KR20100036760A - Light emitting diode and method for fabricating the same - Google Patents

Abstract

PURPOSE: A light emitting diode and a method for manufacturing the same are provided to improve light reflective efficiency using nano islands including Ag in order to scatter light which is generated from an active layer. CONSTITUTION: A first conductive semiconductor layer, an active layer and a second conductive semiconductor layer are formed on a conductive substrate(71). A metal nano island layer is formed on the second conductive semiconductor layer. The metal nano island layer includes a plurality of metal nano islands(61) including Ag which is formed on the second conductive layer. A metal reflective layer(63) covers the metal nano island layer.

Description

LIGHT EMITTING DIODE AND METHOD FOR FABRICATING THE SAME

The present invention relates to a light emitting diode, and more particularly, to a light emitting diode having an improved metal reflective layer structure and a method of manufacturing the same.

Light emitting diodes, such as flip type light emitting diodes and vertical electrode type light emitting diodes, include a first conductive semiconductor layer (e.g., N-GaN), an active layer, and a second conductive semiconductor layer (e.g., P-GaN) formed on a substrate. And a metal reflective layer formed on the second conductivity-type semiconductor layer to reflect light generated from the active layer toward the substrate.

Silver (Ag) and aluminum (Al) have high light reflectivity in the visible light region. However, since these materials have limitations in the adhesion properties and ohmic properties of the surface when deposited on surfaces such as nitride semiconductors and oxide sapphire, a thin metal or conductive oxide film is deposited before the reflective material. However, since most of the materials used to improve the adhesion properties and ohmic properties before the reflective material do not have excellent reflectivity and transparency, there is a problem in that the reflectivity of Ag and Al is substantially reduced.

The problem to be solved by the present invention is improved light extraction effect by having a metal nano-island layer consisting of a plurality of nano-isles including Ag in the light emitting diode having a structure of the metal reflective layer, and a metal reflective layer formed to cover the metal nano-isolated layer It is to provide a light emitting diode having a and a method of manufacturing the same.

According to one aspect of the invention, the first conductive semiconductor layer, the active layer and the second conductive semiconductor layer; A metal nano island layer including a plurality of metal nano islands including Ag formed on the second conductive semiconductor layer; A light emitting diode including a metal reflective layer formed by covering the metal nano-island layer is provided.

Preferably, the metal nano island layer may be made of Ag or Ag alloy.

Preferably, the metal nanoislets may have a size of less than 50 nm (not including 0).

Preferably, the metal reflective layer may include Ag or Al.

Preferably, the light emitting diode may further include an adhesive metal layer formed by covering the metal nano island layer between the metal nano island layer and the metal reflective layer.

According to another aspect of the invention, forming a first conductive semiconductor layer, an active layer and a second conductive semiconductor layer on a substrate; Depositing a metal layer including Ag on the second conductivity type semiconductor layer; Heat-treating the deposited metal layer to form a metal nanoisland layer consisting of a plurality of metal nanoisles; Provided is a light emitting diode manufacturing method comprising forming a metal reflective layer covering the metal nanoislet layer.

Preferably, the heat treatment may be performed for 10 minutes or more at a temperature of 850 ℃ ~ 1100 ℃.

Preferably, the metal nano island layer may be made of Ag or Ag alloy.

Preferably, the metal reflective layer may include Ag or Al.

Preferably, the light emitting diode manufacturing method may further include forming an adhesive metal layer covering the metal nanoisland layer between the metal reflection layer and the metal nanoislet layer before forming the metal reflection layer.

According to the present invention, after forming a metal nano island layer composed of a plurality of metal nano islands containing Ag on a second conductivity type semiconductor layer, for example, a P-GaN layer, a metal reflective layer including Ag or Al is formed thereon. By forming, the adhesion of the metal reflective layer to the P-GaN layer is enhanced, and nanoislets containing Ag scatter light generated from the active layer to improve light reflection efficiency.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided as examples to ensure that the spirit of the present invention can be fully conveyed to those skilled in the art. Accordingly, the present invention is not limited to the embodiments described below and may be embodied in other forms. And, in the drawings, the width, length, thickness, etc. of the components may be exaggerated for convenience. Like numbers refer to like elements throughout.

1 is a cross-sectional view illustrating a light emitting diode according to an embodiment of the present invention.

Referring to FIG. 1, compound semiconductor layers including an N-type semiconductor layer 55, an active layer 57, and a P semiconductor layer 59 are positioned on the conductive substrate 71. The conductive substrate 71 is a substrate such as Si, GaAs, GaP, AlGaINP, Ge, SiSe, GaN, AlInGaN or InGaN, but Al, Zn, Ag, W, Ti, Ni, Au, Mo, Pt, Pd, Cu, It may be a single metal of Cr or Fe or an alloy substrate thereof. Meanwhile, the compound semiconductor layers are III-N series compound semiconductor layers. For example, it is a (Al, Ga, In) N semiconductor layer.

A metal nano island layer including a plurality of metal nano islands 61 including Ag is formed between the compound semiconductor layers and the conductive substrate 71, and covers the metal nano island layer to include Ag or Al. Reflective layer 63 is formed.

The plurality of metal nanoisles 61 constituting the metal nanoisle layer may be metal nanoisles made of pure Ag or Ag alloy. As the Ag alloy, for example, Ag is the main component and Cu, Al, Sn, Au, Mg, Zn, Sc, Hf, Zr, Te, Se, Ta, W, Nb, Si, Ni, Co, Mo, Cr , At least one selected from the group consisting of Mn, Hg, Pr, and La, for example, may be included in a content of 0.5-10 atomic%.

The metal nano islands 61 of the metal nano island layer may function as an intermediate layer for attaching the metal reflective layer 63 to the P-type semiconductor layer 59 and a scattering layer of light. The size of the metal nanoislets 61 containing Ag is suitably less than 50 nm (not including 0). Metal nanoisles 61 of this size are deposited on a P-type semiconductor layer 59 by depositing a metal containing Ag (pure Ag or Ag alloy described above) to a thickness of 10 nm or less (not including 0), for example. It may be formed through a heat treatment for about 10 minutes at a temperature of 850 ℃ ~ 1100 ℃.

Metal nanoislets 61 having a size of less than 50 nm (not including 0) are formed on the P-type semiconductor layer 59 when the metal reflecting layer 63 is deposited on the P-type semiconductor layer 59 in a subsequent process. It serves as an intermediate layer to enhance the adhesion of the metal reflective layer 63 to the.

In addition, the metal nanoisles 61 of the metal nanoisle layer cause scattering of light generated from the active layer 57. Thus, the metal nanoisland layer functions as a light scattering layer.

The metal reflective layer 63 is formed of a metal material having a high reflectance such as silver (Ag) or aluminum (Al). In addition, the metal reflective layer 63 may use an alloy of silver (Ag) or an alloy of aluminum (Al).

The protective metal layer 65 may prevent the metal elements from diffusing from the adhesive layer 67 or the conductive substrate 71 into the metal reflective layer 63 to maintain the reflectivity of the metal reflective layer 63. The metal used for the protective metal layer 65 may be selected by focusing on the adhesive force with the metal reflective layer 63 and the function of preventing the yellowing of the metal reflective layer 63 rather than the light reflection function. The protective metal layer 65 may be formed of, for example, Ni, Ti, Ta, Pt, W, Cr, Pd, or the like. However, the present invention is not limited thereto.

The adhesive layer 67 improves the adhesion between the conductive substrate 71 and the metal reflective layer 61 to prevent the conductive substrate 71 from being separated from the metal reflective layer 61.

Meanwhile, the electrode pad 83 is positioned on the upper surface of the compound semiconductor layers to face the conductive substrate 71. Accordingly, light can be emitted by supplying a current through the conductive substrate 71 and the electrode pad 83.

2 to 8 are drawings or photographs for explaining a method of manufacturing a light emitting diode according to an embodiment of the present invention.

Referring to FIG. 2, compound semiconductor layers are formed on the sacrificial substrate 51. The sacrificial substrate 51 may be a sapphire substrate, but is not limited thereto and may be another hetero substrate. The compound semiconductor layers include an N semiconductor layer 55, an active layer 57, and a P-type semiconductor layer 59. The compound semiconductor layers are III-N-based compound semiconductor layers, and may be grown by a process such as metal organic chemical vapor deposition (MOCVD) or molecular beam deposition (MBE).

Meanwhile, the buffer layer 53 may be formed before forming the compound semiconductor layers. The buffer layer 53 is adopted to mitigate lattice mismatch between the sacrificial substrate 51 and the compound semiconductor layers, and may generally be a gallium nitride-based material layer.

Referring to FIG. 3, a metal including Ag is deposited on the P-type semiconductor layer 59 to form a metal layer 60. The material of the metal layer 60 may be pure Ag or Ag alloy. Ag alloy is composed mainly of Ag, Cu, Al, Sn, Au, Mg, Zn, Sc, Hf, Zr, Te, Se, Ta, W, Nb, Si, Ni, Co, Mo, Cr, Mn, Hg, At least one selected from the group consisting of Pr and La may be included, for example, in a content of 0.5-10 atomic%. The metal layer 60 may be deposited using a known deposition method such as a thermal evaporator, an e-beam evaporator, a sputtering, a laser evaporator, or the like. The deposition thickness of the metal layer 60 used may be, for example, 10 nm or less.

Referring to FIG. 4, after forming the metal layer 60, for example, heat treatment is performed in an atmosphere such as vacuum, nitrogen, or argon. Accordingly, the metal layer 60 is formed on the P-type semiconductor layer 59 is formed of a metal nano island layer consisting of a plurality of nano islands 61 (see the photo of FIG. 5). The metal nanoisles 62 of the metal nanoisle layer are formed with a size of, for example, 50 nm or less (not including 0). The heat treatment temperature may be heat treated at a temperature of, for example, 850 ° C. to 1100 ° C. or more for 10 minutes or more above a temperature at which the metal nano islands 61 may be formed from the metal layer 60 by heat.

Referring to FIG. 6, in a state in which a metal nano island layer made of metal nano islands 61 is formed, a metal reflective layer 63 covering the metal nano island layer is formed. The metal reflective layer 63 may be, for example, 50 nm-100 nm. The metal reflective layer 63 may be formed using, for example, plating or vapor deposition of silver (Ag) or aluminum (Al). Silver (Ag) alloy or aluminum (Al) alloy may be used for the metal reflective layer 63.

Referring to FIG. 7, a protective metal layer 65 is formed on the metal reflective layer 63. The protective metal layer 65 may be formed of, for example, Ni, Ti, Ta, Pt, W, Cr, Pd, or the like. However, the present invention is not limited thereto.

The conductive substrate 71 is formed on the protective metal layer 65. The conductive substrate 71 is a substrate such as Si, GaAs, GaP, AlGaINP, Ge, SiSe, GaN, AlInGaN or InGaN, but Al, Zn, Ag, W, Ti, Ni, Au, Mo, Pt, Pd, Cu, It can be formed by attaching a single metal of Cr or Fe or an alloy substrate thereof onto the compound semiconductor layers. In this case, the conductive substrate 71 may be attached to the protective metal layer 65 through the adhesive layer 67, and the conductive substrate 71 may be formed using a plating technique. That is, the conductive substrate 71 may be formed by plating a metal such as Cu or Ni on the protective metal layer 65, and an adhesive layer 67 may be added to improve adhesion.

Referring to FIG. 8, the sacrificial substrate 51 is separated from the compound semiconductor layers. The sacrificial substrate 51 may be separated by laser lift off (LLO) technology or other mechanical or chemical methods. At this time, the buffer layer 53 is also removed to expose the N-type semiconductor layer 59.

Subsequently, an electrode pad 83 is formed on the N-type semiconductor layer 55. Thereafter, the plurality of vertical light emitting diodes shown in FIG. 1 may be manufactured by cutting the conductive substrate 71 and separating them into individual light emitting diode chips. At this time, the conductive substrate 71 is cut along the predefined scribing lines.

9 and 10 are views for explaining a method of manufacturing a light emitting diode according to another embodiment of the present invention.

In the exemplary embodiment of the present invention described with reference to FIGS. 1 to 8, a metal nano island layer including metal nano islands 61 is formed on the P-type semiconductor layer 59, and then the metal nano islands 61 are covered. The metal reflective layer 63 was formed. In another embodiment of the present invention is almost the same as the embodiment shown in Figures 1 to 8, the deformation was made in the process of forming the metal nano-isle 61 and the metal reflective layer 63 described in Figures 4 and 6 .

In another embodiment of the present invention, as shown in FIG. 4, the metal nanoisles consisting of metal nanoisles 61 are formed on the P-type semiconductor layer 59, and then the metal nanoisles as shown in FIG. 9. The adhesive metal layer 62 is thinly deposited to cover 59, for example, about 5 kV to 10 kV. For example, Pt, Ti, or Cr may be used as the adhesive metal layer 62, but is not limited thereto.

Thereafter, referring to FIG. 10, a metal reflective layer 63 covering the adhesive metal layer 62 is formed. The metal reflective layer 63 may be, for example, 50 nm-100 nm, as described in FIG. 6, and may be formed using a plating or deposition technique, for example, silver (Ag) or aluminum (Al), and a silver (Ag) alloy. Alternatively, aluminum (Al) alloys may be used.

Since the adhesive metal layer 62 is thin, synergistic effect with the metal nano islands 61 can be improved without increasing the light reflection, thereby improving the adhesion of the metal reflective layer 63, thereby improving reliability of the light emitting diode. have.

The present invention is not limited to the above described embodiments, and various modifications and changes can be made by those skilled in the art, which are included in the spirit and scope of the present invention as defined in the appended claims.

For example, in the exemplary embodiment of the present invention, a vertical light emitting diode among light emitting diodes having a reflective metal layer has been described, but the present invention is not limited thereto, and the first conductive semiconductor layer, the active layer, and the second conductive semiconductor are not limited thereto. Any light emitting diode having a structure of a metal reflective layer for reflecting light generated from the active layer on the structure of the layer may be variously modified without departing from the spirit of the present invention.

In addition, in the exemplary embodiment of the present invention, the light emitting diode having the conductive substrate on the metal reflective layer and having the electrodes above and below the light emitting diode was described. However, the insulating substrate is provided without the conductive substrate and the N-type electrode is formed on one surface. , A P-type electrode may be formed.

1 is a cross-sectional view illustrating a light emitting diode according to an embodiment of the present invention.

2 to 8 are drawings or photographs for explaining a method of manufacturing a light emitting diode according to an embodiment of the present invention.

9 and 10 are views for explaining a method of manufacturing a light emitting diode according to another embodiment of the present invention.

Claims (10)

A first conductive semiconductor layer, an active layer and a second conductive semiconductor layer; A metal nano island layer including a plurality of metal nano islands including Ag formed on the second conductive semiconductor layer; A light emitting diode comprising a metal reflective layer formed to cover the metal nano-island layer. The method according to claim 1, The metal nano island layer is a light emitting diode made of Ag or Ag alloy. The method according to claim 1, The metal nanoisles have a size of less than 50nm (not including 0). The method according to claim 1, The metal reflective layer includes Ag or Al. The method according to claim 1, The light emitting diode of claim 1, further comprising an adhesive metal layer formed between the metal nano island layer and the metal reflective layer to cover the metal nano island layer. Forming a first conductive semiconductor layer, an active layer and a second conductive semiconductor layer on the substrate; Depositing a metal layer including Ag on the second conductivity type semiconductor layer; Heat-treating the deposited metal layer to form a metal nanoisland layer consisting of a plurality of metal nanoisles; Forming a metal reflective layer covering the metal nano-island layer. The method according to claim 6, The heat treatment is a light emitting diode manufacturing method is performed for 10 minutes or more at a temperature of 850 ℃ ~ 1100 ℃. The method according to claim 6, The metal nano island layer is made of Ag or Ag alloy. The method according to claim 6, The metal reflective layer is a light emitting diode manufacturing method comprising Ag or Al. The method according to claim 6, And forming an adhesive metal layer covering the metal nano island layer between the metal reflective layer and the metal nano island layer before forming the metal reflective layer.

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