surface of the light-transmitting member 40. When the light-emitting element 20 is not hermetically sealed, the metal film 60 is disposed on a portion of the upper surface 10T of the wall portion 10W and on a portion of the outer periphery of the lower surface of the light-transmitting member 40 facing that portion.

[0037] (jointing material) The bonding member 50 is a member that bonds the base body 10 and the light-transmitting member 40. When the base body 10 and the light-transmitting member 40 include a metal film 60, the bonding member 50 bonds the base body 10 and the light-transmitting member 40 via the metal film 60.

[0038] Examples of the bonding member 50 include tin-bismuth, tin-copper, tin-silver, and gold-tin solders, eutectic alloys such as alloys mainly composed of Au and Sn, Au and Si, Au and Ge, Au and Cu, and Ag and Cu, conductive pastes such as silver, gold, and palladium, anisotropic conductive materials, and brazing filler metals of low melting points. In particular, it is preferable to use solder, eutectic alloys such as alloys, and bumps that are resistant to deterioration by ultraviolet light.

[0039] The thickness of the bonding member 50 can be, for example, about 5 μm to 50 μm.

[0040] Examples of the metal film 60 include single materials such as gold (Au), silver (Ag), copper (Cu), nickel (Ni), titanium (Ti), chromium (Gr), tin (Sn), aluminum (Al), palladium (Pd), platinum (Pt), rhodium (Rh), tungsten (W), molybdenum (Mo), and iron (Fe), as well as composite materials thereof. The thickness of the metal film 60 can be, for example, 5 μm to 17 μm. The metal film 60 can be formed by plating, sputtering, or other known methods. Furthermore, when the metal film 60 is made of the same material as the conductive member 12, the two can be formed simultaneously. [Example]

[0041] (Example) 2A and 2B show SEM photographs of the light-emitting device of the present disclosure. Note that these SEM photographs were taken before the light-transmitting member was placed. In other words, they are SEM photographs showing the state in which the light-emitting element and the reflective member are placed on the base.

[0042] A substrate was prepared, comprising an aluminum nitride substrate and a conductive member with Au as the outermost surface. The outer dimensions of the substrate were 3.5 mm long x 3.5 mm wide and 1 mm high. At this stage, the substrate may be an aggregate substrate containing portions that will become multiple light-emitting devices. In this case, a final cutting process is required to separate the substrate into individual pieces. The recess in the substrate has a rectangular opening. The thickness of the bottom is 0.1 mm, and the height of the wall from the top surface of the bottom is 0.9 mm.

[0043] A gallium nitride light-emitting element was prepared as the light-emitting element. The light-emitting element had dimensions of 1 mm length x 1 mm width and 0.7 mm thickness. The light-emitting element had an emission peak wavelength of 365 nm.

[0044] Au-Sn solder was placed on a pair of conductive members placed on the upper surface of the bottom of the base, and the electrodes of the light-emitting element were placed on top of it so that they faced each other, and then the solder was hardened by heating.

[0045] The first reflective member was prepared. The first reflective member was prepared by mixing a powder of light-reflective particles having an average particle size of 1 μm and an aspect ratio of 4.6, and a powder of silicon oxide having a median diameter of 0.4 μm to obtain a mixed powder. Boron nitride was used as the light-reflective particles. Silicon oxide and boron nitride were mixed at a weight ratio of 4:5.

[0046] The mixed powder and an alkaline solution with a concentration of 3 mol / L were then mixed to prepare a mixture. Potassium hydroxide was used as the alkaline solution. The alkaline solution and the mixed powder were mixed at a weight ratio of 5.8:9.

[0047] The mixed solution was placed using a dispenser so as to be in contact with the inner surface of the wall portion of the substrate. Then, it was heated at a heating temperature of 90 °C and a pressure of 1 MPa for 1 hour. Next, by heating at a heating temperature of 200 °C and a pressure of 1 MPa for 2 hours, a first reflective member having an inclined surface was formed.

[0048] The second reflective member was prepared. The second reflective member used a powder of zirconium oxide having an average particle size of 20 μm as the light-reflective particles. An aqueous solution of zirconium oxide powder and pure water was prepared. The aqueous solution was placed on the inclined surface of the first reflective member using a dispenser. Zirconium oxide and pure water were mixed at a weight ratio of 1:1. Then, by heating at a heating temperature of 200 °C and a pressure of 1 MPa for 1 hour, the second reflective member was formed.

[0049] (Comparative Example 1) As Comparative Example 1, the same first reflective member as in the example was used, and the second reflective member was not provided. That is, it was carried out in the same manner as in the example except that only the first reflective member was used as the reflective member.

[0050] (Comparative Example 2) As Comparative Example 2, it was carried out in the same manner as in the example except that titanium oxide was used instead of zirconium oxide as the light-reflective particles used for the second reflective member of the example.

[0051] FIG. 3 is a graph showing the reflectance of the examples and comparative examples. As shown in the graph, the reflectance of the light-emitting device according to the example was higher than that of the comparative example for light with a wavelength shorter than 400 nm. The spectral reflectance was measured using a standard white plate manufactured by the Japan Color Research Institute and a spectrometer (model number V-550) manufactured by JASCO Corporation.

[0052] Aspects of the present invention are, for example, as follows.

[0053] [Item 1] A substrate including a recess defined by a wall portion and a bottom portion, A light-emitting element disposed on the bottom portion, the light-emitting element including a semiconductor laminate including an upper surface, a lower surface opposite to the upper surface, and a side surface between the upper surface and the lower surface, and an electrode disposed on the lower surface of the semiconductor laminate, A reflecting member covering the inner surface of the wall portion, A light-transmitting member disposed on the upper surface of the wall portion, Comprising, The reflecting member is in contact with the inner surface and includes a first reflecting member having an inclined surface on a side facing the side surface of the light-emitting element, A second reflecting member that covers the inclined surface of the first reflecting member and has a higher reflectance than the first reflecting member, and the thickness of the second reflecting member at a position lower than the lower surface of the semiconductor laminate of the light-emitting element is thicker than the thickness at a position higher than the upper surface of the light-emitting element. [Item 2] The light-emitting device according to Item 1, wherein the second reflecting member is thicker than the first reflecting member at a position higher than the upper surface of the light-emitting element. [Item 3] The light-emitting device according to Item 1 or Item 2, wherein the second reflecting member contains zirconium oxide. [Item 4] The light-emitting device according to any one of Items 1 to 3, wherein the first reflecting member contains boron nitride.

Explanation of reference numerals

[0054] 100... Light-emitting device 10… Substrate (10R… recess, 10W… wall portion, 10T… upper surface of the wall portion, 10M… inner surface of the wall portion, 10S… outer surface of the wall portion, 10B… bottom portion, 10U… upper surface of the bottom portion (bottom surface of the recess), 10F… lower surface of the bottom portion) 11… Base material 12… Conductive member 20… Light-emitting element (21… semiconductor laminate, 22… electrode, 20U… upper surface, 20S… side surface) 30… Reflective member (31… first reflective member, 31a… inclined surface, 32… second reflective member) 40… Translucent member 50… Bonding member 60… Metal film (61… first metal film, 62… second metal film)

Claims

1. A substrate having a recess defined by a wall portion and a bottom portion, a light-emitting element disposed on the bottom portion, the light-emitting element comprising a semiconductor laminate having an upper surface, a lower surface opposite to the upper surface, and a side surface between the upper surface and the lower surface, and an electrode disposed on the lower surface of the semiconductor laminate, a reflecting member covering the inner surface of the wall portion, a light-transmissive member disposed on the upper surface of the wall portion, and comprising, the reflecting member is in contact with the inner surface and has a first reflecting member having an inclined surface on a side facing the side surface of the light-emitting element, a second reflecting member covering the inclined surface of the first reflecting member and having a higher reflectivity than the first reflecting member, wherein the thickness of the second reflecting member at a position lower than the lower surface of the laminate structure of the light-emitting element is thicker than the thickness at a position higher than the upper surface of the light-emitting element, a light-emitting device.

2. The light-emitting device according to claim 1, wherein the second reflecting member is thicker than the first reflecting member at a position higher than the upper surface of the light-emitting element.

3. The light-emitting device according to claim 1, wherein the second reflecting member contains zirconium oxide.

4. The light-emitting device according to claim 1, wherein the first reflecting member contains boron nitride.

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