JP2017050328A - Semiconductor light emitting device - Google Patents

Abstract

Embodiments provide a semiconductor light emitting device with improved light extraction efficiency. A semiconductor light emitting device according to an embodiment includes a first semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type, and between the first semiconductor layer and the second semiconductor layer. A light-emitting body including the light-emitting layer, a phosphor layer provided on the light-emitting body and including the phosphor, and a light-emitting layer provided on the phosphor layer, and emitting light emitted from the light-emitting layer and the phosphor. The transparent layer which permeate | transmits, and the some protrusion provided on the said transparent layer. [Selection] Figure 1

Description

  Embodiments relate to a semiconductor light emitting device.

  A semiconductor light emitting device includes a light emitting layer provided in a semiconductor. In order to increase the brightness of the semiconductor light emitting device, it is important to extract the emitted light of the light emitting layer from the semiconductor to the outside. For example, light incident at an angle larger than the critical angle from the semiconductor side is totally reflected at the boundary between the semiconductor and the outside. For this reason, all the light radiated | emitted from a light emitting layer cannot be taken out outside. By roughening the surface of the semiconductor and covering the surface with a low refractive index material such as a resin layer, it is possible to increase the proportion of light extracted to the outside. However, this is not enough. Therefore, there is a need for a technique for more efficiently extracting light emitted from the light emitting layer.

JP 2012-195402 A

  Embodiments provide a semiconductor light emitting device with improved light extraction efficiency.

  The semiconductor light emitting device according to the embodiment includes a first conductivity type first semiconductor layer, a second conductivity type second semiconductor layer, and light emission provided between the first semiconductor layer and the second semiconductor layer. A light emitting body including a layer, a phosphor layer provided on the light emitting body and including a phosphor, and a transparent layer provided on the phosphor layer and transmitting light emitted from the light emitting layer and the phosphor. And a plurality of protrusions provided on the transparent layer.

1 is a schematic cross-sectional view showing a semiconductor light emitting device according to a first embodiment. It is a schematic cross section which shows the manufacturing process of the semiconductor light-emitting device concerning 1st Embodiment. FIG. 3 is a schematic cross-sectional view showing a manufacturing process following FIG. 2. FIG. 4 is a schematic cross-sectional view showing a manufacturing process following FIG. 3. FIG. 5 is a schematic cross-sectional view showing a manufacturing process following FIG. 4. FIG. 6 is a schematic cross-sectional view showing a manufacturing process following FIG. 5. It is a schematic cross section which shows the semiconductor light-emitting device concerning 2nd Embodiment.

  Hereinafter, embodiments will be described with reference to the drawings. The same parts in the drawings are denoted by the same reference numerals, detailed description thereof will be omitted as appropriate, and different parts will be described. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between the parts, and the like are not necessarily the same as actual ones. Further, even when the same part is represented, the dimensions and ratios may be represented differently depending on the drawings.

  Furthermore, the arrangement and configuration of each part will be described using the X-axis, Y-axis, and Z-axis shown in each drawing. The X axis, the Y axis, and the Z axis are orthogonal to each other and represent the X direction, the Y direction, and the Z direction, respectively. Further, the Z direction may be described as the upper side and the opposite direction as the lower side.

  Description of embodiment is an illustration and the invention which concerns on a claim of this application is not necessarily limited to these. Further, the constituent elements described in each embodiment can be applied in common if technically possible. In the following description, the first conductivity type is described as n-type and the second conductivity type is defined as p-type. However, the present invention is not limited to this. The first conductivity type may be p-type and the second conductivity type may be n-type.

[First Embodiment]
FIG. 1 is a schematic cross-sectional view showing a semiconductor light emitting device 1 according to the first embodiment. As shown in FIG. 1, the semiconductor light emitting device 1 includes a light emitter 10, a phosphor layer 20, and a transparent layer 30.

  The light emitter 10 includes an n-type semiconductor layer 13, a light-emitting layer 15, and a p-type semiconductor layer 17. The light emitting layer 15 is provided between the n-type semiconductor layer 13 and the p-type semiconductor layer 17. The n-type semiconductor layer 13 includes, for example, n-type gallium nitride (GaN). The light emitting layer 15 has a quantum well structure including, for example, indium gallium nitride (InGaN) and GaN. The p-type semiconductor layer 17 includes, for example, p-type aluminum gallium nitride (AlGaN) and p-type GaN. The p-type AlGaN is provided between the light emitting layer 15 and the p-type GaN.

  The light emitter 10 has a first surface 10 a that is the surface of the n-type semiconductor layer 13 and a second surface 10 b that is the surface of the p-type semiconductor layer 17. The first surface 10a is roughened to improve the light extraction efficiency. The phosphor layer 20 is provided on the first surface 10a via the insulating layer 25. The insulating layer 25 improves the adhesion of the phosphor layer 20 to the light emitter 10. The insulating layer 25 is, for example, a silicon oxide layer.

  The phosphor layer 20 includes a phosphor 21 and a base material 23. The phosphor 21 includes, for example, a YAG-based or nitride-based phosphor, and converts part of blue light emitted from the light emitting layer 15 into yellow light or green light. The base material 23 is, for example, a silicone resin or an epoxy resin, and is transparent to the emitted light of the light emitting layer 15 and the emitted light of the phosphor 21. The phosphor 21 is dispersed in the base material 23. Here, “transparent” is not limited to the case of transmitting all of the emitted light, but includes the case of absorbing a part of the light.

  The transparent layer 30 is provided on the phosphor layer 20. The transparent layer 30 is transparent to the emitted light of the light emitting layer 15 and the emitted light of the phosphor 21. The transparent layer 30 is, for example, a silicone resin or a methyl resin. The transparent layer 30 is preferably made of the same material as the base material 23 of the phosphor layer 20 or a material having a lower refractive index than the base material 23.

  The semiconductor light emitting device 1 further includes a plurality of protrusions 40 provided on the transparent layer 30. The protrusion 40 has, for example, a width of 100 to 500 nanometers (nm) in the X direction and a height of 100 to 500 nm in the Z direction. The protrusion 40 is made of the same material as the transparent layer 30 or a material having a refractive index smaller than that of the transparent layer 30. The protrusion 40 is, for example, a silicone resin or a methyl resin. The plurality of protrusions 40 suppress total reflection of light propagating through the transparent layer 30 toward the outside. Thereby, the extraction efficiency of the light radiated | emitted from the light emitting layer 15 and the fluorescent substance 21 can be improved.

  Next, the structure of the semiconductor light emitting device 1 will be described in more detail with reference to FIG. The semiconductor light emitting device 1 includes an insulating layer 27, a p-side electrode 50, a p-side wiring 53, an n-side electrode 60, an n-side wiring 63 and a light shielding layer 70.

  The p-side electrode 50 is provided on the p-type semiconductor layer 17 on the second surface 10 b side of the light emitter 10. The p-side electrode 50 is in contact with and electrically connected to the p-type semiconductor layer 17. A material having a low contact resistance with respect to the p-type semiconductor layer 17 is used for the p-side electrode 50. The p-side electrode 50 is made of a material having a high reflectance with respect to the radiated light from the light emitting layer 15. For the p-side electrode 50, for example, silver (Ag) is used.

  The n-side electrode 60 is provided on the n-type semiconductor layer 13 on the second surface 10 b side of the light emitter 10. The n-side electrode 60 is in contact with the n-type semiconductor layer 13. A material having a low contact resistance with respect to the n-type semiconductor layer 13 is used for the n-side electrode 60. The n-side electrode 60 is made of a material having a high reflectance with respect to the emitted light from the light emitting layer 15. For the n-side electrode 60, for example, aluminum (Al) is used.

  The light emitter 10 is covered with the insulating layer 27 on the second surface 10b side. The insulating layer 27 is, for example, a silicon oxide layer. The insulating layer 27 covers the surface and side surfaces of the light emitter 10 on the second surface side, the p-side electrode 50 and the n-side electrode 60.

  The p-side wiring 53 covers the second surface 10 b of the light emitter 10 through the insulating layer 27 and the p-side electrode 50. The n-side wiring 63 covers the second surface side of the light emitter 10 through the insulating layer 27 and the n-side electrode 60. The p-side wiring 53 has a contact part 53a extending into an opening provided in the insulating layer 27, and is electrically connected to the p-side electrode 50 through the contact part 53a. The n-side wiring 63 has a contact part 63a in another opening provided in the insulating layer 27, and is electrically connected to the n-side electrode 60 through the contact part 63a.

  The light shielding layer 70 is provided so as to cover the side surface of the light emitter 10 through the insulating layer 27. The light shielding layer 70 blocks light emitted from the side surface of the light emitter 10. The light shielding layer 70 preferably includes a material that reflects the emitted light of the light emitting layer 15. The light shielding layer 70 includes, for example, aluminum.

  The semiconductor light emitting device 1 further includes a p-side pillar 55, an n-side pillar 65, and an insulating layer 80. The insulating layer 80 covers the second surface 10 b side of the light emitter 10 and the light shielding layer 70. For the insulating layer 80, for example, a black resin containing carbon or a white resin containing titanium oxide or the like is used. That is, the insulating layer 80 blocks light emitted from the light emitting layer 15.

  For example, the p-side pillar 55 passes through the insulating layer 80 and is connected to the p-side wiring 53. For example, the n-side pillar 65 penetrates the insulating layer 80 and is connected to the n-side wiring 63. For the p-side pillar 55 and the n-side pillar 65, for example, copper (Cu) is used.

  As shown in FIG. 1, the transparent layer 30 is provided so as to cover the upper surface 20a of the phosphor layer 20, the side surface 20s of the phosphor layer 20, and the side surface 80s of the insulating layer 80.

  Next, with reference to FIGS. 2A to 6C, a method for manufacturing the semiconductor light emitting device 1 according to the first embodiment will be described. FIG. 2A to FIG. 6C are schematic cross-sectional views sequentially showing the manufacturing process of the semiconductor light emitting device 1.

  As shown in FIG. 2A, the light emitter 10, the p-side electrode 50, and the n-side electrode 60 are formed on the substrate 100. The light emitter 10 is formed by selectively etching the n-type semiconductor layer 13, the light-emitting layer 15, and the p-type semiconductor layer 17 sequentially stacked on the substrate 100 using, for example, RIE (Reactive Ion Etching). Is done.

  The substrate 100 is, for example, a silicon substrate. The n-type semiconductor layer 13, the light emitting layer 15, and the p-type semiconductor layer 17 are epitaxially grown on the substrate 100 using, for example, MOCVD (Metal Organic Chemical Vapor Deposition). The n-type semiconductor layer 13 includes, for example, a buffer layer formed on the substrate 100 and an n-type GaN layer formed thereon. The buffer layer includes, for example, aluminum nitride (AlN), AlGaN, or the like.

  The light emitter 10 includes a light emitting portion 10e including an n-type semiconductor layer 13, a light emitting layer 15, and a p-type semiconductor layer 17, and a non-light emitting portion 10f from which the light emitting layer 15 and the p-type semiconductor layer 17 are removed. The p-side electrode 50 is provided on the p-type semiconductor layer 17 on the light emitting unit 10e. The n-side electrode 60 is provided on the n-type semiconductor layer 13 on the non-light emitting portion 10f.

  As shown in FIG. 2B, the insulating layer 27, the p-side wiring 53, the n-side wiring 63, and the light shielding layer 70 that cover the light emitter 10 are formed. The insulating layer 27 is a silicon oxide layer, for example, and is formed using CVD (Chemical Vapor Deposition). The insulating layer 27 covers the surfaces of the light emitter 10 and the substrate 100.

  The p-side wiring 53 is provided on the insulating layer 27 in the light emitting unit 10e. The p-side wiring 53 is electrically connected to the p-side electrode 50 through a contact hole 27 a provided in the insulating layer 27.

  The n-side wiring 63 is provided on the insulating layer 27 across the non-light emitting portion 10f and the light emitting portion 10e. In the non-light emitting unit 10 f, the n-side wiring 63 is electrically connected to the n-side electrode 60 through a contact hole 27 b provided in the insulating layer 27.

  The light shielding layer 70 is formed so as to cover the side surface of the light emitter 10 with the insulating layer 27 interposed therebetween. The p-side wiring 53, the n-side wiring 63, and the light shielding layer 70 include, for example, an aluminum layer that is simultaneously formed and is in contact with the insulating layer 27, and a copper layer formed thereon.

  As shown in FIG. 2C, the p-side pillar 55 and the n-side pillar 65 are formed. For example, a resist layer 101 that covers the light emitter 10 and the substrate 100 is formed. The resist layer 101 has openings 55a and 65a formed using, for example, photolithography. The openings 55a and 65a communicate with the p-side wiring 53 and the n-side wiring 63, respectively. Subsequently, the p-side pillar 55 and the n-side pillar 65 are formed in the openings 55a and 65a of the resist layer 101 by using, for example, a copper plating method.

  As shown in FIG. 3A, an insulating layer 80 is formed. After removing the resist layer 101, for example, a silicone resin or an epoxy resin containing a light shielding material is applied onto the substrate 100 and cured. Thereby, the insulating layer 80 covering the p-side pillar 55, the n-side pillar 65, and the light emitter 10 is formed. In each figure after FIG. 3A, the display is shown upside down in FIG.

  As shown in FIG. 3B, the substrate 100 is removed from the light emitter 10. For example, the substrate 100 is thinned by grinding and then removed by wet etching. For example, when a sapphire substrate is used as the substrate 100, the substrate 100 can be removed using laser lift-off.

  As shown in FIG. 3C, the first surface 10a of the light emitter 10 is roughened. For example, the first surface 10a exposed after removing the substrate 100 is roughened by wet etching with an alkaline etchant.

  As shown in FIG. 4A, an insulating layer 25 is formed on the first surface 10a. The insulating layer 25 is a silicon oxide layer formed using, for example, a plasma CVD method. The insulating layer 25 is also formed on the insulating layer 27 exposed between the adjacent light emitters 10. If the insulating layer 25 and the insulating layer 27 are the same silicon oxide layer, they are integrated.

  As shown in FIG. 4B, the phosphor layer 20 is formed on the light emitter 10. The phosphor layer 20 can be formed, for example, by attaching a resin sheet containing a phosphor on the light emitter 10.

  As shown in FIG. 4C, a part of the insulating layer 80 is removed by, for example, grinding or polishing on the lower surface 80a of the insulating layer 80 opposite to the phosphor layer 20. Thereby, the end surface 55s of the p-side pillar 55 and the end surface 65s of the n-side pillar 65 are exposed.

  As shown in FIG. 5A, for example, a dicing sheet 103 is attached to the lower surface 80 a of the insulating layer 80. Subsequently, as shown in FIG. 5B, the phosphor layer 20 and the insulating layer 80 are divided, and a groove 105 is formed between the adjacent light emitters 10. The groove 105 is formed using, for example, a dicing blade.

  As shown in FIG. 5C, a resin layer 130 that covers the upper surface of the phosphor layer 20 and fills the inside of the groove 105 is formed. The resin layer 130 can be formed using, for example, vacuum forming.

  As shown in FIG. 6A, the resin layer 110 is formed on the resin layer 130, and the molded sheet 120 is further pressure-bonded. After the resin layer 110 is applied on the resin layer 130, for example, a heat treatment is applied to obtain a semi-cured state, that is, a so-called B stage. Subsequently, the surface of the molded sheet 120 having a plurality of fine recesses 120p is brought into contact with the resin layer 110 and is applied with pressure. Further, the resin layer 110 is subjected to heat treatment and cured.

  As shown in FIG. 6B, a groove 115 is formed between the adjacent phosphor layers 20, and the resin layers 110 and 130 are divided. Thereby, the resin layer 130 is divided into the transparent layer 30 covering the phosphor layer 20. The groove 115 can be formed using, for example, a dicing blade. In this case, a dicing blade thinner than the dicing blade used for forming the groove 105 is used in the step shown in FIG.

  As shown in FIG. 6C, the molded sheet 120 is peeled from the surface of the transparent layer 30. A plurality of protrusions 40 are formed on the transparent layer 30 after the molded sheet 120 is peeled off. That is, the concave portion 120p of the molded sheet 120 is inverted and transferred, and as a result, the resin layer 110 is molded into the plurality of protrusions 40.

  Thus, in this embodiment, it becomes possible to form the some protrusion 40 on the transparent layer 30, and can take out the light from the transparent layer 30 to the exterior. Further, the molded sheet 120 protects the surface of the transparent layer 30 when the resin layer 130 is divided.

  The method for forming the protrusion 40 is not limited to the above example. For example, a photosensitive resist may be applied on the resin layer 130, and a protrusion made of the photosensitive resist having a predetermined shape may be formed using photolithography.

[Second Embodiment]
FIG. 7 is a schematic cross-sectional view showing the semiconductor light emitting device 2 according to the second embodiment. As shown in FIG. 7, the semiconductor light emitting device 2 includes leads 201 and 203 and a semiconductor light emitting element 200. The semiconductor light emitting element 200 is mounted on the lead 201 via a bonding metal 205.

  The semiconductor light emitting element 200 includes a substrate 210 and a light emitter 220. The light emitter 220 is provided on the substrate 210 with the bonding layer 230 interposed therebetween. The substrate 210 is, for example, a conductive silicon substrate. The bonding layer 230 includes, for example, a solder material and bonds the substrate 210 and the light emitter 220. The light emitter 220 includes, for example, an n-type semiconductor layer 221, a light-emitting layer 223, and a p-type semiconductor layer 225. The light emitting layer 223 is provided between the n-type semiconductor layer 221 and the p-type semiconductor layer 225.

  The semiconductor light emitting device 200 further includes a p-side electrode 240 and an n-side electrode 250. The p-side electrode 240 is provided between the p-type semiconductor layer 225 and the bonding layer 230. The p-side electrode 240 is electrically connected to the p-type semiconductor layer 225. The p-side electrode 250 is provided so as to reflect light emitted from the light emitting layer 223, for example.

  The bonding layer 230 is in contact with the cap layer 245 that covers the p-side electrode 240 and is electrically connected to the p-side electrode 240. The cap layer 245 is a metal layer containing, for example, aluminum. That is, the p-side electrode 240 is electrically connected to the lead 201 through the bonding layer 230, the substrate 210, and the bonding metal 205.

  The n-side electrode 250 is provided on the upper surface of the light emitter 220 and is electrically connected to the n-type semiconductor layer 221. The n-side electrode 250 is electrically connected to the lead 203 via the metal wire 255.

  Furthermore, the semiconductor light emitting device 2 includes a sealing layer 260, a phosphor layer 270, and a transparent layer 280. The sealing layer 260 covers the leads 201 and 203 and the semiconductor light emitting element 200 and shields them from the outside air. The sealing layer 260 is, for example, a silicone resin or an epoxy resin, and is formed using vacuum forming. The sealing layer 260 is transparent to the light emitted from the light emitting layer 223.

  The phosphor layer 270 is formed on the sealing layer 260. The phosphor layer 270 includes the phosphor 21 and the base material 23. For the base material 23, the same material as the sealing layer 260 or a material having a lower refractive index than the sealing layer 260 is used. The base material 23 is, for example, a silicone resin.

  The transparent layer 280 is formed on the phosphor layer 270. The transparent layer 280 is transparent to the light emitted from the light emitting layer 223 and the phosphor 21. The transparent layer 280 is made of the same material as the base material 23 of the phosphor layer 270 or a material having a lower refractive index than the base material 23. The transparent layer 280 is, for example, a silicone resin or a methyl resin.

  The semiconductor light emitting device 2 further includes a plurality of protrusions 290 provided on the transparent layer 280. The protrusion 290 has, for example, a width of 100 to 500 nm in the X direction and a height of 100 to 500 nm in the Z direction. The protrusion 290 is, for example, a silicone resin or a methyl resin. The protrusion 290 is made of the same material as the transparent layer 280 or a material having a refractive index lower than that of the transparent layer 280. The plurality of protrusions 290 suppress total reflection of light propagating through the transparent layer 280 toward the outside. Thereby, the extraction efficiency of the light radiated | emitted from the light emitting layer 223 and the fluorescent substance 21 can be improved.

In the present specification, “nitride semiconductor” means B _x In _y Al _z Ga _1-xyz N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1, 0 ≦ x + y + z ≦ 1) includes a group III-V compound semiconductor, and further includes a mixed crystal containing phosphorus (P), arsenic (As), etc. in addition to N (nitrogen) as a group V element. Furthermore, those having the above composition and further containing various elements added to control various physical properties such as conductivity type, and those further containing various elements included unintentionally, It is included in “nitride semiconductor”.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1, 2 ... Semiconductor light-emitting device, 10 ... Light-emitting body, 10a ... 1st surface, 10b ... 2nd surface, 10e ... Light-emitting part, 10f ... Non-light-emitting part, 13, 221 ... n-type semiconductor layer, 15, 223 ... light-emitting layer, 17, 225 ... p-type semiconductor layer, 20, 270 ... phosphor layer, 20a ... upper surface, 20s, 80s ··· Side surface, 21 ... phosphor, 23 ... base material, 25, 27, 80 ... insulating layer, 27a, 27b ... contact hole, 30,280 ... transparent layer, 40,290 ..Protrusions, 50, 240 ... p-side electrode, 53 ... p-side wiring, 53a, 63a ... contact part, 55 ... p-side pillar, 55a ... opening, 55s, 65s ... End face, 60, 250 ... n-side electrode, 63 ... n-side Line 65, n-side pillar, 70 ... shading layer, 80a ... lower surface, 100, 210 ... substrate, 101 ... resist layer, 103 ... dicing sheet, 105, 115 ... -Groove, 110, 130 ... resin layer, 120 ... molded sheet, 120p ... recess, 200 ... semiconductor light emitting element, 201, 203 ... lead, 205 ... bonding metal, 220- ..Luminescent body, 230 ... Junction layer, 245 ... Cap layer, 255 ... Metal wire, 260 ... Sealing layer

Claims (5)

A light emitting body including a first semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type, and a light emitting layer provided between the first semiconductor layer and the second semiconductor layer;
A phosphor layer provided on the light emitter and including a phosphor;
A transparent layer that is provided on the phosphor layer and transmits the light emitted from the light emitting layer and the phosphor;
A plurality of protrusions provided on the transparent layer;
A semiconductor light emitting device comprising: The phosphor layer includes a base material in which the phosphor is dispersed,
The semiconductor light emitting device according to claim 1, wherein a refractive index of the transparent layer with respect to the emitted light of the light emitting layer is smaller than a refractive index of the base material with respect to the emitted light.   The semiconductor light emitting device according to claim 1, wherein the transparent layer includes the same material as the base material.   4. The semiconductor light emitting device according to claim 1, wherein a refractive index of the plurality of protrusions with respect to the emitted light of the light emitting layer is smaller than a refractive index of the transparent layer with respect to the emitted light. The semiconductor light emitting device according to claim 1, wherein the plurality of protrusions include the same material as the transparent layer.

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