JP2004193393A - Compound light emitting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compound light emitting element in which the whole temperature rise is suppressed and chrominance of a chip can be uniformized. <P>SOLUTION: The element has a semiconductor light emitting element 3 where an upper side is made the main light take-out face 2, a sub-mount element 4 mounting the semiconductor light emitting element 3, and a resin 6 which comprises a phosphor converting the emission wavelength of the semiconductor light emitting element 3 into another wavelength, and is applied by covering only an upper face of the semiconductor light emitting element 3 arranged on the sub-mount element 4. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention includes a semiconductor light-emitting device such as a light-emitting diode and a light-emitting laser diode formed of a semiconductor film formed on a light-transmitting substrate, and a fluorescent substance that converts the emission wavelength of the semiconductor light-emitting device to another wavelength. The present invention relates to a composite light-emitting device having a resin portion formed as described above.
[0002]
[Prior art]
The technique of converting the emission wavelength using a fluorescent substance has been widely known for a long time. For example, a fluorescent substance is applied to the inner wall surface of a glass of a neon tube, and an orange light is converted into green light, or a GaAs infrared light emitting light emitting diode, and a fluorescent substance is mixed in a mold resin. Those that convert infrared light into green light are well known. Recently, a white LED lamp that emits white light using a fluorescent substance in a GaN-based compound semiconductor light emitting device (GaN LED device) that emits blue light has been commercialized.
[0003]
As shown in FIG. 2, a conventional GaN-based white composite light-emitting element 70 has a GaN-based blue LED 72 flip-chip mounted on a submount element 71, and a YAG-based phosphor 73 is screened so as to cover it. This is a printed composite light emitting device.
[0004]
In the white composite light emitting device 70, the chromaticity of white is controlled by grinding the phosphor 73 on the top surface of the sapphire substrate of the blue LED 72 and adjusting the thickness (t1). For example, the thickness t1 near the white chromaticity coordinates (0.3, 0.3) is t1 <30 μm. On the other hand, the thickness (t2) of the phosphor on the side surface of the blue LED 72 is larger than the thickness (t1) of the phosphor on the top surface.
[0005]
In addition, as such a light emitting element, for example, there is an element shown in Patent Document 1.
[0006]
[Patent Document 1]
JP-A-2000-208822 (pages 2 to 7, FIG. 1)
[0007]
[Problems to be solved by the invention]
However, since the chromaticity of the chip differs depending on the thickness of the phosphor 73, the outer peripheral portion of the phosphor 73 shown in oblique lines in FIG. 2 has a yellowish color. That is, when viewed from the direction a in FIG. 2B, the blue light-emitting component and the yellow component wavelength-converted by the fluorescent substance are mixed and appear white, but when viewed from the direction b, the fluorescent substance layer becomes thicker, so that the yellow color becomes yellow. It looks bitter. Therefore, the chromaticity as a whole shifts in the yellow-green direction, and in order to correct this, it is necessary to make the thickness of the phosphor 73 on the top surface smaller than t1. In this case, although it depends on the concentration of the phosphor paste, the thickness of the phosphor on the top surface is 20 μm or less. Since the thickness is small, there is a problem that the variation in the thickness greatly affects the variation in the chromaticity.
[0008]
As the phosphor 73, a YAG phosphor is generally used. The temperature distribution at the time of light emission is considerably different between the blue composite light-emitting element in which the blue LED 72 is mounted on the submount element 71 and the white composite light-emitting element 70 in which the blue LED 72 is further covered with a phosphor paste. At the time of applying a current of 20 mA, the temperature covered by the phosphor paste becomes higher by about 20 ° C or less (at the maximum value of the temperature distribution) than that not covered by the phosphor paste. At this time, the portion having the highest temperature is the portion of the phosphor paste. This is due to the poor heat dissipation of the phosphor paste, but also to the poor emission quantum efficiency of the YAG-based phosphor of 28%.
[0009]
That is, the energy excited by absorbing the blue light of the LED chip is converted into light at a rate of 28%, and the rest is released as heat or the like. Covering the periphery of the blue LED with the phosphor as described above raises the temperature of the blue LED, and also causes a problem that the luminous efficiency is reduced and the reliability is deteriorated.
[0010]
Therefore, an object of the present invention is to provide a composite light emitting device that suppresses a rise in temperature as a whole and makes the chromaticity of a chip uniform.
[0011]
[Means for Solving the Problems]
In the composite light emitting device of the present invention, a resin portion containing a fluorescent substance is applied only on the upper surface.
[0012]
According to the present invention, it is possible to obtain a composite light-emitting device that makes the chromaticity of a chip uniform while suppressing the overall temperature rise.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
The invention according to claim 1 of the present invention is directed to a semiconductor light emitting element having a main light extraction surface on the upper side, a submount element having the semiconductor light emitting element mounted thereon, and converting an emission wavelength of the semiconductor light emitting element to another wavelength. And a resin portion coated only on the upper surface of the light emitting element disposed on the submount element, the resin portion having a temperature that tends to rise. Since it is applied only to the upper surface and not to the side surfaces, it has the effect of suppressing the temperature rise of the element.
[0014]
Hereinafter, an embodiment of the present invention will be described with reference to FIG.
[0015]
(Embodiment 1)
FIG. 1A is a plan view of the composite light emitting device according to the first embodiment of the present invention, and FIG. 1B is a front view of the composite light emitting device.
[0016]
In FIG. 1, a composite light emitting element 1 includes a GaN LED element 3 which is an example of a blue light emitting semiconductor light emitting element having a main light extraction surface 2 on the upper side, a submount element 4 on which the GaN LED element 3 is mounted, and a sub light emitting element. The GaN LED device 3 includes a resin portion 6 applied over the upper surface (main light extraction surface 2) of the GaN LED device 3 disposed on the mount device 4.
[0017]
The GaN LED element 3 is formed in a square shape having a side of about 0.3 mm when viewed from above, and a GaN buffer layer, an n-type GaN layer, an n-type AlGaN layer, and an InGaN SQW are formed on the upper surface of the sapphire substrate. It has a quantum well structure in which a layer, a p-type AlGaN layer, and a p-type GaN layer are sequentially stacked. The upper surface of the n-type GaN layer is formed in a staircase composed of a lower portion and an upper portion, and an n-electrode made of V and Al is formed on the upper surface of the n-type GaN layer in the lower portion. On the upper surface of the n-type GaN layer in the upper stage, the above-described n-type AlGaN layer, an InGaN SQW layer, a p-type AlGaN layer, and a p-type GaN layer are sequentially stacked. A p-electrode made of Rh and Au is formed on the upper surface of the p-type GaN layer. Since the GaN LED element 3 is formed using an insulating sapphire substrate, both electrodes are formed on the epi-surface on the upper surface side of the sapphire substrate.
[0018]
The submount element 4 is formed in a rectangular shape of about 0.4 mm × 0.6 mm in plan view, and the GaN LED element 3 is mounted so as to overlap the submount element 4 made of a Si diode element. The GaN LED element 3 has a translucent sapphire substrate facing upward, and this is used as the main light extraction surface 2. Further, the p-electrode and the n-electrode provided on the lower surface are electrically connected to the n-electrode and the p-electrode of the submount element 4 via the microbumps 7, respectively, and are fixed by welding the electrodes and the microbumps. ing. Further, a bonding pad portion is formed on a part of the p-electrode of the submount element 4, and the back electrode and the bonding pad portion are connected to an external member. In addition, a resin containing a fluorescent substance that converts the emission wavelength of blue light of the GaN LED element 3 to a complementary yellow-green wavelength is applied so as to cover only the main light extraction surface 2 of the GaN LED element 3. , Formed in a flat plate shape. The most suitable coating method is screen printing capable of patterning. In addition, for example, a potting method using a dispenser is also possible. The applied resin is dried to form the resin portion 6.
[0019]
When the resin containing the phosphor is completely absent on the side surface, the thickness of the phosphor on the top surface is about 30 μm, and the chromaticity coordinate x value of the light passing through the resin portion 6 is 0, although it depends on the concentration of the phosphor paste. .4. In this case, when the variation in the thickness of the phosphor on the top surface is ± 1.5 μm, the variation in the chromaticity x is ± 0.009.
[0020]
On the other hand, when a resin is provided on the side surface and the thickness of the side surface is made larger than the thickness of the top surface, the thickness of the top surface is 20 μm or less and the chromaticity coordinate x value is around 0.3. When the thickness variation in this case is ± 1.5 μm, the chromaticity x variation is ± 0.018.
[0021]
Therefore, by reducing the thickness of the resin portion 6 on the side surface, the chromaticity variation is reduced, and when there is no resin on the side surface, the chromaticity variation is reduced to about half.
[0022]
In addition, the resin portion 6 having a high temperature separates from the side surface of the GaN LED element 3, and the temperature rise of the GaN LED element 3 is prevented.
[0023]
【The invention's effect】
As described above, according to the present invention, the resin portion, whose temperature tends to rise, is applied only to the upper surface and not to the side surface, so that the temperature rise of the element can be suppressed.
[Brief description of the drawings]
FIG. 1A is a plan view of a composite light emitting device according to a first embodiment of the present invention; FIG. 1B is a front view of the composite light emitting device; FIG. FIG. 2B is a front sectional view of the composite light emitting device.
Reference Signs List 1 composite light-emitting element 2 main light extraction surface 3 GaN LED element (semiconductor light-emitting element)
4 Submount element 6 Resin part 7 Micro bump

Claims (1)

A semiconductor light emitting element having the upper side as a main light extraction surface,
A submount element on which the semiconductor light emitting element is mounted,
A resin portion containing a fluorescent substance that converts the emission wavelength of the semiconductor light emitting element to another wavelength, and having a resin portion applied so as to cover only the upper surface of the semiconductor light emitting element disposed on the submount element. Composite light emitting device.

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