JP6592886B2 - Method for manufacturing light emitting device - Google Patents

Description

  The present invention relates to a light emitting device and a method for manufacturing the same.

  In recent years, various lighting devices and the like using semiconductor light emitting elements (hereinafter also simply referred to as light emitting elements) have been developed, and the demand for high reliability is increasing. In order to increase resistance to abnormal current and abnormal voltage, which is one of high reliability, a light emitting device in which a protective element is provided in a light emitting device together with a light emitting element has been proposed. By providing the protective element, it is possible to prevent the light emitting element from being destroyed due to a large overvoltage, surge current, or the like.

For example, in Patent Document 1, the electrodes of the light emitting element and the protective element are electrically connected to the support by contact or a conductive adhesive without using a wire such as a gold wire, thereby preventing an abnormal current or an abnormal voltage. A light emitting device that is difficult to destroy is described.

JP-A-11-54801

  In the light emitting device described in Patent Document 1, the protection element absorbs light from the light emitting element, which causes a problem in that the output is reduced.

An object of this invention is to provide the light-emitting device which can suppress the light absorption by a protection element.

The light-emitting device of the present invention includes a support having conductor wiring, a light-emitting element placed on the support, and at least a part of the substrate placed on the support, and is thicker than the light-emitting element. And a thin protective element.
Alternatively, the light-emitting device includes a support body having conductor wiring, a light-emitting element placed on the support body, and a protection element placed on the support body, and both the light-emitting element and the protection element are substrates. At least a portion of is removed.

  ADVANTAGE OF THE INVENTION According to this invention, the light-emitting device which can suppress the light absorption by a protection element can be provided.

1 is a schematic diagram of a light emitting device according to Embodiment 1. FIG. 1A is a schematic plan view of a light emitting device 100 according to Embodiment 1. FIG. (B) It is a schematic side view of the light-emitting device 100. (C) It is a schematic side view before the board | substrate removal of the protection element 30 of the light-emitting device 100. FIG. 6 is a schematic diagram illustrating a method for manufacturing the light emitting device according to Embodiment 1. FIG. 1A is a schematic plan view of a light emitting device 100. FIG. (B) It is a schematic sectional drawing in the AA cross section after a support body preparation process. (C) It is a schematic sectional drawing in the AA cross section after a light emitting element and a protection element mounting process. (D) It is a schematic sectional drawing in the AA cross section after the board | substrate removal process of a protective element. 6 is a schematic diagram of a light emitting device according to Embodiment 2. FIG. (A) It is a schematic plan view of the light-emitting device 200. (B) It is a schematic sectional drawing in the BB cross section of the light-emitting device 200. FIG. (C) It is a schematic sectional drawing in the BB cross section before the board | substrate removal of the protective element 30 of the light-emitting device 200. FIG. FIG. 6 is a schematic diagram of a light emitting device 300 according to Embodiment 3. (A) It is a schematic plan view of the light-emitting device 300. (B) It is a schematic sectional drawing in the CC cross section of the light-emitting device 300. FIG. 6 is a schematic diagram of a light emitting device according to Embodiment 4. FIG. (A) It is a schematic plan view of the light-emitting device 400. FIG. (B) It is a schematic sectional drawing in the DD cross section of the light-emitting device 400. FIG.

  In the present application, the size and positional relationship of members shown in each drawing may be exaggerated for clarity of explanation. In the following description, the same name and reference numeral indicate the same or similar members, and detailed description thereof will be omitted as appropriate. The contents described in one example and one embodiment can be used in other examples and embodiments.

  The light emitting device according to Embodiment 1 includes a support, a light emitting element, and a protective element. The light emitting device may be either a side view type or a top view type, and is particularly preferably a top view type light emitting device.

  Hereinafter, embodiments will be described with reference to the drawings. Each drawing is a schematic diagram, and the arrangement, dimensions, ratio, shape, and the like shown therein may be different from actual ones.

<Embodiment 1>
FIG. 1A is a schematic plan view of the light emitting device 100 according to the first embodiment. FIG. 1B is a schematic side view of the light emitting device 100. FIG. 1C is a schematic side view of the protective element 30 of the light emitting device 100 before the substrate is removed.
The light emitting device 100 according to the present embodiment includes a support body 10 on which conductor wirings 40a and 40b are arranged, and a light emitting element 20 and a protection element 30 placed so as to be electrically connected to the support body 10. The protective element 30 is made thinner than the light emitting element 20 by removing a part of the substrate.

  Since a part of the substrate of the protection element 30 is removed, the volume of the protection element 30 is smaller than before the removal of the substrate. Thereby, the light emitted in the lateral direction from the light emitting element 20 can be suppressed from being absorbed by the protection element 30.

  Further, since the protective element 30 is thinner than the light emitting element 20, the influence on the light distribution characteristics is also reduced.

  In addition, since the light emitting element 20 and the protection element 30 can be placed on the same plane of the support 10, a thin light emitting device can be manufactured.

  Hereinafter, constituent materials of the light emitting device will be described in detail.

(Support 10)
The light emitting device includes a support for mounting the light emitting element.
The support is usually formed of an insulating material such as glass epoxy, resin, ceramics (HTCC, LTCC), a composite material of an insulating material and a metal member, or the like. The support preferably uses ceramics or thermosetting resin with high heat resistance and weather resistance. Examples of the ceramic material include alumina, aluminum nitride, and mullite. For example, a support formed by combining these ceramic materials with an insulating material such as BT resin, glass epoxy, or epoxy resin may be used. As the thermosetting resin, epoxy resin, triazine derivative epoxy resin, modified epoxy resin, silicone resin, modified silicone resin, acrylate resin, urethane resin, unsaturated polyester, and the like can be used. Among these, it is more preferable to use a triazine derivative epoxy resin.

  The shape of the support is not particularly limited, and any of those having a flat plate, a concavo-convex portion, a reflector having a reflector for efficiently extracting light emitted in the lateral direction from the light emitting element, etc. Good. If it is desired to further reduce the light absorption of the protective element, as shown in FIG. 3 (a is a plan view, b is a cross-sectional view, and c is a cross-sectional view before removing the substrate of the protective element), which is a second embodiment described later. It has a 1st main surface which mounts a light emitting element, and a 2nd main surface which mounts a protection element, and it is preferable that a 1st main surface is located above a 2nd main surface. Thereby, the light emitted from the light emitting element in the lateral direction can be suppressed from being absorbed by the protective element. Further, since the thickness of the protective element is thin enough to remove the substrate, the light emitted from the light emitting element in the lateral direction is applied to the side surface of the protective element even if the height difference between the first main surface and the second main surface is small. You can avoid hitting.

(Conductor wiring 40a, 40b)
A support body has the conductor wiring connected with a light emitting element on the surface and / or inside. Examples of the conductor wiring include a wiring pattern and a lead frame arranged on a support. The wiring pattern can be formed of a metal such as copper, aluminum, gold, silver, tungsten, iron or nickel, or an alloy such as iron-nickel alloy or phosphor bronze. In addition, when the wiring pattern is arranged on the surface, the surface is covered with a highly reflective material such as silver or gold in order to efficiently extract light from the light emitting element to be placed. preferable. Further, the wiring pattern may be bent or deformed on the surface of the support or inside thereof. As for the thickness of a wiring pattern, 1 micrometer-500 micrometers are mentioned, for example.

  The lead frame can be formed of, for example, aluminum, iron, nickel, copper, copper alloy, stainless steel, invar alloy, or the like. A clad material clad with a dissimilar metal may be used. These lead frames are preferably plated with gold, silver, nickel, palladium, or an alloy thereof. As for the thickness of a lead frame, 10 micrometers-1000 micrometers are mentioned, for example.

  Note that the conductor wiring is used not only for electrically connecting the light emitting element and the protective element but also for providing other functions such as mounting the light emitting element or the protective element and improving heat dissipation. can do. Therefore, the support may have not only a pair of positive and negative conductor wires but also a plurality of positive electrode side wires and negative electrode side wires.

(Light emitting element 20)
The light emitting element used in this embodiment means an element called a so-called light emitting diode. Among them, a laminated structure including a light emitting layer of various semiconductors such as nitride semiconductors such as InN, AlN, GaN, InGaN, AlGaN, InGaAlN, III-V group compound semiconductors, II-VI group compound semiconductors on the substrate. What was formed is mentioned. In order to make the light emitting device thinner, it is preferable to remove at least a part of the substrate of the light emitting element as shown in FIG. Thereby, since the thickness of both a light emitting element and a protection element becomes thin, a light emitting device can be made still thinner. In this case, the thickness of the light emitting element may be smaller than the thickness of the protective element. However, light absorption by the protection element is suppressed as compared with the case where the protection element from which the substrate is not removed is placed.

The light emitting element may be one in which positive and negative electrodes are formed on opposite surfaces, and both positive and negative electrodes may be formed on the same surface side. One positive electrode and one negative electrode may be formed, or two or more of each may be formed.

  The electrode is not particularly limited in its material, film thickness, and structure, and may be either a single layer structure or a laminated structure containing gold, copper, lead, aluminum, or an alloy thereof. Further, a single layer film or a multilayer film of a metal or an alloy such as Ni, Ti, Au, Pt, Pd, or W may be formed on the surface of each electrode as a pad electrode. Although the film thickness of an electrode is not specifically limited, It is preferable that Au is arrange | positioned at the last layer (most surface side) especially, and the film thickness is about 100 nm or more.

  When a light emitting element having positive and negative electrodes on the same surface side is used, either face-up mounting or flip chip mounting may be used, but flip chip mounting is preferable. In this case, since a wire bond is not required or the substrate of the light emitting element can be removed by a laser lift-off method or the like, a thinner light emitting device can be obtained.

When using light-emitting elements with positive and negative electrodes on opposite surfaces, the surface on which one electrode is formed is placed on the conductor wiring of the support, and the other electrode is opposite in polarity to the support via the wire. It is electrically connected to the conductor wiring.
There are a growth substrate and a bonding substrate as the substrate of the light-emitting element, and it is preferable to use the growth substrate because it can be manufactured at low cost. The growth substrate is a substrate that becomes a base when a semiconductor layer is grown. The bonding substrate is another substrate to which a semiconductor layer separated from the growth substrate is bonded after the semiconductor layer is grown on the growth substrate.
Although the thickness of a light emitting element is not specifically limited, It is preferable to use the thing of 10 micrometers-1000 micrometers, and 10 micrometers-500 micrometers are especially preferable from a viewpoint of thickness reduction. The thickness of the light emitting element is the total thickness of the semiconductor layer and the substrate, and does not include an electrode portion formed on the light emitting element.

  In the light emitting device of this embodiment, only one light emitting element is placed in one light emitting device, but a plurality of light emitting elements may be placed. When a plurality of light emitting elements are mounted, the connection form is not particularly limited, such as parallel, series, or a combination thereof. By mounting a plurality of light emitting areas, the light emitting area can be increased, and the luminous flux can be improved.

(Protective element 30)
The protection element of this embodiment is electrically connected in antiparallel with the light emitting element, and at least a part of the substrate is removed. The substrate of the protective element includes a growth substrate and a bonding substrate, similarly to the substrate of the light emitting element. The growth substrate is a substrate that becomes a base when a semiconductor layer is manufactured. For example, when GaN is epitaxially grown on sapphire, sapphire is the growth substrate. If a pn junction is formed in silicon by thermal diffusion or ion implantation, silicon is the growth substrate. Similarly to the light emitting element, another substrate to which the semiconductor layer separated from the growth substrate is attached after the growth of the semiconductor layer on the growth substrate is a bonding substrate.

The protective element is not particularly limited, and any protective element may be used as long as it has a substrate. When the positive and negative electrodes are provided on the same surface side, it is preferable that the chip is flip-chip mounted like the light emitting element. In this case, it becomes easy to remove the substrate of the protective element by a laser lift-off method, a chemical lift-off method, or the like. However, the method for removing the substrate is not particularly limited, and any method may be used as long as at least a part of the substrate can be removed, such as polishing or a laser lift-off method. In the case of a protective element in which positive and negative electrodes are formed on opposite surfaces, the electrode is formed after removing the substrate and electrically connected via a wire in the same manner as the light emitting element. Further, since the light absorption can be suppressed as the volume of the protective element becomes smaller, it is preferable that the substrate is completely removed. The removal of the substrate here means removing the protective element after mounting on the support, and does not include polishing of the substrate before mounting.

For example, when the protective element is a nitride semiconductor formed on sapphire, the thickness of the protective element is about 10 to 230 μm. The thickness of the protective element is the sum of the thickness of the semiconductor layer and the thickness of the substrate, and does not include an electrode formed on the protective element. The thickness of the semiconductor layer is usually about 1 to 30 μm. When the thickness of the substrate is, for example, 50 to 200 μm, the thickness of the protective element can be reduced to about 1/10 by removing the substrate. Thereby, the light absorption of the light emitting element by a protective element can be suppressed.

Note that the protective element here is to prevent destruction of the light emitting element from a large overvoltage, surge current, or the like. Specifically, overheating, overvoltage, overcurrent, a protection circuit, an electrostatic protection element, etc. are mentioned. One protective element may be mounted, or two or more protective elements may be mounted.

(Light reflecting member 50)
The protective element may optionally be embedded with a light reflecting member. When the light reflecting member covers the protective element, the light from the light emitting element can be prevented from being absorbed by the protective element. Any method such as coating, printing, or electrodeposition may be used as the method of embedding.
The light reflecting member only needs to cover at least a part of the protective element. Since the protective element of the present embodiment is thin as the substrate is removed, the protective element can be embedded with a small amount of light reflecting member as compared with the case where the protective element from which the substrate is not removed is coated. In addition, since the height of the light reflecting member is lower by the substrate of the protective element than when the protective element from which the substrate is not removed is embedded, the influence on the light distribution characteristics can be reduced.

The light reflecting member is preferably made of a reflective material having a reflectance of 60% or more with respect to light from the light emitting element, and further made of a reflective material of 70%, 80%, or 90% or more.
The reflective material can be formed of, for example, ceramic, resin, dielectric, pulp, glass, or a composite material thereof. Among these, a resin is preferable from the viewpoint that it can be easily formed into an arbitrary shape.

Examples of the resin include a thermosetting resin and a thermoplastic resin. Specifically, a silicone resin, a modified silicone resin, an epoxy resin, a modified epoxy resin, a resin containing one or more of an acrylic resin, a hybrid resin, or the like can be given.

In addition, these materials, for example, resin, titanium dioxide, silicon dioxide, zirconium dioxide, potassium titanate, alumina, aluminum nitride, boron nitride, mullite, niobium oxide, zinc oxide, barium sulfate, various rare earth oxides (for example, oxidation) It is preferable to contain a light reflecting member such as yttrium or gadolinium), a light scattering material, or a colorant. Glass fibers, fibrous fillers such as wollastonite, inorganic fillers such as carbon black, and materials with high heat dissipation (for example, aluminum nitride) may be included. These light reflecting members and the like can be contained at about 5 to 60% with respect to the total weight of the light transmitting layer, for example.

(Translucent layer 60)
The light emitting element and the protective element may be optionally covered with a light transmitting layer. The light transmissive layer is a layer that allows light emitted from the light emitting element to pass through, and transmits 60% or more of light emitted from the light emitting element, and further transmits 70%, 80%, or 90% or more. Is preferred. Such a layer is, for example, a resin such as a silicone resin, a silicone modified resin, an epoxy resin, a phenol resin, a polycarbonate resin, an acrylic resin, a trimethylpentene resin, a polynorbornene resin, or a hybrid resin containing one or more of these resins, or It can be formed of glass or the like. In addition, when the light transmitting layer has a lens function, the surface of the light transmitting layer may be raised so as to have a shell shape or a convex lens shape.

The light-transmitting layer may contain a phosphor or a diffusing material.
(Phosphor)
As the phosphor, those known in the art can be used. For example, yttrium-aluminum-garnet (YAG) phosphors activated with cerium, lutetium-aluminum-garnet (LAG) activated with cerium, nitrogen-containing calcium aluminosilicate (CaO- activated with europium and / or chromium) Al ₂ O ₃ —SiO ₂ ) -based phosphor, europium-activated silicate ((Sr, Ba) ₂ SiO ₄ ) -based phosphor, β-sialon phosphor, CASN-based and SCASN-based phosphors Body, KSF phosphor (K ₂ SiF ₆ : Mn), sulfide phosphor and the like. When the light emitting device is used for a backlight of a liquid crystal display or the like, a phosphor that is excited by blue light and emits red light (for example, KSF phosphor) and a phosphor that emits green light (for example, β sialon phosphor) are used. It is preferable. Thereby, the color reproduction range of the display using a light-emitting device can be expanded. Moreover, when used for illumination etc., the element which light-emits blue-green, and a red fluorescent substance can be used in combination.

For example, the phosphor preferably has a center particle size of 50 μm or less. The central particle size can be measured and calculated by a commercially available particle measuring device or particle size distribution measuring device. In particular, when YAG or the like is used as the phosphor, a bulk body (for example, a plate-like body) in which these ultrafine particles are dispersed and sintered extremely uniformly is preferable. With such a form, a high degree of transparency can be ensured by reducing voids and impurity layers as a single crystal structure and / or a polycrystalline structure.

The phosphor may be, for example, a so-called nanocrystal or a light-emitting substance called a quantum dot. These materials include semiconductor materials such as II-VI group, III-V group, and IV-VI group semiconductors, specifically, CdSe, core-shell type CdS _x Se _1-x / ZnS, GaP, etc. Examples include highly dispersed particles of size. Examples of such a phosphor include a particle size of about 1 to 20 nm (10 to 50 atoms). By using such a phosphor, internal scattering can be suppressed and the light transmittance can be further improved. Since the quantum dot phosphor is unstable, it may be surface modified or stabilized with a resin such as PMMA (polymethyl methacrylate). These may be a bulk body (for example, a plate-like body) mixed and molded with a transparent resin (for example, an epoxy resin, a silicone resin, etc.), or a plate-like body sealed with a transparent resin between glass plates. May be.

(Production method)
A method for manufacturing the light emitting device 100 of this embodiment will be described with reference to FIG.

(Preparation of support)
First, as shown in FIG. 2B, a support 10 having a pair of positive and negative conductor wirings 40a and 40b on a support is prepared. The conductor wirings 40a and 40b can be formed by a known method on the surface of the support or inside the support by a known method.
(Light emitting element and protective element mounting process)
Next, as shown in FIG. 2C, the light emitting element 20 and the protection element 30 are placed on the conductor wirings 40a and 40b and electrically connected thereto. At this time, the light emitting element 20 and the protection element 30 are electrically connected in antiparallel. Mounting methods include face-up mounting and flip-chip mounting. As shown in FIG. 2C, flip-chip mounting of both the light emitting element 20 and the protective element 30 is preferable because electrical connection can be established with the conductor wirings 40a and 40b.
(Protection element substrate removal process)
Subsequently, the substrate of the protection element 30 is removed as shown in FIG. The removal method includes polishing, laser lift-off method, chemical lift-off method and the like. When flip chip mounting is performed at the time of mounting, the substrate of the protective element can be removed by a laser lift-off method or a chemical lift-off method. Since the volume of the protective element 30 is reduced by the removing step, light absorption from the light emitting element can be suppressed.
(Process of embedding protective element with light reflecting member)
After the removing step, the protective element 30 may be embedded with the light reflecting member 50 as shown in FIG. Embedding methods include coating, printing, and electrodeposition. For example, in the case of application or printing, the light reflecting member 50 is preferably embedded with resin. The protection element 30 may be embedded by applying the light reflection member 50 using a nozzle, or the protection element 30 may be embedded by printing the light reflection member 50 using a mask having an opening at the position of the protection element 30. May be. In addition, the protective element 30 may be embedded with the light reflecting member 50 by electrodeposition. Specifically, it can be embedded by disposing the light reflecting member 50 around the protective element 30 using an electrophoresis technique. Moreover, the thickness of the light reflection member 50 can be made uniform by embedding by electrodeposition. The light reflecting member 50 preferably has a high light reflectance such as titanium dioxide, zirconia, or alumina.

(Embodiment 2)
Next, the light emitting device 200 according to Embodiment 2 will be described. Note that a description of the same components as those of the light-emitting device according to Embodiment 1 is omitted. In the second embodiment, as shown in FIG. 3 (a is a plan view, b is a cross-sectional view, and c is a cross-sectional view before removing the substrate of the protective element), the support 10 places the first main element on which the light-emitting element 20 is placed. And a second main surface on which the protection element 30 is placed, and the first main surface is located above the second main surface. Thereby, the light-emitting device 200 which suppressed the light absorption of the protective element 30 more can be provided. Since the same effect can be obtained even if the difference in height between the first main surface and the second main surface is as small as the thickness of the protective element substrate removed, the light emitting device can be made thinner. In addition, in order to suppress lateral light absorption from the light emitting element, the difference in height between the first main surface and the second main surface is preferably equal to or higher than the height of the protection element 30. For this reason, in Embodiment 2, since the board | substrate part thickness of the protective element from which the difference of the height of the 1st main surface and the 2nd main surface was removed is thin, a light-emitting device can be reduced in thickness. Further, the light transmissive layer 60 is optional, and the light emitting element 20 and the protective element 30 may be covered as in the second embodiment.

(Embodiment 3)
A light emitting device 300 according to Embodiment 3 will be described. Note that a description of the same components as those of the light-emitting devices according to Embodiments 1 and 2 is omitted. The third embodiment is characterized in that at least a part of the substrate of the light emitting element 20 is removed as shown in FIG. 4 (a is a plan view and b is a sectional view). Thereby, the light emitting device 300 that can be made thinner can be provided. The mounting method of the light emitting element 20 is preferably flip-chip mounting, and the substrate removal of the light emitting element 20 includes the laser lift-off method, the chemical lift-off method, and the like as the substrate removal of the protection element 30. Since both the light-emitting element and the protective element remove the substrate, the light-emitting element may be thinner than the protective element. However, since the volume of the protective element is smaller by the amount of the removed substrate, light absorption is less than in the case of the protective element in which the conventional substrate is not removed. Further, it is preferable that all of the substrate of the light emitting element is removed in the same manner as the substrate of the protective element.

(Embodiment 4)
A light-emitting device according to Embodiment 4 will be described. In addition, description is abbreviate | omitted about the structure which overlaps with the light-emitting device which concerns on Embodiment 1-3. In the fourth embodiment, as shown in FIG. 5 (a is a plan view and b is a cross-sectional view), the protective element 30 is embedded in a light reflecting member 50. Thereby, the light-emitting device 400 which suppressed the light absorption by the protective element 30 more can be provided. Comparing the fourth embodiment and the case where the protective element 30 from which the substrate is not removed is embedded with the light reflecting member 50, the thickness is reduced by the amount of the substrate, so that the influence on the light distribution characteristics is reduced or the protection is performed. The number of light reflecting members 50 necessary for embedding the element 30 may be reduced. As a method of embedding the protective element 30, a known method such as coating, printing, electrodeposition can be used.

  The light emitting device according to the present embodiment includes a backlight device for a liquid crystal display, various lighting fixtures, a large display, various display devices such as advertisements and destination guides, a projector device, a digital video camera, a facsimile, a copier, a scanner, and the like It can be used for an image reading apparatus and the like.

DESCRIPTION OF SYMBOLS 10 ... Support body 20 ... Light emitting element 30 ... Protection element 40a, 40b ... Conductor wiring 50 ... Light reflection member 60 ... Translucent layer 100,200,300,400 ... Light emitting device

Claims (5)

Preparing a support body having conductor wiring , a first main surface, and a second main surface located below the first main surface ;
Flip chip mounting a light emitting element on the first main surface of the support, and flip chip mounting a protection element having a substrate on the second main surface;
A removing step of removing at least a part of the substrate of the protective element;
Have a in this order,
In the flip chip mounting step, the upper surface of the protection element including the substrate is located above the first main surface,
The upper surface of the protective element from which at least a part of the substrate after the removing step is removed is located below the first main surface,
The method for manufacturing a light emitting device, wherein the protective element after the removing step is thinner than the thickness of the light emitting element .   The method for manufacturing a light emitting device according to claim 1, wherein the method for manufacturing the light emitting device includes a step of applying a light reflecting member to the protection element after the removing step.   The method for manufacturing a light emitting device according to claim 1, further comprising a step of printing a light reflecting member on the protection element after the removing step.   The method for manufacturing a light emitting device according to claim 1, further comprising a step of electrodepositing a light reflecting member on the protection element after the removing step.   The method for manufacturing a light emitting device according to claim 1, wherein the removing step uses a laser lift-off method.

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