JP2003243726A - Light emitting device and manufacturing method thereof - Google Patents

Abstract

(57) Abstract: To efficiently convert generated short-wavelength light (ultraviolet light) into visible light or the like with a phosphor and to extract the light efficiently to the outside. A nitride semiconductor light-emitting device having a p-type layer, a negative electrode, a positive electrode, and a light-emitting layer interposed between the n-type layer and the p-type layer; and a particulate phosphor on the nitride semiconductor light-emitting device. In the light emitting device having the coating layer, the surface of the nitride semiconductor light emitting element has a concave portion and an island portion, and the concave portion has an opening in which the minimum value of the interval between the concave side surfaces is larger than the average particle size of the particulate phosphor. Has,
A light-emitting device characterized in that one or more particulate phosphors are housed therein. The method for forming a coating layer further includes a step of spraying a coating liquid containing a phosphor from above the light emitting element while rotating the liquid in a mist and spirally.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device having a gallium nitride compound semiconductor, and more particularly to a structure for irradiating a phosphor with light emitted from the light emitting device to obtain light emission of a desired wavelength.

[0002]

2. Description of the Related Art In recent years, a light emitting device made of a gallium nitride compound semiconductor has been developed, and it is possible to form a light emitting device using ultraviolet light or blue light having high emission intensity from the light emitting device as an excitation light source for a phosphor. It is becoming possible. When the light emitted from such a light emitting element is wavelength-converted by a phosphor and is extracted to the outside of the light emitting device, the phosphor is generally mixed in a resin mold that covers the light emitting element (see, for example, Patent Document 1). .

[0003]

[Patent Document 1] Japanese Patent Application No. 10-357643

[0004]

However, when a phosphor is contained in the resin mold, most of the light emitted from the light emitting element is not immediately wavelength-converted by the phosphor, and the light is transmitted through the resin mold portion. The wavelength is generally converted by the phosphor as it goes. Therefore,
Since the light from the light emitting element is gradually attenuated as it propagates through the resin mold, wavelength conversion by the phosphor cannot be efficiently performed in the above configuration. Further, there is also a problem that short-wavelength light (visible light to near-ultraviolet light) causes color deterioration of a resin mold containing an organic compound as a main component.

The present invention has been made to solve the above-mentioned problems, and its main purpose is to efficiently convert light of a short wavelength into a visible light or the like with a phosphor and take it out to the outside. Another object of the present invention is to provide a highly reliable light emitting device capable of emitting three primary colors of red, green, and blue.

[0006]

In order to achieve the above object, a light emitting element having at least an n-type layer having a negative electrode and a p-type layer having a positive electrode, and at least one of light emitted from the light emitting element. In a light emitting device having a particulate fluorescent material that absorbs light having a different wavelength by absorbing a portion, the light emitting element has a recess (110) on a surface of the light emitting element,
It is a light-emitting device having the particulate fluorescent material in the recess.

According to the first aspect of the present invention, since one or more particles of the particulate phosphor are contained in the concave portion of the surface of the light emitting element, the distance between the light emitting portion inside the light emitting element and the particulate phosphor is determined by the prior art. It is possible to get closer. Therefore, the light emitted from the light emitting layer of the light emitting element is easily converted into visible light immediately by the particulate fluorescent substance in the recess without being attenuated during propagation in the recess, so that the conversion efficiency to visible light is high. ,
It is possible to efficiently obtain a sufficient level of visible light. Further, since the contact area between the particulate phosphor and the surface of the light emitting element is increased, the conversion efficiency of the particulate phosphor into visible light is further increased, and a sufficient level of visible light can be efficiently obtained.

A second invention is the light emitting device according to claim 1, wherein the recess (110) has a mesa-shaped side surface.

According to the second aspect of the invention, the light emitted from the light emitting layer of the light emitting element is not totally reflected by the inner wall surface of the recess, but is refracted into the recess by utilizing the refraction of the light on the side surface of the mesa. Then, the light whose wavelength is converted by the phosphor is efficiently extracted to the outside of the light emitting device. Therefore, the conversion efficiency of visible light by the phosphor is higher, the light extraction efficiency is improved,
Further, it is possible to efficiently obtain a sufficient level of visible light.

A third aspect of the present invention is the light emitting device according to claim 1 or 2, wherein the recess (110) is provided at least continuously with the p-type layer and the positive electrode.

According to the third aspect of the invention, it is possible to reduce the amount of the particulate fluorescent substance existing on the positive electrode as much as possible and increase the amount of the fluorescent substance existing in the concave portion. That is, since the positive electrode does not easily transmit the light emitted from the light emitting layer, even if the particulate fluorescent substance is present on the positive electrode, the fluorescent substance does not perform the function of wavelength conversion and is wasted. I will end up. Therefore, when forming a coating layer containing a phosphor on the positive electrode side, the amount of the particulate phosphor existing on the positive electrode is reduced as much as possible, and the amount of the phosphor existing in the recess is increased, whereby The conversion efficiency of visible light by the body becomes higher, and a sufficient level of visible light can be obtained efficiently.

A fourth invention is the light-emitting device according to any one of claims 1 to 3, wherein the concave portion (110) is provided continuously with at least the n-type layer and the negative electrode.

According to the fourth aspect of the invention, when the coating layer containing the particulate phosphor is formed on the n-type layer side of the nitride semiconductor light emitting device, the contact area between the phosphor and the n-type layer increases. As a result, the conversion efficiency of the fluorescent substance into visible light becomes higher, and a sufficient level of visible light can be obtained efficiently. Further, the same effect as the third invention can be obtained.

A fifth aspect of the present invention is a method for manufacturing a light emitting device having a concave portion (110) on the surface and a particulate fluorescent substance in the concave portion, wherein the distance between the concave inner walls (101) is the minimum. A first step of forming a recess (110) having a value larger than the average particle diameter of the particulate phosphor in the light emitting element, and a second step of dropping a coating liquid containing the particulate phosphor onto the light emitting element. And a third step of drying the coating liquid in which the particulate phosphor is settled, which is a method for manufacturing a light emitting device.

According to the fifth aspect of the invention, since the particulate phosphor has a large specific gravity in the coating liquid, it is more likely that it will settle below the coating liquid and be settled in the recess. Therefore, the conversion efficiency of the fluorescent substance into visible light becomes higher, and it becomes possible to easily manufacture a light emitting device capable of efficiently obtaining a sufficient level of visible light.

A sixth aspect of the present invention is a method for manufacturing a light emitting device having a concave portion (110) on the surface and a particulate fluorescent substance in the concave portion, wherein the distance between the inner walls of the concave portion (101) is minimum. A first step of forming a recess (110) in the light-emitting element, the value of which is larger than the average particle diameter of the particulate phosphor; and, in a state where the light-emitting element is heated, the phosphor is removed from above the light-emitting element. A method for manufacturing a light-emitting device, comprising: a second step of spraying the contained coating liquid while rotating it in a mist and spirally; and a third step of drying the coating liquid.

According to the sixth aspect of the invention, since it is possible to ensure that the particulate fluorescent material is present even at the corner where the upper surface of the concave portion and the side surface of the island portion intersect, conversion of the fluorescent material into visible light is performed. The efficiency becomes higher, and it becomes possible to easily obtain a light emitting device capable of efficiently obtaining a sufficient level of visible light. Furthermore, according to the present invention, since it is possible to apply the phosphor in a semiconductor wafer state which is in the process of manufacturing the light emitting device, the intensity of the light whose wavelength is converted by the applied phosphor is changed to the semiconductor wafer state. It can also be measured at. Therefore, it is possible to easily select chips in a wafer state, and it is possible to improve the mass productivity and the manufacturing yield of semiconductor light emitting devices.

In a seventh aspect of the invention, in the first step,
7. The method for manufacturing a light emitting device according to claim 5, wherein the recesses are formed at intervals smaller than the average particle diameter of the particulate phosphor.

According to the seventh aspect of the present invention, when the coating liquid containing the particulate phosphor is applied to the surface of the light emitting element, the particulate phosphor is unlikely to remain on the upper surface of the island formed between the recesses, and It is easy to fit in. Therefore, it is possible to increase the probability of accommodating the particulate fluorescent material in the concave portion, the conversion efficiency of the fluorescent material into visible light is higher, and it is easy to realize a light emitting device that can efficiently obtain a sufficient level of visible light. Can be manufactured.

In an eighth invention, the coating liquid is at least Si, Al, Ga, Ti, Ge, P, B, Zr, Y, S.
8. A light emitting device according to claim 5, which is a solution containing an organometallic compound containing one or more elements selected from the group consisting of n, Pb, and alkaline earth metals, an organic solvent, and a phosphor. Is the way.

According to the eighth aspect of the present invention, the short wavelength light (ultraviolet light) from the light emitting element can be efficiently wavelength-converted into visible light or the like and can be efficiently extracted to the outside.
The material that binds the phosphor is short-wavelength light (ultraviolet light),
Alternatively, it is possible to manufacture a highly reliable light emitting device which is not deteriorated by high-power light.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. However, the embodiments described below exemplify a light emitting device for embodying the technical idea of the present invention, and the present invention does not limit the light emitting device to the following. Further, the size and positional relationship of members shown in each drawing are exaggerated for clarity.

1, 2, and 4 are schematic cross-sectional views showing a structural example of a light emitting device according to an embodiment of the present invention, and FIG. 3 is a top view. The light emitting device according to the present invention is
A concave portion and an island portion are formed in a part of the electrode of the light emitting element and / or the laminated body of the semiconductor, and at least a particulate phosphor that absorbs at least a part of light from the light emitting element and emits light having different wavelengths is used. It has in the recess.

The term "island portion" as used herein refers to an island-like portion left between the recess and the recess adjacent to the recess when the recess is formed on the surface of the light emitting element. The recess in the present invention has a minimum value r _min of the space between the recess inner walls 101 (see FIG. 5).
(Shown in (d)) is formed to be larger than the average particle size of the particulate phosphor. Alternatively, the particulate phosphor 103 in the present invention is formed such that its average particle size is smaller than the minimum value r _min of the interval between the recess inner walls 101.
By forming in this way, the concave portion 110 can house the particulate phosphor of one or more particles inside. Further, the recesses 110 are preferably formed at intervals smaller than the average particle diameter of the particulate phosphor (so that the width of the island 111 is smaller than the average particle diameter of the particulate phosphor). By using the light-emitting element formed in this way, the particulate phosphor can be easily accommodated in the recess in the manufacturing process of the light-emitting device of the present invention.

With the above-described structure, the probability that one or more particles of the particulate phosphor will exist in the recess increases, and the light emitted from the light-emitting layer is in contact with the inner wall and the bottom of the recess. Since it is immediately converted into visible light, the conversion efficiency into visible light is high, and a sufficient level of visible light can be efficiently obtained.

Hereinafter, each configuration of the embodiment of the present invention will be described in detail. [LED Chip] The LED chip used as the light emitting element in the present embodiment is capable of exciting the phosphor provided in the light emitting device. LED chip is MOC
GaAs, InP, GaAlA on the substrate by VD method etc.
s, InGaAlP, InN, AlN, GaN, InG
A semiconductor such as aN, AlGaN, InGaAlN is formed. Examples of the structure of the semiconductor include a homo structure having a MIS junction, a PIN junction and a PN junction, a hetero structure, or a double hetero structure. Various emission wavelengths can be selected depending on the material of the semiconductor layer and the degree of mixed crystal thereof. Further, the semiconductor active layer may be formed as a thin film in which a quantum effect is generated, and may have a single quantum well structure or a multiple quantum well structure. Preferably, a nitride-based compound semiconductor (general formula In _i Ga _j Al _k N, where 0 ≦ i, 0 ≦, which can efficiently emit a relatively short wavelength that can efficiently excite a phosphor).
j, 0 ≦ k, i + j + k = 1).

When a gallium nitride compound semiconductor is used, sapphire, spinel, SiC, S are used as the semiconductor substrate.
Materials such as i, ZnO and GaN are preferably used. It is more preferable to use a sapphire substrate in order to form gallium nitride having good crystallinity. When growing a semiconductor film on a sapphire substrate, it is preferable to form a buffer layer of GaN, AlN or the like, and to form a gallium nitride semiconductor having a PN junction thereon. In addition, GaN selectively grown on a sapphire substrate using SiO ₂ as a mask.
The single crystal itself can also be used as the substrate. In this case, the light emitting element and the sapphire substrate can be separated by etching away SiO ₂ after forming each semiconductor layer. The gallium nitride-based compound semiconductor exhibits N-type conductivity in a state where it is not doped with impurities. In the case of forming a desired N-type gallium nitride semiconductor such as improving the luminous efficiency, Si, Ge, Se, N
It is preferable to introduce Te, C and the like as appropriate. On the other hand, when forming a P-type gallium nitride semiconductor, P-type dopants such as Zn, Mg, Be, Ca, Sr, and Ba are doped.

The gallium nitride-based compound semiconductor is difficult to become P-type by only doping with a P-type dopant, so that after the P-type dopant is introduced, it is annealed by heating in a furnace, low-speed electron beam irradiation, plasma irradiation, or the like to make it P-type. It is preferable. As a specific layer structure of the light emitting element, an N-type contact layer which is a gallium nitride semiconductor, an aluminum nitride / gallium semiconductor is provided on a sapphire substrate having a buffer layer formed of gallium nitride, aluminum nitride, or the like at low temperature or silicon carbide. A laminated N-type clad layer, an active layer that is an indium gallium nitride semiconductor doped with Zn and Si, a P-type clad layer that is an aluminum nitride / gallium semiconductor, and a P-type contact layer that is a gallium nitride semiconductor. Are preferred. LED
In order to form the chip 103, in the case of the LED chip 103 having a sapphire substrate, after forming exposed surfaces of the P-type semiconductor and the N-type semiconductor by etching or the like, a sputtering method or a vacuum deposition method is used on the semiconductor layer. Then, each electrode having a desired shape is formed. In the case of SiC substrate,
The pair of electrodes can be formed by utilizing the conductivity of the substrate itself.

Next, the formed semiconductor wafer or the like is directly full-cut by a dicing saw in which a blade having a diamond edge is rotated, or after a groove having a width wider than the edge width is cut (half-cut), The semiconductor wafer is broken by an external force. Alternatively, an extremely thin scribe line (meridian line) is drawn in a semiconductor wafer, for example, in a grid pattern by a scriber in which a diamond needle at the tip moves reciprocally in a straight line, and then the wafer is split by external force to be cut into chips. In this way, the LED chip 103, which is a nitride-based compound semiconductor, can be formed.

When light is emitted from the light emitting device of the present invention, the main emission wavelength of the LED chip is preferably 350 nm or more and 530 nm or less in consideration of the complementary color with the phosphor.

Furthermore, in order to form recesses and islands on the surface of the LED chip, after patterning, wet etching is performed with HCl or the like using a resist as a mask, and then dot, stripe or concentric circles are formed by RIE or the like. A concave portion or a plurality of circular concave portions is formed in the n-type layer, the p-type layer, the negative electrode and / or the positive electrode.
The recess has an opening in which the minimum value r _min (illustrated in FIG. 5D) of the space between the recess side surfaces 101 is larger than the average particle diameter of the particulate phosphor, and the inside of the particulate phosphor is It should be possible to store more than particles. As a result, since one or more particles of the particulate phosphor are contained in the concave portion on the surface of the light emitting device,
It is possible to reduce the distance between the light emitting layer and the particulate phosphor. Therefore, the light emitted from the light emitting layer is immediately converted into visible light by the particulate fluorescent material in the recess, so that the conversion efficiency into visible light is high and a sufficient level of visible light can be obtained efficiently. Further, in the present invention, it is preferable that the size of the upper surface of the island portion is smaller than the size of the particulate phosphor having the average particle diameter. If such an island portion is provided, when the coating liquid containing the phosphor is applied to the upper surface of the light emitting element, the particulate phosphor is less likely to stay on the upper surface of the island portion and easily fit in the recess. Therefore, it is possible to increase the probability that the particulate fluorescent material is housed in the concave portion, the conversion efficiency of the fluorescent material into visible light is higher, and it is possible to efficiently obtain a sufficient level of visible light. [Phosphor] The phosphor used in the present invention means a phosphor that emits light by being excited by at least light emitted from the LED chip. In the present embodiment, a phosphor that is excited by ultraviolet light to generate light of a predetermined color can also be used as the phosphor, and specific examples include (1) Ca ₁₀ (PO ₄ ) ₆ FCl: Sb. , Mn (2) M ₅ (PO ₄ ) ₃ Cl: Eu (where M is Sr,
(3) BaMg ₂ Al ₁₆ O ₂₇ : Eu (4) BaMg ₂ Al ₁₆ O ₂₇ : Eu, Mn (5) 3.5MgO · 0.5MgF ₂ · GeO ₂ : Mn (6) Y ₂ O ₂ S: Eu (7) Mg ₆ As ₂ O ₁₁ : Mn (8) Sr ₄ Al ₁₄ O ₂₅ : Eu (9) (Zn, Cd) S: Cu (10) SrAl _{2 O 4: Eu (11) Ca} 10 (PO 4) 6 ClBr: Mn, Eu (12) Zn 2 GeO 4: Mn (13) Gd 2 O 2 S: Eu, and _{(14) La 2 O 2 S} : Eu Etc.

Further, these phosphors may be used alone or in a mixture in a coating layer consisting of one layer. Further, they may be used alone or as a mixture in a coating layer formed by laminating two or more layers.

When the light emitted by the LED chip and the light emitted by the phosphor have a complementary color relationship, white light can be emitted by mixing the respective lights. Specifically, when the light from the LED chip and the light of the phosphor that is excited and emitted by the LED chip correspond to the three primary colors of light (red, green, and blue), or the blue light emitted by the LED chip, respectively. Examples thereof include light and yellow light of a phosphor that is excited by the light and emits light.

The emission color of the light emitting device can be adjusted by variously adjusting the ratio of the phosphor to various resins acting as a binder for the phosphor, an inorganic member such as glass, the sedimentation time of the phosphor, and the shape of the phosphor. Also, by selecting the emission wavelength of the LED chip, it is possible to provide an arbitrary white color tone such as a light bulb color. It is preferable that the light from the LED chip and the light from the phosphor are efficiently transmitted through the mold member to the outside of the light emitting device.

The phosphor used in this embodiment is a combination of a yttrium-aluminum-garnet-based phosphor and a phosphor capable of emitting reddish light, particularly a nitride phosphor. You can These YAG-based phosphors and nitride-based phosphors may be mixed and contained in the coating layer 108, or may be separately contained in the coating layer 108 composed of a plurality of layers. Hereinafter, each phosphor will be described in detail. (Yttrium / Aluminum / Garnet phosphor)
The yttrium-aluminum-garnet-based phosphor (YAG-based phosphor) used in the present embodiment means Y and A.
at least one element selected from rare earth elements, including at least one element selected from Lu, Sc, La, Gd, Tb, Eu, and Sm, and one element selected from Ga and In. Is a phosphor activated by the element, and is a phosphor that emits light when excited by visible light or ultraviolet light emitted from the LED chip. In particular, in the present embodiment, 2 having different compositions activated by Ce or Pr
More than one type of yttrium-aluminum oxide-based phosphor can also be used. Blue-based light emitted from a light-emitting element using a nitride-based compound semiconductor in the light-emitting layer, and green-based and red-based light emitted from a phosphor whose body color is yellow for absorbing blue light, or When yellowish light and more greenish and reddish light are mixed and displayed, a desired white emission color display can be performed. In order to cause this color mixing, the light emitting device preferably contains the phosphor powder or bulk in various resins such as epoxy resin, acrylic resin or silicone resin, and inorganic substances such as silicon oxide and aluminum oxide. The phosphor-containing material can be used in various ways such as a dot-shaped material or a layer-shaped material formed so thin as to allow light from the LED chip to pass therethrough. It is possible to provide an arbitrary color tone such as an incandescent lamp color including white by adjusting the ratio of the phosphor and the resin, coating and filling amount, and selecting the emission wavelength of the light emitting element.

Further, by arranging two or more kinds of phosphors respectively with respect to the incident light from the light emitting element, it is possible to obtain a light emitting device which can efficiently emit light. That is, on a light emitting element having a reflection member, a color conversion member containing an absorption wavelength on the long wavelength side and containing a phosphor capable of emitting light at a long wavelength, and an absorption wavelength on the longer wavelength side than that, and a longer wavelength. The reflected light can be effectively used by laminating a color conversion member capable of emitting light at a wavelength.

When a YAG type phosphor is used, the irradiance is (Ee) = 0.1 W · cm ⁻² or more and 1000 W · c.
It is possible to obtain a light emitting device having high efficiency and sufficient light resistance even when the light emitting device is arranged in contact with or close to an LED chip of m ⁻² or less.

The YAG phosphor capable of emitting green light, which is the yttrium-aluminum oxide phosphor activated with cerium used in the present embodiment, has a garnet structure and therefore is strong against heat, light and moisture. The peak wavelength of the excitation absorption spectrum can be set to around 420 nm to 470 nm. Also, the emission peak wavelength λp is 510n.
It has a broad emission spectrum that is near m and has a skirt around 700 nm. On the other hand, even a YAG-based phosphor that is a yttrium-aluminum oxide-based phosphor activated by cerium and capable of emitting red light has a garnet structure and is resistant to heat, light, and moisture, and has a peak wavelength of an excitation absorption spectrum of 420 nm. To about 470 nm. Further, it has a broad emission spectrum in which the emission peak wavelength λp is in the vicinity of 600 nm and the tail is extended to the vicinity of 750 nm.

Of the composition of the YAG-based phosphor having a garnet structure, the emission spectrum is shifted to the short wavelength side by substituting a part of Al with Ga, and a part of the Y of the composition is G.
By substituting d and / or La, the emission spectrum shifts to the long wavelength side. If the substitution of Y is less than 20%, the green component is large and the red component is small. On the other hand, when the ratio is 80% or more, the reddish component increases, but the brightness sharply decreases. Similarly, regarding the excitation absorption spectrum, by replacing a part of Al with Ga in the composition of the YAG-based phosphor having a garnet structure, the excitation absorption spectrum shifts to the short wavelength side, and the composition Y Substituting a part of Gd and / or La for the excitation absorption spectrum shifts to the long wavelength side. The peak wavelength of the excitation absorption spectrum of the YAG-based phosphor is preferably on the shorter wavelength side than the peak wavelength of the emission spectrum of the light emitting element. With this configuration,
When the current applied to the light-emitting element is increased, the peak wavelength of the excitation absorption spectrum almost matches the peak wavelength of the emission spectrum of the light-emitting element, so that the chromaticity shift occurs without lowering the excitation efficiency of the phosphor. It is possible to form a light emitting device in which

Such a phosphor is composed of Y, Gd, Ce and L.
An oxide or a compound that easily becomes an oxide at high temperature is used as a raw material of a, Al, Sm, and Ga, and they are sufficiently mixed in a stoichiometric ratio to obtain a raw material. Or Y, Gd, C
e, La, and Sm are mixed by mixing a coprecipitated oxide obtained by firing a solution obtained by coprecipitating oxalic acid with a solution obtained by dissolving a rare earth element of stoichiometric ratio in an acid, aluminum oxide, and gallium oxide. Get the raw materials. An appropriate amount of a fluoride such as ammonium fluoride is mixed in this as a flux, packed in a crucible, and fired in the air at a temperature range of 1350 to 1450 ° C for 2 to 5 hours to obtain a fired product. Ball mill,
It can be obtained by washing, separating, drying and finally sieving. Further, in the method for manufacturing a phosphor according to another embodiment, a mixture of a mixed raw material obtained by mixing the raw materials of the phosphor and a flux is subjected to a first firing step in the air or a weak reducing atmosphere, and in a reducing atmosphere. It is preferable to perform the firing in two stages, which comprises the second firing step performed in 1. Here, the weak reducing atmosphere refers to a weak reducing atmosphere that is set to contain at least the amount of oxygen required in the reaction process for forming a desired phosphor from the mixed raw material. By performing the first firing step until the structure formation of the phosphor is completed, it is possible to prevent the phosphor from being blackened and to prevent the light absorption efficiency from decreasing. The reducing atmosphere in the second firing step means a reducing atmosphere that is stronger than the weak reducing atmosphere. By firing in two stages in this way, a phosphor having a high absorption efficiency of the excitation wavelength can be obtained. Therefore, when a light emitting device is formed with the phosphor thus formed, the amount of the phosphor required to obtain a desired color tone can be reduced, and a light emitting device with high light extraction efficiency can be formed. You can

The yttrium-aluminum oxide-based phosphor activated with two or more kinds of cerium having different compositions is
They may be mixed and used, or may be arranged independently. When arranging each phosphor independently,
It is preferable to arrange a phosphor that easily absorbs and emits light from the light emitting element on the shorter wavelength side and a phosphor that easily absorbs and emits light on the longer wavelength side. This enables efficient absorption and emission of light. (Nitride Phosphor) The first phosphor used in the present invention contains N, and at least one element selected from Be, Mg, Ca, Sr, Ba, and Zn, and C and S.
A nitride-based phosphor containing at least one element selected from i, Ge, Sn, Ti, Zr, and Hf and activated with at least one element selected from rare earth elements. The nitride-based phosphor used in the present embodiment refers to a phosphor that emits light when excited by absorbing visible light, ultraviolet rays, and light emitted from the YAG-based phosphor emitted from the LED chip. Particularly, the phosphor according to the present invention is Sr-Ca-Si-N: E to which Mn is added.
u, Ca-Si-N: Eu, Sr-Si-N: Eu, S
r-Ca-Si-ON: Eu, Ca-Si-ON:
Eu, Sr-Si-O-N: Eu-based silicon nitride. The basic constituent elements of this phosphor are represented by the general formula L _X S
i _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, or Sr and Ca. ). In the general formula, X and Y are X = 2, Y = 5, or X =
It is preferred that 1 and Y = 7, but any can be used. Specifically, the basic constituent elements, Mn is added _{(Sr X Ca 1-X)} 2 Si 5 N 8: Eu, Sr 2 S
i ₅ N ₈ : Eu, Ca ₂ Si ₅ N ₈ : Eu, Sr _X Ca
_1-X Si ₇ N ₁₀ : Eu, SrSi ₇ N ₁₀ : Eu,
Although it is preferable to use a phosphor represented by CaSi ₇ N ₁₀ : Eu, Mg, S, etc. are included in the composition of this phosphor.
At least one selected from the group consisting of r, Ca, Ba, Zn, B, Al, Cu, Mn, Cr and Ni may be contained. However, the present invention is not limited to this embodiment and examples. L is either Sr, Ca, or Sr and Ca. The compounding ratio of Sr and Ca can be changed as desired. By using Si for the composition of the phosphor, it is possible to provide a cheap phosphor having good crystallinity.

Europium Eu, which is a rare earth element, is used as the emission center. Europium mainly has divalent and trivalent energy levels. The phosphor of the present invention uses Eu ²⁺ as an activator with respect to the matrix alkaline earth metal-based silicon nitride. Eu ²⁺ is easily oxidized and trivalent Eu ₂
It is commercially available with a composition of O ₃ . However, commercially available Eu ₂ O
_In No. ₃ , O is largely involved and it is difficult to obtain a good phosphor. Therefore, it is preferable to use Eu ₂ O ₃ after removing O from the system. For example, it is preferable to use europium simple substance or europium nitride. However, this is not the case when Mn is added.

Mn as an additive promotes the diffusion of Eu ²⁺ and improves the luminous efficiency such as luminous brightness, energy efficiency and quantum efficiency. Mn is contained in the raw material, or is contained in the raw material during the manufacturing process, or is burned together with the raw material. However, Mn is not contained in the basic constituent elements after firing, or even if it is contained, only a small amount remains as compared with the initial content. This is probably because Mn was scattered during the firing process. The phosphor contains Mg, Sr, Ca, Ba, Zn, B in the basic constituent elements or together with the basic constituent elements.
It contains at least one selected from the group consisting of Al, Cu, Mn, Cr, O and Ni. These elements have actions such as increasing the particle size and increasing the emission brightness. Also, B, Al, Mg, Cr and N
i has an effect of suppressing afterglow.

Such a nitride phosphor absorbs part of the blue light emitted by the LED chip and emits light in the yellow to red region. The nitride-based phosphor is used together with the YAG-based phosphor in the light-emitting device having the above-mentioned structure to obtain LE.
Provided is a light emitting device which emits warm white light by mixing blue light emitted from a D chip and yellow to red light from a nitride-based phosphor. The phosphor added in addition to the nitride-based phosphor preferably contains a yttrium-aluminum oxide phosphor which is activated by cerium. This is because the chromaticity can be adjusted to a desired level by containing the yttrium aluminum oxide fluorescent substance. The cerium-activated yttrium-aluminum oxide fluorescent material absorbs part of the blue light emitted by the LED chip and emits light in the yellow region. Here, the blue light emitted by the LED chip,
The yellow light of the yttrium-aluminum oxide fluorescent substance is mixed to emit a pale white light. Therefore, the yttrium aluminum oxide phosphor and the phosphor that emits red light are mixed together in the translucent coating layer 108, and the blue light emitted by the LED chip is combined to obtain a white-based phosphor. A light emitting device which emits mixed color light can be provided. Particularly preferred is a white light emitting device whose chromaticity is located on the locus of black body radiation in the chromaticity diagram. However, in order to provide a light emitting device having a desired color temperature, the amount of phosphor of the yttrium-aluminum oxide phosphor and the amount of phosphor of red light emission can be appropriately changed. The light emitting device that emits this white mixed color light is
We are working to improve the special color rendering index R9. A conventional light emitting device that emits white light only by a combination of a blue light emitting element and a yttrium aluminum oxide phosphor activated by cerium has a special color rendering index R9 close to 0 near a color temperature Tcp = 4600K. The redness component was insufficient. Therefore, it has been a problem to be solved to increase the special color rendering index R9. However, by using the red-emitting phosphor with the yttrium aluminum oxide phosphor in the present invention, the special color rendering index near the color temperature Tcp = 4600K. R9 can be increased to around 40.

Next, the phosphor ((Sr _X Ca
_The method for producing _1-X ) ₂ Si ₅ N ₈ : Eu) will be described, but the present invention is not limited thereto. The above phosphor contains M
It contains n and O.

The raw materials Sr and Ca are crushed. Raw material S
R and Ca are preferably used alone, but compounds such as imide compounds and amide compounds can also be used. The raw materials Sr and Ca include B, Al, Cu and M.
It may contain g, Mn, Al ₂ O ₃ , or the like. The raw materials Sr and Ca are pulverized in a glove box in an argon atmosphere. Sr and Ca obtained by crushing are
The average particle size is preferably about 0.1 μm to 15 μm, but is not limited to this range. The purity of Sr and Ca is preferably 2N or more, but not limited to this. Metal Ca, metal S for better mixing
It is also possible to use at least one or more of r and metal Eu as an alloy material after nitriding and crushing.

The raw material Si is crushed. The raw material Si is
It is preferable to use a simple substance, but it is also possible to use a nitride compound, an imide compound, an amide compound, or the like.
For example, Si ₃ N ₄ , Si (NH ₂ ) ₂ , Mg ₂ Si, or the like. Although the purity of the raw material Si is preferably 3N or more, Al ₂ O ₃ , Mg, metal boride (Co ₃ B,
Ni ₃ B, CrB), manganese oxide, H ₃ BO ₃ , B ₂
Compounds such as O ₃ , Cu ₂ O and CuO may be contained. Si is crushed in a glove box in an argon atmosphere or a nitrogen atmosphere, similarly to the raw materials Sr and Ca. The average particle size of the Si compound is about 0.1 μ
It is preferably m to 15 μm.

Next, the raw materials Sr and Ca are nitrided in a nitrogen atmosphere. The reaction formulas are shown in the following formulas 1 and 2, respectively.

3Sr + N ₂ → Sr ₃ N ₂ ... (Equation 1) 3Ca + N ₂ → Ca ₃ N ₂ ... (Equation 2) Sr and Ca in a nitrogen atmosphere at 600 to 900 ° C. 5
Nitriding for hours. Sr and Ca may be mixed and nitrided, or may be individually nitrided. This allows S
A nitride of r and Ca can be obtained. The Sr and Ca nitrides are preferably highly pure, but commercially available ones can also be used.

The raw material Si is nitrided in a nitrogen atmosphere. This reaction formula is shown in Formula 3 below.

3Si + 2N ₂ → Si ₃ N ₄ (Equation 3) Silicon Si is also nitrided in a nitrogen atmosphere at 800 to 1200 ° C. for about 5 hours. Thereby, silicon nitride is obtained. The silicon nitride used in the present invention is preferably highly pure, but commercially available ones can also be used.

The nitride of Sr, Ca or Sr-Ca is crushed. A nitride of Sr, Ca, and Sr-Ca is crushed in a glove box in an argon atmosphere or a nitrogen atmosphere. Similarly, Si nitride is crushed. Similarly, the Eu compound Eu ₂ O ₃ is pulverized. As the compound of Eu, europium oxide is used, but metal europium, europium nitride and the like can also be used. In addition, as the raw material Z, an imide compound or an amide compound can be used. Europium oxide is
A high-purity product is preferable, but a commercially available product can also be used. The average particle size of the crushed alkaline earth metal nitride, silicon nitride and europium oxide is about 0.1 μm.
To 15 μm is preferable.

In the above raw materials, Mg, Sr, Ca, B
At least one selected from the group consisting of a, Zn, B, Al, Cu, Mn, Cr, O and Ni may be contained. Further, the above elements such as Mg, Zn and B can be mixed by adjusting the blending amount in the following mixing step. These compounds can be added to the raw materials alone, but are usually added in the form of compounds. This class of _{compounds, H 3 BO 3, Cu 2} O 3, MgC
l ₂ , MgO · CaO, Al ₂ O ₃ , metal boride (C
rB, Mg ₃ B ₂ , AlB ₂ , MnB), B ₂ O ₃ , C
Examples include u ₂ O and CuO.

After the above pulverization, Sr, Ca, Sr
-Ca nitride, Si nitride, Eu compound Eu ₂ O
Mix ₃ and add Mn. Since these mixtures are easily oxidized, in an Ar atmosphere or a nitrogen atmosphere,
Mix in the glove box.

Finally, a mixture of Sr, Ca, Sr—Ca nitride, Si nitride, and Eu compound Eu ₂ O ₃ is fired in an ammonia atmosphere. Firing the, Mn is added _{(Sr X Ca 1-X)} 2 Si 5 N 8: it is possible to obtain a phosphor represented by Eu. The reaction formula of the basic constituent elements by this firing is shown below.

[0056]

[Chemical 1]

However, the composition of the intended phosphor can be changed by changing the blending ratio of each raw material.

For the firing, a tubular furnace, a small furnace, a high frequency furnace, a metal furnace or the like can be used. The firing temperature is 120
Although firing can be performed in the range of 0 to 1700 ° C,
A firing temperature of 1400 to 1700 ° C is preferred. For the firing, it is preferable to use one-step firing in which the temperature is gradually raised and the firing is performed at 1200 to 1500 ° C. for several hours.
It is also possible to use a two-stage firing (multi-stage firing) in which the first-stage firing is performed at 00 to 1000 ° C., and the second stage is fired at 1200 to 1500 ° C. by gradually heating. The phosphor raw material is preferably fired using a crucible made of boron nitride (BN) or a boat. Besides the crucible made of boron nitride, a crucible made of alumina (Al ₂ O ₃ ) can be used.

By using the above manufacturing method, it is possible to obtain the desired phosphor.

In the present embodiment, a nitride-based phosphor is particularly used as the phosphor that emits reddish light. In the present invention, the above-mentioned YAG-based phosphor and red-based light are used. A light emitting device including a phosphor capable of emitting light can also be used. Such a phosphor that can emit red light is a phosphor that is excited by light having a wavelength of 400 to 600 nm to emit light, and is, for example, Y ₂ O ₂ S: E.
u, La ₂ O ₂ S: Eu, CaS: Eu, SrS: E
u, ZnS: Mn, ZnCdS: Ag, Al, ZnCd
S: Cu, Al, etc. are mentioned. As described above, the color rendering of the light emitting device can be improved by using the phosphor capable of emitting red light together with the YAG phosphor.

Two or more kinds of the phosphors formed as described above may be present in the coating layer consisting of one layer on the surface of the light emitting device, or one kind or two kinds respectively in the coating layer consisting of two layers. There may be two or more types. By doing so, white light is obtained by mixing the colors of light from different phosphors. In this case, it is preferable that the average particle diameter and the shape of the respective phosphors are similar in order to mix the light emitted from the respective phosphors better and reduce the color unevenness. Further, in consideration of the fact that the nitride-based phosphor absorbs a part of the light whose wavelength is converted by the YAG phosphor, the nitride-based phosphor is arranged at a position closer to the recess side surface than the YAG-based phosphor. It is preferable to form the coating layer so that By configuring in this way,
The color rendering property can be improved as compared with the case where the YAG-based phosphor and the nitride-based phosphor are mixed and contained in the coating layer.

In particular, the phosphor of the present invention is formed so that the average particle diameter thereof is smaller than the minimum value of the distance between the side surfaces of the recesses provided on the surface of the light emitting element. Can store more than one particle.

In the present invention, the particle size of the phosphor is a value obtained by a volume-based particle size distribution curve, and the volume-based particle size distribution curve is a particle size distribution of the phosphor measured by a laser diffraction / scattering method. It can be obtained. Specifically, in an environment of a temperature of 25 ° C. and a humidity of 70%, a phosphor is dispersed in an aqueous solution of sodium hexametaphosphate having a concentration of 0.05%, and a laser diffraction particle size distribution analyzer (SALD-2000A) is used. Particle size range 0.03μ
It was obtained by measuring from m to 700 μm.

In the present embodiment, the particle-like phosphors actually used have different sizes (major axis and minor axis) for each particle even if the particle diameters are made uniform by sieving.
In addition, phosphors may aggregate with each other to form a cluster (cluster) of phosphor particles as shown in FIG. Therefore, in the present specification, the size of the phosphor particles is represented by an average particle size, and the average particle size means, as shown in FIG. 5, the maximum diameter R _max of the aggregate (a) of the phosphor particles, The average value of the maximum diameter (major axis) of the phosphor particles (b) which are in the state of one particle without aggregation and the maximum diameter (major axis) of the phosphor particles (c) smaller than (b) is meant.

FIG. 5D is a schematic sectional view showing the relationship between the particulate fluorescent material 103 and the recess 110 and the island 111 in the present embodiment. Here, it is preferable that the recess 110 has a shape that widens in the opening direction.
Further, it is preferable that the island portion 111 has a shape such that the width thereof becomes narrower toward the outside of the light emitting element. This is because such a shape makes it easier for the particulate phosphor 103 to fall into the recess 110 during the step of forming the coating layer 108. Further, as shown in FIG. 5 (d), the average particle size of the particulate phosphor is not more than the minimum value r _min of the space between the inner walls of the recess (when the opening is regarded as a circle, the inner diameter of the circle). And is larger than the maximum value of the width of the upper surface of the island portion 111. Furthermore, the depth of the recesses is preferably larger than the average particle size. As a result, the particulate phosphor according to the present invention is almost completely accommodated in the recess as shown in FIG. 5 (d), and even if it comes into contact with the upper surface of the island in the step of applying the phosphor, the particulate phosphor remains in the recess. The probability that it will fall and the phosphor will be housed in the recess is further increased. [Spray Device 300] In this embodiment, as shown in FIGS. 6 and 7, a container 301 for containing the coating liquid,
A valve 302 for adjusting the flow rate of the coating liquid, a circulation pump 303 for transporting the coating liquid to the nozzle 201 and then to the container 301, and a nozzle 201 for ejecting the coating liquid in a spiral shape are transport pipes 307 and 308, respectively. , 30
The spray device 300 tied at 9 is used. (Container 301) A stirrer 304 is attached to the container 301 that stores the coating liquid, and the coating liquid is constantly stirred during the coating operation. The coating liquid stored in the container 301 is constantly stirred by the stirrer 304, and the phosphor contained in the coating liquid is always uniformly dispersed in the solution. (Valve 302) The valve 302 adjusts the flow rate of the coating liquid transported from the container 301 through the transport pipe 309 by opening and closing the valve. (Circulation Pump 303) The circulation pump 303 transfers the coating liquid from the container 301 to the valve 302 and the compressor 305.
Via the transfer pipe 307 to the tip of the nozzle 201, and then the coating liquid remaining without being ejected from the nozzle 201 is transferred to the container 301 via the transfer pipe 308. The coating liquid is supplied to the container 3 by the circulation pump 303.
01 through the valve 302 to the tip of the nozzle 201 through the transfer pipe 307, and then the transfer pipe 30.
Since it is conveyed to the container 301 through 8, it is always circulating in the spray device. Therefore, since the coating liquid is agitated or circulated over the entire spray device, the phosphor contained in the coating liquid is always in a uniform dispersed state during the coating operation. (Compressor 305) The compressor 305 is installed in the apparatus by being connected to the carrier pipe 307 or 309, compresses the air carried through the carrier pipe 307, and adjusts the pressure of the coating liquid carried through the carrier pipe 309. To do. The compressed air and the pressure-adjusted coating liquid are respectively conveyed to the nozzle 201 by the compressor 305. Here, the pressure of the compressed air is monitored by the pressure gauge 306.

An operation handle is attached in front of the nozzle, and by adjusting the grip of the handle,
The structure is such that the amount of the coating liquid ejected from the tip of the nozzle can be adjusted.

Using the spray device 300 as described above, the coating liquid is jetted at high speed together with the high-pressure gas to coat the upper surface, side surfaces and corners of the light emitting element. (Nozzle 2
01) In a conventional spray device equipped with a nozzle for ejecting a spray-like coating liquid on a gas flow directed vertically to the upper surface of the light-emitting device, the side surface of the light-emitting device is parallel to the spray direction of the coating liquid, and immediately after the start of coating. The spray composed of the atomized coating liquid passes through the side surface of the light emitting element. In addition, the coating was difficult to be applied on the surface of the light emitting element that is shaded by the conductive wire that supplies power to the light emitting element, and the thickness of the coating layer was different from that on the surface of the light emitting element that is not shaded by the conductive wire. Therefore, if you want to cover the entire surface of the light-emitting element, rotate the light-emitting element or the nozzle to direct the entire surface of the light-emitting element in the ejection direction of the coating liquid, or repeat the coating on the surface of the support on which the light-emitting element is mounted. The side surface of the light emitting device has to be covered with a thick coating layer formed as a result. Therefore, it is not possible to apply the side surface from the corner of the light emitting element with good workability,
The thickness of the coating layer covering the entire surface of the light emitting device was different between the top surface and the side surface of the light emitting element. Further, when the atomized coating liquid is sprayed at a high speed, there is a problem that the conductive wire connecting the pair of positive and negative electrodes of the light emitting element and the external electrode is deformed or broken.

In this embodiment, an apparatus is used in which the coating liquid and gas (air in this embodiment) are ejected in a spiral shape through the nozzle 201. There are several gas outlets around the nozzle of this device.
The ejection direction of the gas ejected from these ejection ports is set at a certain angle with respect to the surface to be coated. Therefore, when gas is simultaneously sent to those gas jets rotating around the jet of the coating liquid, the flow of the entire gas collected from the jets is a spiral flow, It will be a spiral flow or a flow that is the reverse of the air flow in a tornado. In addition, a jet of the coating liquid is provided at the center of the nozzle of this device, and when the coating liquid is jetted at the same time as the jet of gas,
The atomized coating solution diffuses along a spiral flow or a gas flow that is the reverse of the air flow in a tornado.

The diameter of the entire spray diffused in a spiral shape increases from the injection start point above the light emitting element toward the surface of the light emitting element. Further, the rotation speed of the spray made of the coating liquid decreases as it approaches the surface of the light emitting element from the injection start point above the light emitting element. That is, when the atomized coating liquid is ejected from the nozzle and diffused in the air, the spray spreads in a conical shape in the vicinity of the nozzle, which is the injection start point, but the spray spreads in a columnar shape away from the nozzle. Therefore, in this embodiment, it is preferable to adjust the distance from the upper surface of the light emitting element to the lower end of the nozzle so that the surface of the light emitting element comes to the place where the spray spreads in a cylindrical shape. At this time, the spray is
Since it rotates in a spiral shape and its speed is weakened, it can be sufficiently sprayed not only on the entire upper surface of the light emitting element but also on the entire side surface thereof. Thereby, the work can be performed with the light emitting element or the nozzle fixed. In addition, since the spray speed is weakened in a state where the spray spreads in a columnar shape, when the spray is sprayed on the surface of the light emitting element, the phosphor particles contained in the spray may impact the surface of the light emitting element. In addition, the manufacturing yield is improved.

As a result, workability is improved and Si is
The entire surface of the light emitting element, that is, the upper surface of the island portion, the side surface of the recess, and the corner portion of the light emitting element can be covered with the same film thickness by the coating layer in which the phosphor is bound by O ₂ . [Coating Layer 108] The coating layer 108 used in the present invention is a layer containing a phosphor that converts the light emitted from the light emitting element and a resin and / or glass that binds the phosphors together. Particularly in the coating layer formed by using the spray in one embodiment of the present invention, the coating layers provided on the upper surface, the concave portion and the corner of the island portion of the light emitting element have substantially the same thickness. Further, the coating layer is a continuous layer without interruption even at the corners of the surface of the light emitting device.

Due to reflection from the package or the like, high-energy light emitted from the light emitting element has a high density in the coating layer. Further, the phosphor may be reflected and scattered by the phosphor to expose the coating layer to high-density and high-energy light. Therefore, when a nitride-based semiconductor having high emission intensity and capable of emitting high-energy light is used as a light-emitting element, Si, Al, Ga, Ti, Ge, P, which has light resistance to the high-energy light, B, Zr, Y,
It is preferable to use an oxide having one or more of Sn, Pb and alkaline earth metals as a binder or a binder.

SiO ₂ , Al ₂ O ₃ and MSiO ₃ (where M is Zn, Ca, Mg, Ba, Sr, Zr, Y, Sn, and
Pb etc. are mentioned. A transparent inorganic member containing a phosphor is preferably used. The phosphors are bound to each other by these translucent inorganic members, and the phosphors are further deposited and bound on the LED chip or the support. In the present invention, at least Si, Al, Ga, Ti, G
The oxide containing at least one element selected from the group of e, P, B, Zr, Y, Sn, Pb, or an alkaline earth metal is at least Si, Al, Ga, Ti, Ge, P,
It is produced by an organometallic compound containing one or more elements selected from the group of B, Zr, Y, Sn, Pb or alkaline earth metals. Here, specific examples of the organometallic compound include ethyl silicate which is one of alkyl silicates, aluminum alcoholate, and aluminum isopropoxide and aluminum ethoxide which are one of aluminum alkoxides.
If an organometallic compound that is liquid at room temperature is used among such organometallic compounds, by adding an organic solvent,
The workability can be improved because it is possible to easily adjust the viscosity in consideration of workability and prevent the formation of a solidified product such as an organometallic compound. In addition, since such an organometallic compound easily causes a chemical reaction such as hydrolysis, at least Si, Al, Ga, Ti, Ge, P, B, Zr, Y,
It is possible to form a coating layer in which the phosphor is bound by an oxide containing one or more elements selected from the group of Sn, Pb or alkaline earth metals. Therefore, the method using an organometallic compound is 350 ° C.
LE under the above high temperature or static electricity
Unlike other methods of forming a coating layer on D,
Without deteriorating the performance as a light emitting element of LED,
By baking at about 150 ° C., a coating layer or the like containing an amorphous inorganic substance can be easily formed on the LED chip, and the manufacturing yield is improved.

[0073]

EXAMPLES Examples of the present invention will be described in detail below. The present invention is not limited to the examples shown below. (Embodiment 1) FIG. 1 is a schematic sectional view showing a structural example of a light emitting device containing a gallium nitride-based compound semiconductor in this embodiment. Hereinafter, a method for forming the light emitting device in this embodiment will be described.

On the sapphire substrate 107, a GaN buffer layer (not shown), an n-type GaN layer 106, a light emitting layer 105,
Then, the p-type GaN layer 104 is sequentially crystal-grown. Next, the positive electrode 109 and the p-type GaN layer 104 formed on the p-type GaN layer 104 are patterned by the PEP method and then etched by the RIE method to expose the n-type GaN layer 106. Then, patterning is performed using the PEP method, and Ti / Au or the like is used as the n-side electrode to form the n-type GaN layer 106.
It is vapor-deposited on the surface and formed by lift-off. As the p-side electrode, after patterning by the PEP method, Ni layer (thickness 5.0 nm) / Au layer (thickness 20 n) was formed by the vacuum deposition method.
m) is formed on the p-type GaN layer as a current diffusion electrode having a thickness of 1 μm. Further, in this embodiment, the p-side electrode is a p-type Ga.
After the N layer is formed on the entire surface, the p-side electrode and a part of the p-type GaN layer are removed by etching from above to form a continuous recess from the surface of the p-side electrode to the p-type GaN. 102 is formed. In the present embodiment, the space between the inner walls 101 of the recess is such that the opening of the recess is
A plurality of circular recesses having a size of 10 μm are provided, and the average particle size of the phosphor is 5.0 μm. The depth of the recess is 1.
0 μm.

Next, the phosphor is added to a solution containing ethyl silicate as the organometallic compound and ethylene glycol as the organic solvent as described above, and the coating solution contained in the state where the phosphor is uniformly dispersed is applied to the light emitting device. After dropping (potting) from above the concave portion of the p-type layer, the particulate phosphor having a specific gravity larger than that of the coating liquid is naturally dried while settling. After that, the phosphors are bound to each other by an amorphous inorganic substance generated by firing at about 150 ° C., and the phosphors are bound to the inner wall surface of the recess.

According to the present embodiment, there is a high possibility that one or more particles of the particulate fluorescent substance will exist in the concave portion, and the light emitted from the light emitting layer causes the particulate fluorescent substance in contact with the inner wall and the bottom portion of the concave portion. As a result, the light is immediately converted into visible light before being attenuated due to propagation, so that the conversion efficiency into visible light is high and a sufficient level of visible light can be obtained efficiently. (Embodiment 2) FIG. 2 is a sectional view showing a structural example of a light emitting device containing a gallium nitride compound semiconductor in this embodiment.

A light emitting device having a cross section as shown in FIG. 2 is formed by the same method as in the first embodiment. here,
The side surface of the concave portion has a mesa shape with an inclination angle of 45 degrees, and the concave portion having a shape (mortar shape) that widens in the opening direction of the concave portion is provided. Otherwise, the coating layer 108 is formed in the same manner as in Example 1, and the phosphor is bound to the surface of the p-type layer and the inner wall of the recess.

According to this embodiment, the probability that one or more particles of the particulate fluorescent substance exist in the concave portion is further increased. further,
Light emitted from the light-emitting layer and traveling toward the side wall of the recess is at the interface between the side wall of the recess and the coating layer (side surface of the recess).
Then, since the fluorescent substance that is accommodated inside the concave portion is refracted and the wavelength of the fluorescent substance that is in contact with the inner wall of the concave portion is sufficiently converted, the wavelength conversion efficiency of the fluorescent substance is increased. (Embodiment 3) In this embodiment, in a light emitting device having a cross section as shown in FIGS. 1, 2 and 4, the minimum value of the interval between the recess inner wall 101 and the recess inner wall adjacent to the recess is To be smaller than the average particle size of the particulate phosphor,
That is, the maximum width of the upper surface of the island portion 111 is set to be smaller than the average particle diameter of the particulate phosphor. Specifically, the minimum value of the interval between the recess inner wall 101 and the recess inner wall adjacent to the recess is 1.0 μm, and the average particle diameter is 5.0 μm. And
As in Example 1, except that the concave portion was formed on the surface of the p-type layer, p
A phosphor is bound to the surface of the mold layer and the inner wall of the recess.

By doing so, the particulate fluorescent substance is likely to fall into the concave portion in the coating step, thereby increasing the probability of accommodating the particulate fluorescent substance in the concave portion, and There is one or more particles of particulate phosphor, and the conversion efficiency of visible light by the phosphor is higher,
It is possible to efficiently obtain a sufficient level of visible light. Example 4 As shown in FIG. 1, a positive electrode having a thickness of 1.0 μm was formed on a p-type layer and then etched by RIE to continuously form recesses from the positive electrode to the p-type layer. Is formed, and a light emitting element having a positive electrode is formed on the upper surface of the p-type layer between the recess and the recess adjacent to the recess. After that, a phosphor is bound to the surface of the p-type layer and the inner wall of the recess as in the other examples.

By doing so, it is possible to reduce the amount of the particulate phosphor existing on the positive electrode, which is difficult to transmit the light emitted from the light emitting layer, and increase the amount of the phosphor existing in the recess. . Therefore, the conversion efficiency of the fluorescent substance into visible light becomes higher, and a sufficient level of visible light can be efficiently obtained. (Example 5) A phosphor is bonded to the inner wall of the recess and the surface of the light emitting element in the same manner as in Example 1 except that the recess is formed in the negative electrode and the n-type layer of the light emitting element from which the sapphire substrate is removed. Here, the n-type layer is provided with a plurality of circular recesses such that the distance between the side surfaces of the recesses is 10 μm at the recess opening, and the average particle diameter of the phosphor is 5.0 μm. The depth of the recess is 5.0 μm.

In this way, the light emitted from the light-emitting layer is immediately converted into visible light by the particulate phosphor that is in contact with the side wall and the bottom of the recess, so that the conversion efficiency to visible light is high and a sufficient level is obtained. The visible light can be efficiently obtained. (Embodiment 6) FIG. 7 shows a spray device 300 used for forming the coating layer 108 in this embodiment. As shown in FIG. 6, in a state where the light emitting element is heated, a spraying device 300 sprays a coating solution containing a phosphor from above the light emitting element in a mist and while rotating spirally to coat the coating solution. A phosphor is bonded to the surface of the p-type layer and the inner wall of the recess as in Example 1, except that the method of molding the layer by firing is used. By using such a spray device 300, it is possible to form the coating layer 108 in the state of the semiconductor wafer and then cut into chips. By forming the coating layer 108 in the state of the semiconductor wafer which is in the process of forming the LED chip, the intensity of light wavelength-converted by the applied phosphor can be measured in the state of the semiconductor wafer. Therefore, it is possible to easily select chips in a wafer state, and it is possible to improve the mass productivity and the manufacturing yield of semiconductor light emitting devices.

The light emitting device formed in this embodiment is
Since the particulate phosphor is surely present even at the corner where the side surface of the recess and the upper surface of the p-type layer intersect, the conversion efficiency of the phosphor into visible light becomes higher, and a sufficient level of visible light can be obtained. You can get well. Example 7 First, C was formed on the light emitting device by Al ₂ O _3.
CA-Blue _{(Formula, Ca 10 (PO 4) 6} ClB
r, activator Mn, Eu) A coating layer is formed by binding phosphors, and a yttrium-aluminum-garnet-based phosphor (YAG) is formed on the coating layer by SiO _2.
A coating layer in which was bound was formed by the same method as in Example 6.

When the coating layer 108 is composed of a plurality of coating layers as in the present embodiment, the light emitted from the light emitting layer is immediately converted into blue light by the particulate fluorescent material CCA-Blue in the recess, and further by YAG. Since the wavelength is converted, the conversion efficiency is high and a sufficient level of white light can be efficiently obtained.

Further, the refractive index (about 1.4) of the coating layer in which the phosphor is bound by SiO ₂ is Al ₂
Refractive index of the coating layer in which the phosphor by O ₃ is bound (about 1.7) than smaller refraction Al ₂ O ₃ by the refractive index of the coating layer where the fluorescent substance is bound gallium nitride-based compound semiconductor layer Since it is smaller than the ratio (about 2.5), the efficiency of extracting light from the light emitting element is increased, the output can be improved, and the heat dissipation is also improved.

[0085]

EFFECT OF THE INVENTION The generated short-wavelength light (ultraviolet light) can be efficiently converted into visible light or the like by a phosphor and can be efficiently extracted to the outside, and the material for binding the phosphor is a short-wavelength light. It is not deteriorated by light (ultraviolet light) or high-power light. Therefore, the light emitting device according to the present invention can improve the light extraction efficiency and can be a highly reliable light emitting device.

[0086]

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a light emitting device according to a first embodiment of the invention.

FIG. 2 is a schematic cross-sectional view of a light emitting device according to a second embodiment of the invention.

FIG. 3 is a schematic top view of a light emitting device according to an embodiment of the invention.

FIG. 4 is a schematic cross-sectional view of a light emitting device according to an embodiment of the invention.

FIG. 5 is a schematic sectional view of phosphor particles according to an example of the present invention.

FIG. 6 is a schematic view showing an example of a step of applying a phosphor to a light emitting element in the step of forming a light emitting device according to the present invention.

FIG. 7 is a schematic view showing an example of an apparatus for applying a phosphor to a light emitting element in a process of forming a light emitting apparatus according to the present invention.

[Explanation of symbols]

100 ... Light emitting device 101 ... Recess inner wall 102, 111 ... Island 103 ... Particulate phosphor 104 ... p-type layer 105 ... Light-emitting layer 106 ... N-type layer 107 ... Sapphire substrate 108 ... Coating layer 109 ... Positive electrode 110 ... Recess 112 ... Negative electrode 201 ... Nozzle 202, 408, 409 ... Phosphor 203 ... Ethyl silicate 204 ... Support 205 ... Heater 300 ... Spray device 301 ... container 302 ... Valve 303 ... Circulation pump 304 ... Stirrer 305 ... Compressor 306 ... Pressure gauge 307, 308, 309 ... Transport pipe

Claims (8)

[Claims] 1. A light emitting element having at least an n-type layer having a negative electrode and a p-type layer having a positive electrode, and emitting light having different wavelengths by absorbing at least a part of light from the light emitting element. In the light emitting device having the particulate phosphor, the light emitting device has a recess (110) on the surface of the light emitting device, and the particulate phosphor is provided in the recess. 2. The light emitting device according to claim 1, wherein the recess (110) has a mesa-shaped side surface. 3. The light emitting device according to claim 1, wherein the concave portion (110) is provided continuously with at least the p-type layer and the positive electrode. 4. The light emitting device according to claim 1, wherein the concave portion (110) is provided continuously at least in the n-type layer and the negative electrode. 5. A method of manufacturing a light emitting device having a concave portion (110) on its surface and a particulate phosphor in the concave portion, wherein the minimum value of the distance between the inner walls of the concave portion (101) is the particle. A first step of forming a recess (110) larger than the average particle diameter of the particulate phosphor in the light emitting element, a second step of dropping a coating liquid containing the particulate phosphor onto the light emitting element, and the particles A method for manufacturing a light-emitting device, comprising a third step of drying a coating solution in which the fluorescent substance is settled. 6. A method for manufacturing a light emitting device having a concave portion (110) on the surface and a particulate phosphor in the concave portion, wherein the minimum value of the distance between the inner walls (101) of the concave portion is the particle. Step of forming a concave portion (110) larger than the average particle size of the phosphor in the light emitting element, and a coating liquid containing the phosphor from above the light emitting element in a state where the light emitting element is heated. A method for manufacturing a light-emitting device, comprising: a second step of spraying while rotating in a mist and spiral shape; and a third step of drying the coating liquid. 7. The method for manufacturing a light emitting device according to claim 5, wherein in the first step, the recesses are formed at intervals smaller than the average particle diameter of the particulate phosphor. 8. The coating liquid is at least Si, Al,
A solution containing an organic metal compound containing one or more elements selected from the group of Ga, Ti, Ge, P, B, Zr, Y, Sn, Pb, or an alkaline earth metal, an organic solvent, and a phosphor. The method for manufacturing a light emitting device according to claim 5, wherein