JP2010206133A - Light emitting element, method of manufacturing the same, and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for enhancing the light extraction efficiency without narrowing the interconnection width of an electrode on the light extraction side. <P>SOLUTION: A light emitting element 1 includes: an active layer 10; a pair of clad layers 9 and 11 that hold the active layer 10 in between; an n-type contact layer 12 formed in a form of dots on the n-type clad layer 11 on the light extraction side out of the pair of clad layers 9 and 11; and an n-type electrode 14 electrically connected to the n-type contact layer 12. The n-type electrode 14 has an electrode interconnection part 17 and an electrode relay part 18 which constitute a bridge structure. The electrode interconnection part 17 is separated from the n-type contact layer 12 in a thickness direction Z of the light emitting element and is so formed as to overlap the n-type contact layer 12 in a planar view. The electrode relay part 18 electrically connect the n-type contact layer 12 and the electrode interconnection part 17 at the sites where the n-type contact layer 12 is formed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a light emitting element, a manufacturing method thereof, and an electronic apparatus.

  In an AlGaInP-based red LED device, there are the following three structures as typical structures for obtaining high efficiency. One is a DBR-LED (DISTRIBUTED BRAGG REFLECTOR EHNHANCED ABSOBING SUBSTRATE LEDs) using Bragg reflection. The other is TS-LED (TRANSPARENT SUBSTRATE LEDs) using a transparent substrate. The other is ODR-LED (OMNIDIRECTIONAL REFLECTOR for LEDs) using a reflector. Among these, the ODR-LED is a red LED device structure that is expected from now on because it has higher luminance and is less expensive than the TS-LED (see, for example, Patent Document 1).

  In the structure of the ODR-LED, the upper electrode on the light extraction side is an n-type electrode, and the lower electrode on the opposite side is a p-type electrode. The p-type electrode is formed in a dot shape. The area occupied by the p-type electrode is often designed to be about 1% of the LED chip area. On the other hand, the shape of the n-type electrode is, for example, “concentric” shown in FIG. 25A, “saddle” shown in FIG. 25B, and “Yagi” shown in FIG. There are various types such as “antenna type”.

  When the total wiring area of the n-type electrode is several percent (1 to 10%) or less with respect to the chip area, the chip area is relatively large with respect to the wiring area of the n-type electrode. For this reason, the wiring of the n-type electrode does not affect the light extraction efficiency so much. On the other hand, when the chip area is relatively small, the proportion of the area occupied by the wiring portion of the n-type electrode including the pad portion for wire bonding in the light extraction surface increases. For this reason, the arrangement and size of wire bonding pads, the arrangement of radiative recombination points, the appropriate arrangement of n-type electrodes that grasps the light spread and current diffusion, wiring width, wiring length, electrode shape, etc. Very effective. Therefore, when downsizing the LED chip, the electrode arrangement considering the light extraction side electrode shape and light spread is very important. Therefore, conventionally, various ideas have been made regarding the electrode structure on the light extraction side (see, for example, Patent Documents 2 to 4).

FIG. 26 is a top view illustrating the structure of a conventional light emitting device (ODR-LED). 27 is a cross-sectional view taken along line A′-B ′ of FIG. 26, and FIG. 28 is a cross-sectional view taken along line C′-D ′ of FIG. 26. The illustrated light emitting element 51 is generally configured to include a support layer 52, a semiconductor layer 53, and a light extraction layer 54. The semiconductor layer 53 is stacked on the support layer 52, and the light extraction layer 54 is stacked on the semiconductor layer 53. The support layer 52 has a structure in which an ohmic metal layer 55, a support substrate 56, a reflective metal layer 57, and an insulating layer 58 are laminated in this order. The semiconductor layer 53 has a structure in which a p-type cladding layer 59, an active layer 60, an n-type cladding layer 61, and an n-type contact layer 62 are stacked in this order. The light extraction layer 54 has a structure having an overcoat layer 63 and an n-type electrode 64. A plurality of p-type electrodes 65 are formed in a dot shape on the insulating layer 58. On the surface (upper surface) of the n-type cladding layer 61, irregularities 66 called texture are formed. Further, an n-type contact layer 62 and an n-type electrode 64 are formed on the surface of the n-type cladding layer 61 in a portion excluding the formation portion of the irregularities 66.
Here, a GaAs (gallium arsenide) layer is formed as an n-type contact layer 62 at a portion corresponding to the wiring under the n-type electrode 64, and AuGe (gold germanium) -Ni (nickel) / Au is formed thereon as an electrode material. It has a structure in which it is vapor-deposited, alloyed, and ohmic joined. For this reason, the n-type contact layer 62 is made of GaAs, and the n-type electrode 64 is made of AuGe—Ni / Au. The n-type electrode 64 is formed in the aforementioned Yagi antenna type wiring shape. The p-type electrode 65 is disposed at a position where it does not overlap the n-type electrode 64 in plan view.

  When operating the light emitting element 51 having the above-described configuration, carriers (electrons) are transferred from the n-type electrode 64 and the p-type electrode 65 to the active layer 60 via the corresponding n-type cladding layer 61 and p-type cladding layer 59, respectively. , Holes). Thus, light is emitted by recombination of electron-hole pairs inside the active layer 60 forming a pn junction. Thus, the light emitted from the active layer 60 is extracted from the surface of the n-type cladding layer 61 (the surface on which the irregularities 66 are formed) to the outside of the semiconductor layer 53.

JP 2007-221029 A JP-A-5-145119 JP-A-6-5912 JP-A-6-5921

  By the way, in the conventional light emitting device 51, in order to increase the external quantum efficiency, the forward voltage applied between the n-type electrode 64 and the p-type electrode 65 is decreased, or reflection of light on the semiconductor surface is suppressed to reduce the external quantum efficiency. It is necessary to increase the amount of light extracted. In order to lower the forward voltage, it is effective to increase the number of p-type electrodes 65. However, as shown in FIG. 26, the distance Lp between the p-type electrodes 65 adjacent in a plane and the plane distance Lr between the n-type electrode 64 and the p-type electrode 65 closest to the n-type electrode 64 enter the light spreading region. If it becomes shorter, light absorption and light shielding by the electrode increase. For this reason, on the contrary, the luminous efficiency is lowered. For example, in order to arrange more p-type electrodes 65, when the distance Lp is made constant and the distance Lr is shortened, the carrier is regenerated in the active layer 60 immediately above the p-type electrode 65 as shown in FIG. Light emitted by the coupling is blocked by the n-type electrode 65 existing in the light spreading region. Further, in the n-type contact layer 62 made of GaAs, a part of the light incident thereon is absorbed. For this reason, the light absorbed by the n-type contact layer 62 cannot be extracted to the outside. As a result, the external quantum efficiency may be lowered in spite of increasing the number of p-type electrodes 65. In addition, reducing the wiring width of the n-type electrode 64 to reduce the occupation ratio of the n-type electrode 64 on the light extraction surface is an effective means for increasing the light output. However, at present, when the wiring width of the n-type electrode 64 is less than a certain dimension, it becomes difficult to lift off the metal layer constituting the n-type electrode 64 in manufacturing. Further, if the wiring width of the n-type electrode 64 is narrowed, the wiring resistance increases characteristically, leading to an increase in the forward voltage.

  A main object of the present invention is to provide a technique capable of increasing the light extraction efficiency without reducing the wiring width of the electrode on the light extraction side.

  The present invention provides an active layer, a pair of clad layers sandwiching the active layer, a contact layer formed in a dot shape on the clad layer on the light extraction side of the pair of clad layers, and the contact layer A light extraction side electrode that is electrically connected, and the light extraction side electrode is spaced apart from the contact layer in the thickness direction of the light emitting element and is formed to overlap the contact layer in a planar manner And a light emitting element formed in a bridge structure including an electrode relay portion that electrically connects the contact layer and the electrode wiring portion at a portion where the contact layer is formed.

  In the light emitting device according to the present invention, the contact layer is formed in a dot shape on the light extraction side cladding layer, and the electrode wiring portion of the light extraction side electrode is formed in a state of being separated from the contact layer. It is possible to extract light from below the electrode wiring portion to the outside of the cladding layer (semiconductor layer).

  According to the present invention, the light extraction efficiency can be increased without reducing the wiring width of the light extraction side electrode. For this reason, it becomes possible to improve the external quantum efficiency of a light emitting element.

It is a top view explaining an example of the basic structure of the light emitting element which concerns on this invention. It is AB sectional drawing of FIG. It is CD sectional drawing of FIG. It is a figure explaining operation | movement of a light emitting element. It is the figure which compared the arrangement | positioning relationship of an electrode. It is FIG. (1) explaining an example of the manufacturing method of the light emitting element which concerns on embodiment of this invention. It is FIG. (2) explaining an example of the manufacturing method of the light emitting element which concerns on embodiment of this invention. It is FIG. (3) explaining an example of the manufacturing method of the light emitting element which concerns on embodiment of this invention. It is FIG. (4) explaining an example of the manufacturing method of the light emitting element which concerns on embodiment of this invention. It is FIG. (5) explaining an example of the manufacturing method of the light emitting element which concerns on embodiment of this invention. It is FIG. (6) explaining an example of the manufacturing method of the light emitting element which concerns on embodiment of this invention. It is FIG. (7) explaining an example of the manufacturing method of the light emitting element which concerns on embodiment of this invention. It is FIG. (8) explaining an example of the manufacturing method of the light emitting element which concerns on embodiment of this invention. It is FIG. (9) explaining an example of the manufacturing method of the light emitting element which concerns on embodiment of this invention. It is FIG. (10) explaining an example of the manufacturing method of the light emitting element which concerns on embodiment of this invention. It is a figure (the 11) explaining an example of the manufacturing method of the light emitting element which concerns on embodiment of this invention. It is FIG. (12) explaining an example of the manufacturing method of the light emitting element which concerns on embodiment of this invention. It is FIG. (13) explaining an example of the manufacturing method of the light emitting element which concerns on embodiment of this invention. It is FIG. (14) explaining an example of the manufacturing method of the light emitting element which concerns on embodiment of this invention. It is FIG. (1) explaining the other example of the manufacturing method of the light emitting element which concerns on embodiment of this invention. It is FIG. (2) explaining the other example of the manufacturing method of the light emitting element which concerns on embodiment of this invention. It is FIG. (3) explaining the other example of the manufacturing method of the light emitting element which concerns on embodiment of this invention. It is FIG. (4) explaining the other example of the manufacturing method of the light emitting element which concerns on embodiment of this invention. It is FIG. (5) explaining the other example of the manufacturing method of the light emitting element which concerns on embodiment of this invention. It is a figure explaining an example of the wiring shape of an n-type electrode. It is a top view explaining the structure of the conventional light emitting element. It is A'-B 'sectional drawing of FIG. It is C'-D 'sectional drawing of FIG. It is a figure which shows the example of arrangement | positioning of the electrode in the conventional light emitting element.

  Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the technical scope of the present invention is not limited to the embodiments described below, and various modifications and improvements have been made within the scope of deriving specific effects obtained by the constituent requirements of the invention and combinations thereof. Including form.

Embodiments of the present invention will be described in the following order.
1. 1. Configuration of light emitting element 2. Operation of light emitting element 3. Manufacturing method of light emitting element Application examples

<1. Configuration of light emitting element>
1 to 3 are diagrams for explaining an example of a basic structure of a light-emitting element according to the present invention. FIG. 1 is a top view of the light-emitting element, FIG. FIG. 1 shows a cross-sectional view along the line CD in FIG.

  The illustrated light emitting device 1 is applied to an AlGaInP red light emitting diode having an ODR (OMNIDIRECTIONAL REFLECTOR) structure, for example. The light emitting element 1 is generally formed in a chip shape having a square shape (square, rectangle, etc.) in plan view. 1 to 3, the surface direction of the light emitting element 1 is defined as the X direction and the Y direction, and the thickness direction of the light emitting element 1 is defined as the Z direction. The X direction, the Y direction, and the Z direction are directions perpendicular to each other. The X direction is a direction parallel to one of the four sides defining the outer peripheral portion of the light emitting element 1, and the Y direction is a direction parallel to the other one side. The light-emitting element 1 is generally configured to include a support layer 2, a semiconductor layer 3, and a light extraction layer 4. The semiconductor layer 3 is stacked on the support layer 2, and the light extraction layer 4 is stacked on the semiconductor layer 3.

[Schematic structure of support layer]
The support layer 2 has a structure in which an ohmic metal layer 5, a support substrate 6, a reflective metal layer 7, and an insulating layer 8 are laminated in this order.

[Schematic structure of semiconductor layer]
The semiconductor layer 3 has a structure in which a p-type cladding layer 9, an active layer 10, an n-type cladding layer 11, and an n-type contact layer 12 are stacked in this order.

[Schematic configuration of light extraction layer]
The light extraction layer 4 has a structure having an overcoat layer 13 and an n-type electrode 14.

[Detailed structure of support layer]
The ohmic metal layer 5 is formed on the lower surface (back surface) of the support substrate 6. The ohmic metal layer 5 is formed of, for example, a metal layer in which an AuGe alloy layer, a nickel layer, and an Au layer are stacked in this order.

  The support substrate 6 is configured using, for example, a flat plate-shaped GaAs (gallium arsenide) substrate, GaP (gallium phosphorus) substrate, or the like. The support substrate 6 is a bonded substrate that is bonded during the manufacturing process of the light-emitting element 1 described later. The reflective metal layer 7 is formed on the upper surface (front surface) of the support substrate 6.

  The reflective metal layer 7 is formed using a metal having a high reflectance in the light emission wavelength region of the light emitting element 1 (red light emission region in the present embodiment), for example, a metal such as Au (gold) or Ag (silver). . The reflective metal layer 7 also serves as an electrode layer for injecting carriers serving as electric energy for light emission into the active layer 10.

  The insulating layer 8 is made of a film forming material that optically transmits light, such as SiO2 (silicon oxide). The thickness of the insulating layer 8 is set to be λ / (4n) where “λ” is the wavelength of light incident on the insulating layer 8 and “n” is the dielectric constant of the insulating layer 8. By setting the thickness of the insulating layer 8 in this way, light absorption in the insulating layer 8 is suppressed. For this reason, the utilization efficiency of light becomes high.

  A plurality of p-type electrodes 15 are embedded in the insulating layer 8. The p-type electrode 15 serves as a positive electrode for injecting carriers (holes) into the active layer 10 through the p-type cladding layer 9. The p-type electrode 15 is formed in a dot shape in the plane of the light emitting element 1 (in the XY plane). Each p-type electrode 15 is formed in a circular shape in plan view. However, the planar shape of the p-type electrode 15 is not limited to a circle, and may be a polygon such as a quadrangle. The p-type electrodes 15 are arranged in a state of being planarly dispersed in the insulating layer 8. The p-type electrode 15 is provided at a position where it does not overlap the n-type electrode 14 in plan view. The p-type electrode 15 is formed so as to penetrate the insulating layer 8. The lower end portion of the p-type electrode 15 is electrically connected to the reflective metal layer 7, and the upper end portion of the p-type electrode 15 is electrically connected to the p-type cladding layer 9.

[Detailed structure of semiconductor layer]
The semiconductor layer 3 is configured using an AlGaInP-based semiconductor. The AlGaInP-based semiconductor refers to a compound semiconductor containing 3B group element Al (aluminum), Ga (gallium) or In (indium) in the long-period periodic table and 5B group element P (phosphorus). The p-type cladding layer 9 is disposed so as to face the reflective metal layer 7 with the insulating layer 8 interposed therebetween. The p-type cladding layer 9 is provided between the insulating layer 8 and the active layer 10. The active layer 10 is sandwiched between a p-type cladding layer 9 and an n-type cladding layer 11 that form a pair on the upper and lower sides.

  The active layer 10 is a layer (light emitting layer) that generates light by the combination of carriers (electrons and holes) injected through the n-type electrode 14 and the p-type electrode 15. The n-type cladding layer 11 is disposed between the active layer 10 and the overcoat layer 13. The n-type cladding layer 11 corresponds to “a cladding layer on the light extraction side”. The light extraction side is a side located in the extraction direction when the light generated in the active layer 10 is extracted outside the light emitting element 1. In the case of the light emitting device 1 shown in FIG. 1, the light generated in the active layer 10 is extracted upward. For this reason, the upper side when viewed from the active layer 10 is the light extraction side.

  On the surface of the n-type cladding layer 11, irregularities 16 called texture are formed. The unevenness 16 functions to increase the light transmittance at the interface between the n-type cladding layer 11 and the overcoat layer 13. The concavo-convex 16 has a structure in which a plurality of (many) fine projections having a substantially mountain-shaped cross section are two-dimensionally arranged. The irregularities 16 are formed over the entire surface of the n-type cladding layer 11 except for the site where the n-type contact layer 12 is formed.

  The n-type contact layer 12 is formed directly on the n-type cladding layer 11 (surface). The n-type contact layer 12 is formed in a dot shape at a position where it does not overlap the p-type electrode 15 in plan view. The planar shape of the n-type contact layer 12 is circular. However, the present invention is not limited to this, and the planar shape of the n-type contact layer 12 may be a polygon such as a quadrangle. The dot arrangement of the n-type contact layer 12 is arranged in the Y direction at regular intervals. Further, if a plurality of n-type contact layers 12 arranged in a line in the Y direction are made into one set, the n-type contact layers 12 are divided into a plurality of sets (four sets in the illustrated example) and mutually in the X direction. The positions are shifted and arranged in four rows. Such an arrangement of the n-type contact layer 12 corresponds to a planar shape (wiring pattern shape) of an electrode wiring portion of the n-type electrode 14 described later.

[Detailed configuration of light extraction layer]
The overcoat layer 13 is a layer having a property of transmitting light generated in the active layer 10 (light transmittance). The overcoat layer 13 is laminated directly on the n-type cladding layer 11 so as to cover the surface of the n-type cladding layer 11 (including the irregularities 16). The overcoat layer 13 is made of, for example, silicon nitride.

  The n-type electrode 14 is formed on the upper side when viewed from the active layer 10. For this reason, the n-type electrode 14 corresponds to “an electrode on the light extraction side”. The n-type electrode 14 serves as a negative electrode for injecting carriers (electrons) into the active layer 10 through the n-type cladding layer 11. The n-type electrode 14 includes an electrode wiring part 17, an electrode relay part 18, and an electrode pad part 19.

  The electrode wiring portion 17 is formed in a line shape on the upper surface of the overcoat layer 13. The electrode wiring portion 17 is formed in a wiring pattern with the electrode pad portion 19 as the center. The electrode wiring portion 17 is formed in a state separated from the n-type contact layer 12 in the Z direction (upward). An overcoat layer 13 is interposed between the electrode wiring portion 17 and the n-type cladding layer 11 except for the site where the n-type contact layer 12 is formed. The electrode wiring portion 17 is formed so as not to overlap the above-described dot-shaped p-type electrode 15 in plan view. The electrode wiring portion 17 is arranged in an antenna shape in which one electrode wiring 21 parallel to the X direction and four electrode wirings 22 parallel to the Y direction are combined. Among these, each electrode wiring 22 is formed so as to overlap with the above-described dot-shaped n-type contact layer 12 in a planar manner. Specifically, one electrode wiring 22 is arranged in a state of overlapping in a planar manner with respect to a plurality of n-type contact layers 12 arranged in a line in the Y direction.

  The electrode relay portion 18 is formed directly on the n-type contact layer 12. The electrode relay portion 18 is provided in a 1: 1 relationship with the n-type contact layer 12 at the site where the n-type contact layer 12 is formed. For this reason, in the XY plane of the light emitting element 1, the n-type contact layer 12 and the electrode relay portion 18 are provided in a dot shape with the same arrangement (positional relationship). However, the dot size of the electrode relay portion 18 is set to be smaller than the dot size of the n-type contact layer 12. The electrode wiring 22 of the electrode wiring portion 17 is formed in a line shape so as to bridge a plurality of electrode relay portions 18 arranged in a line in the Y direction with the same dot arrangement as that of the n-type contact layer 12 in the Y direction. . The n-type electrode 14 is formed in a bridge structure by the electrode wiring portion 17 and the electrode relay portion 18. The electrode relay portion 18 is made of metal. If the electrode relay portion 18 is formed of metal, the series resistance of the electrode wiring portion 17 of the n-type electrode 14 and the n-type contact layer 12 can be lowered. The electrode relay portion 18 is an area where the n-type contact layer 12 is formed, and electrically connects the n-type contact layer 12 and the electrode wiring portion 17. That is, the lower end portion of the electrode relay portion 18 is electrically connected to the n-type contact layer 12, and the upper end portion of the electrode relay portion 18 is electrically connected to the electrode wiring portion 17.

  The electrode pad portion 19 is provided in a circular pad shape in plan view in the middle of the line of the electrode wiring 21 of the electrode wiring portion 17. The electrode pad portion 19 is provided at the center in the XY plane of the light emitting element 1. The electrode pad portion 19 is a portion to which a bonding wire such as a gold wire is connected. The pad size of the electrode pad portion 19 is set to be larger than the ball diameter corresponding to the ball diameter of the bonding wire.

<2. Operation of light emitting element>
When operating the light emitting device 1 having the above-described configuration, carriers (electrons) are transferred from the n-type electrode 14 and the p-type electrode 15 to the active layer 10 via the corresponding n-type cladding layer 11 and p-type cladding layer 9. , Holes). At this time, electrons are supplied as carriers from the n-type electrode 14 and holes are supplied as carriers from the p-type electrode 15. In the n-type electrode 14, carriers are supplied to the n-type contact layer 12 through the electrode pad portion 19, the electrode wiring portion 17, and the electrode relay portion 18.

  Thereby, light is emitted by recombination of electron-hole pairs inside the active layer 10 forming a pn junction. At this time, inside the active layer 10, as shown in FIGS. 4A and 4B, a light emission phenomenon occurs immediately above the p-type electrode 15, and light is emitted from the light emission point. Among these, light emitted downward from the light emitting point reaches the reflective metal layer 7 through the p-type cladding layer 9 and the insulating layer 8 while gradually spreading, and is reflected there. Further, light emitted upward from the light emitting point is extracted from the surface of the n-type cladding layer 11 to the outside of the semiconductor layer 3 while gradually spreading. The light reflected by the reflective metal layer 7 is also extracted from the surface of the n-type cladding layer 11 to the outside of the semiconductor layer 3. At this time, if the irregularities 16 are formed on the surface of the n-type cladding layer 11, reflection of light on the surface of the n-type cladding layer 11 can be suppressed. For this reason, more light can be extracted to the outside of the semiconductor layer 3.

  However, of the light generated (radiated) in the active layer 10, part of the light incident on the p-type electrode 15 is absorbed by the p-type electrode 15 and cannot be extracted outside the semiconductor layer 3. In addition, part of the light incident on the n-type contact layer 12 is absorbed by the n-type contact layer 12 and cannot be extracted outside the semiconductor layer 3.

  With respect to such a phenomenon, in the light emitting element 1 described above, the n-type contact layer 12 is formed in a dot shape. For this reason, the total area of the n-type contact layer 12 is smaller when the n-type contact layer is formed in a line than when the n-type contact layer is formed in a line. Therefore, the amount of light absorbed by incidence on the n-type contact layer 12 can be reduced.

  Further, the electrode wiring portion 17 of the n-type electrode 14 is formed at a position spaced upward from the n-type cladding layer 11 with the interposition of the electrode relay portion 18. Further, an overcoat layer 13 is interposed between the electrode wiring portion 17 and the n-type cladding layer 11, and the electrode wiring portion 17 faces the surface of the n-type cladding layer 11 through the overcoat layer 13. For this reason, light can be extracted outside the semiconductor layer 3 even from below the electrode wiring portion 17 except for the site where the n-type contact layer 12 is formed. On the other hand, in the structure of the conventional light emitting element, the line-shaped electrode wiring is also directly overlapped and formed on the line-shaped n-type contact layer. For this reason, light cannot be extracted from under the electrode wiring. Therefore, the light extraction efficiency can be increased as compared with the conventional structure. Furthermore, irregularities 16 can also be formed on the surface of the n-type cladding layer 11 under the electrode wiring portion 17 except for the site where the n-type contact layer 12 is formed. For this reason, it is possible to further increase the light extraction efficiency by expanding the formation region of the irregularities 16.

  In the structure of the conventional light emitting device shown in FIG. 28, a line-shaped n-type contact layer 62 is formed directly on the surface of the n-type cladding layer 61, and the n-type electrode 64 is formed on the n-type contact layer 62. The electrode wiring is directly formed in a line shape. For this reason, as shown in FIG. 5A, when the size of the light spreading region centered on the p-type electrode 65 is defined by the dimension L1, the light that is about to go out of the semiconductor layer is emitted from the n-type contact layer. In order to prevent the light from entering 62 or the n-type electrode wiring 64, the following conditions must be satisfied. That is, it is necessary to set the plane distance between the electrode wiring of the n-type electrode 64 and the p-type electrode 65 closest thereto to the dimension L1.

  On the other hand, in the light emitting element 1 according to the embodiment of the present invention, since the n-type contact layer 12 is formed in a dot shape on the surface of the n-type cladding layer 11, the n-type contact layers adjacent in the Y direction. There is no n-type contact layer 12 between 12 dots. For this reason, as shown in FIG. 5B, the planar distance between the n-type contact layer 12 and the p-type electrode 15 is set to be equivalent to the dimension L1, and the electrode wiring portion 17 of the n-type electrode 14 and The planar distance from the nearest p-type electrode 15 can be reduced to a dimension L2 smaller than the dimension L1. In this case, although a part of the light spreading region overlaps with the wiring region of the electrode wiring portion 17, the n-type contact layer 12 does not exist in the overlapping portion, so that light can be extracted from the semiconductor layer 3 from there. . Furthermore, in the structure of the present invention, since a texture that is advantageous for light extraction can be formed under the electrode wiring portion 17, it is possible to suppress light reflection on the surface of the semiconductor layer 3 and to extract light to the outside as compared with the conventional case. ing. In addition, since the planar distance between the electrode wiring portion 17 of the n-type electrode 14 and the p-type electrode 15 closest thereto is shortened, more p-type electrodes 15 are arranged in the XY plane of the light emitting element 1. Can do. As a result, the forward voltage can be lowered by a decrease in electrical resistance accompanying an increase in the number of electrodes of the p-type electrode 15. When the forward voltage is constant, more carriers can be injected into the active layer 10 to increase the light output.

<3. Manufacturing method of light emitting element>
Then, an example of the manufacturing method of the light emitting element which concerns on embodiment of this invention is demonstrated.

[Manufacturing process of semiconductor layer]
As shown in FIG. 6A, an etching stopper layer 101, an n-type contact layer 102, an n-type cladding layer 103, an active layer 104, p, and the like are formed on a growth substrate 100 made of an n-type GaAs substrate by, for example, MOCVD. A mold cladding layer 105 is formed by growing in this order. MOCVD is an abbreviation for “Metal Organic Chemical Vapor Deposition”.

  Next, as shown in FIG. 6B, an insulating layer 106 is formed on the surface (upper surface) of the p-type cladding layer 105. The insulating layer 106 is formed, for example, by depositing SiO 2 having a thickness of λ / 4n by the CVD method.

  Next, as illustrated in FIG. 7A, a resist 107 is formed so as to cover the insulating layer 106, and then the resist 107 is exposed and developed, whereby a through hole 108 is formed in the resist 107. The through holes 108 are formed corresponding to the dot arrangement of the p-type electrode 15. Next, the insulating film 106 is wet etched using the resist 107 as a mask. Thereby, a part of the insulating film 106 is removed through the through hole 108 of the resist 107. Part of the insulating film 106 removed by wet etching becomes a contact hole.

  Next, as shown in FIG. 7B, a metal layer 109 is formed by depositing, for example, a Ti (titanium) layer and an AuZn (gold-zinc) alloy layer in this order on the resist 107. Thereafter, the resist 107 is removed. As a result, a part 109 a of the metal layer 109 remains in the contact hole of the insulating film 106 as an electrode part constituting the p-type electrode 15.

  Next, as shown in FIG. 8A, a metal layer 110 is formed on the entire surface of the insulating film 106 (including the contact hole portion) by an evaporation method. The metal layer 110 is formed by stacking, for example, an Al layer, an Au layer, a Ti layer, a Pt (platinum) layer, and an Au layer in this order on the insulating film 106.

[Manufacturing process of bonded substrates]
As shown in FIG. 8B, a metal layer 112 is formed by vapor deposition on the entire surface of one side of a support substrate 111 made of an n-type GaAs substrate. The metal layer 112 is formed on the support substrate 11 by, for example, stacking an AuGe layer, a Ni layer, an Au layer, a Ti layer, a Pt layer, and an Au layer in this order.

[Board bonding process]
Next, as shown in FIG. 9, the growth substrate 100 and the support substrate 111 are pasted in a state where the metal layer 110 formed on the growth substrate 100 side and the metal layer 112 formed on the support substrate 111 side face each other. Match. The substrates are bonded together by pressurizing (bonding) the substrates at a high temperature of about 400 ° C., for example.

[Post-process]
Next, as shown in FIG. 10A, the growth substrate 100 is removed by lapping. As a result, the etching stopper layer 101 is exposed to the outside.

  Next, as shown in FIG. 10B, the etching stopper layer 101 is removed by wet etching. As a result, the n-type contact layer 102 is exposed to the outside.

  11A, the reflective metal layer 132, the insulating layer 106, the p-type cladding layer 105, the active layer 104, the n-type cladding layer 103, and the n-type contact layer are formed on the support substrate 111. A structure in which 102 is laminated in this order is obtained. Among these, the p-type electrode 131 is formed on the insulating layer 106. The p-type electrode 131 is formed by the metal layers 109a and 110 described above. The reflective metal layer 132 is formed by the metal layers 110 and 112 described above.

[Step of forming light extraction layer]
Next, as shown in FIG. 11B, an insulating layer 113 is formed over the entire surface of the n-type contact layer 102. The insulating layer 113 is formed by depositing, for example, SiO2 by a CVD method so as to cover the n-type contact layer 102.

  Next, as illustrated in FIG. 12A, a resist 114 is formed over the insulating layer 113. The resist 114 is formed into a pattern corresponding to the dot arrangement of the n-type contact layer 12 and the pad shape of the electrode pad portion 19 through the steps of application of resist material, exposure and development.

  Next, as illustrated in FIG. 12B, the insulating layer 113 is etched using the resist 114 as a mask. When the insulating layer 113 is formed of SiO2, the SiO2 is etched with HF liquid. When the etching is finished, the resist 114 is removed.

  Next, as shown in FIG. 13A, the n-type contact layer 102 is etched using the etched insulating layer 113 as a hard mask. When the n-type contact layer 102 is formed of GaAs, the n-type contact layer 102 is etched with an NH3 + H2O2 solution. Thereby, the n-type contact layer 102 is processed into a dot shape.

  Next, as shown in FIG. 13B, a resist 115 is formed on the n-type cladding layer 103. The resist 115 is formed into a pattern corresponding to the structure of the projections and depressions 16 through steps of application of resist material, exposure, and development.

  Next, as shown in FIG. 14A, the n-type cladding layer 103 is etched using the resist 115 as a mask. For etching the n-type cladding layer 103, sulfuric acid water is used. Thereby, unevenness (texture) 116 is formed on the surface of the n-type cladding layer 103.

  Next, as shown in FIG. 14B, after the resist 115 is removed, the insulating film 113 covering the n-type contact layer 102 is removed by etching. An HF liquid is used for etching the insulating film 113.

  Next, although not shown, a resist pattern is formed on the n-type clad layer 103 by applying a resist material, exposing and developing. At this time, a through hole is formed in the resist at the site where the n-type contact layer 12 is formed and the site where the electrode pad portion 19 is formed.

  Next, after depositing, for example, an AuGe layer, a Ni layer, and an Au layer in this order on the resist covering the n-type cladding layer 103, unnecessary metal layers are removed together with the resist. Thereby, as shown in FIG. 15A, a metal layer 117 is formed on the n-type contact layer 102 corresponding to the formation site of the n-type contact layer 12 and the formation site of the electrode pad portion 19. Is done. It should be noted that the n-type contact layer 102 may or may not be present at the site where the electrode pad portion 19 is formed.

  Next, as shown in FIG. 15B, a resist 118 is formed on the n-type cladding layer 103. The resist 118 is formed into a pattern corresponding to the dot arrangement of the n-type contact layer 102 through the steps of application of resist material, exposure, and development. As a result, the surface of the metal layer 117 is exposed through the opening of the resist 118.

  Next, as shown in FIG. 16A, for example, a Ti layer, a Pt layer, and an Au layer are sputter-deposited in this order on the resist 118 covering the n-type cladding layer 103, thereby forming the base metal layer 119. Form.

  Next, as illustrated in FIG. 16B, a resist 120 is formed over the base metal layer 119. The resist 120 is formed into a pattern corresponding to the wiring pattern of the electrode wiring portion 17 through the steps of application of resist material, exposure, and development. As a result, an opening groove is formed in the resist 120 corresponding to the formation site of the electrode wiring portion 17.

  Next, as shown in FIG. 17A, the metal wiring part 121 is formed by plating and growing Au on the base metal layer 119 in the opening groove portion of the resist 120.

  Next, as shown in FIG. 17B, after the resist 120 is peeled off, the base metal layer 119 attached to the portion excluding the formation portion of the electrode wiring portion 17 is removed by ion milling. As a result, an n-type electrode having a bridge structure is formed on the n-type contact layer 102 by the base metal layer 119 and the metal wiring part 121.

  Next, as shown in FIG. 18A, the resist 118 is removed. As a result, the resist 118 existing between the metal wiring part 121 and the n-type cladding layer 103 is removed. For this reason, an air bridge structure in which a space is interposed under the metal wiring part 121 is realized.

  Next, as shown in FIG. 18B, an overcoat layer 122 is formed. The overcoat layer 122 is formed, for example, by depositing silicon nitride by a CVD method, so that the surface of the n-type cladding layer 103, the n-type contact layer 102, the metal layer 117, the base metal layer 119, and the metal formed thereon are formed. It is formed so as to cover the surface of the wiring part 121 and the like.

  Next, although not shown, a resist (not shown) pattern is formed on the overcoat layer 122 by application of resist material, exposure, and development. At this time, the resist is opened at the site where the electrode pad portion 19 is formed.

  Next, the overcoat layer 122 is etched by a dry etching method using a resist covering the overcoat layer 122 as a mask. As a result, as shown in FIG. 19A, a part 121a of the metal wiring part 121 is exposed in a pad shape at the portion where the electrode pad part 19 is formed.

  Next, after wrapping the support substrate 111 to a total film thickness of about 100 μm, as shown in FIG. 19B, for example, an AuGe layer, a Ni layer, and an Au layer are formed on the back surface of the support substrate 111 in this order. By depositing the entire surface, the metal layer 123 is formed.

  In the light-emitting element obtained by the above manufacturing process, the metal layer 123 corresponds to the ohmic metal layer 5, the support substrate 111 corresponds to the support substrate 6, the reflective metal layer 132 corresponds to the reflective metal layer 7, and the insulating layer 106. Corresponds to the insulating layer 8. The p-type electrode 131 corresponds to the p-type electrode 15, the p-type cladding layer 105 corresponds to the p-type cladding layer 9, and the active layer 114 corresponds to the active layer 10. The n-type cladding layer 103 corresponds to the n-type cladding layer 11, the unevenness 106 corresponds to the unevenness 16, and the n-type contact layer 102 corresponds to the n-type contact layer 12. The metal layer 117, the base metal layer 119, and the metal wiring portion 121 constitute the n-type electrode 14 (electrode wiring portion 17, electrode relay portion 18, electrode pad portion 19), and the overcoat layer 122 is the overcoat layer 13. It is equivalent to.

  Subsequently, another example of the method for manufacturing the light emitting element according to the embodiment of the present invention will be described.

  First, the support substrate 111, the reflective metal layer 132, the insulating layer 106, the p-type cladding layer 105, the active layer 104, and the n-type cladding layer 103 are laminated in this order by performing the same processes as in FIGS. The obtained structure is obtained. A p-type electrode 131 is provided in a dot shape on the insulating layer 106 of this structure. Further, the n-type contact layer 102 is formed in a dot shape on the n-type clad layer 103, and irregularities 106 are formed on the surface of the n-type clad layer 103 except for the portion where the n-type contact layer 102 is formed. .

  Next, although not shown, a resist pattern is formed on the n-type clad layer 103 by applying a resist material, exposing and developing. At this time, a through hole is formed in the resist at the site where the n-type contact layer 12 is formed.

  Next, after depositing, for example, an AuGe layer, a Ni layer, and an Au layer in this order on the resist covering the n-type cladding layer 103, unnecessary metal layers are removed together with the resist. As a result, as shown in FIG. 20A, a metal layer 117 is formed on the n-type contact layer 102 corresponding to the formation site of the n-type contact layer 12. It should be noted that the n-type contact layer 102 may or may not be present at the site where the electrode pad portion 19 is formed.

  Next, as shown in FIG. 20B, a transparent conductive film 140 is formed on the n-type cladding layer 103. The transparent conductive film 140 is formed, for example, by sputtering vapor deposition of ITO (Indium Tin Oxide) on the entire surface of the n-type cladding layer 103 (including the formation site of the n-type contact layer 102 and the metal layer 117).

  Next, as illustrated in FIG. 21A, a resist 141 is formed over the transparent conductive film 140. The resist 141 is formed into a pattern corresponding to the wiring pattern of the electrode wiring portion 17 through the steps of application of resist material, exposure, and development.

  Next, as shown in FIG. 21B, the transparent conductive film 140 is dry-etched using the resist 141 as a mask. Thereby, the surface of the metal layer 117 is exposed.

  Next, as shown in FIG. 22A, after the resist 141 is removed, a resist 142 is formed over the transparent conductive film 140.

  Next, as shown in FIG. 22B, for example, a Ti layer, a Pt layer, and an Au layer are sputter-deposited in this order from the transparent conductive film 140 to form the metal wiring part 143.

  Next, as shown in FIGS. 23A and 23B, after the resist 142 is peeled off, an overcoat layer (not shown) is formed so as to cover the metal wiring part 143 on the transparent conductive film 140 as necessary. ). When the overcoat layer is formed, the electrode pad portion 19 is opened by etching. The metal wiring part 143 is formed in an H-shaped wiring pattern including the formation part of the electrode pad part 19. As a result, an n-type electrode having a bridge structure is formed on the n-type contact layer 102 by the metal layer 117 and the metal wiring portion 143.

  Next, after wrapping the support substrate 111 to a total film thickness of about 100 μm, for example, an AuGe layer, a Ni layer, and an Au layer are vapor-deposited in this order on the back surface of the support substrate 111 as shown in FIG. Thereby, the metal layer 144 is formed.

  In the light-emitting element obtained by the above manufacturing process, the metal layer 144 corresponds to the ohmic metal layer 5, the support substrate 111 corresponds to the support substrate 6, the reflective metal layer 132 corresponds to the reflective metal layer 7, and the insulating layer 106. Corresponds to the insulating layer 8. The p-type electrode 131 corresponds to the p-type electrode 15, the p-type cladding layer 105 corresponds to the p-type cladding layer 9, and the active layer 114 corresponds to the active layer 10. The n-type cladding layer 103 corresponds to the n-type cladding layer 11, the unevenness 106 corresponds to the unevenness 16, and the n-type contact layer 102 corresponds to the n-type contact layer 12. The transparent conductive film 140 is a film formed on the n-type cladding layer 103 instead of the overcoat layer 13. The metal layer 117 and the metal wiring portion 143 constitute the n-type electrode 14 (electrode wiring portion 17, electrode relay portion 18, electrode pad portion 19).

  In the light emitting device obtained by such a manufacturing process, as can be seen from FIG. 23B, the metal wiring portion 143 constituting the electrode wiring portion 17 of the n-type electrode 14 is formed in an H shape instead of an antenna shape. . In addition, the metal wiring part 143 is a contact disposed on a part of the contact layer 102 formed in a dot shape in the plane of the light emitting element, more preferably on a side relatively far from the electrode pad part. It is formed so as to overlap with the layer 102 in a planar manner. For this reason, the wiring area of the n-type electrode 14 can be reduced as compared with the case where the metal wiring portion 143 is formed so as to overlap with all the contact layers 102 in a planar manner. In addition, for the contact layer 102 disposed on the side far from the electrode pad portion, the carrier passes through the metal wiring portion 143 and the metal layer 117 constituting the n-type electrode 14 (particularly, the electrode wiring portion 17 and the electrode relay portion 18). Can be supplied. Further, carriers can be supplied to the contact layer 102 disposed on the side close to the electrode pad portion through the transparent conductive film 140. Further, since the surface of the n-type clad layer 103 is covered with the transparent conductive film 140 and the metal wiring portion 143 constituting the electrode wiring portion 17 is formed on the surface of the transparent conductive film 140, the n-type electrode is supplied. Carriers can be diffused by the transparent conductive film 140.

  In the above embodiment, the light emitting element in which the light extraction side electrode is an n-type electrode has been described as an example. However, the present invention is not limited to this, and the light extraction side electrode is a p-type electrode. You may apply to a light emitting element.

<4. Application example>
The present invention can be applied to electronic devices such as a lighting device and a display device, for example. In application to a lighting device, the above light-emitting element can be used as the light source. In application to a display device, for example, the above light emitting element can be used as a light source of a backlight of a liquid crystal display device.

  DESCRIPTION OF SYMBOLS 1 ... Light emitting element, 2 ... Support layer, 3 ... Semiconductor layer, 4 ... Light extraction layer, 6 ... Support substrate, 7 ... Reflective metal layer, 8 ... Insulating layer, 9 ... P-type clad layer, 10 ... Active layer, 11 ... n-type cladding layer, 12 ... n-type contact layer, 13 ... overcoat layer, 14 ... n-type electrode, 15 ... p-type electrode, 16 ... unevenness, 17 ... electrode wiring part, 18 ... electrode relay part, 19 ... electrode Pad part

Claims (8)

An active layer,
A pair of cladding layers sandwiching the active layer;
Of the pair of clad layers, a contact layer formed in a dot shape on the light extraction side clad layer, and
A light extraction side electrode electrically connected to the contact layer,
The electrode on the light extraction side is
An electrode wiring part formed in a state of being spaced apart from the contact layer in the thickness direction of the light emitting element and overlapping the contact layer in a plane;
A light emitting element formed of a bridge structure including an electrode relay portion that electrically connects the contact layer and the electrode wiring portion at a portion where the contact layer is formed. The light emitting device according to claim 1, wherein unevenness is formed on a surface of the cladding layer on the light extraction side and excluding a portion where the contact layer is formed. A transparent conductive film covering a surface of the cladding layer on the light extraction side;
The light emitting device according to claim 1, wherein the electrode wiring portion is formed on a surface of the transparent conductive film. The light emitting element according to claim 1, wherein the electrode relay portion is made of metal. The light-emitting element according to claim 3, wherein the electrode wiring portion is formed in a state of planarly overlapping a part of the contact layer formed in the dot shape. The light extraction side electrode has an electrode pad portion for wire bonding,
The light emitting element according to claim 5, wherein the part of the contact layer is a contact layer disposed on a side relatively far from the electrode pad portion. Producing a structure in which a reflective metal layer, an insulating layer, a first cladding layer, an active layer, a second cladding layer, and a contact layer are stacked in this order on a support substrate, and a first electrode is formed on the insulating layer; ,
Processing the contact layer into dots,
Forming a second electrode with a bridge structure on the contact layer. An active layer,
A pair of cladding layers sandwiching the active layer;
Of the pair of clad layers, a contact layer formed in a dot shape on the light extraction side clad layer, and
A light extraction side electrode electrically connected to the contact layer,
The electrode on the light extraction side is
An electrode wiring portion formed in a state of being spaced apart from the contact layer in the thickness direction of the light emitting element and overlapping the contact layer in a plane;
An electronic device using a light-emitting element that is formed in a bridge structure including: an electrode relay portion that electrically connects the contact layer and the electrode wiring portion at a portion where the contact layer is formed.

Images