JP2006319061A - Semiconductor light emitting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor light emitting apparatus with which light can efficiently be taken out from a light emitting element. <P>SOLUTION: The semiconductor light emitting apparatus is provided with an LED chip 11; a sapphire substrate 21 in which the LED chip 11 is placed by making a main light emitting face 12 upside-down, and which has a recess 22 in a position confronted with the main light emitting face 12; and resin 31 comprising phosphor with which the recess 21 of the sapphire substrate 21 is filled, which absorbs emitted light from the LED chip 11 and converts luminescence wavelength. Color mixture of light emitted from the phosphor of resin 31 is discharged outside from a face opposite to the main light emitting face of the LED chip 11. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a semiconductor light emitting device.

  In general, a semiconductor light emitting device, for example, a light emitting diode has a so-called transmission structure in which a light emitting surface of a light emitting element is placed on a support substrate and the light emitting element is covered with a resin containing a phosphor. However, in this transmissive structure, the light emitted from the phosphor in the vicinity of the light emitting element having the largest light absorption is scattered by the phosphor or secondarily absorbed by the phosphor before being extracted to the outside. There is a problem that light emission cannot be extracted efficiently.

In addition, a reflective plate is provided on the support substrate, a light emitting element is placed on the support substrate in a concave portion formed by the reflective plate, and a resin containing a phosphor is filled in the concave portion so that only the upper surface of the light emitting element is provided. In addition, there is a reflective structure in which light emitted from the bottom surface and side surfaces of the light emitting element is extracted on the top surface (see, for example, Patent Document 1). However, in this reflection type structure, it is possible to take out a part of light emission by reflection, and it is basically a transmission type that takes out light from the upper surface of the light emitting element. Therefore, as with the transmissive type, the light emitted from the phosphor is scattered or secondarily absorbed by the phosphor before being extracted to the outside. There is a limit in the reflective structure.
JP 2002-94128 A (5th page, FIG. 6)

  An object of this invention is to provide the semiconductor light-emitting device which can extract light efficiently from a light emitting element.

  In order to achieve the above object, a semiconductor light-emitting device of one embodiment of the present invention includes a light-emitting element, the light-emitting element placed with the main light-emitting surface facing downward, and a recess at a position facing the main light-emitting surface. A light emitting device that includes a support base and a resin that is filled in a concave portion of the support base and absorbs light emitted from the light emitting element and converts a light emission wavelength; The light is emitted from the surface opposite to the light emitting surface of the element to the outside.

  According to the present invention, it is possible to efficiently extract light from a light emitting element.

  Embodiments of the present invention will be described below with reference to the drawings. The semiconductor light emitting device of each embodiment will be described by taking a white light emitting diode as an example.

  FIG. 1 is a perspective view schematically showing the structure of a white light emitting diode according to Example 1 of the present invention, and FIG. 2 is a plan view of the light emitting surface side of the light emitting element. Moreover, FIG. 3 is sectional drawing which shows the structure of the white light emitting diode which concerns on Example 1 of this invention.

Hereinafter, the white light emitting diode according to the first embodiment will be described with reference to FIGS. 1 to 3. As shown in FIGS. 1 and 3, the white light emitting diode according to the present embodiment includes an LED chip 11 that is a light emitting element, A sapphire substrate 21 which is a support substrate having a concave portion 22 at a position opposed to the main light emitting surface, the light emitting element being placed with the main light emitting surface facing downward, and a resin containing a phosphor filled in the concave portion 22 31 and a substrate 25 on which the sapphire substrate is placed.

  First, the LED chip 11 emits ultraviolet light 15, and a cathode electrode 13 and an anode electrode 14 for supplying power are formed on the upper surface, which is the main light emitting surface 12, as shown in FIG. 2. . Here, the LED chip 11 has a structure in which a GaN / InGaN PN junction is formed on a SiC substrate, a GaN substrate, or a sapphire substrate by a MOCVD (Metal Organic Chemical Vapor Deposition) method.

  The support substrate 21 is a sapphire substrate that is transparent to the ultraviolet light 15 emitted from the LED chip 11. In the present embodiment, a sapphire substrate is used as the support substrate 21, but AlN, GaN, diamond, or the like, which is a material transparent to ultraviolet light, may be used. The sapphire substrate 21 is provided with a recess 22 for sealing a resin containing a phosphor at the center of the upper surface.

  The recess 22 is formed in substantially the same shape and size as the main light emitting surface 12 of the LED chip 11 excluding the cathode electrode 13 and the anode electrode 14 of the LED chip 11.

  A cathode electrode pattern 23 and an anode electrode pattern 24 for electrically connecting the LED chip 11 are provided on the upper surface of the sapphire substrate 21 around the recess 22.

  As shown in FIG. 3, the LED chip 21 is placed on the concave portion 22 of the sapphire substrate 21 so that the main light emitting surface faces downward and faces the concave portion 21, and the cathode electrode 13 of the LED chip 10 and the sapphire substrate. 21 cathode electrode pattern 23, and anode electrode 14 and anode electrode pattern 24 are each flip-chip bonded with a solder material such as In.

  Further, the cathode electrode pattern 23 and the anode electrode pattern 24 are electrically connected to an electrode 27, for example, a strip line, laid on the substrate 25 by a wire 26 such as Au, for example, by wire bonding. Then, electric power is supplied from the main power source to the LED chip through wiring (not shown) laid on the substrate from the strip line 27. Here, the cathode electrode pattern 23 and the anode electrode pattern 24 may be connected to the electrodes by bumps other than wire bonding.

  Further, in the recess 22 of the sapphire substrate 21, a resin 31 containing a phosphor that converts the wavelength of the ultraviolet light 15 emitted from the LED chip 11 into white light 16 is in contact with the main light emitting surface 12 of the LED chip 11. The main light emitting surface 12 of the LED chip 11 is in contact with the resin 31 containing the phosphor in the recess 22 of the sapphire substrate 21.

  In the present example, the resin 31 was prepared by dispersing phosphors of three kinds of emission colors, green light emitting phosphor, blue light emitting phosphor, and red light emitting phosphor, with a total weight of 50% with respect to the silicone resin. Is. The green light emitting phosphors are rare earth phosphates and zinc silicates, the blue light emitting phosphors are alkaline earth phosphates, and the red light emitting phosphors are green yttrium oxide and yttrium borate. A system is used.

  In the white light emitting diode having the above structure, when power is supplied to the LED chip 11, the LED chip 11 emits ultraviolet light 15 from the main light emitting surface 12 toward the resin 31 in the recess 22 of the sapphire substrate 21. Most of the ultraviolet light 15 emitted from the main light emitting surface 12 of the LED chip 11 is absorbed by the phosphor in the resin 31 portion in contact with the main light emitting surface 12, and becomes light of three colors of green, blue, and red. The wavelengths are converted, and the three colors of light are mixed and converted into white light 6, which is emitted to the outside from the surface opposite to the main light emitting surface of the LED chip 11.

  At this time, the resin containing the phosphor and the main light emitting surface is in contact with each other, the wavelength is converted in the direction opposite to the direction of the main light emitting surface and white light is emitted, and the white light is hardly transmitted to the resin containing the phosphor. Therefore, it is possible to suppress the influence of loss due to scattering or secondary absorption by the phosphor.

  Further, a part of the ultraviolet light 15 that has advanced into the recess 22 is scattered and secondarily absorbed by the phosphor inside the recess, and almost no light is emitted in the opposite direction.

  FIG. 4 shows a comparison of the white light output between the white light emitting diode of this embodiment and the conventional transmissive white light emitting diode, and the depth of the recess 22, that is, the thickness T of the resin 31 in the white light emitting diode of this embodiment. It is a characteristic view which shows the relationship between a white light output. In this characteristic diagram, the vertical axis represents the white light output, and the horizontal axis represents the thickness T of the resin 31. Also, the solid line connecting the plots of the square marks in the figure is the white light output of the white light emitting diode in this example, and the circles are the conventional transmissive white light emission when the resin thickness T is 0.5 mm. The white light output of the diode is shown.

  Here, the conventional white light emitting diode uses a main light emitting surface facing upward and sealed with a resin in which a phosphor is dispersed on the main light emitting surface. A resin in which three types of phosphors of green, blue and red were dispersed in a total amount of 50% by weight with respect to the silicone resin was used.

  As is clear from FIG. 4, when the resin thickness is 0.55 mm, the white light output of the white light emitting diode of this example is 0.83 [arb. Unit], which is the white color of the conventional white light emitting diode. Compared with optical output 0.65 [arb. Unit], it is improved by about 27%.

  Furthermore, in the white light emitting diode of this embodiment, the white light output is increased by adjusting the thickness of the resin 31, that is, the depth T of the concave portion 22. In the range of 2.5 mm, the white light output becomes maximum, and a white light output about 1.8 times that of the conventional white light emitting diode can be expected.

  In addition, the optimum value of the white light output is set by the types of green, blue and red phosphors and the dispersion concentration with respect to silicone, and the depth of the concave portion 22 is adjusted according to the optimum value so that light can be efficiently extracted. It becomes possible.

  As described above, according to the white light emitting diode of the present embodiment, the sapphire substrate 21 is provided with the recess 22 and the recess 22 is filled with the resin 31 containing the phosphor, and the main light emitting surface is formed on the recess 22. By placing the main light emitting surface 12 in contact with the resin 31 and placing the main light emitting surface 12 in contact with the resin 31, the light emitted from the main light emitting surface 12 is changed from the main light emitting surface 12 by the resin 31 containing a phosphor. Since light can be emitted from the phosphor in the opposite direction, loss due to scattering and secondary absorption by the phosphor when passing through the resin containing the phosphor can be suppressed, and high white light output is achieved. A semiconductor light emitting device can be provided.

  In addition, since the LED chip 11 and the sapphire substrate 21 are connected by a flip chip and no electrode is provided in the white light emission direction, a shadow portion with respect to white light emission is not generated, and a high white light output can be obtained.

  Next, a white light emitting diode according to Example 2 of the present invention will be described with reference to FIGS. FIG. 5 is a perspective view schematically showing the structure of a white light emitting diode according to Example 2 of the present invention. Moreover, FIG. 6 is sectional drawing which shows the structure of the white light emitting diode which concerns on Example 2 of this invention.

  The difference between the present example and the first embodiment is that a back-emitting LED chip 41 is used as the light emitting element. That is, in the backside light emitting LED chip 41, the cathode electrode 43 and the anode electrode 44 are formed on the upper surface opposite to the main light emitting surface 42, that is, the white light extraction surface. Further, a cathode electrode pattern 53 and an anode electrode pattern 54 are provided at the peripheral corners of the sapphire substrate 51, and a fixing pattern 55 is provided at each corner of the recess 52.

  5 and 6, the LED chip 41 is fixed to the sapphire substrate 51 with the fixing pattern 55 with the main light emitting surface 42 facing the concave portion 52, and the sapphire substrate 51 and the cathode electrode 43 of the LED chip 41, Unlike the first embodiment, the anode electrode 44 and the anode electrode 44 are connected to the cathode electrode pattern 53 and the anode electrode pattern 54 of the sapphire substrate 51 by wire bonding, for example, by wires 26 such as Au. Other configurations are the same as those in the first embodiment.

  Similarly to the first embodiment, the white light-emitting diode having the above structure is converted into white light by the phosphor of the resin 31 so that the ultraviolet light 15 emitted from the main light-emitting surface 42 of the LED chip 41 is converted into white light. Emits white light 16 from the opposite surface. The white light output is changed by adjusting the depth of the recess 52 provided in the sapphire substrate 51 as in the first embodiment.

  According to the white light emitting diode of the present embodiment, a high white light output can be obtained as in the first embodiment. Further, since the cathode 43 and the anode electrode 44 are provided on the upper surface opposite to the main light emitting surface, and the connection between the LED chip 41 and the sapphire substrate 51 is connected by wire bonding, the phosphor is dispersed as compared with the first embodiment. The contact surface between the resin and the main light emitting surface of the LED chip 41 or the opposing surface can be widened, and the white light output can be increased.

  Note that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  For example, in each of the above embodiments, a white light emitting diode using an ultraviolet LED chip and a phosphor has been described as an example. However, the present invention is not limited to this, and a blue LED chip and a phosphor are used. The same effect can be expected when applied to the white light emitting diode used. Further, the present invention can be applied not only to white light emitting diodes but also to mixed color light emitting diodes that emit mixed color light by combining LED chips that emit other colors and phosphors.

  Further, in each of the above embodiments, the main light emitting surface of the LED chip is brought into contact with the resin, but the resin may be separated from the main light emitting surface.

  Further, in each of the above embodiments, the ultraviolet light emitted from the main light emitting surface is not wavelength-converted and emitted as white light by the resin in which the phosphor is dispersed. To be released. Therefore, white light 19 not including the ultraviolet light 13 can be extracted by attaching an ultraviolet filter for preventing leakage of ultraviolet rays to the outer periphery of the semiconductor light emitting device according to the present embodiment.

The perspective view which shows typically the structure of the white light emitting diode which concerns on Example 1 of this invention. The top view of the light emission surface side of a light emitting element. Sectional drawing which shows the structure of the white light emitting diode which concerns on Example 1 of this invention. The graph which shows the relationship between the white light output of the white light emitting diode which concerns on Example 1 of this invention, and the depth of a recessed part. The perspective view which shows typically the structure of the white light emitting diode which concerns on Example 2 of this invention. Sectional drawing which shows the structure of the white light emitting diode which concerns on Example 2 of this invention.

Explanation of symbols

11, 41 LED chip 12, 42 Main light emitting surface 13, 43 Cathode electrode 14, 44 Anode electrode 15 Ultraviolet light 16 White light 21, 51 Sapphire substrate 22, 52 Recess 23, 53 Cathode electrode pattern 24, 54 Anode electrode pattern 25 Substrate 26 Wire 27 Electrode 31 Resin 55 Containing Phosphor 55 Adhering Pattern

Claims (4)

A support substrate having a recess;
A resin containing a phosphor that fills the concave portion of the support substrate and converts the emission wavelength;
A light emitting element mounted on the support base and having a main light emitting surface opposed to the recess;
A semiconductor light emitting device, wherein the phosphor absorbs light emitted from the light emitting element and emits a color mixture of light emitted from the phosphor to the outside from a surface opposite to the main light emitting surface of the light emitting element . The semiconductor light emitting device according to claim 1, wherein the resin is in contact with or faces a main light emitting surface of the light emitting element. The semiconductor light emitting device according to claim 1, wherein the light emitting element has an electrode on the main light emitting surface and is connected to the support substrate by flip chip bonding. 3. The semiconductor light emitting device according to claim 1, wherein the light emitting element has an electrode on a surface opposite to the main light emitting surface and is connected to the support substrate by wire bonding.

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