JP2005303285A - Group iii nitride semiconductor light emitting element, its manufacturing method, and led lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a group III nitride semiconductor light emitting element that is provided with a mechanically supporting function, such as the substrate and, at the same time, can be improved in luminous efficiency by reducing the absorption of ultraviolet rays having short wavelengths. <P>SOLUTION: The group III nitride semiconductor light emitting element comprises a laminated structure 11 formed by laminating at least two group III nitride semiconductor layers 104 and 106 having mutually different electric conduction types and a light emitting layer 105 consisting of a group III nitride semiconductor provided in between the layers 104 and 106. The light emitting element has a plate-shaped body 111 which is formed on a surface exposed after a crystalline substrate used for providing the laminated structure 11 is removed and composed of a transparent material to the light radiated from the light emitting layer 105. The light emitting element is constituted so that the light radiated from the light emitting layer 105 may be taken out from the plate-shaped body 111. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a group III nitride comprising a laminated structure in which at least two group III nitride semiconductor layers having different electrical conductivity types and a light emitting layer made of a group III nitride semiconductor provided therebetween are laminated. The present invention relates to a semiconductor light emitting device, a manufacturing method thereof, and an LED lamp.

Conventionally, Group III nitride semiconductor light emitting devices such as light emitting diodes (LEDs) and laser diodes (LDs) that emit blue or green band short-wavelength light are, for example, gallium nitride and indium (compositional formula Ga _Y In _Z N: 0 ≦ Y, Z ≦ 1, Y + Z = 1) is used as the light emitting layer (see, for example, Patent Document 1). The light emitting section is configured by arranging clad layers made of two group III nitride semiconductors having different electrical conductivity types on both sides of the light emitting layer. A clad layer for forming such a light emitting part having a double heterojunction (double hetero: DH) structure is, for example, aluminum nitride gallium (compositional formula Al _x Ga _y N: 0 ≦ X, Y ≦ 1, X + Y). = 1).
Japanese Patent Publication No.55-3834

A pn-junction type DH group III nitride semiconductor light-emitting device having a DH structure light-emitting portion in which a light-emitting layer is sandwiched between an n-type cladding layer and a p-type cladding layer as described above is configured. Conventionally, a laminated structure for this purpose has been formed exclusively using sapphire (α-Al ₂ O ₃ single crystal) or silicon carbide (SiC) single crystal as a substrate. This is because it has optical transparency capable of transmitting light emitted from the light emitting layer and has heat resistance capable of withstanding crystal growth of a group III nitride semiconductor layer requiring high temperature. The conventional group III nitride semiconductor light-emitting device is a plate-like substrate that mechanically supports the laminated structure even after the device-forming process, using the substrate as described above for forming the laminated structure for light-emitting devices. Usually, it is made to remain as a body.

  However, for example, a group III nitride semiconductor light-emitting device in which a substrate made of sapphire crystal or a SiC crystal substrate remains is suitable for maintaining the mechanical support of the laminated structure, but for short-wavelength ultraviolet light. Since light absorption occurs, the disadvantage is that the luminous efficiency is lowered.

  The present invention has been made in view of the above, and has a mechanical support function such as a substrate, can reduce light absorption with respect to short-wave ultraviolet light, and can improve luminous efficiency. It is an object of the present invention to provide a group III nitride semiconductor light emitting device, a manufacturing method thereof, and an LED lamp.

  1) In order to achieve the above object, the first invention includes at least two group III nitride semiconductor layers having different electrical conductivity types, and a light emitting layer made of a group III nitride semiconductor provided therebetween. In a group III nitride semiconductor light-emitting device composed of a stacked structure in which the stacked structures are stacked, the light emitted from the light-emitting layer formed on the exposed surface after removing the crystal substrate used to provide the stacked structure On the other hand, it has a plate-like body made of a transparent material, and is configured such that light emitted from the light emitting layer is extracted from the plate-like body.

  2) The second invention is characterized in that, in addition to the configuration of the invention described in the above item 1), the plate-like body is glass.

  3) In the third aspect of the invention, in addition to the configuration of the invention described in the above item 1) or 2), the removal of the crystal substrate from the laminated structure is performed by a bonding interface region between the laminated structure and the crystal substrate. It is characterized by being performed by irradiating with laser light.

  4) In the fourth aspect of the invention, in addition to the configuration of the invention described in any one of items 1) to 3), an ohmic electrode is provided on the side opposite to the plate-like body of the laminated structure. It is characterized by that.

  5) The fifth invention is characterized in that a metal reflective film is provided on the surface of the ohmic electrode in addition to the configuration of the invention described in the above item 4).

  6) The sixth invention is characterized in that, in addition to the configuration of the invention described in the above item 5), a gold film is provided on the surface of the metal reflective film.

  7) The seventh invention comprises a laminated structure in which at least two group III nitride semiconductor layers having different electrical conductivity types and a light emitting layer made of a group III nitride semiconductor provided therebetween are laminated. In the method of manufacturing a group III nitride semiconductor light emitting device, the crystal substrate used for providing the stacked structure is removed, and the exposed surface exposed by the removal of the crystal substrate is exposed to light emitted from the light emitting layer. A plate-like body made of a transparent material is formed, and light emitted from the light emitting layer is extracted from the plate-like body.

  8) The eighth invention is an LED lamp, characterized in that it comprises the group III nitride semiconductor light-emitting device according to any one of items 1) to 6).

  9) The ninth invention is characterized in that, in addition to the configuration of the invention described in the above item 8), it is mounted in a flip type on a submount mainly composed of Si.

  In the present invention, a plate-like body made of a material transparent to the light emitted from the light emitting layer is formed on the exposed surface after removing the crystal substrate used for providing the laminated structure. In addition to being mechanically supported by the body, absorption of light with respect to short-wave ultraviolet rays can be reduced, and luminous efficiency can be improved.

  In addition, a material having a thermal expansion coefficient substantially the same as the thermal expansion coefficient of the laminated structure can be selected for the plate-like body. Therefore, even if an electric current is passed for a long time, the laminated structure is caused by thermal stress. Cracks do not occur and reliability can be improved.

  Further, since the LED lamp can be obtained simply by mounting the light emitting element on the submount, the LED lamp can be easily manufactured.

  Embodiments of the present invention will be described in detail below.

  The group III nitride semiconductor light-emitting device of the present invention includes (a) a first group III nitride semiconductor layer of a first conductivity type formed on a crystal substrate, and (b) a second group of second conductivity type. A laminated structure for a light-emitting device, comprising: a second group III nitride semiconductor layer; and (c) a light emitting layer made of a group III nitride semiconductor sandwiched between the first and second group III nitride semiconductors. Consists of. The first and second group III nitride semiconductor layers have functions as a cladding layer and a contact layer.

As a crystal substrate for forming a stacked structure, an oxide single crystal such as sapphire or lithium gallium oxide (composition formula LiGaO ₂ ), a 3C crystal type cubic single crystal silicon carbide (3C-SiC), 4H, or 6H crystal type hexagonal single crystal SiC (4H-SiC, 6H-SiC), silicon (Si) single crystal (silicon), gallium phosphide (GaP) and gallium arsenide (GaAs) III-V group semiconductor single crystals Etc. can be used.

  When the first group III nitride semiconductor layer forming the stacked structure is provided on a crystal substrate that is not in lattice matching relationship with the first group III nitride semiconductor layer, the first group III nitride semiconductor layer is provided through a buffer layer that relaxes lattice mismatch. For example, when a GaN-based first group III nitride semiconductor layer is grown on a sapphire substrate, a seeding process (SP) method (see Japanese Patent Application Laid-Open No. 2003-243302) is provided on the substrate surface. A first group III nitride semiconductor layer is stacked via the GaN buffer layer. Even if the low-temperature buffer layer is made of AlN instead of GaN, it is effective to alleviate the lattice mismatch with the substrate. In the case of AlN, the low-temperature buffer layer has a thickness of 1 nm to 100 nm, preferably 2 nm to 50 nm, more preferably 2 nm to 5 nm.

  The surface of the low-temperature buffer layer is preferably flat rather than having fine irregularities. For example, the surface roughness Ra is preferably 0.10 μm or less, preferably 0.05 μm or less. Such a low-temperature low-temperature buffer layer having a small roughness can be obtained by providing a single crystal layer at the interface with the crystal substrate during growth at a low temperature of 350 ° C. to 450 ° C., for example. The surface roughness is obtained using a measuring instrument such as an atomic force microscope (AFM). A low-temperature buffer layer having a flat surface with less roughness is advantageous for laminating an upper layer having excellent surface flatness. For example, an underlying layer having a smooth and flat surface can be grown on the surface of a GaN low-temperature buffer layer having a small roughness.

  An underlayer having a flat surface, for example, a GaN layer, provided on the buffer layer can contribute to providing a group III nitride semiconductor layer of the first or second electrical conductivity type having excellent surface flatness. Here, if the first group III nitride semiconductor layer is an n-type layer, the second group III nitride semiconductor layer is a p-type layer of the opposite electrical conductivity type. The layer thickness of the underlying layer, which is advantageous for providing the first and second group III nitride semiconductor layers having excellent surface flatness, is 0.5 μm or more and 5 μm or less, taking the case of a GaN layer as an example. Yes, preferably in the range of 1 μm or more and 3 μm or less. The first or second group III nitride semiconductor layer having a flat surface can be used as an n-type or p-type clad layer convenient for stacking a quantum well structure composed of an extremely thin well layer having excellent flatness. It can also be used as an n-type or p-type contact layer that is convenient for forming input and output electrodes having excellent adhesion.

As the first and second group III nitride semiconductor layers, undoped layers to which impurities are not intentionally added can be used. In addition, an n-type or p-type group III nitride semiconductor layer to which impurities are intentionally added (doping) in order to control electric conductivity type, carrier concentration, or resistance value can be used. The first and second group III nitride semiconductor layers doped with n-type or p-type impurities so that the atomic concentration in the layer is 1 × 10 ¹⁸ cm ⁻³ or more and 5 × 10 ¹⁹ cm ⁻³ or less are provided. For example, a clad layer for obtaining a light-emitting element having a low forward voltage and operation reliability is suitable for the configuration. The first or second group III nitride semiconductor layer to be the cladding layer needs to be composed of a material having a larger band gap than the constituent material of the light emitting layer, but is necessarily composed of the same group III nitride semiconductor material. There is no need. For example, the n-type cladding layer is composed of n-type Ga _Y In _ZN (0 ≦ Y, Z ≦ 1, Y + Z = 1), and the p-type cladding layer is p-type Al _X Ga _Y N (0 ≦ X, Y ≦ 1, X + Y = 1). If a first or second electrically conductive clad layer made of a group III nitride semiconductor of a different material is used, an asymmetrical light emitting portion can be configured with respect to the light emitting layer in terms of a band structure.

Within the above atomic concentration range, the first and second group III nitride semiconductor layers containing impurities at a high concentration and having a low resistance are useful as contact layers. A low-resistance group III nitride semiconductor layer having a carrier concentration of 1 × 10 ¹⁸ cm ⁻³ or more is particularly advantageous for forming an ohmic electrode having a low contact resistance. Examples of n-type impurities that can be used to obtain a low-resistance n-type group III nitride semiconductor layer include Group IV elements such as silicon (Si) and germanium (Ge), and Group VI elements such as selenium (Se). . As the p-type impurity, a Group II element such as magnesium (Mg) or beryllium (Be) can be used. The thickness of the contact layer is preferably equal to or greater than the depth at which the material constituting the ohmic electrode diffuses and penetrates. When an ohmic electrode is formed by performing alloying (alloying) heat treatment, it is suitable that the thickness be equal to or greater than the depth of the so-called alloy front. For example, 10 nm or more is suitable.

The light emitting layer provided between the first and second group III nitride semiconductor layers is made of, for example, gallium nitride indium (compositional formula Ga _Y In _Z N: 0 ≦ Y, Z ≦ 1, Y + Z = 1). Further, for example, nitride gallium phosphide (compositional formula _{GaN 1-a P a: 0} ≦ a <1) Al X Ga containing nitrogen (N), such as a Group V element different from nitrogen _Y In _Z N _{1 -a} M _a (0 ≦ X, Y, Z ≦ 1, X + Y + Z = 1, symbol M represents a group V element other than nitrogen, and 0 ≦ a <1). The light emitting layer may be composed of a single layer (SQW) or a multiple quantum well structure (MQW). In the case where the well layer having the quantum well structure is made of, for example, Ga _Y In _Z N, the indium (In) composition ratio (= Z) is adjusted in view of the desired emission wavelength. The longer the wavelength is emitted, the greater the indium composition ratio. The total layer thickness of the light emitting layer having a multiple quantum well structure having Ga _Y In _Z N as a well layer is preferably 100 nm or more and 500 nm or less.

In the quantum well structure of the light emitting layer, a layer bonded to the first or second group III nitride semiconductor layer can be formed as a barrier layer or a well layer. The starting end (lowermost bottom layer) of the quantum well structure may be either a barrier layer or a well layer. Similarly, the end (outermost layer) of the quantum well structure may be either a barrier layer or a well layer. The start layer and the end layer may have different compositions. The quantum well structure composed of a well layer with excellent crystallinity due to undoping and a barrier layer doped with impurities avoids adverse effects due to the piezo effect, is superior in strength, and has a stable emission wavelength. This contributes to obtaining a Group III nitride semiconductor light emitting device. Well layer and the barrier _{layer, Ga Y In Z N (0} ≦ Y, Z ≦ 1, Y + Z = 1) was _{added, GaN 1-a P a (} 0 ≦ a <1) , such as Al _X Ga _Y In _Z N _1-a M _a (0 ≦ X, Y, Z ≦ 1, X + Y + Z = 1, symbol M represents a group V element other than nitrogen, and 0 ≦ a <1).

  The III-nitride semiconductor layers constituting the laminated structure are formed by, for example, metal organic chemical vapor deposition (MOCVD) means, hydride vapor deposition (VPE) means, and molecular beam epitaxial (MBE) means. It can be grown by vapor phase growth means. In order to obtain a layer having a wide film thickness on the order of μm suitable for the first or second group III nitride semiconductor layer from several nm forming the well layer of the quantum well structure light emitting layer, MOCVD means or MBE means Is suitable. In particular, the MOVPE means is suitable for vapor-phase growth of a group III nitride semiconductor layer containing highly volatile arsenic (As) or phosphorus (P) other than nitrogen. Normal pressure (substantially atmospheric pressure) or reduced pressure MOCVD means can be used.

  In the present invention, since the crystal substrate used for forming the laminated structure for light emitting device is removed, it is not necessary to use an optically transparent crystal as the substrate. Rather, since it is necessary to remove the existing substrate (the crystal substrate used for forming the laminated structure), etching means by a dry method such as a wet method or a high-frequency plasma etching method, or a laser (laser) The substrate is preferably a crystal that can be easily and easily peeled off by means depending on the irradiation method or the like. A crystal substrate having a coefficient of thermal expansion that is significantly different from the constituent layers of the laminated structure is convenient for peeling by the laser irradiation means.

  Further, in the present invention, after removing the pre-existing crystal substrate on the outermost layer of the laminated structure, a plate-like body having mechanical strength is pasted in order to reinforce the decrease in the mechanical support force of the laminated structure. Provide. Examples of the plate-like body to be attached include a plate-like body made of a material transparent to light emitted from the light emitting layer, for example, glass.

The lamination structure and the plate-like body can be bonded easily by preliminarily washing the surface of the laminated structure to be bonded or the surface of the plate-like body to be bonded to the lamination structure. For example, for laminating the plate-shaped body and a group III nitride semiconductor layer (stacked structure) to the stubborn, on attachment, for example, 1kg / cm ² ~5kg / cm ² if pressurized with external pressure, or 500 Bonding can be facilitated by heating to a high temperature of 1000 ° C. to 1000 ° C., or by applying an anodic bonding method by applying temperature, pressure and voltage. In this case, if a layer such as GaN, AlN, or GaAlN that strengthens the bonding is formed between the plate-like body and the light emitting layer, the bonding can be performed without adversely affecting the characteristics.

  It is also possible to bond a plate-like body after forming an adhesive layer such as a silicone resin on the surface.

  In order to remove the substrate used for forming the laminated structure, polishing means or peeling means can be used. For example, the sapphire substrate can be polished using polishing powder mainly composed of silica, alumina, or diamond fine powder.

In order to peel off the crystal substrate used to form the laminated structure, laser irradiation means is suitable. As a laser beam suitable for irradiation for peeling, a pulse laser beam, a carbon dioxide (CO ₂ ) laser beam, an excimer laser beam, or the like can be used. In particular, an excimer laser using argon fluoride (ArF), krypton fluoride (KrF), or the like as an excitation gas is preferably used. The wavelength of the laser light is preferably 193 nm or 248 nm. In the case where the crystal substrate is peeled off by irradiation with laser light, if the thickness of the crystal substrate is large, the laser light is easily absorbed, and the region to be peeled off efficiently cannot be heated. Therefore, it is appropriate that the thickness of the crystal substrate is set to 100 μm to 300 μm in order to efficiently separate the laminated structure and the crystal substrate by irradiating the laser beam. In addition, when the surface of the crystal substrate has irregularities, fine scratches, etc., the absorption of the laser beam is changed, and uneven peeling tends to occur.

  As described above, in the embodiment of the present invention, a plate-like material made of a material transparent to light emitted from the light emitting layer is formed on the exposed surface after removing the crystal substrate used for providing the laminated structure. Since the body is formed, it is mechanically supported by the plate-like body, absorption of light with respect to short wavelength ultraviolet rays can be reduced, and luminous efficiency can be improved.

  In addition, a material having a thermal expansion coefficient substantially the same as the thermal expansion coefficient of the laminated structure can be selected for the plate-like body. Therefore, even if an electric current is passed for a long time, the laminated structure is caused by thermal stress. Cracks do not occur and reliability can be improved.

  In the above description, the crystal substrate used for forming the laminated structure is completely removed to provide a plate-like body, but this crystal substrate does not necessarily need to be completely removed, and the thickness is You may stop to the extent to make it thin.

  By reducing the thickness of the crystal substrate used for forming the laminated structure, it is possible to reduce the absorption of light transmitted from the crystal substrate, and it is excellent in the efficiency of extracting light emitted to the outside. Thus, a group III nitride semiconductor light emitting device having excellent electrostatic withstand voltage can be obtained. For this purpose, it is preferable to use an optically transparent n-type or p-type conductive single crystal as a substrate. The crystal substrate to be left has both the function of mechanically supporting the laminated structure and the function of transmitting light emitted from the light emitting layer to the outside. If the thickness of the remaining crystal substrate is made thinner, the transmittance of light emission increases, which is advantageous for obtaining a group III nitride semiconductor light emitting device having excellent efficiency of extracting light emitted to the outside. On the other hand, the effect of supporting the laminated structure of the crystal substrate is reduced with the thinning. Therefore, the thickness of the remaining crystal substrate is suitably 100 μm to 300 μm from the balance of both.

  The contents of the present invention will be described by taking, as an example, a case where a group III nitride semiconductor light emitting device is constructed by sticking a glass substrate to the outermost layer of the laminated structure as a plate-like body.

  FIG. 1 schematically shows a cross-sectional structure of a laminated structure formed on a sapphire substrate, and FIG. 2 schematically shows a cross-sectional structure of an LED according to the present invention prepared by chipping from the laminated structure of FIG. FIG. 3 is a plan view of the LED, and FIG. 4 is a cross-sectional view showing an LED lamp configured by mounting the LED.

  First, as shown in FIG. 1, an aluminum nitride (AlN) layer 101 is formed on a (0001) crystal plane of an electrically insulating sapphire substrate 100 having a thickness of about 350 μm by using a seeding process (SP) means. The film was formed at 900 ° C. by a general low pressure MOCVD method. The layer thickness of the AlN layer 101 was 5 nm. A buffer layer 102 made of gallium nitride (GaN) having a thickness of 18 nm at 1050 ° C. was formed on the AlN layer 101.

On the GaN buffer layer 102, an n-type aluminum nitride / gallium mixed crystal (Al) having an aluminum composition ratio of 0.01 so that the atomic concentration in the layer of silicon (Si) is 1 × 10 ¹⁸ cm ^−3. _An n-type contact layer 103 made of _0.01 Ga _0.99 N) was formed. The contact layer 103 was grown at 1050 ° C. by a general low pressure MOCVD method. The layer thickness of the n-type contact layer 103 was about 2.5 μm.

On the n-type Al _0.01 Ga _0.99 N contact layer 103, an n-type cladding layer 104 made of n-type Al _0.10 Ga _0.90 N was laminated. The n-type cladding layer 104 was formed by doping Si so that the atomic concentration in the layer was 1 × 10 ¹⁸ cm ⁻³ . The layer thickness of the n-type cladding layer 104 grown by a general low pressure MOCVD method was about 0.5 μm.

On the n-type Al _0.10 Ga _0.90 N cladding layer 104, an n-type multi-quantum well structure composed of a barrier layer made of n-type Al _X Ga _Y N and a well layer made of n-type Ga _Y In _Z N is used. The type light emitting layer 105 was laminated. The indium (In) composition ratio (= Z) of the well layer was adjusted so that ultraviolet light having a wavelength of 360 nm to 370 nm was emitted from the quantum well structure. The quantum well structure was configured with the well layer having a thickness of about 5 nm and the barrier layer having a thickness of 15 nm.

On the light emitting layer 105 having a multiple quantum well structure, a p-type Al _X1 Ga _Y1 N clad layer 106 having a layer thickness of 2.5 nm was formed by intentionally adding (doping) Mg as a p-type impurity. The aluminum composition ratio (= X ₁ ) was about 0.10 (= 10%). Mg was doped in the same layer 106 so that the atomic concentration was about 5 × 10 ¹⁸ . On the p-type cladding layer 106, a p-type contact layer 107 made of Al _X2 Ga _Y2 N (X ₁ > X ₂ ≧ 0) having a smaller Al composition ratio doped with Mg was formed. The atomic concentration of Mg inside the contact layer 107 was about 2 × 10 ¹⁹ / cm ⁻³ .

  A thin film of platinum (Pt) was formed as a p-type ohmic electrode film 108 on the surface of the p-type contact layer 107 by a general high-frequency sputtering means. A metal reflective film 109 is provided on the p-type ohmic electrode film 108 in order to reflect light emitted from the light emitting layer 105 having the multiple quantum well structure to the crystal substrate 100 side. The metal reflective film 109 was composed of a rhodium (Rh) film.

  An n-type ohmic electrode 113 made of Cr / Ti / Au was formed on the n-type contact layer 103 on the surface covered with a mask and dug by a dry etching process (FIG. 3). The outermost layer of the n-type ohmic electrode 113 is gold (Au).

  A gold film 110 for bonding was formed on the metal reflective film 109, and the laminated structure 11 from the sapphire substrate 100 to the metal reflective film 109 was configured as a previous stage.

  Thereafter, the back surface of the sapphire substrate 100 that had mechanically supported the multilayer structure 11 until now was ground. The back surface of the sapphire substrate 100 was polished to a thickness of 130 μm to 150 μm using colloidal silica containing silicon oxide fine particles having an average particle diameter of 0.5 μm. By this polishing, the thickness of the sapphire substrate 100 was reduced to 210 ± 10 μm.

  After the back surface of the sapphire substrate 100 was ground, glass was bonded to the opposite metal reflective film 109 using a water-soluble adhesive, and the mechanical support force of the laminated structure 11 was temporarily reinforced.

  An excimer laser beam having a wavelength of 248 nm was irradiated from the surface of the thinly polished sapphire substrate 100 so as to focus on the bonding interface between the sapphire substrate 100 and the GaN buffer layer 102. Thus, using the difference in thermal expansion coefficient between the sapphire substrate 100 and the laminated structure 11 thereon, sapphire that has already been thinned by polishing from the AlN layer 101 and the GaN buffer layer 102 portion. The substrate 100 was peeled off.

  On the surface, phosphor glass that emits three colors of RGB to ultraviolet light near 370 nm was bonded as a plate-like body 111 using an anodic bonding method. The voltage in the anodic bonding method was 340 V, and good bonding was possible at a relatively low temperature of about 300 ° C. As a method of dispersing the phosphor in the glass, a method of applying the phosphor on the glass surface by a spin coating method was used. As another method of dispersing fine powder in glass, a method of dispersing fine powder of 10 nm or less in glass by a sol-gel method can prevent the fine powder from agglomerating, and an extremely good product can be manufactured.

  Thereafter, the glass temporarily provided on the surface side of the metal reflective film 109 of the laminated structure 11 was removed, and the electrode surface was washed to complete the LED wafer.

  Next, a split groove for element division was provided on the semiconductor side by a general laser scribing method. Thereafter, a mechanical pressure is applied to the groove using a general breaker, and an individual group III nitride semiconductor light-emitting element (chip) 12 (hereinafter referred to as a square) having a substantially square shape in plan view and having a side length of about 350 μm , "LED12"). As a result, the sapphire substrate 100 is deleted, and a white glass group III nitride having a pn junction type DH structure in which the fluorescent glass body of the plate-like body 111 affixed to the laminated structure 11 bears the mechanical support of the laminated structure 11. A physical semiconductor LED 12 (FIGS. 2 and 3) was completed.

  Since the LED 12 formed an element over the entire surface using the affixed plate-like body 111, a high-luminance white LED element with extremely good color rendering properties could be produced.

  Next, the LED lamp 10 was constructed using the LED 12. A p-type ohmic electrode 108 (metal reflective film 109, gold film 110) and an n-type ohmic electrode 113 provided on the surface side of the LED 12 (laminated structure 11) are placed on an Si submount 23 as shown in FIG. Ball bumps 21 were formed and mounted. In addition, the circuit configuration is such that an element driving current can flow between the p-type ohmic electrode 108 (the metal reflection film 109 and the gold film 110) and the n-type ohmic electrode 113.

  Since each surface of the p-type ohmic electrode 108 (the metal reflection film 109 and the gold film 110) and the n-type ohmic electrode 113 is a gold (Au) film, bonding can be easily performed. Then, it sealed with the epoxy resin 22 for the semiconductor sealing use which contained the inhibitor for preventing the deterioration resulting from an ultraviolet-ray, and the light emitting diode (LED) lamp 10 was completed.

  When an element driving current was passed in the forward direction between the n-type ohmic electrode 113 and the p-type ohmic electrode 108 (metal reflection film 109, gold film 110), the driving current could be diffused in a wide area in the light emitting layer 105 in a planar manner. . When the LED 12 was caused to emit light with a device drive current of 20 mA, the light output reached about 20 lumens / watt (lm / W) when measured for ultraviolet light having a wavelength of about 370 nm. Further, the forward voltage Vf when the forward current was 20 mA was a low value of about 3.4V.

  As described above, the plate-like body 111 made of a material transparent to the light emitted from the light emitting layer 105 is formed on the exposed surface after removing the sapphire substrate 100 used to provide the laminated structure 11. In addition to being mechanically supported by the plate-like body 111, absorption of light with respect to ultraviolet rays having a short wavelength can be reduced, and luminous efficiency can be improved.

  Further, the driving current can be diffused in a wide area in the light emitting layer 105 in a planar manner, and the light emitting area is expanded, resulting in an LED having a strong light emission output.

  In addition, a material having a thermal expansion coefficient substantially the same as the thermal expansion coefficient of the laminated structure 11 can be selected for the plate-like body 111. Therefore, even if a current is passed for a long time, thermal stress is applied to the laminated structure 11. As a result, no cracks were caused and the reliability was improved.

  Moreover, since LED12 used the glass with a refractive index of 1.5 as the plate-shaped body 111, the light extraction efficiency increased, and an element with extremely good light emission characteristics was obtained. That is, the refractive index 1.5 of the plate-like body 111 is an intermediate value between GaN which is the main material of the laminated structure 11 and epoxy resin, and the interface between the plate-like body 111 and GaN (laminated structure 11), Moreover, since reflection at the interface between the plate-like body 111 and the epoxy resin 22 is reduced, the light extraction efficiency can be improved.

  If the LED 12 having the structure of the present invention is used, a suitable material can be selected for various characteristics such as light extraction efficiency, multicolor emission, and electrostatic countermeasures without being limited by the characteristics of the substrate used for growth. A light emitting element can be completed. In addition, since the LED lamp 10 was covered with a fluorescent glass having a high resistance to ultraviolet rays, a reliable lamp with little resin deterioration was obtained.

It is a figure which shows typically the cross-section of the laminated structure formed on the sapphire substrate. It is a figure which shows typically the cross-sectional structure of LED which concerns on this invention produced by chip-izing from the laminated structure of FIG. It is a top view of LED. It is sectional drawing which shows the LED lamp comprised by mounting LED.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 LED lamp 11 Laminated structure 100 Sapphire substrate 101 AlN layer 102 GaN buffer layer 103 GaN contact layer 104 n-type clad layer 105 Quantum well structure light emitting layer 106 p-type clad layer 107 p-type contact layer 108 p-type ohmic electrode 109 Metal reflection Film 110 Gold film 111 Plate 113 N-type ohmic electrode 21 Au ball bump 22 Epoxy resin 23 Si submount

Claims (9)

In a group III nitride semiconductor light-emitting device having a laminated structure in which at least two group III nitride semiconductor layers having different electrical conductivity types and a light emitting layer made of a group III nitride semiconductor provided therebetween are stacked ,
Having a plate-like body made of a material transparent to the light emitted from the light emitting layer, formed on the exposed surface after removing the crystal substrate used to provide the laminated structure,
The light emitted from the light emitting layer is configured to be extracted from the plate-like body,
A group III nitride semiconductor light emitting device characterized by the above.   The group III nitride semiconductor light-emitting device according to claim 1, wherein the plate-like body is glass.   3. The group III nitride semiconductor light-emitting element according to claim 1, wherein the removal of the crystal substrate from the multilayer structure is performed by irradiating a laser beam to a junction interface region between the multilayer structure and the crystal substrate.   The group III nitride semiconductor light-emitting device according to any one of claims 1 to 3, wherein an ohmic electrode is provided on a side opposite to the plate-like body of the multilayer structure.   The group III nitride semiconductor light-emitting device according to claim 4, wherein a metal reflective film is provided on a surface of the ohmic electrode.   The group III nitride semiconductor light-emitting device according to claim 5, wherein a gold film is provided on a surface of the metal reflective film. A group III nitride semiconductor light-emitting device having a laminated structure in which at least two group III nitride semiconductor layers having different electrical conductivity types and a light emitting layer made of a group III nitride semiconductor provided therebetween is laminated In the manufacturing method,
Removing the crystal substrate used to provide the laminated structure,
On the exposed surface exposed by removing the crystal substrate, a plate-like body made of a material transparent to the light emitted from the light emitting layer is formed,
The light emitted from the light emitting layer is extracted from the plate-like body.
A method for producing a Group III nitride semiconductor light-emitting device.   An LED lamp comprising the group III nitride semiconductor light-emitting device according to any one of claims 1 to 6.   The LED lamp according to claim 8, wherein the LED lamp is mounted in a flip type on a submount mainly composed of Si.

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