Light-emitting device

Abstract

To provide a light-emitting device which is excellent in light extraction efficiency of ultraviolet light.SOLUTION: A light-emitting device 100 includes: a light-emitting element 20 which includes a substrate 10 having a recess 10R regulated by a wall part 10W and a bottom part 10B, an upper face 20U, a lower face opposite to the upper face, and a side face 20S between the upper face and the lower face, and is arranged on the bottom part so that the bottom part and the lower face face each other, in which the light-emitting peak wavelength is 100 nm or more and 280 nm or less; a fluorine-based resin 70 coating the side face of the light-emitting element; and a light reflection member 30 which comes in contact with an inside face 10M of the wall part and the fluorine-based resin, and containing boron nitride, at a position far from the light-emitting element, where the light reflection member is exposed from the fluorine-based resin, at a position higher than the upper face of the light-emitting element.SELECTED DRAWING: Figure 1B

Description

[Technical Field]

[0001] The present disclosure relates to a light emitting device. [Background technology]

[0002] BACKGROUND ART As light emitting devices such as light emitting diodes (LEDs) that emit ultraviolet light, light emitting devices that include a light reflective member with high light resistance and methods for manufacturing such light emitting devices are known (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-50105 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for further improvement in the light extraction efficiency of ultraviolet light. [Means for solving the problem]

[0005] The light emitting device according to the embodiment includes the following configuration. a base having a recess defined by a wall and a bottom; a light-emitting element having an upper surface, a lower surface opposite to the upper surface, and a side surface between the upper surface and the lower surface, the light-emitting element being disposed on the bottom so that the bottom and the lower surface face each other, the light-emitting element having an emission peak wavelength of 100 nm or more and 280 nm or less; a fluorine-based resin that covers the side surface of the light-emitting element; a light reflecting member containing boron nitride, the light reflecting member being in contact with the inner surface of the wall portion and the fluorine-based resin at a position away from the light emitting element; Equipped with The light emitting device, wherein the light reflecting member is exposed from the fluorine-based resin at a position higher than the upper surface of the light emitting element. [Effects of the Invention]

[0006] According to the embodiment of the present disclosure, it is possible to provide a light emitting device with improved ultraviolet light extraction efficiency. [Brief explanation of the drawings]

[0007] [Figure 1A] 1 is a schematic top view of a light emitting device according to an embodiment of the present disclosure. [Figure 1B] FIG. 1B is a schematic cross-sectional view taken along line IB-IB shown in FIG. 1A. [Figure 2] FIG. 10 is a schematic cross-sectional view of a light emitting device according to Modification 1 of the present disclosure. [Figure 3] FIG. 10 is a schematic cross-sectional view of a light emitting device according to Modification 2 of the present disclosure. [Figure 4] FIG. 10 is a schematic cross-sectional view of a light emitting device according to Modification 3 of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, terms indicating specific directions or positions (for example, "upper," "lower," "right," "left," and other terms including these terms) will be used as necessary. The use of these terms is intended to facilitate understanding of the invention with reference to the drawings, and the meaning of these terms does not limit the technical scope of the present invention. Furthermore, a plan view refers to a view directly or through-view from the top or bottom. Furthermore, parts that appear with the same reference numerals in multiple drawings indicate the same parts or members.

[0009] As shown in FIGS. 1A and 1B, a light-emitting device 100 according to the embodiment includes a base 10, a light-emitting element 20, a light-reflecting member 30, and a fluorine-based resin 70. The base 10 includes an insulating substrate 11 and conductive members 12 that serve as a pair of positive and negative electrodes. The base 10 includes a recess 10R defined by a wall 10W and a bottom 10B. Specifically, the recess 10R is a space defined by an inner surface 10M of the wall 10W and an upper surface 10U of the bottom 10B. The upper surface 10U of the bottom 10B is also referred to as the bottom surface defining the recess 10R. The upper surface 10T of the wall 10W is located higher (above) than the upper surface 20U of the light-emitting element 20. In other words, the wall 10W is taller than the light-emitting element 20.

[0010] The light-emitting element 20 is disposed on the bottom 10B of the base 10. Specifically, the light-emitting element 20 is disposed on the upper surface 10U of the bottom 10B via an adhesive member (not shown). The light-emitting element 20 is disposed away from the inner surface 10M of the wall 10W of the base 10. The light-emitting element 20 has an emission peak wavelength of 100 nm or more and 280 nm or less. The light-reflecting member 30 is made of plate-like particles containing boron nitride and has excellent light resistance. The light-reflecting member 30 is disposed in contact with the inner surface 10M of the wall 10W and the upper surface 10U of the bottom 10B. As shown in FIG. 2, the upper end of the light-reflecting member 30 is located higher than the upper surface 20U of the light-emitting element 20. The fluororesin 70 covers the side surface 20S of the light-emitting element 20 and is disposed in contact with the light-reflecting member 30.

[0011] The light reflecting member 30 is in contact with the inner side surface 10M of the wall portion 10W and the upper surface 10U of the bottom portion 10B, and is arranged spaced apart from the light emitting element 20. The fluororesin 70 is in contact with and covers the side surface 20S of the light emitting element 20. The fluororesin 70 is arranged in contact with the light reflecting member 30. The upper end of the light reflecting member 30 is located higher than the upper surface 20U of the light emitting element 20. The light reflecting member 30 is located higher than the upper surface of the light emitting element 20, and at least a portion of the light reflecting member 30 is exposed from the fluororesin 70. In other words, the upper end of the light reflecting member 30 is exposed from the fluororesin 70. The fluororesin 70 may also be arranged spaced apart from the upper surface 10U of the bottom portion 10B (the bottom surface that defines the recess 10).

[0012] In the example shown in FIG. 2 , 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, with the electrode 22 bonded to the semiconductor layer. The semiconductor layer includes, from the element substrate side, an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer. That is, the light-emitting layer is located closer to the lower surface of the semiconductor laminate 21. As a result, light from the light-emitting layer is strongly emitted from the side surface closer to the lower surface of the semiconductor laminate 21. By covering the side surface closer to the lower surface of the semiconductor laminate 21 with a fluorine-based resin 70, the light reflecting member 30 can be disposed near the side surface closer to the lower surface of the semiconductor laminate 21 without contacting the side surface closer to the lower surface of the semiconductor laminate 21. As a result, reflection of light emitted from the semiconductor laminate 21 toward the interior of the semiconductor laminate 21 is reduced, and light can be efficiently reflected toward the upper surface 20U of the light-emitting element 20.

[0013] If the light-emitting device does not include a light-reflecting member, any organic matter, such as dust, present in the recess 10R of the base 10 is decomposed by the ultraviolet light emitted from the light-emitting element 20. As a result, the decomposed organic matter, mainly carbides, adheres to the upper surface 20U of the light-emitting element 20 or the surface of the fluororesin. In contrast, in this embodiment, a material containing boron nitride, which has excellent light resistance, is used for the light-reflecting member 30. When the base material of the light-reflecting member 30 is an inorganic material, the light-reflecting member 30 is porous with a plurality of fine pores. Furthermore, such a light-reflecting member 30 is exposed from the fluororesin at a position higher than the upper surface 20U of the light-emitting element 20. This allows the light-reflecting member 30 to adsorb organic matter, such as carbides, decomposed by the ultraviolet light emitted from the light-emitting element 20. In other words, the adhesion of organic matter to the upper surface of the light-emitting element 20 can be reduced. This improves light extraction from the light-emitting element 20. Furthermore, the plate-like particles of boron nitride reduce the occurrence of cracks in the light-reflecting member 30.

[0014] Furthermore, when the light-emitting element 20 is covered with a silicone resin or an epoxy resin, the silicone resin or the epoxy resin is easily degraded by the ultraviolet light emitted from the light-emitting element 20. In contrast, a fluororesin has little light absorption in the ultraviolet region and is transparent. Therefore, there is little loss of light when the light from the light-emitting element 20 passes through the fluororesin. Furthermore, the fluororesin has high resistance to ultraviolet light. In other words, the fluororesin is not easily degraded by the ultraviolet light emitted from the light-emitting element 20.

[0015] Each component will be described in detail below.

[0016] (Base) The base 10 has a recess 10R defined by a wall 10W and a bottom 10B. Specifically, the recess 10R is a space defined by an inner surface 10M of the wall 10W and an upper surface 10U of the bottom 10B. The wall 10W and the bottom 10B may be integral, or a separate wall 10W may be disposed on the bottom 10B. The light-emitting element 20 is bonded to the upper surface 10U of the bottom 10B via an adhesive member (not shown). The upper surface 10T of the wall 10W is located higher than the upper surface 20U of the light-emitting element 20. In other words, the height of the wall 10W from the upper surface 10U of the bottom 10B is greater than the height of the light-emitting element 20. For example, the height of the wall 10W from the upper surface 10U of the bottom 10B may be 1.1 to 2.5 times the height of the light-emitting element 20. The base 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 60 (first metal film 61) is disposed on an upper surface 10T of the wall portion 10W. The first metal film 61 is a member for facilitating bonding of a bonding member 50, which bonds the translucent member 40 (described later) to the wall portion 10W. Depending on the material of the bonding member 50, the first metal film 61 may be omitted. The base material 11 may be made of ceramics such as aluminum nitride, silicon nitride, or aluminum oxide. The conductive member 12 may be made of metals such as copper, aluminum, gold, or silver. The thickness of the conductive member 12 may be, for example, 5 μm or more and 17 μm or less. The conductive member 12 is disposed on an upper surface 10U of the bottom portion 10B and also on a lower surface 10F of the bottom portion 10B. The conductive member 12 arranged on the upper surface 10U of the bottom 10B and the conductive member 12 arranged on the lower surface 10F can be electrically connected by a conductive member arranged on the outer surface 10S of the base 10 or a via that penetrates the bottom 10B.

[0017] (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. In this embodiment, ultraviolet light refers to light having an emission peak wavelength of, for example, 100 nm or more and 280 nm or less. One or more ultraviolet light-emitting elements may be used in one light-emitting device. When multiple ultraviolet light-emitting elements are used, the ultraviolet light-emitting elements may have the same emission peak wavelength or different emission peak wavelengths. The light-emitting element 20 may be a semiconductor light-emitting element such as a light-emitting diode. The light-emitting element 20 includes a semiconductor laminate 21 and a pair of positive and negative electrodes 22. The semiconductor laminate 21 includes an element substrate made of, for example, sapphire and a semiconductor layer formed thereon. The light-emitting element 20 includes an upper surface 20U, a side surface 20L opposite the upper surface 20U, and a side surface 20S between the upper surface 20U and the lower surface 20L. The planar shape of the light-emitting element 20 may be a polygon, such as a triangle, a rectangle, 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 a side of about 600 μm, about 1400 μm, or about 1700 μm. The light emitting element 20 can also be a rectangle having long and short sides in a plan view. For example, it can be 1100 μm x 200 μm in size. The semiconductor laminate 21 includes an n-type semiconductor layer, a p-type semiconductor layer, and a light emitting layer sandwiched between them. A semiconductor laminate including such a light emitting layer can be, for example, In x Al y Ga 1-x-yN (0≦x, 0≦y, x+y≦1). The semiconductor laminate 21 may have a structure including one or more light-emitting layers between an n-type semiconductor layer and a 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 that order is repeated multiple times. When the semiconductor laminate 21 includes multiple light-emitting layers, the light-emitting layers may have different emission peak wavelengths, or may have light-emitting layers with the same emission peak wavelength. Note that the same emission peak wavelength includes cases where there is a variation of about several nanometers. The combination of emission peak wavelengths between the multiple light-emitting layers can be selected appropriately. For example, when the semiconductor laminate includes two light-emitting layers, a combination of a light-emitting layer with an emission peak wavelength of 365 nm and a light-emitting layer with an emission peak wavelength of 405 nm can be selected.

[0018] The light-emitting element 20 includes a pair of positive and negative electrodes 22 on the lower or upper surface of the semiconductor laminate 21. The electrodes 22 may be made of a good electrical conductor, such as gold, silver, tin, platinum, rhodium, titanium, aluminum, tungsten, palladium, nickel, or an alloy thereof. The electrodes 22 may include an ohmic electrode in contact with the lower or upper surface of the semiconductor laminate 21 and a pad electrode connected to the ohmic electrode and externally connected. The thickness of the electrodes 22 may be, for example, 10 μm to 50 μm. When the electrodes 22 are provided on the lower surface of the light-emitting element 20, they are fixed to and electrically connected to the base 10 by a conductive adhesive such as solder, a bump, or a metal paste. When the electrodes 22 are provided on the upper surface of the light-emitting element 20, as in the light-emitting device 100D shown in FIG. 4, they are fixed to the base 10 by an insulating adhesive such as epoxy resin and electrically connected to the conductive member 12 of the base 10 by a wire containing Au, Ag, or the like. When electrodes 22 are provided on the top and bottom of the light-emitting element 20, they are fixed to and electrically connected to the base 10 by a conductive adhesive member, and are also electrically connected using wires. Furthermore, the light-emitting device 100 may include a protective element in addition to the light-emitting element 20. Examples of the protective element include a Zener diode and a varistor. It is preferable that the protective element is entirely or partially embedded in the light-reflecting member 30.

[0019] (Fluorine-based resin) The fluororesin 70 is a material that is optically transparent to the light emitted from the light-emitting element 20. The transmittance of the fluororesin 70 for the emission peak wavelength emitted from the light-emitting element 20 is 80% or more and 99% or less. The structural unit of the fluororesin 70 is a polymer or copolymer having an aliphatic ring structure containing fluorine. An amorphous fluororesin is preferably used as the fluororesin 70. The fluororesin 70 covers part or all of the side surfaces of the light-emitting element 20. In particular, it is preferable to cover the side surfaces of the light-emitting element 20 that are closer to the bottom surface with the fluororesin. The fluororesin 70 may cover part or all of the upper surface 20U of the light-emitting element 20, or it may not cover part or all of the upper surface 20U of the light-emitting element 20. Examples of amorphous fluororesins include CYTOP (trade name: registered trademark) manufactured by AGC Corporation and Teflon (registered trademark) AF manufactured by Mitsui Chemours Fluoroproducts. The fluororesin may contain a phosphor that converts light from the light-emitting element into light of a different wavelength. Alternatively, the fluororesin may contain a light diffusing material that can diffuse light from the light-emitting element. The thickness of the fluororesin on the side surface of the light-emitting element may be, for example, 1 μm or more and 200 μm or less.

[0020] In a light-emitting device 100B shown in FIG. 2 as Modification 1, the fluorine-based resin 70 covers the side surface 20S and the upper surface 20U of the light-emitting element 20. Here, the upper surface of the fluorine-based resin 70 is curved. However, this is not limited thereto, and the upper surface of the fluorine-based resin 70 on the light-emitting element 20 may be flat, as in a light-emitting device 100C shown in FIG. 3 as Modification 2. Furthermore, as in a light-emitting device 100D shown in FIG. 4 as Modification 3, when the electrode 22 of the light-emitting element 20 is arranged with its electrode facing upward, a portion of the electrode 22 may be exposed from the fluorine-based resin 70. Furthermore, in the light-emitting device 100C shown in FIG. 3, the fluorine-based resin 70 covers the entire upper surface 10U of the bottom portion 10B of the base 10 (the bottom surface of the recess 10R). In other words, the fluorine-based resin 70 is located below the light-reflecting member 30. This reduces leakage due to potassium ions when the light-reflecting member 30 contains potassium, as described below.

[0021] (Light reflecting material) The light-reflecting member 30 is a member for reflecting light emitted from the light-emitting element 20. The light-reflecting member 30 can be disposed so as to contact 50% or more of the inner surface 10M of the wall portion 10W. In the example shown in FIG. 1B, the light-reflecting member 30 covers the entire inner surface 10M, from the top to the bottom. The base material of the light-reflecting member 30 may contain an organic material, an inorganic material, or both an organic material and an inorganic material. Fluorine-based resin can be used as the organic material. Alkali metal silicate can be used as the inorganic material. The light-reflecting member 30 is composed of, for example, a mixture containing boron nitride and alkali metal silicate. This mixture can be produced by mixing a powder mixture of boron nitride powder and silicon oxide powder with an alkaline solution (e.g., potassium hydroxide) and then heat-curing the mixture. When the alkaline solution is potassium hydroxide, heat curing causes silicon oxide and potassium hydroxide to react to produce potassium silicate, an alkali metal silicate. The light-reflecting member preferably contains boron nitride in a range of 30% by weight to 60% by weight. This reduces the shrinkage of the mixture during heat curing. The light-reflecting member 30 may also contain zirconium oxide in a range of 10% by weight to 40% by weight. This allows for efficient reflection of ultraviolet light emitted from the light-emitting element 20. Aluminum oxide may be used instead of boron nitride. The light-reflecting member 30 can be formed, for example, by covering part or all of the side surface of the light-emitting element 20 with fluorine-based resin 70, then placing the fluorine-based resin 70 on the inner surface 10M of the wall portion 10W and heating it. The light-reflecting member 30 may or may not be in contact with the fluorine-based resin 70.

[0022] (jointing material) The bonding member 50 is a member that bonds the base 10 and the light-transmitting member 40. When the base 10 and the light-transmitting member 40 include a metal film 60, the bonding member 50 bonds the base 10 and the light-transmitting member 40 via the metal film 60. 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 made of low-melting-point metals. It is particularly preferable to use solder, eutectic alloys such as alloys, and bumps that are resistant to degradation by ultraviolet light. The thickness of the bonding member 50 can be, for example, approximately 5 μm to 50 μm.

[0023] 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 or more and 17 μm or less. 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.

[0024] (wire) The wire 80 electrically connects the light emitting element 20 and the base 10. Au, Cu, Al, Ag, or an alloy containing any of these metals as a main component can be suitably used for the wire 80. It is preferable that a portion of the wire 80 is covered with a light reflecting member.

[0025] (Translucent member) The light-transmitting member 40 is a member that serves as the light extraction surface of the light-emitting device 100, and is bonded to the upper surface 10T of the wall portion 10W of the base 10 via a bonding member 50. The light-transmitting member 40 has the property of transmitting light from the light-emitting element. Here, light-transmitting refers to transmitting 70% or more of the light from the light-emitting element 20. 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. For example, glass, sapphire, etc. can be used as the light-transmitting member 40. A metal film 60 (second metal film 62) is provided on the lower surface of the light-transmitting member 40.

[0026] For example, aspects of the present invention are as follows. [Appendix 1] a base having a recess defined by a wall and a bottom; a light-emitting element having an upper surface, a lower surface opposite to the upper surface, and a side surface between the upper surface and the lower surface, the light-emitting element being disposed on the bottom so that the bottom and the lower surface face each other, the light-emitting element having an emission peak wavelength of 100 nm or more and 280 nm or less; a fluorine-based resin that covers the side surface of the light-emitting element; a light reflecting member containing boron nitride, the light reflecting member being in contact with the inner surface of the wall portion and the fluorine-based resin at a position away from the light emitting element; Equipped with The light emitting device, wherein the light reflecting member is exposed from the fluorine-based resin at a position higher than the upper surface of the light emitting element. [Appendix 2] 2. The light emitting device according to claim 1, wherein the light reflecting member is disposed to the side of the light emitting element so as to fill the entire space between the fluorine-based resin and the inner surface of the wall portion. [Appendix 3] 3. The light emitting device according to claim 1, wherein the fluorine-based resin covers the upper surface of the light emitting element. [Appendix 4] 4. The light emitting device according to claim 1, wherein the light reflecting member includes plate-like particles. [Appendix 5] 5. The light emitting device according to claim 1, wherein the light reflecting member contains the boron nitride in a range of 30% by weight to 60% by weight. [Appendix 6] 6. The light emitting device according to any one of claims 1 to 5, wherein the light reflecting member contains zirconium oxide in the range of 10% by weight to 40% by weight. [Explanation of symbols]

[0027] 100...Light emitting device 10...base (10R...recess, 10W...wall, 10T...upper surface of wall, 10M...inner surface of wall, 10S...outer surface of wall, 10B...bottom, 10U...upper surface of bottom (bottom surface of recess), 10F...lower surface of bottom) 11...Base material 12...Conductive member 20...light-emitting element (21...semiconductor laminate, 22...electrode, 20U...upper surface, 20S...side surface) 30...Reflective member 40...Translucent member 50... Joint material 60...metal film (61...first metal film, 62...second metal film) 70...Fluorine resin 80...wire

Claims

1. a base having a recess defined by a wall and a bottom; a light-emitting element having an upper surface, a lower surface opposite to the upper surface, and a side surface between the upper surface and the lower surface, the light-emitting element being disposed on the bottom so that the bottom and the lower surface face each other, the light-emitting element having an emission peak wavelength of 100 nm or more and 280 nm or less; a fluorine-based resin that covers the side surface of the light-emitting element; a light reflecting member containing boron nitride, the light reflecting member being in contact with the inner surface of the wall portion and the fluorine-based resin at a position away from the light emitting element; Equipped with The light emitting device, wherein the light reflecting member is exposed from the fluorine-based resin at a position higher than the upper surface of the light emitting element.

2. The light emitting device according to claim 1 , wherein the light reflecting member is disposed on the side of the light emitting element so as to fill the entire space between the fluorine-based resin and the inner surface of the wall portion.

3. 3. The light emitting device according to claim 1, wherein the fluorine-based resin covers the upper surface of the light emitting element.

4. The light emitting device according to claim 1 , wherein the light reflecting member includes plate-like particles.

5. 3. The light emitting device according to claim 1, wherein the light reflecting member contains the boron nitride in an amount of 30% by weight to 60% by weight.

6. 3. The light emitting device according to claim 1, wherein the light reflecting member contains zirconium oxide in a range of 10% by weight to 40% by weight.

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