Optical semiconductor equipment

Abstract

To provide an optical semiconductor device capable of cutting light on a shorter wavelength side than a specific wavelength while suppressing attenuation of output of light on a longer wavelength side 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 there of the package substrate 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; a first optical interference filter 41 which is arranged on a surface of the transparent lid 3 and in which a wavelength having a transmittance of 50% at an incident angle of 0 degree is λ1 as a specific wavelength; and a second optical interference filter 42 which is arranged on the surface of the transparent lid 3 and in which the wavelength having a transmittance of 50% at an incident angle of 0 degree is λ2 (where λ1<λ2). The first optical interference filter 41 is arranged in a first region R1 including a position overlapping with a central part of the emission surface 21 when viewed in the vertical direction, and the second optical interference filter 42 is arranged in a second region R2 adjacent to the outside of the first region R1 when viewed in the vertical direction.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 allows light to be emitted uniformly perpendicular to the surface of the tube. Therefore, to cut out light below a specific wavelength, a single light cut filter could be placed in the direction of light emission from the tube. However, unlike mercury lamps and excimer lights, the light distribution from optoelectronic devices containing LED chips differs. Optoelectronic devices with flat emission surfaces, such as SMDs containing LED chips, have a wide light distribution, and light may be emitted over an angular range of approximately ±60° from the vertical.

[0008] As a filter that cuts light with a wavelength below a specific wavelength, that is, a high-pass filter, there are filters that utilize optical interference using a dielectric thin film configured as a single layer or a multilayer film, and filters that utilize absorption phenomena due to materials. A filter that utilizes optical interference (hereinafter, may be referred to as an optical interference filter) can reduce the wavelength difference between the wavelength at which the transmittance becomes 90% and the wavelength at which the transmittance becomes 10%. Therefore, it is effective when it is desired to cut the light on the shorter wavelength side than the specific wavelength while suppressing the attenuation of the light output on the longer wavelength side in the wavelength profile of the LED chip. However, an optical interference filter has a problem that it cannot effectively cut wavelengths below a specific wavelength depending on the observation angle (incident angle) because the optical path length in the filter changes depending on the incident angle of light on the filter.

[0009] Therefore, for example, in an optical semiconductor device incorporating a point light source such as an LED chip, it is desired to provide an optical semiconductor device that can cut light on the shorter wavelength side than a specific wavelength while suppressing the attenuation of the output of light on the longer wavelength side than the specific wavelength.

[0010] The present invention has been made in view of such a situation, and an object thereof is to provide an optical semiconductor device that can cut light on the shorter wavelength side than a specific wavelength while suppressing the attenuation of the output of light on the longer wavelength side than the specific wavelength.

Means for Solving the Problem

[0011] The inventors focused on arranging a plurality of optical interference filters arranged on the surface of the transparent lid with their characteristics changed according to the positional relationship from the light emitting surface of the light emitting element so that light on the shorter wavelength side than a specific wavelength can be cut while suppressing the attenuation of the output of light on the longer wavelength side than the specific wavelength, and conducted research.

[0012] The optical semiconductor device according to the present invention for achieving the above object is a package substrate, a light emitting element arranged on the upper surface of the package substrate such that the emission surface, which is the light extraction side surface, becomes the upper surface, A transparent lid that forms a closed space between the package substrate and that covers the light-emitting element, and a first optical interference filter that is disposed on the surface of the transparent lid and for which the wavelength at which the transmittance becomes 50% at an incident angle of 0 degrees is λ1 as a specific wavelength, and a second optical interference filter that is disposed on the surface of the transparent lid and for which the wavelength at which the transmittance becomes 50% at an incident angle of 0 degrees is λ2 (where λ1 < λ2), and which are provided, the first optical interference filter is disposed in a first region that includes a position overlapping the central portion of the emission surface in a vertical direction view, the second optical interference filter is disposed in a second region that is adjacent to the outside of the first region in a vertical direction view.

Advantages of the Invention

[0013] It is possible to provide an optical semiconductor device that can cut light on the shorter wavelength side than λ1 while suppressing attenuation of the output of light on the longer wavelength side than λ1 as a specific wavelength.

Brief Description of the Drawings

[0014] [Figure 1A] The figure is a top view of an optical semiconductor device according to a first embodiment. [Figure 1B] The figure is an explanatory diagram of a region in FIG. 1A. [Figure 1C] The figure is an explanatory diagram of another case of a region in FIG. 1A. [Figure 2] The figure is a cross-sectional view of an optical semiconductor device according to a first embodiment. [Figure 3] The figure is a graph showing an example of a transmittance spectrum of a first optical interference filter. [Figure 4] The figure is a graph showing an example of a transmittance spectrum of a second optical interference filter. [Figure 5] The figure is a cross-sectional view of an optical semiconductor device according to a modification of a first embodiment. [Figure 6] The figure is a top view of an optical semiconductor device according to a second embodiment. [Figure 7] The figure is a cross-sectional view of an optical semiconductor device according to a modification of a second embodiment. [Figure 8]This is a cross-sectional view of the optoelectronic device according to the third embodiment. [Figure 9] This is an explanatory diagram of the method for measuring light distribution characteristics. [Figure 10] This is a graph of the emission spectrum of the photo-synthetic device according to Example 1. [Figure 11] This is a graph of the light distribution characteristics of the optical semiconductor device according to Example 1. [Figure 12] This is a graph of the emission spectrum of the photosynthetic device according to Example 2. [Figure 13] This is a graph of the light distribution characteristics of the optical semiconductor device according to Example 2. [Figure 14] This is a graph of the emission spectrum of the optical semiconductor device according to Comparative Example 1. [Figure 15] This is a graph of the light distribution characteristics of the optical semiconductor device according to Comparative Example 1. [Figure 16] This is a graph of the emission spectrum of the optical semiconductor device relating to Comparative Example 2. [Figure 17] This is a graph of the light distribution characteristics of the optical semiconductor device relating to Comparative Example 2. [Modes for carrying out the invention]

[0015] Based on the drawings, an optical semiconductor device according to an embodiment of the present invention will be described.

[0016] (First Embodiment) (Overview) Figure 1A shows a top view 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).

[0017] First, an overview of the optical semiconductor device 100 will be described. As shown in Figure 2, the optical semiconductor device 100 comprises a package substrate 1, a light-emitting element 2 positioned on the top surface (bottom surface 11 in Figure 2) of the package substrate 1 with the light-extracting surface 21 facing upwards, a transparent cover 3 that forms a closed space S between the package substrate 1 and the light-emitting element 2 and covers the light-emitting element 2, a first optical interference filter 41 positioned on the surface of the transparent cover 3 with a specific wavelength λ1 at which the transmittance is 50% at an incident angle of 0 degrees, and a second optical interference filter 42 positioned on the surface of the transparent cover 3 with a wavelength λ2 at which the transmittance is 50% at an incident angle of 0 degrees (where λ1 < λ2). All optical interference filters in this embodiment are optical interference high-pass filters.

[0018] 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, as well as in other embodiments. For example, the side of the transparent lid 3 that is on the light-emitting element side will be referred to as the bottom surface, and the side of the transparent lid 3 opposite to the light-emitting element side will be referred to as the top surface. Also, the surface of the transparent lid 3 refers to both the top surface and the bottom surface, or either surface. Figure 1A is a top view of the transparent lid 3 viewed from above in the thickness direction of Figure 2. Figure 1B is an explanatory diagram showing the first region (R1 in the figure) and the second region (R2 in the figure) of the transparent lid 3 in Figure 2 viewed from above in the thickness direction of the transparent lid 3.

[0019] In this embodiment, the term "vertical view" refers to a view of the transparent lid 3 from above in the thickness direction of the transparent lid 3, and includes both a viewpoint from above looking at the top surface of the transparent lid 3 (hereinafter also referred to as the "top view") and a viewpoint from below looking at the bottom surface of the transparent lid 3. In the vertical view, in this embodiment, "outside" refers to the side away from the central part P shown in Figure 1B, and "inside" refers to the side towards the central part P. Similarly, "outer circumference" refers to the end of the region or range that is far from the central part P, and "inner circumference" refers to the end of the region or range that is on the side towards the central part P.

[0020] Figure 1B shows that the first region R1 includes a position that overlaps with the central part P of the exit surface 21 in a top view. The second region R2 is adjacent to the outside of the first region R1 and has an annular shape that does not overlap with the first region R1. The outer circumference of the first region R1 coincides with the inner circumference of the second region R2. The same is true when the top view is viewed in the vertical direction.

[0021] Figure 2 shows that the first optical interference filter 41 is located on the surface (top surface) of the transparent lid 3 in the first region R1. The second optical interference filter 42 is located on the surface (top surface) of the transparent lid 3 in the second region R2 and is not located in the first region R1. That is, the inner circumference of the second optical interference filter 42 in Figure 1A and the inner circumference of the second region R2 in Figure 1B are in the same position.

[0022] In this embodiment, the placement of the first optical interference filter 41 in the first region R1 means both the case where the range of the first optical interference filter 41 and the first region R1 coincide, and the case where the first optical interference filter 41 is placed in both the first region R1 and the region extending outside the first region R1. The placement of the second optical interference filter 42 in the second region R2 means both the case where the range of the second optical interference filter 42 and the second region R2 coincide, and the case where the second optical interference filter 42 is placed in both the second region R2 and the region extending outside the second region R2. However, the second optical interference filter 42 is never placed in a region inside the second region R2.

[0023] Furthermore, as shown in Figure 2, the first region R1 and the second region R2 represent three-dimensional regions in the transparent lid 3, and are separated by the path (optical path) of light emitted from the outer periphery of the emission surface 21 as it passes through the transparent lid 3.

[0024] As shown in Figure 2, the angle of the optical path of a light ray emitted diagonally from the outer circumference of the emission surface 21 toward the transparent lid 3, away from directly above the emission surface 21, is defined as the inclination angle θ with respect to the perpendicular from the outer circumference of the emission surface 21 toward the transparent lid 3. The inclination angle θ is defined as positive when moving away from the central part P and negative when moving toward the central part P. In Figure 2, the optical path of the emitted light corresponding to an inclination angle θ of 30° is θ. 30 This is illustrated by the dashed lines indicated by the sign.

[0025] Note that Figure 2 is a schematic diagram, and therefore the optical path of the light emitted from the emission surface 21 and extracted from the optical semiconductor device 100 is shown as a straight line. However, strictly speaking, when light is incident on the transparent cover 3 at an angle other than perpendicular, the optical path will deviate from a straight line because it will be refracted according to Snell's law at each interface between the closed space S, the transparent cover 3, the first optical interference filter 41 or the second optical interference filter 42, and the space outside the optical semiconductor device 100, depending on the thickness and refractive index of the transparent cover 3, the first optical interference filter 41 or the second optical interference filter 42, respectively. When designing the placement of the optical interference filters, this deviation may be taken into consideration or may be simplified and ignored. In the description of this embodiment, a straight line is assumed, ignoring the deviation.

[0026] In a vertical view, the shape of the second region R2 on the central P side (inner circumference) (i.e., the outer circumference shape of the first region R1) and the shape on the opposite side from the central P (outer circumference) can be selected from shapes such as squares, rectangles, polygons, or circles. However, as will be described later, when determining the placement of an optical interference filter having a specific optimal angle by a region defined by the inclination angle θ from the outer circumference of the output surface 21, it is preferable to have a shape similar to the shape of the output surface 21 (Figure 1B), or a shape having a certain distance (with a radius of curvature at the corner) from the outer circumference of the output surface 21 (Figure 1C). Since the difference in the effect of the present invention at corners with different shapes in Figure 1B and Figure 1C is small, the explanation of the region range by the inclination angle θ from the outer circumference of the output surface 21, based on the II-II line cross section in Figure 2, applies in both cases. Furthermore, as in the corner of the second region R2 in Figure 1C, there may be cases where there is no other region between the outer circumference of the region and the outer circumference of the transparent lid 3. In such cases, it is also possible to modify the outer circumference of the region to match the outer circumference of the transparent lid 3.

[0027] The first optical interference filter 41 and the second optical interference filter 42 are high-pass filters that, under predetermined conditions, block light below a predetermined wavelength and transmit light above a predetermined wavelength, as shown in Figures 3 and 4, respectively.

[0028] 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 is filtered out by the first optical interference filter 41 or the second optical interference filter 42, which cuts out light with wavelengths shorter than λ1, which is a specific wavelength.

[0029] 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.

[0030] (Explanation of each part) The following describes the details of each part of the optoelectronic semiconductor device 100. As shown in Figure 2, a cross-sectional view of the optoelectronic semiconductor device 100, the optoelectronic semiconductor device 100 comprises a package substrate 1, a light-emitting element 2, a transparent cover 3, and an optical interference filter disposed on the surface of the transparent cover 3, and includes a first optical interference filter 41 and a second optical interference filter 42. As shown in Figure 2, the cross-section of the optoelectronic semiconductor device 100 is symmetrical in the direction of arrow II-II in Figure 1A, for example, but it may be asymmetrical as long as the central part P of the emission surface 21 is located approximately in the center of the optoelectronic semiconductor device 100. In addition, the optoelectronic semiconductor device 100 includes electrodes and other components not shown.

[0031] 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. 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 Figure 1A).

[0032] 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.

[0033] The package substrate 1 only needs to have a shape that allows the transparent lid 3 to be placed so that the light-emitting element 2 can be arranged in the closed space S formed by joining the package substrate 1 and the transparent lid 3. For example, it may be formed 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 as 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 as a flat surface. The light-emitting element 2 is placed on the bottom surface 11 with the light-extracting surface 21, which is the light-extracting side, facing upwards. The transparent lid 3, which will be described later, is placed on the upper end of the cylindrical portion 13 of the package substrate 1.

[0034] The transparent lid 3 is made of a material that transmits light from the light-emitting element 2. The transparent lid 3 is formed, for example, in a flat plate shape. Examples of materials used to form the transparent lid 3 include glass (soda-lime glass), quartz, and metal oxides 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).

[0035] The transparent lid 3 is positioned to form a closed space S between itself and the package substrate 1, covering the light-emitting element 2 from above. In other words, the transparent lid 3 is positioned so as to completely enclose the light-emitting element 2 when viewed from above. The light-emitting element 2 is sealed in the closed space S, positioned between the bottom surface 11 of the package substrate 1 and the transparent lid 3 when viewed from above. Note that the transparent lid 3 has a closed space S between itself and the light-emitting element 2, and the transparent lid 3 and the light-emitting element 2 do not come into contact.

[0036] As shown in Figure 2, the transparent lid 3 may be, for example, a plate shape if the package substrate 1 has a shape with a recess. If the package substrate 1 is plate-shaped, the transparent lid 3 may also be a shape with a recess, for example, a bottomed cylindrical lid.

[0037] In a top view, the area of ​​the transparent cover 3 that overlaps with the light-emitting element 2 is planar, and both the top and bottom surfaces are parallel to the emission surface 21 of the light-emitting element 2.

[0038] As will be described later, a first optical interference filter 41 and a second optical interference filter 42 are placed on the surface of the transparent lid 3, and the surface of the transparent lid 3 in the area where the first optical interference filter 41 and the second optical interference filter 42 are placed is flat. The surface roughness of the transparent lid 3 is arbitrary, as long as it does not interfere with the placement of the first optical interference filter 41 and the second optical interference filter 42.

[0039] 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.

[0040] In the arrangement of the transparent cover 3 of the optical semiconductor device 100 and the emission surface 21 of the light-emitting element 2 shown in Figure 2, the light from the emission surface 21 that can be extracted to the outside of the optical semiconductor device 100 through the transparent cover 3 is emitted over an angular range of approximately 60° from the direction perpendicular to the transparent cover 3.

[0041] An optical interference filter is an optical cut-off filter that utilizes optical coherence. An optical interference filter is a laminate of two or more dielectric layers with different refractive indices (for example, two or three types). In an optical interference filter, 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 steeper the change in transmittance near a specific wavelength λ1, the better the steepness of the transmittance change near λ1. The optical interference filter in this embodiment is a high-pass filter that sets the transmittance below a predetermined wavelength (short wavelength side) at a predetermined incident angle to 50% or less. The wavelength dependence (transmission spectrum) of the transmittance of the optical interference filter can be measured using a spectrophotometer (for example, JASCO V-650). For this measurement, the optical interference filter may be formed on the surface of the transparent lid 3, or alternatively, on the surface of a quartz glass substrate or a sapphire substrate for measurement.

[0042] When the optical interference filter consists of two layers, for example, SiO2 (refractive index: 1.46) is 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) are selected as the material for the second layer. When the optical interference filter consists of three layers, for example, Al2O3 (n=1.71) or MgO (n=1.74) may be selected as the material for the third layer. When it consists of four or more layers, appropriate materials may be selected from the examples given. These layers can be deposited by known methods such as vacuum deposition, sputtering, and CVD. The optical interference filter is formed in a predetermined area using photolithography.

[0043] The characteristics of an optical interference filter, 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 of layers. In this embodiment, the case in which the optical interference filter has a layer of SiO2 and a layer of TiO2 will be described as an example.

[0044] In the following explanation, we will use the case where λ1 as a specific wavelength is 305 nm as an example. Note that λ1 is set to reduce the light output in the wavelength range to be cut off, within the range between the emission center wavelength of the light-emitting element 2, where we want to maintain the emission output as much as possible (in this embodiment, we will explain the case where it is 310 nm as an example), and the maximum wavelength in the wavelength range to be cut off (for example, 300 nm) (for example, between 300 nm and 310 nm). If the light-emitting element 2 is an ultraviolet LED with an emission center wavelength of 300 nm to 350 nm, the wavelength full width at half maximum (FWHM) in its wavelength profile is about 4 to 8 nm on the shorter wavelength side of the emission center wavelength, and considering the steep characteristics of the optical interference filter near λ1, it is preferable that λ1 is a wavelength that is 3 nm to 10 nm shorter than the emission center wavelength.

[0045] In the arrangement of the transparent cover 3 of the optoelectronic device 100 and the emission surface 21 of the light-emitting element 2 shown in Figure 2, in the region of the transparent cover 3 that overlaps with the emission surface 21 of the light-emitting element 2 when viewed in the vertical direction, the incidence angle of the light emitted from the emission surface 21 and incident on the transparent cover 3 is predominantly around 0°. Therefore, an optical interference filter suitable for an incidence angle near 0° is placed in this region. On the other hand, the incidence angle of the light emitted outward from the outer periphery of the emission surface 21 of the light-emitting element 2 and incident on the transparent cover 3 when viewed in the vertical direction is predominantly greater than 0°. In such regions, an optical interference filter suitable for light with a large incidence angle is placed.

[0046] Figure 3 shows an example of the transmission spectrum of an optical interference filter at 5° intervals within the range of incident angles from 0° to 60°. In Figure 3, the vertical axis, "Filter Transmittance," represents the light transmittance of the optical interference filter. Hereafter, the incident angle at which the wavelength λ1 results in a 50% transmittance in the optical interference filter will be referred to as the optimal angle. Let the angle of the optimal angle be α.

[0047] In the optical interference filter shown in Figure 3, the filter transmittance on the vertical axis is 50% when the wavelength on the horizontal axis is λ1 (305 nm) at an incident angle of 0°; therefore, the optimal angle for the optical interference filter in Figure 3 is α = 0°. Such an optical interference filter is placed as the first optical interference filter 41 in a region that overlaps with the emission surface 21 of the light-emitting element 2 when viewed in the vertical direction of the transparent cover 3. In the first optical interference filter 41, as the incident angle increases from the optimal angle α = 0°, the wavelength range in which the transmittance is 50% or less shifts to the shorter wavelength side.

[0048] Furthermore, in the optical interference filter of Figure 4, the filter transmittance on the vertical axis is 50% when the wavelength on the horizontal axis is λ1 (305 nm) at an incident angle of 30°, so the optimal angle for the optical interference filter of Figure 4 is α = 30°. Also, the wavelength λ2 at which the transmittance is 50% at an incident angle of 0° is 317 nm, and λ2 > λ1. Thus, an optical interference filter with a larger optimal angle compared to Figure 3 is placed as the second optical interference filter 42 in the outer region where the inclination angle from the emission surface 21 of the light-emitting element 2 is greater than 0° when viewed in the vertical direction of the transparent lid 3. In the second optical interference filter 42, as the incident angle increases from the optimal angle α = 30°, the wavelength range at which the transmittance is 50% or less shifts to the shorter wavelength side, and as the incident angle decreases from the optimal angle α = 30°, the wavelength range at which the transmittance is 50% or less shifts to the longer wavelength side.

[0049] Consider the case where an optical interference filter having the transmittance characteristics shown in Figure 3 is formed on the entire upper surface of the transparent lid 3. As the inclination angle θ from the outer circumference of the light-emitting element 2 increases, the incident angle to the filter provided on the upper surface 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. For example, at an inclination angle θ of the optimal angle +35° (incidence angle 35° in Figure 3), the transmittance of the maximum wavelength (300nm) in the wavelength band to be cut is close to 100%, while at an inclination angle θ of the optimal angle +15° (incidence angle 15° in Figure 3), the transmittance of the maximum wavelength (300nm) in the wavelength band to be cut is less than 10%.

[0050] Furthermore, consider the case where an optical interference filter having the transmittance characteristics shown in Figure 4 is formed, for example, on the entire upper surface of the transparent lid 3. In the range where the inclination angle θ from the outer circumference of the light-emitting element 2 is near the optimal angle (α=30°) and greater than 30°, light in the wavelength band below λ1 can be effectively cut. However, in regions where the inclination angle θ is smaller than the optimal angle, such as the region overlapping with the emission surface 21 of the light-emitting element 2, the transmittance of light with wavelengths longer than λ1 (305nm), including the emission center wavelength of 310nm of the light-emitting element 2, is low, and the emission output decreases. In particular, at inclination angles θ smaller than the optimal angle -5° (incident angle 25° in Figure 4), the transmittance of the emission center wavelength of 310nm decreases significantly.

[0051] Therefore, optical interference filters with different optimal angles are prepared, and the region where the optical interference filters are to be installed is determined using the tilt angle. Optical interference filters with different optimal angles are then installed in each region. By not placing optical interference filters with an optimal angle greater than or equal to the optimal angle in regions with a tilt angle smaller than the optimal angle of -5°, the attenuation of light in the wavelength band greater than λ1 can be suppressed.

[0052] The following considers the case where N (N is a natural number) optical interference filters are used. The filters are numbered by a natural number n (n=1 to N) in order from the innermost to the outermost, and these numbered filters are referred to as the nth optical interference filter. The region where the nth optical interference filter is located is the nth region R. n Let's assume the nth region R n The larger the value of n, the further out the region is located, and the regions do not overlap.

[0053] The optimal angle of the nth optical interference filter is α n Therefore, α1 < α2 < ... < α N As shown above, the larger the value of n, the larger the optimal angle. When N=2, it is preferable that 0°≦α1≦20° and 20°≦α2≦40°. Also, when N≧3, α1~α NIt is preferable that the intervals are equally spaced by an angle obtained by dividing the half value of the light distribution angle of the optical semiconductor device 100 (for example, 60°) by N, but they do not necessarily have to be equally spaced. For example, when the optimum angle of the first optical interference filter is α1 = 0°, if N = 3, it is preferable that α1 = 0°, α2 = 20°, α3 = 40°, and if N = 6, it is preferable that α1 = 0°, α2 = 10°, α3 = 20°, α4 = 30°, α5 = 40°, α6 = 50°.

[0054] The nth region R such as the first region R1 and the second region R2 n The boundary line that determines the range is defined by the optimum angle α of the nth optical interference filter n and the tilt angle θ. The nth region means a three-dimensional region from when the light emitted from the emission surface 21 of the light-emitting element 2 passes through the lower surface to the upper surface of the transparent lid 3 having a thickness. In the following description, the positions of the outer circumference or the inner circumference of each region such as the first region R1 and the second region R2 will be described using the tilt angle θ from the outer circumference of the emission surface 21. The position of the outer circumference will be denoted as θout and the position of the inner circumference will be denoted as θin. Also, for example, the position of the outer circumference of the first region R1 will be denoted as θout(R1), and the position of the inner circumference of the second region R2 will be denoted as θin(R2), etc.

[0055] The outer circumference of the first region R1 and the inner circumference θin(R n (n = 2 to N) and the outer circumference θout(R n ) of the nth region R after the second region n can be described as follows using the optimum angle α of the nth optical interference filter. Starting from n = N and descending in order to n = 1, θout(R n )(where n = 1 to N) and θin(R n )(where n = 2 to N) may be sequentially determined. · The first region R1 includes a position overlapping the central portion P of the emission surface 21 in the vertical view. · The outer circumference θout(R n ) of the nth region R n ) α n -5° < θout(R n ) = θin(R n+1 ) for n = 1 α n ​​<θout(R n ) = θin(R n+1 ) When n=2 to N-1 α n <θout(R n )≦α n +35° when n=N Preferably α n <θout(R n )≦α n +15° when n=N The nth region R when n is between 2 and N n The inner circumference θin(R n ) α n -5°≦θin(R n )≦α n ...(Formula 1) Preferably α n -1°≦θin(R n )≦α n

[0056] nth region R n The relationship between this and the nth optical interference filter is as follows: • The nth optical interference filter is in the nth region R n It should be provided to include it. When n is between 2 and N, the inner circumference of the nth optical interference filter is made to match the inner circumference of the nth region. When n is between 1 and N, the outer perimeter of the nth optical interference filter can extend to a position that coincides with or exceeds the outer perimeter of the nth region.

[0057] The outer circumference of the nth optical interference filter can extend to any position that is at most the outer circumference of the transparent cover 3.

[0058] For example, if odd and even optical interference filters n are placed on the same surface of the transparent lid 3, the outer circumference of the nth optical interference filter may coincide with the inner circumference of the (n+1)th optical interference filter, or it may extend beyond the inner circumference of the (n+1)th optical interference filter into the (n+1)th region. If odd and even optical interference filters n are placed on different surfaces of the transparent lid 3, the outer circumference of the nth optical interference filter may be within the (n+1)th region, coincide with the inner circumference of the (n+2)th optical interference filter, or even extend beyond the inner circumference of the (n+2)th optical interference filter into the (n+2)th region. In other words, it is not permitted to place the inner circumference of each optical interference filter in a region inside the region in which the optical interference filter is provided. On the other hand, it is permitted to place the outer circumference of each optical interference filter in a region outside the region in which the optical interference filter is provided. However, as shown in Figures 3 and 4, optical interference filters do not always have 100% transmittance even in the wavelength range through which light is transmitted, so there is a slight unintended attenuation of output in the wavelength range longer than λ1. To reduce even this slight attenuation of output, the outer edge of the nth optical interference filter is α n It is preferable to keep it within +35°, α n It is more preferable to keep it within +15°. The outer edge of the nth optical interference filter in the vertical direction view is in the nth region R in the vertical direction view. n The shape may correspond to the outer perimeter shape.

[0059] (First Embodiment) The following description assumes N=2, and the first embodiment will be explained using the optical interference filters shown in Figure 3 (α1=0°) and Figure 4 (α2=30°) above, respectively, as the first optical interference filter 41 and the second optical interference filter 42. As shown in Figures 1A and 2, in the first embodiment, both the first optical interference filter 41 and the second optical interference filter 42 are installed on the upper surface of the transparent lid 3.

[0060] In Figure 2, the inner circumference θin(R2) of the second region R2, where the second optical interference filter 42 (α2=30°) is installed, is set to 30°. Also, the outer circumference θout(R1) of the first region R1, where the first optical interference filter 41 (α1=0°) is installed, is set to coincide with the inner circumference of the second region R2. The outer circumference θout(R2) of the second region R2 is not particularly limited because N=2 and there is no region outside the second region R2, but for example, since α2=30°, it can be selected from the range 30°<θout(R2)≦30°+35°, and can be set to 60°, for example.

[0061] The first optical interference filter 41 is always placed in a region including the first region R1 in order to efficiently cut out light with a λ of less than or equal to λ from the light-emitting surface 21 of the light-emitting element 2, i.e., light with an incident angle of 0 degrees. No other placements besides the first optical interference filter 41, such as the second optical interference filter 42, are permitted in the first region R1. The outer circumference of the first optical interference filter 41 may extend to the second region R2 adjacent to the outside of the first region R1, and even further out. Figure 2 illustrates a case where the outer circumference of the first optical interference filter 41 is located at an inclination angle θ = 30° from the outer circumference of the light-emitting surface 21, and the second optical interference filter 42 is located in the second region R2, with the inner circumference of the second optical interference filter 42 located at an inclination angle θ = 30° from the outer circumference of the light-emitting surface 21. Light with a λ of less than or equal to λ incident at a large inclination (for example, an incident angle of 30°) relative to the first optical interference filter 41 cannot be sufficiently cut out and will be transmitted. Therefore, the region where the light from the output surface 21 is incident on the transparent lid 3 at a large inclination, that is, the region where the inclination angle θ = 30° or more from the outer circumference of the output surface 21, is defined as the second region R2. By placing the second optical interference filter 42 with an optimal angle of 30° in the second region R2, it is possible to efficiently cut out light on the shorter wavelength side than λ1 while suppressing the attenuation of the output of light on the longer wavelength side than λ1, thereby enabling the light on the longer wavelength side than λ1 to be efficiently radiated to the outside of the optoelectronic device 100. However, if the second optical interference filter 42 with an optimal angle of 30° is placed in a position where the inclination angle θ to the transparent lid 3 is clearly smaller than the optimal angle of 30° (for example, in the range of inclination angles θ that is more than 5° but less than 25° than the optimal angle α2), it is undesirable because the output on the longer wavelength side than λ1, which is not to be attenuated, will be greatly attenuated.

[0062] Thus, the first optical interference filter 41 is used as an optical interference filter for vertical light incident at an angle nearly perpendicular to the transparent lid 3, and separately from the first optical interference filter 41, the second optical interference filter 42 is used as an optical interference filter for oblique light incident at an angle tilted from perpendicular to the transparent lid 3. That is, in the region of the tilt angle θ which is equal to or greater than the optimal angle (at least 5° or more from the optimal angle), an optical interference filter having that optimal angle is placed. This makes it possible to efficiently extract light with wavelengths longer than λ1 to the outside of the optoelectronic device 100 while appropriately cutting out light with wavelengths shorter than λ1.

[0063] (Modification 1 of the first embodiment) In the first embodiment described above, the case in which both optical interference filters are installed on the upper surface of the transparent lid 3 was illustrated and explained as shown in Figure 2. However, as shown in the cross-sectional view of Figure 5 (showing the same cross-section as in Figure 2), the optical interference filters may also be placed on the lower surface of the transparent lid 3. The first optical interference filter 41 and the second optical interference filter 42 may be placed on the lower surface of the transparent lid 3, or one may be placed on the lower surface of the transparent lid 3 and the other on the upper surface of the transparent lid 3.

[0064] Figure 5 shows a modified example in which the first optical interference filter 41 is placed on the lower surface of the transparent lid 3 and the second optical interference filter 42 is placed on the upper surface of the transparent lid 3. By placing the first optical interference filter 41 on the lower surface of the transparent lid 3 in this way, the first optical interference filter 41 can be positioned closer to the light-emitting element 2, and light with an incident angle nearly perpendicular to the first optical interference filter 41 can be efficiently filtered. In addition, since the optical path after entering the transparent lid 3 does not need to be considered, the design of the placement position of the optical interference filters becomes easier.

[0065] Furthermore, compared to forming optical interference filters with different optimal angles (in the modified example 1, the first optical interference filter 41 and the second optical interference filter 42) on the same surface of the transparent cover 3, the range of inclination angles θ borne by each optical interference filter can be widened, thereby appropriately suppressing the attenuation of light output on the wavelength side longer than λ1, which is the specific wavelength. In addition, the attachment of each optical interference filter to the transparent cover 3 becomes easier, and the manufacturing of the optical semiconductor device 100 becomes easier.

[0066] Figure 5 shows a case where the optimal angle α2 of the second optical interference filter 42 is 30°, similar to the first embodiment, and the inner circumference of the second region is θin(R2) = 30°. The inner circumference of the second optical interference filter 42 coincides with the inner circumference of the second region R2 described above. Furthermore, the outer circumference of the first optical interference filter 41 extends into the second region R2, and the outer circumference of the first optical interference filter 41 is positioned at a position where θ = 35° from the outer circumference of the emission surface 21.

[0067] In Figure 5, the first optical interference filter 41 and the second optical interference filter 42 overlap in the range of tilt angle θ = 30° to 35°. That is, the outer circumference of the first optical interference filter 41 is within the range of the second optical interference filter 42 when viewed in the direction of tilt angle θ. By overlapping the optical interference filters in the direction of a predetermined tilt angle θ in this way, the allowable range of error in the placement position of the optical interference filters during formation is expanded, while eliminating the gap between the first optical interference filter 41 and the second optical interference filter 42 with respect to the light radiated from the output surface 21. This prevents a decrease in performance in cutting light on the shorter wavelength side of λ1 while suppressing the attenuation of the output of light on the longer wavelength side of λ1 as a specific wavelength. Furthermore, due to the relationship between the optimal angle and placement position of the first optical interference filter 41 and the second optical interference filter 42 in this embodiment, light on the longer wavelength side of λ1 that has passed through the optical interference filter with a small optimal angle (first optical interference filter 41) is not significantly cut when it passes through the optical interference filter with a large optimal angle (second optical interference filter 42).

[0068] (Second embodiment) In the second embodiment, as shown in Figure 6, the optical semiconductor device 100 differs in that it further includes a third optical interference filter 43 as an optical interference filter, and is otherwise the same as Modification 1 of the first embodiment. Below, we will mainly explain the differences from Modification 1 of the first embodiment, such as the selection of the optimal angle when N=3.

[0069] In this embodiment, the wavelength λ3 at which the third optical interference filter 43 has a transmittance of 50% at an incident angle of 0 degrees is set to λ2 < λ3. The preferred range for the optimal angle α3 of the third optical interference filter 43 is 40° ≤ α3 ≤ 60° when using three types of optical interference filters: the first optical interference filter 41, the second optical interference filter 42, and the third optical interference filter 43.

[0070] When using three types of optical interference filters, a first optical interference filter 41, a second optical interference filter 42, and a third optical interference filter 43, it is preferable to set the optimal angle α2 of the second optical interference filter 42 to be smaller than in the case where only two types of optical interference filters, the first optical interference filter 41 and the second optical interference filter 42, are used, as in the first embodiment. Furthermore, it is preferable to set the optimal angles α1, α2, and α3 to be approximately equal in intervals. In this embodiment, the optimal angles α1, α2, and α3 may be 0°, 20°, and 40° as examples.

[0071] The third region R3 is the region where the third optical interference filter 43 is always placed. That is, the region where the third optical interference filter 43 is placed includes the third region R3 that overlaps with the upper surface of the transparent lid 3. The outer circumference of the third region R3 is preferably in the range α3 < θout(R3) ≤ α3 + 35°, and the inner circumference can be α3 - 5° < θin(R3) ≤ α3. When using a third optical interference filter 43 with an optimal angle α3 of 40°, a general range for the third region R3 is θ between 40° and 65°. In this embodiment, for example, the outer circumference θout(R3) is 60° and the inner circumference θin(R3) is 40°. The third region R3 is an annular region that surrounds the second region R2 located inside it.

[0072] The outer circumference of the second region R2 coincides with the inner circumference of the third region R3, so θout(R2) = θin(R3). The inner circumference of the second region R2 can be such that α2 - 5° < θin(R2) ≤ α2, similar to the inner circumference of the third region R3. In this embodiment, for example, the inner circumference θin(R2) is 20° and the outer circumference θout(R2) is 40°. The second region R2 is an annular region that surrounds the first region R1 located inside it.

[0073] The outer circumference of the first region R1 coincides with the inner circumference of the second region R2, so θout(R1) = θin(R2). In this embodiment, for example, the outer circumference θout(R1) is 20°.

[0074] The first optical interference filter 41 is positioned to encompass the first region R1. The outer periphery of the first optical interference filter 41 may extend beyond the outer periphery of the first region R1 to the second region R2 located outside of it, and to the third region R3 located even further outside. Figure 6 illustrates an example where the first optical interference filter 41 is positioned at an inclination angle θ = 35°, with its outer periphery within the second region, and the first optical interference filter 41 extending from the first region R1 to the second region R2.

[0075] The second optical interference filter 42 is positioned to encompass the second region R2. The inner circumference of the second optical interference filter 42 and the inner circumference of the second region R2 are aligned, and the second optical interference filter 42 is not permitted to be placed in the first region R1. On the other hand, the outer circumference of the second optical interference filter 42 may extend beyond the outer circumference of the second region R2 to the third region R3 located outside of it. Figure 6 illustrates a case where the inner circumference of the second optical interference filter 42 is located at the boundary between the second region R2 and the first region R1, and the outer circumference of the second optical interference filter 42 extends from the second region R2 to the third region R3.

[0076] The third optical interference filter 43 is positioned to encompass the third region R3. The inner circumference of the third optical interference filter 43 and the inner circumference of the third region R3 are aligned, and the placement of the third optical interference filter 43 in the second region R2 is not permitted. On the other hand, the placement of the first optical interference filter 41 and / or the second optical interference filter 42 is permitted in the third region R3.

[0077] Figure 6 shows an example of this embodiment in which the inner circumference of the third region R3 and the outer circumference of the second region R2 are at θin(R3)=θout(R2)=40°, the inner circumference of the second region R2 and the outer circumference of the first region R1 are at θin(R2)=θout(R1)=20°, the first optical interference filter 41 is provided on the lower surface of the transparent lid 3 with its outer circumference extending to θ=35°, and the second optical interference filter 42 and the third optical interference filter 43 are provided on the upper surface of the transparent lid 3, with the outer circumference of the second optical interference filter 42 extending to θ=45° and the outer circumference of the third optical interference filter 43 extending to the outer circumference of the transparent lid 3.

[0078] In the vertical view, the shape of the region outside the second region R2, such as the third region R3, is preferably similar to the shape of the second region R2 as exemplified in Figures 1B and 1C described above. The third optical interference filter 43 may have a shape that corresponds to the shape of the third region R3.

[0079] In Figure 6, the inner end of the third optical interference filter 43, which is the inner circumference, overlaps with the outer end of the second optical interference filter 42, which is the outer circumference, in the vertical direction, and is positioned on the upper surface side of the second optical interference filter 42. This arrangement is preferable because it facilitates the deposition and pattern formation of the optical interference filter, making it easier to manufacture.

[0080] As in this embodiment, by arranging three or more types of optical interference filters (three types in this embodiment) with different optimal angles from the central part of the emission surface 21 outwards, in order from the optical interference filter with the smallest optimal angle to the optical interference filter with the largest optimal angle, it is possible to cut out light on the shorter wavelength side than λ1 even more effectively while appropriately suppressing the attenuation of the output of light on the longer wavelength side than λ1. This makes it possible to radiate light on the longer wavelength side than λ1 more efficiently to the outside of the optical semiconductor device 100.

[0081] (Modified version of the second embodiment) Figure 7 shows modifications of the second embodiment described above, including the range of the first region R1, the arrangement of the third optical interference filter 43 on the transparent cover 3, and the installation range of the second optical interference filter 42.

[0082] In this modified example, the first optical interference filter 41 has an optimal angle α1 of 0°, the second optical interference filter 42 has an optimal angle α2 of 20°, and the third optical interference filter 43 has an optimal angle α3 of 40°.

[0083] The inner circumference of the third region R3 and the outer circumference of the second region R2 have a θ of 40°, while the inner circumference of the second region R2 and the outer circumference of the first region R1 have a θ of 20°.

[0084] The first optical interference filter 41 is positioned on the underside of the transparent cover 3 so as to include the first region R1, and the outer edge of the first optical interference filter 41 is located at a position where θ = 35°.

[0085] The second optical interference filter 42 is positioned on the upper surface of the transparent cover 3 so as to include the second region R2. The inner circumference of the second optical interference filter 42 coincides with the inner circumference of the second region R2 and is located at a position where θ = 20°. The outer circumference of the second optical interference filter 42 extends to a position where θ = 55°.

[0086] The third optical interference filter 43 is positioned on the underside of the transparent cover 3 so as to include the third region R3. The inner circumference of the third optical interference filter 43 coincides with the inner circumference of the third region R3 and is located at a position where θ = 40°. The outer circumference of the third optical interference filter 43 is located at a position where θ = 60° or more and extends to the very edge of the outer circumference of the transparent cover 3 facing the closed space S.

[0087] If the angle of incidence of light to the optical interference filter is greater than the optimal angle of that optical interference filter, there is no risk of wavelengths longer than λ1 being cut off. Therefore, from the standpoint of maintaining the output of light with wavelengths longer than λ1, the range in which the optical interference filter is placed is not limited as long as the tilt angle is greater than or equal to the optimal angle of that filter, as in this modified example.

[0088] Furthermore, in this modified example, within the range of tilt angles 40°≦θ≦55°, light transmitted through the third optical interference filter 43 is incident on the second optical interference filter 42. In this way, when an optical interference filter with a large optimal angle is provided on the lower surface of the transparent lid 3, and an optical interference filter with a small optimal angle is provided on the upper surface of the transparent lid 3 up to a range of tilt angles that greatly exceeds the optimal angle, light transmitted through the optical interference filter with a large optimal angle is incident on the optical interference filter with a small optimal angle. Since light is incident on the optical interference filter provided in the range of tilt angles that greatly exceeds the optimal angle at an angle larger than the optimal angle, there is no risk of light with wavelengths longer than λ1 being cut off. Therefore, light with wavelengths longer than λ1 that has been transmitted through the optical interference filter with a large optimal angle (third optical interference filter 43) is not significantly cut off when it is transmitted through the optical interference filter with a small optimal angle (second optical interference filter 42).

[0089] (Third embodiment) Figure 8 illustrates a further modification of the second embodiment, where six optical interference filters with different optimal angles are arranged. In this case, the wavelengths λ1 to λ6, which result in a transmittance of 50% at an incident angle of 0 degrees, are λ1 < λ2 < λ3 < λ4 < λ5 < λ6. The optimal angles α1 to α6 of the first optical interference filter 41 to the sixth optical interference filter 46 are α1 < α2 < α3 < α4 < α5 < α6. An example of the optimal angle values ​​α1 to α6 for the first optical interference filter 41 to the sixth optical interference filter 46 are 0°, 10°, 20°, 30°, 40°, and 50°, in that order.

[0090] The first region R1 to the sixth region R6, where the first optical interference filter 41 to the sixth optical interference filter 46 are located, are defined in the same way as the relationship between the first region R1 to the third region R3 described in the second embodiment. The first region R1 to the sixth region R6 are non-overlapping regions and are arranged adjacently in this order, moving outward from the first region R1. The first optical interference filter 41 to the sixth optical interference filter 46 are always located in the first region R1 to the sixth region R6, respectively. The regions where the first optical interference filter 41 to the sixth optical interference filter 46 are located encompass the first region R1 to the sixth region R6 that overlap with the surface of the transparent lid 3. The inner circumferences of the second region R2 to the sixth region R6 coincide with the inner circumferences of the second optical interference filter 42 to the sixth optical interference filter 46. As an example, the position θin of the inner circumference of the second region R2 to the sixth region R6 coincides with the optimal angle α2 to α6 values ​​of 10°, 20°, 30°, 40°, and 50°, respectively. The first, third, and fifth optical interference filters are positioned on the underside of the transparent cover 3, while the second, fourth, and sixth optical interference filters are positioned on the upper side of the transparent cover 3. The outer edges of the first through fifth optical interference filters are located within the ranges of the second region R2 through the sixth region R6, respectively.

[0091] (Examples) The following describes examples of this embodiment in comparison with comparative examples.

[0092] (Example 1) An optical semiconductor device 100 equipped with three optical interference filters, as illustrated in Figure 7, was configured as follows to constitute the optical semiconductor device according to Example 1. In the following description, the dimensions mentioned refer to the values ​​in the cross-section shown in Figure 7.

[0093] 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 bottom surface of the transparent lid 3 is 0.135 mm. 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 is 0.6 mm.

[0094] 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.

[0095] The first optical interference filter 41 had an optimal angle α1 of 0° and a thickness of 1.977 μm (40 pairs). The first optical interference filter 41 was positioned at a location where its outer circumference was at θ=30°, that is, in a top view, it was positioned in a region extending 0.078 mm outward from the outer circumference of the emission surface 21.

[0096] The second optical interference filter 42 had an optimal angle α2 of 20° and a thickness of 1.623 μm (40 pairs). The second optical interference filter 42 was positioned in a region where its outer circumference was in the range of 20° ≤ θ ≤ 55°, that is, in a top view, it extended outward from the outer circumference of the emission surface 21 in a range of 0.349 mm to 1.237 mm.

[0097] The third optical interference filter 43 had an optimal angle α3 of 40° and a thickness of 2.098 μm (41 pairs). The third optical interference filter 43 was positioned in the range of 40°≦θ from the outer periphery of the emission surface 21, that is, in a top view, in a region extending outward from the outer periphery of the emission surface 21, from 0.113 mm to 0.65 mm.

[0098] Table 1 shows the refractive index and film thickness data for each layer of the first optical interference filter 41, the second optical interference filter 42, and the third optical interference filter 43. The SiO2 film (refractive index: 1.46) and the TiO2 film (refractive index: 2.26) were deposited to their respective thicknesses by sputtering, and then formed within the specified range using photolithography and lift-off methods.

[0099] [Table 1]

[0100] The emission spectrum and light distribution characteristics of the photoelectronic device according to Example 1 were measured.

[0101] 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 9 shows an explanatory diagram of the method for measuring 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 were extracted from the obtained data.

[0102] Figure 10 shows the emission spectrum of the optical semiconductor device according to Example 1, and Figure 11 shows the optical distribution characteristics. In Figure 10, the emission spectrum measured with all optical interference filters removed from the optical semiconductor device according to Example 1 is also shown. Similarly, Figure 11 shows the optical distribution characteristics measured with all optical interference filters removed from the optical semiconductor device according to Example 1.

[0103] (Example 2) The optical semiconductor device according to Example 2 is the same as that of Example 1, except for the number and arrangement of the types of optical interference filters. The optical semiconductor device according to Example 2 is configured to have six types of optical interference filters with different optimal angles, following the optical semiconductor device 100 shown in Figure 8. The optimal angles of the first optical interference filter 41 to the sixth optical interference filter 46 are 0°, 10°, 20°, 30°, 40°, and 50°, in that order. The first optical interference filter 41 is arranged in the range where θ ≤ 15°, and the second optical interference filter 42 to the sixth optical interference filter 46 are arranged in the ranges of 10° ≤ θ ≤ 25°, 20° ≤ θ ≤ 35°, 30° ≤ θ ≤ 45°, 40° ≤ θ ≤ 55°, and 50° ≤ θ, respectively. The thicknesses and number of pairs of the first optical interference filters 41 to the sixth optical interference filters 46 are 1.977 μm (40 pairs), 1.526 μm (40 pairs), 1.623 μm (40 pairs), 1.668 μm (40 pairs), 2.098 μm (41 pairs), and 2.130 μm (41 pairs), respectively. Note that the first optical interference filter 41, the third optical interference filter 43, and the fifth optical interference filter 45 in Example 2 are the same as the first optical interference filter 41, the second optical interference filter 42, and the third optical interference filter 43 in Example 1.

[0104] Table 2 shows the refractive index and film thickness data for each layer of the pair of second optical interference filters 42, fourth optical interference filters 44, and hexa-optical interference filters 46 in Example 2. The SiO2 film (refractive index: 1.46) and TiO2 film (refractive index: 2.26) were deposited to their respective thicknesses by sputtering and formed within the predetermined range using photolithography and lift-off methods.

[0105] [Table 2]

[0106] Figure 12 shows the emission spectrum of the optoelectronic device according to Example 2, and Figure 13 shows the light distribution characteristics. In Figure 12, the emission spectrum measured with all optical interference filters removed from the optoelectronic device according to Example 2 is also shown. Similarly, Figure 13 shows the light distribution characteristics measured with all optical interference filters removed from the optoelectronic device according to Example 2.

[0107] (Comparative example) The comparative optical semiconductor device differed from the embodiment in that it used only one type of optical interference filter, while all other aspects remained the same. The comparative optical semiconductor device was constructed by removing the second optical interference filter 42 and the third optical interference filter 43 from the optical semiconductor device 100 shown in Figure 7, and arranging an optical interference filter with a predetermined optimal angle, similar to the first optical interference filter 41, across the entire lower surface of the transparent cover 3.

[0108] The optical interference filter had an optimal angle of either 0° (the same as the first optical interference filter 41 in Example 2) or 30° (the same as the fourth optical interference filter 44 in Example 2). Hereinafter, the optical semiconductor device using an optical interference filter with an optimal angle of 0° will be referred to as Comparative Example 1, and the optical semiconductor device using an optical interference filter with an optimal angle of 30° will be referred to as Comparative Example 2.

[0109] Figures 14 and 16 show the emission spectra of the optical semiconductor devices of Comparative Example 1 and Comparative Example 2, respectively, and Figures 15 and 17 show the optical distribution characteristics, respectively. Figures 14 and 16 also show the emission spectra measured with all optical interference filters removed from the optical semiconductor device of Example 1. Similarly, Figures 15 and 17 also show the optical distribution characteristics measured with all optical interference filters removed from the optical semiconductor device of Example 1.

[0110] Based on the results shown in Figures 10 to 17, the following can be inferred about the examples and comparative examples.

[0111] Compared to the case without an optical interference filter and the comparative example, Examples 1 and 2 show a decrease in output below the specific wavelength λ1 (305 nm), with the emission output below 300 nm being close to zero. In contrast, the emission output around the emission peak wavelength (310 nm) is maintained. In other words, the attenuation of light on the wavelength side longer than λ1 is suppressed while cutting out light on the wavelength side shorter than λ1.

[0112] As shown in Figures 10, 12, 14, and 16, compared to the case without an optical interference filter and the comparative example, Examples 1 and 2 show a decrease in output below the specific wavelength λ1 (305 nm), with the emission output below 300 nm being close to zero. In contrast, the emission output around the emission peak wavelength (310 nm) is maintained. In other words, the attenuation of the output of light on the wavelength side longer than λ1 is suppressed while cutting out light on the wavelength side shorter than λ1.

[0113] In comparison with Comparative Example 1 (see Figure 15), which employs an optical interference filter with the same characteristics as the first optical interference filter in Examples 1 and 2 but with a different placement range, Examples 1 and 2 (see Figures 11 and 13) are able to cut out light on the short-wavelength side even at positions where the absolute value of the beam angle [°] is large, and the cut-off rate for wavelengths below 305 nm is high.

[0114] Therefore, it is clear that by employing two or more optical interference filters with sequentially different optimal angles, it is possible to provide an optoelectronic device that can more effectively cut out light on the shorter wavelength side of λ1 while suppressing the attenuation of the output of light on the longer wavelength side of λ1, which is a specific wavelength.

[0115] In a comparison between Examples 1 and 2, Example 2 (see Figure 13), in which the optimal angle of each of the six types of optical interference filters was increased by 10° each, showed a greater cutoff effect for wavelengths below 305 nm compared to Example 1 (see Figure 11), in which the optimal angle of each of the three types of optical interference filters was increased by 20° each.

[0116] Therefore, by increasing the number of optical interference filters used and arranging them according to the incident angle (angle θ) of the light incident on each optical interference filter, the cut-off effect for wavelengths below λ1 (305 nm) can be greatly increased. This allows for effective cut-off of light shorter than a specific wavelength while suppressing attenuation of the output of light longer than that specific wavelength.

[0117] In Comparative Example 2, compared to Examples 1 and 2, the optical interference filter with an excessively large optimal angle is positioned in overlap with the light-emitting element in the vertical view. As shown in Figure 16, while the output below the specific wavelength λ1 (305 nm) is reduced compared to the case without the optical interference filter, the emission intensity above 305 nm is also reduced to 60% or less. This is because, as shown in Figure 4, the transmission spectrum of the optical interference filter with an optimal angle of 30° used in Comparative Example 2 has the characteristic of cutting off light in the wavelength band longer than the specific wavelength λ1 when light is incident on the optical interference filter at an angle of less than 30°. Compared to Examples 1 and 2, the optical interference filter with an excessively large optimal angle is positioned in overlap with the light-emitting element in the vertical view. In other words, the attenuation of light output on the wavelength side longer than the specific wavelength λ1 cannot be suppressed. Comparative Example 2, as shown in Figure 17, effectively cuts out light with wavelengths below 305 nm when the beam angle (incident angle) is between 0° and 45°. However, as shown in Figure 16, it significantly attenuates the output of light with wavelengths longer than λ1, which is the specific wavelength, making it impractical.

[0118] As described above, an optoelectronic semiconductor device can be provided.

[0119] 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]

[0120] This invention can be applied to optical semiconductor devices. [Explanation of Symbols]

[0121] 1: Package substrate 100: Optoelectronic devices 11: Bottom 13:Cylinder part 2: Light-emitting element 21: Exit surface 3: Transparent lid 41: First Optical Interference Filter 42: Second optical interference filter 43: Third Optical Interference Filter 44: Fourth Optical Interference Filter 45: Fifth Optical Interference Filter 46: Sixth Optical Interference Filter 9: Adhesive layer A: Fiber probe P: Central part R1: First area R2: Second area R3: Third area R4: Fourth area R5: Fifth area R6: Sixth area 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 wavelength that is placed on the surface of the transparent lid and has a transmittance of 50% at an incident angle of 0 degrees is defined as the specific wavelength λ. １ The first optical interference filter is, The transparent lid is placed on the surface of the transparent lid, and the wavelength at which the transmittance is 50% at an incident angle of 0 degrees is λ ２ (However, λ １ <λ ２ It comprises a second optical interference filter, The light-emitting element is an ultraviolet LED with a light emission center wavelength of 300 nm or more and 350 nm or less. The specified wavelength is a wavelength shorter than the emission center wavelength of the light-emitting element, and is within the range between the emission center wavelength of the light-emitting element and the maximum wavelength in the wavelength range to be cut off. The first optical interference filter is arranged in a first region that includes a position overlapping with the central part of the emission surface when viewed in the vertical direction. The aforementioned second optical interference filter is located in a second region adjacent to the outside of the first region when viewed in the vertical direction.

2. The ejection surface is formed in a planar shape, and the perpendicular direction of the ejection surface coincides with the vertical direction. If θ is the angle of inclination of the light ray that is obliquely directed away from directly above the emission surface, with respect to the perpendicular line from the outer circumference of the emission surface toward the transparent lid, In the aforementioned second optical interference filter, the wavelength at which the transmittance is 50% is λ １ The angle of incidence is α ２ In this case, the inner circumference of the second region is (α ２ -5°) ≤ θ ≤ α ２ The optical semiconductor device according to claim 1, wherein the range is such that the inner circumference of the second region is the outer circumference of the first region.

3. 5° ≤ α ２ The optical semiconductor device according to claim 2, wherein 40° ≥ α ≥ 5°

4. The inner circumference of the second optical interference filter is the inner circumference of the second region, The outer periphery of the first optical interference filter is within the range of the second region, The optical semiconductor device according to claim 2 or 3, wherein, in the direction view of the aforementioned tilt angle, a portion of the first optical interference filter and a portion of the second optical interference filter overlap.

5. The optical semiconductor device according to any one of claims 1 to 4, wherein the first optical interference filter is disposed on the surface of the transparent lid facing the light-emitting element, and the second optical interference filter is disposed on the surface of the transparent lid opposite to the surface facing the light-emitting element.

6. The transparent lid is placed on the surface of the transparent lid, and the wavelength at which the transmittance is 50% at an incident angle of 0 degrees is λ ３ (However, λ ２ <λ ３ It is equipped with a third optical interference filter, The optical semiconductor device according to any one of claims 1 to 5, wherein the third optical interference filter is located in a third region adjacent to the outside of the second region in a vertical view.

7. The ejection surface is formed in a planar shape, and the perpendicular direction of the ejection surface coincides with the vertical direction. If θ is the angle of inclination of the light ray that is obliquely directed away from directly above the emission surface, with respect to the perpendicular line from the outer circumference of the emission surface toward the transparent lid, In the third optical interference filter, the wavelength at which the transmittance is 50% is λ １ The angle of incidence is α ３ (However, α ３ >α ２ In the case where the inner circumference of the third region is (α ３ -5°) ≤ θ ≤ α ３ The optical semiconductor device according to claim 6, wherein the range is such that the inner circumference of the third region is the outer circumference of the second region.

8. The inner circumference of the third optical interference filter is the inner circumference of the third region, The outer periphery of the second optical interference filter is within the range of the third region which is outside the second region, The optical semiconductor device according to claim 7, wherein, in the direction view of the aforementioned tilt angle, a portion of the second optical interference filter and a portion of the third optical interference filter overlap.

9. Said λ １ The optical semiconductor device according to any one of claims 1 to 8, wherein the wavelength is 3 nm or more and 10 nm shorter than the emission center wavelength of the light-emitting element.

Images