JP2008198702A - Color converting light-emitting element and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem wherein a longer time is required for alignment on the occasion of placing a fluorescent material chip on a light-emitting element. <P>SOLUTION: A frame is formed in the external circumference of an optical function layer so as to form an alignment structure in the part where the frame is in contact with the light-emitting element. For the frame, silicon (Si) is preferably used in addition to glass, ceramics, and resin. The optical function layer may be formed of a light shielding film, a light dispersing material, and a micro-lens in addition to a fluorescent material. The function of alignment structure with the frame provides such a merit that the light-emitting device combining the light-emitting element and the optical function layer can be manufactured with simplified processes. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wavelength conversion type light emitting device that converts light emitted from a light emitting diode (hereinafter referred to as LED) by a phosphor to obtain light of other wavelengths.

  In recent years, so-called white LEDs that obtain white light by combining ultraviolet or blue LEDs and the like with phosphors that convert light emitted from the LEDs into other wavelengths have been widely used. The products used are, for example, liquid crystal backlights and small illuminations.

  In order to prevent the occurrence of so-called color unevenness, in which the color of the white LED changes depending on the viewing direction, several techniques for uniformly forming the phosphor layer have been developed.

Patent Document 1 discloses a phosphor chip formed separately on an LED chip and engaged with a claw. Therefore, there is an advantage that the phosphor chip can be pressed against the light emitting element and fixed.
JP2000-022222

  In any of the above documents, a phosphor chip is placed on an LED chip. However, both the LED chip and the phosphor chip are smaller than 1 mm square, and there is a problem that it takes time for alignment in the placing process.

  The subject includes an optical function layer, a frame portion that surrounds the outer periphery of the optical function layer and has an alignment structure, and a light emitting element, and the light emitting element includes the frame portion and the optical function layer. This is solved by the structure of the light emitting device of the present invention, which is placed in a state of being aligned by the alignment structure.

  The optical functional layer may include a phosphor that receives light emitted from the light emitting element and emits fluorescence having a longer wavelength than the emission wavelength.

  The optical function layer may include a scattering material that receives light emitted from the light emitting element and scatters the light.

  Further, the optical function layer may form a light shielding portion that blocks part of light emitted from the light emitting element.

  The optical functional layer may have a microlens formed on the surface thereof.

  Further, the alignment structure may take a step structure or a protrusion structure so that it can be fitted with the LED chip.

  Moreover, you may form a frame part with either glass, a ceramic, or resin.

  The frame portion may be formed of silicon (Si).

  The frame part may form an electrical connection part between the light emitting element. In this case, an external connection terminal is formed for further connection to an electric circuit such as an external power source.

  In addition, when the frame portion is formed of silicon, an electrical connection portion is provided between the frame and the light-emitting element, and an electrostatic protection element for the light-emitting element such as a capacitor or a diode is formed by a known semiconductor process. Also good.

  In addition, a light shielding portion that blocks a part of light emission of the light emitting element may be formed in the frame portion.

  According to the configuration of the present invention, when the frame portion holding the optical function layer is placed on the light emitting element, there is an effect that positioning is simplified and time is not required.

  The optical functional layer includes a phosphor that receives light emitted from the light emitting element and emits fluorescence having a wavelength longer than the light emission wavelength, thereby obtaining, for example, a mixed light of both light emitted from the light emitting element and light emitted from the phosphor. be able to. For example, it is possible to obtain white light by using a blue LED as a light emitting element and using a YAG: Ce phosphor that absorbs blue light and emits yellow fluorescence as a phosphor.

  By including a scattering material that receives light emitted from the light emitting element and scatters the light in the optical functional layer, the influence of uneven light emission in the surface of the light emitting element can be reduced and a uniform light emitting surface can be obtained. For example, when a light emitting device having a size of 1 mm square or more is used, there may be a problem in the uniformity of the light emission intensity in the surface of the light emitting device, which is useful for reducing this.

  By forming a light-shielding portion that blocks part of light emitted from the light-emitting element in the optical functional layer, the size as the light source can be reduced, or a predetermined light distribution can be obtained. For example, by forming the light-shielding part shape so that the shape of the light-emitting part becomes the shape of the passing light distribution of the vehicle lamp, a vehicle headlamp using a semiconductor light-emitting element as a light source can be made smaller. Is useful.

  By forming a microlens on the surface of the optical functional layer, the light distribution of light emitted from the light emitting element can be controlled to a desired pattern.

  If the alignment structure is a stepped or protruding structure, it can be formed more easily by etching or the like.

  It is preferable from the viewpoint of manufacturing cost and ease of processing that the frame portion employs any of glass, ceramic, and resin.

  The frame portion is preferably provided with an electrical connection with the light emitting element, so that the frame portion and the light emitting element can be handled as an integrated element.

  When the frame is formed of silicon, in addition to electrical connection with the light emitting element, an electrostatic protection element such as a capacitor or a diode can be further formed. In the manufacturing process after combining with the frame, It is possible to prevent the element from being electrostatically destroyed.

  A desired light distribution can be obtained by adjusting the shape of the frame portion during processing and including a light shielding portion.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  (First Embodiment) The left side of FIG. 1 is a perspective view showing the first embodiment of the present invention, and the right side is a sectional view taken along the dotted line A-A '. The light emitting element 9 includes a semiconductor layer 5 formed on the substrate 6, a p-type ohmic electrode 3 connected to the p-type layer of the semiconductor layer 5, and an n-type ohmic electrode 4 connected to the n-type layer. And an auxiliary electrode 7 formed on the surface of the p-type layer for the purpose of diffusing the current from the p-type ohmic electrode 3. The auxiliary electrode 7 may be replaced by forming a transparent electrode on the p-type layer surface. Further, the auxiliary electrode 7 may be formed on the transparent electrode.

  Usually, an Au wire or the like is wire-bonded to the p-type ohmic electrode 3 and the n-type ohmic electrode 4, and the Au wire or the like is connected to an external circuit such as a power source. When a current is applied via an Au wire or the like, the light emitting element 9 emits light at a wavelength determined by the configuration of the semiconductor layer 5.

  As the light emitting element 9, for example, a gallium nitride blue light emitting diode using InGaN as a light emitting layer is preferably used. Such a light emitting diode can change the emission wavelength from green to near ultraviolet light according to the In composition of the light emitting layer. Therefore, when a phosphor layer is used as the optical functional layer, an optimum wavelength may be selected according to the excitation wavelength of the phosphor suitable for the purpose of the present invention. In this case, besides the gallium nitride-based light-emitting diode, a zinc oxide-based light-emitting element, a SiC-based light-emitting element, a ZnSe-based light-emitting element, or the like can be used as the light-emitting element of the present invention.

  The frame part 2 holds the phosphor layer 1 as an optical functional layer inside thereof. On the lower side of the frame portion 2, a step-like alignment structure 8 that matches the size of the light emitting element 9 is formed. Further, the frame portion 2 has a shape in which corresponding portions are cut out so as not to cover the p-type ohmic electrode 3 and the n-type ohmic electrode 4 which are portions for wire bonding. The phosphor layer 1 has a thickness of about 10 to 700 μm, although it varies depending on the composition and concentration of the phosphor.

  When either the p-type ohmic electrode 3 or the n-type ohmic electrode 4 is on the lower surface of the light-emitting element 9, it is not necessary to cut out the corresponding part, and the structure becomes simpler. When a so-called flip chip type mounting structure in which both the p-type ohmic electrode 3 and the n-type ohmic electrode 4 are on the lower surface of the light emitting element 9 is employed, the shape of the frame portion 2 is a square or rectangular shape that matches the outer shape of the light emitting element 9 It is only necessary to do.

  The frame portion 2 is combined with the upper surface of the light emitting element 9 so that the phosphor layer 1 is not displaced. When a current is applied to the light emitting element to emit light, light emitted from the upper surface of the light emitting element 9 enters the optical function layer 1. The phosphor layer 1 absorbs a part of this light and emits fluorescence having a wavelength different from the wavelength of the incident light. As a result, the light from the light emitting element 9 which has entered the phosphor layer 1 and has not been converted, and the converted light form mixed color light and are emitted to the outside of the device. Depending on the configuration of the phosphor layer 1 and the configuration of the light emitting element 9, the phosphor layer 1 absorbs substantially all of the light emitted from the light emitting element 9, and converts it to another wavelength. In this case, only the fluorescence from the phosphor layer 1 is emitted to the outside of the device.

  The frame 2 may be any material that holds the phosphor layer 1 and is easy to handle when placed on the light emitting element 9. In particular, when the size of the light emitting element 9 is small, the size of the alignment structure 8 is small. Therefore, a material that is easy to be finely processed is suitable. Furthermore, when it is desired to apply a current exceeding the rating to the light emitting element 9 to obtain a high light output, it is more preferable that the light emitting element 9 is not easily thermally denatured because of the heat generation of the light emitting element 9. Examples of such a material include glass, ceramic, and resin. Silicon (Si) can be suitably used because it is easy to finely process and has heat resistance, and is also inexpensive. When glass or silicon is used, the frame portion 2 can be manufactured by applying patterning by a photolithography technique and a normal etching technique to a glass substrate or a silicon wafer. In the case of ceramic, the raw material may be pressed and fired with a mold of a collective substrate in which openings and alignment structures are arranged vertically and horizontally. If it is resin, a normal molding technique can be applied as needed.

The phosphor layer 1 is made of a resin mixed with a phosphor serving as a binder. When a blue light emitting diode is used as the light emitting element 9 and a yellow phosphor is combined with this to obtain white light, YAG: Ce, (Sr, Ca, Ba) ₂ SiO ₄ : Eu or the like is preferably used. Further, when a blue light emitting diode is used as a light emitting element and white light is obtained by combining a green phosphor and a red phosphor, preferably, (Sr, Ca) Ga ₂ S ₄ : Eu, CaAlSiN ₃ : Eu or (Sr, Ca) S: Eu or the like is used as the red phosphor.

  As resin used as a binder, heat resistance and light resistance are required. In particular, a silicone resin satisfies this requirement and is preferably used. Among the silicone resins, the soft and sticky resin that continues to have surface tackiness after curing is such that the phosphor layer 1 sticks to the light emitting element 9, and thus the phosphor layer 1 and the frame 2 prepared separately are emitted. There is no need to use an adhesive material when placing the element 9. Therefore, there is an advantage that this process is simple.

  In order to form the phosphor layer 1 in the frame portion 2, an aggregate substrate having a plurality of openings formed vertically and horizontally may be manufactured, and the openings may be filled with a phosphor-containing resin. Then, the individual frame portions 2 can be manufactured by cutting out the frame portions including the openings in a dicing process and dividing them into pieces.

  A scattering layer containing a scattering material can also be selected as the optical functional layer. In particular, in an element such as the light emitting element 9 that requires in-plane diffusion of current to the extent that the auxiliary electrode 7 is required, there is a problem that light emission uniformity in the element plane cannot be obtained well. This is particularly effective when a semiconductor light emitting device having a size of 1 mm square or more is used.

  Furthermore, a microlens can be formed on the surface as the optical functional layer. In particular, it will be effective in a field that requires a small electronic component that requires a certain amount of light distribution characteristics with a single light emitting element.

  (Second Embodiment) The left side of FIG. 2 is a perspective view showing a second embodiment of the present invention, and the right side is a sectional view taken along the dotted line B-B '. In addition, the same number is attached | subjected to the same part, and description other than the characteristic peculiar to this embodiment is abbreviate | omitted hereafter.

  The frame portion 2 is formed with pad portions 10a and 11a for electrical connection with the light emitting element 9 and terminal portions 10c and 11c for connection with an external circuit or the like via wiring on the side surface of the frame portion 2. Yes. Further, a pad portion 10 b is formed on the p-type ohmic electrode 3 of the light emitting element 9, and a connection pad portion 11 b is formed on the n-type ohmic electrode 4, corresponding to the pad portions 10 a and 11 a of the frame portion 2. ing.

  By accurately arranging the frame portion 2 on the light emitting element 9 by using the alignment structure 8, the pad portions 10 a and 11 a are correctly placed in contact with the pad portions 10 b and 11 b of the light emitting element 9. It will be. In this state, the pad portion is heated to ensure electrical connection, so that the frame portion 2 can be easily fixed and the terminal portions 10c and 11c can be connected to an external circuit or the like. .

  Here, when the frame portion 2 is formed of silicon, a diode or a capacitor can be formed as an electrostatic protection element between the terminal portions 10c and 11c by performing doping or the like on silicon in advance. . Such a configuration is particularly useful when using a gallium nitride based semiconductor light emitting device that tends to be electrostatically weak.

  (Third Embodiment) The left side of FIG. 3 is a perspective view showing a third embodiment of the present invention, and the right side is a sectional view taken along the dotted line C-C '. In FIG. 3, the opening shape of the frame portion 2 is a unique shape because the light shielding portion 12 is formed. This opening shape forms a cut-off by the light-shielding part 12 in order to realize the passing light distribution of the vehicle headlamp. The light-shielding portion 12 can be easily formed by simply forming a pattern when the frame portion 2 is manufactured, for example, when a photolithography technique is used.

  In practice, when a vehicle headlamp is realized using the light emitting device of this embodiment, a projection lens (not shown) having a focal point in the vicinity of the cut-off portion is required.

  The shape of the light shielding part 12 can be an appropriate shape according to the purpose. For example, when a horizontally long light distribution is required for a vehicle headlamp, the light shielding portion 12 may be formed so that the opening shape is rectangular. Further, as a decorative light emitting device, for example, a star-shaped opening shape can be freely used.

  On the upper surface of the light shielding part 12 and the frame part 2, heat radiation coating or anodizing may be performed to promote infrared radiation and the like, which may be useful for heat radiation. In particular, when the light emitting device of the present embodiment is used as a vehicle headlamp, a large current is applied, and thus the light emitting element 9 generates a great amount of heat. When the optical functional layer 1 includes a phosphor, the phosphor itself also generates heat due to the Stokes shift of the phosphor. These can be one of means for releasing heat.

  In the present embodiment, the light shielding portion 12 is formed by making the opening shape of the frame portion 2 an appropriate shape. However, a light shielding film having an appropriate shape may be formed on the front surface or the back surface of the optical functional layer 1 instead.

  In the present embodiment, the light emitting element 9 takes a so-called flip chip bonding mounting form. In this case, the frame portion 2 is accurately arranged by the alignment structure 8 on the substrate 6 of the light emitting element 9. However, even if the p-type and n-type ohmic electrodes appear on the upper surface side as in the second embodiment, the effect of the present invention is not impaired. When the p-type and n-type ohmic electrodes are on the upper surface side, the terminal portions 10c, 11c and the like in the second embodiment may be formed in the light shielding portion 12.

  Examples of the present invention will be described below. In Example 1, a Si frame portion was produced.

  A single crystal Si wafer substrate (hereinafter simply referred to as an Si wafer substrate) having a (100) surface was patterned by photolithography so as to have a square opening shape. The patterning is as shown in FIG. Thereafter, the Si wafer substrate was processed by wet etching on the surface to be filled with the phosphor-containing resin. At the time of wet etching, crystal anisotropic etching using TMAH (Tetramethylammonium Hydroxide) as an alkaline etching solution was performed, whereby the (111) plane inclined to the inner side surface of the frame portion was exposed. The inclination angle of this surface is 54.7 ° with respect to the surface of the Si wafer substrate (125.3 ° when measured from the opening side).

  Thereafter, the back surface of the Si wafer substrate was patterned again as indicated by the dotted line in FIG. 4, and an opening was formed from the back surface side by reactive ion etching (RIE). Here, in order to produce the alignment structure, the etching pattern from the back surface side is made larger than the etching pattern from the front surface side of the Si wafer substrate. The Si wafer substrate had a thickness of 300 μm, and the opening shape was a square with a side of 960 μm on the front side and a square with a back side of 900 μm. Here, the depth etched from the front surface side and the depth etched from the back surface side were set to 150 μm, respectively, and therefore penetrated at the center in the thickness direction of the Si wafer substrate.

  Next, in order to prevent light absorption by the Si frame portion, an Ag reflection film was formed as a reflective material on the Si surface by an electrolytic plating method.

  FIG. 5 shows a state in which the YAG: Ce phosphor-containing resin is filled in the frame portion. Filling the phosphor-containing resin is achieved by squeezing the silicone resin, in which the phosphor particles are dispersed in advance, with a squeegee using the opening of the frame, so that a certain film thickness corresponding to the depth of the opening can be obtained. It was. Thereafter, the resin was cured and diced into individual pieces. As a result of dicing, the frame shown in FIG. 6 could be obtained as individual pieces. In FIG. 6, the lower half of the frame portion whose side surfaces are vertical due to etching by RIE is combined with the light emitting element. On the other hand, a YAG: Ce phosphor-containing resin is filled in the upper half of the frame portion whose side surfaces are inclined by wet etching.

  FIG. 7 illustrates a state in which an individual Si frame portion is disposed on a flip-chip mounted light emitting device. The frame was placed on the chip using the tackiness of silicone resin. Then, the light emitting device was able to be manufactured by sealing the whole containing a light emitting element and a frame part with a silicone resin.

It is a figure which shows the 1st Embodiment of this invention. It is a figure which shows the 2nd Embodiment of this invention. It is a figure which shows the 3rd Embodiment of this invention. It is a figure which shows the patterning of the Si wafer substrate in the Example of this invention. In the Example of this invention, it is a figure which shows having filled the fluorescent substance containing resin in the frame part. In the Example of this invention, it is the figure which showed typically the cross section of the frame part separated into pieces. In the Example of this invention, it is the figure which has arrange | positioned the frame part on the light emitting element.

DESCRIPTION OF SYMBOLS 1 Optical function layer 2 Frame part 3 P-type ohmic electrode 4 N-type ohmic electrode 5 Semiconductor layer 6 Substrate 7 Auxiliary electrode 8 Alignment structure 9 Light emitting element 10a Pad part 10b Pad part 10c Terminal part 11a Pad part 11b Pad part 11c Terminal part 12 light shielding part 13 Si (111) surface

Claims (11)

An optical functional layer;
A frame part that surrounds the outer periphery of the optical functional layer and is formed with an alignment structure;
A light emitting element;
Including
The light emitting device, wherein the frame and the optical functional layer are placed in a state of being aligned by the alignment structure.   The light emitting device according to claim 1, wherein the optical functional layer contains a phosphor.   The light emitting device according to claim 1, wherein the optical functional layer contains a scattering material.   The light emitting device according to claim 1, wherein the optical function layer includes a light shielding portion.   The light emitting device according to claim 1, wherein the alignment structure includes one of a step structure and a protrusion structure.   The light emitting device according to claim 1, wherein the frame portion is formed of any one of glass, ceramic, and resin.   The light emitting device according to claim 1, wherein the frame portion is made of silicon (Si).   8. The frame portion is formed with an electrical connection portion between the light emitting element and an external electrical terminal for connection with an external electrical circuit. The light emitting device according to 1.   The light emitting device according to claim 1, wherein the frame portion is provided with a heat dissipation coating.   The frame portion has an electrical connection portion formed between the light emitting element, an external electrical terminal for connection to an external electrical circuit, and a capacitor or a diode as an electrostatic protection element. The light-emitting device according to claim 7.   The light emitting device according to claim 1, wherein the frame portion has a light shielding portion.

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