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 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; a first filter 41 which is arranged on an upper surface side of the light emitting element 2 and is an optical interference type light cut filter having a transmittance of 50% or less at a specific wavelength or less; and a second filter 42 which is arranged on the emission surface 21 or a surface of the transparent lid 3 and is an optical cut filter of a type different from that of the first filter 41.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, or optical cut filters, that cut wavelengths below a specific wavelength include those that utilize optical coherence using dielectric thin films, such as single-layer or multi-layer films, and those that, unlike those that utilize optical coherence, utilize resonance phenomena caused by the material. Optical cut filters that utilize optical coherence (hereinafter referred to as optical interference filters) can reduce the wavelength difference between the wavelength at which the transmittance is 90% and the wavelength at which the transmittance is 10%, making them effective when it is desired to cut 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. On the other hand, while optical cut filters that are not optical interference filters have the advantage that the transmittance does not change with the angle of incidence of light, it has been difficult to reduce the wavelength difference between the wavelength at which the transmittance is 90% and the wavelength at which the transmittance is 10%.

[0009] Therefore, there is a need for an optoelectronic device that incorporates a point light source, such as an LED chip, and can suppress the attenuation of the output of light on the longer wavelength side of a specific wavelength while cutting off light on the shorter wavelength side of a specific wavelength.

[0010] This invention has been made in view of the above circumstances, and its purpose is to provide an optical semiconductor device that can cut off light on the shorter wavelength side while suppressing the attenuation of the output of light on the longer wavelength side of 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, A first filter, which is an optical interference type optical cut filter disposed on the exit surface or the surface of the transparent cover and has a transmittance of 50% or less at a specific wavelength or less, A second filter, which is an optical cut filter of a different type from the first filter and is disposed on the surface of the transparent cover.

Advantages of the Invention

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

Brief Description of the Drawings

[0013] [Figure 1] It is a top view of an optical semiconductor device according to the first embodiment. [Figure 2] It is a cross-sectional view of an optical semiconductor device according to the first embodiment. [Figure 3] It is a graph showing an example of the transmittance spectrum of the first filter. [Figure 4] It is an explanatory diagram of a method for measuring the light distribution characteristics. [Figure 5] It is a cross-sectional view of an optical semiconductor device according to the second embodiment. [Figure 6] It is a cross-sectional view of an optical semiconductor device according to the third embodiment. [Figure 7] It is a graph showing an example of the transmittance spectrum of the second filter. [Figure 8] It is a diagram showing the emission spectrum of Example 1. [Figure 9] It is the light distribution characteristics of wavelengths 306 nm to 400 nm in Example 1. [Figure 10] It is the light distribution characteristics of wavelengths 200 nm to 305 nm in Example 1. [Figure 11] It is the light distribution characteristics of wavelengths 200 nm to 305 nm in Comparative Example 1. [Figure 12] It is an enlarged view of wavelengths 295 to 320 nm in the emission spectra of the examples and the comparative example. [Modes for carrying out the invention]

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

[0015] (First Embodiment) Figure 1 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 1).

[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 Figure 2 and subsequent figures and in other embodiments. For example, the side of the transparent lid 3 on the light-emitting element 2 side will be referred to as the bottom surface, and the side of the transparent lid 3 opposite 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 of these surfaces. In this embodiment, a top view refers to a view of the transparent lid 3 from above in the thickness direction of the transparent lid 3, with the top surface of the transparent lid 3 viewed from above. 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.

[0017] 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. In Figure 2, the virtual line of emitted light corresponding to an inclination angle θ of 20° is shown as θ. 20The symbols indicate this. Note that Figure 2 is a schematic diagram, and therefore the optical path of the light emitted from the emission surface 21 and taken out of 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 filter 41 or the second 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 filter 41 or the second filter 42, respectively. When designing the placement of the optical interference filters, this deviation may be taken into consideration or it may be simplified and ignored. In the description of this embodiment, a straight line is assumed, ignoring the deviation.

[0018] As shown in Figure 2, the optical semiconductor device 100 comprises a package substrate 1, a light-emitting element 2 positioned on the upper surface of the package substrate 1 with its output surface 21 (the side that extracts light) facing upwards, a transparent cover 3 that forms a closed space S between itself and the package substrate 1 and covers the light-emitting element 2, a first filter 41 which is an optical interference type light cut filter positioned on the upper surface of the light-emitting element 2 or the surface of the transparent cover 3 (the lower surface of the transparent cover 3 in Figure 2) and has a transmittance of 50% or less for wavelengths below a specific wavelength λ1, and a second filter 42 which is an optical cut filter of a different type from the first filter 41 and is positioned on the surface of the transparent cover 3 (the upper surface of the transparent cover 3 in Figure 2).

[0019] 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 either the first filter 41 or the second filter 42, and light with wavelengths shorter than λ1 is cut off. Both the first filter 41 and the second filter 42 are high-pass filters.

[0020] 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.

[0021] As shown in Figure 1, the shape of the first filter 41 in a top view is a shape that includes the region overlapping with the exit surface 21, and its shape can be selected from shapes such as a square, rectangle, polygon, or circle. The shape of the second filter 41 in a top view does not need to include the region overlapping with the exit surface 21, and an annular shape is preferable. As shown in Figure 1, the outer circumference of the first filter 41 and the inner and outer circumferences of the second filter 42 can be similar in shape to the exit surface 21. In addition, although not shown, the outer circumference of the first filter 41 and the inner and outer circumferences of the second filter 42 may have a radius of curvature at the corners such that they are at a certain distance from the outer circumference of the exit surface 21.

[0022] (Explanation of each part) The following describes in detail each part of the optoelectronic device 100. 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 a emission center wavelength between 300 nm and 350 nm, for example. The emission surface 21 of the light-emitting element 2 is formed in a planar shape. The vertical direction (direction along the perpendicular line) of the emission surface 21 is the vertical direction of the optoelectronic device 100. 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 light-emitting element 2 is considered to be square in a top view. The light-emitting element 2 is equipped with electrodes and the like (not shown).

[0023] 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.

[0024] 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. The package substrate 1 is equipped with electrodes and the like (not shown) and is electrically connected to the light-emitting element 2. 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.

[0025] 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).

[0026] 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. That is, 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 while positioned between the bottom surface 11 of the package substrate 1 and the transparent lid 3. 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.

[0027] 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.

[0028] The area of ​​the transparent cover 3 that overlaps with the emission surface 21 in a top view is planar and parallel to the emission surface 21 of the light-emitting element 2 in cross-section.

[0029] Furthermore, as will be described later, when the first filter 41 and the second filter 42 are placed on the surface of the transparent lid 3, the surface of the transparent lid 3 in the area where the first filter 41 and the second filter 42 are placed is made flat. The surface roughness of the transparent lid 3 is arbitrary, as long as it does not interfere with the placement of the first filter 41 and the second filter 42.

[0030] 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.

[0031] The first filter 41 is an optical cut filter that utilizes optical coherence. The first filter 41 is a laminate of two or more dielectric layers with different refractive indices (for example, two or three types). In the first filter 41, it is preferable to repeatedly laminate the 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 greater the number of pairs, the better the steepness of the transmittance near λ1 as a specific wavelength can be made. In this embodiment, as shown in Figure 3, the first filter 41 is a high-pass filter that sets the transmittance at a predetermined wavelength or less (short wavelength side) at a predetermined incident angle (for example, 0°) to 50% or less. In Figure 3, the "filter transmittance" on the vertical axis is the light transmittance of the first filter 41. The wavelength dependence (transmission spectrum) of the transmittance of the first filter 41 can be measured using a spectrophotometer (for example, 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.

[0032] When the first filter 41 shown in Figure 2 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 first filter 41 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. These layers can be deposited by known methods such as vacuum deposition, sputtering, or CVD. The first filter 41 is formed in a predetermined area using photolithography.

[0033] The characteristics of the first filter 41, 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 the first filter 41 has an SiO2 layer and a TiO2 layer will be described below 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 the first filter 41. 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.

[0034] [Table 1]

[0035] In the following explanation, the case where λ1 is 305 nm will be used as an example. λ1 is set to reduce the light output in the wavelength range to be cut off within a range between the emission center wavelength of the light-emitting element 2 (in this embodiment, the case of 310 nm will be explained as an example) and the maximum wavelength within the wavelength range to be cut off (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.

[0036] In the following, the incident angle at which the wavelength λ1 results in a 50% transmittance in the first filter 41 is referred to as the optimal angle α. In the optical interference filter shown in Figure 3, which illustrates an example of the transmission spectrum of the first filter 41, 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°. In other words, the optimal angle α in this embodiment is 0°. In the first filter 41, 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 the first filter 41 is 0° ≤ α ≤ 20°.

[0037] As shown in Figures 1 and 2, in this embodiment, the light cut filter includes a first filter 41 and a second filter 42. The first filter 41 can be placed on the top surface of the light-emitting element 2 or on the surface of the transparent lid 3, and can be in any position as long as it encloses the entire emission surface 21 of the light-emitting element 2 when viewed from above. For example, it may be on the top or bottom surface of the transparent lid 3, or it may be placed in contact with the emission surface 21 of the light-emitting element 2. The second filter 42 is installed on the surface of the transparent lid 3. It may be installed on the top or bottom surface of the transparent lid 3. In Figure 2, an example is shown in which the first filter 41 is placed on the bottom surface of the transparent lid 3 and the second filter 42 is placed on the top surface of the transparent lid 3.

[0038] By forming the first filter 41 and the second filter 42 on different surfaces of the transparent lid 3, as shown in Figure 2, rather than on the same surface, the range of incident angles (inclination angle from the exit surface 21) handled by each light cut filter can be widened, thereby appropriately suppressing the attenuation of light output on the wavelength side longer than λ1, which is a specific wavelength. In addition, the installation of each light cut filter on the transparent lid 3 and the formation of the top view shape using photolithography, etc., become easier, and the manufacturing of the optoelectronic device 100 becomes easier.

[0039] Figure 2 shows a case where, in a directional view at an inclination angle from the outer circumference of the emission surface 21, parts of the first filter 41 and the second filter 42 overlap, and the outer circumference of the first filter 41 is outside the inner circumference of the second filter 42. By overlapping the light cut filters in this way in a directional view at a predetermined inclination angle, the allowable range of errors in the placement of the light cut filters is expanded, while eliminating the gap between the first filter 41 and the second filter 42 for the light radiated from the emission surface 21. This makes it possible to suppress the attenuation of the output of light on the wavelength side longer than λ1, which is a specific wavelength, while avoiding a decrease in the performance of cutting light on the wavelength side shorter than λ1.

[0040] Consider the case where an optical interference filter having the transmittance characteristics shown in Figure 3 is formed, for example, on the entire lower surface of the transparent lid 3. Directly above the emission surface 21 of the light-emitting element 2, the incident angle of light rays incident on the lower surface of the transparent lid 3 from the emission surface is often near 0°. Therefore, for light incident on the first filter with an optimal angle α=0° at an incident angle near 0°, light in the wavelength band below λ1 can be effectively cut. For example, at an incident angle of 35° in Figure 3, the transmittance of the maximum wavelength (300nm) in the wavelength range to be cut is close to 100%, and at an incident angle of 15° in Figure 3, the transmittance of the maximum wavelength (300nm) in the wavelength range to be cut is less than 10%.

[0041] In other words, in an optical interference filter as shown in Figure 3, light with wavelengths shorter than λ1 that is incident at a large angle of inclination relative to the first filter 41 (for example, an incident angle of 20° as shown in Figure 3) cannot be sufficiently cut by the first filter 41 and will pass through the first filter 41. In particular, the transmittance becomes high in the wavelength range close to λ1, even on the wavelength side shorter than λ1. Thus, in order to cut the light with wavelengths shorter than λ1 that is not cut by the first filter 41 because it is incident at a large angle of inclination relative to the first filter 41, the optical semiconductor device 100 of this embodiment has a second filter 42 in addition to the first filter 41. By providing a second filter for light with wavelengths shorter than λ1 that would pass through the first filter 41 in a range away from directly above the output surface 21, light in the wavelength band below λ1 can be effectively cut. It is preferable that the transmittance of the second filter 42 is 50% or less for a specific wavelength below λ1, similar to the first filter 41. When using an optical interference filter as shown in Figure 3 as the first filter, the range in which it is preferable to provide the second filter is when the inclination angle θ from the outer circumference of the output surface 21 is 15° or more. In the incident angle-dependent characteristics of the transmission spectrum of the first filter 41, it is preferable to position the second filter 42 in a range of tilt angle equal to or greater than the incident angle at which the transmittance of the maximum wavelength in the wavelength range to be cut becomes 10% or less.

[0042] The arrangement conditions for the first filter 41 and the second filter 42 are as follows. The first filter 41 is positioned on the exit surface 21 or on the surface of the transparent cover 3. It is preferable that the first filter 41 is positioned in a range that includes at least a position overlapping with the emission surface 21 in a top view. The second filter 42 is positioned on the surface of the transparent lid 3. It is preferable that the second filter 42 is positioned so as not to include any position that overlaps with the emission surface 21 in a top view.

[0043] If the above arrangement conditions are met, in order to cut out light in the wavelength band below λ1, it is permissible for the first filter 41 to cover an area other than the position that overlaps with the output surface 21 when viewed from above. Here, in order to suppress the attenuation of the output of light on the wavelength side longer than λ1, it is preferable that the second filter 42 does not cover the area directly above the output surface 21. That is, it is preferable that the second filter 42 be formed in an annular shape that surrounds the outer circumference of the output surface 21 so as not to include the position that overlaps with the output surface 21 when viewed from above. This is because, compared to the first filter 41, the second filter 42 cannot reduce the wavelength difference between the wavelength at which the transmittance is 90% and the wavelength at which the transmittance is 10%, so even if the λ1 of the first filter 41 and the second filter 42 are matched so that the transmittance of the second filter 42 on the wavelength below a specific wavelength λ1 is 50% or less, a portion of the light on the wavelength side longer than λ1 that has passed through the first filter will be cut off by the second filter 42. Therefore, it is preferable that the inner circumference of the area where the second filter 42 is placed does not include any position that overlaps with the exit surface 21 in a top view, and that the inclination angle θ of the inner circumference of the second filter 42 (the outer circumference of the area where the second filter 42 is not provided) from the outer circumference of the exit surface 21 is, for example, between 15° and 30°.

[0044] The second filter 42 is a light cut filter of a different type than the first filter 41, which is an optical interference type light cut filter. The second filter 42 can be made of, for example, metal oxide films such as ITO films or TiO2 films (e.g., vapor-deposited films), plastic films such as cellophane, vinylidene chloride, and polyester, glass doped with metal oxides such as TiO2 or Fe2O3, or Al, which allows for the intentional design of the energy level of the absorption edge in the ultraviolet wavelength range. x1 Ga x2 In 1-x1-x2 N(0≦x1≦1, 0≦x2≦1, 0≦x1+x2≦1) film and Zn y Mg 1-yA film such as O(0≦y≦1) can be used. Such a non-optical interference type optical cut filter can attenuate the output of light on the short wavelength side of λ1, as a specific wavelength, regardless of the angle of incidence of light (the inclination angle θ from the outer circumference of the output surface in Figure 2), as long as it has sufficient thickness along the direction of light transmission with respect to the wavelength of the incident light. Furthermore, as an optical cut filter that can be used as the second filter 42, for example, an optical cut filter (optical filter) made by mixing tin-doped indium oxide (F-ITO manufactured by Dowa Mining Co., Ltd.), as described in Japanese Patent Application Publication No. 2003-336034, with acrylic resin is known.

[0045] The second filter 42, formed from materials such as those listed above, has a lower transmittance on the wavelength side longer than λ1 compared to the first filter 41. While it cannot reduce the wavelength difference between the wavelength at which the transmittance is 90% and the wavelength at which the transmittance is 10%, it can have a characteristic where the transmittance of light below the maximum wavelength (300 nm) in the wavelength range to be cut is close to 0%. In other words, it can cut out light on the wavelength side shorter than λ1 as a specific wavelength, and is therefore suitable for use as the second filter 42 in this embodiment. The wavelength λ2 at which the transmittance of the specific wavelength in the second filter 42 is 50% can be determined based on the required specifications for the filter characteristics of the optoelectronic device 100, taking into account the respective transmittance characteristics of the first filter 41 and the second filter 42, the beam angle characteristics of the LED chip and SMD, and the filter arrangement range. It is desirable that it is close to the specific wavelength λ1 in the first filter 41. For example, it is preferable that it is within the range of λ1-5≦λ2≦λ1+5, and most preferably λ1=λ2.

[0046] In the optoelectronic device 100, the extent to which light with wavelengths longer than λ1 is efficiently extracted to the outside of the optoelectronic device 100 while light with wavelengths shorter than λ1 is appropriately cut off can be determined, for example, by examining the light distribution characteristics of the light emitted from the optoelectronic device 100.

[0047] The light distribution characteristics can be measured, for example, as follows. FIG. 4 shows an explanatory diagram of a method for measuring the light distribution characteristics of the optical semiconductor device 100 according to the present embodiment. A fiber probe A is disposed at a position 100 mm away from the optical semiconductor device 100, and by changing the observation angle at the tip position of the fiber probe A, the light distribution characteristics as the observation angle dependency of the light emitted from the optical semiconductor device 100 can be examined. 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 is connected to a spectroscope (for example, QE65 Pro manufactured by Ocean Optics) to measure the emission spectrum. For example, the fiber probe A may be fixed and the optical semiconductor device 100 may be rotated to measure the light distribution characteristics.

[0048] (Example 1) The optical semiconductor device 100 as illustrated in FIG. 2 was configured as follows to be an optical semiconductor device according to the example. In the following description, the description regarding dimensions is the value in the cross section shown in FIG. 2.

[0049] The transparent lid 3 was made of sapphire and had a plate thickness of 350 μm. The light emitting element 2 employed an LED chip having a thickness of 0.44 mm and a size of 1 mm × 1 mm, and the distance from the emission surface 21 to the lower surface of the transparent lid 3 was 0.135 mm. The emission center wavelength of the light emitting element 2 was 310 nm. The package substrate 1 was made of AlN ceramics, and the distance from the side surface of the light emitting element 2 to the inner side surface in the recess of the package substrate 1 was 0.65 mm. The width of the adhesive layer 9 between the transparent lid 3 and the package substrate 1 was 0.6 mm.

[0050] The above-described optical interference filter (optimal angle 0°) shown in FIGS. 3 and Table 1 was used for the first filter 41, and an Al 0.3 Ga 0.7 N film was formed to a thickness of 0.4 μm using a MOCVD apparatus. The transmission spectrum of the Al 0.3 Ga 0.7 N film formed on the sapphire substrate is shown in FIG. 7.

[0051] In Example 1, as shown in Figure 2, the inner circumference of the second filter 42 (the outer circumference in the area where the second filter 42 is not provided) is at a tilt angle θ of 20° from the outer circumference of the emission surface 21, and the outer circumference of the second filter 42 is at the position of the outer circumference of the transparent cover 3. Also, the outer circumference of the first filter 41 is at a tilt angle of 40°. In this way, the optical semiconductor device 100 of Example 1 was obtained.

[0052] Figure 8 shows the emission spectra of this embodiment 1 with and without the first filter 41 and the second filter 42. The emission spectra were measured using a spectrometer to measure the total luminous flux with an integrating sphere.

[0053] In this embodiment 1, with and without the first filter 41 and the second filter 42, the optical semiconductor device 100 was fixed, and the fiber probe A was rotated in 5° increments from -60° to 60° to measure the light distribution characteristics. For example, targeting wavelengths between 200 nm and 400 nm, the values ​​for 306-400 nm and 200 nm-305 nm were extracted from the obtained data, and the effects of the present invention were evaluated by comparing the presence or absence of the first filter 41 and the second filter 42. The results are shown in Figures 9 and 10.

[0054] (Example 2) An optoelectronic device 100 according to Example 2 was obtained in the same manner as in Example 1, except that the inner circumference of the second filter 42 (the outer circumference in the area where the second filter 42 is not provided) was changed to a position where the inclination angle θ from the outer circumference of the emission surface 21 is 25°.

[0055] (Comparative Example 1) A photoelectronic semiconductor device 100 according to Comparative Example 1 was obtained in the same manner as in Example 1, except that only the first filter illustrated in Figure 3 was placed on the entire lower surface of the transparent lid 3, and there was no second filter.

[0056] Figure 11 shows the optical distribution characteristics at wavelengths of 200 nm to 305 nm for a comparative example and for a configuration without both the first and second filters.

[0057] Figure 11 shows that when only the first filter is placed across the entire surface of the transparent lid 3 and there is no second filter, the ability to reduce the intensity of light on the wavelength side shorter than λ1 is greatly reduced at angles where the absolute value of the beam angle is greater than 15°. In this embodiment, because a second filter is placed, the intensity of light on the wavelength side shorter than λ1 can be reduced even further at angles where the absolute value of the beam angle is greater than 15°, compared to the case shown in Figure 11 where there is no second filter.

[0058] (Comparative Example 2) A photoelectronic semiconductor device 100 according to Comparative Example 1 was obtained in the same manner as in Example 1, except that only the second filter shown in Figure 7 was formed on the entire lower surface of the transparent lid 3, and the first filter was absent.

[0059] Figure 12 shows magnified views of the emission spectrum for wavelengths 295-320 nm in Examples 1 and 2, Comparative Examples 1 and 2, and the case without a filter. In this example, it can be seen that the attenuation of light output on the wavelength side longer than the specific wavelength of 305 nm is suppressed compared to Comparative Example 2, while light on the wavelength side shorter than the specific wavelength can be cut off more significantly compared to Comparative Example 1.

[0060] (Second embodiment) In the first embodiment described above, the case in which the optical cut filter is installed on the lower surface of the transparent cover 3 in the optical semiconductor device 100 was illustrated and explained as shown in Figure 2. However, the arrangement of the optical cut filter is not limited to the above embodiment, and for example, as shown in the cross-sectional view of Figure 5 (showing the same cross-section as in Figure 2), the first filter 41 may be directly placed on the emission surface 21.

[0061] Figure 5 shows the case where the first filter 41 is directly placed on the emission surface 21 and the second filter 42 is placed on the upper surface of the transparent lid 3. By arranging the first filter 41 in this way, it is possible to avoid a decrease in performance in cutting 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, as in the first embodiment. It is also preferable, as in the first embodiment, in that the first filter 41 is placed closer to the light-emitting element 2, and light with an incident angle close to perpendicular from the emission surface 21 can be efficiently filtered.

[0062] (Third embodiment) In the first embodiment described above, the optical semiconductor device 100 comprises a first filter 41 and a second filter 42, with the first filter 41 positioned on the lower surface of the transparent cover 3 and the second filter 42 on the upper surface of the transparent cover 3, as illustrated and explained in Figure 2. In the second embodiment described above, the second filter 42 is positioned on the upper surface of the transparent cover 3, and the first filter 41 is formed directly on the emission surface 21. However, the arrangement of the light cut filters is not limited to the above embodiments, and for example, as shown in the cross-sectional view of Figure 6, these light cut filters may be arranged in a stacked manner on one side of the transparent cover 3 (the upper surface of the transparent cover in Figure 6).

[0063] Light incident at an angle that cannot be cut by the first filter 41 passes through the first filter 41 without sufficient filtering of light with wavelengths shorter than λ1, but the subsequent second filter 42 cuts off the light with wavelengths shorter than λ1.

[0064] In this way, by arranging the second filter 42 to overlap the upper surface of the first filter 41, the formation of the first filter 41 and the second filter 42 on the transparent cover 3 becomes easier, thereby facilitating the manufacture of the optoelectronic device 100.

[0065] As described above, an optoelectronic semiconductor device can be provided.

[0066] The configurations disclosed in the first to third embodiments described above are illustrative examples, and the embodiments of the present invention are not limited thereto. They can be modified as appropriate without departing from the purpose of the present invention. [Industrial applicability]

[0067] This invention can be applied to optical semiconductor devices. [Explanation of Symbols]

[0068] 1: Package substrate 100: Optoelectronic devices 11: Bottom 13:Cylinder part 2: Light-emitting element 21: Exit surface 3: Transparent lid 41: First filter 42: Second filter 9: Adhesive layer A: Fiber probe P: Central part 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, A first filter, which is an optical interference type light cut filter, is placed on the aforementioned emission surface or on the surface of the transparent lid and has a transmittance of 50% or less below a specific wavelength. The transparent lid is disposed on the surface of the transparent lid and comprises a second filter, which is a light-cutting filter of a different type than the first filter, The first filter is a laminate of two or more dielectric layers with different refractive indices. The second filter is selected from an ITO film, a plastic film or a metal oxide-doped glass film, an Al x1 Ga x2 In 1-x1-x2 N (0 ≤ x1 ≤ 1, 0 ≤ x2 ≤ 1, 0 ≤ x1 + x2 ≤ 1) film, and a Zn y Mg 1-y O (0 ≤ y ≤ 1) film, in an optoelectronic device.

2. 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, A first filter, which is an optical interference type light cut filter, is placed on the aforementioned emission surface or on the surface of the transparent lid and has a transmittance of 50% or less below a specific wavelength. The transparent lid is disposed on the surface of the transparent lid and comprises a second filter, which is a light-cutting filter of a different type than the first filter, An optoelectronic device that is an ultraviolet LED with a emission center wavelength of 300 nm to 350 nm.

3. 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, A first filter, which is an optical interference type light cut filter, is placed on the aforementioned emission surface or on the surface of the transparent lid and has a transmittance of 50% or less below a specific wavelength. The transparent lid is disposed on the surface of the transparent lid and comprises a second filter, which is a light-cutting filter of a different type than the first filter, An optoelectronic semiconductor device in which the specified wavelength is 3 nm to 10 nm shorter than the emission center wavelength of the light-emitting element.

4. The first filter is positioned on the lower surface of the transparent lid, The optoelectronic device according to any one of claims 1 to 3, wherein the second filter is disposed on the upper surface of the transparent lid.

5. The optical semiconductor device according to any one of claims 1 to 4, wherein the first filter is arranged such that it includes a position overlapping with the output surface when viewed from above, and the second filter is arranged such that it does not include a position overlapping with the output surface when viewed from above.

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