JP2022051304A - Ultraviolet light-emitting element - Google Patents

Abstract

To provide an ultraviolet light-emitting element excellent in both practical light output and service life.SOLUTION: An ultraviolet light-emitting element comprises: a substrate 10; and a semiconductor lamination part 20 formed on the substrate. The semiconductor lamination part has: a base 211 that has a first nitride semiconductor layer of a first conductivity type; and a mesa part 212 projected from a part of the base. The mesa part has: a first nitride semiconductor layer 21b of the first conductivity type connected with the first nitride semiconductor layer of the base; a nitride semiconductor light-emitting layer 22 formed on the first nitride semiconductor layer 21b; and a second nitride semiconductor layer 23 of a second conductivity type formed on the nitride semiconductor light-emitting layer. The ultraviolet light-emitting element has a silicon nitride layer 32 that covers a lateral face 212b and a top face 212a of the mesa part 212. A composition ratio of silicon to nitrogen of the silicon nitride layer 32 (an Si/N ratio) is equal to or more than 1.0.SELECTED DRAWING: Figure 1

Description

The present invention relates to an ultraviolet light emitting device.

Ultraviolet light emitting devices using nitride semiconductors are highly expected in fields such as high-efficiency white lighting, sterilization, medical treatment, and high-speed treatment of environmental pollutants.
In conventional semiconductor light emitting devices that emit blue or white light, light emitting diodes (LEDs) are sealed with an organic member such as silicone resin in order to prevent external impact, dirt, and moisture intrusion. There is. Further, it is generally known that peripheral members are joined or mounted using an organic member such as a resin in order to suppress deterioration of characteristics and improve reliability of the semiconductor light emitting device.

In addition to the resin sealing method, as a method of preventing external impact, dirt, and infiltration of moisture, an insulating film such as silicon oxide or silicon nitride is formed on the semiconductor laminated portion or the electrode of the mesa structure of the semiconductor element. However, a method for protecting a semiconductor element is also generally known (see Patent Document 12).

Patent Document 1 describes forming an insulating protective film using Si ₃ N ₄ or SiO ₂ .
Patent Document 2 describes that a silicon nitride (SiN _x ) film, a silicon oxide (SiO ₂ ) film, or an oxynitride (SiON) film is formed as an insulating protective film. Further, in the method for forming a silicon nitride (SiN _x ) film described in Patent Document 2, it is described that an N-rich SiN _x film may be formed in the vicinity of the interface.

Japanese Unexamined Patent Publication No. 11-150301 Japanese Unexamined Patent Publication No. 10-189562

In the case of an ultraviolet light emitting element, particularly an ultraviolet light emitting element that emits ultraviolet rays having a wavelength of 300 nm or less, if protection is performed by resin encapsulation, the resin is deteriorated by the ultraviolet rays, so that the characteristics are deteriorated and the life is shortened. Further, in order to secure a sufficient life, the light output must be made very small, and it is difficult to achieve both a practical light output and a life. Further, even when Si ₃ N ₄ is used as the insulating protective film, there is room for improvement in terms of achieving both practical light output and longevity.
An object of the present invention is to provide an ultraviolet light emitting device having excellent both practical light output and long life.

In order to achieve the above problems, the ultraviolet light emitting device of one aspect of the present invention requires the following configurations (1) and (2) as essential requirements.
(1) A substrate and a semiconductor laminated portion formed on the substrate are provided, and the semiconductor laminated portion includes a base having a first conductive type first nitride semiconductor layer and a mesa protruding from a part on the base. Has a part. The mesa portion includes a first conductive type first nitride semiconductor layer continuous with the first nitride semiconductor layer at the base, a nitride semiconductor light emitting layer formed on the first nitride semiconductor layer, and a nitride semiconductor. It has a second conductive type second nitride semiconductor layer formed on the light emitting layer.
(2) It has a silicon nitride layer that covers the side surface and the top surface of the mesa portion. The composition ratio (Si / N ratio) of silicon to nitrogen in this silicon nitride layer is 1.0 or more.

The ultraviolet light emitting device of the present invention can be expected to be an ultraviolet light emitting device having excellent both practical light output and long life.

It is sectional drawing which shows the ultraviolet light emitting element of an embodiment.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the embodiments shown below. In the embodiments shown below, technically preferable limitations are made for carrying out the present invention, but this limitation is not an essential requirement of the present invention.
[overall structure]
First, the overall configuration of the ultraviolet light emitting device 100 of this embodiment will be described with reference to FIG. 1. FIG. 1 shows a cross section perpendicular to the substrate surface of the ultraviolet light emitting element 100.
As shown in FIG. 1, the ultraviolet light emitting element 100 includes a substrate 10, a semiconductor laminated portion 20 formed on the substrate 10, a protective film 30, a first electrode 40, a second electrode 50, and a pad electrode 60. To prepare for.

The semiconductor laminated portion 20 has a base portion 211 which is a first conductive type first nitride semiconductor layer 21a, and a mesa portion 212 protruding from a part on the base portion 211. The mesa portion 212 is a first conductive type first nitride semiconductor layer 21b continuous with the first nitride semiconductor layer 21a of the base 211, and a nitride semiconductor formed on a part of the first nitride semiconductor layer 21b. It has a light emitting layer 22 and a second conductive type second nitride semiconductor layer 23 formed on the nitride semiconductor light emitting layer 22. The inclination angle α on the side surface of the mesa portion 212 is an acute angle.

The protective film 30 has a two-layer structure of a silicon oxide layer 31 and a silicon nitride layer 32, and has an entire side surface 212b of the mesa portion 212 and a part of the top surface (upper surface of the second nitride semiconductor layer 23) 212a (the first). The portion where the two electrodes 50 are not formed) and a part of the upper surface 211a of the first nitride semiconductor layer 21a which is the base portion 211 (the portion where the first electrode 40 is not formed) are covered. The composition ratio (Si / N ratio) of silicon to nitrogen in the silicon nitride layer 32 is 1.0 or more.
The first electrode 40 is formed on a part of the first nitride semiconductor layer 21a, which is the base portion 211 of the semiconductor laminated portion 20.

The second electrode 50 is formed on a part of the second nitride semiconductor layer 23 constituting the mesa portion 212 of the semiconductor laminated portion 20.
The silicon oxide layer 31 of the protective film 30 directly covers the entire side surface 212b of the mesa portion 212, a part of the top surface 212a, and a part of the upper surface 211a of the first nitride semiconductor layer 21a which is the base portion 211. The silicon oxide layer 31 is formed with a gap between the first electrode 40 and the second electrode 50. The silicon nitride layer 32 covers the outside of the silicon oxide layer 31, and is also formed in the gap between the silicon oxide layer 31 and the first electrode 40 and the second electrode 50, and also on the upper peripheral edges of the first electrode 40 and the second electrode 50. Has been done.
The Pad electrode 60 is electrically connected to the first electrode 40 and the second electrode 50.

[Action, effect]
Generally, silicon nitride is expressed as Si ₃ N ₄ , and the composition ratio (Si / N ratio) of silicon to the chemically quantitative nitrogen of silicon nitride is 0.75. In the ultraviolet light emitting device 100 of the present embodiment, the protective film 30 including the silicon nitride layer 32 having a silicon composition ratio (Si / N ratio) of 1.0 or more with respect to nitrogen is used to cover the side surfaces 212b and the top surface 212a of the mesa portion 212. By coating, it is excellent in both practical light output and long life.
Further, since the inclination angle α of the side surface of the mesa portion 212 is an acute angle, the covering performance by the protective film 30 is superior as compared with the case where α is a right angle and an obtuse angle.

[Details about each layer]
<Board>
The substrate 10 is not particularly limited as long as it can form a first conductive type first nitride semiconductor layer on the substrate 10. Specific examples of the substrate 10 include sapphire, Si, SiC, MgO, Ga ₂ O ₃ , ZnO, GaN, InN, AlN, and a mixed crystal substrate thereof.
The viewpoint that the lattice constant difference from the n-type nitride semiconductor layer formed on the upper layer side of the substrate 10 is small, the penetration shift can be reduced by growing in a lattice matching system, and the lattice strain due to the generation of whole gas can be increased. Therefore, a single crystal substrate in which a nitride semiconductor such as GaN, AlN, or AlGaN is used as a bulk, or a nitride semiconductor layer (also referred to as a template) such as GaN, AlN, or AlGaN grown on a certain material is used as the substrate 10. It is preferable to use it. The substrate 10 may contain impurities.
Further, the substrate 10 may have a surface on the side opposite to the surface on which the semiconductor laminated portion 20 is formed processed, from the viewpoint of improving light extraction.

<Semiconductor laminated part>
As shown in FIG. 1, the semiconductor laminated portion 20 is a first conductive type first nitride semiconductor layer 21 (a first nitride semiconductor layer 21a forming a base 211 and a mesa continuous thereto) formed on the substrate 10. The first nitride semiconductor layer 21b) of the portion 212), the nitride semiconductor light emitting layer 22 formed on a part of the first nitride semiconductor layer 21 (on the first nitride semiconductor layer 21b of the mesa portion 212), and the like. It has a second conductive type second nitride semiconductor layer 23 formed on the nitride semiconductor light emitting layer 22.

In addition to the above layer, the ultraviolet light emitting element 100 of the present embodiment may further include a layer for exhibiting other functions such as a buffer layer, a barrier layer, and a contact layer.
In the ultraviolet light emitting device of the present embodiment, the "first conductive type" and "second conductive type" mean that when one is an n-type conductive type, the other is a p-type conductive type. That is, when the first conductive type nitride semiconductor layer is n-type, the second conductive type nitride semiconductor layer is p-type. From the viewpoint of productivity and luminous efficiency, it is preferable that the first conductive type nitride semiconductor layer is n-type.

The method for forming a semiconductor laminated portion having a mesa structure (a semiconductor laminated portion having a base portion having a first nitride semiconductor layer and a semiconductor laminated portion having a mesa portion protruding from a part on the base portion) is not particularly limited, but MBE is not particularly limited. It is possible to form by laminating each layer using a known film forming apparatus such as MOCVD or MOCVD, forming a mask pattern by a photolithography method, and etching a desired region by dry etching or wet etching.

<First conductive type first nitride semiconductor layer>
The first conductive type first nitride semiconductor layer 21 may be provided directly on the substrate 10 as shown in FIG. Further, a layer other than the first-type conductive type first nitride semiconductor layer 21 may be provided on the substrate 10, and the first-type conductive type first nitride semiconductor layer 21 may be provided on the layer. For example, a buffer layer is provided on the substrate 10, an n-type AlGaN layer is provided as a first-type conductive type first nitride semiconductor layer 21 on the buffer layer, and a nitride semiconductor light emitting layer 22 is provided on the n-type AlGaN layer. It may be provided.
The first type conductive type first nitride semiconductor layer 21 is not particularly limited as long as it is a nitride semiconductor, but it is desirable that it is a mixed crystal of AlN, GaN, and InN from the viewpoint of realizing high luminous efficiency. The first-type conductive type first nitride semiconductor layer 21 may contain group V elements such as P, As, and Sb, and impurities such as C, H, F, O, Mg, and Si.

<Light emitting layer>
As shown in FIG. 1, the nitride semiconductor light emitting layer 22 may be provided directly on the first nitride semiconductor layer 21b of the mesa portion. Further, a layer other than the nitride semiconductor light emitting layer 22 may be provided on the first nitride semiconductor layer 21b, and the nitride semiconductor light emitting layer 22 may be provided on the layer. The formation position of the nitride semiconductor light emitting layer 22 is not particularly limited. Specifically, the undoped AlGaN layer may be provided on the first nitride semiconductor layer 21b, and the nitride semiconductor light emitting layer 22 may be provided on the undoped AlGaN layer.

The nitride semiconductor light emitting layer 22 is not particularly limited as long as it is a nitride semiconductor layer, but it is desirable that the nitride semiconductor light emitting layer 22 is a mixed crystal of AlN, GaN, and InN from the viewpoint of achieving high luminous efficiency. In addition to N, the nitride semiconductor light emitting layer 22 may contain other Group V elements such as P, As, and Sb, and impurities such as C, H, F, O, Mg, and Si. The nitride semiconductor light emitting layer 22 may have a quantum well structure or a single layer structure, but it is desirable that the nitride semiconductor light emitting layer 22 has at least one well structure from the viewpoint of achieving high luminous efficiency.
Further, from the viewpoint of lattice matching of the nitride semiconductor layer formed on the substrate 10, it is desirable that the wavelength range of the ultraviolet rays emitted from the nitride semiconductor light emitting layer 22 is 210 nm or more and 300 nm or less.

<Second conductive type second nitride semiconductor layer>
The second conductive type second nitride semiconductor layer 23 may be provided directly on the nitride semiconductor light emitting layer 22 as shown in FIG. Further, even if a layer other than the second conductive type second nitride semiconductor layer 23 is provided on the nitride semiconductor light emitting layer 22, and the second conductive type second nitride semiconductor layer 23 is provided on the layer, the second conductive type second nitride semiconductor layer 23 is provided. good. For example, a gradient composition layer in which the ratio of constituent elements changes continuously or discretely is provided on the nitride semiconductor light emitting layer 22, and a second conductive type second nitride semiconductor layer 23 is provided on the inclined composition layer. May be good.
The formation position of the second conductive type second nitride semiconductor layer 23 is not particularly limited. The ultraviolet light emitting device 100 may further have a barrier layer having a relatively large band gap between the nitride semiconductor light emitting layer 22 and the inclined composition layer. In another form, the second conductive type second nitride semiconductor layer 23 may be directly or indirectly provided on the substrate 10.

<Protective film>
In the ultraviolet light emitting device 100 of the present embodiment, the protective film 30 has a double structure of a silicon oxide layer 31 and a silicon nitride layer 32 which is a SiN _x (X ≦ 1) layer, and is nitrided on the outside of the silicon oxide layer 31. The silicon layer 32 is formed.
The silicon oxide layer 31 may not be formed, or the silicon nitride layer 32 may be formed inside the silicon oxide layer 31. In that case, the silicon nitride layer 32 directly covers the entire side surface 212b of the mesa portion 212, a part of the top surface 212a, and a part of the upper surface 211a of the first nitride semiconductor layer 21a which is the base portion 211. Become.
Examples of the layer other than the silicon nitride layer 32 constituting the protective film 30 having a double structure include silicon oxide and aluminum oxide.

The method for forming the protective film is not particularly limited, but it can be formed by, for example, a plasma CVD device, a sputtering device, a vacuum vapor deposition device, or the like. When the silicon nitride layer is produced by a plasma CVD apparatus, a method of using monosilane (SiH ₄ ) as a supply gas of silicon as a constituent element and ammonia (NH ₃ ) as a supply gas of nitrogen is widely known.
The method of setting the composition ratio (Si / N ratio) of silicon to nitrogen in the silicon nitride layer to 1.0 or more is not particularly limited, but for example, when the plasma CVD method is used, the supply amount and supply ratio of the supply gas are adjusted. It is feasible.
From the viewpoint of productivity and stress on the device, the film thickness of the silicon nitride layer is preferably 10 nm or more and 1000 nm or less, and more preferably 50 nm or more and 500 nm or less.

<1st electrode, 2nd electrode>
In the ultraviolet light emitting element 100 of the present embodiment, the first electrode 40 and the second electrode 50 for supplying electric power to the nitride semiconductor light emitting layer 22 are formed on the upper surface 211a of the base 211 and the top surface 212a of the mesa portion 212, respectively. Has been done. The first electrode 40 may be formed on the back surface of the substrate 10 (the surface opposite to the surface on which the first nitride semiconductor layer is formed).

Each electrode is used, for example, for a Ni / Au alloy layer (typically used for p-type contacts) or a Ti / Al / Ti / Au stack layer (typically used for n-type contacts). ), For example, formed by sputtering or vapor deposition. The electrode may also include a UV (ultraviolet) reflector. The UV reflector reorients the photons that emit light toward the electrodes (so that the photons cannot escape from the semiconductor layer structure) and reorients the photons toward the desired light emitting surface, eg, the bottom surface. Thereby, it is designed to improve the extraction efficiency of photons generated in the active region of the device.
Further, the material of the electrode may be a conductive material such as gold, nickel, aluminum, titanium or a combination thereof.

[Applicable devices]
The ultraviolet light emitting element 100 according to the embodiment of the present invention can be applied to various devices.
The ultraviolet light emitting element 100 according to the embodiment of the present invention can be applied to all existing devices in which an ultraviolet lamp is used, and can be replaced. In particular, it is applicable to an apparatus using deep ultraviolet rays having a wavelength of 280 nm or less.

The ultraviolet light emitting element 100 according to one embodiment of the present invention can be applied to devices in, for example, medical or life science fields, environmental fields, industries or industrial fields, living or home appliances fields, agriculture fields, and other fields.
The ultraviolet light emitting device 100 according to an embodiment of the present invention includes a device for synthesizing or decomposing chemicals and chemical substances, a device for sterilizing liquids, gases, and solids (containers, foods, medical devices, etc.), a device for cleaning semiconductors, and a film. , Glass and metal surface modifiers, semiconductors, flat panel displays (FPDs), printed substrates (PCBs) and other exposure equipment for the manufacture of electronic products, printing or coating equipment, bonding or sealing equipment, films, patterns and mock It can be applied to transfer or molding equipment such as ups, and measurement or inspection equipment for banknotes, scratches, blood and chemical substances.

Examples of liquid sterilizers include automatic ice maker and ice trays in refrigerators, water tanks for ice storage containers and ice makers, freezers, ice makers, humidifiers, dehumidifiers, cold water tanks or hot water tanks for water servers, and the like. Channel piping, stationary water purifier, portable water purifier, water dispenser, water heater, wastewater treatment device, disposer, toilet drain trap, washing machine, dialysis water sterilization module, peritoneal dialysis connector sterilizer, disaster water storage system Etc., but this is not the case.

Examples of gas sterilizers include air purifiers, air conditioners, ceiling fans, floor and bedding vacuum cleaners, futon dryers, shoe dryers, washing machines, clothes dryers, indoor sterilizers, and storage ventilation. Systems, shoe boxes, tons, etc. can be mentioned, but this is not the case.
Examples of solid sterilizers (including surface sterilizers) include vacuum packers, conveyor belts, medical, dental, barber and beauty salon hand tool sterilizers, toothbrushes, toothbrush holders, chopstick boxes, cosmetic pouches, etc. Examples include, but are not limited to, drainage ditch lids, toilet bowl local cleaners, toilet bowl lids, and the like.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The present invention is not limited to the examples shown below.
<Example 1>
This sample is an ultraviolet light emitting device 100 having the structure described in the embodiment, and has the following configuration.
The substrate 10 is an AlN substrate. The first nitride semiconductor layer 21 is an n-Al _0.7 Ga _0.3 N layer containing 2.0 × 10 ²⁰ cm ^-3 of Si as an impurity, the film thickness of the base 211 is 400 nm, and the overall film thickness is 500 nm. Is.

The nitride semiconductor light emitting layer 22 alternately has five layers of Al _0.51 Ga _0.49 N (well layer) having a thickness of 2.0 nm and Si-doped Al _0.78 Ga _0.22 N (barrier layer) having a thickness of 8.0 nm. It is a multiple quantum well structure. The second nitride semiconductor layer 23 is a p-type GaN layer containing 2.0 × 10 ²⁰ cm ^-3 as an impurity, and has a film thickness of 10 nm.
The film thickness of the silicon oxide layer 31 of the protective film 30 is 240 nm. The film thickness of the silicon nitride layer 32 is 240 nm, and the composition ratio (Si / N ratio) of silicon to nitrogen in the silicon nitride layer 32 is 3.76.
The first electrode 40 is a Ti / Al / Ni / Au layer. The second electrode 50 is an alloy layer of Ni and Au. The Pad electrode 60 has a laminated structure of Ti and Au.

The ultraviolet light emitting element 100 was manufactured by the following method.
First, on an AlN substrate obtained from an AlN single crystal, an n-Al _0.7 Ga _0.3 N layer containing 2.0 × 10 ²⁰ cm ^-3 of Si as an impurity, the multiple quantum well structure of the above AlGaN, and Mg as an impurity. The p-GaN layer containing 2.0 × 10 ²⁰ cm ^-3 was formed in this order by the organic metal vapor phase growth method (MOCVD method). As a result, a laminate was formed on the AlN substrate.

Next, the laminated body on the AlN substrate is subjected to dry etching to remove a part of the in-plane to a predetermined depth, and the n—Al _0.7 Ga _0.3 N layer is partially exposed to form the base of the laminated body. The shape is such that the mesa portion 212 protrudes from the 211. This dry etching was performed using a chlorine-based gas after forming a resist pattern on the laminate by a photolithography method.
Next, using a plasma CVD apparatus, a 240 nm silicon oxide layer 31 is formed on the upper surface 211a of the base portion 211 of the semiconductor laminated portion 20 and the top surface 212a and the side surface 212b of the mesa portion 212, and a part thereof is wet-etched. It was removed to provide an opening to expose the first nitride semiconductor layer 21a of the base 211. The first electrode 40 was formed in this exposed portion so as to have a predetermined gap between the exposed portion and the inner surface of the opening.

Similarly, a part of the silicon oxide film was removed by a wet etching treatment to provide an opening, and the second nitride semiconductor layer 23 of the mesa portion 212 was exposed. The second electrode 50 was formed in this exposed portion so as to have a predetermined gap between the exposed portion and the inner surface of the opening.
Next, a silicon nitride layer 32 having a thickness of 240 nm was formed by a plasma CVD method so as to cover the entire surface (the entire upper surface and side surface) on the AlN substrate in this state. The film forming conditions were a film forming temperature: 280 ° C., a flow rate of the supply gas: monosilane 68 sccm, ammonia 21 sccm, a pressure: 90 Pa, a high frequency power: 150 W, and a film forming time: 311 seconds.

Next, using the resist pattern formed by the photolithography method, contact holes were formed at predetermined positions of the silicon nitride layer 32 (the upper part of the first electrode 40 and the upper part of the second electrode 50) by etching with CF ₄ .
Next, Ti was deposited at a thickness of 20 nm and Au at a thickness of 1000 nm in each of the formed contact holes in this order. As a result, the Pad electrode 60 was formed on the upper part of the first electrode 40 and the upper part of the second electrode 50. The steps up to this point were performed in the wafer state. Therefore, a wafer on which a large number of ultraviolet light emitting elements 100 were formed was obtained.

Next, this wafer was individualized by laser dicing, and the submount was flip-chip mounted by the GGI method to form a PKG.
With respect to the obtained ultraviolet light emitting element 100, the composition ratio (Si / N ratio) of silicon to nitrogen in the silicon nitride layer 32 was measured by energy dispersive X-ray fluorescence analysis (EDX analysis) (acceleration voltage: 3 kV). It was 3.76.
Further, when the emission intensity and the emission peak wavelength when a drive current of 500 mA was applied to the obtained ultraviolet light emitting element 100 in an environment of 25 ° C., the emission intensity was 74 mW and the emission peak wavelength was 267 nm. ..
Further, the obtained ultraviolet light emitting element 100 is subjected to a continuous energization test (25 ° C., drive current value 500 mA) as an index of life, and the time until the output reaches 70% of the initial value (also referred to as L70). Was evaluated and it was 3300 hours.

<Example 2>
Among the film forming conditions of the silicon nitride layer 32, the ultraviolet light emitting element 100 was obtained by the same method as in Example 1 except that the flow rate of the supply gas was 57 sccm for monosilane, 32 sccm for ammonia, and the film forming time was 350 seconds.
With respect to the obtained ultraviolet light emitting element 100, the composition ratio (Si / N ratio) of silicon to nitrogen in the silicon nitride layer 32 was measured by the same method as in Example 1 and found to be 1.04. Further, when the emission intensity and the emission peak wavelength of the obtained ultraviolet light emitting device 100 were examined by the same method as in Example 1, the emission intensity was 75 mW and the emission peak wavelength was 269 nm. Further, the obtained ultraviolet light emitting element 100 was subjected to a continuous energization test by the same method as in Example 1, and L70 was evaluated. It was 2600 hours.

<Comparative Example 1>
Among the film forming conditions of the silicon nitride layer 32, an ultraviolet light emitting element was obtained by the same method as in Example 1 except that the flow rate of the supply gas was 47 sccm for monosilane, 42 sccm for ammonia, and the film forming time was 401 seconds.
With respect to the obtained ultraviolet light emitting element, the composition ratio (Si / N ratio) of silicon to nitrogen in the silicon nitride layer 32 was measured by the same method as in Example 1 and found to be 0.75. Further, when the emission intensity and the emission peak wavelength of the obtained ultraviolet light emitting device were examined by the same method as in Example 1, the emission intensity was 75 mW and the emission peak wavelength was 269 nm. Further, the obtained ultraviolet light emitting device was subjected to a continuous energization test by the same method as in Example 1, and L70 was evaluated. It was 1400 hours.
These results are shown in Table 1 together with the configuration of each element.

The following can be seen from the results in Table 1.
The ultraviolet light emitting elements of Examples 1 and 2 having a Si / N ratio of the silicon nitride layer of 1.0 or more are the same as the ultraviolet light emitting elements of Comparative Example 1 having a Si / N ratio of less than 1.0 (0.75). In comparison, the initial value of the emission intensity was almost the same, but the value of L70 was large, the attenuation of the emission intensity was suppressed, and the life was extended.
It was also found that a silicon nitride layer having a large Si / N ratio can be produced by increasing the supply ratio of monosilane to ammonia.

10 Substrate 20 Semiconductor laminated part 211 Base part 212 Mesa part 212b Side surface of mesa part 212a Top surface of mesa part 21 First nitride semiconductor layer 21a First nitride semiconductor layer at base 21b First nitride semiconductor layer at mesa part 22 Nitride Material Semiconductor light emitting layer 23 Second nitride semiconductor layer 30 Protective film 31 Silicon oxide layer 32 Silicon nitride layer 40 First electrode 50 Second electrode 60 Pad electrode 100 Ultraviolet light emitting element

Claims (3)

A substrate and a semiconductor laminated portion formed on the substrate are provided.
The semiconductor laminated portion has a base portion having a first conductive type first nitride semiconductor layer and a mesa portion protruding from a part on the base portion.
The mesa portion includes a first conductive type first nitride semiconductor layer continuous with the first nitride semiconductor layer at the base portion, and a nitride semiconductor light emitting layer formed on the first nitride semiconductor layer. It has a second conductive type second nitride semiconductor layer formed on the nitride semiconductor light emitting layer, and has.
It has a silicon nitride layer that covers the side surface and the top surface of the mesa portion, and has a silicon nitride layer.
An ultraviolet light emitting element having a silicon composition ratio (Si / N ratio) of 1.0 or more to nitrogen in the silicon nitride layer. The ultraviolet light emitting device according to claim 1, wherein the silicon nitride layer has a film thickness of 50 nm or more and 500 nm or less. The ultraviolet light emitting device according to claim 1 or 2, which emits ultraviolet rays including light having a wavelength of 210 nm or more and 300 nm or less.

Images