Optical semiconductor equipment

Abstract

To provide an optical semiconductor device capable of sufficiently reducing light on a side closer to a short wavelength than a specific wavelength while suppressing attenuation of output of light on a side closer to a long wavelength than the specific wavelength.SOLUTION: An optical semiconductor device 100 includes: a package substrate 1; a light emitting element 2 arranged on an upper surface of the package substrate 1 so that an emission surface 21 which is a surface on a light extraction side becomes an upper surface; a transparent lid 3 which forms a closed space S with the package substrate 1 and covers the light emitting element 2; and a filter 4 which is arranged on an upper surface side of the light emitting element 2 and has a transmittance of a specific wavelength of 50%. The filter 4 is formed in an upwardly convex shape, and a surface forming a top part includes a central part of the emission surface 21 in a top view.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] This invention relates to an optoelectronic device. [Background technology]

[0002] For various therapeutic purposes, ultraviolet light sources with wavelengths of 300-340 nm are sometimes used. Traditionally, mercury lamps and excimer lights have been used as such light sources.

[0003] In recent years, there has been a growing demand to replace mercury lamps and excimer lights, which are light sources with wavelengths of 300-340 nm, with ultraviolet LEDs.

[0004] Patent Document 1 describes an ultraviolet light-emitting device as an optical semiconductor element comprising an optical semiconductor chip enclosed in a package. This ultraviolet light-emitting device consists of an ultraviolet light-emitting chip placed on a metal base (package), a substantially cylindrical metal cap (package) bonded to the metal base and positioned to surround the sides of the ultraviolet light-emitting chip, a glass window (package) sealing the opening of the metal cap, and leads that penetrate the metal base while being insulated by an insulating material and connected to the ultraviolet light-emitting chip via conductive wires. An ultraviolet transmission filter film, which is an optically functional film, is formed on the outer surface of the glass window by vacuum deposition. This film is constructed by laminating a low refractive index film such as silicon dioxide and a high refractive index film such as hafnium dioxide, and is configured to cut visible light and infrared rays and transmit only ultraviolet light. Light emitted from the ultraviolet light-emitting chip passes through this ultraviolet transmission filter film, cutting off visible light and infrared rays before being emitted to the outside. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2007-158006 [Overview of the project] [Problems that the invention aims to solve]

[0006] Compared to the emission spectra of mercury lamps and excimer lights, the full width at half maximum (FWHM) of the emission spectrum of ultraviolet LEDs is wider. For example, if the peak wavelength, which is the wavelength at which ultraviolet LEDs have maximum intensity, is 308 nm, the emission intensity below 300 nm for excimer lights (wavelength 308 nm, XeCl) is about 10% of the emission intensity at the peak wavelength, whereas for ultraviolet LEDs, the emission intensity below 300 nm is about 30% of the emission intensity at the peak wavelength. In other words, the emission intensity below 300 nm tends to be stronger than that of excimer lights. Since light below 300 nm can have adverse effects on the human body, it is necessary to cut out the short wavelength range below 300 nm when replacing them with ultraviolet LEDs.

[0007] Furthermore, mercury lamps and excimer lights are linear light sources with a straight tube shape, and their structure radiates light uniformly perpendicular to the surface of the tube. Therefore, to cut wavelengths below a specific wavelength, a single light cut filter could be placed in the direction of light emission from the tube. However, LED chips are point light sources, and the direction of light emitted from an LED chip is omnidirectional. As a result, the light distribution of optoelectronic devices with flat emission surfaces, such as SMDs that contain LED chips, is wide, and light may be emitted over an angular range of approximately ±60° from the vertical.

[0008] High-pass filters, which cut out wavelengths below a specific wavelength, include filters that utilize optical coherence using dielectric thin films, either single-layer or multi-layer, and filters that, unlike those that utilize optical coherence, utilize absorption phenomena caused by the material. Filters that utilize optical coherence (hereinafter sometimes referred to as optical interference filters) can reduce the wavelength difference between the wavelength at which transmittance is 90% and the wavelength at which transmittance is 10%, making them effective when it is desired to cut out wavelengths shorter than a specific wavelength in the wavelength profile of an LED chip while increasing the light output on the wavelength side longer than that specific wavelength. However, optical interference filters have the problem that the optical path length within the filter changes depending on the angle of incidence of light, so depending on the observation angle (angle of incidence), wavelengths below a specific wavelength may not be effectively cut out.

[0009] Therefore, there is a need for an optoelectronic device that incorporates a point light source, such as an LED chip, that can sufficiently reduce light on wavelengths shorter than a specific wavelength while suppressing the attenuation of light on wavelengths longer than a specific wavelength.

[0010] This invention has been made in view of the above circumstances, and its objective is to provide an optical semiconductor device that can sufficiently reduce light on wavelengths shorter than a specific wavelength while suppressing the attenuation of the output of light on wavelengths longer than a specific wavelength. [Means for solving the problem]

[0011] To achieve the above objective, the optical semiconductor device according to the present invention is: Package substrate and A light-emitting element is arranged on the upper surface of the package substrate such that the light-extracting side, which is the light extraction side, is the upper surface. A closed space is formed between the package substrate and the transparent cover that covers the light-emitting element, The transparent lid is provided with an optical interference filter having a transmittance of 50% at a specific wavelength on its surface. The aforementioned filter is It has a convex shape that points upwards. The surface forming the top of the convex shape includes the central portion of the light emitting surface in a vertical direction view.

Advantages of the Invention

[0012] It is possible to provide an optical semiconductor device capable of sufficiently reducing light on the shorter wavelength side than a specific wavelength while suppressing attenuation of the output of light on the longer wavelength side than the specific wavelength.

Brief Description of the Drawings

[0013] [Figure 1A] It is a top view of an optical semiconductor device according to a first embodiment. [Figure 1B] It is a modified example of the top view of an optical semiconductor device according to a first embodiment. [Figure 2] It is a cross-sectional view of an optical semiconductor device according to a first embodiment. [Figure 3] It is a graph showing an example of the transmission spectrum of a filter. [Figure 4A] It is a diagram showing the emission spectrum in an example. [Figure 4B] It is the light distribution characteristic of wavelengths longer than λ1 in an example. [Figure 4C] It is the light distribution characteristic of wavelengths of λ1 or less in an example. [Figure 5A] It is a diagram showing the emission spectrum in a comparative example. [Figure 5B] It is the light distribution characteristic of wavelengths longer than λ1 in a comparative example. [Figure 5C] It is the light distribution characteristic of wavelengths of λ1 or less in a comparative example. [Figure 6] It is an explanatory diagram of a method for measuring the light distribution characteristic. [Figure 7] It is a cross-sectional view of an optical semiconductor device according to a second embodiment. [Figure 8] It is a cross-sectional view of an optical semiconductor device according to a modified example of a second embodiment. [Figure 9] It is a cross-sectional view of an optical semiconductor device according to a third embodiment.

Modes for Carrying Out the Invention

[0014] An optical semiconductor device according to an embodiment of the present invention will be described based on the drawings.

[0015] (First Embodiment) (Overview) Figures 1A and 1B show top views of the optical semiconductor device 100 according to this embodiment. Figure 2 shows a cross-section of the optical semiconductor device 100 (viewed along the line II-II in Figure 1A).

[0016] In the following, in the optoelectronic device 100 shown in Figure 2, the side of the transparent lid 3 viewed from the package substrate 1 will be referred to as the top, and the side of the transparent lid 3 viewed from the package substrate 1 will be referred to as the bottom. The upper surface will be referred to as the top surface, and the lower surface as the bottom surface. This will be used as the basis for explanations in Figures 2 and beyond, and in other embodiments. For example, the side of the transparent lid 3 that faces the light-emitting element will be referred to as the bottom surface 32, and the side of the transparent lid 3 opposite to the light-emitting element will be referred to as the top surface 31. Furthermore, the surface of the transparent lid 3 refers to both or either of the top surface 31 and the bottom surface 32 of the transparent lid 3.

[0017] In this embodiment, an up-and-down view refers to a view of the transparent lid 3 from above in the thickness direction of the central part P of the transparent lid 3, and means both a viewpoint from above looking at the upper surface 31 of the lid (referred to as a top view) and a viewpoint from below looking at the lower surface 32 of the lid (referred to as a bottom view). In this embodiment, "outside" refers to the side away from the central part P, and "inside" refers to the side towards the central part P. Similarly, "outer circumference" refers to the end on the side farther from the central part P, and "inner circumference" refers to the end on the side towards the central part P.

[0018] First, an overview of the optoelectronic semiconductor device 100 will be described. As shown in Figure 2, the optoelectronic semiconductor device 100 comprises a package substrate 1, a light-emitting element 2 positioned on the upper surface of the package substrate 1 with the light-extracting surface 21 facing upwards, a transparent cover 3 (see Figures 1A, 1B, and 2) that forms a closed space S between the package substrate 1 and the light-emitting element 2 and covers the light-emitting element 2, and an optical interference filter 4 positioned on the surface of the transparent cover 3 with a transmittance of 50% at a specific wavelength λ1. The filter 4 is a high-pass filter.

[0019] The filter 4 has a convex shape directed upwards toward the exit surface 21, and the surface forming the top (flat portion 4a in Figure 1A) includes the central portion P of the exit surface 21 when viewed in the vertical direction. More preferably, the surface forming the top includes the exit surface 21 when viewed in the vertical direction.

[0020] In this embodiment, the side view is a cross-section taken horizontally through the central part P of the light-emitting element to one side of the emission surface 21, as shown in Figure 2, which is the cross-section taken along the line II-II in Figure 1A, and is viewed from the direction perpendicular to the cross-section.

[0021] The filter 4 is preferably formed to be convex upward from the discharge surface 21, according to the shape of the transparent lid 3. The convex shape is progressively narrower upward from the discharge surface 21, and in a side view, the surface forming the apex of the convex shape is preferably a flat portion parallel to the discharge surface 21.

[0022] A convex shape is a shape in which the cross-sectional shape in side view is curved except for a part of a polygon or the surface forming the apex. For example, it may be a trapezoid, a polygon circumscribing a semiellipse (including a semicircle), or a semiellipse with a flat portion at the apex. In particular, a semiellipse with a flat portion at the apex in side view preferably has a shape that maintains a constant distance from the exit surface 21.

[0023] Furthermore, as shown in Figure 2, when the filter 4 is viewed from the side, it is preferable that the surfaces other than the top (inclined portion 4 and inclined portion 4c in Figure 2) are formed on surfaces whose normals are any inclination angle in the range of 0° < θ ≤ 90°, when the angle of a light ray that is obliquely directed away from directly above the output surface 21 with respect to a perpendicular line from the outer circumference of the output surface 21 toward the transparent lid 3 is defined as the inclination angle θ.

[0024] In this embodiment, the filter 4 is disposed on the transparent lid 3 so as to conform to the surface of the upper surface 31 of the transparent lid 3. That is, in this embodiment, the filter 4 is shaped to conform to the shape of the surface of the upper surface 31 of the lid.

[0025] In the optoelectronic device 100, light emitted from the emission surface 21 of the light-emitting element 2 is radiated to the outside through the transparent cover 3. At this time, the light emitted from the emission surface 21 passes through the filter 4, and light with wavelengths shorter than λ1 is cut off.

[0026] The optoelectronic device 100 can cut off light with wavelengths shorter than λ1 while suppressing the attenuation of the output of light with wavelengths longer than λ1, which is a specific wavelength.

[0027] (Explanation of each part) The following describes the details of each part of the optoelectronic device 100. As shown in Figure 2, the optoelectronic device 100 comprises a package substrate 1, a light-emitting element 2, a transparent cover 3, and an optical interference filter 4 arranged on the surface of the transparent cover 3, as described above. As shown in Figure 2, the optoelectronic device 100 is symmetrical in the cross-section taken along the line II-II in Figure 1A, for example. In addition, the optoelectronic device 100 includes electrodes and other components that are not shown.

[0028] As shown in Figure 2, the angle of the optical path of a light ray emitted diagonally away from the top of the emission surface 21, starting from the outer circumference of the emission surface 21, with respect to the perpendicular from the outer circumference of the emission surface 21 to the transparent cover 3 is defined as the inclination angle θ. In Figure 2, the virtual lines of emitted light corresponding to inclination angles θ of 0°, 10°, 20°, 30°, 40°, and 50° are θ0, θ2, and θ3, respectively. 10、 θ 20 , θ 30、 θ 40、 θ 50、 It is indicated by the symbol.

[0029] The light-emitting element 2 shown in Figure 2 is, for example, an LED chip. The LED chip can be selected according to the required wavelength range. Preferably, the light-emitting element 2 is an ultraviolet LED. The light-emitting element 2 has, for example, a emission center wavelength between 300 nm and 350 nm, and the explanation will be given using the case where the emission center wavelength is 310 nm as an example. The emission surface 21 of the light-emitting element 2 is formed in a planar shape. The shape of the emission surface 21 in a top view can be any shape, such as a square, rectangle, polygon, or circle, depending on the application, function, or manufacturing convenience of the optoelectronic device 100. In this embodiment, as an example, the case in which the light-emitting element 2 is square in a top view is shown (see Figures 1A and 1B).

[0030] As shown in Figure 2, the package substrate 1 is the part that serves as the base on which the light-emitting element 2 is mounted and fixed. The package substrate 1 can be any material suitable for mounting the light-emitting element 2, but it is particularly preferable that it has heat dissipation properties. Examples of materials suitable for forming the package substrate 1 include ceramics such as AlN, Al-SiC, and Mg-SiC, and metals such as Al, Mo, Cu, Cu-W, Cu-Mo, and Kovar. The material used to form the package substrate 1 is preferably a fired AlN body.

[0031] The package substrate 1 may be formed in a shape such as a flat plate or a shape with a recess. Figure 2 shows an example of a package substrate 1 with a recess, where it is formed in a bottomed cylindrical shape and its cross-section is an angular U-shape. The bottom surface 11 inside the cylinder of the package substrate 1 (the top surface of the package substrate 1) is formed in a flat shape. The light-emitting element 2 is placed on the bottom surface 11 with the light-extracting surface 21, which is the side that extracts light, facing upwards. A transparent lid 3, which will be described later, is placed on the upper end of the cylindrical portion 13 of the package substrate 1.

[0032] The transparent lid 3 is made of a material that transmits light from the light-emitting element 2. Examples of materials used to form the transparent lid 3 include glass (soda-lime glass), quartz, and metal oxide crystals such as sapphire. Preferably, the transparent lid 3 is made of synthetic quartz (refractive index: 1.49), fused quartz (refractive index: 1.49), or sapphire (refractive index: 1.80).

[0033] The transparent lid 3 is formed in a convex shape that points upward, and the surface forming the apex of the convex portion includes the central part P of the exit surface 21 when viewed in the vertical direction. When viewed from the side, the surface forming the apex of the convex shape is a flat portion parallel to the exit surface 21. For example, in this embodiment, both the upper surface 31 and the lower surface 32 of the lid are formed in a convex shape that points upward by combining flat surfaces with different normal directions. As shown in other embodiments described later, either the upper surface 31 or the lower surface 32 of the lid may have a convex portion that is formed in a convex shape that points upward. The convex shape is a shape that gradually narrows towards the top. The shape of the convex portion of the transparent lid 3 may be, for example, a trapezoid, a polygon with a semi-ellipse circumscribing it, or a semi-ellipse with a flat portion at the top when viewed from the side. In a side view, when the transparent lid 3 is viewed from the side, it is preferable that the surfaces other than the top (inclined portions 31b and 31c, inclined portions 32b and 32c in Figure 2) are formed with a normal to any inclination angle in the range of 0° < θ ≤ 90°, where the angle of a light ray that is obliquely directed away from directly above the exit surface 21 is defined as the inclination angle θ.

[0034] The shape of the convex portion of the transparent lid 3 may be part of a convex polyhedron. Because it has a shape that gradually narrows upwards, the position of the mountain fold line of the slope of the convex portion of the transparent lid 3 becomes upwards as it approaches the central part P. A convex polyhedron is a type of polyhedron in which the dihedral angles (angles formed by two adjacent faces) at all edges are less than 180° and there are no self-intersections. Specifically, this includes regular polyhedra, semi-regular polyhedra, Catalan solids, Johnson solids, delta polyhedra, zonal polyhedra, and truncated cubes, but prisms, antiprisms, and stellated regular polyhedra are not included. It also includes polyhedra composed of multiple faces with different face orientations (including equivalent faces), such as a polyhedron whose top flat face is hexagonal, has rectangular inclined faces on the edges of the hexagon, and has triangular inclined faces starting from the vertices of the hexagon.

[0035] Figure 2 shows a case where the transparent lid 3 has a flat surface as the top of a convex shape on its upper surface 31. In a side view, the upper flat portion 31a is parallel to the ejection surface 21. In a side view, the bottom portion 32a is also parallel to the ejection surface 21.

[0036] As an example of the shape of the lid top surface 31 in the case of Figure 1A, it is shown that the cross-sectional shape in side view is part of a polygon, and an upper planar portion 31a is formed parallel to the exit surface 21 as a planar top. Figure 1B shows the case in which the corner that becomes a mountain fold in Figure 1A has a radius of curvature equal to the distance from the exit surface 21 when the exit surface 21 is projected onto the same plane in a vertical view. Note that in Figures 1A, 1B, and 2, the slopes located outside the upper planar portion 31a are shown as inclined surface portion 31b and inclined surface portion 31c.

[0037] The transparent lid 3 forms a closed space S between itself and the package substrate 1 and is positioned to cover the light-emitting element 2 from above. When viewed in the vertical direction, the upper flat portion 31a of the transparent lid 3 includes at least the central portion P of the emission surface 21, and preferably the upper flat portion 31a encloses the emission surface 21. In Figure 2, when viewed from above, the upper flat portion 31a is positioned to completely cover the emission surface 21 of the light-emitting element 2. That is, in the region of the transparent lid 3 that overlaps with the light-emitting element 2 when viewed from above, there is an upper flat portion 31a that is planar and parallel to the emission surface 21 of the light-emitting element 2. The light-emitting element 2 is sealed in the closed space S with its position between the bottom surface 11 of the package substrate 1 and the transparent lid 3 when viewed in the vertical direction.

[0038] The shape of the package substrate 1 may be a shape with a recess or a plate shape. The shape of the package substrate 1 and the shape of the transparent lid 3 shown in this embodiment and other embodiments should be such that at least one of them has a recess and can form a closed space S.

[0039] As will be described later, a filter 4 is placed on the surface of the transparent lid 3, but the surface roughness of the transparent lid 3 is arbitrary as long as it does not interfere with the placement of the filter 4. In this embodiment, as will be described later, the filter 4 is placed and fixed on the upper surface of the transparent lid 3, that is, on the surface of the lid upper surface 31.

[0040] The transparent lid 3 is joined to the package substrate 1, for example, via an adhesive layer 9. The adhesive layer 9 may be formed from a bonding material. The selection of the bonding material and the method of forming the adhesive layer 9 are arbitrary, but for example, metal layers may be formed on the parts of the package substrate 1 and the transparent lid 3 to be joined, and then these metal layers may be pressed together, or various types of solder or resin-based adhesives may be used. The adhesive layer 9 is preferably AuSn solder.

[0041] Filter 4 is a light-cutting filter that utilizes optical coherence. It is preferable that filter 4 be placed over the entire surface area of ​​the transparent lid 3. Filter 4 includes a flat portion 4a and one or more inclined portions (e.g., inclined portion 4b, inclined portion 4c).

[0042] Filter 4 is a laminate of two or more dielectric layers with different refractive indices. In filter 4, it is preferable to repeatedly laminate two or more layers with different refractive indices, and the number of repetitions is preferably in the range of 3 pairs to 100 pairs. Within this range, the steepness of the transmittance near a specific wavelength λ1 can be improved by increasing the number of pairs or increasing the difference in refractive indices. As shown in Figure 3, filter 4 in this embodiment is a high-pass filter that sets the transmittance at a predetermined wavelength or shorter (short wavelength side) at a predetermined incident angle (e.g., 0°) to 50% or less. Figure 3 shows an example of the wavelength dependence (transmission spectrum) of the transmittance of filter 4 exemplified in this embodiment at 5° intervals in the range of incident angles from 0° to 60°. In Figure 3, the "filter transmittance" on the vertical axis is the transmittance of light from filter 4. The transmission spectrum of filter 4 shown in Figure 3 can be measured using a spectrophotometer (e.g., V-650 manufactured by JASCO Corporation). For this measurement, the optical interference filter may be formed on the transparent lid 3, or alternatively, on a quartz glass substrate or a sapphire substrate.

[0043] If filter 4 has two layers, for example, SiO2 (refractive index: 1.46) can be selected as the material for the first layer. For example, TiO2 (refractive index: 2.26), HfO2 (refractive index: 1.95), or Sc2O3 (refractive index: 1.96) can be selected as the material for the second layer. If filter 4 has three layers, for example, Al2O3 (n=1.71) or MgO (n=1.74) can be selected as the material for the third layer. If it consists of four or more layers, you can select from the example materials as appropriate.

[0044] The characteristics of filter 4, i.e., its transmission spectrum, can be determined by setting the material of the layers used, the thickness of each layer, and the number of pairs. In this embodiment, the case in which filter 4 has an SiO2 layer and a TiO2 layer will be described as an example. Table 1 shows the refractive index and film thickness data of each layer in the optical interference filter in Figure 3, which shows an example of the transmission spectrum of filter 4. The SiO2 film and TiO2 film can be deposited to their respective thicknesses by sputtering and formed within a predetermined range using photolithography and lift-off methods.

[0045] [Table 1]

[0046] In the following explanation, we will use the case where λ1 as a specific wavelength is 305 nm as an example. Filter 4, as an example, has a wavelength λ1 of 305 nm at which the transmittance is 50% at an incident angle of 0 degrees, and the transmittance below λ1 (on the shorter wavelength side) is 50% or less. Note that λ1 is set to reduce the light output in the wavelength range to be cut within the range between the emission center wavelength of the light-emitting element 2 (in this embodiment, we will explain the case where it is 310 nm as an example) and the maximum wavelength within the wavelength range to be cut (for example, 300 nm or more and 310 nm or less). If the light-emitting element 2 is an ultraviolet LED with an emission center wavelength of 300 nm or more and 350 nm or less, the full width at half maximum in its wavelength profile is about 4 to 8 nm on the shorter wavelength side of the emission center wavelength, so it is preferable that λ1 is a wavelength 3 to 10 nm shorter than the emission center wavelength. For example, λ1 is a wavelength in the ultraviolet region of 280 nm or more and 320 nm or less.

[0047] In the following, the incident angle at which the transmittance of filter 4, a high-pass filter, becomes 50% at a specific wavelength λ1 is referred to as the optimal angle α. The following explanation describes the case where filter 4 is a filter with angle dependence of filter transmittance as shown in Figure 3. In Figure 3, the angle at which the transmittance is 50% at a specific wavelength λ1 of 305 nm is 0°, and the optimal angle α = 0°. That is, in filter 4 shown in Figure 2, as the incident angle increases from 0°, which is equal to the optimal angle α, the wavelength range at which the transmittance is 50% or less shifts to the shorter wavelength side. The preferred range for the optimal angle α of filter 4 is 0° ≤ α ≤ 20°, and more preferably 0° ≤ α ≤ 5°.

[0048] Consider an optical interference filter having the transmittance characteristics shown in Figure 3, for example, when the top surface 31 of the transparent lid 3 is entirely horizontal to the emission surface 21. As the inclination angle θ from the outer circumference of the emission surface 21 increases, the incident angle to the filter provided on the top surface 31 of the transparent lid 3 increases, making it impossible to effectively cut out light in the wavelength band below λ1, and causing light in the wavelength band below λ1 to be radiated outside the optoelectronic device 100. In the range of angles θ greater than the optimal angle, the efficiency of the flat portion 4a of the filter 4 in cutting wavelengths shorter than λ1 decreases. For example, at an incident angle of 15°, the transmittance of the longest wavelength (e.g., 300nm) in the wavelength band to be cut is less than 10%, but at an incident angle of 20°, the transmittance of the longest wavelength (e.g., 300nm) in the wavelength band to be cut exceeds 50%, and at an incident angle of 25°, the transmittance of the longest wavelength (e.g., 300nm) in the wavelength band to be cut exceeds 90%.

[0049] Therefore, as shown in Figure 2, in this embodiment, the filter 4 has a flat portion 4a parallel to the emission surface 21 in a side view, and an inclined portion 4b having a normal that is inclined with respect to the normal of the emission surface 21. In Figure 2, the flat portion 4a of the filter covers the entire surface of the emission surface 21 in a vertical view. The flat portion 4a of the filter has a tilt angle θ = 0° and a normal θ aIt is configured as such. There may be one or more inclined portions, which have a normal line that is greatly inclined with respect to the normal line of the emission surface 21 as they move away from the flat portion 4a. The ones closer to the flat portion 4a can be named as 4b, 4c, 4d, etc. Assume there are N (N is a natural number) inclined portions. Whether the cross-sectional shape of the filter 4 in side view in the convex shape is trapezoidal, polygonal, or has a shape with a curve other than the surface forming the top can be obtained by arbitrarily increasing the N number. In this embodiment, the flat portion 4a of the filter 4 is disposed on the upper flat portion 31a of the lid upper surface 31 of the transparent lid 3 and becomes the top of the filter 4 in a state of surrounding the central portion of the emission surface 21 in the vertical direction view. The inclined portions 4b and 4c are disposed on the inclined surface portions 31b and 31c of the lid upper surface 31. As described above, each of the N inclined portions has a normal line with an inclination angle within the range of 0° < θ ≦ 90° in side view.

[0050] As a modification of the arrangement of the filter 4, the filter may be formed on the lid lower surface 32. In that case, the flat portion 4a of the filter 4 is disposed on the bottom surface portion 32a of the lid lower surface 32 of the transparent lid 3 and becomes the top of the filter 4 in a state of surrounding the central portion of the emission surface 21 in the vertical direction view. The inclined portions 4b and 4c are disposed on the inclined surface portions 32b and 32c of the lid lower surface 32.

[0051] By having the inclined portions 4b and 4c in this way, it is possible to efficiently cut the light with wavelengths shorter than λ1, which would pass through when incident on the transparent lid 3 without inclined portions at a large incident angle. In this embodiment, the boundary (ridge fold line) between the flat portion 4a and the inclined portion 4b is at a position where the inclination angle θ = 10°. The boundary between the flat portion 4a and the inclined portion 4b is preferably within the range of 0 ≦ θ ≦ 20° from the outer peripheral portion of the emission surface 21, and more preferably within the range of 0 ≦ θ ≦ 15°.

[0052] In side view, with respect to the perpendicular line from the outer periphery of the emission surface 21 toward the transparent lid 3, the inclination angle of the light ray obliquely directed to the inclined portion 4b (inclined surface portion 31b) is θ b Let it be. The inclined portion 4b in this embodiment is θ b = θ 20This is a surface whose normal is (inclination angle θ = 20°). This is the same inclination angle as the light ray that is the normal to the inclined surface portion 31b. θ b Preferably, this angle is greater than the inclination angle at the boundary between the flat portion 4a and the inclined portion 4b. This ensures that light from the emission surface 21 of the light-emitting element 2 is incident on the inclined portion 4b of the filter 4 at an incident angle that is close to perpendicular.

[0053] In a side view, the angle of inclination of the light rays that diagonally approach the inclined portion 4c (inclined surface portion 31c) is θ, relative to the perpendicular line from the outer circumference of the emission surface 21 toward the transparent lid 3. c In this embodiment, the inclined portion 4c is θ c =θ 40 This is a plane whose normal is (tilt angle θ = 40°). This is the same tilt angle as the light ray that is normal to the tilted surface portion 31c. As a result, light from the emission surface 21 of the light-emitting element 2 is incident on the tilted portion 4c of the filter 4 at an incident angle that is close to perpendicular.

[0054] In this embodiment, the boundary (mountain fold line) between the inclined portion 4b and the inclined portion 4c is at a position of θ = 30°. The range in which the inclined portion 4b is provided (range of the inclined surface portion 31b) is θ b -15°≦θ≦θ b It is preferable to keep it within the range of +15°, θ b -10°≦θ≦θ b It is more preferable to keep it within the range of +10°. Also, the boundary between the inclined portion 4b and the inclined portion 4c is θ b and θ c It is preferable to have an intermediate value.

[0055] In this way, by adjusting the angle of the region where the filter 4 is positioned so that the angle of the light rays from the emission surface 21 is incident at an angle nearly perpendicular to the filter 4, it is possible to efficiently extract light with wavelengths longer than λ1 (as a specific wavelength) to the outside of the optoelectronic device 100 while appropriately cutting off light with wavelengths shorter than λ1.

[0056] The shape of the flat portion 4a in a top view may be any shape that matches the shape of the ejection surface 21. The shape of the flat portion 4a can be selected from shapes such as a square, rectangle, polygon, or circle. Preferably, the shape of the flat portion 4a is similar to the shape of the ejection surface 21 in a top view (see Figure 1A) or has a radius of curvature at the corners so as to be equidistant from the ejection surface 21 (see Figure 1B).

[0057] The following describes examples of this embodiment in comparison with comparative examples.

[0058] (Examples) The optical semiconductor device 100, as illustrated in Figure 2, was configured as follows to represent the optical semiconductor device according to the embodiment. In the following description, the dimensions mentioned are the values ​​in the cross-section shown in Figure 2.

[0059] The transparent lid 3 is made of flat quartz glass with a thickness of 0.5 mm. The light-emitting element 2 uses a 0.44 mm thick ultraviolet LED chip (1 mm x 1 mm), and the distance from the emission surface 21 to the lower flat surface 32a of the transparent lid 3 is 0.55 mm. As shown in Figure 2, the transparent lid 3 has an upper flat surface 31a and a lower flat surface 32a on both the upper surface 31 and the lower surface 32 of the lid, which are horizontal to the emission surface 21. It also has inclined surfaces 31b and 32b with a normal angle of θ = 20° from the outer circumference of the emission surface 21, and inclined surfaces 31c and 32c with a normal angle of θ = 40°. The emission center wavelength of the light-emitting element 2 is 310 nm. The package substrate 1 is made of AIN ceramics, and the distance from the side of the light-emitting element 2 to the inner side of the recess in the package substrate 1 is 0.65 mm. The width of the adhesive layer 9 between the transparent lid 3 and the package substrate 1 was set to 0.6 mm.

[0060] The maximum wavelength in the wavelength range to be cut off was set to 300 nm, and the specific wavelength λ1 was set to 305 nm. Then, the filter 4 shown in Figure 3 and Table 1 above, with α=0°, was formed on the upper flat portion 31a, the inclined portion 31b, and the inclined portion 31c of the upper surface 31 of the transparent lid 3, forming the flat portion 4a, the inclined portion 4b, and the inclined portion 4c, respectively.

[0061] The emission spectrum and optical distribution characteristics of the optoelectronic device were measured, and a comparison was made between the case with and without the filter of the example. The emission spectrum of the example is shown in Figure 4A. The optical distribution characteristics for wavelengths longer than λ1 are shown in Figure 4B, and the optical distribution characteristics for wavelengths less than or equal to λ1 are shown in Figure 4C.

[0062] The emission spectrum was measured using an integrating sphere to determine the total luminous flux, and the measurement was performed using a spectrometer. The optical distribution characteristics can be measured as follows. Figure 6 shows an explanatory diagram of the measurement method for the optical distribution characteristics of the optoelectronic device 100 according to this embodiment. By placing a fiber probe A 100 mm away from the optoelectronic device 100 and changing the observation angle of the tip of the fiber probe A, the optical distribution characteristics as the dependence of the light emitted from the optoelectronic device 100 on the observation angle can be measured. The light-receiving diameter of the fiber probe A can be, for example, 3.9 mm, and the other end of the fiber probe A can be connected to a spectrometer (for example, Ocean Optics QE65 Pro) to measure the emission spectrum. In this embodiment, the optoelectronic device 100 was fixed, and the optical distribution characteristics were measured by rotating the fiber probe A in 5° increments from -60° to 60°. The measurement of the optical distribution characteristics targeted wavelengths from 200 nm to 400 nm, and values ​​from 200 nm to 305 nm and values ​​from 306 nm to 400 nm were extracted from the obtained data.

[0063] (Comparative example) The comparative example is a photoelectronic semiconductor device constructed in the same manner as in Example 1, except that the entire upper surface 31 and lower surface 32 of the transparent lid 3 are parallel to the emission surface 21, and a filter is formed on the upper surface 31 of the lid, which has no inclined portions 4b and 4c, and whose entire surface is a flat portion 4a. A comparison is made between the case with and without the filter of the comparative example, and the emission spectrum of the comparative example is shown in Figure 5A. The light distribution characteristics for wavelengths longer than λ1 are shown in Figure 5B, and the light distribution characteristics for wavelengths less than or equal to λ1 are shown in Figure 5C.

[0064] As shown in Figure 5C, when there is no inclined section, as in the comparative example, the ability to reduce the intensity of light on the wavelength side shorter than λ1 decreases significantly at angles where the absolute value of the beam angle is greater than 15°. On the other hand, when the filter has inclined sections 4b and 4c, as in the example, as shown in Figure 4C, the intensity of light on the wavelength side shorter than λ1 can be significantly reduced even at angles where the absolute value of the beam angle is greater than 15°, and as shown in Figure 4A, the emission spectrum can be reduced to near zero emission intensity below 300 nm.

[0065] (Second embodiment) The optical semiconductor device 100 according to the second embodiment differs from the first embodiment in that the shape of the transparent lid 3 differs from that of the first embodiment in that the entire upper surface 31 of the lid is parallel to the emission surface 21, and the inclined portion provided only on the lower surface 32 of the lid is one instead of two, and the cross-sectional shape of the convex shape in side view is trapezoidal. Otherwise, it is the same as the first embodiment. Since the upper surface 31 of the lid is parallel to the emission surface 21, the filter 4 is arranged on the lower side of the transparent lid 3.

[0066] As shown in Figure 7, in the optical semiconductor device 100 of this embodiment, the transparent lid 3 is plate-shaped, and the lower surface 32 of the lid is concave, indenting upwards. The lower surface 32 of the lid is shaped like a square pyramid with the upper end chamfered, similar to the upper surface 31 of the lid in the first embodiment (see Figures 1 and 2). The lower surface 32 of the lid has a flat bottom surface portion 32a and an inclined surface portion 32b formed as surface portions that form the concave shape.

[0067] The bottom portion 32a is formed in a range parallel to the emission surface 21. The flat portion 4a of the filter 4 is positioned on the bottom portion 32a.

[0068] In this embodiment, the boundary between the flat portion 4a and the inclined portion 4b is located at θ = 15°. The boundary between the flat portion 4a and the inclined portion 4b is preferably within the range of 0 ≤ θ ≤ 20° from the outer circumference of the ejection surface 21, and more preferably within the range of 0 ≤ θ ≤ 15°.

[0069] In a side view, the angle of inclination of the light rays that diagonally approach the inclined portion 4b (inclined surface portion 32b) is θ with respect to the perpendicular line from the outer circumference of the emission surface 21 toward the transparent cover 3. b When we do this, θ b The surface has a normal angle of inclination of 30°. The inclination angle of the light ray that is the normal to the inclined portion 4b and the inclined surface portion 32b is the same. The inclined surface portion 32b is formed as a four-sided slope that extends outward and downward from the bottom surface portion 32a. The inclined portion 4b of the filter 4 is positioned on the inclined surface portion 32b.

[0070] By positioning the filter 4 on the underside of the transparent lid 3 in this way, it becomes unnecessary to consider the trajectory of light after it enters the transparent lid 3, thus simplifying the design of the placement of the light cut filter.

[0071] (Modified version of the second embodiment) In the case where the lower surface 32 of the transparent lid 3 is formed in a concave shape that is recessed upward and a filter 4 is provided on the lower surface 32, the upper surface of the transparent lid 3 may be further deformed to be convex upward, as shown in Figure 8. This modified example shows a case where the upper surface of the transparent lid 3 is formed to be part of a sphere (a hemispherical lens shape in Figure 8) over its entire length.

[0072] (Third embodiment) The optical semiconductor device 100 according to the third embodiment differs from the first embodiment in that the shape of the transparent lid 3 differs from that of the first embodiment in that the entire lower surface 32 of the lid is parallel to the emission surface 21, and there is one inclined portion instead of two, and the cross-sectional shape of the convex side view is trapezoidal, but otherwise it is the same as the first embodiment. Since the entire lower surface 32 of the lid is parallel to the emission surface 21, the filter 4 is placed on the upper surface 31 of the transparent lid 3.

[0073] Since the entire surface of the lower lid surface 32 is parallel to the exit surface 21, when light is incident on the lower lid surface 32 of the transparent lid 3 at an angle other than perpendicular, the optical path depends on the thickness and refractive index of the transparent lid 3 and is refracted according to Snell's law at the interface between the closed space S and the transparent lid 3, resulting in a broken optical path. Therefore, the light rays emitted from the upper lid surface 31 deviate from the straight line of the light rays entering the lower lid surface 32. For example, if synthetic quartz (refractive index: 1.49) is used as the transparent lid 3, light incident on the lower lid surface 32 from a closed space S with a refractive index of 1 at a 30° angle will have a refraction angle of 19.6° for the light rays traveling inside the transparent lid 3.

[0074] In this embodiment, due to the geometric dimensions, the maximum inclination angle at which light enters the lower surface 32 of the transparent lid 3 is 78°. Therefore, the angle of incidence to the lower surface 32 of the lid is in the range of 0° to 78°, but the angle of refraction of light rays traveling inside the transparent lid 3 is in the range of 0° to 41°. Furthermore, considering that light rays with both positive and negative incidence angles relative to the normal of the inclined portion 4b are incident on the inclined portion 4b, it is preferable that the boundary between the flat portion 4a and the inclined portion 4b is θ=14°, which corresponds to 1 / 3 of the refraction angle range of 0° to 41°. Also, it is preferable that the normal of the inclined portion 4b is θ=27°, which corresponds to the midpoint of the refraction angle range of 14° to 41°. As a result, light from the emission surface 21 of the light-emitting element 2 is incident on not only the flat portion 4a but also the inclined portion 4b of the filter 4 at an incidence angle close to perpendicular. Specifically, the light rays incident on both the flat portion 4a and the inclined portion 4b can have as their main component light with an incidence angle in the range of 0° to 14°. Therefore, the influence of the incident angle dependence of the optical interference filter can be suppressed, and light on the shorter wavelength side can be effectively cut off while suppressing the attenuation of the output of light on the longer wavelength side of λ1, which is a specific wavelength.

[0075] As described above, an optoelectronic semiconductor device can be provided.

[0076] Furthermore, the configurations disclosed in the above embodiments (including other embodiments, the same applies hereinafter) can be applied in combination with configurations disclosed in other embodiments, as long as no inconsistencies arise. Moreover, the embodiments disclosed herein are illustrative, and the embodiments of the present invention are not limited thereto, and can be modified as appropriate without departing from the object of the present invention. [Industrial applicability]

[0077] This invention can be applied to optical semiconductor devices. [Explanation of Symbols]

[0078] 1: Package substrate 100: Optoelectronic devices 11: Bottom 13:Cylinder part 2: Light-emitting element 21: Exit surface 3: Transparent lid 31: Lid top surface 31a: Upper plane part 31b: Inclined surface part 31c: Inclined surface part 32: Lid bottom surface 32a: Bottom part 32b: Inclined surface part 32c: Inclined surface part 4: Filter 4a: Flat part 4b: Inclined part 4c: Inclined part 9: Adhesive layer A: Fiber probe P: Center S: Closed space

Claims

1. Package substrate and A light-emitting element is arranged on the upper surface of the package substrate such that the light-extracting side, which is the light extraction side, is the upper surface. A closed space is formed between the package substrate and the transparent cover that covers the light-emitting element, The transparent lid is provided with an optical interference filter having a transmittance of 50% at a specific wavelength on its surface. The aforementioned filter is It has a convex shape that points upwards. The surface forming the top of the convex shape includes the central part of the emission surface when viewed in the vertical direction. The light-emitting element is an ultraviolet LED with a light emission center wavelength of 300 nm or more and 350 nm or less, and is an optoelectronic device.

2. The photoelectronic device according to claim 1, wherein, in a side view, the surface forming the top of the convex shape is a flat portion parallel to the output surface.

3. The optical semiconductor device according to claim 1 or 2, wherein the filter has a shape in which, in a side view, a part of the polygon or a surface other than the surface forming the apex has a curve.

4. The optical semiconductor device according to any one of claims 1 to 3, wherein, in a side view of the filter, when the inclination angle of a light ray that is obliquely directed away from the surface directly above the output surface is defined as θ with respect to a perpendicular line from the outer circumference of the output surface toward the surface forming the top, the surfaces other than the top are surfaces whose normals are any inclination angle in the range of 0° < θ ≤ 90°.

5. The optical semiconductor device according to any one of claims 1 to 4, wherein the specific wavelength is a wavelength that is 3 nm or more and 10 nm shorter than the emission center wavelength of the light-emitting element.

6. Package substrate and A light-emitting element is arranged on the upper surface of the package substrate such that the light-extracting side, which is the light extraction side, is the upper surface. A closed space is formed between the package substrate and the transparent cover that covers the light-emitting element, The transparent lid is provided with an optical interference filter having a transmittance of 50% at a specific wavelength on its surface. The aforementioned filter is It has a convex shape that points upwards. The surface forming the top of the convex shape includes the central part of the emission surface when viewed in the vertical direction. The aforementioned specific wavelength is an optoelectronic device having a wavelength of 280 nm or more and 320 nm or less.

7. The photoelectronic device according to claim 6, wherein, in a side view, the surface forming the top of the convex shape is a flat portion parallel to the output surface.

8. The optoelectronic device according to claim 6 or 7, wherein the filter has a curved shape in a side view, except for a part of the polygon or the surface forming the apex.

9. The optical semiconductor device according to any one of claims 6 to 8, wherein, in a side view of the filter, when the angle of inclination of a ray that is obliquely directed away from the surface directly above the output surface is θ with respect to a perpendicular line from the outer circumference of the output surface toward the surface forming the top, the surfaces other than the top are surfaces whose normals are any angle of inclination in the range of 0° < θ ≤ 90°.

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