JP2009272656A - Semiconductor light-emitting element, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting element which is easily worked and has good emission performance. <P>SOLUTION: A conductive substrate 8 is made of iron-nickel alloy, and a conductive adhesive is made of Au-Sn solder 7. A manufacturing method of a semiconductor light-emitting element includes the steps of: growing a laminate of GaN based semiconductor layers including light emitting layer, on a GaAs (111) A substrate 1; fixing an electrode surface provided on a surface of the laminate and the conductive substrate with a conductive adhesive; and removing the GaAs (111) A substrate 1. The GaAs (111) A substrate 1 is removed by wet etching with an ammonia based etchant. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a blue and green light emitting element using a gallium nitride (GaN) based semiconductor and a method for manufacturing the same.

  FIG. 6 shows, for example, the Nikkei Science October issue (1994), p. FIG. 44 is a cross-sectional view showing the structure of a GaN-based blue and green light-emitting element described in 44 using a commercially available sapphire substrate.

  This blue and green light emitting element is formed on an epitaxial wafer composed of a sapphire substrate 11, a GaN buffer layer 12 formed on the substrate 11, and a hexagonal GaN epitaxial layer 13 formed on the GaN buffer layer 12. In addition, a cladding layer 14, a light emitting layer 15, a cladding layer 16, and a GaN epitaxial layer 17 are formed in this order, and a nitride semiconductor layer is laminated. Electrodes 18 and 19 are formed on the GaN epitaxial layers 13 and 17, respectively. Further, in the blue and green light emitting elements, the GaN buffer layer 12 is provided to alleviate strain due to a difference in lattice constant between the sapphire substrate 11 and the GaN epitaxial layer 13.

  Since the blue and green light emitting elements described above use insulating sapphire as the substrate 11, when forming an element by forming an electrode, it is necessary to form two types of electrodes on the same surface side. Therefore, it is necessary to perform patterning by photolithography twice or more, and further, it is necessary to perform nitride etching by reactive ion etching, which requires a complicated process.

  Further, since sapphire has a high hardness, there is also a problem that it is difficult to cut during element isolation. Therefore, an attempt has been made to use conductive GaAs as a substrate instead of sapphire having such defects.

  For example, in Journal of Crystal Growth 164 (1996), p149, the growth of cubic GaN on a GaAs (100) surface was reported in Journal of Electronic Materials vol. 24 No. 4 (1995), p213 reports the growth of GaN on the GaAs (111) A and GaAs (111) B surfaces by the MOVPE method (metal organic vapor phase epitaxy).

  JP-A-8-181070 discloses an organometallic chloride vapor phase epitaxial method capable of obtaining a GaN epitaxial layer having good characteristics in a temperature range of 700 ° C. (700 ° C.) or higher. In this method, a group III organic metal, which is a raw material for a III compound semiconductor, is introduced into a reaction tube simultaneously with hydrogen chloride, thereby supplying a group III element as a chloride onto a substrate.

JP-A-8-181070

Nikkei Science October issue (1994), p. 44 Journalof Crystal Growth 164 (1996), p149 Journalof Electronic Materials vol. 24 No. 4 (1995), p213

  The conventional GaN-based semiconductor layer light-emitting elements use insulating and hard sapphire for the substrate, which requires a complicated process for electrode preparation and difficult processing such as cutting during element separation. It is as follows. Therefore, such a problem can be solved by using a substrate such as conductive GaAs.

  However, when a GaAs substrate is used, for example, light emitted from the light emitting layer of the GaN-based semiconductor layer is absorbed by the GaAs substrate, and the intensity of reflected light from the substrate is lowered. Therefore, when a GaAs substrate is used, sufficient light emission intensity cannot be obtained. This is thought to be because the band gap of the GaAs substrate (difference in quantum state energy of electrons in the crystal) is smaller than that of the GaN-based semiconductor layer.

  An object of the present invention is to provide a semiconductor light emitting device that can be easily manufactured and solves the above-described problems and emits light, and a method for manufacturing the same.

A method of manufacturing a semiconductor light emitting device according to the present invention includes a conductive substrate and an electrode surface provided on a surface of a laminate composed of a gallium nitride (GaN) semiconductor layer including a light emitting layer grown on a growth substrate. After bonding using an adhesive, the growth substrate is removed for manufacturing. Further, this manufacturing method is characterized in that a band gap of the growth substrate is smaller than a band gap of the light emitting layer. In this manufacturing method, the growth substrate is a cubic (111) substrate, and the gallium nitride (GaN) semiconductor layer is a hexagonal crystal. In this manufacturing method, the growth substrate is removed by wet etching using an ammonia-based etchant. In this manufacturing method, the growth substrate is a cubic (111) substrate made of gallium arsenide (GaAs), indium phosphide (InP), indium arsenide (InAs), or gallium phosphide (GaP), and the gallium nitride (GaN) ) The semiconductor layer is hexagonal. In this manufacturing method, the conductive substrate is an iron-nickel (Fe-Ni) alloy or a copper-tungsten (Cu-W) alloy. In this manufacturing method, the conductive adhesive is gold-tin (Au-Sn) solder or lead-tin (Pb-Sn) solder. A semiconductor light-emitting device according to the present invention is a semiconductor light-emitting device manufactured by the above-described method for manufacturing a semiconductor light-emitting device, and is provided on a stack composed of a gallium nitride-based semiconductor layer including a light-emitting layer and on one surface of the stack. A p-type electrode, an n-type electrode provided on the other surface of the laminate, and a conductive substrate bonded to one of the p-type electrode and the n-type electrode with a conductive adhesive. In this semiconductor light emitting device, the conductive substrate is an iron-nickel (Fe-Ni) alloy or a copper-tungsten (Cu-W) alloy. In the semiconductor light emitting device, the conductive adhesive is gold-tin (Au-Sn) solder or lead-tin (Pb-Sn) solder.
A semiconductor light emitting device according to the present invention includes a p-type GaN layer provided with a p-type electrode, a conductive substrate bonded to the p-type electrode with a conductive adhesive, and a GaN formed on the p-type GaN layer. A laminated structure of a semiconductor layer, or an n-type GaN layer provided with an n-type electrode, a conductive substrate bonded to the n-type electrode with a conductive adhesive, and formed on the n-type GaN layer It consists of a laminated structure of GaN-based semiconductor layers.

  In the semiconductor light emitting device of the present invention, the conductive substrate is an Fe—Ni alloy or a Cu—W alloy, and the conductive adhesive is Au—Sn solder or Pb—Sn solder.

  A method for manufacturing a semiconductor light emitting device according to the present invention includes a method of growing a stacked layer of a GaN-based semiconductor layer on a growth substrate of GaAs, InP, InAs, or GaP, and then forming an electrode surface provided on the surface of the stacked layer with a conductive adhesive. Bonded to a conductive substrate. Then, the growth substrate made of GaAs, InP, InAs or GaP is removed.

  The growth substrate is a cubic (111) substrate, and the GaN-based semiconductor layer is a hexagonal crystal. In particular, the growth substrate is GaAs (111) A, and the GaN-based semiconductor layer is hexagonal. The growth substrate is removed by wet etching with an ammonia-based etchant.

  The semiconductor light emitting device according to the present invention is bonded to a p-type gallium nitride layer provided with a p-type electrode or an n-type gallium nitride layer provided with an n-type electrode, and the p-type or n-type electrode with a conductive adhesive. A conductive substrate, and a gallium nitride based semiconductor layer including a light emitting layer grown on the p-type or n-type gallium nitride layer and on a surface opposite to the surface on which the p-type or n-type electrode is provided. It is comprised by the lamination | stacking which becomes.

  In the semiconductor light emitting device of the present invention, the conductive substrate is preferably an iron-nickel (Fe-Ni) alloy or a copper-tungsten (Cu-W) alloy.

  In the semiconductor light emitting device of the present invention, the conductive adhesive may be gold-tin solder or lead-tin solder.

  The method for manufacturing a semiconductor light emitting device according to the present invention includes a conductive adhesive comprising an electrode surface provided on a surface of a laminate composed of a gallium nitride based semiconductor layer including a light emitting layer grown on a growth substrate, and a conductive substrate. Then, the growth substrate is removed and manufactured.

  In the manufacturing method of the present invention, the growth substrate is preferably gallium arsenide (GaAs), indium phosphide (InP), indium arsenide (InAs), or gallium phosphide (GaP).

  In the manufacturing method of the present invention, the growth substrate is a cubic (111) substrate made of gallium arsenide (GaAs), indium phosphide (InP), indium arsenide (InAs), or gallium phosphide (GaP), and a gallium nitride based semiconductor It is preferred that the layer is hexagonal.

  In the manufacturing method of the present invention, the growth substrate is preferably a cubic (111) A substrate made of gallium arsenide (GaAs).

  In the manufacturing method of the present invention, the growth substrate may be removed by wet etching using an ammonia-based etchant.

  A semiconductor light-emitting device according to the present invention includes a stack composed of a gallium nitride-based semiconductor layer including a light-emitting layer, an electrode provided on the surface of the stack, and a conductive substrate bonded to the electrode with a conductive adhesive. .

  In the semiconductor light emitting device of the present invention, the conductive substrate is preferably an iron-nickel (Fe—Ni) alloy or a copper-tungsten (Cu—W) alloy.

  In the semiconductor light emitting device of the present invention, the conductive adhesive may be gold-tin (Au-Sn) solder or lead-tin (Pb-Sn) solder.

  As described above, according to the present invention, it is possible to provide a semiconductor light emitting device that emits light with little light absorption on the substrate, and can easily manufacture the semiconductor light emitting device.

It is sectional drawing which shows the structure of an epitaxial wafer until the time of etching removal of the GaAs substrate in an Example. It is sectional drawing which shows the structure of an epitaxial wafer until the time of producing a p-type electrode in an Example. It is sectional drawing which shows the structure of the epitaxial wafer until it adheres the p-type GaN layer side to the iron-nickel alloy in the Example. It is a figure which shows the outline | summary of the apparatus of an organometallic chloride vapor phase epitaxial method. It is sectional drawing which shows the structure of an epitaxial wafer until the time of producing an electrode on the GaAs substrate side in a comparative example. It is sectional drawing which shows the structure of an example of the blue semiconductor light-emitting device using a sapphire substrate.

  The description of the embodiment of the present invention relates to a blue and green light emitting element using a gallium nitride (GaN) based semiconductor and a method for manufacturing the same. The semiconductor light emitting device according to the embodiment of the present invention does not include an insulating layer in the structure of the light emitting device. Therefore, a complicated process is not required for electrode formation unlike the case where sapphire which is an insulating layer is used for a substrate. In addition, when a growth substrate using GaAs or the like having a smaller band gap than the light emitting layer of the GaN-based semiconductor layer is used, the GaN-based semiconductor layer including the light-emitting layer is stacked on the conductive substrate using a conductive adhesive. If the growth substrate on which the laminate is grown is removed after bonding, light is not absorbed by the growth substrate, and good light emission is obtained.

  When an Fe—Ni alloy or Cu—W alloy having excellent conductivity and thermal conductivity is used as the conductive substrate, light emission with low power consumption is possible and heat release is improved.

  For the conductive adhesive, an Au—Sn solder (for example, a commercial product having a melting point of 280 ° C. (280 ° C.)) or a Pb—Sn solder (for example, a melting point of 280 ° C. (280 ° C.)) is used. When a commercially available product is used), the temperature can be increased to about 200 ° C. (200 degrees Celsius) for electrode formation, and a good electrode can be easily produced.

  When GaAs, InP, InAs, or GaP is used as a growth substrate on which a stack of GaN-based semiconductor layers is formed, the growth substrate can be easily removed by etching. Further, when a cubic (111) substrate is used, hexagonal GaN can be epitaxially grown.

  Furthermore, if a GaAs (111) A substrate (a GaAs substrate in which all of the (111) surface is Ga) is used, a good stack of GaN-based semiconductor layers can be produced.

  Etching the GaAs substrate with an ammonia-based etchant makes it easy to remove the GaAs substrate by etching and does not damage the GaN-based semiconductor layer and its stack. Is preferred.

  Next, examples that specifically show how the present invention is implemented will be described.

(Example) Organometallic chloride vapor phase epitaxial method (FIG. 4 shows an outline of the apparatus, in which a GaAs (111) A substrate 1 is placed in a reaction chamber 54 made of quartz. 52, an exhaust port 53, and a resistance heater 55. The apparatus is the same as the apparatus disclosed in Japanese Patent Laid-Open No. 8-181070 disclosed by the present inventor. A GaN buffer layer 2 having a thickness of 100 nm and an n-type GaN layer having a thickness of 2 μm (μm) and a carrier concentration of 1 × 10 ¹⁹ (cm −3) on a GaAs (111) A substrate 1 having a micrometer (μm). 3. From an InGaN light-emitting layer 4 having a thickness of 0.1 μm (μm) and a p-type GaN layer 5 having a thickness of 0.5 μm and a carrier concentration of 1 × 10 ¹⁸ (cm ⁻³ ) and a thickness of 0.5 μm (μm) A GaN-based semiconductor layer stack was grown in this order.

  An electrode 6 is produced by depositing Ni and Au in this order on the p-type GaN layer 5 which is the outermost surface of the GaN-based semiconductor layer, and alloyed at 400 ° C. (400 ° C.) for 5 minutes. gave. FIG. 2 shows a cross section of an epitaxial wafer composed of a GaAs (111) A substrate 1, a laminate composed of a GaN-based semiconductor layer, and an electrode 6.

Thereafter, using a commercially available Au—Sn solder 7 having a melting point of 280 ° C. (280 ° C.), an Fe—Ni alloy (46% by weight of Ni is 46% by weight) on the electrode 6 on the p-type GaN layer 5 on the outermost surface The remainder is made of Fe and inevitable impurities). (Figure 3)
The epitaxial wafer shown in FIG. 3 was immersed for 90 minutes (wet etching) in a solution maintained at 25 ° C. (25 ° C.) by mixing ammonia water and hydrogen peroxide water in a ratio of 1: 2 to obtain GaAs (111) A. Only the substrate 1 was removed to obtain the structure of FIG.

  An indium (In) electrode is formed on the GaN buffer layer 2 on the outermost surface of the structure of FIG. 1 at 200 ° C. (200 degrees Celsius), and a current flows between the electrode 6 formed by depositing Ni and Au in this order. As a result, blue light was emitted. It should be noted that even if a sintered alloy of 80% by weight and 20% Cu is used instead of the Fe-Ni alloy consisting of 46% by weight of Ni and the balance being Fe and inevitable impurities, the same blue color will be obtained. Emitted light.

  (Comparative example) In order to observe the difference in emission intensity due to light absorption of two different types of substrates, an Fe-Ni alloy substrate and a GaAs substrate, the cross-sections of the epitaxial wafer shown in FIG. 5 are compared. As an example.

  That is, an electrode 9 having a laminated structure composed of an AuGeNi alloy layer, a Ni layer, and an Au layer is formed on the GaAs (111) A substrate 1 side in the structure of FIG. 2, and the electrode 9 is deposited in the order of Ni and Au. When an electric current was passed between the electrode 6 and the electrode 6, blue light was emitted. However, the emission intensity of the comparative example was as weak as about 70% of the emission intensity of the above example.

1: GaAs (111) A substrate 2: GaN buffer layer 3: n-type GaN layer 4: InGaN light emitting layer 5: p-type GaN layer 6: Ni and Au deposited in this order 7: Au-Sn solder 8: Fe-Ni alloy conductive substrate 9: electrode having a laminated structure composed of an AuGeNi alloy layer, a Ni layer, and an Au layer

Claims (10)

  After the electrode surface provided on the surface of the stack composed of the gallium nitride (GaN) -based semiconductor layer including the light emitting layer grown on the growth substrate and the conductive substrate are bonded using a conductive adhesive, the growth is performed. A method for producing a semiconductor light emitting device, comprising: removing the substrate for manufacture.   2. The method of manufacturing a semiconductor light emitting device according to claim 1, wherein a band gap of the growth substrate is smaller than a band gap of the light emitting layer.   The growth substrate is a cubic (111) substrate made of gallium arsenide (GaAs), indium phosphide (InP), indium arsenide (InAs), or gallium phosphide (GaP), and the gallium nitride (GaN) based semiconductor layer is The method for manufacturing a semiconductor light-emitting element according to claim 1, wherein the method is a hexagonal crystal.   3. The method for manufacturing a semiconductor light-emitting element according to claim 1, wherein the growth substrate is removed by wet etching using an ammonia-based etchant.   5. The growth substrate according to claim 1, wherein the growth substrate is a cubic (111) substrate, and the gallium nitride (GaN) -based semiconductor layer is a hexagonal crystal. A method for manufacturing a semiconductor light emitting device.   The conductive substrate is an iron-nickel (Fe-Ni) alloy or a copper-tungsten (Cu-W) alloy, or any one of claims 1, 2, 4, and 5. The manufacturing method of the semiconductor light-emitting device described in the item.   7. The semiconductor light emitting device according to claim 1, wherein the conductive adhesive is gold-tin (Au—Sn) solder or lead-tin (Pb—Sn) solder. 8. Device manufacturing method.   A semiconductor light-emitting device manufactured by the method for manufacturing a semiconductor light-emitting device according to claim 1, wherein the stack includes a gallium nitride-based semiconductor layer including a light-emitting layer, and the stack A p-type electrode provided on one surface of the electrode, an n-type electrode provided on the other surface of the laminate, and a conductive material bonded to one of the p-type electrode and the n-type electrode with a conductive adhesive. A semiconductor light emitting device comprising a conductive substrate.   9. The semiconductor light emitting device according to claim 8, wherein the conductive substrate is an iron-nickel (Fe-Ni) alloy or a copper-tungsten (Cu-W) alloy.   The semiconductor light emitting device according to claim 8 or 9, wherein the conductive adhesive is gold-tin (Au-Sn) solder or lead-tin (Pb-Sn) solder.

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