JP5634003B2 - Light emitting device - Google Patents

Description

The present invention relates to a light emitting device having a light emitting element having a reflective structure.

  By combining the light source light emitted from the light emitting element and the wavelength conversion member that can be excited by this and emit light of a different hue from the light source light, light of various colors can be emitted based on the principle of light color mixing Light emitting devices have been developed. In particular, in recent years, it has attracted attention as a next-generation illumination with lower power consumption and longer life, and there is a demand for a high-quality light-emitting device with further improved light-emitting output and excellent weather resistance.

  In the above light emitting device, as an example of an improvement method related to output, when primary light from a light source or secondary light after wavelength conversion proceeds to a member constituting the light emitting device, a part of the light is absorbed. Measures are taken to prevent the loss of light. As one proposal, a light-emitting device has been developed in which the surface of an electrode of a light-emitting element is coated with an Ag layer having a high reflectance (Patent Document 1). For example, when the light emitting element 100 shown in FIG. 13 is mounted on a wiring board or the like, a face-down type whose main light emitting surface is the substrate 101 side (upper side) opposite to the electrode formation surface side (lower side in FIG. 13). These elements are shown upside down to show this. That is, the light emitting element 100 is formed by sequentially stacking an n-type semiconductor layer 102, an active layer 103, and a p-type semiconductor layer 104 on a substrate 101, and an n-side electrode 106 is formed in an exposed region of the n-type semiconductor layer 102. A p-side electrode 105 is provided on the p-type semiconductor layer 104. Further, the p-type electrode 105 is composed of a first metal layer 105a made of an Ag layer exhibiting a high reflectivity and a second metal layer 105b covering the surface.

  With this structure, when the primary light and the secondary light from the light source in the light emitting device advance toward the electrode 105 side, the light is reflected by the Ag layer exhibiting high reflectivity, and the substrate 100 which is the main light emitting surface. Since light can be guided to the side, light absorption to the metal electrode can be suppressed and light extraction efficiency can be improved.

  However, Ag tends to cause corrosion and ion migration under high temperature, high humidity, and electric field. If migration occurs, the electrode layer is disturbed, and there arises a problem that the emission intensity is reduced and the life is shortened due to a short circuit. Therefore, in order to suppress this, for example, in the light emitting device 100 of FIG. 13, the first reflective layer, which is an Ag layer, is covered with the second metal layer 105b made of a metal element other than Ag such as V or Ti. ing. In addition, it is necessary to take some measures against migration, such as forming an electrode with an alloy layer containing Ag. For this reason, there is a problem that the number of manufacturing steps and the number of parts increase, leading to high costs.

  Furthermore, a reflective structure using a non-metallic reflective film that can be substituted for a metallic reflective film such as Ag has been proposed (Patent Document 2). That is, a light-transmitting insulating film having an opening / separation part through a light-transmitting electrode on the surface of the semiconductor layer of the light-emitting element, and a pad that conducts to the light-transmitting electrode through the opening / separation part An electrode is provided, and a dielectric multilayer reflection film is provided on the light-transmitting insulating film. Thereby, the external quantum efficiency is improved, and the light extraction efficiency of the emitted light from the light source is improved.

On the other hand, by providing the reflective layer with a dielectric multilayer film with a wide reflection-corresponding region, the light emitted from the light emitting element can be reflected even when it is incident on the reflective film at an angle, that is, only in the vertical direction. In addition, there has been proposed a reflection structure having a function of suitably reflecting even obliquely incident light (Patent Document 3).
JP-A-11-220171 JP 2005-197289 A JP-A-7-226535

  However, when the light-emitting element having the above-described reflection structure is employed as the light source of the light-emitting device, the output of the light emitted from the element alone is improved, but the element with the increased output is used for the light-emitting device having the wavelength conversion member. When applied as an excitation light source, the output of mixed color light as expected was not obtained.

The present invention has been made to solve the conventional problems. An object of the present invention is to provide a light emitting device having capable of emitting an emission wavelength having a desired color with high output, the light-emitting element can realize luminescence with excellent weather resistance.

In order to achieve the above object, a first light emitting device of the present invention includes a semiconductor structure having a light emitting layer, a light extraction surface provided on one main surface side of the semiconductor structure, and the other main structure of the semiconductor structure. provided on the surface side, convertible an electrode electrically connected to the semiconductor structure, a light emitting device having a, the periphery of the light emitting element is arranged so as to cover the wavelength of the light emitted from the light emitting element A wavelength conversion member, wherein a reflection structure is formed between the semiconductor structure and the electrode, and the reflection structure has a center wavelength corresponding to the wavelength of light from the light emitting layer. From the center wavelength of the first reflection layer corresponding to the wavelength of the light that is wavelength-converted by the wavelength conversion member , which is laminated between the first reflection layer and the electrode, configure even longer central wavelength and a second reflection layer that reflects The central wavelength of at least one of the first reflective layer and the second reflective layer is in the visible light range, and the central wavelengths of the first reflective layer and the second reflective layer have different hues and have a complementary color relationship. Ah is, the reflecting structure, characterized by a dielectric multilayer film der Rukoto as a laminate of a material layer composed of two or more.

In the second light emitting device of the present invention, the center wavelength of the first reflective layer 4a is shorter than the wavelength of light from the light emitting layer, and the center wavelength of the second reflective layer 4b is the wavelength of light from the light emitting layer. It has a longer wavelength.

In the third light emitting device of the present invention, the center wavelength of the reflected light of the first reflective layer 4a is 0.8 times or more and less than 1.0 times the wavelength of the light from the light emitting layer 8, The center wavelength of the reflected light of the two reflecting layer 4b is 1.15 times or more and 1.40 times or less with respect to the wavelength of the light from the light emitting layer 8.

The fourth light emitting device of the present invention is characterized in that the wavelength of the light emitted from the light emitting layer 8 is 360 nm to 650 nm.

In the fifth light emitting device of the present invention, the reflection structure 4 further includes a third reflection layer, and the center wavelengths of the reflected light of the third reflection layer are the first reflection layer 4a and the second reflection layer. It is characterized by being in a wavelength region between the central wavelength of 4b.

In the sixth light emitting device of the present invention, the reflecting structure 4 is a dielectric multilayer film in which two or more kinds of material films are laminated.

In the seventh light emitting device of the present invention, a plurality of reflecting structures 34 in which a plurality of reflecting structures 4 are arranged in a horizontal direction with a predetermined interval are stacked in a plurality of stages so as to be separated from each other in parallel. The reflective structure group 34 is characterized in that the upper reflective structure 4 is formed so as to cover at least a part of the opening in the separation region in the horizontal direction of the reflective structure 4 positioned in the lower stage.

In the seventh light-emitting device of the present invention, the reflective structure is formed on at least a side surface of the semiconductor structure with an insulating film interposed therebetween.

In the ninth light emitting device of the present invention, the main surface of the semiconductor structure 11 is covered with the translucent conductive layer 13, and the reflective structure 4 is formed on at least a part of the translucent conductive layer 13. The electrode 3 includes a metal electrode layer 23 in contact with the reflective structure 4 and the translucent conductive layer 13.

The tenth light emitting device of the present invention is characterized in that the wavelength conversion member 12 is disposed in contact with or close to the light extraction surface 18 of the light emitting element 10.

In the eleventh light-emitting device of the present invention, the light-emitting element is an LED having a light emission peak wavelength at 360 to 800 nm, and the wavelength conversion member 12 is LAG, BAM, BAM: Mn, YAG, CCA, SCA, SCESN. , SESN, CESN, CASBN, and CaAlSiN ₃ : containing at least one phosphor selected from the group consisting of Eu.

According to the light emitting device of the present invention, the light that has traveled to the electrode formed on the surface facing the light extraction surface can be reflected toward the light extraction surface by the reflection structure. As a result, light loss due to absorption at the electrode can be reduced, and external quantum efficiency can be increased.

Moreover, if it is the light-emitting device of this invention, especially the output light of the light-emitting device which has the wavelength conversion member which can convert the wavelength of the emitted light from a light emitting element can be improved. Because not only the output light from the active layer but also the secondary light, that is, the light whose wavelength is converted by the wavelength conversion member, can be reflected with high efficiency, the output of the component light constituting the mixed color can be increased, and consequently This is because the output of the emitted light as the entire apparatus can be improved. In addition, since each component light is reflected by the same reflection structure in the element, a light emitting device excellent in the condensing property and directivity of the primary light and the secondary light can be obtained. Furthermore, since the difference in hue between the reflected primary light and secondary light can be corrected by using a reflective structure having wavelength selectivity, color unevenness of the mixed colors between the light emitting devices can be reduced.

Embodiments of the present invention will be described below with reference to the drawings. However, embodiments described below, to give a concrete form to technical ideas of the present invention, intended to illustrate the light emission device, the present invention does not specify the light emission device in the following. Further, in this specification, in order to facilitate understanding of the scope of claims, numbers corresponding to the members shown in the embodiments are indicated in the “claims” and “means for solving problems” sections. It is appended to the members shown. However, the members shown in the claims are not limited to the members in the embodiments. In particular, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in the examples are not intended to limit the scope of the present invention only unless otherwise specified, but are merely illustrative examples. Only.

  Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. Furthermore, in the following description, the same name and symbol indicate the same or the same members, and detailed description thereof will be omitted as appropriate. Furthermore, each element constituting the present invention may be configured such that a plurality of elements are constituted by the same member and the plurality of elements are shared by one member, and conversely, the function of one member is constituted by a plurality of members. It can also be realized by sharing. Further, in this specification, the term “upper” as used on a layer or the like is not necessarily limited to the case where the upper surface is formed in contact with the upper surface, but includes the case where the upper surface is separated from the upper surface. It is used to include the case where there is an intervening layer between them.

(Embodiment 1)
A light-emitting device 1 according to Embodiment 1 of the present invention is shown in a sectional view of FIG. The light emitting element 10 mounted on the light emitting device 1 in this figure employs an LED chip that is an example of a nitride semiconductor element, and this LED chip is flip-chip mounted on a submount that is one of the wiring boards 9. ing. Flip chip mounting is a mounting method in which the growth substrate 5 side facing the electrode forming surface is the main light extraction surface, and is also referred to as face-down mounting. The light-emitting element 10 in FIG. 1 is displayed upside down to indicate that it is flip-chip mounting.

  Further, in the light emitting device 1 of FIG. 1, a wavelength conversion member 12 is disposed in the vicinity of the light emitting element 10 that is flip-chip mounted. With the wavelength conversion member 12, the light emitted from the active layer 8 is emitted. Convert wavelength. Thereby, it is possible to obtain a light emitting device capable of emitting desired light by additive color mixing of the light emitted from the active layer 8 and the light wavelength-converted by the wavelength conversion member.

  The light emitting element 10 includes a semiconductor structure 11 having a light emitting layer 8. In the light emitting device 10 of FIG. 1, a nitride semiconductor layer as the semiconductor structure 11 is laminated on one main surface of a growth substrate 5 having a pair of opposing main surfaces. Specifically, in the light emitting device 10 of FIG. 1, a nitride semiconductor layer 11 including a first nitride semiconductor layer 6, an active layer 8, and a second nitride semiconductor layer 7 in this order on the lower surface side of the growth substrate 5. Are stacked. The first nitride semiconductor layer 6 and the second nitride semiconductor layer 7 are each provided with a first electrode 3A and a second electrode 3B that are electrically connected. When power is supplied from the outside through the first electrode 3A and the second electrode 3B, the light emitting element 10 emits light from the active layer 8, and from the upper surface side of the growth substrate 5 in FIG. The light is extracted. That is, in the light emitting element 10 of FIG. 1, the other main surface side (upper side in FIG. 1) opposite to the mounting surface side (lower side in FIG. 1) of the electrodes 3A and 3B on the growth substrate 5 is the main light extraction surface 18. And

  Further, each set of electrodes 3 including the first electrode 3A and the second electrode 3B has a reflective structure 4. Examples of the reflective structure 4 include a dielectric multilayer film 4 having a multilayer structure. The dielectric multilayer film 4 in the example of FIG. 1 has a multilayer structure in which two or more kinds of material films having different refractive indexes are alternately stacked, and is provided at least at a part between the semiconductor structure 11 and the electrode 3. The light having a desired wavelength can be selectively reflected. FIG. 2 is an enlarged view of the vicinity of the second electrode 3B in the light emitting device of FIG. Although the detailed structure of the dielectric multilayer film 4 will be described later, in the example of FIG. 2, the dielectric multilayer film 4 composed of the first reflective layer 4a and the second reflective layer 4b is formed horizontally and spaced apart from each other. Has been. The first reflective layer 4a has a reflection region having the light from the light emitting layer 8 as a central wavelength, while the second reflective layer 4b has a wavelength different from the central wavelength of the light from the light emitting layer 8. Has a reflection region with a center wavelength. Furthermore, the central wavelength of at least one of the first reflective layer 4a and the second reflective layer 4b is in the visible light range. In addition to the first reflective layer 4a and the second reflective layer 4b, the dielectric multilayer film 4 may include a third reflective layer having a reflective characteristic different from the center wavelength of these reflective layers. The central wavelength of the third reflective layer is preferably in a wavelength range between the central wavelengths of the first reflective layer 4a and the second reflective layer 4b. This is because the generation of a trough in the transmittance due to the interference action of the dielectric multilayer film 4 can be suppressed, and a highly efficient reflection effect can be realized continuously in a predetermined wavelength range. Further, the order of stacking the reflective layers in the dielectric multilayer film 4 is not particularly limited. Below, detailed description of each member of the light-emitting device 1 is described.

(Light emitting element)
FIG. 3 is a schematic cross-sectional view showing the light emitting device 10 of FIG. 1 before flip-chip mounting, that is, the state in which the growth substrate 5 is the bottom layer and the semiconductor structure 11 is stacked thereon. In the actual manufacturing process of the light emitting device, the nitride semiconductor element having each layer laminated on the upper surface of the growth substrate 5 is mounted upside down as shown in FIG. 4 is a plan view of the light-emitting element 10 and is an explanatory diagram for explaining a manufacturing process in which a reflective structure is formed. FIGS. 5 and 6 are plan views of the light-emitting element in one manufacturing process. In addition, the same code | symbol is attached | subjected about the same component and the detailed description is abbreviate | omitted. Below, the manufacturing method of a semiconductor element is demonstrated using FIGS.

  In the nitride semiconductor element such as the LED shown in FIG. 3 as the light emitting element 10, the n-type semiconductor layer as the first nitride semiconductor layer 6 and the active layer 8 are formed on the sapphire substrate as the growth substrate 5. A nitride semiconductor layer 11 obtained by epitaxially growing a certain light emitting layer and a p-type semiconductor layer as the second nitride semiconductor layer 7 in this order, and a translucent conductive layer 13 formed on the nitride semiconductor layer 11 Have. Examples of the crystal growth method that can be used include metal-organic chemical vapor deposition (MOCVD), hydride vapor deposition (HVPE), hydride CVD, and MBE (molecular beam epitaxy).

  Subsequently, the light emitting layer 8 and a part of the p-type semiconductor layer 7 are selectively removed by etching to expose a part of the n-type semiconductor layer 6, and an n-type pad electrode which is the first electrode 3A is further removed. Forming. A p-type pad electrode, which is the second electrode 3B, is formed on the same surface side as the n-type electrode 3A and on the translucent conductive layer 13. Further, only predetermined surfaces of the n-type pad electrode 3A and the p-type pad electrode 3B are exposed, and other portions can be covered with an insulating protective film. Note that the n-type pad electrode may be formed in the exposed region of the n-type semiconductor layer 6 with the translucent conductive layer 13 interposed therebetween. Hereinafter, each component of the semiconductor light emitting device 1 will be specifically described.

(Growth substrate)
The growth substrate 5 is a substrate on which the semiconductor layer 11 can be epitaxially grown, and the size and thickness of the substrate are not particularly limited. As a substrate in a nitride semiconductor, an insulating substrate such as sapphire or spinel (MgAl ₂ O ₄ ) whose main surface is any of C-plane, R-plane, and A-plane, and silicon carbide (6H, 4H, 3C). ), Silicon, ZnS, ZnO, Si, GaAs, diamond, and nitride semiconductor substrates such as lithium niobate and neodymium gallium oxide, and nitride semiconductor substrates such as GaN and AlN. A substrate (for example, 0.01 ° to 3.0 ° on the sapphire C surface) can also be used. Further, the semiconductor substrate structure without the substrate removed after the growth substrate 5 is formed after the semiconductor layer 11 is formed, the semiconductor layer taken out thereof is bonded to a supporting substrate, for example, a conductive substrate, a flip chip mounted structure, or the like. A structure in which a light-sensitive member / translucent substrate is bonded to a semiconductor layer can also be used. Specifically, if there is a growth substrate on the main surface on the light extraction side of the semiconductor layer, or a bonded member / substrate, it is made translucent, and if it is an opaque substrate, light-shielding, light-absorbing growth substrate, it is removed. When a semiconductor layer is bonded to such a substrate, the structure is provided on the light reflecting side of the main surface of the semiconductor layer. In the case where charges are supplied to the semiconductor layer from the light transmitting substrate / member on the light extraction side, it is preferable to use a conductive one. In addition, an element having a structure in which a semiconductor layer is bonded and covered with a light-transmitting member such as glass or resin may be used. The removal of the growth substrate can be carried out by polishing or LLO (Laser Lift Off) while being held on the chip mounting portion of the apparatus or submount, for example. Moreover, even if it is a translucent dissimilar board | substrate, light extraction efficiency and an output can be improved by removing a board | substrate, and it is preferable.

(Semiconductor layer)
As the semiconductor layer 11, the nitride semiconductor described in Examples and below is a short wavelength region in the visible light region, a near ultraviolet region, or a shorter wavelength region, the point and a light conversion member (phosphor). Are suitably used in a light emitting device in combination. In addition, the semiconductor is not limited thereto, and may be an InGaAs-based or GaP-based semiconductor.

(Light emitting element structure)
The light emitting element structure using a semiconductor layer is preferably a structure having an active layer between a first conductivity type (n-type) and a second conductivity type (p-type) layer, which will be described later. Other light emitting structures such as a structure to be used may be used. Each conductive type layer may be provided with an insulating, semi-insulating, and reverse conductive type structure in part, or may be a structure in which they are additionally provided for the first and second conductive type layers. A circuit structure, for example, a protective element structure may be additionally provided, and the substrate may be a part of the conductivity type of the light emitting element.

  The electrode provided in the semiconductor layer preferably has a structure in which electrodes of the first conductivity type (n-type) and second conductivity type (p-type) layers are provided on one main surface side described in the examples and below. There is no limitation, and a structure in which electrodes are provided to face each main surface of the semiconductor layer, for example, a structure in which electrodes are provided on the removal side in the substrate removal structure may be employed.

(Nitride semiconductor layer)
As the nitride semiconductor, the general formula _{In x Al y Ga 1-xy} N (0 ≦ x, 0 ≦ y, x + y ≦ 1) A, B and P, may be mixed with As. Further, the n-type semiconductor layer 6 and the p-type semiconductor layer 7 are not particularly limited to a single layer or a multilayer. The nitride semiconductor layer 11 has a light emitting layer 8 as an active layer, and this active layer has a single (SQW) or multiple quantum well structure (MQW). Details of the nitride semiconductor layer 11 will be described below.

  An n-type nitride semiconductor layer such as a Si-doped GaN n-type contact layer and a GaN / InGaN n-type layer are formed on a growth substrate via a nitride semiconductor underlayer such as a buffer layer, for example, a low-temperature growth thin film GaN and a GaN layer. Type multilayer film layer, p-type nitride semiconductor layer, eg, Mg-doped InGaN / AlGaN p-type multilayer film layer and Mg-doped GaN p-type contact layer, and further active between the p-type and n-type layers A structure having a layer is used.

The light emitting layer 8 (active layer) of nitride semiconductor includes, for example, _a well layer made of Al _a In _b Ga _1-ab N (0 ≦ a ≦ 1, 0 ≦ b ≦ 1, a + b ≦ 1), Al having _{c In d Ga 1-cd N} (0 ≦ c ≦ 1,0 ≦ d ≦ 1, c + d ≦ 1) quantum well structure including a made of the barrier layer. The nitride semiconductor used for the active layer may be any of non-doped, n-type impurity doped, and p-type impurity doped. Preferably, the non-doped or n-type impurity doped nitride semiconductor is used to increase the output of the light emitting device. be able to. As the barrier layer, a nitride semiconductor having a band gap energy larger than that of the well layer is used. By including Al in the well layer, a wavelength shorter than the wavelength 365 nm which is the band gap energy of GaN can be obtained. The wavelength of light emitted from the active layer is approximately 360 to 650 nm, preferably 380 to 560 nm, depending on the purpose and application of the light-emitting element.

  The composition of the well layer is preferably InGaN, and the composition of the barrier layer at that time is preferably GaN or InGaN. The film thickness of the well layer is preferably 1 nm or more and 30 nm or less, more preferably 2 nm or more and 20 nm or less, and a single quantum well of one well layer, a multiple quantum well structure of a plurality of well layers through a barrier layer, and the like it can.

  Further, examples of the laminated structure of the nitride semiconductor layer 11 include a homostructure having a MIS junction, a PIN junction, and a PN junction, a heterostructure, and a double hetero configuration. In addition, each layer may have a superlattice structure, or a single quantum well structure or a multiple quantum well structure in which the light emitting layer 8 as an active layer is formed in a thin film in which a quantum effect is generated.

  Next, a mask having a predetermined shape is formed on the surface of the p-type semiconductor layer 7, and the p-type semiconductor layer 7 and the light emitting layer 8 which is an active layer are etched. As a result, as shown in FIG. 4A, the n-type contact layer 6a constituting the n-type semiconductor layer 6 at a predetermined position is exposed.

(Light reflection structure)
Specifically, with respect to the basic structure of the light emitting element of the present invention, one of two opposing main surfaces of the semiconductor layer is a light extraction side and the other is a light reflection side. On this light reflecting side, a light reflecting structure is provided, particularly in a region having a light emitting structure such as an active layer.

  The light reflecting structure is provided as a part of the electrode structure, an overlapping structure with the electrode structure, an in-plane separation structure with the electrode structure, etc., and preferably has a large light emitting area corresponding to the light emitting structure and has a charge injection efficiency. A superposition structure is adopted so as to increase the height. Specifically, a reflective structure is provided between the translucent conductive layer, which is an electrode on the semiconductor layer contact side, and an external connection (pad) electrode connected to the outside of the element. The reflection structure between the electrodes is a structure that conducts between the electrodes. Specifically, it is preferable to have a structure in which a conduction path and a reflection region described below are arranged separately in a plane, but the present invention is not limited to this, and a conductive reflection structure may be used. This in-plane separation reflective structure has a conductive structure in the separation region, and thus can be configured to be insulative. In the case where an electrode is provided on the light extraction side, a partial electrode, a light transmissive electrode, a light transmissive electrode, or a structure in which these are combined can be used.

  The reflective structure of the present invention has a reflective portion whose reflectance depends on the emission wavelength. Specifically, the following dielectric multilayer film, DBR, or the like is used. In addition to this wavelength-dependent reflective part, it additionally has a translucent film and a metal reflective film that are reflected by the difference in refractive index with the semiconductor layer and the translucent member (wavelength-dependent reflective part, electrode). In this case, these translucent members are disposed on the semiconductor layer side, and the light-shielding metal reflective film is disposed on the outside thereof. Further, the arrangement of the wavelength-dependent film and the light-transmitting film is not particularly limited. It is preferable that each function can be enhanced by separating the reflection function and the reflection depending on the wavelength and direction depending on the wavelength-dependent film formation.

  These reflection structures are not only provided with a single structure, but also have multiple structures such as a superposition structure in which a reflection structure provided with each film / member is repeated, and a plurality of films / members with a reflection structure. Or a multiplexed structure. Specifically, the former reflection structure is superimposed as shown in FIG. 10 to be described later, and the latter multiplexing of constituent films and members is a variety of wavelength-dependent films such as dielectrics having different center wavelengths. A structure in which a multilayer film is stacked. In addition, although the example which forms each film | membrane and member which comprises a reflecting structure integrally is shown below, not only this but each film | membrane and member can also be made into a mutually different shape and pattern.

  In the above, the reflective structure provided corresponding to the light emitting structure has been described. However, the present invention is not limited to this, and a non-light emitting region such as an n electrode region described later, a side surface of a semiconductor layer or a side surface of a light emitting structure, or a region of an element surface In addition, a reflective structure can be provided, for example, in a superposed manner corresponding to a protective film described later.

  Hereinafter, the translucent conductive layer (electrode), dielectric multilayer film, insulating film (translucent film), electrode, and protective film in the reflective structure will be described in order.

(Translucent conductive layer)
Further, a light transmissive conductive layer 13 is formed on the p-type semiconductor layer 7. As shown in FIG. 4B, a conductive layer is formed on almost the entire surface of the p-type semiconductor layer 7 and the exposed n-type semiconductor layer 6, thereby spreading the current uniformly over the entire p-type semiconductor layer 7. By providing light, a reflective structure can be provided thereon.

  Further, the covering region of the translucent conductive layer 13 can be limited not only to the semiconductor layers of both the n-type semiconductor layer 6 and the p-type semiconductor layer 7 but to only one of the semiconductor layers. In the example of FIG. 4B ′, the translucent conductive layer 13 is not formed on the n-type semiconductor layer 6 but only the p-type semiconductor layer 7 is covered.

The translucent conductive layer 13 includes various types such as a transparent electrode, but is preferably an oxide containing at least one element selected from the group consisting of Zn, In, and Sn. Specifically, it is desirable to form the light-transmitting conductive layer 13 containing an oxide of Zn, In, or Sn, such as ITO, ZnO, In ₂ O ₃ , or SnO ₂ , and preferably ITO is used. Alternatively, a metal such as Ni may be a thin metal film such as 30 mm, other metal oxides, nitrides, compounds thereof, a light transmission structure such as a metal film having a window opening, or a composite of the above. . As described above, the conductive layer is formed on almost the entire surface of the exposed p-type semiconductor layer 7, whereby the current can be spread uniformly over the entire p-type semiconductor layer 7.

  The thickness of the translucent conductive layer 13 is a thickness that takes into consideration the light absorption and electrical resistance / sheet resistance of the layer, that is, the light reflection structure and the current spread, for example, 1 μm or less, specifically 10 nm. To 500 nm. Further, it is preferable that the wavelength is approximately an integral multiple of λ / 4 with respect to the wavelength λ of the light emitted from the active layer 8 because the light extraction efficiency is increased.

(Dielectric multilayer film)
Specifically, the dielectric multilayer film 4 shown in FIGS. 2, 3, and 4C is formed on at least a part of the interface 19 between the nitride semiconductor layer 11 and the electrode 3, and preferably has a predetermined pattern. It is formed so as to cover substantially the entire semiconductor layer and translucent conductive layer. Further, the number of in-plane arrangements of the dielectric multilayer film 4 is not particularly limited, but when a plurality of multilayer films are formed, they are preferably separated from each other. In particular, as shown in FIG. 3, when a reflective structure is formed through the insulating film 16, the reflective structure is spaced at a predetermined interval so as to open at least a part on the interface 19 with the translucent conductive layer 13. However, it is preferable to arrange them horizontally. Thus, power can be supplied from the external electrode side to the nitride semiconductor layer 11 side without blocking the conduction path 32 (see the arrow in FIG. 2) of the power supplied from the electrode.

The dielectric multilayer film 4 according to the first embodiment has a multilayer structure in which two or more kinds of material films having different refractive indexes are alternately stacked. The dielectric multilayer film 4 can reflect a predetermined wavelength with high efficiency. This is a multilayer film in which the dielectric multilayer film 4 is formed by alternately laminating films having different refractive indexes with a thickness of ¼ wavelength. An example of the dielectric multilayer film 4 is a dielectric in which at least two selected from at least one oxide or nitride selected from the group consisting of Si, Ti, Zr, Nb, Ta, and Al are repeatedly stacked. A multilayer film is preferred. More preferably, it is made of a material composed of a non-metallic element or a laminated structure of oxides, for example, a (SiO ₂ / TiO ₂ ) _n (n is a natural number) laminated structure.

  The dielectric multilayer film 4 shown in FIG. 3 is formed by laminating a first reflective layer 4a having the central wavelength of light from the active layer 8 and a second reflective layer 4b having a central wavelength different from the central wavelength. With a structure. The second reflective layer 4b can have a longer center wavelength and a wider reflection band than the first reflective layer 4a. Specifically, the second reflection layer 4b is a reflection corresponding to a wavelength region of 1.15 times to 1.40 times, preferably 1.20 times to 1.35 times the wavelength of light from the light emitting layer 8. Has characteristics. In addition, it is preferable that at least one of the first reflective layer 4a and the second reflective layer 4b has a central wavelength in the visible light range, and both reflective layers have different hues.

  The second reflective layer 4b is preferably composed of a pair of layers having a constant center wavelength, more preferably a plurality of pairs. Further, as another form, a plurality of layers having the constant center wavelength are preferably formed, for example, two sets. For example, you may have the 2nd, 3rd reflective layer of the below-mentioned Example, or more, and it is set as 1 set or 2 sets suitably. Further, in order to cope with the above wavelength range, the thickness of each layer in the multilayer film, or within the above wavelength range, with a continuously changing film thickness satisfying a predetermined difference series or geometric series. A plurality of layer pairs whose center wavelengths are gradually shifted can be used to broaden the band.

  The reflective structure 4 in the example of FIG. 3 includes a first reflective layer 4a corresponding to a narrow wavelength range and a second reflective layer 4b corresponding to a wide wavelength range. Thereby, the dispersion of the wavelength in the secondary light can be covered with the broadband second reflection layer 4b due to the dispersion of the Stokes shift caused by the error of the energy conversion amount. That is, the output of component light can be increased by making each reflection structure correspond to the light emission characteristics of component light of mixed color light, and as a result, a high output mixed color can be obtained. Moreover, by selecting the reflection wavelength range, it is possible to obtain outgoing light with improved color rendering, and on the other hand, it also serves as a filter that reduces the enhancement of the output of secondary light having an undesired hue. be able to.

  In particular, in the case of a light emitting device in which a yellow fluorescent material is combined with a blue excitation light source that is visible light, a white LED can be configured with only a single fluorescent material, so that optical characteristics can be easily adjusted and high conversion efficiency can be achieved. Can be obtained. In addition, compared with color conversion from ultraviolet light, the Stokes shift is small and essential energy conversion can be improved. Furthermore, since the transmitted light of the blue LED can be used, the luminous efficiency is high. Therefore, by mounting each of the light emitting devices having the light source light and the fluorescence by the combination of the hues, the reflection structure corresponding to the hue, the light loss can be reduced and the output can be further increased.

  In addition, since the hue of the component light can be substantially unified by adopting a reflection structure corresponding to the wavelength of the component light of the mixed color light emitted from the light emitting device, variation in the emission color between the light emitting elements or the light emitting devices can be reduced. . Furthermore, in the dielectric multilayer film, the center wavelength of reflection is limited to the light source light and the emission wavelength of the wavelength conversion member after excitation, so that it can be made thinner compared to a grating with a wide range of wavelengths. Simplification of the process is realized. In addition, when the primary light as the light source is incident on the dielectric multilayer film at an angle, the inclined light that has shifted to the long wavelength side can also be reflected by the second reflective layer 4b, and the light extraction efficiency of the device Can be improved.

(Dielectric multilayer film formation pattern)
Any pattern can be used as the pattern for forming the dielectric multilayer film 4. These patterns are formed on the resist pattern by a method such as RlE (reactive ion etching), ion milling, or lift-off. A preferable opening shape is a stripe shape shown in FIG. 5, a dot shape shown in FIG. 6, or a block shape. In the example of FIG. 4C, the opening 35 of the dielectric multilayer film 4 is patterned in a dot shape. Further, as shown in FIG. 3, the dielectric multilayer film 4 includes at least an opening 35, thereby having an exposed region of the translucent conductive layer 13. As shown in FIG. 2, this region becomes a conduction path 32 as a structure in which ITO is partially exposed and makes contact with the pad electrode, so that the contact resistance is substantially reduced and the forward voltage is reduced. Can be reduced. The formation pattern of the dielectric multilayer film 4 is not limited to the above example. For example, the dot shape may be a circle, an ellipse, a rectangle, a polygon, or the like, and the vertical and horizontal widths of the block pattern may be changed as appropriate. The block shape may be triangular, circular, semicircular, or polygonal, the arrangement may be staggered, or the shape and arrangement of various forming portions / openings may be used. Moreover, it is not restricted to the example arrange | positioned uniformly to the whole, A magnitude | size and a density can be changed suitably for every area | region, or said pattern can be combined.

  In the plan view of FIG. 4C, the reflective structure is formed only on the p-type semiconductor layer 7, but can also be provided on the n-type semiconductor layer 6 as shown in FIG. If the reflection structure is formed on both the first and second electrodes 3A and 3B, the light that has traveled to both regions can be selectively reflected to efficiently reduce the loss of light having a predetermined wavelength. In the light emitting device of the first embodiment, since both electrodes are arranged on the same surface side, if a reflecting structure is formed on both electrodes, a reflecting structure region is provided on almost the entire main surface of the light emitting element. Thus, the light extraction efficiency can be increased.

  In the light emitting device 10 of FIG. 3, the optical characteristics of the dielectric multilayer film 4 formed on both electrodes 3, more preferably the reflective structure, are substantially the same. Thereby, when the dielectric multilayer film 4 is substantially the same for both electrodes, color unevenness due to the light source of the light-emitting device 1 can be reduced, and the manufacturing process can be simplified by forming both simultaneously. On the other hand, the dielectric multilayer films 4 attached to the electrodes 3A and 3B may have a difference in optical characteristics. For example, the film thickness of the reflective layer can be determined in consideration of the incident angle of light by the electrode part, the distance from the wavelength conversion member, and the like.

(Insulating film)
In the nitride semiconductor device 10 of FIG. 2, a translucent insulating film 16 is interposed between the translucent conductive layer 13 and the dielectric multilayer film 4 that are appropriately formed on the semiconductor structure 11. And preferably provided within the reflective structure. The light-transmitting insulating film 16 has a high light-transmitting property so that the light from the light-emitting element 10 is efficiently reflected and part of the light-transmitting insulating film 16 is transmitted through the multilayer film 4. Therefore, the insulating film 16 is preferably an oxide, more preferably an oxide of at least one element selected from the group consisting of Si and Al. Specifically, SiO ₂ , Al ₂ O ₃ or the like is used, and preferably SiO ₂ is used.

  The thickness of the insulating film 16 is not particularly limited, and can be formed to a thickness of about 10 nm to 2 μm. In particular, the thickness of the insulating film 16 when provided together with the metal electrode layer formed on the upper surface of the insulating film 16 is preferably 10 nm to 500 nm.

(electrode)
After the reflective structure including the dielectric multilayer film 4 is formed on the translucent conductive layer 13, as shown in FIGS. 3 and 4D, a metal electrode layer 23 is formed, and the translucent conductive layer is formed on the translucent conductive layer. Electrically connected. The metal electrode layer 23 is in contact with the translucent conductive layer 13 appropriately provided on the p-type semiconductor layer 7 and the n-type semiconductor layer 6 side, and the dielectric multilayer film 4 having a reflective structure, and the first electrode 3A and Each is formed on the second electrode 3B side.

  The metal electrode layer electrically connects the light emitting element and the external electrode and functions as a pad electrode. For example, a conductive member 24 such as an Au bump is disposed on the surface of the metal electrode layer, and the electrode of the light emitting element is electrically connected to the external electrode opposed thereto via the conductive member. Further, the metal electrode layer is partly and directly connected to the translucent conductive layer 13. An existing configuration can be appropriately employed for the pad electrode. For example, it is made of any metal of Au, Pt, Pd, Rh, Ni, W, Mo, Cr, Ti, an alloy thereof, or a combination thereof. As an example of the metal electrode layer, a laminated structure of W / Pt / Au, Rh / Pt / Au, W / Pt / Au / Ni, Pt / Au, or Ti / Rh can be employed from the lower surface.

  In the present embodiment, the metal electrode layer is formed in contact with at least a part of the translucent conductive layer 13. In addition, a part of the metal electrode layer according to another embodiment of the present invention may be nitrided by extending into a through hole provided in the translucent conductive layer 13 or outside the translucent conductive layer 13. You may provide as a contact part which contacts a physical-semiconductor layer directly. Thus, adhesion can be enhanced by the contact part of the metal electrode layer.

  The metal electrode layers formed on the p-type nitride semiconductor layer 7 side and the n-type nitride semiconductor layer 6 side preferably have the same type and thickness of the metal used, because they are formed simultaneously. Compared with the case of forming separately, the process of forming a metal electrode layer can be simplified. The electrode on the n-type nitride semiconductor layer side when provided separately is, for example, a W / Pt / Au electrode laminated in order from the n-type nitride semiconductor layer 6 side (the film thickness is, for example, 20 nm / 200 nm / 500 nm, respectively) In addition, a W / Pt / Au / Ni or Ti / Rh / Pt / Au electrode in which Ni is further laminated can be used.

(Protective film)
After the metal electrode layer 23 is formed, the insulating protective film 14 can be formed on almost the entire surface of the semiconductor light emitting device 10 except for the connection region with the external region. In the example of FIG. 4E, openings 21 and 22 are formed in the protective film 14 covering the n-type electrode 3A portion and the p-type electrode 3B portion, respectively. For the protective film 14, SiO ₂ , TiO ₂ , Al ₂ O ₃ , polyimide, or the like can be used. In addition, as shown in the embodiment, the insulating film 16 and the protective film 14 may be used together in the same member, that is, the process is simplified by forming the protective film 14 and the insulating film 16 as the same process and the same film. This is preferable.

  In the above example, the example in which the light emitting element in which the p electrode and the n electrode exist on the same surface is flip-chip mounted has been described. However, the present invention is a pair of electrodes that the light emitting element sandwiches the light emitting layer up and down. It can also be used for so-called vertical light-emitting elements. In the electrode of the vertical light emitting element, at least the electrode on the wiring board side on which the light emitting element is mounted is provided with a reflective layer, so that the light traveling to the reflective layer can be reflected to the opposite light extraction surface side. . In addition, a reflection structure can be formed on the electrode formed on the light extraction surface side to suppress light absorption to the electrode, thereby increasing the external quantum efficiency.

(Light emitting device)
The light-emitting element obtained by the above method is flip-chip mounted on a wiring board to obtain a light-emitting device. As an example, a method of manufacturing the light emitting device 1 shown in FIG. 1 will be described with reference to FIG. First, as shown in FIG. 7A, bumps 24 are formed on a wafer 25 to be a submount substrate 9 according to a pattern for flip-chip mounting the light emitting element 10. Next, as shown in FIG. 7B, the light emitting element 10 is flip-chip mounted through the bumps 24. In this example, two LED chips are mounted side by side in a region where one submount substrate 9 is formed. Further, screen printing is performed in FIG. In the screen printing, a metal mask is placed on the wafer 25, a resin constituting the coating layer 26 is applied, and is spread with a squeegee. After the resin 26 is cured, the metal mask is removed and dicing is performed as shown in FIG. Each of the cut out submount substrates 9 is fixed on a support 27 through a eutectic layer 28 by eutectic die bonding as shown in FIG. Here, Au—Sn was used as eutectic solder, and eutectic was performed at about 290 ° C. Thereafter, as shown in FIG. 7E, the electrode of the submount substrate 9 and the electrode 29 of the support 27 are wired by wire bonding 31. Further, as shown in FIG. 7G, a resin lens 36 is fixed with an adhesive or the like so as to cover the outer periphery of the LED chip, thereby obtaining a light emitting device.

  However, the arrangement method of the resin 26 covering the periphery of the light emitting element 10 is not particularly limited. For example, it is possible to form a package that forms an interface of the region where the resin 26 is disposed, and to fill the inside with the resin 26. Further, the light emitting element may not be provided with a form that is directly mounted on a predetermined mounting portion of the light emitting device, that is, a submount. Further, the submount substrate cut out individually, or a substrate to which a lens or the like is bonded and sealed can be used as a light emitting device.

(Wavelength conversion member)
Further, as shown in FIG. 1, a wavelength conversion member 12 such as a fluorescent material that emits fluorescence when excited by the light of the light emitting element 10 is mixed in the resin 26 as a sealing member. That is, a part of the light from the light source excites the phosphor as the wavelength conversion member, so that light having a wavelength different from the wavelength of the main light source is obtained, and as a result, a desired hue due to color mixing is obtained. Output light can be realized. As the wavelength conversion member 12, a phosphor can be preferably used. This is because the phosphor also has functions of light scattering and light reflection, so that it can serve as a light scattering member in addition to the wavelength conversion function, and can obtain a light diffusion effect. The phosphor can be mixed in the resin 26 at a substantially uniform ratio or can be mixed so as to be partially unevenly distributed. For example, when the light comes close to the light emitting element, more phosphor light reaches the reflecting structure, and a light emitting device with high light emission output and high efficiency can be obtained. Further, by separating the light emitting element 10 from the light emitting element 10 by a predetermined distance, it is difficult for heat generated in the light emitting element 10 to be transmitted to the fluorescent substance, and deterioration of the fluorescent substance can be suppressed. Further, two or more kinds of phosphors may be present in the light emitting layer composed of one layer on the surface of the light emitting device, or one or more kinds of phosphors may be present in the light emitting layer composed of two layers. Thereby, a light emitting device having a desired wavelength can be realized. In addition to the resin, a translucent member such as glass, an aggregate of phosphor particles, and a member of the crystal can also be used.

Typical phosphors 12 include cadmium zinc sulfide associated with copper and YAG phosphors and LAG phosphors associated with cerium. In particular, at the time of high luminance and long-term use _{(Re 1-x Sm x)} 3 (Al 1-y Ga y) 5 O 12: Ce (0 ≦ x <1,0 ≦ y ≦ 1, where, Re Is at least one element selected from the group consisting of Y, Gd, La, and Lu. The YAG, LAG, BAM, BAM: Mn, CCA, SCA, SCESN, SESN, CESN, CASBN and CaAlSiN _3: phosphor containing at least one selected from the group consisting of Eu can be used.

  As the wavelength conversion member 12 of the first embodiment, a YAG phosphor is used, and light emitted from the light source and light having a wavelength different from that of the emitted light, part of which is excited by the phosphor 12 By mixing colors, for example, white can be obtained. Further, as the phosphor, phosphor glass or phosphor-containing resin obtained by mixing phosphor in glass or resin may be used. Further, those that are resistant to heat generated from the light source and those that are weather resistant not affected by the use environment are more desirable.

In the light emitting device 1, two or more kinds of phosphors may be mixed as the phosphor. It is also possible to increase the reddish component using a nitride phosphor having yellow to red light emission, and to realize illumination with high average color rendering index Ra, light bulb color LED, and the like. Specifically, by adjusting the amount of phosphors having different chromaticity points on the CIE chromaticity diagram according to the light emission wavelength of the light emitting device, the phosphors are connected with each other on the chromaticity diagram. Any point can be made to emit light. In addition, a nitride phosphor, oxynitride phosphor, silicate phosphor, L ₂ SiO ₄ : Eu (L is an alkaline earth metal) that converts near-ultraviolet to visible light into a yellow to red region, particularly (Sr _x Mae _1-x ) ₂ SiO ₄ : Eu (Mae is an alkaline earth metal such as Ca or Ba). Examples of nitride phosphors and oxynitride (oxynitride) phosphors include Sr—Ca—Si—N: Eu, Ca—Si—N: Eu, Sr—Si—N: Eu, and Sr—Ca—Si. —O—N: Eu, Ca—Si—O—N: Eu, Sr—Si—O—N: Eu, and the like. As the alkaline earth silicon nitride phosphor, the general formula LSi ₂ O ₂ N ₂ : Eu , general formula _{L x Si y N (2 /} 3x + 4 / 3y): Eu or _{L x Si y O z N (} 2 / 3x + 4 / 3y-2 / 3z): Eu (L is, Sr, Ca, One of Sr and Ca).

  Specifically, the phosphor 12 according to the first embodiment is unevenly distributed near the semiconductor light emitting element 1 as shown in FIG. As a result, the effect of reflecting or scattering the light emitted from the semiconductor light emitting element 1 is enhanced, and the light emitted from the light emitting device can have a wide range of light emission angles, so that light diffused in all directions can be obtained. Furthermore, by uniformly covering the periphery of the light emitting element with the wavelength conversion member, the amount of wavelength conversion by the part of the light emitting device can be made almost constant, thereby reducing light unevenness for each light emitting device and reducing light loss. it can. Moreover, since the distance until the emitted light from the light emitting element travels to the wavelength conversion member can be made substantially constant, the wavelength conversion amount and the diffusion amount are stabilized. That is, the mixing ratio of the primary light and the secondary light can be made substantially constant, and outgoing light with reduced color unevenness and light unevenness can be obtained.

  The material of the resin 26 as the sealing member is not particularly limited as long as it is translucent, and it is preferable to use a silicone resin composition, a modified silicone resin composition, etc. An insulating resin composition having translucency such as a composition and an acrylic resin composition can be used. Moreover, sealing members excellent in weather resistance, such as hybrid resins containing at least one of these resins, can also be used. Furthermore, inorganic materials having excellent light resistance such as glass and silica gel can be used. Furthermore, a lens effect can be provided by making the light emitting surface side of the sealing member have a desired shape, and light emitted from the light emitting element chip can be focused. In Embodiment 1, a silicone resin is used as the sealing member.

(Additive components)
In addition to the wavelength converting member, the sealing member can be added with an appropriate member such as a viscosity extender, a pigment, or a fluorescent material depending on the intended use, thereby obtaining a light emitting device having good directivity characteristics. It is done. Similarly, various colorants can be added as a filter material having a filter effect of cutting unnecessary wavelengths from extraneous light and light emitting elements.

  Here, in the present specification, the diffusing agent means that, for example, a material having a center particle diameter of 1 nm or more and less than 5 μm is produced by favorably irregularly reflecting light from the light emitting element 10 and the fluorescent material and using a fluorescent material having a large particle size. Color unevenness that is easy to suppress can be suppressed, and the half-value width of the emission spectrum can be narrowed, so that a light-emitting device with high color purity can be obtained. On the other hand, a diffusing agent having a wavelength of 1 nm or more and less than 1 μm has a low interference effect on the light wavelength from the light-emitting element 10, but has a high transparency and can increase the resin viscosity without reducing the light intensity.

(Filler)
Further, a filler may be contained in the sealing member in addition to the fluorescent material. As a specific material, the same material as the diffusing agent can be used. However, the diffusing agent and the filler have different center particle sizes. In this specification, the center particle size of the filler is preferably 5 μm or more and 100 μm or less. When a filler having such a particle size is contained in the sealing member, the chromaticity variation of the light emitting device is improved by the light scattering action, and the thermal shock resistance of the sealing member can be enhanced.

  Further, the emission peak wavelength of the emitted light output from the light emitting layer of the light emitting element mounted on the light emitting device is not particularly limited. For example, the short wavelength region from near ultraviolet to visible light is around 240 nm to 500 nm, preferably from 380 nm to A semiconductor light-emitting element having an emission spectrum at 420 nm or 450 nm to 470 nm can be used. In Embodiment 1, the light-emitting element 10 obtained by the above manufacturing method was used.

(Embodiment 2)
A schematic cross-sectional view of the light-emitting element according to Embodiment 2 is shown in FIG. Note that the light-emitting device according to Embodiment 2 is different from the light-emitting device according to Embodiment 1 only in the reflection structure of the light-emitting element mounted, and the other structures are substantially the same. . Therefore, in the light emitting element 20 according to Embodiment 2, the same components as those of the light emitting element 10 according to Embodiment 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The light emitting element 20 shown in FIG. 8 has a reflective structure group 34 in which a plurality of reflective structures 4 similar to those in the first embodiment are stacked. The dielectric multilayer films 4 are spaced apart from each other in parallel, and the plurality of dielectric multilayer films 4 arranged in a plane are referred to as a first-stage reflection structure group 34A for convenience.

  In addition to the first-stage reflection structure group 34A, a second-stage reflection structure group 34B is formed on the stacking direction side (upward). The first-stage reflective structure group 34A and the second-stage reflective structure group 34B cover at least a part of the opening region of the first-stage reflective structure group 34A in plan view from the stacking direction. Are arranged as follows. Thereby, in the planar view from the surface side of the electrode 3, since the formation area of a reflection structure increases, light extraction efficiency can be improved.

  Specifically, as shown in FIG. 8, a second-stage reflection structure group 34B is laminated on the upper surface of the first-stage reflection structure group 34A via a light-transmitting conductive layer 13 such as ITO. . Further, the first-stage reflecting structure group 34A and the second-stage reflecting structure group 34B are separated from each other without being in contact with each other, and thereby, from the side of the metal electrode layer 23 formed on the upper side of the reflecting structure group 34. A conduction path 32 (see FIG. 2) to the active layer 8 is provided to supply power to the semiconductor structure 11.

  In the example of FIG. 8, the dielectric multilayer film group is laminated in two stages, but the number of layers is not limited to two, but can be three or more, and the opening of the lower dielectric multilayer film group can be similarly formed in two stages. An upper dielectric multilayer film group is formed above the region via a light-transmitting conductive layer. Thereby, the conductive path is provided, and the formation region of the reflection structure can be increased in a plan view from the light extraction surface 18. Further, the metal electrode layer 23 is provided on the uppermost surface side of the reflection structure group 34 as in the first embodiment.

(Embodiment 3)
Furthermore, FIG. 9 shows another embodiment of the reflecting structure. The light emitting element according to the third embodiment is different from the light emitting element according to the second embodiment only in the reflection structure, and the other structures are substantially the same. Therefore, in the light emitting element 30 according to Embodiment 3, the same components as those of the light emitting element 20 according to Embodiment 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the example of FIG. 9, both the first reflective layer 4 a and the second reflective layer 4 b are not connected in the stacking direction (up and down direction in FIG. 9), but are separated from each other and alternately arranged in parallel in the horizontal direction. . However, the parallel order of both the reflective layers is not limited alternately, and the formation area of each reflective layer can be determined so as to correspond to the distribution ratio of the component light constituting the mixed color. Are formed at an arrangement in which both reflection layers are evenly mixed and the color unevenness due to the parts is reduced. In addition, since both the reflective layers are separated in a vertical manner without being stacked vertically, the reflective structure can be made thin. As a result, the light-emitting element and the light-emitting device can be thinned.

(Embodiment 4)
Furthermore, FIG. 10 shows another embodiment of the reflecting structure. The light-emitting element according to Embodiment 4 is different from the light-emitting element according to Embodiment 2 only in the reflective structure, and the other structures are substantially the same. Therefore, in the light emitting element 40 according to the fourth embodiment, the same components as those of the light emitting element 20 according to the second embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the example of FIG. 10, the first reflective layer 4 a and the second reflective layer 4 b separated from each other have a reflective structure group 34 that is displaced in the horizontal direction and is stacked vertically. That is, the reflective structure group 34 includes a first-stage reflective structure group 34A in which the first reflective layer 4a having the same center wavelength is formed horizontally, and an opening of the first reflective layer 4a. The second reflective layer 4b is formed horizontally with the second region 4b centered on the partial region, and is laminated via the translucent conductive layer 13 as in the third embodiment. In other words, the second reflective layer 4b is arranged so as to fill the space between the first reflective layers 4a in a plan view from the surface side of the electrode 3. With this structure, it is possible to obtain an element having desired characteristics by arranging the reflecting structure in a planar and three-dimensional manner.

  In the example of FIG. 10, the center wavelengths of the reflective layers arranged horizontally in each stage are the same. However, as shown in FIG. 9, the center wavelengths of the adjacent reflective layers may be different. A reflective layer group composed of reflective layers may be formed in a plurality of stages.

(Comparative example 1, Examples 1-5)
The light emitting elements having different reflection structures are obtained by the above procedure. The light emitting elements of Comparative Example 1 and Examples 1 to 5 are □ 1 mm LEDs, and include a dielectric multilayer film in a reflective structure. The electrode structure has a reflective structure in which a light-transmitting conductive layer (ITO) is provided on each conductive type semiconductor layer and an insulating film (SiO ₂ ) / dielectric multilayer film is laminated in this order. Each of the light emitting elements of Comparative Example 1 and Examples 1 to 5 is different in the configuration of the dielectric multilayer film 4 and the other structure is substantially the same as the above light emitting element. Omitted.

As shown in FIG. 6, the reflecting structure has square dot-shaped openings each having a side of 10 μm, and these openings are arranged at lattice-like lattice points. The distance between adjacent dots is 30 μm. In addition, the dielectric multilayer film is formed on a light-transmitting conductive layer (ITO) of about 60 nm formed on the nitride semiconductor layer via an insulating film (SiO ₂ ) of about 0.5 μm. Constitutes a reflective structure. Further, on the surface side of the dielectric multilayer film 4, a metal electrode layer made of Ti—Rh is laminated as an external electrode connection region to constitute an electrode, and a reflective structure opening 35 provided in a part thereof. Conductive to the translucent conductive layer. As shown in the cross-sectional view of FIG. 3, the insulating film 16 is formed on the exposed surface of the semiconductor structure 11 and is used in combination with the protective film. That is, the protective film and the insulating film are not provided in separate steps, and both are formed in the same step and the same material. Further, in this embodiment, the reflection structure is provided on the substantially entire surface of the exposed portion of the semiconductor layer by providing an opening serving as a conductive portion with the external electrode 23 on the translucent conductive layer.

The reflective structure of Comparative Example 1 includes only the first reflective layer 4a having a reflective characteristic corresponding to the light emission peak spectrum of the light source. Specifically, in the first reflective layer 4a, four pairs of two-layer films composed of Nb ₂ O ₃ and SiO ₂ are stacked, and the central wavelength of each reflection is set to 460 nm.

  In addition to the center wavelength (460 nm) of the first reflective layer, which is the light emission peak wavelength of the LED, the dielectric multilayer film according to Example 1 further has a reflection characteristic on the longer wavelength side than the peak wavelength. It consists of a reflective layer. The center wavelength of the second reflective layer is in a wavelength region that is excited by the light source and wavelength-converted. However, the half width at the emission peak of the converted light on the long wavelength side (wavelength of about 560 nm) is wider than the half width at the emission peak of the LED light on the short wavelength side. For this reason, the center wavelength of the second reflective layer is set to the longer wavelength side. In Example 1, the center wavelength of the second reflective layer is 575 nm, that is, 1.25 times the center wavelength of the first reflective layer. Further, similar to the peak wavelength of the LED light and the converted light according to Example 1, the hues corresponding to the center wavelengths of the respective reflective layers are different from each other, and both have a complementary color relationship.

  The dielectric multilayer film according to Example 2 corresponds to the first reflective layer having a reflection characteristic of 368 nm corresponding to 0.8 times the light source wavelength (460 nm) and 1.2 times the light source wavelength (460 nm). And a second reflection layer having a reflection characteristic of 552 nm.

Furthermore, the dielectric multilayer films of Examples 3 to 5 are each composed of a reflective layer having three central wavelengths. Specific center wavelengths and the number of stacked pairs in each reflective layer when the light source wavelength (460 nm) is used as a reference are as follows.
Example 3: First reflective layer (368 nm (0.8 times)) 2 pairs / third reflective layer (460 nm (1.0 times)) 2 pairs / second reflective layer (552 nm (1.2 times)) 2 Pair Example 4: First reflective layer (431 nm (0.9375 times)) 3 pairs / third reflective layer (518 nm (1.125 times)) 3 pairs / second reflective layer (621 nm (1.35 times)) Example 3: First reflective layer (437 nm (0.95 times)) 3 pairs / third reflective layer (529 nm (1.15 times)) 3 pairs / second reflective layer (621 nm (1.35 times)) 3 pairs In addition, each dielectric multilayer film of Examples 1-5 is set to each central wavelength by changing the film thickness of a two-layer film made of the same material as that of Comparative Example 1.

  Here, in Examples 3 to 5, in addition to the second reflective layer, a third reflective layer having a shorter wavelength than the peak wavelength of the converted light, that is, a center wavelength between the peak wavelengths of the LED light and the converted light is provided. The second reflective layer has a center wavelength longer than the third reflective layer and further from the peak wavelength of the converted light. In Examples 2 to 5, the first reflective layer has a wavelength shorter than the peak wavelength of the LED light as the center wavelength.

In addition, the light emission characteristics, drive voltage, light emission output φ _e , external emission obtained by mounting the light emitting elements of Comparative Example 1 and Examples 1 to 5 on light emitting devices that differ in the presence or absence of a phosphor as a wavelength conversion member, Table 1 shows the quantum efficiency ηex, the center wavelength λ _d , the luminous flux φ _v , the power efficiency WPE (Watt Per Energy), and the light emission efficiency (lm / W). The output ratio and the luminous flux ratio in Table 1 are indicated by the ratio to the value of Comparative Example 1, [Each Example] / [Comparative Example 1]. Moreover, the graph of the reflectance of the reflection structure of the light emitting element which concerns on FIG. 11 at the comparative example 1 and Examples 1-5 is shown. FIG. 12 shows emission spectra in the light emitting devices of Examples 1 and 2 and Comparative Example 1. In the table, the light-emitting device indicated as “device B” is a light-emitting device as shown in FIG. 1, and two light-emitting elements of each of the implementation and comparative examples are connected in series to the submount. Thus, the wavelength conversion member is coated with resin and emits white light. In the table, “apparatus A” means that one light-emitting element is mounted in a cup of one set of mounting leads out of a set of two leads for each polarity (a total of four leads). It is a blue light emitting device obtained by sealing with a lens integrated. The same applies to Table 2.

  As shown in Table 1, in any light emitting device of any of the examples, in the light emitting device containing the wavelength conversion member, the light emission characteristics are improved as compared with Comparative Example 1, and the luminous flux ratio with the comparative example is also improved. In other words, in a light emitting device that emits only a single hue, the improvement in light emission characteristics does not depend on the number of central wavelengths in the reflective layer, but in a light emitting device that can emit wavelengths corresponding to a plurality of hues, By having the reflective layer corresponding to the hue, the light emission characteristics are improved by about 5 to 10% (see the presence of the wavelength conversion member in Table 1). Comparison of Examples 1 and 2 improves the light emission characteristics even when the center wavelength of the first reflective layer corresponding to the light source is shifted to the short wavelength side and the wavelength range with the center wavelength of the second reflective layer is expanded. Is made. Specifically, the center wavelength of the first reflective layer is set to 0.8 to 1.0 times the wavelength of the light source, and / or the center wavelength of the second reflective layer is 1.20 times to 1 The effect described above is remarkably obtained by setting the wavelength difference of .35 times or less and separating the wavelength difference between the central wavelengths of the respective reflective layers. Therefore, the central wavelength of the first and second reflective layers is made larger than the peak wavelength range of the LED light and the converted light, and preferably the central wavelength of the first reflective layer on the short wavelength side is made larger than the peak wavelength of the LED light The center wavelength of the second reflection layer on the long wavelength side is set to be the same as or longer than the peak wavelength of the converted light, for example, the peak side (half value of the peak value) from the wavelength that is half the converted light peak. The above wavelength range), specifically, the peak wavelength is preferably included in a range of ± 20 nm. More preferably, the LED light peak wavelength and the converted light peak wavelength or a part of the wavelength range of half or more of the peak value is included between the center wavelengths of the first and second reflective layers, specifically, 1/4 of the wavelength range. The above is included. In this manner, the center wavelength of the conventional multilayer reflective layer is made to correspond to a component having a high incident angle, that is, a wavelength longer than the wavelength of the LED light is added, or the band is widened to the longer wavelength side. Compared to the structure, the present invention has a short wavelength side central wavelength (first reflective layer), and between the central wavelengths of the reflective layer, LED peak-converted light peak or LED peak wavelength-converted light. This is different in that it is spaced apart from the half-wavelength on the short wavelength side, thereby improving the characteristics of the light-emitting element and the light-emitting device. Specifically, the distance between the central wavelengths of the first and second reflective layers in each example is 115 nm in Example 1, and in Examples 2, 3, and 5, compared to the distance between the LED-converted light peak (about 100 nm). 184 nm, 190 nm in Example 4, and the ratio thereof [between the central wavelengths of the first and second reflective layers] / [between LED and converted light peak] are 1.15, 1.84, and 1.90. From this, it is understood that the ratio between the LED-converted light peak and the center wavelength of the first and second reflective layers should be about 1.1 to 3 times, preferably about 1.3 to 2.5 times. .

  In Examples 3 to 5, in addition to the first and second reflective layers, the third reflective layer has a central wavelength between the central wavelengths of the first and second reflective layers at both ends of the wavelength range. Example 3 has a third reflective layer corresponding to the LED light peak wavelength in Example 2, and Example 4 has a short wavelength side of the LED light peak wavelength and a long wavelength side of the converted light peak wavelength as in Example 2. In addition to the corresponding first and second reflective layers, a third reflective layer substantially corresponding to the converted light peak wavelength is provided, and Example 5 has a distance between the center wavelengths of the first and second reflective layers as compared with Example 2. As the same, both ends of the center wavelength are set to the longer wavelength side. Compared with Example 2, Examples 3 and 4 tend to decrease the luminous flux and its ratio, but Example 3 has a particularly large decrease. From this, it is preferable that the third reflective layer is provided in a region between the LED and the converted light peak, which is longer than the center between the LED and the converted light peak (490 nm), between the center wavelengths of the first and second reflective layers. The longer wavelength side than the center (529 nm in Example 5) is preferable.

(Comparative Examples 2-3, Examples 6-7)
Furthermore, in the reflective structures of Comparative Examples 2-3 and Examples 6-7, compared with Example 1 above, the light-transmitting conductive layer (ITO) having a film thickness of about 50 nm and the dielectric multilayer film layer There is a difference in the presence or absence of an insulating film (SiO ₂ ). The opening pattern of the dielectric multilayer film having a reflective structure is formed in the same dot shape as in the first embodiment.

  Specifically, the reflective structures of Comparative Example 2 and Example 6 are configured by only the first reflective layer having the central wavelength of reflection of 460 nm, similar to Comparative Example 1 described above. However, Comparative Example 2 does not include an insulating film, while the light-emitting element of Example 6 includes an insulating film. In addition, the reflection structures of Comparative Example 3 and Example 7 are 0.7 to 1.2 times with respect to the light source (460 nm), and one layer having a center wavelength corresponding to each tolerance of 0.1 is provided. A total of 6 pairs are stacked one by one. That is, it has a plurality of reflective layers. However, Comparative Example 3 does not include an insulating film, while the light-emitting element of Example 7 has an insulating film. Table 2 shows light emission characteristics obtained by mounting each light emitting element on a light emitting device containing a wavelength conversion member. From Table 2, in the electrode structure having the insulating film, the light emission characteristics are improved regardless of the reflection structure.

The light emitting device of the present invention can be suitably used for illumination light sources, LED displays, backlight light sources, traffic lights, illumination switches, various sensors, various indicators, and the like.

1 is a schematic cross-sectional view of a light emitting device according to Embodiment 1. FIG. 3 is a partially enlarged cross-sectional view of the light emitting device according to Embodiment 1. FIG. 3 is a cross-sectional view of the light-emitting element according to Embodiment 1. FIG. FIG. 6 is an explanatory diagram illustrating a manufacturing process of the light emitting element according to Embodiment 1 in which a reflective structure is formed. It is a schematic plan view showing an example in which a dielectric multilayer film is provided on the upper surface of a translucent conductive layer. FIG. 6 is a schematic plan view showing another example in which a dielectric multilayer film is provided on the upper surface of a translucent conductive layer. 6 is a schematic diagram showing a method for manufacturing the light emitting device according to Embodiment 1. FIG. 4 is a cross-sectional view of a light emitting element according to Embodiment 2. FIG. 6 is a cross-sectional view of a light-emitting element according to Embodiment 3. FIG. 6 is a cross-sectional view of a light emitting element according to Embodiment 4. FIG. It is a graph which shows the reflectance in the reflection structure of the comparative example 1 Examples 1-5. It is an emission spectrum figure of the light-emitting device which concerns on an Example and a comparative example. It is sectional drawing which shows the conventional light emitting element.

DESCRIPTION OF SYMBOLS 1 ... Light-emitting device 3 ... Electrode 3A ... 1st electrode (n-type pad electrode)
3B ... Second electrode (p-type pad electrode)
4 ... Reflective structure (dielectric multilayer)
4a ... 1st reflective layer 4b ... 2nd reflective layer 5 ... Growth substrate (sapphire substrate)
6: First nitride semiconductor layer (n-type semiconductor layer)
6a ... n-type contact layer 7 ... second nitride semiconductor layer (p-type semiconductor layer)
8 ... Light emitting layer (active layer)
9 ... Wiring board (submount board)
10, 20, 30, 40 ... Light emitting device (nitride semiconductor device)
11 ... Semiconductor structure (nitride semiconductor layer)
12 ... Wavelength conversion member (phosphor)
13 ... translucent conductive layer (translucent electrode, ITO)
14 ... Protective film 16 ... Insulating film (protective film)
DESCRIPTION OF SYMBOLS 18 ... Light extraction surface 19 ... Interface 21, 22 ... Opening part of protective film 23 ... Metal electrode layer 24 ... Conductive member (bump)
25 ... Wafer 26 ... Coating layer (resin)
DESCRIPTION OF SYMBOLS 27 ... Support body 28 ... Eutectic layer 29 ... Electrode 31 of support body ... Wire bonding 32 ... Conduction path 34 ... Reflection structure group 34A ... First-stage reflection structure group 34B ... Second-stage reflection structure group 35 ... Opening 36 ... Lens 100 ... Light emitting device 101 ... Substrate 102 ... n-type semiconductor layer 103 ... Light emitting layer 104 ... p-type semiconductor layer 105 ... p-side electrode 105a ... Ag layer 105b ... Metal layer 106 ... n-side electrode

Claims (10)

A semiconductor structure having a light emitting layer;
A light extraction surface provided on one main surface side of the semiconductor structure;
An electrode provided on the other main surface side of the semiconductor structure and electrically connected to the semiconductor structure;
A light emitting device having
Wherein arranged so as to cover the periphery of the light emitting element, a conversion wavelength converting member wavelength of the light emitted from the light emitting element,
A light emitting device comprising:
A reflective structure is formed between the semiconductor structure and the electrode;
The reflective structure includes a first reflective layer that reflects a central wavelength corresponding to a wavelength of light from the light emitting layer, and a wavelength conversion by the wavelength conversion member that is laminated between the first reflective layer and the electrode. A second reflective layer that reflects a central wavelength longer than the central wavelength of the first reflective layer, corresponding to the wavelength of the emitted light,
The center wavelength of at least one of the first reflective layer and the second reflective layer is a visible light region,
The central wavelength of the first reflective layer and the second reflective layer have different colors from each other, Ri near relationship complementary,
The reflective structure, light-emitting device according to claim dielectric multilayer der Rukoto as a laminate of a material layer composed of two or more. The light-emitting device according to claim 1.
The center wavelength of the first reflective layer is shorter than the wavelength of light from the light emitting layer;
The light emitting device characterized in that a center wavelength of the second reflective layer is longer than a wavelength of light from the light emitting layer. The light-emitting device according to claim 1 or 2,
The center wavelength of the reflected light of the first reflective layer is 0.8 times or more and less than 1.0 times the wavelength of the light from the light emitting layer,
The light emitting device characterized in that the central wavelength of the reflected light of the second reflective layer is 1.15 to 1.40 times the wavelength of the light from the light emitting layer. The light emitting device according to any one of claims 1 to 3,
The light emitting device, wherein a wavelength of light emitted from the light emitting layer is 360 nm to 650 nm. The light emitting device according to any one of claims 1 to 4,
The reflective structure further includes a third reflective layer,
A light emitting device, wherein a central wavelength of reflected light of the third reflective layer is in a wavelength region between the central wavelengths of the first reflective layer and the second reflective layer. The light emitting device according to any one of claims 1 to 5,
A plurality of the reflection structures arranged in a horizontal direction with a predetermined interval are laminated in a plurality of stages, spaced apart from each other substantially in parallel,
The light emitting device according to claim 1, wherein each of the reflective structure groups in each stage is formed with an upper reflective structure so as to cover at least a part of an opening in a horizontally spaced region of the reflective structure positioned in the lower stage. The light emitting device according to any one of claims 1 to 6,
The light-emitting device, wherein the reflection structure is formed on at least a side surface of the semiconductor structure with an insulating film interposed therebetween. The light emitting device according to any one of claims 1 to 7,
The main surface of the semiconductor structure is covered with a translucent conductive layer, and the reflective structure is formed on at least a part of the translucent conductive layer,
The light emitting device, wherein the electrode includes a metal electrode layer in contact with the reflective structure and the translucent conductive layer. The light emitting device according to any one of claims 1 to 8,
The light emitting device, wherein the wavelength conversion member is disposed in contact with or close to a light extraction surface of the light emitting element. The light emitting device according to any one of claims 1 to 9,
The light emitting element is an LED having an emission peak wavelength at 360 nm to 800 nm,
The wavelength conversion member includes at least one phosphor selected from the group consisting of LAG, BAM, BAM: Mn, YAG, CCA, SCA, SCESN, SESN, CESN, CASBN, and CaAlSiN ₃ : Eu. A light emitting device.

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