JP2003224307A - Light-emitting diode and its formation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a light-emitting diode having a granular phosphor to emit light by the conversion of an emission from an LED chip and reducing color-tone unevenness in all directions, and its formation method. <P>SOLUTION: The light-emitting diode has the LED chip arranged on a supporter and the granular phosphor absorbing at least a part of an emission from the LED chip and being emitting light by the conversion of a wavelength. In the light-emitting diode, the thickness of a coating section having the granular phosphor arranged on the LED chip and the thickness of the coating section having the granular phosphor disposed on the supporter excepting the LED chip are approximately equal particularly. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

The present invention relates to an LED display,
Related to a light emitting device used for a backlight light source, a traffic light, an illuminated switch, various sensors, various indicators, and the like, in particular, in a light emitting diode having a phosphor capable of wavelength-converting light emitted from a light emitting element, a light emitting direction, The present invention relates to a light emitting diode having improved color tone unevenness and mass productivity and a method for forming the same.

[0002]

2. Description of the Related Art A light emitting diode (hereinafter referred to as L
Also called ED. ) Is small, efficient and emits bright colors. In addition, since it is a semiconductor element, there is no fear of breaking the ball. It has excellent driving characteristics and is resistant to vibration and repeated ON / OFF lighting. Therefore, it is used as various indicators and various light sources. However, since the LED has an excellent monochromatic peak wavelength, it cannot emit light having an emission wavelength such as white.

Therefore, the applicant of the present invention discloses, as a light emitting diode capable of emitting light of other colors by color-converting the light emitted from the blue light emitting diode by means of a blue light emitting diode and a fluorescent substance, JP-A-5-152609 and JP-A-5-152609. 7-993
The light emitting diode described in Japanese Patent No. 45, etc. has been developed. With these light emitting diodes, one type of LED
The chip can be used to emit other emission colors such as white and green using a blue LED chip.

Specifically, an LED chip capable of emitting blue light is arranged on a cup or the like provided at the tip of the lead frame. The LED chip is electrically connected to a metal stem or a metal post provided with the LED chip. Then, a fluorescent material that absorbs light from the LED chip and converts the wavelength is contained in a resin mold member that covers the LED chip. By selecting a blue light emitting diode and a fluorescent substance that absorbs the emitted light and emits yellow light, white light can be emitted by utilizing the color mixture. It can be used as a white light emitting diode that emits light with sufficient brightness.

[0005]

However, this light emitting diode tends not to be formed in a desired color.
When light emitting diodes are mass-produced, it is difficult to form each light emitting diode in a desired chromaticity range, and the yield tends to decrease. Further, there is a problem that color unevenness occurs slightly on the light emission observation surface of the light emitting diode.

Specifically, when viewed from the light emission observation surface side, the central portion where the LED chip, which is a light emitting element, is arranged has a blue color.
There may be yellow, green, or red-colored portions in a ring shape in the peripheral direction. Human color perception is particularly sensitive in white. Therefore, even if there is a slight color difference, it looks reddish white,
I feel greenish white, yellowish white, etc.

The color unevenness caused by directly looking at such a light emission observation surface is not only unfavorable in terms of quality, but also causes color unevenness on the display surface when used in a display device and an error in precision equipment such as an optical sensor. It also becomes. Further, as a more severe condition, the brightness of the light emitting diode tends to decrease when used for a long time with high brightness. An object of the present invention is to solve the above-mentioned problems and to form a light emitting diode which is excellent in mass productivity because color unevenness on an emission observation surface and variations among the light emitting diodes are extremely small.

[0008]

The present invention has an LED chip arranged on a support, and a particulate phosphor that absorbs at least a part of the light emitted from the LED chip and converts the wavelength to emit light. It is a light emitting diode. In particular, in the present invention, the thickness of the coating portion having the particulate phosphor disposed on the LED chip and the thickness of the coating portion having the particulate phosphor disposed on the support other than the LED chip are The light emitting diodes are substantially equal.

Further, in the light emitting diode of the present invention according to claim 2, the coating portion together with the particulate phosphor is at least one of Si, Al, Ga, Ti, Ge, P, B and one or two of alkaline earth elements. It is a light emitting diode made of an oxide having one or more species.

The light emitting diode of the present invention according to claim 3 is a yttrium-aluminum-garnet-based phosphor in which the light-emitting layer of the LED chip is a nitride-based compound semiconductor and the particulate phosphor is activated by cerium. Is.

In the light emitting diode of the present invention according to claim 4, the main emission peak of the LED chip is 400 nm to 53 nm.
0 nm and the main emission wavelength of the particulate phosphor is an LED
It is a light emitting diode that is longer than the main emission peak of the chip.

In the light emitting diode of the present invention according to claim 5, the light emitting layer of the LED chip is a nitride compound semiconductor, and the particulate phosphor is (Re1-xSmx) 3 (Al1-yG).
ay) 5O12: Ce. (However, 0 ≦ x <1, 0 ≦
y ≦ 1 and Re are at least one element selected from Y, Gd, and La. According to a sixth aspect of the present invention, there is provided a method for forming a light emitting diode, which includes an LED chip and a phosphor that absorbs at least a part of light emitted from the LED chip and converts the wavelength to emit light. In particular,
This is a method for forming a light emitting diode in which a coating portion containing a particulate phosphor is formed on an LED chip by sedimentation of a particulate phosphor dispersed in a gas phase or a liquid phase.

[0013]

In the present invention, the thickness of the coating portion containing the particulate phosphor is substantially equal both on the LED chip and on the substrate on which the LED chip is arranged. It is possible to obtain uniform emission characteristics in which the differences in the optical path lengths of the light emitted from the LED chips are relatively equal. Further, it is possible to extremely reduce color unevenness on the light emitting surface and variations among the light emitting diodes. Further, by depositing and depositing the particulate phosphor on the package in which a plurality of LED chips are arranged, a large number of light emitting diodes can be formed at one time with good mass productivity. Even if the amount of the particulate phosphor disposed on the LED is extremely small, the amount of the particulate phosphor (thickness of the coating portion) can be controlled uniformly.
Therefore, a light emitting diode with less variation can be formed.

The coating portion is Si, Al, Ga, T
The particulate phosphor is bound with an inorganic substance that is an oxide having one or more of i, Ge, P, B, and an alkaline earth element. As a result, even if a relatively high energy light from the LED chip is irradiated at a high density, the coating portion will not be colored and deteriorated. Therefore, it is possible to obtain a light emitting diode in which the brightness does not decrease even if the light is emitted with high brightness for a long time.

[0015]

DETAILED DESCRIPTION OF THE INVENTION As a result of various experiments, the present inventor
Distributing the particle-shaped phosphors on the ED chip and the particle-shaped phosphors arranged on a support other than the ED chip substantially evenly improves the unevenness of color tone on the light emission observation surface and the variation among the light emitting devices. The inventors have found out what can be done and have completed the present invention.

It is considered that the unevenness of the color tone on the light emission observation surface and the variation among the light emitting diodes are caused by the inclination of the planar distribution of the particulate phosphor contained in the coating portion when the coating portion is formed. That is, the coating portion can be placed on a desired cup by discharging the resin containing the particulate phosphor from a tube such as a thin nozzle.

However, it is extremely difficult to apply an equal amount of the particulate phosphor contained in the binder onto the LED chip at a high speed. In addition, the shape of the finally formed coating portion is not constant due to the viscosity of the binder and the surface tension between the coating surface and the package surface in contact with the coating portion. Coating thickness (amount of particulate phosphor)
Is partially different, and the amount of light from the LED chip and the amount of light from the particulate phosphor are partially different.

Therefore, L is partially present on the emission observation surface.
The color of light emitted from the ED chip becomes strong, and the color of light emitted from the phosphor becomes strong, resulting in uneven color tone. In addition, it is considered that variations occur among the light emitting diodes. In the present invention, the unevenness of color tone and the directivity can be improved by uniformly disposing the particulate phosphors formed on the LED chip and other parts. Hereinafter, the constituent members of the present invention will be described in detail.

(Coating parts 111, 112) The coating parts 111, 112 used in the present invention are provided in a cup of a mount lead or in an opening part of a package separately from the molding member, and are formed in the LED chip 103. Examples thereof include a particulate fluorescent substance that converts light emission and a resin or glass that binds the particulate fluorescent substance. In the coating portions 111 and 112 of the present invention, the thickness of the coating portion 111 provided on the LED chip 103 and the thickness of the coating portion 112 provided on the support other than the LED chip are substantially equal. The thickness of the coating part 111 provided on the LED chip 103 and the coating part 112 provided on the surface of the opening of the package serving as the support is such that the particulate phosphor dispersed in the gas phase or the liquid phase is kept static. By placing them and allowing them to settle, they can be relatively easily formed to be substantially equal.

In the coating section, L
High-energy light emitted from the ED chip is also reflected, resulting in high density. Further, the particulate fluorescent material may be reflected and scattered, and the coating portion may be exposed to high-density, high-energy light. Therefore, a nitride-based semiconductor that emits high-energy light with high emission intensity is used as an LED.
When used as a chip, Si, Al, Ga, Ti, Ge, which have light resistance to those high energy lights,
It is preferable to use an oxide containing one or more of P, B and alkaline earth metals as a binder.

As one of the specific main materials of the coating portion, a translucent inorganic member such as SiO2, Al2O3, MSiO3 (where M is Zn, Ca, Mg, Ba, Sr, etc.). Those containing a particulate fluorescent substance are preferably used. A particulate fluorescent substance is bound by these translucent inorganic members and deposited in layers on the LED chip and the support. The coating part may contain an ultraviolet absorber together with the particulate phosphor.

The coating parts 111, 121
The particles of the coating material 111 and 121 are thoroughly mixed with the binder and sprayed from the nozzle of the discharge means 201 into the container 202. In the container 202,
A package 105 having an LED chip is arranged. The material ejected from the nozzle is suspended in the container 2
It collects in 02. When the container 202 is left standing, the phosphor particles settle and the phosphor film 204 is formed on the bottom of the container 202. After discharging the supernatant, warm air discharged from the drying device 205 is blown to dry. After that, each package 105 is taken out to obtain a light emitting diode having a particulate phosphor.

(Particulate Phosphor) The phosphor used in the present invention means a particulate phosphor that emits light when excited by light emitted from at least the semiconductor light emitting layer of the LED chip 103. When the light emitted by the LED chip 103 and the light emitted by the particulate phosphor have a complementary color relationship or the like, white light can be emitted by mixing the respective lights. Specifically, when the light from the LED chip 103 and the light of the particulate phosphor that is excited and emitted by the LED chip 103 respectively correspond to the three primary colors of light (red, green, and blue), The emitted blue light and the yellow light of the particulate fluorescent material that is excited by the emitted blue light and emits light.

The emission color of the light emitting diode is determined by the ratio of the particulate fluorescent material to various resins that act as a binder for the particulate fluorescent material or an inorganic member such as glass, the sedimentation time of the particulate fluorescent material,
Various adjustment of the shape of the particulate phosphor and the LED
By selecting the emission wavelength of the 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 diode.

Specific particulate phosphors include cadmium zinc sulfide activated by copper and yttrium-aluminum-garnet-based phosphor activated by cerium. In particular, when using for a long time with high brightness (Re
1-xSmx) 3 (Al1-yGay) 5O12: Ce (0≤x <
1, 0 ≦ y ≦ 1, provided that Re is at least one element selected from the group consisting of Y, Gd, and La. ) And the like are preferable. Especially as a particulate phosphor (Re1-xSm
x) 3 (Al1-yGay) 5O12: Ce is used,
A light emitting diode which is arranged in contact with or close to an LED chip and has sufficient light resistance with high efficiency even when the irradiance is (Ee) = 3 W · cm −2 or more and 10 W · cm −2 or less can be obtained.

(Re1-xSmx) 3 (Al1-yGay) 5O1
Since the 2: Ce phosphor has a garnet structure, it is resistant to heat, light and moisture, and the peak of the excitation spectrum can be set to around 470 nm. Also, the emission peak is 530
It can have a broad emission spectrum in the vicinity of nm and skirting down to 720 nm. Moreover, the composition A
By substituting a part of l with Ga, the emission wavelength shifts to a short wavelength, and by substituting a part of Y of the composition with Gd,
The emission wavelength shifts to longer wavelengths. By changing the composition in this way, it is possible to continuously adjust the emission color. Therefore, the ideal condition for converting the blue-based light emission of the nitride semiconductor into the white-based light emission is provided such that the intensity on the long wavelength side is continuously changed by the composition ratio of Gd.

Such phosphors include Y, Gd, Ce and S.
An oxide or a compound that easily becomes an oxide at high temperature is used as a raw material for m, Al, La and Ga, and they are sufficiently mixed in a stoichiometric ratio to obtain a raw material. Or Y, Gd, C
e, a coprecipitated oxide obtained by firing a solution obtained by coprecipitating a solution of rare earth elements of Sm in an acid at a stoichiometric ratio with oxalic acid, aluminum oxide, and gallium oxide to prepare a mixed raw material. obtain. An appropriate amount of a fluoride such as ammonium fluoride is mixed as a flux into the crucible and packed in a crucible.
Firing is performed in the temperature range of 50 to 1450 ° C for 2 to 5 hours to obtain a fired product. Next, the fired product is ball-milled in water, washed, separated, dried, and finally passed through a sieve to obtain a desired particulate phosphor.

In the light emitting diode of the present invention, the particulate phosphor may be a mixture of two or more kinds of particulate phosphors. That is, two or more kinds of (Re1-xSmx) 3 (Al1-yG) having different contents of Al, Ga, Y, La, Gd and Sm.
ay) It is possible to increase the wavelength components of RGB by mixing the 5O12: Ce phosphor. In addition, at present, there are variations in the emission wavelength of the semiconductor light emitting device, so that it is possible to obtain a desired white light by mixing and adjusting two or more kinds of phosphors. Specifically, by adjusting and containing the amount of phosphors having different chromaticity points according to the emission wavelength of the light emitting element, light is emitted at any point on the chromaticity diagram connected between the phosphors and the light emitting element. be able to.

Such a particulate phosphor can be dispersed in a gas phase or a liquid phase and uniformly emitted. The particulate fluorescent material in the gas phase or liquid phase settles due to its own weight. In particular, by allowing the suspension to stand in the liquid phase, it is possible to form a layer having a more uniform particulate phosphor. It is possible to form a desired amount of the particulate phosphor by repeating a plurality of times as desired.

(LED Chip 103) The LED chip 103 used in the present invention is capable of exciting the particulate fluorescent material. The LED chip 103, which is a light emitting element, is M
GaAs, InP, GaA on the substrate by OCVD etc.
lAs, InGaAlP, InN, AlN, GaN, I
A semiconductor such as nGaN, AlGaN, or InGaAlN is formed as a light emitting layer. The semiconductor structure is MIS.
A homo structure, a hetero structure, or a double hetero structure having a junction, a PIN junction, a PN junction, or the like can be used. 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 IniGajAlk) capable of efficiently emitting a relatively short wavelength that can efficiently excite the particulate phosphor.
N, where 0 ≦ i, 0 ≦ 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 SiO2 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 removing SiO2 by etching 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 introducing the P-type dopant, 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 layer structure of a specific light emitting element, an N-type contact layer which is a gallium nitride semiconductor, an aluminum nitride / gallium semiconductor is formed on a sapphire substrate or a silicon carbide having a buffer layer in which gallium nitride, aluminum nitride, etc. are formed at a low temperature. An N-type clad layer, an active layer made of Zn and Si doped indium gallium nitride semiconductor, a P-type clad layer made of aluminum nitride / gallium semiconductor, and a P-type contact layer made of gallium nitride semiconductor are laminated. Suitable examples include: In order to form the LED chip 103, in the case of the LED chip 103 having a sapphire substrate, P is formed by etching or the like.
After forming the exposed surface of the type semiconductor and the N-type semiconductor, each electrode having a desired shape is formed on the semiconductor layer by a sputtering method, a vacuum evaporation method, or the like. In the case of a 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 the white light is emitted in the light emitting diode of the present invention, the main emission wavelength of the LED chip 103 is 400 nm or more 53 considering the complementary color with the particulate phosphor.
The thickness is preferably 0 nm or less, more preferably 420 nm or more and 490 nm or less. In order to further improve the efficiency of each of the LED chip 103 and the particulate phosphor, 450 nm is required.
More preferably, it is 475 nm or less.

(Package 102) Package 102
Serves as a support for fixing and protecting the LED chip 103 in the recess. Further, it has an external electrode 104 that can be electrically connected to the outside. It is also possible to form the package 102 having a plurality of openings according to the number and size of the LED chips 103. Further, it is preferable that the light emitting observation surface side of the package 102 is colored in a dark color system such that it is colored in a dark color system such as black or gray in order to have a light shielding function.
The package 102 includes coating portions 111 and 112 to further protect the LED chip 103 from an external environment.
In addition to the above, a mold member 106, which is a translucent protective body, can be provided. It is preferable that the package 102 has good adhesion to the coating portions 111 and 112 and the molding member 106 and high rigidity. It is desired to have an insulating property in order to electrically shut off the LED chip 103 and the outside. Further, the package 102 includes the LED chip 1
Mold member 1 when affected by heat from
A material having a small coefficient of thermal expansion is preferable in consideration of the adhesiveness with 06.

The inner surface of the recess of the package 102 may be embossed to increase the adhesion area, or plasma treated to improve the adhesion to the mold member. The package 102 may be formed integrally with the external electrode 104, or the package 102 may be divided into a plurality of pieces and combined by fitting or the like. Such a package 102 can be formed relatively easily by insert molding or the like. Polycarbonate resin, polyphenylene sulfide (P
Resins such as PS), liquid crystal polymer (LCP), ABS resin, epoxy resin, phenol resin, acrylic resin and PBT resin, and ceramics can be used. Also,
Various dyes and pigments are preferably used as the coloring agent for coloring the package 102 in a dark color system. Specifically, C
Preferable examples include r2O3, MnO2, Fe2O3 and carbon black.

The LED chip 103 and the package 102 can be adhered to each other with a thermosetting resin or the like.
Specifically, an epoxy resin, an acrylic resin, an imide resin, or the like can be given. In addition, Ag paste, carbon paste, ITO paste, metal bumps, and the like are preferably used to arrange and fix the LED chip 103 and electrically connect to the external electrodes 104 in the package 102.

(External Electrode 104) The external electrode 104 is an LE in which electric power from the outside of the package 102 is arranged.
It is used for supplying to the D chip 103. Therefore, various types such as those using a conductive pattern provided on the package 102 or a lead frame can be used. Also, the external electrode 104 can be formed in various sizes in consideration of heat dissipation, electrical conductivity, characteristics of the LED chip 103, and the like. The external electrode 104 preferably has good thermal conductivity in order to dispose the LED chips 103 and to dissipate the heat emitted from the LED chips 103 to the outside. External electrode 104
The specific electrical resistance is preferably 300 μΩ · cm or less, and more preferably 3 μΩ · cm or less. Moreover, the specific thermal conductivity is 0.01 cal / (s) (cm
2) (° C / cm) or higher, more preferably 0.5
cal / (s) (cm2) (° C / cm) or more.

As such an external electrode 104, a copper or phosphor bronze plate whose surface is plated with a metal such as silver, palladium or gold or a solder plating is preferably used. When a lead frame is used as the external electrode 104, it can be used in various ways depending on electrical conductivity and thermal conductivity, but a plate thickness of 0.1 mm to 2 mm is preferable from the viewpoint of workability. A copper foil or a tungsten layer can be formed as the external electrode 104 provided on a support such as a glass epoxy resin or ceramic. When a metal foil is used on the printed circuit board, the thickness of the copper foil is 18 to 7
It is preferably 0 μm. Also, gold on copper foil,
You may give solder plating.

(Conductive Wire 105) The conductive wire 105 is required to have good ohmic contact with the electrodes of the LED chip 103, mechanical connectivity, electrical conductivity and thermal conductivity. The thermal conductivity is 0.01 cal /
It is preferably (s) (cm2) (° C / cm) or more, more preferably 0.5 cal / (s) (cm2) (° C / cm) or more.
Further, in consideration of workability and the like, the diameter of the conductive wire 105 is preferably Φ10 μm or more and Φ45 μm or less. Specific examples of such a conductive wire 105 include a conductive wire using a metal such as gold, copper, platinum, aluminum, or an alloy thereof. Such conductive wires 105 can easily connect the electrodes of each LED chip 103 to the inner leads, mount leads and the like by a wire bonding device.

(Mold Member 106) Mold Member 10
6 can be provided to protect the LED chip 103, the conductive wire 105, the coating portions 111 and 112 containing the particulate fluorescent material, and the like from the outside according to the intended use of the light emitting diode. Mold member 106
Can be formed using various resins or glass. As a specific material for the molding member 106, a transparent resin having excellent weather resistance such as an epoxy resin, a urea resin, a silicone resin, or glass is preferably used.
Further, by including a diffusing agent in the mold member, it is possible to reduce the directivity from the LED chip 103 and increase the viewing angle. Such a mold member 106
May be the same as or different from the binder of the coating portion. Examples of the present invention will be described below, but it goes without saying that the present invention is not limited to specific examples.

[0042]

Example 1 An In0.2Ga0.8N semiconductor having a main emission peak of 460 nm was used as an LED chip. L
The ED chip is TMG on the cleaned sapphire substrate.
A (trimethylgallium) gas, a TMI (trimethylindium) gas, a nitrogen gas and a dopant gas were caused to flow together with a carrier gas to form a gallium nitride-based compound semiconductor by MOCVD. By switching between SiH4 and Cp2Mg as a dopant gas, a gallium nitride-based semiconductor having N-type conductivity and P
A gallium nitride based semiconductor having type conductivity is formed to form a PN junction. As a semiconductor light emitting element, a contact layer which is a gallium nitride semiconductor having N-type conductivity, a clad layer which is a gallium aluminum nitride semiconductor having P-type conductivity, and a contact layer which is a gallium nitride semiconductor having P-type conductivity are formed. Let An active layer of non-doped InGaN having a single quantum well structure and having a thickness of about 3 nm was formed between the contact layer having N-type conductivity and the clad layer having P-type conductivity. (Note that a gallium nitride semiconductor is formed on a sapphire substrate at a low temperature to form a buffer layer. A semiconductor having P-type conductivity is annealed at 400 ° C. or higher after film formation.) Sapphire by etching After exposing the surface of each PN semiconductor on the substrate, each electrode was formed by sputtering. After the scribe line was drawn on the semiconductor wafer thus produced, it was divided by an external force to form a 350 μm square LED chip as a light emitting element.

On the other hand, a chip type LED package was formed by insert molding using a polycarbonate resin. The inside of the chip type LED package is LE
It has an opening in which the D chip is arranged. A silver-plated copper plate is arranged as an external electrode in the package. The LED chip is fixed inside the package using epoxy resin or the like. LE is a conductive wire
Each electrode of the D chip and each external electrode provided on the package are wire-bonded and electrically connected. In this way, 8280 packages in which the LED chips were arranged were formed. A resist film is formed on the surface of each package except the opening. A package with 8280 LED chips is placed in a container with pure electrolyte.

On the other hand, for the particulate phosphor, a solution in which rare earth elements of Y, Gd and Ce were dissolved in an acid at a stoichiometric ratio was coprecipitated with oxalic acid. The coprecipitated oxide obtained by firing this is mixed with aluminum oxide to obtain a mixed raw material. Ammonium fluoride was mixed with this as a flux, packed in a crucible, and baked in air at a temperature of 1400 ° C for 3 hours to obtain a baked product. Ball-mill the baked product in water to wash, separate,
It was dried and finally screened. Formed (Y0.
8Gd0.2) 3Al5O12: Ce phosphor is dispersed in SiO2 sol.

Next, after adjusting the pH to 5.0 with acetic acid,
Immediately put (Y0.8Gd0.
2) 3Al5O12: Ce phosphor and SiO2 sol are suspended and injected all at once (FIG. 2 (A)). After standing (Y0.8Gd0.2) 3Al
The 5O12: Ce phosphor settles and settles on the package (FIG. 2 (B)). The waste liquid in the container is removed, and the package in which the particulate phosphor is deposited on the LED chip is dried with air heated to 120 degrees (FIG. 2 (C)). After that, each light-emitting diode is taken out of the container, and the particulate phosphor adhering to the non-light-emitting portion of the light-emitting diode is removed together with the resist mask, so that the film thicknesses on the LED chip and the package bottom surface are both approximately equal to about 40 μm. Parts can be formed. Further, a translucent epoxy resin was formed as a mold member in the package opening formed with the coating for the purpose of protecting the LED chip and the particulate phosphor from external stress, moisture and dust. After the translucent epoxy resin was mixed in, it was cured at 150 ° C. for 5 hours.
Thus, a light emitting diode as a light emitting device as shown in FIG. 1 was formed.

White light can be emitted by supplying power to the obtained light emitting diode. The color temperature and the color rendering properties were measured from the front of the light emitting diode. Color temperature 8090K, Ra (color rendering index) = 87.5
showed that. Moreover, the light emission rate was 10.8 lm / w. Furthermore, x, y = (0.305, on the CIE chromaticity diagram,
0.315) Within the range surrounded by ± 0.03, about 811
The four light emitting diodes were distributed, and the yield was about 98%.

(Comparative Example 1) In epoxy resin (Y0.8G
d0.2) A light emitting diode was formed in the same manner as in Example 1 except that the phosphor of 3Al5O12: Ce was mixed and projected from the nozzle to form the coating portion. In the cross section of the formed light emitting diode, the end face of the coating portion was raised and the amount of the particulate phosphor was non-uniform. The chromaticity point of the light emitting diode thus formed was measured in the same manner as in Example 1. The chromaticity point of the formed light emitting diode was located approximately on the line connecting the main emission peak of the LED chip and the main emission wavelength of the phosphor, but the yield was about 6
It was only 1%.

[0048]

EFFECTS OF THE INVENTION By using the light emitting diode of the present invention having a uniform coating thickness, it is possible to obtain a light emitting diode in which the deviation of chromaticity due to each direction is extremely small and there is no color deviation when viewed from the light emission observation surface. Further, a light emitting diode with high yield can be obtained.

In particular, with the structure according to claim 1 of the present invention, color shift occurs even at high brightness and long time use,
It is possible to obtain a light emitting diode in which the reduction of the luminous efficiency is extremely small.

With the structure according to the second aspect of the present invention, a light emitting diode having higher light resistance and higher luminous efficiency can be obtained.

With the structure according to claim 3 of the present invention, it is possible to obtain a light emitting diode capable of emitting white light with high brightness and less deterioration in brightness and color shift even when used for a long time.

With the structure according to the fourth aspect of the present invention, a light emitting diode capable of emitting white light and having higher light emission efficiency can be obtained.

With the structure according to claim 5 of the present invention, it is possible to obtain a light emitting diode capable of emitting white light with high brightness and less deterioration in brightness and color shift even when used for a long time.

By adopting the method of claim 6 of the present invention, it is possible to form a light emitting diode which has no light emission unevenness and is capable of uniformly emitting a large amount of light with a high yield.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a chip type LED which is a light emitting device of the present invention.

FIG. 2 is a schematic view showing a forming apparatus for forming the light emitting diode of the present invention.

[Explanation of symbols]

111 ... Coating portion 112 on LED chip ... Coating portion 102 on support 102 ... Package 103 ... LED chip 104 ... External electrode 105 ... Conductive wire 106 ... Mold member 201 ... Ejection means 202 for ejecting the material of the coating portion ... Container 203 ... Material of the coating portion 204 ejected from the nozzle ... Phosphor film 205 ... Drying device capable of blowing heated air

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C09K 11/80 CPN C09K 11/80 CPN CPP CPP

Claims (6)

[Claims] 1. A light-emitting diode comprising: an LED chip disposed on a support; and a particulate phosphor that absorbs at least a part of light emitted from the LED chip and converts the wavelength to emit light. It is characterized in that the thickness of the coating portion having the particulate fluorescent substance arranged on the LED chip is substantially equal to the thickness of the coating portion having the particulate fluorescent substance arranged on the support other than the LED chip. And a light emitting diode. 2. The coating part is made of an oxide containing at least one kind of Si, Al, Ga, Ti, Ge, P, B and an alkaline earth element together with the particulate phosphor. The light emitting diode described. 3. The light emitting diode according to claim 1, wherein the light emitting layer of the LED chip is a nitride-based compound semiconductor, and the particulate phosphor is a yttrium-aluminum-garnet-based phosphor activated with cerium. . 4. The main emission peak of the LED chip is 400.
4. The light emitting diode according to claim 3, wherein the main emission wavelength of the particulate phosphor is longer than the main emission peak of the LED chip. 5. The light emitting layer of the LED chip is a nitride-based compound semiconductor, and the particulate phosphor is (Re1-xS).
The light emitting diode according to claim 1, which is mx) 3 (Al1-yGay) 5O12: Ce. However, 0 ≦ x <1, 0 ≦ y ≦
1, Re is at least one element selected from Y, Gd, and La. 6. A method for forming a light emitting diode, comprising: an LED chip; and a phosphor that absorbs at least a part of light emitted from the LED chip and converts the wavelength to emit light. A method for forming a light emitting diode, characterized in that a coating portion containing the particulate phosphor is formed on the LED chip by sedimentation of the dispersed particulate phosphor.