JP2017130587A - Ultraviolet light emitting device and device having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultraviolet light emitting device that is excellent in durability and has a high light extraction efficiency.SOLUTION: The ultraviolet light emitting device includes an ultraviolet light emitting element 3 having a substrate 3a and a nitride semiconductor layer 3b, a joint substrate 2 which has an upper surface disposed to face a surface of the substrate 3a on which the nitride semiconductor layer 3b is provided, and is electrically connected to the ultraviolet light emitting element 3, a housing 4 having a connection wiring 4a, a wire 5 for electrically connecting the joint substrate 2 and the connection wiring 4a, a first resin layer 6 for sealing at least a part of the wire 5, and a second resin layer 7 which is provided on an upper layer of the first resin layer 6 and has a characteristic different from that of the first resin layer 6. For example, the first resin layer 6 having a lower ultraviolet transmittance is denatured by ultraviolet rays, thereby avoiding occurrence of disconnection or the like in the wire 5. Ultraviolet rays radiated from the upper portion of the side surface of the nitride semiconductor layer 3b is taken out by the second resin layer 7 having a higher ultraviolet transmittance, thereby enhancing the light extraction efficiency.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an ultraviolet light emitting device and a device including the same.

A semiconductor device based on a nitride substrate is expected to be applied to a light emitting device that emits light, a light receiving device that receives light, and a power device by taking advantage of its wide band gap. In particular, a semiconductor light emitting device having an aluminum nitride (AlN) substrate can emit deep ultraviolet light having a wavelength of 280 nm or less, and has a high output and long life deep ultraviolet LED (UVC-LED: usable for sterilization applications). The development is expected to lead to UltraViolet C-Light Emitting Diode).
Various packaging methods for ultraviolet light emitting devices, which are semiconductor light emitting devices capable of emitting deep ultraviolet light, are known, and there is a technology disclosed in Patent Document 1, for example, as a conventional technology.

JP 2005-277441 A

Patent Document 1 discloses a technique related to a package in which a semiconductor light emitting device is flip-chip mounted. In Patent Document 1, an LED flip-chip mounted on a mounting substrate is provided on the substrate, and electrical connection between the mounting substrate and the substrate is ensured by wire bonding. Thereafter, the whole is sealed with resin.
When this package technology is applied to the ultraviolet LED, there is a possibility that the resin is cured by the ultraviolet ray emitted from the LED and the wire is disconnected. Further, when resin sealing is not performed, there is a problem that light extraction is reduced.

  This invention is made | formed in view of such a situation, Comprising: It aims at providing the ultraviolet-ray light-emitting device excellent in durability and high light extraction efficiency.

An ultraviolet light-emitting device according to an embodiment of the present invention includes an ultraviolet light-emitting element including a substrate having a nitride semiconductor layer on one surface, and an upper surface facing a surface of the substrate having the nitride semiconductor layer. A bonding substrate electrically connected to the ultraviolet light emitting element, a housing having a connection wiring for external connection, a wire for electrically connecting the bonding substrate and the connection wiring, and at least the A first resin layer that seals a part of the wire, and a second resin layer that is provided in an upper layer of the first resin layer and has different characteristics from the first resin layer are provided.
An apparatus according to one embodiment of the present invention includes the ultraviolet light-emitting device according to the above aspect.

  According to one embodiment of the present invention, an ultraviolet light-emitting device that has excellent durability and high light extraction efficiency can be realized.

It is sectional drawing which shows the structure of the ultraviolet-ray light-emitting device concerning one Embodiment of this invention. It is sectional drawing which shows the structure of the ultraviolet-ray light-emitting device concerning other embodiment of this invention.

  Hereinafter, an embodiment for carrying out the present invention will be described. This embodiment exemplifies a configuration for embodying the technical idea of the present invention, and does not specify the material, shape, structure, arrangement, dimensions, and the like of each part as follows. The technical idea of the present invention can be variously modified within the technical scope defined by the claims described in the claims.

<Ultraviolet light emitting device>
An ultraviolet light emitting device according to an embodiment of the present invention includes an ultraviolet light emitting element including a substrate having a nitride semiconductor layer on one surface, and an upper surface facing the surface of the substrate having the nitride semiconductor layer. A bonding substrate that is disposed and electrically connected to the ultraviolet light emitting element, a housing having connection wiring for external connection, a wire that electrically connects the bonding substrate and the connection wiring, and at least a part of the wire; A first resin layer to be sealed; and a second resin layer provided on an upper layer of the first resin layer and having different characteristics from the first resin layer.

The ultraviolet light emitting device according to an embodiment of the present invention employs resins having different functions for the first resin layer for sealing the wire and the second resin layer for sealing the upper part of the side surface of the nitride semiconductor layer. be able to. By adopting a resin having excellent durability against ultraviolet rays as the first resin layer, it is possible to prevent the wires in the first resin layer from being disconnected due to stress or the like as the resin is cured by ultraviolet rays, thereby improving durability. It becomes possible. In addition, by adopting a resin with excellent ultraviolet transparency as the second resin layer, it becomes possible to take out ultraviolet rays emitted from the upper part of the side surface of the nitride semiconductor layer, thereby improving the light extraction efficiency. Can do.
Next, each component of the ultraviolet light emitting device according to the embodiment of the present invention will be described. The characteristics of each constituent element of the ultraviolet light emitting device described below can be applied individually or in combination without departing from the technical idea of the present invention.

<Joint substrate>
In the ultraviolet light emitting device according to an embodiment of the present invention, the bonding substrate is not particularly limited as long as it can be electrically connected to an ultraviolet light emitting element described later. As the bonding substrate, an insulating substrate as a base material and a substrate mainly made of a ceramic material can be used. Examples of the bonding substrate include an alumina substrate and an aluminum nitride substrate, and a material having high thermal conductivity is preferable. The bonding substrate has electrodes for forming an electric circuit on the surface or inside, or on the surface and inside, and any electrode material may be used as long as it has conductivity. For example, silver or tungsten is mainly used. Examples include paste as a component, gold, copper, nickel, titanium, cobalt and the like formed by plating, vapor deposition, and sputtering. The bonding method between the electrode of the bonding substrate and the ultraviolet light emitting element described later is not particularly limited, but solder material or gold / gold bonding is preferable. As an example, the conductive wiring formed on the surface and inside of the bonding substrate, and a part of an n-type nitride semiconductor layer and a part of a p-type nitride semiconductor layer of an ultraviolet light emitting element described later are electrically connected. Connection form. For the connection between the two, for example, flip chip connection using an Au ball or the like can be performed, but the present invention is not particularly limited to this.

<Ultraviolet light emitting device>
In the ultraviolet light emitting device according to an embodiment of the present invention, the ultraviolet light emitting element includes a substrate having a first main surface and a second main surface, and a nitride semiconductor layer formed on the first main surface. The bonding substrate and the first main surface are arranged on the bonding substrate so as to be electrically connected to the bonding substrate. Here, “the bonding substrate and the first main surface face each other” means that the surface forming the surface of the bonding substrate and the surface forming the first main surface of the substrate of the ultraviolet light emitting element are substantially parallel. .
The substrate included in the ultraviolet light emitting element is not particularly limited as long as it has a first main surface and a second main surface and a nitride semiconductor layer can be formed on the first main surface, and sapphire (Al ₂ O ₃ ), oxide single crystal substrates such as spinel (MgAl ₂ O ₄ ), zinc oxide (ZnO), magnesium oxide (MgO), and substrates such as Si, SiC, GaAs, GaP, AlN, and GaN may be used. it can. The substrate included in the ultraviolet light emitting element may further have a buffer layer having the same composition or a different composition in addition to the substrate materials listed above. For example, a substrate having an aluminum nitride buffer layer on sapphire also becomes a substrate as a whole. Further, when the original substrate is removed in a later process, the remaining buffer layer becomes the substrate.

The plane orientation of the substrate is not particularly limited, and may be a just substrate or a substrate provided with an off angle. Further, the thickness of the substrate is not particularly limited, and an appropriate thickness that is not less than the thickness that can be handled can be used.
The nitride semiconductor layer is formed on the first main surface of the substrate. The nitride semiconductor layer may be a layer including an n-type nitride semiconductor layer, a light emitting layer, and a p-type nitride semiconductor layer. In addition to the n-type nitride semiconductor layer, the light-emitting layer, and the p-type nitride semiconductor layer, a contact layer for realizing good ohmic contact with the electrode, and a barrier layer (block layer for improving luminous efficiency) And other layers may be further provided. The light emitting layer preferably has a single or multiple quantum well structure in order to improve the light emission efficiency. As a material used for the nitride semiconductor layer, various materials can be adopted according to the emission wavelength of the LED. As an example, a III-V group compound semiconductor material represented by InAlGaN or AlGaInP can be used.

A nitride semiconductor layer that emits ultraviolet light having a central emission wavelength of 230 nm to 320 nm when a preset voltage is applied can be applied. Ultraviolet LEDs that emit ultraviolet light having a wavelength of 230 nm or more and 320 nm or less can be applied to various applications such as sterilization and separation of protein components.
The n-type nitride semiconductor layer may have a plurality of layers composed of, for example, InAlGaN or AlGaInP. At least a part of the plurality of layers is preferably distorted in a pseudo-lattice matching so as to approach the lattice parameter of the light emitting layer. Alternatively, the n-type nitride semiconductor layer may include one layer or a plurality of layers of InAlGaN or AlGaInP. A composition in which the composition of InAlGaN or AlGaInP changes with the thickness of the n-type nitride semiconductor layer, that is, a composition that changes linearly or stepwise along the thickness direction may be used.

As an impurity used for doping, magnesium (Mg) is exemplified as a p-type impurity, and silicon (Si) is exemplified as an n-type impurity.
Of the n-type nitride semiconductor layer, the portion including the interface with the substrate preferably has substantially the same composition as the substrate or the buffer layer of the substrate. As a result, two-dimensional growth of the n-type nitride semiconductor layer is promoted, and undesirable island formation can be avoided. Further, by avoiding such island formation, it is possible to avoid an undesirable elastic strain relaxation in the n-type nitride semiconductor layer and the subsequent growth layer.

The light emitting layer includes, for example, a multiple quantum well (MQW) layer. The MQW layer includes a plurality of quantum wells, and each quantum well is made of, for example, InAlGaN or AlGaN. For example, the MQW layer includes an Al _x Ga _1-x N quantum well and an Al _y Ga _1-y N quantum well, one of which is stacked on the other. Here, the composition x of the Al _x Ga _1-x N quantum well is different from the composition y of the Al _y Ga _1-y N quantum well. The difference between the composition x and the composition y is preferably large enough to obtain good confinement of electrons and holes in the active region. This can increase the ratio of radioactive recombination to non-radioactive recombination.
The p-type nitride semiconductor layer is formed on the light emitting layer and is made of, for example, InAlGaN doped with impurities or AlGaN doped with impurities. Examples of the impurity include magnesium (Mg) as a p-type impurity and silicon (Si) as an n-type impurity.

The number of nitride semiconductor layers included in the ultraviolet light emitting element may be one or plural. From the viewpoint of improving the light emission amount per unit area, the ultraviolet light emitting element may preferably include a plurality of nitride semiconductor layers connected in parallel. Further, the shape of the nitride semiconductor layer is not particularly limited, and may be, for example, a rectangular shape, a circular shape, an elliptical shape, a polygonal shape, or a combination thereof in a plan view.
When an electrode is formed on the ultraviolet light emitting element, the electrode is made of a conductive material. The electrode can be made of, for example, gold (Au), nickel (Ni), aluminum (Al), titanium (Ti), or a combination thereof. For example, the electrode connected to the p-type nitride semiconductor layer can be made of a Ni / Au alloy. The electrode connected to the n-type nitride semiconductor layer can be composed of a Ti / Al / Ti / Au stack. These electrodes can be formed, for example, by sputtering or evaporation.

<Case>
In the ultraviolet light emitting device according to the embodiment of the present invention, the housing has a connection wiring on the surface or inside thereof, or on the surface and inside thereof. An electrical signal can be output to the outside through this connection wiring. The connection wiring is not particularly limited as long as it is a conductive material, but it has a lead structure in which copper, nickel or the like is subjected to surface treatment such as gold, nickel, palladium or silver, a paste mainly composed of silver or tungsten, Examples thereof include gold, copper, nickel, titanium, and cobalt films formed by plating, vapor deposition, and sputtering.

  It is preferable that the casing has a space (cavity structure) having a concave section in which the bonding substrate and the ultraviolet light emitting element can be accommodated. The bonding substrate may be bonded to the bottom of the recess of the housing using an adhesive. The adhesive may be either conductive or insulating, but in order to improve thermal conductivity, an adhesive having a high content of conductive material such as silver is particularly preferable. Examples of the material of the housing include a resin package, a ceramic package, and a metal material, but are not particularly limited thereto. In addition, a combination of a resin package and a metal member, a combination of a ceramic material and a metal material, or the like is also applicable.

<Wire>
In the ultraviolet light emitting device according to one embodiment of the present invention, the wire electrically connects the bonding substrate and the connection wiring. A wire generally used in the assembly process of semiconductors such as gold and copper can be used. Further, when the wire is sealed by a first resin layer and a second resin layer, which will be described later, for example, when the lower part of the wire is sealed by the first resin layer and the upper part is sealed by the second resin layer, the first resin Since different stress is applied to each part of the wire by the layer and the second resin layer, disconnection or the like is likely to occur. Therefore, it is more preferable that the wire is completely covered with the first resin layer.
The first resin layer and the second resin layer are filled in the recesses of the housing as a package in order to improve the mechanical strength. Therefore, the edge part of the edge side of the recessed part of the housing | casing in which an ultraviolet light emitting element is accommodated is the 2nd main surface of the board | substrate contained in an ultraviolet light emitting element, ie, a surface on the opposite side to the surface in which the nitride semiconductor layer was formed. It is desirable that it is above.

<First resin layer>
In the ultraviolet light emitting device according to an embodiment of the present invention, the first resin layer seals at least a part of the side surface of the bonding substrate, the ultraviolet light emitting element, and at least a part of the wire. The upper surface of the first resin layer may be flat or may have a non-flat surface shape. As an example of the first resin layer, an epoxy resin can be used, but is not particularly limited thereto. In particular, it is desirable that the first resin layer does not transmit ultraviolet rays, and the ultraviolet transmittance of the first resin layer is preferably 20% or less. Here, the ultraviolet ray means light having a wavelength of 260 nm or more and 320 nm or less. Further, the ultraviolet transmittance of 20% or less means that the transmittance of any one wavelength is 20% or less in the above-mentioned wavelength range.

Further, the ultraviolet transmittance of the first resin layer is more preferably 10% or less. This is because when the ultraviolet rays are transmitted through the first resin layer, the resin forming the first resin layer may be altered or contracted, and an external force such as stress may be applied to the wire to cause disconnection or the like.
Further, when the edge of the nitride semiconductor layer opposite to the substrate is taken as a reference and the direction perpendicular to the substrate is the height of the ultraviolet light emitting element, the interface between the first resin layer and the second resin layer described later is It is preferable to be in a position that is equal to or less than a position that is ½ the height of the ultraviolet light emitting element. If the first resin layer is higher than the position at which the height of the ultraviolet light emitting element is ½, the first resin layer easily goes around the second main surface of the substrate included in the ultraviolet light emitting element. Therefore, the position of the interface between the first resin layer and the second resin layer is preferably equal to or less than a position that is ½ of the height of the ultraviolet light emitting element. Thereby, at least the side surface of the end portion of the nitride semiconductor layer on the substrate side is covered with the second resin layer, and it is possible to further improve the extraction efficiency of light emitted from the side surface of the ultraviolet light emitting element. Become.

<Second resin layer>
In the ultraviolet light emitting device according to an embodiment of the present invention, the second resin layer seals the upper part of the first resin layer in the recess of the housing. Here, the “upper part of the first resin layer” means that the second resin layer is formed on at least a part of the upper part of the side surface of the first resin layer. From the viewpoint of further improving the extraction efficiency of ultraviolet rays radiated from the side surface of the ultraviolet light emitting element, the ultraviolet transmittance of the second resin layer is preferably 80% or more. Here, the ultraviolet ray means light having a wavelength of 260 nm or more and 320 nm or less. Further, the UV transmittance of 80% or more means that the transmittance of any one wavelength is 80% or more in the above-mentioned wavelength region. More preferably, the ultraviolet transmittance of the second resin layer is 90% or more. The thickness of the second resin layer is not particularly limited. The second resin layer is preferably used as the uppermost layer when it is gel after curing. That is, it is preferable to use so that no other layer is formed on the second resin layer.

<Lens>
The ultraviolet light emitting device according to an embodiment of the present invention may further include a lens on the second main surface of the substrate including the ultraviolet light emitting element. Examples of the lens forming material include quartz and sapphire. When a lens is manufactured using a sol-gel method, the lens forming material may be a resin material. The shape of the lens is not particularly limited, but any shape such as a hemispherical type, a shell type, and a flat plate type may be used. Further, a member having an optical refractive index control or a wavelength filter function may be further formed on the lens. It is also preferable to provide an adhesive layer between the lens and the substrate and bond them together. In this case, the ultraviolet transmittance of the adhesive layer is preferably 80% or more in a wavelength region of 260 nm or more and 320 nm or less. More preferably, the ultraviolet transmittance is preferably 90% or more. As a material used for the adhesive layer, a material resistant to ultraviolet rays is preferable. The adhesive layer can be formed of, for example, a resin whose main component is silicone. Among these, from the viewpoint of adhesion between the substrate and the lens, a thermosetting resin such as dimethyl silicone or silicone oil is desirable. The thickness of the adhesive layer is preferably 0.1 μm or more and 10 μm or less from the viewpoint of suppressing deterioration due to absorption of ultraviolet rays. The silicone resin preferably does not have a phenyl group that absorbs ultraviolet rays, and it is particularly desirable to use dimethyl silicone or silicone oil. Examples of applicable silicone resins include OE and JCR series manufactured by Dow Corning, Deep UV200 manufactured by Schott, and the like. Further, as a lens, a glass-based material can be used. Cytop (registered trademark) of Asahi Glass Co., Ltd., Novaxil of Crystal Material, etc. can also be used, but are not limited to the above materials. Absent.

<Device>
Moreover, you may produce the apparatus provided with the ultraviolet light emitting element which concerns on one Embodiment of this invention. The ultraviolet light emitting device according to one embodiment of the present invention can be used for various devices such as sterilization, measurement, resin curing, treatment, and semiconductor processing using ultraviolet rays emitted from the ultraviolet light emitting device.
Examples of the apparatus include a sterilization apparatus, a measurement apparatus, a resin curing apparatus, and the like.
As an example of the sterilizer, by incorporating an ultraviolet light-emitting device in various devices such as a refrigerator, an air cleaner, a humidifier, a dehumidifier, and a toilet, it is possible to sterilize a place where germs easily propagate.

Further, as another example of the sterilization apparatus, by incorporating the ultraviolet light emitting apparatus according to one embodiment of the present invention in a water server, a water purifier, a water supply device, a waste water treatment apparatus, a water sterilization module for dialysis, etc. The germs contained in the fluid can be sterilized.
As another example of the sterilizing apparatus, the ultraviolet light emitting device according to one embodiment of the present invention is incorporated in a vacuum cleaner, a futon dryer, a shoe dryer, a washing machine, a clothes dryer, or the like, thereby allowing a floor or cloth to be used. It is possible to sterilize miscellaneous bacteria contained on the surface and the like.
Moreover, as another example of the sterilization apparatus, bacteria in the air can be sterilized by incorporating the ultraviolet light emitting apparatus according to one embodiment of the present invention into an indoor sterilization lamp.

Next, an ultraviolet light emitting device according to an embodiment of the present invention will be described with reference to the drawings.
<First Embodiment>
FIG. 1 shows an example of a cross-sectional view of the ultraviolet light emitting device according to the first embodiment of the present invention.
The ultraviolet light emitting device 1 according to the first embodiment includes a bonding substrate 2, an ultraviolet light emitting element 3 having a substrate 3a and a nitride semiconductor layer 3b, a casing 4 having a connection wiring 4a, a bonding substrate 2 and a casing 4. Are provided with a wire 5, a first resin layer 6, and a second resin layer 7.
The bonding substrate 2 is provided at the bottom of the recess 4b of the housing 4 having a concave cross section. The ultraviolet light emitting element 3 includes a nitride semiconductor layer 3b disposed on the first main surface 31 of the substrate 3a, and the ultraviolet light emitting element 3 is arranged such that the nitride semiconductor layer 3b side of the ultraviolet light emitting element 3 faces the bonding substrate 2. Are electrically connected to the bonding substrate 2 via the solder 8.

Although FIG. 1 shows an example in which the bonding substrate 2 and the ultraviolet light emitting element 3 are electrically connected via the solder 8, the invention is not particularly limited to the solder 8.
The connection wiring 4 a is provided at the bottom portion of the recess 4 b of the housing 4, and the bonding substrate 2 and the connection wiring 4 a are electrically connected via the wire 5.
The housing 4 has a second main surface 32 opposite to the first main surface 31 of the substrate 3a of the ultraviolet light emitting element 3 accommodated in the housing 4 in a sectional view. It is formed so as to be approximately coincident with the portion. Then, the first resin layer 6 is filled in the concave portion 4b of the housing 4 so as to cover the bonding substrate 2, the connection wiring 4a, and the entire wire 5, and the second resin layer 7 is further formed on the first resin layer 6. Is filled. The first resin layer 6 is formed so that the upper surface thereof reaches a position about a half of the height of the ultraviolet light emitting element 3 disposed in the housing 4 in a sectional view, and the second resin layer 7 The upper surface is formed so as to substantially coincide with the opening side end of the housing 4. Therefore, a part of the side surface of the bonding substrate 2, the connection wiring 4a and the wire 5, and the nitride semiconductor layer 3b is covered with the first resin layer 6, and the other part of the side surface of the nitride semiconductor layer 3b and the substrate 3a. Are covered with the second resin layer 7.

By filling the first resin layer 6 and the second resin layer 7 in the recess 4b of the housing 4 in this way, the mechanical strength of the ultraviolet light emitting device can be improved.
Moreover, since the wire 5 whole is sealed only by the 1st resin layer 6, the wire 5 can be protected further. That is, since the wire 5 is covered only with the first resin layer 6, external force such as stress applied to the wire 5 is reduced by making the first resin layer 6 a material resistant to ultraviolet rays. And durability can be improved.
The second resin layer 7 has a high ultraviolet transmittance and seals the upper part of the first resin layer 6. Thereby, the refractive index difference between the nitride semiconductor layer 3b that emits light and the air can be relaxed by the second resin layer 7, and the extraction efficiency of the light emitted from the side surface of the ultraviolet light emitting element 3 can be improved. Can do.

Second Embodiment
FIG. 2 shows an example of a cross-sectional view of an ultraviolet light emitting device according to the second embodiment of the present invention.
The ultraviolet light emitting device 11 according to the second embodiment is further provided with a lens 12 in the ultraviolet light emitting device 1 according to the first embodiment shown in FIG. The same parts as those of the ultraviolet light emitting device 1 are denoted by the same reference numerals, and detailed description thereof is omitted.
As shown in FIG. 2, the ultraviolet light emitting device 11 is arranged so that the second main surface 32 of the substrate 3 a of the ultraviolet light emitting element 3 is positioned lower than the opening side end of the housing 4 in a cross-sectional view. The
Then, the hemispherical lens 12 having a diameter larger than the width of the substrate 3a in a cross-sectional view is disposed on the second main surface 32 of the substrate 3a.
By further including the lens 12 on the second main surface 32 of the substrate 3a, the light extraction efficiency can be further increased.

  Next, the ultraviolet light emitting device in one embodiment of the present invention will be described more specifically with reference to examples and comparative examples. In addition, this invention is not limited to each Example demonstrated below.

Example 1
A nitride semiconductor layer having an MQW layer p-GaN layer in which n-AlGaN layers, AlGaN and GaN are alternately stacked by MOCVD method on the first main surface side of an aluminum nitride single crystal substrate (3a) having a thickness of 200 μm 3b was formed. The nitride semiconductor layer 3b is etched to form a mesa shape, and an electrode in which Ni, Al, Ni, Ti, and Au are stacked in this order is formed on the n-AlGaN layer, and the p-GaN layer is formed. An electrode in which Ni, Ti and Au were laminated in this order was formed to obtain an ultraviolet light emitting device.
The obtained ultraviolet light-emitting element was flip-chip mounted on the bonding substrate 2 using aluminum nitride ceramic as a base material.

Next, the bonding substrate 2 was fixed to the bottom surface of the recess 4b of the housing 4 using silver paste. Furthermore, the connection board | substrate 4 and the connection wiring 4a provided in the housing | casing 4 were electrically connected with the gold wire (5).
Next, a silicone resin was applied to a thickness of 1 micron on the second main surface of the aluminum nitride single crystal substrate (3a), and a hemispherical lens 12 made of quartz was mounted thereon. Next, an epoxy resin (corresponding to the first resin layer 6) was filled in the recess 4b of the housing 4. The height of the epoxy resin (6) was controlled to be 120 μm from the upper surface of the ultraviolet light emitting element 3. Further, the loop apex of the gold wire (5) was not covered with the epoxy layer.
Finally, a silicone resin (corresponding to the second resin layer 7) used for the adhesive layer for the lens 12 was additionally filled. The silicone resin (7) was filled until reaching the bottom surface of the hemispherical lens, and the ultraviolet light emitting device 11 was obtained.

(Example 2)
An ultraviolet light emitting device was produced in the same manner as in Example 1 except that the epoxy resin (corresponding to the first resin layer 6) was filled until the gold wire 5 was completely covered.

(Comparative Example 1)
The region sealed with the epoxy resin (corresponding to the first resin layer 6) in Example 1 was also the same as that of Example 1 except that it was sealed with the silicone resin (corresponding to the second resin layer 7). An ultraviolet light emitting device was produced. That is, in Comparative Example 1, the epoxy resin was not sealed, and all the recesses 4b of the housing 4 were sealed with a silicone resin.

(Comparative Example 2)
In the same manner as in Comparative Example 1 except that the region sealed with the silicone resin (corresponding to the second resin layer 7) in Comparative Example 1 was sealed with an epoxy resin (corresponding to the first resin layer 6). A light emitting device was manufactured. That is, in Comparative Example 2, the silicone resin was not sealed, and all the recesses 4b of the housing 4 were sealed with an epoxy resin.

<Comparison experiment conducted>
Ten ultraviolet light emitting devices were produced by the methods shown in Examples 1 and 2 and Comparative Examples 1 and 2, respectively. An energization test was performed on the obtained ultraviolet light emitting device under the condition of 300 mA / 1000 Hr. As a criterion for the current test, the relative output value when the UV light emitting device that is electrically shorted or opened during disconnection is considered defective and the light output before power is normalized to “1” is used. Comparative evaluation was made. Table 1 summarizes the evaluation results. In Table 1, light output represents an average value of relative output values of 10 ultraviolet light emitting devices.

  As shown in Table 1, in the structure of Comparative Example 1, five electrical failures occurred. When the external appearance of the ultraviolet light emitting device determined to be an electrical failure mode was confirmed, it was confirmed that the gold wire (5) was broken at a position corresponding to the upper side of the bonding substrate 2. Similarly, in Comparative Example 1, it was confirmed that the silicone resin (corresponding to the second resin layer 7) that was in a gel state before the test was cured after the test and had many cracks. This is presumably because the silicone resin was denatured or cured by the ultraviolet rays radiated from the ultraviolet light emitting element 3, and the gold wire (5) was cut by the stress at the time of the crack occurrence.

Regarding Comparative Example 2, no electrical failure occurred, but the average output after the test was about 10% lower than Examples 1 and 2. This is presumably because part of the light emitted from the side surface of the ultraviolet light emitting element by the epoxy resin is not taken out.
It was confirmed that the ultraviolet light emitting devices of Example 1 and Example 2 were free from poor electrical characteristics and light output.

DESCRIPTION OF SYMBOLS 1, 11 Ultraviolet light-emitting device 2 Bonding board 3 Ultraviolet light-emitting element 3a Substrate 3b Nitride semiconductor layer 4 Case 4a Connection wiring 4b Recessed part 5 Wire 6 First resin layer 7 Second resin layer 8 Solder 12 Lens

Claims (9)

An ultraviolet light emitting device comprising a substrate having a nitride semiconductor layer on one side;
An upper surface is disposed to face the surface of the substrate having the nitride semiconductor layer, and is a bonded substrate that is electrically connected to the ultraviolet light emitting element.
A housing having connection wiring for external connection;
A wire for electrically connecting the bonding substrate and the connection wiring;
A first resin layer that seals at least a portion of the wire;
An ultraviolet light emitting device comprising: a second resin layer provided on an upper layer of the first resin layer and having different characteristics from the first resin layer.   The ultraviolet light emitting device according to claim 1, wherein the first resin layer has a lower ultraviolet transmittance than the second resin layer. The housing has a recess for accommodating the ultraviolet light emitting element and the bonding substrate,
The ultraviolet light emitting element and the bonding substrate are arranged such that the bonding substrate is on the bottom surface side of the recess,
The first resin layer is formed so as to cover the entire bonding substrate, a part of a side surface of the nitride semiconductor layer, and at least a part of the wire,
The ultraviolet light emitting device according to claim 1, wherein the second resin layer is formed so as to cover at least an end portion of the side surface of the nitride semiconductor layer on the substrate side.   The ultraviolet light-emitting device according to claim 1, wherein the entire wire is covered with the first resin layer. When the direction perpendicular to the substrate from the end of the ultraviolet light emitting element on the bonding substrate side is the height of the ultraviolet light emitting element,
5. The position of the interface between the first resin layer and the second resin layer is equal to or less than a position that is ½ of the height of the ultraviolet light emitting element. 6. UV light emitting device.   The ultraviolet light emitting device according to any one of claims 1 to 5, wherein the second resin layer has an ultraviolet transmittance of 90% or more.   The ultraviolet light-emitting device according to claim 1, wherein the ultraviolet transmittance of the first resin layer is 10% or less.   The ultraviolet light emitting device according to any one of claims 1 to 7, further comprising a lens on a surface of the substrate opposite to the nitride semiconductor layer.   An apparatus comprising the ultraviolet light emitting device according to any one of claims 1 to 8.

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