JP2011146651A - Group iii nitride light emitting diode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce shape defects such as crack and chipping of a side surface of a group III nitride light emitting diode having a light emitting layer etc., provided on a nonpolar principal surface of a support base made of hexagonal group III nitride. <P>SOLUTION: The light emitting diode 11 has a light emitting structure 13 including the support base 17 made of a hexagonal group III nitride semiconductor and a semiconductor region 19. The semiconductor region 19 includes a first semiconductor layer 21, a second semiconductor layer 23, and the light emitting layer 25. A c-axis of the hexagonal group III nitride semiconductor of the support base 17 is tilted in an m-axis direction at a finite angle ALPHA with respect to a normal axis. The light emitting structure 13 has a pair of torn surfaces 27 and 29 crossing an m-n plane defined by the m-axis of the hexagonal group III nitride semiconductor and the normal axis, and a pair of cleavage surfaces 13a and 13b formed of the m-n plane or ä11-20} plane. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a group III nitride light emitting diode.

  Non-Patent Document 1 describes a semiconductor laser fabricated on a (11-22) plane GaN substrate. In this semiconductor laser, the resonance end face is formed by dry etching.

  Non-Patent Document 2 describes a light emitting diode fabricated on a (11-22) plane GaN substrate. This light emitting diode is chipped by dicing.

  Non-Patent Document 3 describes a light emitting diode fabricated on a (11-22) plane sapphire substrate. This light emitting diode is also chipped by dicing.

Hirokuni Asamizu et al., “Demonstration of 426 nm InGaN / GaN Laser Diodes Fabricated onFree-Standing Semipolar (11-22) Gallium Nitride Substrates”, AppliedPhysics Express, Vol.1, 091102 (2008) Natalie FELLOWS et al., “IncreasedPolarization Ratio on Semipolar (11-22) InGaN / GaN Light-Emitting Diodes with Increasing Indium Composition”, Japanese Journal of Applied Physics, Vol. 47, No. 10, 2008, pp.7854-7856 Hisashi Masui et al., “Light-polarization characteristics of electroluminescence from InGaN / GaN light-emitting diodesprepared on (11-22) -plane GaN”, Journal of Applied Physics, American Institute ofPhysics, 100, 113109 (2006)

  For example, a technique for producing a light emitting diode by growing a light emitting layer on a nonpolar main surface of a hexagonal group III nitride substrate such as GaN has been studied. Conventionally, when manufacturing such a light emitting diode, a light emitting layer or the like is grown on a group III nitride substrate, and then the substrate product is diced to perform dicing. However, dicing into chips may cause a shape defect such as chipping or chipping on the side surface of the chip. Such a shape defect affects the light emission distribution inside the light emitting diode, and also reduces the reliability of the light emitting diode. For this reason, there exists a problem that it leads to the fall of the yield at the time of manufacturing a light emitting diode.

  The present invention has been made in view of such problems, and a group III nitride light-emitting diode having a light emitting layer or the like provided on a nonpolar main surface of a support base made of hexagonal group III nitride The purpose is to reduce shape defects such as chipping and chipping on the side surfaces.

  In order to solve the above-described problems, a group III nitride light-emitting diode according to the present invention includes (a) a support base made of a hexagonal group III nitride semiconductor and having a semipolar main surface, and a semipolar main surface of the support base A light emitting structure including a semiconductor region provided thereon; and (b) an electrode provided on the semiconductor region. The semiconductor region includes a first semiconductor layer made of a group III nitride semiconductor of a first conductivity type, a second semiconductor layer made of a group III nitride semiconductor of a second conductivity type, and a first semiconductor made of a group III nitride semiconductor. A light emitting layer provided between the layer and the second semiconductor layer. The first semiconductor layer, the second semiconductor layer, and the light emitting layer are arranged along the normal axis of the semipolar main surface. The c-axis of the hexagonal group III nitride semiconductor of the support base is inclined at a finite angle ALPHA with respect to the normal axis in the direction of the m axis of the hexagonal group III nitride semiconductor. The light emitting structure includes a pair of a split section intersecting an mn plane defined by an m axis and a normal axis of a hexagonal group III nitride semiconductor, and a pair of an mn plane or a {11-20} plane. And a cleavage plane.

  In this group III nitride light-emitting diode, a pair of side surfaces is constituted by a split section, and the other pair of side surfaces is constituted by a cleavage plane. The fractured surface is a surface that intersects the mn plane of the hexagonal group III nitride semiconductor in the light emitting structure, and is a surface formed by cleavage. Further, the cleavage plane is an mn plane or a {11-20} plane. These cleavage planes and cleavage planes have sufficient flatness and perpendicularity as the side surfaces of the light emitting diode. Therefore, according to this group III nitride light-emitting diode, shape defects such as chipping and chipping on the side surface of the light-emitting diode can be reduced.

  In the group III nitride light-emitting diode, the angle formed between the normal axis and the c-axis of the hexagonal group III nitride semiconductor is preferably in the range of 45 degrees to 80 degrees or 100 degrees to 135 degrees. . In this case, in the group III nitride light-emitting diode, the angle formed between the normal axis and the c-axis of the hexagonal group III nitride semiconductor may be in the range of 63 degrees to 80 degrees or 100 degrees to 117 degrees. Further preferred.

  In the group III nitride light-emitting diode, the semipolar main surface is any of {20-21} plane, {10-11} plane, {20-2-1} plane, and {10-1-1} plane. It may be a slightly inclined surface that is off within a range of −5 degrees or more and +5 degrees or less from the above surface. Alternatively, in the group III nitride light-emitting diode, the semipolar main surface is a {20-21} plane, {10-11} plane, {20-2-1} plane, or {10-1-1} plane. May be.

Further, in the group III nitride light-emitting diode, it is preferable that the stacking fault density of the support base is 1 × 10 ⁴ cm ⁻¹ or less.

  In the group III nitride light-emitting diode, the support base is preferably made of GaN, AlGaN, AlN, InGaN, or InAlGaN.

  In the group III nitride light-emitting diode, the light-emitting layer may include a light-emitting region provided so as to generate light having a wavelength of 360 nm to 600 nm. Alternatively, the group III nitride light emitting diode may include a quantum well structure in which the light emitting layer is provided so as to generate light having a wavelength of 430 nm or more and 550 nm or less.

  Further, in the group III nitride light-emitting diode, the end face of the support base and the end face of the semiconductor region appear in each of the pair of split cross sections, and the reference surfaces orthogonal to the end faces of the support base and the semiconductor region and the m-axis of the support base The angle at which the end surface tilt angle, which is the angle formed with the surface, is projected on the first plane defined by the c-axis and m-axis of the hexagonal group III nitride semiconductor is (ALPHA-5) degrees or more and (ALPHA + 5) degrees or less. It is good also as a feature. In this case, in the group III nitride light-emitting diode, it is preferable that an angle obtained by projecting the end surface inclination angle on a second plane orthogonal to both the first plane and the normal axis is −5 degrees or more and +5 degrees or less.

  In the group III nitride light-emitting diode, the angle formed between the mn plane and the {11-20} plane is preferably −5 degrees or more and +5 degrees or less.

  According to the present invention, in a group III nitride light-emitting diode having a light emitting layer or the like provided on a nonpolar main surface of a support base made of hexagonal group III nitride, shape defects such as chipping and chipping on the side surface are reduced. it can.

FIG. 1 is a perspective view showing the structure of a group III nitride light-emitting diode according to this embodiment. FIG. 2 is a drawing showing a group III nitride semiconductor laser device. FIG. 3 is a drawing schematically showing a cross section defined by the c-axis and the m-axis. FIG. 4 is a drawing showing the main steps of a method for fabricating a group III nitride light emitting diode. FIG. 5A to FIG. 5C are diagrams showing main steps of a method for producing a group III nitride light-emitting diode.

  Hereinafter, embodiments of a group III nitride light-emitting diode according to the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a perspective view showing a structure of a group III nitride light emitting diode (hereinafter referred to as a light emitting diode) according to the present embodiment. The light emitting diode 11 includes a light emitting structure 13 and an electrode 15. The light emitting structure 13 includes a support base 17 and a semiconductor region 19. The support base 17 is made of a hexagonal group III nitride semiconductor and has a semipolar main surface 17a and a back surface 17b. The semiconductor region 19 is provided on the semipolar main surface 17 a of the support base 17. The electrode 15 is provided on the semiconductor region 19 of the light emitting structure 13. The semiconductor region 19 includes a first semiconductor layer 21, a second semiconductor layer 23, and a light emitting layer 25.

  The first semiconductor layer 21 is made of a first conductivity type group III nitride semiconductor, and contains at least one element of Ga, Al, and In and N in the composition. The first semiconductor layer 21 is made of, for example, n-type GaN, n-type InGaN, n-type AlGaN, n-type InAlGaN, or the like. The second semiconductor layer 23 is made of a Group III nitride semiconductor of the second conductivity type, and contains at least one element of Ga, Al, and In and N in the composition. The second semiconductor layer 23 is made of, for example, p-type GaN, p-type InGaN, p-type AlGaN, p-type InAlGaN, or the like. The second semiconductor layer 23 functions as an electronic block layer.

  The light emitting layer 25 is provided between the first semiconductor layer 21 and the second semiconductor layer 23. The light emitting layer 25 is made of a group III nitride semiconductor, and has well layers 25a and barrier layers 25b arranged alternately. The well layer 25a is made of, for example, InGaN, and the barrier layer 25b is made of, for example, GaN, InGaN, or the like. The well layer 25a can be a light emitting region provided to generate light having a wavelength of 360 nm to 600 nm. The light emitting layer 25 may include a quantum well structure provided to generate light having a wavelength of 430 nm or more and 550 nm or less. In other words, the light emitting layer 25 is suitable for generating light having a wavelength of 430 nm or more and 550 nm or less by utilizing the semipolar surface of the support base 17.

  The first semiconductor layer 21, the second semiconductor layer 23, and the light emitting layer 25 are arranged along the normal axis NX of the semipolar principal surface 17a. The light emitting structure 13 includes a pair of split sections 27 and 29 intersecting the mn plane defined by the m-axis and the normal axis NX of the hexagonal group III nitride semiconductor. The light emitting structure 13 includes cleavage planes 13a and 13b which are mn planes or {11-20} planes (that is, planes orthogonal to the a-axis) of hexagonal group III nitride semiconductors. The angle formed between this nm plane and the {11-20} plane (that is, the a plane) is preferably -5 degrees or more and +5 degrees or less.

  Referring to FIG. 1, an orthogonal coordinate system S and a crystal coordinate system CR are depicted. The normal axis NX is directed in the direction of the Z axis of the orthogonal coordinate system S. The semipolar principal surface 17a extends in parallel to a predetermined plane defined by the X axis and the Y axis of the orthogonal coordinate system S. FIG. 1 also shows a representative c-plane Sc. The c-axis of the hexagonal group III nitride semiconductor of the support base 17 is inclined at a finite angle ALPHA with respect to the normal axis NX in the m-axis direction of the hexagonal group III nitride semiconductor.

  The electrode 15 is in contact with the surface 19a of the semiconductor region 19 (for example, the second conductivity type contact layer 33). Another electrode 41 is provided on the back surface 17b of the support base 17, and the electrode 41 covers, for example, the back surface 17b of the support base 17.

  In the light emitting diode 11, the pair of fractured surfaces 27 and 29 intersect the mn plane defined by the m-axis and the normal axis NX of the hexagonal group III nitride semiconductor. The fractured surface 27 constitutes one side surface in the support base 17 and the semiconductor region 19, and the fractured surface 29 constitutes a side surface opposite to the fractured surface 27 in the support base 17 and the semiconductor region 19. The split surfaces 27 and 29 have flatness and perpendicularity superior to the side surface formed by dicing. The light emitting structure 13 includes a pair of cleaved surfaces 13a and 13b. The cleavage surface 13 a constitutes another side surface in the support base 17 and the semiconductor region 19, and the cleavage surface 13 b constitutes a side surface opposite to the cleavage surface 13 a in the support base 17 and the semiconductor region 19. The split sections 27 and 29 extend from the edge of the cleavage plane 13a to the edge of the cleavage plane 13b. The cleavage planes 13a and 13b are cleavage planes such as a-plane, for example, and the split sections 27 and 29 are different planes from the cleavage plane such as c-plane, m-plane or a-plane.

Here, FIG. 2 is a view showing the light emitting diode 11. FIG. 3 is a drawing schematically showing a cross section defined by the c-axis and the m-axis. In the light emitting diode 11, the end face 17 c of the support base 17 and the end face 19 c of the semiconductor region 19 appear in each of the split surfaces 27 and 29. Now, an angle (end surface inclination angle) BETA formed by the normal vector NA of the end faces 17c and 19c and the m-axis vector MA of the support base 17 is defined by the c-axis and m-axis of the group III nitride semiconductor. The angle component projected onto the plane S1 is assumed to be BETA1. Further, an angle component obtained by projecting the end surface inclination angle BETA on the second plane S2 orthogonal to both the first plane S1 and the normal axis NX is defined as BETA2. Here, BETA ² = (BETA ¹ ) ² + (BETA ² ) ² .

The angle component BETA1 is preferably in the range of (ALPHA-5) degrees to (ALPHA + 5) degrees. This angle range is shown in FIG. 3 as an angle formed by a representative m-plane _SM and the reference plane F _A. A representative m-plane _SM is depicted from the inside to the outside of the light emitting structure in FIG. 3 for ease of understanding. Reference plane _{F A} extends along the end surface 19c of the end surface 17c and the semiconductor region 19 of the support base 17. The light emitting diode 11 has an end face that satisfies a sufficient verticality with respect to an end face inclination angle BETA taken from one of the c-axis and the m-axis to the other.

  Moreover, it is preferable that the angle component BETA2 is in a range of not less than −5 degrees and not more than +5 degrees in the second plane S2. Thereby, the end surfaces 27 and 29 of the light emitting diode 11 have sufficient perpendicularity with respect to an angle defined in a plane perpendicular to the normal axis NX of the semipolar surface 17a.

  Referring again to FIG. 1, in the light emitting diode 11, the thickness DSUB of the support base 17 is preferably 400 μm or less in order to obtain high-quality split sections 27 and 29. Further, in order to obtain a higher-quality split section, the thickness DSUB is more preferably 50 μm or more and 250 μm or less. This also facilitates handling and can improve production yield.

  The angle ALPHA formed by the normal axis NX and the c-axis of the hexagonal group III nitride semiconductor is preferably 45 degrees or more, and preferably 80 degrees or less. Alternatively, the angle ALPHA is preferably 100 degrees or more, and preferably 135 degrees or less. If the angle is less than 45 degrees or more than 135 degrees, there is a high possibility that the end face formed by pressing is an m-plane. As a result, the pair of split sections 27 and 29 have an untargeted shape, and the symmetry of the emission intensity distribution may be reduced. Further, when the angle is more than 80 degrees and less than 100 degrees, the desired flatness and perpendicularity may not be obtained.

  More preferably, the angle ALPHA formed by the normal axis NX and the c-axis of the hexagonal group III nitride semiconductor is preferably 63 degrees or more, and more preferably 80 degrees or less. Alternatively, the angle ALPHA is preferably 100 degrees or more, and preferably 117 degrees or less. If the angle is less than 63 degrees or more than 117 degrees, the m-plane may appear in a part of the end face formed by pressing. Further, when the angle is more than 80 degrees and less than 100 degrees, the desired flatness and perpendicularity may not be obtained.

  The semipolar principal surface 17a can be a {20-21} plane, a {10-11} plane, a {20-2-1} plane, or a {10-1-1} plane. Furthermore, a surface slightly inclined from these surfaces within a range of −5 degrees or more and +5 degrees or less is also suitable as the main surface. In these typical semipolar surfaces 17a, it is possible to provide split sections 27 and 29 having sufficient flatness and perpendicularity as side surfaces of the light emitting diode 11.

The stacking fault density of the support substrate 17 can be 1 × 10 ⁴ cm ⁻¹ or less. Since the stacking fault density is 1 × 10 ⁴ cm ⁻¹ or less, it is unlikely that the flatness and / or perpendicularity of the fractured surfaces 27 and 29 will be disturbed due to accidental circumstances. The support base 17 can be made of GaN, AlN, AlGaN, InGaN, or InAlGaN. When a support base made of these gallium nitride based semiconductors is used, good fracture sections 27 and 29 can be obtained. In particular, when the support base 17 made of InGaN is used, the lattice mismatch rate between the support base 17 and the light emitting layer 25 can be reduced, and the crystal quality can be improved.

  FIG. 4 is a drawing showing main steps of a method for producing the light emitting diode 11 according to the present embodiment. Referring to FIG. 5 (a), a substrate 51 is shown. In step S101, a substrate 51 for manufacturing a light emitting diode is prepared. The c-axis (vector VC) of the hexagonal group III nitride semiconductor of the substrate 51 is inclined at a finite angle ALPHA with respect to the normal axis NX in the m-axis direction (vector VM) of the hexagonal group III nitride semiconductor. ing. Therefore, the substrate 51 has a semipolar main surface 51a made of a hexagonal group III nitride semiconductor.

  In step S102, a substrate product SP is formed. In FIG. 5A, the substrate product SP is depicted as a substantially disk-shaped member, but the shape of the substrate product SP is not limited to this. In order to obtain the substrate product SP, first, in step S103, the light emitting structure 55 is formed. The light emitting structure 55 includes the semiconductor region 53 and the substrate 51. In step S103, the semiconductor region 53 is formed on the semipolar main surface 51a. In order to form the semiconductor region 53, the first semiconductor layer 57 made of a gallium nitride semiconductor of the first conductivity type, the light emitting layer 59, and the gallium nitride semiconductor of the second conductivity type are formed on the semipolar main surface 51a. The second semiconductor layer 61 is grown in order. The first semiconductor layer 57 can include, for example, an n-type buffer layer, and the second semiconductor layer 61 can include, for example, an electron block layer. The light emitting layer 59 is provided between the first semiconductor layer 57 and the second semiconductor layer 61. The first semiconductor layer 57, the light emitting layer 59, and the second semiconductor layer 61 are arranged along the normal axis NX of the semipolar main surface 51a. These semiconductor layers are epitaxially grown. The surface of the semiconductor region 53 is covered with an insulating film 54. The insulating film 54 is made of, for example, silicon oxide. The insulating film 54 has an opening 54a.

  In step S <b> 104, the anode electrode 58 a and the cathode electrode 58 b are formed on the light emitting structure 55. In addition, before forming the electrode on the back surface of the substrate 51, the back surface of the substrate used for crystal growth is polished to form a substrate product SP having a desired thickness DSUB. In the formation of the electrodes, for example, the anode electrode 58a is formed on the semiconductor region 53, and the cathode electrode 58b is formed on the back surface (polishing surface) 51b of the substrate 51. The anode electrode 58a is provided on a part of the semiconductor region 53, and the cathode electrode 58b covers the entire surface of the back surface 51b. Through these steps, the substrate product SP is formed. The substrate product SP includes a first surface 63a and a second surface 63b located on the opposite side.

  In step S105, as shown in FIG. 5B, the first surface 63a of the substrate product SP is scribed. This scribing is performed using a laser scriber 10a. A scribe groove 65a is formed by scribing. In FIG. 5B, a total of 10 scribe grooves, 5 in length and 5 in width, have already been formed, and the formation of the scribe grooves 65b is being advanced using the laser beam LB. The length of the scribe groove 65a along one direction is approximately equal to the length of the intersection line between the a-n plane and the first plane 63a defined by the a-axis and the normal axis NX of the hexagonal group III nitride semiconductor. Equally, the laser beam LB is irradiated over the entire range of the intersecting line. Further, the length of the scribe groove 65a along the direction orthogonal to this is the mn plane defined by the m-axis and the normal axis NX of the hexagonal group III nitride semiconductor, or the hexagonal group III nitride. The length of the intersection line between the {11-20} surface of the semiconductor and the first surface 63a is substantially equal, and the entire range of the intersection line is irradiated with the laser beam LB. By irradiation with the laser beam LB, a groove extending in the X direction and the Y direction orthogonal to each other and reaching the semiconductor region is formed in the first surface 63a.

  In step S106, as shown in FIG. 5C, the substrate product SP is separated by pressing the substrate product SP against the second surface 63b to form the substrate product SP1 and the chip LC. The pressing is performed using a breaking device such as a blade 69. The blade 69 includes an edge 69a extending in one direction and at least two blade surfaces 69b and 69c defining the edge 69a. The substrate product SP1 is pressed on the support device 71. The support device 71 includes a support surface 71a and a groove 71b, and the groove 71b extends in one direction. The groove 71b is formed in the support surface 71a. The substrate product SP1 is positioned on the groove 71b on the support device 71 by aligning the direction and position of the scribe groove 65a of the substrate product SP1 with the extending direction of the groove 71b of the support device 71. The edge of the breaking device is aligned with the extending direction of the groove 71b, and the edge of the breaking device is pressed against the substrate product SP1 from the direction intersecting the second surface 63b. The intersecting direction is preferably substantially perpendicular to the second surface 63b. Thereby, the substrate product SP is separated to form the substrate product SP1 and the chip LC. By pressing, a chip LC having end faces 67a and 67b which are a pair of split sections and end faces 68a and 68b which are a pair of cleavage faces is formed, and these end faces 67a, 67b, 68a and 68b It has sufficient verticality and flatness as side surfaces.

  The formed chip LC has a pair of end surfaces 67a and 67b and a pair of end surfaces 68a and 68b formed by the above separation, and each of the end surfaces 67a, 67b, 68a and 68b is formed from the first surface 63a. It extends to the second surface 63b. Therefore, the end surfaces 67a, 67b, 68a, and 68b constitute the side surfaces of the light emitting diode, and the end surfaces 67a, 67b intersect the XZ plane. This XZ plane corresponds to the mn plane defined by the m-axis and the normal axis NX of the hexagonal group III nitride semiconductor.

  According to this method, after scribing the first surface 63a of the substrate product SP in the direction of the a-axis of the hexagonal group III nitride semiconductor, the substrate product SP is pressed against the second surface 63b. The product SP is separated to form a new substrate product SP1 and a chip LC. Therefore, end surfaces 67a and 67b as side surfaces of the chip LC are formed so as to intersect the mn plane. According to this side surface formation, the pair of end surfaces 67a and 67b are provided with sufficient flatness and verticality as the side surface of the light emitting diode.

  Through the above-described steps, individual light-emitting diode chips each including a split cross section intersecting with the mn plane and a cleavage plane composed of the mn plane or {11-20} plane are completed.

  In the manufacturing method according to the present embodiment, the angle ALPHA can be in the range of 45 degrees to 80 degrees or 100 degrees to 135 degrees. If the angle is less than 45 degrees or more than 135 degrees, there is a high possibility that the end face formed by pressing is an m-plane. As a result, the end faces 67a and 67b have an untargeted shape, and the symmetry of the emission intensity distribution may be reduced. Further, when the angle is more than 80 degrees and less than 100 degrees, the desired flatness and perpendicularity may not be obtained. More preferably, the angle ALPHA can be in the range of 63 degrees to 80 degrees or 100 degrees to 117 degrees. If the angle is less than 45 degrees or more than 135 degrees, the m-plane may appear in a part of the end face formed by pressing. Further, when the angle is more than 80 degrees and less than 100 degrees, the desired flatness and perpendicularity may not be obtained. The semipolar principal surface 51a can be a {20-21} plane, a {10-11} plane, a {20-2-1} plane, or a {10-1-1} plane. Furthermore, a surface slightly inclined from these surfaces within a range of −5 degrees or more and +5 degrees or less is also suitable as the main surface. In these typical semipolar planes, the sides of the light emitting diode can be provided with sufficient flatness and verticality.

  The substrate 51 can be made of GaN, AlN, AlGaN, InGaN, or InAlGaN. When a substrate made of these gallium nitride semiconductors is used, a side surface suitable as a light emitting diode can be obtained. The substrate 51 is preferably made of GaN.

  In step S104 for forming the substrate product SP, the semiconductor substrate used for crystal growth was subjected to processing such as slicing or grinding so that the substrate thickness was 400 μm or less, and the second surface 63b was formed by polishing. It can be a machined surface. With this substrate thickness, the end faces 67a and 67b having sufficient flatness and perpendicularity and free from ion damage can be formed with high yield. More preferably, the second surface 63b is a polished surface formed by polishing, and the substrate is polished to a thickness of 250 μm or less. In order to handle the substrate product SP relatively easily, the substrate thickness is preferably 50 μm or more.

  In the manufacturing method according to the present embodiment, the end surface inclination angle BETA described with reference to FIG. 2 is also defined for the bar LB1. In the bar LB1, the angle component BETA1 of the end surface inclination angle BETA is in a first plane (a plane corresponding to the first plane S1 in the description with reference to FIG. 2) defined by the c-axis and the m-axis of the group III nitride semiconductor. It is preferably in the range of (ALPHA-5) degrees to (ALPHA + 5) degrees. The end faces 67a and 67b of the bar LB1 satisfy sufficient perpendicularity with respect to the angle component of the end face inclination angle BETA taken from one of the c-axis and the m-axis to the other. Further, the angle component BETA2 of the end surface inclination angle BETA is preferably in the range of −5 degrees to +5 degrees on the second plane (the plane corresponding to the second plane S2 shown in FIG. 2). At this time, the end surfaces 67a and 67b of the bar LB1 satisfy a sufficient perpendicularity with respect to the angle component of the end surface inclination angle BETA defined by a plane perpendicular to the normal axis NX of the semipolar surface 51a.

  The end faces 67a and 67b are formed by a break by pressing against a plurality of gallium nitride based semiconductor layers epitaxially grown on the semipolar surface 51a. Because of the epitaxial film on the semipolar surface 51a, the end surfaces 67a and 67b are not cleaved surfaces with a low surface index such as c-plane, m-plane, or a-plane. However, in the break of the lamination of the epitaxial film on the semipolar surface 51a, the end surfaces 67a and 67b have sufficient flatness and perpendicularity as the side surfaces of the light emitting diode.

  According to the light emitting diode 11 and the manufacturing method thereof described above, the following effects can be obtained. As described above, the conventional chip formation by dicing may cause a shape defect such as chipping or chipping on the side surface of the chip. Such a shape defect affects the light emission distribution inside the light emitting diode, and also reduces the reliability of the light emitting diode. For this reason, there exists a problem that it leads to the fall of the yield at the time of manufacturing a light emitting diode. On the other hand, in the light emitting diode 11 and the manufacturing method thereof according to the present embodiment, the pair of side surfaces are constituted by the split sections 27 and 29 (end surfaces 67a and 67b), and the other pair of side surfaces are the cleavage surfaces 13a and 13b. It is composed by. The split sections 27 and 29 (end faces 67a and 67b) are planes intersecting the mn plane of the hexagonal group III nitride semiconductor in the light emitting structure 13 and formed by cleaving. Further, the cleavage planes 13a and 13b are mn planes or {11-20} planes. As described above, the split sections 27 and 29 (end faces 67a and 67b) and the cleaved faces 13a and 13b have sufficient flatness and perpendicularity as the side surfaces of the light emitting diode. Therefore, according to the light emitting diode 11 and the manufacturing method thereof according to the present embodiment, shape defects such as chipping and chipping on the side surface of the light emitting diode 11 can be reduced.

(Example)
As described below, a light emitting diode was grown on a semipolar plane GaN substrate (corresponding to the support base 17 in the above embodiment) by metal organic vapor phase epitaxy. As the substrate, a {20-21} plane GaN substrate cut out at an angle of 75 degrees in the m-axis direction from a (0001) GaN ingot grown thick by the HVPE method was used. Note that trimethylgallium (TMGa), trimethylaluminum (TMAl), trimethylindium (TMIn), ammonia (NH ₃ ), and silane (SiH ₄ ) were used as raw materials.

First, the temperature of the GaN substrate was raised to 1050 ° C. in an NH ₃ and H ₂ atmosphere and held for 10 minutes to perform pretreatment (thermal cleaning). Thereafter, the substrate temperature was set to 1100 ° C., and an n-type GaN layer (corresponding to the first semiconductor layer 21) was grown to 2 μm on the GaN substrate.

Subsequently, after the substrate temperature was lowered to 840 ° C. and an n-type In _0.02 Ga _0.98 N buffer layer was grown, a quantum well light emitting layer (corresponding to the light emitting layer 25) was grown. At this time, the growth temperature of the well layer was 740 ° C., and the growth temperature of the barrier layer was 840 ° C. Thereafter, the substrate temperature is raised to 1000 ° C., a p-type Al _0.18 Ga _0.82 N electron blocking layer (corresponding to the second semiconductor layer 23) is grown by 20 nm, and a p-type GaN contact layer ( (Corresponding to the contact layer 33) was grown by 50 nm.

  Subsequently, an electrode made of Ni / Au (corresponding to the anode electrode 15) was deposited on the contact layer 33, and a pad electrode made of Ti / Au was deposited separately. Further, an electrode made of Ti / Al (corresponding to the cathode electrode 41) was deposited on the back surface of the GaN substrate. Thereafter, a scribe line is put on the entire surface of the substrate product on which the n-type GaN layer, the quantum well light emitting layer, the p-type AlGaN electron blocking layer, and the like are formed with a laser scriber, that is, the back surface of the substrate product (that is, A breaking blade was pressed against the back surface of the GaN substrate to form a chip.

  As a result of observing the fractured surface formed by the break with a scanning electron microscope, no remarkable unevenness was observed. From this, the flatness (size of irregularities) of the fractured surface is estimated to be 20 nm or less. Further, the perpendicularity of the cut surface to the sample surface was within a range of ± 5 degrees.

  As a result, a light emitting diode was obtained in which the four side surfaces of the chip had sufficient perpendicularity to the main surface of the substrate without causing defects such as cracks and chips at the chip end. As a result, a light emitting diode having a good symmetry of the emission intensity distribution was realized.

DESCRIPTION OF SYMBOLS 11 ... Light emitting diode, 13 ... Light emitting structure, 13a, 13b ... Cleaved surface, 15 ... Anode electrode, 17 ... Support base | substrate, 17a ... Semipolar main surface, 17b ... Back surface, 17c ... End surface, 19 ... Semiconductor region, 19c ... End face, 21 ... first semiconductor layer, 23 ... second semiconductor layer, 25 ... light emitting layer, 25a ... well layer, 25b ... barrier layer, 27, 29 ... split section (end face), 33 ... contact layer, 41 ... cathode electrode , BETA ... end face inclination angle, BREAK ... breaking line, F _A ... reference plane, LB ... laser beam, LB1 ... bar, NA ... normal vector, NX ... normal axis, Sc ... c plane, S _M ... m plane.

Claims (12)

A light emitting structure including a support base made of a hexagonal group III nitride semiconductor and having a semipolar main surface; and a semiconductor region provided on the semipolar main surface of the support base;
An electrode provided on the semiconductor region,
The semiconductor region includes a first semiconductor layer made of a group III nitride semiconductor of a first conductivity type, a second semiconductor layer made of a group III nitride semiconductor of a second conductivity type, and the group III nitride semiconductor. A light emitting layer provided between one semiconductor layer and the second semiconductor layer;
The first semiconductor layer, the second semiconductor layer, and the light emitting layer are arranged along a normal axis of the semipolar main surface,
The c-axis of the hexagonal group III nitride semiconductor of the support base is inclined at a finite angle ALPHA with respect to the normal axis in the m-axis direction of the hexagonal group III nitride semiconductor,
The light emitting structure includes a pair of split sections intersecting an mn plane defined by an m axis and a normal axis of the hexagonal group III nitride semiconductor, the mn plane, or {11-20} A group III nitride light-emitting diode comprising a pair of cleavage planes.   The angle formed by the normal axis and the c-axis of the hexagonal group III nitride semiconductor is in the range of 45 degrees to 80 degrees or 100 degrees to 135 degrees. Group III nitride light-emitting diodes.   The angle formed between the normal axis and the c-axis of the hexagonal group III nitride semiconductor is in the range of 63 degrees to 80 degrees, or 100 degrees to 117 degrees. A group III nitride light-emitting diode as described in 1.   The semipolar principal surface is −5 degrees or more +5 from any one of {20-21}, {10-11}, {20-2-1}, and {10-1-1} surfaces. The group III nitride light-emitting diode according to any one of claims 1 to 3, wherein the III-nitride light-emitting diode is a slightly inclined surface that is turned off within a range of not more than 50 degrees.   The semi-polar main surface is a {20-21} plane, a {10-11} plane, a {20-2-1} plane, or a {10-1-1} plane. The group-III nitride light emitting diode as described in any one of -3. The group III nitride light-emitting diode according to claim 1, wherein a stacking fault density of the support base is 1 × 10 ⁴ cm ⁻¹ or less.   The group III nitride light-emitting diode according to claim 1, wherein the support base is made of GaN, AlGaN, AlN, InGaN, or InAlGaN.   The group III nitride light-emitting diode according to any one of claims 1 to 7, wherein the light-emitting layer includes a light-emitting region provided to generate light having a wavelength of 360 nm to 600 nm.   The group III nitride light-emitting diode according to any one of claims 1 to 7, wherein the light-emitting layer includes a quantum well structure provided to generate light having a wavelength of 430 nm or more and 550 nm or less. . In each of the pair of split sections, an end surface of the support base and an end surface of the semiconductor region appear,
An end surface inclination angle that is an angle formed between each end surface of the support base and the semiconductor region and a reference plane orthogonal to the m-axis of the support base is defined by the c-axis and m-axis of the hexagonal group III nitride semiconductor. The group III nitride light-emitting diode according to any one of claims 1 to 9, wherein an angle projected on the first plane is not less than (ALPHA-5) degrees and not more than (ALPHA + 5) degrees.   11. The group III according to claim 10, wherein an angle obtained by projecting the end surface inclination angle onto a second plane orthogonal to both the first plane and the normal axis is −5 degrees or more and +5 degrees or less. Nitride light emitting diode.   The group III nitride light emission according to any one of claims 1 to 11, wherein an angle formed between the mn plane and the {11-20} plane is -5 degrees or more and +5 degrees or less. diode.

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