Light-emitting device

Abstract

This light-emitting device is provided with: a light-emitting element; a wavelength conversion member disposed on top of the light-emitting element; and a light-transmissive member that is disposed on top of the wavelength conversion member, and has a first surface facing the wavelength conversion member and a second surface on the opposite side to the first surface. The light-transmissive member includes a first light-transmissive member having a first refractive index and having the first surface, and a second light-transmissive member having a second refractive index that is smaller than the first refractive index and having the second surface. The first light-transmissive member has a first structure part including a plurality of first protrusion parts or a plurality of first recess parts on the opposite side to the first surface, and the second light-transmissive member has a second structure part including a plurality of second protrusion parts or a plurality of second recess parts on the opposite side to the second surface. The interface between the first structure part and the second structure part includes a plurality of prism surfaces, and the arithmetic average roughness Ra of the second surface is smaller than the height of the second structure part.

Description

Light-emitting device

[0001] The present disclosure relates to light emitting devices.

[0002] A structure is known that includes a flip-chip semiconductor light-emitting device, a wavelength conversion structure disposed in a path of light extracted from the flip-chip semiconductor light-emitting device, and a substrate, the wavelength conversion structure being disposed between the substrate and the flip-chip semiconductor light-emitting device, the bottom surface of the substrate facing the wavelength conversion structure, and the top surface of the substrate being textured (for example, Patent Document 1).

[0003] Special table 2018-531517 publication

[0004] While the structure disclosed in Patent Document 1 can narrow the light distribution, the light extraction surface is textured, and there is room for improvement in the handling of the light emitting device.

[0005] An object of the present disclosure is to provide a light emitting device that has a narrow light distribution and is easy to handle.

[0006] The light emitting device of the present disclosure includes a light emitting element, a wavelength conversion member disposed on the light emitting element, and a light-transmitting member disposed on the wavelength conversion member, the light emitting element having a first surface facing the wavelength conversion member and a second surface opposite the first surface, the light-transmitting member having a first refractive index being a first refractive index and the first surface, and a second light-transmitting member having a second refractive index being smaller than the first refractive index and the second surface, the first light-transmitting member having a first structural portion including a plurality of first convex portions or a plurality of first concave portions on the side opposite the first surface, the second light-transmitting member having a second structural portion including a plurality of second convex portions or a plurality of second concave portions on the side opposite the second surface, the interface between the first structural portion and the second structural portion including a plurality of prism surfaces, and the arithmetic mean roughness Ra of the second surface being smaller than the height of the second structural portion.

[0007] According to one aspect of the present disclosure, it is possible to provide a light emitting device that has a narrow light distribution and improved handling properties.

[0008] 4 is a schematic cross-sectional view of a light-emitting device according to Embodiment 1. FIG. 5 is a schematic enlarged plan view showing a pattern of second convex portions. FIG. 6 is a schematic enlarged plan view showing another pattern of second convex portions. FIG. 7 is a schematic cross-sectional view of a light-emitting device according to Embodiment 2. FIG. 8 is an enlarged view showing an outline of a third structure portion. FIG. 9 is a schematic plan view showing the outline of the third structure portion as viewed from the first surface (31S) side. FIG. 10 is a schematic enlarged view of a first region. FIG. 11 is a schematic view showing a V-V cross section of FIG. 4. FIG. 12 is a schematic view showing a VI-VI cross section of FIG. 4. FIG. 13 is a schematic view showing another example of a third structure portion. FIG. 14 is a flowchart showing a method for manufacturing a light-emitting device. FIG. 15 is a schematic view showing an example of a method for manufacturing a light-emitting device. FIG. 16 is a schematic view showing an example of a method for manufacturing a light-emitting device. FIG. 17 is a schematic view showing an example of a method for manufacturing a third structure portion. FIG. 18 is a schematic view showing an example of a method for manufacturing a third structure portion. FIG. 19 is a schematic cross-sectional view of a light-emitting device according to Modification 1. FIG. 19 is a schematic cross-sectional view of a light-emitting device according to Modification 2. FIG. 19 is a schematic cross-sectional view of a light-emitting device according to Modification 3. FIG. 19 is a diagram showing an example of a part surrounded by a dashed line in a light-emitting device according to Modification 3. FIG. 10 is a schematic cross-sectional view of a light emitting device of a comparative example.

[0009] Hereinafter, embodiments and examples for carrying out the present invention 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 invention, and unless otherwise specified, the present invention is not limited to the following.

[0010] In each drawing, components having the same function may be assigned the same symbol. For convenience, the embodiments and examples may be shown separately to facilitate explanation or understanding of the main points, but partial substitution or combination of the configurations shown in different embodiments and examples is possible. In the following embodiments and examples, 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 sequentially in each embodiment or example. The size and positional relationship of components shown in each drawing may be exaggerated to clarify the explanation.

[0011] In this specification, the term "process" does not only refer to an independent process, but also includes processes that cannot be clearly distinguished from other processes as long as the intended purpose of the process is achieved. Furthermore, the upper and lower limits of the numerical ranges described in this specification can be arbitrarily selected and combined from the numerical values ​​exemplified as numerical ranges. The following describes embodiments of the present invention in detail. However, the embodiments described below are intended to exemplify light-emitting devices and manufacturing methods thereof in order to embody the technical concept of the present invention, and the present invention is not limited to the light-emitting devices and manufacturing methods thereof described below.

[0012] 1A is a schematic cross-sectional view of a light-emitting device 1A. The light-emitting device 1A includes a light-emitting element 10, a wavelength conversion member 20 disposed on the light-emitting element 10, a light-transmitting member 30 disposed on the wavelength conversion member 20 and having a first surface 31S facing the wavelength conversion member 20, and a second surface 35S on the opposite side of the first surface 31S. The light-transmitting member 30 includes a first light-transmitting member 31 having a first refractive index and having the first surface 31S, and a second light-transmitting member 35 having a second refractive index smaller than the first refractive index and having the second surface 35S. The first light-transmitting member 31 includes a first structural portion 32 including a plurality of first convex portions 321 or a plurality of first concave portions 322 on the side opposite the first surface 31S. The second light-transmitting member 35 includes a second structural portion 36 including a plurality of second convex portions 361 or a plurality of second concave portions 362 on the side opposite the second surface 35S. The interface between the first structure portion 32 and the second structure portion 36 includes a plurality of prism surfaces 40, and the arithmetic mean roughness Ra of the second surface 35S is smaller than the height h of the second structure portion 36.

[0013] As a result, the light is reflected by the prism surface 40, and the light emitting device 1A has a narrowed light distribution.

[0014] (Light-emitting element 10) The light-emitting element 10 may be a light-emitting diode. The light-emitting element 10 includes a semiconductor laminate 12. The semiconductor laminate 12 includes an n-side semiconductor layer, a p-side semiconductor layer, and an active layer disposed between the n-side semiconductor layer and the p-side semiconductor layer. The n-side semiconductor layer includes an n-type semiconductor layer. The p-side semiconductor layer includes a p-type semiconductor layer. The active layer may have a single quantum well structure or a multiple quantum well structure. The semiconductor laminate 12 may be a nitride semiconductor. The light-emitting element 10 may have an emission peak wavelength of, for example, 360 nm or more and 680 nm or less.

[0015] The semiconductor stack 12 may include a first stack including a first n-side semiconductor layer, a first p-side semiconductor layer, and a first active layer disposed between the first n-side semiconductor layer and the first p-side semiconductor layer, a second stack including a second n-side semiconductor layer, a second p-side semiconductor layer, and a second active layer disposed between the second n-side semiconductor layer and the second p-side semiconductor layer, and a third n-side semiconductor layer disposed between the first stack and the second stack. The concentration of n-type impurities contained in the third n-side semiconductor layer is higher than the concentrations of n-type impurities contained in the first n-side semiconductor layer and the second n-side semiconductor layer. The third n-side semiconductor layer is disposed between the first p-side semiconductor layer and the second n-side semiconductor layer, and is disposed so as to form interfaces with each of them.

[0016] In this specification, light having a peak emission wavelength of 420 nm or more and less than 480 nm is referred to as "blue light," light having a peak emission wavelength of 480 nm or more and less than 560 nm is referred to as "green light," light having a peak emission wavelength of 560 nm or more and less than 590 nm is referred to as "yellow light," and light having a peak emission wavelength of 590 nm or more and less than 680 nm is referred to as "red light."

[0017] The light-emitting element 10 includes a first electrode 13 and a second electrode 14. The first electrode 13 is a negative electrode, and the second electrode 14 is a positive electrode. The light-emitting element 10 may further include a substrate 11. In this case, the semiconductor stack 12 is disposed on the substrate 11. The substrate 11 is a growth substrate for the semiconductor stack 12. The substrate 11 may be a sapphire substrate. The substrate 11 may be removed after the semiconductor stack 12 is grown. Furthermore, when the light-emitting element 10 includes the first stack and the second stack, the first electrode 13 is connected to the first n-side semiconductor layer, and the second electrode 14 is connected to the second p-side semiconductor layer.

[0018] (Wavelength conversion member 20) The wavelength conversion member 20 is disposed on the light emitting element 10. As shown in FIG. 1A , the wavelength conversion member 20 may be bonded to the light emitting element 10 via an adhesive 21. Alternatively, the wavelength conversion member 20 may be directly bonded to the light emitting element 10 so as to form an interface between the bonding surface of the wavelength conversion member 20 and the bonding surface of the light emitting element 10. For example, the wavelength conversion member 20 contains a phosphor and receives light emitted from the light emitting element 10 to emit light of a different wavelength. The wavelength conversion member 20 may be a ceramic containing a phosphor. The phosphor may be, for example, an yttrium aluminum garnet (YAG) phosphor. The activator is cerium. Alternatively, the phosphor may be a phosphor in which at least a portion of the yttrium in YAG is substituted with gadolinium, terbium, or lutetium. Alternatively, the phosphor may be a phosphor in which at least a portion of the aluminum in YAG is substituted with gallium. The ceramic containing a phosphor may contain, in addition to the phosphor, aluminum oxide, YAP (yttrium aluminum perovskite), or the like as a binder. When the wavelength conversion member 20 is made of ceramic containing a YAG phosphor, yellow light emission can be obtained efficiently.

[0019] The ceramic containing a phosphor may include ceramics of a phosphor in which aluminum nitride is doped with europium, or ceramics of a phosphor in which aluminum nitride is doped with manganese. These emit green or red light and have excellent heat dissipation properties. In addition to phosphors, the wavelength conversion member 20 may also be made of gallium nitride doped with europium. Red light emission with a narrow linewidth can be obtained. The wavelength conversion member 20 may also include a luminescent material having a perovskite structure or quantum dots having a chalcopyrite structure.

[0020] In the light emitting device 1A, light emitted by the light emitting element 10 and light whose wavelength has been converted by the wavelength conversion member 20 are extracted from the second surface 35S. The mixture of these colors may be white. Here, white in this specification refers to a color temperature (including correlated color temperature) of 3500 K or more and 6000 K or less. The light emitting device 1A may include a nitride semiconductor light emitting element as the light emitting element 10, and may further be ceramic containing a YAG phosphor as the wavelength conversion member 20. In this way, a light emitting device 1A that emits white light may be obtained.

[0021] (Adhesive 21) The adhesive 21 is disposed between the light emitting element 10 and the wavelength conversion member 20 to bond them together. In Fig. 1A, the adhesive 21 extends to the side surfaces of the substrate 11 and the semiconductor laminate 12, forming fillets. This allows light extracted from the side surfaces of the light emitting element 10 to be reflected toward the wavelength conversion member 20, thereby increasing the light extraction efficiency. The material of the adhesive 21 may be, for example, an epoxy resin, a silicone resin, or a polysilazane resin.

[0022] (Light-Transmissive Member 30) The light-transmissive member 30 is disposed on the wavelength conversion member 20. In FIG. 1A , the light-transmissive member 30 is disposed on the wavelength conversion member 20 via a second resin 62. The light-transmissive member 30 has a first surface 31S facing the wavelength conversion member 20 and a second surface 35S opposite the first surface 31S. The second surface 35S is a light extraction surface. The light-transmissive member 30 includes a first light-transmissive member 31 and a second light-transmissive member 35. As described below, the light-transmissive member 30 includes a prism surface 40 at the interface between the first light-transmissive member 31 and the second light-transmissive member 35. In other words, a prism formed by the first light-transmissive member 31 and the second light-transmissive member 35 is embedded in the light-transmissive member 30. Compared to a case where a prism is not provided, this prism narrows the light distribution of the light extracted from the light-emitting device 1A.

[0023] (First light-transmissive member 31) The first light-transmissive member 31 includes a first surface 31S facing the wavelength conversion member 20. The first light-transmissive member 31 has a first refractive index. As shown in the area surrounded by the dotted line in FIG. 1A, the first light-transmissive member 31 has a first structure portion 32 including a plurality of first convex portions 321 or a plurality of first concave portions 322 on the side opposite to the first surface 31S. The first light-transmissive member 31 is made of, for example, Al ｘ Ga １－ｘ N (0≦x≦1). The first light-transmissive member 31 may be an oxide such as tantalum oxide, niobium oxide, hafnium oxide, zirconium oxide, or titanium oxide. In a cross-sectional view perpendicular to the second surface 35S, the maximum thickness of the first light-transmissive member 31 is 2 μm or more and 7 μm or less. In this specification, the width in the normal direction to the second surface 35S is referred to as the thickness. Furthermore, the width in the direction parallel to the second surface 35S is referred to as the width.

[0024] (Second Light-Transmitting Member 35) The second light-transmitting member 35 has a second surface 35S on the side opposite the first surface 31S. The refractive index of the second light-transmitting member 35 is a second refractive index smaller than the first refractive index. As shown in the area surrounded by the dotted line in FIG. 1A , the second light-transmitting member 35 has a second structure 36 on the side opposite the second surface 35S, the second structure 36 including a plurality of second convex portions 361 or a plurality of second concave portions 362. Flat surfaces 41S are provided between the plurality of second convex portions 361 or between the plurality of second concave portions 362. In a cross-sectional view perpendicular to the second surface 35S, the maximum thickness of the second light-transmitting member 35 is 100 μm or more and 300 μm or less. The material of the second light-transmitting member 35 is, for example, sapphire or glass. The second light-transmitting member may be, for example, a patterned sapphire substrate (PSS), and the second structure 36 may include second convex portions 361 formed of a PSS pattern. The height of the second protrusions 361 is, for example, 1 μm or more and 3 μm or less. The maximum thickness of the second protrusions 361 is, for example, 1 μm or more and 10 μm or less. The distance between the centers of adjacent second protrusions 361 is, for example, 2 μm or more and 10 μm or less. The height of the second protrusions 361 may be 0.7 times or more and 3 times or less, preferably 1.2 times or more and 2.1 times or less, half the maximum thickness.

[0025] The second convex portions 361 may have a predetermined periodic structure. Fig. 1B is a schematic plan view showing the pattern of the second convex portions 361. As shown in Fig. 1B, the periodic structure may, for example, form a triangular lattice with respect to a plane parallel to the second surface 35S. Alternatively, the second convex portions 361 or the second concave portions 362 may have a line-and-space pattern extending in a predetermined direction.

[0026] 1C is a schematic plan view showing another pattern of the second convex portions 361. As shown in FIG. 1C, the line-and-space pattern may have multiple patterns extending in different directions. For example, three types of line-and-space patterns rotated by 120° from each other and a pattern that is line-symmetric to these may be provided. In this way, by providing the second convex portions 361 extending in various directions, a prism can be applied to light incident from various directions, thereby enabling an efficient narrow light distribution.

[0027] The interface between the first structure 32 and the second structure 36 includes a plurality of prism surfaces 40. As a result, the light emitted from the light emitting element 10 and the light whose wavelength is converted by the wavelength conversion member 20 are refracted when passing through the prism surfaces 40, narrowing the light distribution of the light extracted from the light emitting device 1A. In addition, the first refractive index is greater than the second refractive index. Therefore, light incident on the second light-transmissive member 35 from the first light-transmissive member 31 is easily affected by the prism effect, and the light distribution is efficiently narrowed.

[0028] The arithmetic mean roughness Ra of the second surface 35S of the light-transmitting member 30 is smaller than the height of the second structural portion 36. In FIG. 1A, the height of the second structural portion 36 refers to the height h from the top to the bottom of the second structural portion 36. In the light-emitting device 1A shown in FIG. 1A, the interface between the first structural portion 32 and the second structural portion 36 includes not only a prism surface 40 but also a flat surface 41S. Therefore, the height h is the height h from this flat surface 41S to the tip of the second structural portion 36. This makes the second surface 35S flatter than the prism surface 40, making it easier to handle. For example, when mounting the light-emitting device 1A on a wiring board for a headlamp, lighting, or the like, the second surface 35S of the light-transmitting member 30 of the light-emitting device 1A may be sucked with a nozzle of a robot hand and carried to a predetermined position. In this case, the flatness of the second surface 35S improves handling by the robot hand. The arithmetic mean roughness Ra of the second surface 35S may be, for example, 1 nm or more and 200 nm or less, 1 nm or more and 150 nm or less, or 1 nm or more and 100 nm or less.

[0029] As described above, in the light emitting device 1A of the first embodiment, the second surface 35S is flatter than the prism surface 40, and the prism surface 40 is formed at the interface between the first light-transmissive member 31 and the second light-transmissive member 35. Therefore, the distribution of light extracted from the light emitting device 1A is narrowed by the prism, and handling is also improved.

[0030] The first light-transmitting member 31 is made of Al. ｘ Ga １－ｘ N (0≦x≦1), and the second light-transmissive member 35 is preferably sapphire, which increases the difference in refractive index between the first light-transmissive member 31 and the second light-transmissive member 35, thereby enabling the light distribution to be narrowed efficiently.

[0031] (Wiring Substrate 60) The wiring substrate 60 has formed thereon a first wiring 131 connected to the first electrode 13 and a second wiring 141 connected to the second electrode 14. The wiring substrate 60 may be made of a multilayer wiring ceramic such as a low-temperature co-fired ceramic, for example.

[0032] (First Resin 61) The first resin 61 is disposed on the wiring substrate 60 of the light emitting device 1A, and covers the side surfaces of the light emitting element 10, the space between the wiring substrate 60 and the light emitting element 10, and the side surfaces of the wavelength conversion member 20. The first resin 61 may be, for example, a silicone resin or an epoxy resin. The first resin 61 contains a light-reflective material such as titanium oxide, aluminum oxide, or boron nitride, and reflects light emerging from the side surfaces of the light emitting element 10 and the wavelength conversion member 20 toward the light-transmitting member 30, thereby increasing the light extraction efficiency from the second surface 35S.

[0033] (Second Resin 62) The second resin 62 is disposed on the first resin 61 and forms a gap 22, which will be described later, together with the light-transmitting member 30 and the wavelength conversion member 20. The second resin 62 supports the light-transmitting member 30. The second resin 62 may be, for example, a silicone resin or an epoxy resin. The second resin 62 contains a light-reflective material such as titanium oxide, aluminum oxide, or boron nitride. The second resin 62 reflects light emitted from the light-emitting element 10 and the wavelength conversion member 20 toward the light-transmitting member 30, thereby increasing the light extraction efficiency from the second surface 35S. The second resin 62 may be made of the same material as the first resin 61. Alternatively, the second resin 62 may be integrated with the first resin 61.

[0034] (Third Resin 63) The third resin 63 covers the side surfaces of the first light-transmissive member 31 and the second light-transmissive member 35. The third resin 63 may be, for example, a silicone resin or an epoxy resin. The third resin 63 contains a light-reflective material such as titanium oxide, aluminum oxide, or boron nitride, and reflects light emerging from the side surfaces of the light-transmissive member 30 toward the second surface 35S, thereby increasing the light extraction efficiency from the second surface 35S. The material of the third resin 63 may be the same as the materials of the first resin 61 and the second resin 62. Furthermore, the first resin 61, the second resin 62, and the third resin 63 may be integrated.

[0035] (Gap 22) The gap 22 is filled with air, forming an air gap. The refractive index of air is approximately 1, which is smaller than the first and second refractive indices. Therefore, light traveling through the wavelength conversion member 20 passes through the gap 22 at least once before entering the translucent member 30. Snell's law dictates that at the boundary between two media, the tangential component of the wave vector of light with respect to the boundary surface remains unchanged before and after refraction. Therefore, the tangential component of the wave vector also remains unchanged at the interface between the wavelength conversion member 20 and the gap 22. The same is true for the interface between the gap 22 and the first translucent member 31. By providing the gap 22 between the wavelength conversion member 20 and the first translucent member 31, the air, which has a refractive index of approximately 1, restricts the tangential component of the wave vector at the interface. This restricts the direction of light refracted toward the first translucent member 31, thereby increasing the component incident at an angle suitable for the prism. As a result, the light distribution of the light extracted from the light emitting device 1A can be narrowed. The height of the gap 22 should be at least greater than the wavelength of the light emitted from the light emitting element 10. The height of the gap 22 may be, for example, 1 μm or more and 100 μm or less, and preferably 1 μm or more and 10 μm or less.

[0036] In the light-emitting device 1A of the first embodiment, as shown in FIG. 1A , the upper surface 62S of the second resin is positioned higher than the upper surface 20S of the wavelength conversion member 20. The light-transmitting member 30 is supported by the upper surface 62S of the second resin 62. In a direction parallel to the first surface 31S of the light-transmitting member 30, the width of the light-transmitting member 30 is greater than the width of the wavelength conversion member 20. This allows the light-transmitting member 30 to be supported by the upper surface 62S of the second resin 62. In this case, the space surrounded by the light-transmitting member 30, the wavelength conversion member 20, and the second resin 62 is the gap 22. The second resin 62 is preferably a silicone resin. The shape of the second resin 62 can be maintained while the light-transmitting member 30 is bonded by the second resin 62. A third resin 63 is also disposed on the upper surface 62S of the second resin 62.

[0037] <Embodiment 2> Fig. 2A is a schematic cross-sectional view showing a light emitting device 1B of embodiment 2. The light emitting device 1B of embodiment 2 differs from the light emitting device 1A of embodiment 1 in that it has a third structural portion 50 on the first surface 31S side. The third structural portion 50 will be described using Fig. 2B. Fig. 2B is a schematic enlarged view of a portion of the third structural portion 50 in Fig. 2A.

[0038] (Third Structure 50) The first translucent member 31 has a third structure 50 including a plurality of third convex portions 501 extending from the first surface 31S toward the wavelength conversion member 20 or a plurality of third concave portions 502 extending from the first surface 31S toward the prism surface 40. The center-to-center distance between adjacent third convex portions 501 and the center-to-center distance between adjacent third concave portions 502 are at least equal to or less than the wavelength in air of the light emitted from the wavelength conversion member 20, and preferably equal to or less than the wavelength in air of the light emitted by the light-emitting element. When light passes through the third structure 50, a local phase difference occurs in the light, causing the light to change its traveling direction. In this way, changing the traveling direction of the light by the third structure 50 makes it easier for the light to enter the prism surface 40 at the interface between the first structure 32 and the second structure 36, thereby narrowing the light distribution of the light extracted from the light-emitting device 1B. The third structure 50 can also be considered a so-called metasurface.

[0039] As described in the first embodiment, when the maximum height of the first light-transmissive member 31 is 2 μm or more and 7 μm or less and the height of the prism surface 40 is 1 μm or more and 3 μm or less, the height h1 from the bottom surface of the third convex portion 501 or the third concave portion 502 of the third structural portion 50 to the flat surface 41S at the interface between the first structural portion 32 and the second structural portion 36 may be more than 0 μm and 2 μm or less. This makes it possible to bring the prism surface 40 and the third structural portion 50 closer to each other and increase the proportion of light that passes through the third structural portion 50 and is incident on the prism surface 40.

[0040] FIG. 3 is a schematic plan view of the general shape of the third structure 50 as viewed from the first surface 31S. The first and second directions represent directions within the plane of the first surface 31S. As shown in FIG. 3 , the third structure 50 has a plurality of first regions 51 and a plurality of second regions 52 in a planar view. In the first region 51, the widths of adjacent third convex portions 501 or third concave portions 502 in the first direction change. This imparts a phase difference to the first-direction component of light. The wavefront direction of light passing through the third structure 50 in the first region 51 changes at a predetermined angle relative to the first direction in accordance with the imparted phase difference. In other words, the traveling direction of light can be changed at a predetermined angle relative to the first direction. In the second region 52, the widths of adjacent third convex portions 501 or third concave portions 502 in a second direction different from the first direction change. This imparts a phase difference to the second-direction component of light. As with the first region 51, the traveling direction of light can be changed relative to the second direction. 3 indicates the direction in which the width of the third convex portion 501 or the third concave portion 502 changes in the first region 51 and the second region 52. In the example of FIG. 3, the first direction and the second direction are perpendicular to each other.

[0041] This can be utilized to increase the component of light incident at an angle that is advantageous for the prism surface 40. Therefore, providing the third structure 50 enhances the effect of narrowing the light distribution provided by the prism surface 40. Furthermore, by having the first region 51 and the second region 52, the third structure 50 can change the traveling direction of light in each of the first and second directions. Because the prism surface 40 faces multiple directions, changing the traveling direction of light in multiple directions using the first region 51 and the second region 52 further enhances the effect of narrowing the light distribution provided by the prism surface 40. Furthermore, the third structure 50 in each of the multiple first regions 51 and the multiple second regions 52 can cause light to travel in multiple directions, so light is incident on the prism from various directions, reducing chromaticity deviation.

[0042] In the example shown in FIG. 3 , the first region 51 and the second region 52 are adjacent to each other, and the first region 51 and the second region 52 are repeatedly formed. The symbol "..." in the figure indicates that the first region 51 and the second region 52 are repeatedly formed. The width w1 of the first region 51 and the width w2 of the second region 52 are, for example, 1 μm or more and 50 μm or less. As such, each of the first region 51 and each of the second region 52 are minute regions. Therefore, at least one of the light emitted from the light emitting element 10 and the light whose wavelength is converted by the wavelength conversion member 20 passes through at least one of the first region 51 and the second region 52, thereby increasing the component incident at an angle that is advantageous to the prism surface 40.

[0043] Next, details of the third structural portion 50 will be described. Fig. 4 is a schematic enlarged view of the first region 51. The third structural portion 50 in the first region 51 has a plurality of regions U in which the widths of adjacent third convex portions 501 or third concave portions 502 monotonically increase and monotonically decrease in the first direction.

[0044] In region U, as shown by the dotted line, third convex portions 501 or third concave portions 502 are provided with a predetermined width within a virtual square region with a side length of a. This region is called a unit cell uc. In FIG. 4 , region U includes a plurality of unit cells uc. Region U includes third convex portions 501 or third concave portions 502 with a radius R1 to third convex portions 501 or third concave portions 502 with a radius Rn. In region U, the center-to-center distance between adjacent third convex portions 501 or third concave portions 502 is at least equal to or less than the wavelength in air of light emitted from the wavelength conversion member 20. That is, the spacing a between unit cells uc is at least equal to or less than the wavelength in air of light emitted from the wavelength conversion member 20, preferably equal to or less than the wavelength in air of light emitted by the light-emitting element. The spacing a may be, for example, 150 nm or more and 600 nm or less, preferably 150 nm or more and 500 nm or less. In this example, the width of adjacent third convex portions 501 or third concave portions 502 in the second direction is constant. Note that "constant" here includes variations due to errors in the manufacturing process. This region U is repeatedly formed in the first direction and the second direction. As in FIG. 3, the symbol "..." indicates that the region U is repeated. Next, the structure of region U will be described in detail using FIGS. 5 and 6.

[0045] FIG. 5 is a schematic diagram showing the V-V cross section of FIG. 4 . This is a cross section of one region U. Here, we will explain a case where the third structure 50 has multiple third recesses 502 extending from the first surface 31S toward the prism surface 40. For simplicity, only the cross section of the first light-transmissive member 31 is shown. The third structure 50 has multiple regions where the width of adjacent third recesses 502 monotonically increases and monotonically decreases. The center-to-center distance between adjacent third recesses 502 is constant at a. The width of the third recesses 502 varies as follows: R1, R2, R3, ... Ri, ... Rj, Rj+1, ... Rn-1, Rn. In the example of FIG. 5 , R1 > R2 > R3 > ... > Ri, and Rj < Rj+1 < ... < Rn-1 < Rn. The maximum width of the third recesses may be, for example, 140 nm or more and 480 nm or less. The depth h2 of the third recess may be 900 nm or more and 2000 nm or less.

[0046] Because R2 is smaller than R1, the effective refractive index of a unit cell uc including a third recess 502 with a width of R2 is greater than the effective refractive index of a unit cell uc including a third recess 502 with a width of R1. Similarly, because R3 is smaller than R2, the effective refractive index of a unit cell uc including a third recess 502 with a width of R3 is greater than the effective refractive index of a unit cell uc including a third recess 502 with a width of R2. Comparing adjacent unit cells uc in this manner reveals that the effective refractive indices of the unit cells uc differ due to the different widths of the third recess 502. When the effective refractive index differs between unit cells uc, light passing through the third structure 50 is affected by the different effective refractive indices at different positions in the unit cells uc, resulting in a change in phase velocity and a change in the wavefront direction. In other words, the light propagation direction changes. In the case of the first region 51, the light propagation direction changes from the normal to the interface between the flat surface 502S adjacent to the opening of the third recess 502 and the gap 22 toward the first direction. The flat surface here refers to a surface having a degree of flatness that can be obtained by crystal growth. By appropriately setting the width of the third convex portion 501 or the third concave portion 502 so that the effective refractive index of each unit cell uc changes by a desired value, the third structure portion 50 is given the desired function of an optical element.

[0047] Next, the function of the optical element provided by region U will be described. In FIGS. 4 and 5 , there is a region in which the width of the third recess 502 monotonically decreases in the first direction, such as R1 > R2 > R3 > ... > Ri .... Furthermore, there is a region in which the width of the third recess 502 monotonically increases in the first direction, such as ... Rj < Rj+1 < ... < Rn-1 < Rn. This provides region U with the effect of a triangular prism, as shown in FIG. 5 . FIG. 5 schematically illustrates the shape of a triangular prism represented by region U, superimposed on a cross-sectional view taken along line V-V. As described above, the region in which the width of the third recess 502 monotonically decreases functions as one side of a triangular prism, and the region in which the width of the third recess 502 monotonically increases functions as the other side of the triangular prism. Thus, by providing the third structure 50 with the function of a triangular prism, the traveling direction of light is changed for each hypotenuse, allowing light to efficiently enter the prism surface 40. The length of the region where the width of the third recess 502 monotonically increases or decreases in the first direction may be, for example, 500 nm or more and 1100 nm or less, preferably 500 nm or more and 800 nm or less.

[0048] The third structure 50 is not limited to a triangular prism, and may have the effect of a blazed diffraction grating or a condenser lens. Furthermore, the number of unit cells uc in the region U does not need to be an integer, as long as a predetermined function is provided. That is, the region U may end in the middle of a unit cell uc, and the next region U may begin from the continuation of that unit cell uc.

[0049] FIG. 6 is a schematic cross-sectional view taken along line VI-VI in FIG. 4. For simplicity of illustration, only the cross section of the first light-transmissive member 31 is shown. FIG. 4 is a cross-sectional view of the third recess 502 having a width R1. As shown in FIG. 6, the width of the third recess 502 of adjacent unit cells uc in the second direction is constant at R1. The dotted lines indicate that this third recess 502 is repeated. Therefore, in this example, the wavefront of the third structure portion 50 in the first region 51 does not change in the second direction. Therefore, the orientation does not change in the second direction.

[0050] In the first region 51, the width of the third recess 502 changes in the first direction, and the light changes its traveling direction relative to the first direction. This increases the component of light incident at an angle at which the prism surface 40 is advantageous, and therefore, by providing the third structure 50, the prism surface 40 can more efficiently narrow the light distribution.

[0051] 4 to 6 , the first region 51 has been described, but the second region 52 is similar except for the following points. That is, the second region 52 differs from the first region 51 in that the width of the third recess 502 changes in the second direction, but does not change in the first direction. In the case of the second region 52, the traveling direction of light changes from the normal to the interface between the gap 22 and the flat surface 502S adjacent to the opening of the third recess 502 to the direction toward the second direction.

[0052] The third structure 50 of the light emitting device 1B has a plurality of first regions 51 that change the direction of light propagation relative to the first direction and a plurality of second regions that change the direction of light relative to the second direction. This allows light to propagate in a plurality of directions, so that light is incident on the prism from various directions, thereby reducing color unevenness in the light extracted from the light emitting device 1B.

[0053] 5 and 6, the third structural portion 50 has been described as the third recess 502 by way of example, but the third structural portion 50 may also be the third convex portion 501. In this case, in order to impart the function of a triangular prism as shown in Fig. 5 to the third structural portion 50, the widths R1, R2, R3, ... Ri, ... Rj, Rj+1, ... Rn-1, Rn of the third convex portion 501 may be reversed from those of the third recess 502. In other words, R1<R2<R3< ... <Ri, and Rj>Rj+1> ... >Rn-1>Rn.

[0054] FIG. 7 shows a modified example of the general shape of the third structural element 50. As shown in FIG. 7, the third structural element 50 differs from the example shown in FIG. 3 in that it includes a third region 53 and a fourth region 54 in addition to the first region 51 and the second region 52. The third region 53 has a plurality of regions u in which the widths of adjacent third convex portions 501 or third concave portions 502 monotonically increase and monotonically decrease in a third direction different from the first direction and the second direction. The fourth region 54 has a plurality of regions u in which the widths of adjacent third convex portions 501 or third concave portions 502 monotonically increase and monotonically decrease in a fourth direction different from the first direction, the second direction, and the third direction. In the first region 51 to the fourth region 54, the direction of hatching in FIG. 7 indicates the direction in which the widths of the third convex portions 501 or third concave portions 502 change. In FIG. 7, the third direction is rotated 45° clockwise from the first direction toward the second direction. The fourth direction is rotated 45° counterclockwise from the first direction toward the second direction. Because prism surface 40 faces multiple directions, there are multiple directions in which the width of third convex portion 501 or third concave portion 502 changes, which increases the component of light that is incident on prism surface 40 at an advantageous angle.

[0055] <Manufacturing Method> A manufacturing method for the light emitting device 1A of embodiment 1 will be described. As shown in Fig. 8, the manufacturing method for the light emitting device 1A includes step S1 of preparing a light emitting section A, step S2 of preparing a light-transmitting member 30, and step S3 of arranging the light-transmitting member 30 in the light emitting section 100A. This makes it possible to manufacture a light emitting device 1A with a narrow light distribution. Below, the manufacturing method for the light emitting device 1A will be described with reference to Fig. 9A.

[0056] 9A , the light-emitting unit 100A includes a wiring substrate 60, a light-emitting element 10 connected to the wiring substrate 60, a wavelength conversion member 20 disposed on the light-emitting element, a first resin 61 covering the side surfaces of the light-emitting element 10, the area between the light-emitting element 10 and the wiring substrate 60, and the side surfaces of the wavelength conversion member 20, and a second resin 62 disposed on the first resin 61 and having an upper surface 62S positioned higher than the upper surface of the wavelength conversion member 20.

[0057] (Step of Preparing Light-Emitting Devices 10) In this step, a wafer is first prepared, which is an integrated wafer of multiple substrates 11 that will be singulated. When preparing nitride semiconductor light-emitting devices, the wafer to be prepared is, for example, a sapphire wafer. Next, an n-side semiconductor layer, an active layer, and a p-side semiconductor layer that constitute the semiconductor stack 12 are grown on the upper surface of the wafer. The n-side semiconductor layer includes an n-type semiconductor. The p-side semiconductor layer includes a p-type semiconductor. The semiconductor stack is obtained by growing using a chemical vapor deposition method or a physical vapor deposition method. The chemical vapor deposition method may be a metalorganic chemical vapor deposition (MOCVD) method. The physical vapor deposition method may be a molecular beam epitaxy method or a sputtering method. Next, portions of the p-side semiconductor layer and the active layer are removed in regions corresponding to the individual light-emitting devices 10 to expose the n-side semiconductor layer. The wafer may also include a step of adjusting the thickness to a desired value by, for example, mechanical polishing or chemical mechanical polishing (CMP). This step may be performed on the underside of the wafer after the semiconductor stack 12 has been grown on the upper side of the wafer, or the wafer may be removed after the semiconductor stack 12 has been grown.

[0058] (Step of Preparing Wavelength Conversion Member 20) In this step, a plate (i.e., wavelength conversion member plate) made of the wavelength conversion member 20 is prepared. The wavelength conversion member plate may be, for example, a YAG single crystal phosphor, a YAG phosphor epitaxially grown on a substrate, or a ceramic containing a YAG phosphor and aluminum oxide (or YAP) as a binder. The type of phosphor can be selected as appropriate. The manufacturing method for each wavelength conversion member plate can be selected as appropriate, such as chemical vapor deposition, unidirectional solidification, or pulse current sintering. The step of preparing the wavelength conversion member 20 may include a step of grinding and polishing the wavelength conversion member plate to a desired thickness so that light of a desired chromaticity is emitted from the light emitting device 1A. In the step of preparing the wavelength conversion member 20, the wavelength conversion member plate may be singulated into a plurality of wavelength conversion members 20. Note that the order of the steps of preparing the light emitting element 10 and preparing the wavelength conversion member 20 may be reversed.

[0059] (Step of Forming First Resin 61 and Second Resin 62) First, the first electrode 13 and the second electrode 14 are arranged on the wiring substrate 60. Next, the first electrode 13 and the second electrode 14 are connected to the light-emitting element 10. The first electrode 13 is connected to the n-side semiconductor layer, and the second electrode 14 is connected to the p-side semiconductor layer. Next, the light-emitting element 10 and the wavelength conversion member 20 are bonded together with an adhesive 21. Instead of bonding them together with the adhesive 21, the light-emitting element 10 and the wavelength conversion member 20 may be directly bonded. Then, the first resin 61 is arranged between the light-emitting element 10 and the wiring substrate 60, covering the side surfaces of the light-emitting element 10 and the side surfaces of the wavelength conversion member 20. The top surface of the first resin 61 may be at the same height as the top surface 20S of the wavelength conversion member 20. Next, the second resin 62 is formed on the first resin 61. At this time, the second resin 62 is arranged so that the top surface 62S of the second resin is higher than the top surface 20S of the wavelength conversion member 20. The upper surface 20S of the wavelength conversion member 20 is located inside the opening surrounded by the first resin 61 .

[0060] (Step of Preparing Light-Transmitting Member 30) In this step, a wafer is prepared in which a second light-transmitting member 35 is disposed on a first light-transmitting member 31. The surface of the first light-transmitting member 31 is the first surface 31S, and the surface of the second light-transmitting member 35 opposite to the first surface 31S is the second surface 35S. This wafer is diced into individual pieces to obtain the light-transmitting members 30. The width of the light-transmitting member 30 is larger than the width of the opening surrounded by the second resin 62. The first light-transmitting member 31 is made of, for example, Al ｘ Ga １－ｘThe second light-transmitting member 35 may be, for example, sapphire or glass. When the second light-transmitting member 35 is sapphire, the first light-transmitting member 31 may be formed by growing a nitride semiconductor on the sapphire by chemical vapor deposition or physical vapor deposition. The nitride semiconductor is preferably undoped, which can reduce light absorption by impurities. Note that "undoped" refers to a material not intentionally doped with impurities. Alternatively, the impurity concentration may be below the detection limit of secondary ion mass spectrometry. The sapphire may have a second structure 36 including multiple second protrusions 361 formed of a PSS pattern on the surface on which the nitride semiconductor is grown. In this case, there is a flat portion between adjacent second protrusions 361. The plurality of second convex portions 361 are filled with the nitride semiconductor to form the first structure 32 including the plurality of first concave portions 322. The interface between the first structure 32 and the second structure 36 includes a plurality of prism surfaces 40. The prism surfaces 40 are specifically the interfaces between the first concave portions 322 and the second convex portions 361.

[0061] (Polishing Process) The process of preparing the light-transmissive member 30 may further include a process of polishing the light-transmissive member 30. For example, the second light-transmissive member 35 is mechanically polished and then chemically mechanically polished to flatten the light extraction surface (i.e., the second surface 35S) of the second light-transmissive member 35. For example, the surface is flattened to an arithmetic mean roughness Ra of 1 nm to 200 nm, preferably 1 nm to 150 nm, and more preferably 1 nm to 100 nm. This is smaller than the height of the second structural portion 36. This improves handling in processes after fabrication of the light-emitting device 1A.

[0062] (Step of Arranging the Light-Transmissive Member 30) In this step, the light-transmissive member 30 is arranged on the light-emitting unit 100A. Specifically, as shown in FIG. 9B , the light-transmissive member 30 is arranged so that the first surface 31S of the light-transmissive member 30 overlaps the upper surface 62S of the second resin 62. This allows the formation of a gap 22, which is a space surrounded by the light-transmissive member 30, the wavelength conversion member 20, and the second resin 62. Then, the side surfaces of the light-transmissive member 30 and the upper surface 62S of the second resin 62 are covered with a third resin 63. Finally, the light-emitting unit 100A, the light-transmissive member 30, and the third resin 63 are heat-treated at a predetermined temperature to harden the first resin 61, the second resin 62, and the third resin 63. This bonds the light-transmissive member 30 to the second resin 62 of the light-emitting unit 100A, thereby forming the light-emitting device 1A shown in FIG. 1A .

[0063] (Process for Forming Third Structure 50) As described in the second embodiment, the first light-transmissive member 31 may include the third structure 50. The third structure 50 shown in FIG. 2B may be provided, for example, in the process of preparing the light-transmissive member 30. A method for forming the third structure 50 will be described with reference to FIGS. 10A and 10B. First, as shown in FIG. 10A, a mask 70 having a predetermined pattern is formed on the first light-transmissive member 31. The mask 70 can be patterned by electron beam lithography or nanoimprinting. Among the patterned masks 70, the distance between the centers of adjacent masks 70 is at least smaller than the wavelength in air of the light emitted from the wavelength conversion member 20. Electron beam lithography and nanoimprinting are suitable for such fine processing. The mask 70 may be a single type of mask 70, or two or more types of masks 70 may be stacked, as long as the required selectivity is obtained in the subsequent etching. Next, as shown in Fig. 10B, the surface of the first light-transmissive member 31 is dry-etched using this mask 70. This forms a plurality of third recesses 502 extending from the first surface 31S toward the prism surface 40. Finally, as shown in Fig. 10C, the mask 70 is removed to form the third structural unit 50 having a plurality of third recesses 502. After the third structural unit 50 is formed, the first light-transmissive member 31 is disposed on the upper surface 62S of the second resin 62, thereby forming the light-emitting device 1B.

[0064] The third recess 502 is easier to form than the third convex portion 501, so forming the third recess 502 is preferable from the perspective of ease of manufacturing. On the other hand, the third convex portion 501 has a higher refractive index than air and has a high light confinement effect. Therefore, when the width of the third convex portion 501 changes in the first direction or the second direction, light is more sensitive to changes in refractive index, and the first recess 301 is more likely to impart a phase difference to light than the third concave portion 502. Therefore, the third convex portion 501 may be formed in the same manner as the third recess 502. By making the height of the third convex portion 501 smaller than the difference in height between the upper surface 62S of the second resin 62 and the upper surface 20S of the wavelength conversion member, i.e., the height of the gap 22, the possibility of the third convex portion 501 being damaged before and after bonding can be reduced.

[0065] 3, the third structure 50 may have a first region 51 and a second region 52. In this case, the mask 70 includes a plurality of first patterns and a plurality of second patterns. The first pattern is a pattern including a region where the width of the third convex portion 501 or the third concave portion 502 monotonically increases and a region where it monotonically decreases in a first direction. The second pattern is a pattern including a region where the width of the third convex portion 501 or the third concave portion 502 monotonically increases and a region where it monotonically decreases in a second direction different from the first direction. By dry etching the first light-transmitting member 31 through these patterns, the third structure 50 including a plurality of third convex portions 501 or third concave portions 502 is obtained.

[0066] The same applies to the third region 53 and the fourth region 54 described in FIG. 7 . That is, the first light-transmissive member 31 may be dry-etched using a mask 70 that includes not only the first pattern and the second pattern but also the third pattern and the fourth pattern. The third pattern is a pattern that includes a region in which the width of the third convex portion 501 or the third concave portion 502 monotonically increases and a region in which the width of the third convex portion 501 or the third concave portion 502 monotonically decreases in a third direction that is different from the first direction and the second direction. The fourth pattern is a pattern that includes a region in which the width of the third convex portion 501 or the third concave portion 502 monotonically increases and ... decreases in a fourth direction that is different from the first direction, the second direction, and the third direction.

[0067] (Variation 1) Figure 11 is a schematic cross-sectional view showing a light emitting device 1C of Variation 1. The light emitting device 1C of Variation 1 differs from the light emitting device 1A of Embodiment 1 in that the width of the light-transmitting member 30 is smaller than the width of the wavelength conversion member, and the upper surface 62S of the second resin 62 overlaps only with the lower surface 63S of the third resin 63. The light emitting device 1C also provides a light emitting device with a narrow light distribution. In a plan view, the wavelength conversion member 20 overlaps the light-transmitting member 30 and the third resin 63.

[0068] 12 is a schematic cross-sectional view showing a light emitting device 1D of Modification 2. The light emitting device 1D of Modification 2 differs from the light emitting device 1A of Embodiment 1 in that a lower surface 63S of the third resin 63 overlaps with the first resin 61 and the wavelength conversion member 20, and the gap 22 is formed by the light-transmitting member 30, the wavelength conversion member 20, and the third resin 63. The second resin 62 is not provided. The light emitting device 1D also provides a light emitting device with a narrow light distribution.

[0069] (Variation 3) FIG. 13 is a schematic cross-sectional view showing a light emitting device 1E of Variation 3. The light emitting device 1E of Variation 3 differs from the light emitting device 1D of Variation 2 in that the wavelength conversion member 20 has a convex portion facing the light-transmitting member 30 side. The first resin 61 is arranged to cover the side surface of the convex portion of the wavelength conversion member 20. This reduces the area of ​​the upper surface 20S of the wavelength conversion member 20 compared to before the convex portion was formed, thereby improving brightness. The width of the light-transmitting member 30 is at least smaller than the maximum width of the wavelength conversion member 20. In a planar view, the light-transmitting member 30 overlaps with at least the convex portion of the wavelength conversion member 20. This provides an even narrower light distribution and improves the brightness of the light extracted from the light-transmitting member.

[0070] 14A and 14B are diagrams illustrating an example of a portion surrounded by a dashed line in light emitting device 1E of Modification 3. As shown in Fig. 14A and 14B, side surface 63S1 of third resin 63 and side surface 20S1 of the convex portion of wavelength conversion member 20 do not necessarily have to be flush with each other.

[0071] 14A , the side surface 63S1 of the third resin 63 may be positioned outward of the side surface 20S1 of the wavelength conversion member 20. In this case, the width of the light-transmitting member 30 is smaller than the maximum width of the wavelength conversion member 20 and larger than the width of the convex portion of the wavelength conversion member 20. This allows light reflected by the prism surface 40 toward the wavelength conversion member 20 to be reflected by the upper surface 61S of the first resin 61 and the side surface 63S1 of the third resin 63 toward the light-transmitting member 30, improving the light extraction efficiency.

[0072] 14B , a side surface 63S1 of the third resin 63 may be disposed more inward than a side surface 20S1 of the wavelength conversion member 20. In this case, the width of the light-transmissive member 30 is smaller than the width of the convex portion of the wavelength conversion member 20.

[0073] In the first to third modifications, the third structural portion 50 as described in the second embodiment may be further provided on the first light-transmissive member 31. This makes it possible to obtain an even narrower light distribution.

[0074] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0075] Example 1 In Example 1, the light-emitting device shown in Fig. 1A was fabricated. The light-transmissive member 30 was obtained by growing a first light-transmissive member 31 made of gallium nitride on a second light-transmissive member 35 made of a sapphire substrate having a plurality of second convex portions. A prism surface 40 made of a plurality of first concave portions 322 and a plurality of second convex portions 361 was formed at the interface between the first light-transmissive member 31 and the second light-transmissive member 35. The second convex portions 361 formed a triangular lattice in plan view, and the spacing between the second convex portions 361 was 3.2 µm.

[0076] Example 2 In Example 2, the light-emitting device shown in FIG. 2A was fabricated. The light-emitting device has a third structure 50 including a plurality of third recesses 502, which differs from the light-emitting device of Example 1. In this example, the spacing a between the unit cells uc was set to 160 nm. The depth h2 of the third recesses 502 was set to 1200 nm. The length of the monotonically decreasing portion of the width of the third recesses 502 and the length of the monotonically increasing portion were set to 590 nm.

[0077] 15 was fabricated. This light emitting device differs from the light emitting device of Example 1 in that it does not have the light-transmitting member 30, the second resin 62, and the third resin 63.

[0078] <Evaluation> (Light Distribution Characteristics) The light distribution characteristics (i.e., far-field characteristics) of the light-emitting devices of Examples 1 and 2 and the Comparative Example were measured using an integrating sphere. When viewed in a plan view, the longitudinal direction of the light extraction surface is referred to as the 0° direction and the lateral direction as the 90° direction, and the full angle at half maximum was calculated for each of the 0° and 90° directions from the obtained light distribution characteristics. The full angle at half maximum of the light-emitting device of Comparative Example 1 was 121.9° in both the 0° and 90° directions. The full angle at half maximum of the light-emitting device of Example 1 was 94.3° in the 0° direction and 94.5° in the 90° direction. The full angle at half maximum of the light-emitting device of Example 2 was 92.8° in the 0° direction and 93.1° in the 90° direction. It was confirmed that the light-emitting devices of Examples 1 and 2 had a narrower light distribution than the light-emitting device of Comparative Example 1. (Maximum Brightness) The brightness of the light-emitting devices of Examples 1 and 2 and the Comparative Example was compared. The forward current was 1000 mA. The luminance was compared in an area defined by a square with sides of 1.2 mm relative to the light extraction surface. The maximum luminance of the light-emitting device of Example 1 was about 1.01 times that of Comparative Example 1. The maximum luminance of the light-emitting device of Example 2 was about 1.13 times that of Comparative Example 1. It was presumed that one of the factors for the improved maximum luminance of the light-emitting device of Example 2 was that the full angle at half maximum was smaller than that of the light-emitting device of Example 1.

[0079] The present invention includes the following disclosure: (Item 1) A light-emitting device comprising: a light-emitting element; a wavelength conversion member disposed on the light-emitting element; and a light-transmitting member disposed on the wavelength conversion member and having a first surface facing the wavelength conversion member and a second surface opposite the first surface, wherein the light-transmitting member comprises: a first light-transmitting member having a first refractive index and the first surface; and a second light-transmitting member having a second refractive index smaller than the first refractive index and the second surface, wherein the first light-transmitting member has a first structural portion including a plurality of first convex portions or a plurality of first concave portions on the side opposite the first surface (31S), the second light-transmitting member has a second structural portion including a plurality of second convex portions or a plurality of second concave portions on the side opposite the second surface, the interface between the first structural portion and the second structural portion includes a plurality of prism surfaces, and the arithmetic mean roughness Ra of the second surface is smaller than the height of the second structural portion. (Item 2) The first light-transmitting member is Al ｘ Ga １－ｘItem 1. The light emitting device according to Item 1, wherein x is N (0≦x≦1), and the second light-transmissive member is sapphire. (Item 3) The light emitting device according to Item 1 or 2, wherein the second light-transmissive member is PSS, and the second structure includes a plurality of the second convex portions formed by the PSS pattern. (Item 4) The light emitting device according to any one of Items 1 to 3, wherein, in a cross section viewed perpendicular to the second surface, the maximum thickness of the first light-transmissive member is 2 μm or more and 7 μm or less. (Item 5) The light emitting device according to any one of Items 1 to 4, wherein, in a cross section viewed perpendicular to the second surface, the maximum thickness of the second light-transmissive member is 100 μm or more and 300 μm or less. (Item 6) The light emitting device according to any one of Items 1 to 5, wherein the first light-transmissive member has a third structure including a plurality of third convex portions extending from the first surface toward the wavelength converting member or a plurality of third concave portions from the first surface toward the prism surface, and wherein the center-to-center distance between adjacent third convex portions and the center-to-center distance between adjacent third concave portions is at least equal to or less than the wavelength in air of light emitted from the wavelength converting member. (Item 7) The light emitting device according to Item 6, wherein the third structure has a plurality of first regions and a plurality of second regions in a planar view, and the third structure in the first region has a plurality of regions where the widths of adjacent third convex portions or third concave portions monotonically increase and monotonically decrease in a first direction, and the third structure in the second region has a plurality of regions where the widths of adjacent third convex portions or third concave portions monotonically increase and monotonically decrease in a second direction different from the first direction. (Item 8) The light emitting device according to any one of Items 1 to 7, wherein the light emitting element is a nitride semiconductor light emitting element, and the wavelength conversion member is ceramic containing a YAG phosphor. (Item 9) The light emitting device according to any one of Items 1 to 8, further comprising a first resin covering a side surface of the light emitting element and a side surface of the wavelength conversion member, and a second resin disposed on the first resin, wherein an upper surface of the second resin is positioned higher than an upper surface of the wavelength conversion member, and the translucent member is supported by an upper surface of the second resin.(Item 10) A method for manufacturing a light emitting device comprising: preparing a light emitting unit including a wiring board, a light emitting element connected to the wiring board, a wavelength converting member disposed on the light emitting element, a first resin covering a side surface of the light emitting element and a side surface of the wavelength converting member, and a second resin disposed on the first resin and having an upper surface at a position higher than an upper surface of the wavelength converting member; preparing a light-transmitting member having a first surface and a second surface opposite to the first surface; and disposing the light-transmitting member on an upper surface of the second resin, wherein the light-transmitting member comprises: a first light-transmitting member having a first refractive index and having the first surface disposed on the upper surface of the first resin; and a second light-transmitting member having a second refractive index smaller than the first refractive index and having the second surface, wherein the first light-transmitting member has a first structural portion on the opposite side to the first surface, the first structural portion including a plurality of first convex portions or a plurality of first concave portions, and the second light-transmitting member has a second structural portion on the opposite side to the second surface, Item 11. A method for manufacturing a light-emitting device, wherein an interface between the first structure and the second structure includes a plurality of prism surfaces, and an arithmetic mean roughness Ra of the second surface is smaller than a height of the second structure. (Item 11) The method for manufacturing a light-emitting device according to Item 10, wherein the step of preparing the light-transmitting member further includes dry-etching a surface of the first light-transmitting member to form a third structure including a plurality of third convex portions extending from the first surface toward the wavelength conversion member or a plurality of third concave portions extending from the first surface toward the prism surface, wherein the center-to-center distance between adjacent third convex portions and the center-to-center distance between adjacent third concave portions are smaller than at least the wavelength in air of light emitted from the wavelength conversion member, and

[0080] 1A Light emitting device 1B Light emitting device 10 Light emitting element 11 Substrate 12 Semiconductor laminate 13 First electrode 131 First wiring 14 Second electrode 141 Second wiring 20 Wavelength conversion member 20S Upper surface 20S1 Side surface 21 Adhesive 22 Gap 30 Light-transmitting member 30S Side surface 31 First light-transmitting member 31S First surface 32 First structural portion 321 First convex portion 322 First concave portion 35 Second light-transmitting member 35S Second surface 36 Second structural portion 361 Second convex portion 362 Second concave portion 40 Prism surface 41S Flat surface 50 Third structural portion 501 Third convex portion 502 Third concave portion 502S Flat surface 51 First region 52 Second region 53 Third region 54 Fourth region 60 Wiring board 61 First resin 61S Upper surface 62 Second resin 62S Upper surface 63 Third resin 63S Lower surface 63S1 Side surface 70 Mask 100A Light-emitting portion

Claims

1. A light-emitting device comprising: a light-emitting element; a wavelength conversion member disposed on the light-emitting element; and a light-transmitting member disposed on the wavelength conversion member and having a first surface facing the wavelength conversion member and a second surface on the side opposite to the first surface, wherein the light-transmitting member includes a first light-transmitting member having a refractive index of a first refractive index and the first surface, and a second light-transmitting member having a refractive index of a second refractive index smaller than the first refractive index and the second surface, the first light-transmitting member has a first structure portion including a plurality of first convex portions or a plurality of first concave portions on the side opposite to the first surface, the second light-transmitting member has a second structure portion including a plurality of second convex portions or a plurality of second concave portions on the side opposite to the second surface, an interface between the first structure portion and the second structure portion includes a plurality of prism surfaces, and an arithmetic mean roughness Ra of the second surface is smaller than a height of the second structure portion.

2. The first light-transmissive member is Al ｘ Ga １－ｘ N (0 ≦ x ≦ 1), and the second light-transmissive member is sapphire. The light-emitting device according to claim 1.

3. The light-emitting device according to claim 2, wherein the second light-transmitting member is a PSS, and the second structure portion includes the plurality of second convex portions formed from a pattern of the PSS.

4. The light-emitting device according to any one of claims 1 to 3, wherein in a cross-sectional view perpendicular to the second surface, a maximum value of a thickness of the first light-transmitting member is 2 µm or more and 7 µm or less.

5. The light-emitting device according to any one of claims 1 to 3, wherein in a cross-sectional view perpendicular to the second surface, a maximum value of a thickness of the second light-transmitting member is 100 µm or more and 300 µm or less.

6. The light-emitting device according to any one of claims 1 to 3, wherein the first light-transmitting member has a third structure portion including a plurality of third convex portions extending from the first surface toward the wavelength conversion member or a plurality of third concave portions from the first surface toward the prism surface, and a center-to-center distance between adjacent ones of the third convex portions and a center-to-center distance between adjacent ones of the third concave portions are each equal to or less than a length of a wavelength of light emitted from the wavelength conversion member in air.

7. In a plan view, the third structure portion has a plurality of first regions and a plurality of second regions. In the first region of the third structure portion, there are a plurality of regions where the width of adjacent third convex portions or third concave portions monotonically increases and regions where the width monotonically decreases in a first direction. In the second region of the third structure portion, there are a plurality of regions where the width of adjacent third convex portions or third concave portions monotonically increases and regions where the width monotonically decreases in a second direction different from the first direction. The light-emitting device according to claim 6.

8. The light-emitting element is a nitride semiconductor light-emitting element, and the wavelength conversion member is a ceramic containing a YAG phosphor. The light-emitting device according to any one of claims 1 to 3.

9. Further comprising a first resin covering a side surface of the light-emitting element and a side surface of the wavelength conversion member, and a second resin disposed on the first resin. An upper surface of the second resin is positioned higher than an upper surface of the wavelength conversion member, and the light-transmitting member is supported by the upper surface of the second resin. The light-emitting device according to any one of claims 1 to 3.

10. Preparing a wiring board, a light-emitting element connected to the wiring board, a wavelength conversion member disposed on the light-emitting element, a first resin covering side surfaces of the light-emitting element and the wavelength conversion member, and a light-emitting portion including a second resin disposed on the first resin and having an upper surface positioned higher than an upper surface of the wavelength conversion member; preparing a light-transmitting member having a first surface and a second surface on the opposite side of the first surface; and disposing the light-transmitting member on the upper surface of the second resin. The light-transmitting member has a first light-transmitting member having a first refractive index and having the first surface disposed on the upper surface of the first resin, and a second light-transmitting member having a second refractive index smaller than the first refractive index and having the second surface. The first light-transmitting member has a first structure portion including a plurality of first convex portions or a plurality of first concave portions on the side opposite to the first surface. The second light-transmitting member has a second structure portion including a plurality of second convex portions or a plurality of second concave portions on the side opposite to the second surface. An interface between the first structure portion and the second structure portion includes a plurality of prism surfaces, and an arithmetic mean roughness Ra of the second surface is smaller than a height of the second structure portion. A method for manufacturing a light-emitting device.

11. The step of preparing the light-transmissive member further includes forming a third structure portion including a plurality of third convex portions extending from the first surface toward the wavelength conversion member or a plurality of third concave portions from the first surface toward the prism surface by dry-etching the surface of the first light-transmissive member. The center-to-center distance between adjacent third convex portions and the center-to-center distance between adjacent third concave portions are each smaller than at least the length of the wavelength of the light emitted from the wavelength conversion member in air. After forming the third structure portion, the first light-transmissive member is disposed on the upper surface of the second resin. A method of manufacturing a light-emitting device according to claim 10.

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