JP5034342B2 - Light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting device of high output type that emits a mixed light such as white light with a small amount of fluctuation in emission of light and color of light. <P>SOLUTION: The light emitting device includes: a transmissive heat radiating member; a conductor wiring formed as a pattern on the front surface of the transmissive heat radiating member; a light emitting element flip-chip mounted to the conductor wiring; and a wavelength converting member covering the light emitting element. In the transmissive heat radiating member, an insulating and non-transmissive inorganic member is formed to a non-conductive wire forming region on the surface opposing to the light emitting element. The inorganic member may be extended up to an interface between the transmissive member and the conductor wire, and a distance between the mounting surface of the light emitting element and the inorganic member is preferably shorter than the thickness of the wavelength converting member from the other surface. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

The present invention relates to a light-emitting device having a light-emitting element that emits visible light and a wavelength conversion member that can convert light from the light-emitting element into other visible light.

As a light emitting device using a light emitting element such as a light emitting diode (hereinafter also referred to as “LED”) or a semiconductor laser (hereinafter also referred to as “LD”), for example, a light emitting element that emits visible light; A wavelength conversion member having a fluorescent material capable of absorbing at least part of light emitted from the light emitting element and emitting other visible light, and emitting a mixed color of these visible light A light-emitting device capable of satisfying the requirements is known.

In such a light emitting device that emits mixed color light, the light emitting element is mounted on the submount element or the base for the purpose of improving the color unevenness, and the thickness from the outer surface of the light emitting element becomes almost equal in all directions. Thus, forming a phosphor-containing resin is disclosed. Thereby, the wavelength conversion degree by a wavelength conversion member can be equalize | homogenized with respect to all the directions of the light emission direction of the said light emitting element.

JP 2005-311395 A

However, in the above light emitting device, when a large current is applied to obtain a high output, the phosphor-containing resin interposed between the light emitting element and the submount element thermally expands, and cracks occur in the members and their interfaces. As a result, the reliability of the light emitting device is reduced and the lamp is not lit.

Therefore, the present invention solves the above-mentioned problems, can maintain high reliability even when a large current is applied, and can emit mixed color light such as white light with little uneven emission or color unevenness. An object of the present invention is to provide a light emitting device.

In order to achieve the above object, a light-emitting device according to the present invention includes a light-transmitting heat radiating member, a conductor wiring patterned on the surface of the light-transmitting heat radiating member, and a light-emitting device flip-chip mounted on the conductor wiring. An element, and a wavelength conversion member that covers the light-emitting element,
The translucent heat radiating member is formed with an insulating and non- translucent inorganic member in a non-conductor wiring forming region on a surface facing the light emitting element, and the inorganic member is formed with the translucent heat radiating member. It extends to the interface with the conductor wiring .

Moreover, the inorganic member may extend to the interface between the translucent member and the conductor wiring. The inorganic member includes Ni ₂ O ₃ , SiC, C ₃ N ₄ , Ta ₂ O ₅ , SiO ₂ , SiN, AlN, Al ₂ O ₃ , ZrO ₂ , ZnO, TiO ₂ , Y ₂ O ₃ and Si ₃ N. It is preferably at least one selected from ₄ . The inorganic member is preferably a multilayer film. The multilayer film preferably has a light blocking layer and an insulating layer.

Moreover, it is preferable that the distance of the mounting surface of the said light emitting element and the said inorganic member is shorter than the thickness of the said wavelength conversion material from the other surface of the said light emitting element.

According to the light emitting device of the present invention, a high output light emitting device with high reliability and less color unevenness can be realized.

  The best mode for carrying out the present invention will be described below with reference to the drawings. However, the modes shown below exemplify a semiconductor device for embodying the technical idea of the present invention, and the present invention does not limit the semiconductor device to the following. Further, the present specification by no means specifies the members shown in the claims to the members of the embodiments. In particular, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in the embodiments are not intended to limit the scope of the present invention only to a specific description unless otherwise specified. It is just an example. Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. Furthermore, in the following description, the same name and symbol indicate the same or the same members, and detailed description thereof will be omitted as appropriate. Furthermore, each element constituting the present invention may be configured such that a plurality of elements are constituted by the same member and the plurality of elements are shared by one member, and conversely, the function of one member is constituted by a plurality of members. It can also be realized by sharing.

Embodiment 1 FIG.
FIG. 1 is a schematic cross-sectional view of the light-emitting device according to Embodiment 1 of the present invention. In the light emitting device 100 according to the first embodiment, the flip chip type light emitting element 110 having the positive electrode 111a and the negative electrode 111b on the same surface side, and the conductor wiring pattern 131 having the positive electrode 131a and the negative electrode 131b on the surface are formed. The wavelength conversion member 140 so that the light emitting element 100 is flip-chip mounted on the submount 130 via conductive adhesives 120a and 120b so as to cover the periphery of the light emitting element. Is formed.

[Light emitting element 110]
As a light emitting element in the present invention, an LED chip will be described here as the light emitting element. Examples of semiconductor light-emitting elements that constitute LED chips include those using various semiconductors such as ZnSe and GaN. When a fluorescent material is used, a short wavelength that can excite the fluorescent material efficiently is emitted. possible nitride semiconductor _{(in X Al Y Ga 1-} X-Y N, 0 □ X, 0 □ Y, X + Y □ 1) it is preferably exemplified. Examples of the semiconductor structure include a homostructure having a MIS junction, a PIN junction, and a pn junction, a heterostructure, and a double heterostructure. Various emission wavelengths can be selected depending on the material of the semiconductor layer and the degree of mixed crystal. In addition, a single quantum well structure or a multiple quantum well structure in which the semiconductor active layer is formed in a thin film in which a quantum effect is generated can be used.

  When a nitride semiconductor is used, a material such as sapphire, spinel, SiC, Si, ZnO or the like is preferably used for the semiconductor substrate. In order to form a nitride semiconductor with good crystallinity with high productivity, it is preferable to use a sapphire substrate. A nitride semiconductor can be formed on the sapphire substrate by MOCVD or the like. A buffer layer of GaN, AlN, GaAlN or the like is formed on the sapphire substrate, and a nitride semiconductor having a pn junction is formed thereon.

  As an example of a light emitting device having a pn junction using a nitride semiconductor, a first contact layer formed of n-type gallium nitride, a first clad layer formed of n-type aluminum nitride / gallium on a buffer layer, Examples include a double hetero structure in which an active layer formed of indium / gallium nitride, a second cladding layer formed of p-type aluminum nitride / gallium, and a second contact layer formed of p-type gallium nitride are sequentially stacked. . Nitride semiconductors exhibit n-type conductivity without being doped with impurities. When forming a desired n-type nitride semiconductor, for example, to improve luminous efficiency, it is preferable to appropriately introduce Si, Ge, Se, Te, C, etc. as an n-type dopant. On the other hand, when forming a p-type nitride semiconductor, the p-type dopants such as Zn, Mg, Be, Ca, Sr, and Ba are doped. Since nitride semiconductors are not easily converted to p-type by simply doping with a p-type dopant, it is preferable to reduce resistance by heating in a furnace or plasma irradiation after introducing the p-type dopant.

The light emitting element used in the present invention is a flip chip type light emitting element having both electrodes on the same surface side. In the light-emitting element 110 used in this embodiment, after a part of the n-type semiconductor is exposed from the p-type semiconductor layer side by a method such as etching, the p-type semiconductor layer and the exposed n-type semiconductor layer are exposed. The positive electrode 111a and the negative electrode 111b are formed by vapor deposition or sputtering, respectively. In the present embodiment, the negative electrode 111b is formed by exposing the n-type semiconductor so as to form a stripe parallel to each other, and the current flowing between the positive electrode 111a and the negative electrode 111b is configured to be uniform. ing.

Further, the surface area of the positive electrode 111a is configured to be larger than the surface area of the negative electrode 111b. Specifically, the positive electrodes 111a and the negative electrodes 111b are alternately arranged in a stripe shape, and the width of the positive electrode 111a is wider than the width of the negative electrode 111b. Thus, the light extraction efficiency of the light-emitting element can be improved by reducing the exposed region of the n-type semiconductor that does not contribute to the light emission of the light-emitting element and relatively increasing the region of the p-type semiconductor and the positive electrode 111a. .

The positive electrode 111a is preferably formed of a material that can reflect light from the light emitting element, and examples thereof include Ag, Al, Rh, and Rh / Ir. In addition, an oxide conductive film such as ITO (complex oxide of indium (In) and tin (Sn)), ZnO, or a metal thin film such as Ni / Au is formed on the entire surface of the p-type semiconductor layer. Can be formed. In this specification, the symbol “A / B” indicates that the metal A and the metal B are sequentially laminated by a method such as sputtering or vapor deposition. In addition, a multilayer electrode of Ti—Al—Ni—Au or W—Al—W—Pt—Au can be used for the negative electrode 111b formed on the exposed surface of the n-type nitride semiconductor layer. The thickness of the negative electrode is preferably 0.1 to 1.5 μm. Moreover, it is preferable to provide an insulating protective film such as SiO ₂ , Al ₂ O ₃ , ZrO ₂ , or TiO ₂ so as to cover the exposed surface other than the negative electrode.

[Translucent heat dissipation member 130]
The translucent heat radiating member 130 in this embodiment is provided with an insulating and translucent inorganic material 150 between the wiring pattern 131 and the wiring pattern 131 on which the light emitting element is conductively mounted on the upper surface side. The pattern extends to the inside and the lower surface side of translucent heat radiating member 130. Here, in this specification, translucency means that the transmittance per 1 mm thickness is 20% or more in the wavelength region of 300 to 700 nm. The transmittance is a value measured with a spectrophotometer.

The material of the translucent heat radiating member 130 is preferably an insulating material having a high thermal conductivity, such as AlN, Al ₂ O ₃ , Si, GaAs, BN, SiN, and C (diamond). In addition, it is preferable to use a material having a small difference in thermal expansion coefficient from that of the light-emitting element 110, and the influence of thermal stress generated between the light-transmitting heat dissipation member 130 and the light-emitting element 110 during manufacturing or use can be reduced. . For example, when a nitride semiconductor light emitting element is used, it is preferable to use a material containing aluminum nitride (AlN). A material having a function of an electrostatic protection element can also be used, and a material having Si (silicon) which is inexpensive is preferably used. (I think that you can clearly specify the conditions of each material (translucency, density, heat dissipation effect, etc.) on this side.) Here, the translucent heat dissipation member 130 contains impurities and the like. Although it is possible to reduce translucency, heat dissipation will fall, so that an impurity increases. Therefore, in the present invention, by forming an insulating and non-light-transmitting inorganic member only on the surface of the light-transmitting heat radiating member on the mounting surface side of the light-emitting element, the heat radiating property of the light-transmitting heat radiating member is lowered. The color unevenness of the light emitting device is suppressed without causing it. The present invention is also effective when the translucent heat radiating member is porous. When the translucent heat radiating member is porous, light passes through the internal cavity, and thus the color unevenness of the light emitting device increases. However, in the present invention, the surface of the translucent heat radiating member is insulative and transparent. By forming the light inorganic member, it is possible to suppress color unevenness of the light emitting device.

[Conductor wiring 131]
On the surface of the translucent heat radiating member 130, a positive conductor wiring 131a and a negative conductor wiring 131b are patterned. These materials are not particularly limited as long as they have conductivity. Ag, Al, Pt, Pd, which have high light reflectivity with respect to light from Au or silver-white metal, in particular, light emitting elements. Etc. are preferably used. Such a conductive pattern using silver-white metal can reflect the light from the light emitting element in the extraction direction and improve the light extraction efficiency of the light emitting device, while migration occurs. For this reason, it is necessary to increase the distance between the conductor wiring patterns. The invention of the present application can show a great effect in a light-emitting device in which such a light-reflecting conductor wiring pattern and a translucent heat radiating member are combined. Here, the metal used as the material of the conductor wiring 131 is preferably selected in consideration of good adhesion between the metals, so-called wettability. For the conductor wiring, a photoresist pattern is formed on the surface of the translucent heat radiating member in a region where no wiring is formed, and a Ti layer having a thickness of, for example, 10 nm is formed by a method such as electron beam evaporation, sputtering, or plating. A 1000 nm (1 μm) Au layer is deposited. Thereafter, the resist pattern is removed, and the metal layer deposited thereon is lifted off. As the wiring layer, Ni / Au, Al / Au, etc. can be used in addition to Ti / Au.

Further, the pattern of the conductor wiring extends from the surface on which the light emitting element of the translucent heat radiating member 130 is mounted to the opposite lower surface. In particular, when at least one through hole is provided in the thickness direction of the translucent heat radiating member, and the conductor wiring extends on the inner wall surface of the through hole, the heat radiating property of the translucent heat radiating member is further increased. Can be improved.

[Wavelength conversion member 140]
In the light emitting device of the present embodiment, the wavelength conversion member 140 is made of a resin containing a fluorescent material that is excited by the light emission wavelength from the light emitting element and emits visible light different from the wavelength. The light-emitting element is not particularly limited as long as the light from the light-emitting element can be converted into other visible light. For example, a nonlinear optical crystal or the like can be used.

When the light from the light emitting element is high energy short wavelength visible light, a YAG: Ce phosphor or a Ca ₂ Si ₅ N ₈ phosphor, which is a kind of aluminum oxide phosphor, is preferably used. In particular, the YAG: Ce phosphor absorbs part of the blue light from the LED chip depending on its content and emits yellow light that is a complementary color. Can be formed relatively easily. These YAG phosphors and nitride phosphors may be mixed and contained in the sealing member, or may be separately contained in the wavelength conversion member composed of a plurality of layers.

The place for placing the wavelength conversion member 140 is not particularly limited as long as it is on the main light extraction surface side of the light emitting element, and may be provided apart from the light emitting element 110. In addition, by providing the wavelength conversion member 140 so as to cover the light emitting element 110, the light emitting element 110 can be protected from external force, dust, moisture, and the like from the external environment. Further, by making the distance from the outer periphery of the light emitting element 110 to the outer periphery of the wavelength conversion member substantially equal, the light emitting surface can be made smaller and uniform light emission can be obtained. The shape of the wavelength conversion member 140 is not limited to this, and can be various shapes according to the purpose. That is, the lens effect can be achieved by making the wavelength conversion member 140 into a convex lens shape or a concave lens shape. Therefore, as desired, various shapes such as a dome shape, an elliptical shape as viewed from the light emission observation surface side, a cube, and a triangular prism can be selected.

  Epoxy resin, acrylic resin, imide resin, silicone resin, and other organic materials such as glass resin, which are excellent in light resistance and translucency, as a binder material for fixing wavelength conversion members to each other or fixing the wavelength conversion member to the surface of a light emitting element Examples include inorganic substances. In particular, by using an inorganic binder material, all members of the light emitting device can be made of an inorganic material, and a highly reliable high output type light emitting device can be obtained. Further, for the purpose of diffusing light from the light emitting element 110, aluminum oxide, barium oxide, barium titanate, silicon oxide, or the like can be contained. Similarly, various colorants can be added in order to have a filter effect for cutting extraneous light and unnecessary wavelengths from the light emitting element 110. Furthermore, various fillers that relieve internal stress of the sealing resin can be contained.

Moreover, it is preferable that the thickness of the wavelength conversion member is substantially equal from the other outer surface excluding the mounting surface of the light emitting element. Thereby, uniform light emission can be obtained in all directions of the light emitting element. Further, the distance between the mounting surface of the light emitting element and the inorganic member is preferably shorter than the thickness of the wavelength converting member from the other surface of the light emitting element, and thereby the wavelength conversion for sealing the light emitting element. Even when a resin that easily expands thermally is used as the member, it is possible to suppress the flow between the mounting surface of the light emitting element and the inorganic member. In addition, as shown in FIG. 3, it is preferable that the mounting surface side of the light emitting element is an air layer 160. In the case of the air layer, the fluidity is much better than that of the resin, so not only can the volume increase due to thermal expansion be easily escaped, but the generated stress is uniformly applied to the entire surface in contact with the air layer, Since concentration of stress that causes cracks on the members and their interfaces is unlikely to occur, a highly reliable light-emitting device can be obtained.

[Inorganic member 150]
In the light-emitting device of the present invention, an insulating and non-transparent inorganic member 150 is formed on the surface of the translucent heat radiating member 130 at least in the non-conductor wiring formation region on the surface facing the light-emitting element. The inorganic member 150 may extend to the interface between the translucent heat radiating member 130 and the conductor wiring pattern 131. As described above, by forming the conductive wiring pattern 131 after forming the inorganic member 150 on the surface of the light transmissive heat radiating member 130, the process can be simplified. It is also possible to create a method by masking the conductor wiring pattern portion after forming the conductor wiring pattern 130 and forming the inorganic member 150 between the patterns of the conductor wiring pattern. The inorganic member 150 is formed by a method in which the inorganic member 150 is preliminarily formed by paste printing when firing the translucent heat radiating member, or by sputtering deposition, plating or electrodeposition after the translucent heat radiating member is fired. There is a method of forming the inorganic member 150 on the surface by such a method. A material for forming the inorganic member 150 is not particularly limited, but Ni ₂ O ₃ , SiC, C ₃ N ₄ , Ta ₂ O ₅ , SiO ₂ , SiN, AlN, Al ₂ O ₃ , ZrO ₂ , ZnO, TiO ₂ , It is preferable to use at least one selected from Y ₂ O ₃ and Si ₃ N ₄ . Further, by adding C or a transition metal to these materials, the light blocking rate can be improved. In addition, it is possible to improve the light blocking rate by replacing part of the nitride with an oxide. The inorganic member is preferably formed in a film shape, and more preferably a multilayer film. By using a multilayer film, light blocking and insulation can be performed in different layers, and the range of material selection is widened. As the light blocking layer in the multilayer film, it is preferable to use at least one selected from Fe, Ti, Ni, Cu, Zn, Mo, W, Nb, Pd, Ag, W, Pt, and Au. Selected from Ni ₂ O ₃ , SiC, C ₃ N ₄ , Ta ₂ O ₅ , SiO ₂ , SiN, AlN, Al ₂ O ₃ , ZrO ₂ , ZnO, TiO ₂ , Y ₂ O ₃ and Si ₃ N ₄ It is preferable to use at least one kind. In this case, it is possible to achieve both light shielding and insulation by providing an insulating layer by the same method on the surface of a layer having a high light shielding rate prepared by a technique such as plating, sputtering, vapor deposition, electrodeposition or the like.

  Examples according to the present invention will be described in detail below. Needless to say, the present invention is not limited to the following examples.

<Example 1>
As Example 1, the light emitting device shown in FIG. 1 is manufactured.
(First step)

  FIG. 1 is a schematic cross-sectional view of a light emitting device in this example. In the light emitting device in this embodiment, two semiconductor light emitting elements are flip-chip mounted on the same light transmissive heat radiating member (referred to as “submount” in this embodiment) and covered with a wavelength conversion member. Being done.

  After the AlN powder is fired, polishing is performed to form a light transmissive heat radiating member 130. Next, a Ti layer having a thickness of 1 μm is formed by sputtering as the inorganic member 150 on the entire surface of the translucent heat radiating member 130 on the light emitting element mounting side, and then an AlN layer having a thickness of 3 μm is formed by sputtering. Next, a photoresist pattern is formed in a region where no conductor wiring is formed on the surface on which the inorganic member 150 is formed, and an Ag conductor wiring pattern 131 is formed by sputtering.

The light emitting element 110 is made of a nitride-based semiconductor that emits blue light, has two pairs of positive and negative electrodes on the same surface side, and is adjusted in height so that the surfaces are substantially parallel to each other. A light emitting diode is used.

A conductive member is formed on the electrode formation surface side of the light emitting element 110. Specifically, an Au-Sn film separated into three so as to have a substantially elliptical shape in plan view is formed on each positive electrode surface, and an elliptical Au-Sn film not separated on each negative electrode surface. A mask having an opening pattern is placed so that it can be formed, and an Au—Sn film is formed by sputtering with a thickness of 2 μm.

Next, a flux is applied on the conductor wiring patterns 131a and 131b. Here, it is preferable that the flux is applied thicker than the conductive film. The electrodes 111a and 111b of the light emitting element 110 are made to face each other on the conductor wiring pattern 131 on which the flux is formed in this manner, and the Au—Sn film formed on these surfaces is buried in the flux and temporarily fixed.

The translucent heat radiating member 130 on which the light emitting element 110 is temporarily fixed is passed through a reflow furnace at 340 ° C. to melt the surfaces of the Au—Sn films 120a and 120b, and melt bonded to the surfaces of the conductor wiring patterns 130a and 130b, respectively. . The bonding area between the positive electrode 111a and the conductive film 130a is preferably larger than the bonding area between the conductive film 130a and the wiring pattern 120a. As a result, stable bonding can be obtained, and even if the distance between these distances is shortened, sufficient bonding strength and stable conductivity without leakage or opening can be obtained. Further, in the light emitting device, even if a member such as a resin that expands due to thermal stress is interposed between the light emitting element 110 and the light transmissive heat radiating member 130, the light transmissive heat radiating member instantly receives the thermal stress of the inclusion. Since it can escape to 130 side, the light-emitting device which has the outstanding reliability which is not influenced by the use environment can be provided.

Thereafter, the flux is washed with a semi-aqueous detergent.

Next, as a material for the wavelength conversion member, a silicone resin having a center particle diameter of 8 μm (Y _0.995 Gd _0.005 ) _2.750 Al ₅ O ₁₂ : Ce _0.250 containing 20 wt% of a fluorescent substance is used. The wavelength conversion member is formed by screen printing on the main light extraction surface side and the side surface of the light emitting element 110.

  The light emitting device thus obtained can emit light with less color unevenness over the entire light emitting surface without generating a blue ring, and can maintain excellent performance even when a large current is applied.

  The light emitting device according to the present invention does not deteriorate in function due to thermal deformation of the sealing member, and can be used as a highly reliable semiconductor device for a vehicular lamp that requires high output and highly reliable light emission.

FIG. 1 is a schematic cross-sectional view showing a light emitting device according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing a light emitting device according to another embodiment of the present invention. FIG. 3 is a schematic cross-sectional view showing a light emitting device according to another embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Light-emitting device 110 ... Light-emitting element 111a ... Positive electrode 111b ... Negative electrode 120a, 120b ... Conductive member 130 ... Translucent heat radiation member 131a, 131b ... Conductor wiring 140 ... Wavelength conversion member 150 ... Inorganic member 160 ... Air layer

Claims (6)

A translucent heat radiating member; conductor wiring patterned on the surface of the translucent heat radiating member; a light emitting element flip-chip mounted on the conductor wiring; and a wavelength conversion member covering the light emitting element. And
The translucent heat radiating member is formed with an insulating and non- translucent inorganic member in a non-conductor wiring forming region on a surface facing the light emitting element, and the inorganic member is formed with the translucent heat radiating member. A light emitting device characterized by extending to an interface with the conductor wiring .   The light emitting device according to claim 1, wherein the inorganic member extends to an interface between the translucent member and the conductor wiring.   The light-emitting device according to claim 1, wherein a distance between the mounting surface of the light-emitting element and the inorganic member is shorter than a thickness of the wavelength conversion member from the other surface of the light-emitting element. The inorganic member includes Ni ₂ O ₃ , SiC, C ₃ N ₄ , Ta ₂ O ₅ , SiO ₂ , SiN, AlN, Al ₂ O ₃ , ZrO ₂ , ZnO, TiO ₂ , Y ₂ O ₃ and Si ₃ N. The light-emitting device according to claim 1, wherein the light-emitting device is at least one selected from _four .   The light emitting device according to claim 1, wherein the inorganic member is a multilayer film.   The light emitting device according to claim 5, wherein the multilayer film includes a light blocking layer and an insulating layer.

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