JP2013065641A - Light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting element and a light-emitting device with little color unevenness.SOLUTION: The light-emitting element with a cover member according to the present invention includes: a light-emitting element provided with a semiconductor layer having a light-emitting layer; and a cover member on the light-emitting element, which contains a wavelength conversion member for converting light from the light-emitting layer. The light-emitting element with a cover member is characterized in that: the light-emitting element has a reflection member on a lower surface of the semiconductor layer; and an edge of the cover member is positioned below a side surface of the light-emitting layer and above a lower surface of the light-emitting element.

Description

  The present invention relates to a light-emitting element that can be used in a lighting device and the like and a light-emitting device using the same, and more particularly, to a light-emitting element with a covering member and a light-emitting device using the light-emitting element.

  In general, a light emitting device such as a light emitting diode (LED) is made up of an electronic component such as a light emitting element or a protective element having a semiconductor layer, a substrate on which they are disposed, and a translucent resin for protecting the light emitting element or the protective element. It consists of.

  Light-emitting devices used for general lighting are most widely used as white light, such as daylight white or light bulb color, but semiconductor layers that can emit white light are now in practical use. However, there is used a technique for obtaining white light as mixed color light combining multiple colors. As such a light emitting device using mixed color light, a concave portion is provided in a base, a light emitting element emitting blue light is disposed in the concave portion, and a phosphor is contained so as to cover the light emitting element in the concave portion. It is known to provide a translucent resin. In such a light emitting device, a part of blue light output from the light emitting element is wavelength-converted by a phosphor, and color mixing of the wavelength converted yellow light and blue light from the light emitting element is performed. Thus, white light is emitted.

  However, the light emitting device having a structure in which the phosphor is contained in the entire recess as described above has a different distance, that is, an optical path length, until the light from the light emitting element reaches the phosphor. Therefore, a difference occurs in the amount of blue light absorbed by the phosphor, and it is difficult to obtain uniform white light. If the volume of the concave portion is reduced, it is possible to reduce the optical path length difference, but when considering the accuracy when mounting the light emitting element, and securing the bonding area when bonding the conductive wire after mounting, There is a limit to making the recess small.

  In addition, it is known that a lens is provided on the upper surface of the light emitting element and phosphor is contained in the lens instead of providing the entire light transmitting resin in the recess (for example, Patent Document 1). By doing in this way, the difference of optical path length can be made small compared with the case where fluorescent substance is contained in the whole recessed part.

JP 2006-324408 A

  However, in Patent Document 1, since flip chip mounting is performed, the sapphire substrate is on the upper surface, and since the lens is formed on the sapphire substrate, light is emitted from the side surface of the sapphire substrate. That is, blue light is emitted from the side surface instead of the mixed color light, and the color unevenness of the light emitting device increases.

  In order to solve the above problems, a light-emitting element with a covering member according to the present invention includes a light-emitting element including a semiconductor layer having a light-emitting layer, and a wavelength conversion member that converts light from the light-emitting layer on the light-emitting element. A light-emitting element with a covering member, wherein the light-emitting element has a reflecting member on a lower surface of the semiconductor layer, and the edge of the covering member is below the side surface of the light-emitting layer. And it is located above the lower surface of a light emitting element, It is characterized by the above-mentioned. Thereby, color unevenness can be reduced.

  With the structure of the present invention, a light-emitting element and a light-emitting device capable of obtaining uniform light emission can be obtained.

FIG. 1A is a cross-sectional view showing a light-emitting element with a covering member according to an embodiment of the present invention. It is a top view of the light emitting element in the light emitting element with a covering member shown to FIG. 1B and FIG. 1A. 2 is a cross-sectional view of a light-emitting device using the light-emitting element with a covering member shown in FIG. 1A. FIG. 3 is a cross-sectional view showing a light-emitting element with a covering member according to an embodiment of the present invention. FIG. 4 is a cross-sectional view showing a light emitting element with a covering member according to an embodiment of the present invention.

  A mode for carrying out the present invention will be described below with reference to the drawings. However, the form shown below illustrates the light emitting element with a covering member and the light emitting device for embodying the technical idea of the present invention, and is not limited to the following. In addition, 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 specific examples unless otherwise specified. Only. It should be noted that the size and positional relationship of the members shown in each drawing may be exaggerated for clarity of explanation.

  1A shows a cross-sectional view of a light-emitting element with a covering member in the present embodiment, and FIG. 1B shows a top view of only the light-emitting element part of FIG. 1A. In the present embodiment, the light-emitting element 1 includes a semiconductor layer 11 having a light-emitting layer 11b between an upper layer 11a and a lower layer 11c, and converts light from the light-emitting layer 11b onto the semiconductor layer 11. A covering member 2 containing a wavelength conversion member is provided. The lower surface of the semiconductor layer 11 (lower layer 11 c) has a reflecting member 13, and the covering member 2 has an edge below the side surface of the light emitting layer 11 b and the lower surface of the light emitting element 1. It is provided so as to be located on the upper side. Thereby, it is possible to suppress light from the light emitting layer 11b from being emitted outside through the side surface and the lower surface of the light emitting element 1 without passing through the covering member 2, and color unevenness can be reduced. Furthermore, since the edge of the covering member 2 is provided in the vicinity of the light emitting layer 11b, the difference in the distance (optical path length) between the wavelength conversion member included in the covering member 2 and the light emitting layer 11b can be reduced. Since it can be made smaller, color unevenness can be further reduced, and the emission point of mixed color light can be made smaller.

  Such a light emitting element with a covering member includes a step of growing a semiconductor layer including a light emitting layer on a growth substrate, a step of providing a reflecting member on a surface of the semiconductor layer facing the growth substrate, and a growth substrate. A step of forming a light emitting element from which the semiconductor layer is exposed, and a covering member containing a wavelength conversion member that converts light from the light emitting layer on the exposed semiconductor layer, And a step of providing the light emitting layer so as to be located below the side surface of the light emitting layer and above the lower surface of the light emitting element.

In the present embodiment, the position where the edge of the covering member is provided is the “surface located between the upper surface and the lower surface of the light emitting element”, so that the covering member is limited in the vicinity of the light emitting layer. It is the feature that it is provided in the region, and the orientation of the surface does not indicate only the lateral surface. For example, a case where a step portion (protruding portion) is provided on the side surface of the light emitting element and is provided on the “upper surface of the step portion” is also included in the “side surface of the light emitting element”. In other words, the present invention is characterized in that the edge of the covering member is provided above the lower surface of the light emitting element, and it is important that the edge is provided on the “side surface of the light emitting element” including the stepped portion. It is. With such a configuration, the covering member provided in the light emitting element becomes a limited narrow region in the vicinity of the light emitting element (light emitting layer), so that the difference in optical path length can be reduced and color unevenness can be reduced.
Hereinafter, each member will be described in detail.

<Light emitting element>
The light-emitting element includes a semiconductor layer having a light-emitting layer and a reflecting member provided on the lower surface of the semiconductor layer, and electrodes are provided on the lower layer and the upper layer of the semiconductor layer, respectively. Further, a protective film may be provided on the surface (upper surface, lower surface, side surface) of the semiconductor layer, and a substrate (bonded substrate) for supporting the semiconductor layer may be provided on the lower surface of the reflecting member. .

(Semiconductor layer)
The semiconductor layer has a laminated structure including a light emitting layer that can emit light when energized, and the light emitting layer is provided between an upper layer and a lower layer. The upper layer and the lower layer are composed of layers having different conductivity. For example, when the upper layer is a p-type semiconductor layer, the lower layer is an n-type semiconductor layer, and when the upper layer is an n-type semiconductor layer, the lower layer is a p-type semiconductor. A reflective member is provided on the lower surface of the semiconductor layer which is the lower layer. In this specification, irrespective of the stacking direction of the semiconductor layers, the semiconductor layer on the side where the reflecting member is provided is the lower layer, and the semiconductor layer on the side where the reflecting member is not provided (the side where the covering member is provided) is the upper layer. And

As the semiconductor layer, a semiconductor layer having a composition with an arbitrary wavelength can be selected according to the purpose or the like. For example, the blue, the green semiconductor layer, ZnSe and nitride semiconductor _{(In X Al Y Ga 1-} X-Y N, 0 ≦ X, 0 ≦ Y, X + Y ≦ 1), used after using GaP be able to. As the red semiconductor layer, GaAlAs, AlInGaP, or the like can be used. Furthermore, a semiconductor layer made of a material other than this can also be used. The composition, emission color, size, number, and the like of the semiconductor layer to be used can be appropriately selected according to the purpose.

  The film thickness of the upper layer, the light emitting layer, and the lower layer constituting the semiconductor layer, and the shape and size in the top view are not particularly limited, but the lower layer should be relatively thin so that it can be easily covered with the covering member. Is preferred.

(electrode)
In addition, the semiconductor layer has electrodes 12 in contact with the upper layer and the lower layer, which are an upper electrode and a lower electrode, respectively. Both the upper electrode and the lower electrode can be formed on the upper surface of the semiconductor layer. Conversely, both the upper electrode and the lower electrode can be formed on the lower surface of the semiconductor layer. In FIG. 1A, the upper electrode 121 is provided on the upper surface of the semiconductor layer 11, the lower electrode 122 is provided on the lower surface of the semiconductor layer 11, and the lower electrode is also used as a reflecting member. Yes.

  The upper electrode provided in the upper layer is preferably provided with a pad portion for joining the conductive wires. The pad portion is provided as a cushioning material for reducing the local mechanical load on the semiconductor layer when bonding the conductive wires, and further for improving their bonding strength. The position, number, thickness, and the like of the light emitting element can be variously selected according to the purpose and application, and the size and the like of the light emitting element, thereby optimizing the electric resistance and light emission efficiency of the light emitting element.

  In order to satisfy the above conditions, the pad portion needs to have a certain thickness, and thus is formed with a thickness that does not transmit light from the light emitting layer. Therefore, it is preferable to provide as small an area as possible on the upper surface of the upper layer, and it is sufficient to provide at least an area where the conductive wire can be joined. For example, as shown in FIG. 1B, four pad portions are provided as the upper electrode 121 provided on the upper surface of the light emitting element 1 (semiconductor layer 11). Here, each pad part is composed of a circular joint part and an extending part extending radially from the joint part. The joint portion is a portion to which the conductive wire is joined, and the diameter and shape can be selected depending on the thickness of the conductive wire, and in addition to the circle shown in FIG. 1B, a rectangle, a rectangle, an ellipse, a polygon , And combinations of these can be selected. The extending portion functions as an auxiliary electrode for widely diffusing the current supplied through the conductive wire in the plane of the light emitting element. Here, although four extending | stretching parts are radially extended from each junction part, it is not limited to this, It can form with arbitrary numbers, shapes, and lengths.

  Moreover, you may provide the transparent electrode which conduct | electrically_connects with the pad part to which a conductive wire is joined in the wide range of the upper surface of an upper layer. Examples of the pad portion of the upper electrode include Au, Al, Rh, and Pd. Examples of the transparent electrode include ITO, ZnO, AZO (Aluminium doped Zinc Oxide), and GZO (Gallium doped Zinc Oxide).

  The lower electrode 122 provided in the lower layer may be provided on the exposed surface (upper surface of the lower layer) by exposing the lower layer to the upper side by removing a part of the upper layer and the light emitting layer. Provided on the lower surface of the lower layer and combined with the upper electrode to form upper and lower electrodes. Accordingly, since the light emitting layer can be widely used without removing a part of the light emitting layer, a decrease in light emission efficiency as a light emitting element can be suppressed. Furthermore, since the conductive path also has a function as a heat dissipation path, providing the lower electrode in a wide range of the lower layer is advantageous for thermal conductivity.

  When the lower electrode is provided on the upper surface of the lower layer, the same material as the pad portion of the upper electrode provided in the upper layer can be used, and a conductive wire is connected to the pad portion. Moreover, when providing in the lower surface of a lower layer, since a conductive wire is not connected, it is preferable to provide a lower electrode so that it may cover almost the whole surface, and this lower electrode can also function as a below-mentioned reflecting member. The case where the reflective member is also used will be described later. When not functioning as a reflecting member, it is preferable to be light-transmitting in order to transmit light from the light emitting layer and reflect it by the reflecting member. Examples of such materials include ITO, ZnO, AZO, GZO, and the like. Can be mentioned.

(Conductive wire)
In order to supply power to the light emitting element, a conductive wire 30 is bonded to the electrode of the light emitting element 1 as shown in FIG. Depending on the position of the upper electrode (pad portion) and the loop shape of the conductive wire, the position where the conductive wire protrudes from the covering member and the angle formed between the conductive wire and the surface of the covering member can be changed. Thus, the shape of the covering member can be controlled. Here, “the angle formed by the conductive wire and the surface of the covering member” means that in the cross-sectional view shown in FIG. An angle θ formed with the conductive wire (an angle between a normal line below the conductive wire). Furthermore, in consideration of the characteristics of the material of the covering member, a desired shape can be obtained by combining these parameters.

  For example, as shown in FIG. 1A, when it is desired to form the covering member in a hemispherical shape, the angle θ formed by the conductive wire and the clothing member surface is preferably 45 ° to 90 °, more preferably 70 ° to 90 °. . In addition, the covering member can be formed in a hemispherical shape by arranging the position of the pad portion in the vicinity of the corner of the upper surface of the light emitting element. Further, as shown in FIG. 3, in order to increase the height of the covering member, the angle θ formed by the conductive wire (not shown) and the covering member surface is 45 ° to 90 °. By doing so, the covering member before curing is prevented from flowing in the lateral direction, and the height is easily maintained.

  On the other hand, the covering member may be shaped as shown in FIG. This is because the covering member 2 of FIG. 1A and FIG. 3 mainly becomes a spherical shape (semispherical) due to its large surface tension, whereas the shape of the covering member 2 as shown in FIG. This can be obtained when a covering member having a viscosity that can suppress deformation is used. And it can be set as the light distribution characteristic different from a hemispherical covering member by setting it as the shape protruded so that the vertex of the covering member might be sharp. Depending on the balance of the overall shape, various light distribution characteristics can be obtained. In the case of such a shape, the angle θ formed by the wire (not shown) and the clothing member is suitably 20 ° to 45 °. When the angle formed by the wire and the covering member is less than 20 °, the covering member flows out along the wire surface, and it becomes difficult to cover the light emitting element with a certain amount of the covering member.

  Moreover, when providing a some pad part in this way, it is preferable to make the extending direction of an electroconductive wire into the direction used as point symmetry or line symmetry in the top view of a light emitting element. For example, as shown in FIG. 1B, in the case of having four pad portions, the light emitting element may extend in the radial direction, or it may be symmetrical with respect to the central line including the center of the light emitting element. It may be extended. Furthermore, it is preferable to make these loop shapes equal.

  As the conductive wire, metals such as gold, copper, platinum, and aluminum, and alloys thereof can be used. In particular, it is preferable to use gold excellent in thermal resistance.

(Reflective member)
The reflecting member is a member that is provided on the lower surface of the lower layer of the semiconductor layer and reflects light from the light emitting layer of the semiconductor layer. At least light from the light emitting layer preferably has a reflectance of 70% or more, and more preferably has a reflectance of 80% or more.

  Since a growth substrate for growing a semiconductor layer has a property of transmitting or absorbing light from the light emitting layer, in this embodiment, such a growth substrate is not provided on the lower surface of the lower layer of the semiconductor layer. Instead, a reflecting member is provided. Such a reflecting member can be provided on either the upper surface of the semiconductor layer laminated on the growth substrate or the surface from which the growth substrate is removed, and the semiconductor layer on the side where the reflecting member is provided is defined as the lower layer. To do.

  Since the reflecting member is a member for suppressing light from the light emitting layer from being emitted from the lower surface, the reflecting member is preferably provided below the central region of the light emitting layer in a top view, and further, the lower surface of the lower layer of the semiconductor layer It is preferable to provide in substantially the whole area. The film thickness may be any film thickness that can reflect light from the light emitting layer, and is preferably 0.05 μm to 0.5 μm although it depends on the material.

  In addition, a metal may be used as the reflecting member to function as an electrode for supplying power to the light emitting layer instead of a simple light reflecting member. In that case, a member having excellent conductivity is preferable.

  As the reflecting member, a member having a high reflectance with respect to light from the light emitting layer is preferable on the side in contact with the lower surface of the lower layer of the semiconductor layer, and a metal, a dielectric multilayer film or the like can be used. preferable. Specifically, Ag, Al, Pt, Au, Pd, or the like can be used alone or a plurality of materials such as alloys can be used. In particular, it is preferable to provide Ag.

(Substrate / joining member)
A reflective member is provided under the lower surface of the lower layer of the semiconductor layer, but a substrate may be further provided under the reflective member. The semiconductor layer has a combined thickness of the upper layer, the light emitting layer, and the lower layer, which is as thin as several μm to several hundreds of μm, and requires careful handling. Therefore, the strength can be improved by using a reflective member provided on the lower surface of the lower layer that has a relatively large thickness. However, the reflecting member first needs to have a high reflectance, and it is not always necessary to have all other characteristics such as mechanical strength, heat dissipation, and bonding property with the base (PKG substrate). . Therefore, it may be preferable to supplement these other functions with separate members. For example, a substrate excellent in heat dissipation, a substrate having a small difference in linear expansion coefficient from the semiconductor layer, or the like can be used. In this specification, such a substrate is also referred to as a “bonded substrate”.

  The bonded substrate preferably has an area larger than that of the semiconductor layer when viewed from above. In other words, as shown in FIG. 1A, in a cross-sectional view, the width of the bonded substrate 14 is wider than the width of the semiconductor layer 11, and the side surface of the bonded substrate is more outward than the side surface of the semiconductor layer. It is preferable to make it protrude. Accordingly, it is possible to prevent light from the light emitting layer from leaking from the lower side, and it is possible to provide a stepped portion (projecting portion) 14a on the side surface of the light emitting element. By providing such a stepped portion 14a, it is possible to easily form an edge portion of a covering member, which will be described later, so as to be positioned on the upper surface of the stepped portion.

  Such a stepped portion 14a is preferably provided on the entire side surface (entire periphery) of the light-emitting element, and the protruding amount (the length between the side surface of the bonded substrate 14 and the side surface of the semiconductor layer 11) is on the entire periphery. It is preferable to make them substantially equal. In other words, after the bonded substrate 14 and the semiconductor layer 11 are bonded together, a step portion is formed by etching, and then a covering member is formed.

  Thereafter, the light emitting elements are preferably separated into pieces so that the protruding amount is uniform. Thereby, it becomes easy to form so that the center of a covering member may be located in the center of a semiconductor layer in top view. The protruding amount of the protruding portion 14a (the length (width) of the upper surface of the stepped portion) is not particularly limited, and is adjusted according to the viscosity of the covering member, the target height, the dicing accuracy, the etching accuracy, and the like. can do.

  Such a bonded substrate 14 is preferably a conductive substrate when the reflective member on the lower surface of the semiconductor layer functions as an electrode. In this case, the joining member also needs to be conductive. Specifically, for example, a semiconductor substrate made of a semiconductor such as Si or SiC, a single metal substrate, or a metal substrate made of a composite of two or more metals having a non-solid solution or a small solid solution limit is used. be able to. This is because the metal substrate has superior mechanical characteristics as compared with the semiconductor substrate, is easily elastically deformed, and further plastically deformed, and is difficult to break. Furthermore, the metal substrate has one or more metals selected from highly conductive metals such as Ag, Cu, Au, and Pt, and one type selected from metals having high hardness such as W, Mo, Cr, and Ni. What consists of the above metals can be used. Furthermore, it is preferable to use a Cu—W or Cu—Mo composite as the metal substrate.

  In addition, an insulating substrate can be used in a case where both electrodes are provided on the light extraction surface of the light emitting element. In this case, ceramics such as alumina and aluminum nitride (AlN), glass epoxy resin, thermoplastic resin, and glass can be used.

  When these substrates are bonded to the semiconductor layer, the above-described reflecting member may be used as a bonding member, or a bonding member separate from the reflecting member may be used. As such a joining member, a member excellent in adhesion to both the reflecting member and the substrate is preferable, and a conductive or insulating member can be used. In the case where the reflecting member functions as an electrode of the semiconductor layer and a conductive substrate is interposed, it is preferable to use a conductive bonding member, which enables conduction from the lower surface of the semiconductor layer. Examples of conductive bonding members include solder materials such as Sn-Cu, Sn-Ag-Cu, Sn-Pb, and Au-Sn, conductive pastes such as Ag paste, anisotropic conductive paste, and metal bumps such as Au. , Ag nano paste, Au nano paste, room temperature activated bonding, and the like can be used. Also, when an insulating substrate is used, it is preferable to use the above-described conductive bonding member as a bonding material, although it does not contribute to conduction.

  Further, a back surface metallized layer 14 b may be provided on the lower surface (back surface) of the bonded substrate 14. When the light emitting element 1 including the bonded substrate 14 and the semiconductor layer 11 is mounted on the base body 20 as shown in FIG. 2, it is possible to mount with good adhesion by providing such a back surface metallized layer 14b. . Moreover, heat dissipation can also be improved. As such a back metallization layer, Al, Au or the like can be used.

(Protective film)
A protective film may be provided on the surface (upper surface, lower surface, side surface) of the semiconductor layer in order to protect the semiconductor layer from the outside. When provided on the upper surface, a light-transmitting material is preferable, and when provided on the side surface, a light-transmitting and insulating material is preferable. In the case of being provided on the lower surface, the light-transmitting property is not necessarily required, and both the insulating property and the conductive property can be used depending on the material such as the reflecting member or the substrate.

  In the case where an insulating protective film is provided on the upper and lower surfaces of the semiconductor layer, it is necessary to provide at least portions necessary for conduction of the upper electrode and the lower electrode. In that case, a region where a protective film is provided can be selected in accordance with the shape of each electrode. For example, as shown in FIG. 1A, when the upper electrode 121 is provided on the upper surface of the upper layer and the lower electrode 122 is provided on the lower surface of the lower layer, the upper electrode 121 is partially formed in a relatively narrow area with respect to the area of the semiconductor layer. If the lower electrode is formed immediately below, the current concentrates in that portion, and the difference in emission intensity between the vicinity of the upper electrode and the remote area Tends to be large. Therefore, it is preferable to provide the protective film 15 which is an insulating member without providing the reflective member functioning as an electrode immediately below the upper electrode (pad portion). Thereby, the current can be easily spread in the lateral direction of the semiconductor layer, and the light intensity distribution can be easily made uniform in the plane.

  In addition, the protective film provided on the side surface of the semiconductor layer is continuous over the side surfaces of the upper layer, the light emitting layer, and the lower layer of the semiconductor layer in order to suppress the occurrence of a short circuit due to a conductive deposit or the like. It is preferable to provide it. In the present embodiment, the covering member, which is an insulating material, is continuously formed so as to reach from the upper surface of the semiconductor layer to the side surface of the lower layer, but at least a part of the edge portion emits light from the semiconductor layer. Part of the side surface of the semiconductor layer may be exposed as long as it is provided up to the lower side of the layer. In such a case, it is preferable to provide a protective film on the upper surface of the semiconductor layer, the light emitting layer, and the side surfaces of the lower layer.

  Moreover, the protective film provided on the side surface of the light emitting element can be provided with a function for defining the position of the edge of the covering member in addition to preventing such a short circuit. That is, on one side of the light emitting element, by providing a region where the protective film is provided and a region where the protective film is not provided, a difference in surface wettability is provided, and this difference is used to suppress the spread of the covering member. The position of the edge can be controlled. In addition to controlling the characteristics (thixotropic ratio) of the covering member described later, the position of the edge of the covering member can be adjusted more accurately by controlling the wettability between the covering member and the protective film. it can.

  In order to control the position of such an edge, the protective film is preferably provided on the side surface of the lower layer of the light emitting layer. When the reflective member is provided on the lower surface of the semiconductor layer, the protective film is further bonded to the lower surface. When the substrate is provided, it is preferable not to provide a protective film on the side surfaces thereof, that is, to expose them on the side surfaces. Thus, the side surface of the light emitting element is composed of members having different surface characteristics (wetting properties), such as a semiconductor layer on which a protective film is formed, an exposed reflecting member, and an exposed substrate. And when providing a coating | coated member, the edge part of a coating | coated member becomes easy to stop at the boundary of the different wettability.

  In the case where the bonded substrate is larger than the semiconductor layer, that is, when the above-described protruding portion (stepped portion) is provided, a protective film may be provided on the upper surface of the protruding portion. Thereby, the edge part of a coating | coated member becomes easy to stop at the edge part of the upper surface of a protrusion part.

Such a protective film preferably has a thickness capable of transmitting light from the light emitting layer, and needs to have a thickness sufficient to ensure insulation in order to prevent a short circuit. Specific examples of such a material include SiO ₂ , Al ₂ O ₃ , MgO, AlN, ZrO ₂ , and TiO ₂ . In particular, when silicone is used as the covering member, it is preferable to use SiO ₂ as the protective film.

<Coating member>
The covering member is a light-transmitting member provided on at least the light-emitting element, and a wavelength conversion member that converts light from the light-emitting layer of the light-emitting element is a member contained in the light-transmitting resin. And in this Embodiment, as shown to FIG. 1A, the coating | coated member 2 is extended and provided from the upper surface to the side surface of the light emitting element 1, The edge part is lower than the side surface of the light emitting layer 11b. It is located on the side surface and located above the lower surface of the light emitting element. With such a configuration, it is possible to reduce the light emitted from the light emitting layer 11b to the outside without passing through the covering member 2, and to reduce the difference in the optical path length from the light emitting layer 11b to the wavelength conversion member. Unevenness can be reduced. That is, it is possible to efficiently mix colors and to easily make the color tone obtained by the color mixture uniform. In particular, unevenness can be further reduced because the wavelength conversion member is uniformly dispersed in the covering member.

  Note that the side surface of the light-emitting element refers to the side surface of the light-emitting element including the bonded substrate, and refers to the side surface of the semiconductor layer, the side surface of the protective film, and the side surface of the bonded substrate. And depending on the height (amount) of the covering member, etc., it may be provided so that the position height of the edge is different in a side view. For example, in the side view of the light emitting element, the edge of the covering member may be positioned below the center of the light emitting element rather than the end (corner in the top view). Thereby, it becomes a shape where an edge part is continuously provided from the side surface of a semiconductor layer to the side surface of a bonded substrate board. Even in such a case, the difference in color unevenness when the light emitting device is obtained can be reduced.

In order to provide a side surface of a light emitting element having a stacked structure of semiconductor layers so that the edge of the covering member is positioned, first, the semiconductor layer grown on the wafer is divided and the side surface is exposed. There is a need. A mold or the like is placed on the upper surface of the light-emitting element that is separated into small pieces of about 2 mm × 2 mm at most or about 450 μm × 450 μm to about 1 mm × 1 mm, which are commonly used. It is practically difficult to set. Therefore, in the present embodiment, the covering member is provided by dropping (potting) the covering member before curing, that is, the resin composition having fluidity from above the individual light emitting element. . At that time, the flowable resin composition does not flow out onto the member other than the light emitting element from the upper surface of the light emitting element without any enclosure, that is, the edge is located on the side surface of the light emitting element. In order to do so, the thixo ratio of the resin composition is prepared. In the present embodiment, the thixo ratio of the covering member is preferably in the range of 1.5 to 7, and more preferably in the range of 2 to 4. Here, the “thixo ratio” indicates a numerical value of the “resin composition” that is the coating member before curing, but may be expressed as “thixo ratio of the coating member” in the present specification. Further, the viscosity of the covering member was determined by using a cone / plate rotational viscometer (TVE-33HT manufactured by Toki Sangyo Co., Ltd.), cone 3 ° × R9.7, measurement temperature 25 ° C., and rotation speeds of 1 rpm and 10 rpm. Viscosity V _{1 rpm} and V _{10 rpm} are measured, and the value of the ratio V _{1 rpm} / V _{10 rpm} thixo ratio is obtained.

  By setting the thixo ratio of the covering member in the above range, a covering member having an edge on the side surface of the light-emitting element can be provided. Further, by adjusting the thixo ratio, the height of the covering member and the covering member The position of the edge can be controlled. At this time, since the position of the edge can be controlled also by the above-described protective film formation region or the like, even if the covering member has the same thixo ratio, depending on the combination with the protective film, The position can be varied, and the height and shape of the covering member can be varied.

  When dropping the resin composition, it is preferable to drop the resin composition from directly above the center in the top view of the light emitting element. As a result, a convex covering member having the highest position approximately right above the center of the light emitting element is provided, and the edge of the covering member is easily provided on the side surface of the lower layer of the light emitting layer on the entire circumference of the side surface of the light emitting element. Light emission with less unevenness can be obtained. Also, as the thixo ratio is higher, the shape at the time of application is maintained as it is, so that various forms of covering members can be obtained by appropriately optimizing the thixo ratio, the shape of the application nozzle, the application position, and the application amount. . This makes it possible to obtain various light distribution luminosities and light distribution chromaticities according to the use of the light emitting device.

  In order to make the covering member have the above-mentioned thixo ratio, it can be prepared by adding a wavelength conversion member or light-transmitting fine particles to the light-transmitting resin.

(Fine particles)
The fine particles preferably have a particle size in the range of about 0.01 μm to 10 μm, and more preferably in the range of about 0.1 μm to 1 μm. The particle shape may be any of a spherical shape, a needle shape, a phosphorus pen shape, an indeterminate shape, and the like, but a spherical shape is most suitable from the viewpoint of dispersibility in a translucent resin and light transmittance. Specific examples of the material include SiO ₂ , Al ₂ O ₃ , TiO ₂ , and a silicone resin, and these can be used alone or in combination.

(Wavelength conversion member)
Further, the wavelength conversion member is not particularly limited as long as it absorbs light from the light emitting element and converts the wavelength into light having a different wavelength. Specifically, nitride-based phosphors / oxynitride-based phosphors / sialon-based phosphors mainly activated by lanthanoid elements such as Eu and Ce, lanthanoid-based substances such as Eu, and transition metal-based substances such as Mn Alkaline earth halogen apatite phosphor, alkaline earth metal borate phosphor, alkaline earth metal aluminate phosphor, alkaline earth silicate, alkaline earth sulfide, alkali It is mainly activated by lanthanoid elements such as earth thiogallate, alkaline earth silicon nitride, germanate, or rare earth aluminate, rare earth silicate or Eu mainly activated by lanthanoid elements such as Ce. It is preferable that it is at least any one selected from organic and organic complexes. Specifically, (Y, Gd) ₃ (Al, Ga) ₅ O ₁₂ : Ce, (Ca, Sr, Ba) ₂ SiO ₄ : Eu, (Ca, Sr) ₂ Si ₅ N ₈ : Eu, CaAlSiN ₃ : Eu and the like.

(resin)
In addition, the translucent resin has a translucency capable of transmitting light from a light emitting element such as a silicone resin composition, a modified silicone resin composition, an epoxy resin composition, a modified epoxy resin composition, and an acrylic resin composition. And an insulating resin composition having the same. Furthermore, a silicone resin, an epoxy resin, a urea resin, a fluororesin, and a hybrid resin containing at least one of these resins can also be used.

  A light-emitting device 100 shown in FIG. 2 in which a light-emitting element with a covering member as described above is mounted on a base is a conductive material for applying a voltage from an external power source to the light-emitting element 1. It has the member 22 and the insulating member 21 for supporting them and insulating the conductive member so as to function as at least a pair of electrodes. Further, in addition to these members, a conductive wire 30 necessary for conduction, a protective element such as a Zener diode, and a sealing member 40 for sealing these electronic components can also be provided. Hereinafter, each member of the light emitting device will be described in detail.

(Substrate)
The substrate only needs to have an upper surface having an area where the light emitting element can be mounted, and in particular, a substrate having a substantially flat mounting region is preferable. Moreover, it is good also as a base | substrate provided with the recessed part which has a flat bottom face other than a flat substrate. The size and shape of the substrate can be arbitrarily selected according to the purpose and application. For example, the top view may be a quadrangle, rectangle, polygon, circle, ellipse, or a combination of these. it can. Similarly, when forming a recess, the shape of the bottom surface of the recess and the shape of the opening can be selected arbitrarily, and the side surface of the recess can be a surface perpendicular to the bottom surface, an inclined surface, or a step. Various selections, such as providing, can be made.

  The conductive member constituting the substrate functions as a pair of positive and negative electrodes, and is provided in a region where the light emitting element can be electrically connected to the conductive wire, bump, etc., and is electrically continuous with the external power source. It is also provided in a possible region (for example, an upper surface depending on the shape, such as an outer surface or a back surface of the base). In the case of a substrate having a recess, a pair of conductive members are provided in the recess (particularly the bottom surface).

  As a material of the conductive member, a material having excellent conductivity and thermal conductivity, and a material that is physically and chemically stable are preferable, such as copper, aluminum, gold, silver, tungsten, molybdenum, iron, nickel, cobalt, and the like. A metal or an alloy thereof can be used, and further, a surface plated can be used. In particular, the conductive member provided in the region irradiated with light from the light emitting element is preferably plated with a material that easily reflects the light. In particular, those having a reflectance in the visible range of 70% or more are preferable. Examples of such materials include gold, silver, copper, Pt, Pd, Al, W, Mo, Ru, Rh, and the like, and these can be used alone or in plural (alloys, laminates), particularly Ag and The alloy is preferred.

  The insulating portion 21 material constituting the base body 20 together with the conductive member 22 is provided so as to be interposed between at least a pair of conductive members. Since it is also a member for protecting the light emitting element, a member having a certain mechanical strength is preferable, and ceramic, resin, glass, glass epoxy resin, or the like can be used. Examples of ceramics include alumina and aluminum nitride. Further, as the resin, either a thermosetting resin or a thermoplastic resin can be used. Specifically, (a) an epoxy resin composition, (b) a silicone resin composition, (c) a modified epoxy resin composition such as a silicone-modified epoxy resin, and (d) a modified silicone resin composition such as an epoxy-modified silicone resin. (E) a polyimide resin composition, (f) a modified polyimide resin composition, and the like.

Then, fillers for imparting light shielding properties to these insulating members (particularly resins) and various additives as required can be mixed. Light transmittance is improved by mixing fine particles such as TiO ₂ , SiO ₂ , Al ₂ O ₃ , MgO, MgCO ₃ , CaCO ₃ , Mg (OH) ₂ , and Ca (OH) ₂ as fillers. Can be adjusted. It is preferable to shield about 60% or more of light from the light emitting element, more preferably about 90%. Various fillers as described above can be used alone or in combination of two or more.

(Sealing member)
The sealing member is a member that protects electronic components such as a light emitting element, a light receiving element, a protective element, and a conductive wire from dust, moisture, external force, and the like. As a material for the sealing member, a material having a light-transmitting property capable of transmitting light from the light-emitting element and having light resistance that is not easily deteriorated by them is preferable. In addition, a material having a refractive index and hardness close to those of the covering member provided on the light emitting element is preferable, and materials having the same physical properties are particularly preferable. Regarding the hardness, those having the same hardness after curing are preferable, and those having the same expansion coefficient are preferable. In particular, it is preferable that the sealing member provided so as to cover the cured covering member does not greatly deform the shape of the covering member due to stress generated during the curing. When the wavelength conversion member is included in the covering member, a problem such as a change in color tone due to deformation may occur.

  Further, as shown in FIG. 2, the sealing member 40 may be provided so as to cover the entire covering member 2, or a part thereof is exposed, that is, the sealing member is more than the upper surface of the covering member. You may provide so that the upper surface of may become a low position. When the conductive wire is bonded to the conductive member of the base, it is preferable to provide the conductive wire so as to be covered with the sealing member. In particular, it is preferable to provide all the conductive wires together with the covering member. In other words, it is preferable that the interface between the covering member and the sealing member is not formed outside (upper surface) of the light emitting device. Thereby, it becomes easy to protect a to-be-abdominated member from the outside, and also it can control that moisture etc. enter between a covering member and a sealing member.

  Specific materials for the sealing member include a silicone resin composition, a modified silicone resin composition, an epoxy resin composition, a modified epoxy resin composition, an acrylic resin composition, and the like that can transmit light from the light emitting element. An insulating resin composition having light properties can be given. In addition, a silicone resin, an epoxy resin, a urea resin, a fluororesin, and a hybrid resin containing at least one of these resins can be used. Furthermore, it is not limited to these organic materials, and inorganic materials such as glass and silica sol can also be used. In addition to such materials, a colorant, a light diffusing agent, a light reflecting material, various fillers, a wavelength conversion member (fluorescent member), and the like can be contained as desired. The filling amount of the sealing member may be an amount that covers the electronic component.

  The shape of the outer surface of the sealing member can be variously selected according to the light distribution characteristics and the like. For example, the directivity can be adjusted by making the upper surface into a convex lens shape, a concave lens shape, a Fresnel lens shape, or the like. In particular, a convex lens shape is preferable, and the vertex of the sealing member is preferably positioned above the vertex of the covering member of the light emitting element. In addition to the sealing member, a lens member may be provided. Furthermore, when using a molded body with a phosphor (for example, a plate-shaped molded body with a phosphor, a dome-shaped molded body with a phosphor, etc.), a material excellent in adhesion to the molded body with a phosphor is used as a sealing member. It is preferable to select. In addition to the resin composition, an inorganic substance such as glass can be used as the phosphor-containing molded body.

  The joining member is a member for mounting and connecting a light emitting element, a light receiving element, a protection element, and the like on the conductive member. Either a conductive bonding member or an insulating bonding member can be selected depending on the material of the bottom surface of the light emitting element to be mounted. As the insulating bonding member, an epoxy resin composition, a silicone resin composition, a polyimide resin composition, a modified resin thereof, a hybrid resin, or the like can be used. When these resins are used, a metal layer having a high reflectance such as an Al or Ag film or a dielectric reflecting film can be provided on the back surface of the light emitting element in consideration of deterioration due to light or heat from the semiconductor light emitting element. In this case, methods such as vapor deposition, sputtering, and bonding of thin films can be used. As the conductive bonding member, a conductive paste such as silver, gold, or palladium, a solder such as Au—Sn eutectic, a brazing material such as a low melting point metal, or the like can be used.

  The light emitting device according to the present invention is used for various display devices, lighting fixtures, displays, backlight light sources for liquid crystal displays, and also for image reading devices, projector devices, etc. in digital video cameras, facsimiles, copiers, scanners, etc. can do.

DESCRIPTION OF SYMBOLS 100 ... Light-emitting device 10 ... Light-emitting element with a covering member 1 ... Light-emitting element 11 ... Semiconductor layer
11a ... Upper layer
11b ... Light emitting layer
11c ... lower layer 12 ... electrode
121 ... Upper electrode
122 ... Lower electrode 13 ... Reflective member 14 ... Substrate (bonded substrate)
14a ... Projection (step)
14b ... Back metallization 15 ... Protective film 2 ... Coating member 20 ... Substrate 21 ... Insulating member 22 ... Conductive member 30 ... Conductive wire 40 ... Sealing member

Claims (8)

A light emitting device comprising a semiconductor layer having a light emitting layer;
On the light emitting element, a light emitting element with a covering member having a covering member containing a wavelength conversion member that converts light from the light emitting layer,
The light emitting element has a reflective member on the lower surface of the semiconductor layer,
The light emitting element with a covering member is characterized in that the edge of the covering member is located below the side surface of the light emitting layer and above the lower surface of the light emitting element.   The light emitting element with a covering member according to claim 1, wherein the light emitting element has a protective film on a side surface of the semiconductor layer.   The light emitting element with a covering member according to claim 1, wherein the light emitting element has an outer peripheral substrate larger than an outer periphery of the semiconductor layer on a lower side of the reflecting member.   The light emitting element with a covering member according to claim 3, wherein an edge of the covering member is located on an upper surface of the substrate.   The light emitting element with a covering member according to any one of claims 1 to 4, wherein the reflecting member is made of metal.   The light-emitting device which has a light emitting element with a covering member of any one of Claims 1 thru | or 5. Growing a semiconductor layer including a light emitting layer on a growth substrate;
Providing a reflective member on the surface of the semiconductor layer facing the growth substrate;
Removing the growth substrate to form a light emitting device with the semiconductor layer exposed;
A covering member containing a wavelength conversion member for converting light from the light emitting layer on the exposed semiconductor layer, the edge of which is lower than the side surface of the light emitting layer, and the lower surface of the light emitting element A step of being provided on the upper side,
The manufacturing method of the light emitting element with a coating | coated member which has this.   The said covering member is a manufacturing method of the light emitting element with a covering member of Claim 7 formed by dripping a resin composition.

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