JP2012227311A - Semiconductor light-emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor light-emitting element having improved light extraction efficiency.SOLUTION: A semiconductor light-emitting element according to the present invention comprises a semiconductor layer, a first electrode arranged on a top face of the semiconductor layer and a second electrode arranged on an undersurface of the semiconductor layer. The top face of the semiconductor layer includes a first region and a second region having a thickness of the semiconductor layer thicker than that of the first region. The first electrode includes a pad electrode and an auxiliary electrode extending from the pad electrode. The first electrode is located on the second region and the second region includes a region along the auxiliary electrode and a region extending in a direction different from the auxiliary electrode.

Description

  The present invention relates to a semiconductor light emitting device.

  In a semiconductor light emitting device having semiconductor layers of different conductivity types with a light emitting layer interposed therebetween, a technique for improving light extraction efficiency is known. As a conventional technique, in a vertical structure gallium nitride-based LED element, a part of light emitted from the light-emitting layer is formed by forming a p-electrode surface formed on the lower surface of the light-emitting layer and the p-type gallium nitride layer into an uneven profile. Light extraction efficiency is improved by minimizing the absorption or scattering of light by being absorbed or scattered by the p-electrode and forming the n-type reflective electrode on the lower surface of the n-type bonding pad formed on the top of the LED element Is disclosed. Furthermore, an n-type transparent electrode can be provided at the interface between the n-type reflective electrode and the n-type gallium nitride layer to improve the current diffusion phenomenon (see, for example, Patent Document 1).

JP 2007-142420 A

  However, even if the electrode is made of a highly reflective metal and has an uneven shape, the metal has a light absorbing action, and there is a concern that there is light that is absorbed every time reflection is repeated.

  In addition, considering that light from the light emitting layer is absorbed not only by the electrode but also by the semiconductor layer itself, the thinner the semiconductor layer in the stacking direction, the more effective the light extraction. However, when the semiconductor layer is thinned, the current spreading effect in the lateral direction is reduced.

  Therefore, the present invention has been made to solve such problems. An object of the present invention is to provide a semiconductor light emitting device with improved light extraction efficiency.

  According to the present invention, the above problem is solved by the following means.

  A semiconductor light emitting device according to the present invention is a semiconductor light emitting device comprising a semiconductor layer, a first electrode disposed on an upper surface of the semiconductor layer, and a second electrode disposed on a lower surface of the semiconductor layer, The upper surface of the semiconductor layer has a first region and a second region in which the semiconductor layer is thicker than the first region. The first electrode is a pad electrode and an auxiliary electrode extending from the pad electrode. The first electrode is on the second region, and the second region has one along the auxiliary electrode and one extending in a different direction from the auxiliary electrode. As a result, a semiconductor light emitting device having a current spreading effect and improved light extraction efficiency can be obtained.

  The semiconductor light emitting device preferably includes a plurality of the second regions and is connected to each other. Thereby, the current spreading effect can be further improved.

  Moreover, it is preferable that what the said semiconductor light-emitting element extends | stretches in a different direction from the said auxiliary electrode is perpendicular | vertical with respect to the thing along the said auxiliary electrode. As a result, current can be efficiently diffused to portions other than the electrode portion.

  The semiconductor light emitting device preferably includes a plurality of the second regions and is arranged in a stripe shape. Thereby, since the semiconductor layer is thin in a portion other than the second region, that is, in the first region, absorption of light from the light emitting layer can be suppressed and light can be extracted efficiently.

  In the semiconductor light emitting device, the upper surface of the semiconductor layer is preferably a rough surface. Thereby, the light extraction efficiency can be further improved, and the adhesion between the semiconductor layer and the electrode can be improved.

In the semiconductor light emitting device, the semiconductor layer has a p-type and an n-type nitride semiconductor layer,
The second region is preferably provided on the n-type nitride semiconductor layer. Thereby, it can be set as a low voltage semiconductor light emitting element.

  According to the semiconductor light emitting device of the present invention, a semiconductor light emitting device with improved light extraction efficiency can be provided.

It is a schematic plan view which shows the electrode, 1st area | region, and 2nd area | region of the semiconductor light-emitting device concerning 1st embodiment. 1 is a schematic cross-sectional view showing a semiconductor light emitting element according to a first embodiment. 1 is a schematic cross-sectional view showing a semiconductor light emitting element according to a first embodiment. It is a schematic plan view which shows the electrode, 1st area | region, and 2nd area | region of the semiconductor light-emitting device concerning 2nd embodiment. It is a schematic sectional drawing which shows the electrode, 1st area | region, and 2nd area | region of the semiconductor light-emitting device concerning 2nd embodiment. It is a schematic plan view which shows the electrode, 1st area | region, and 2nd area | region of the semiconductor light-emitting device concerning 3rd embodiment. It is a schematic plan view which shows the electrode, 1st area | region, and 2nd area | region of the semiconductor light-emitting device concerning 4th embodiment. It is a schematic plan view which shows the electrode, 1st area | region, and 2nd area | region of the semiconductor light-emitting device concerning 5th embodiment. It is a schematic plan view which shows the electrode, 1st area | region, and 2nd area | region of the semiconductor light-emitting device concerning 6th embodiment. It is a schematic plan view which shows the electrode, 1st area | region, and 2nd area | region of the semiconductor light-emitting device concerning 7th embodiment. It is the photograph which image | photographed the semiconductor light-emitting device concerning Example 1 and a reference example from the upper surface with the optical microscope. It is an image figure which shows the light emission intensity distribution of the semiconductor light-emitting element which concerns on Example 1, a reference example, and a comparative example. It is a graph which shows the optical output and forward voltage when the semiconductor light-emitting device which concerns on Example 1, a reference example, and a comparative example is driven by the forward current 350mA.

  A mode for carrying out the present invention will be described below with reference to the drawings. However, the embodiment described below exemplifies a semiconductor light emitting device and a method for manufacturing the same for embodying the technical idea of the present invention, and does not limit the present invention.

In addition, in the present specification, the members shown in the claims are not limited to the members of the embodiments. The dimensions, materials, shapes, relative arrangements, and the like of the component parts described in the embodiments are not intended to limit the scope of the present invention only to the description unless otherwise specified. Not too much. Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. Furthermore, in the following description, the same name and symbol indicate the same or the same members, and detailed description thereof will be omitted as appropriate. Furthermore, each element constituting the present invention may be configured such that a plurality of elements are constituted by the same member and the plurality of elements are shared by one member, and conversely the function of one member is constituted by a plurality of members. It can also be realized by sharing.
Further, in this specification, the term “upper” on a layer or the like is not necessarily limited to the case where it is formed in contact with the upper surface, but includes the case where it is formed on the upper side while being separated. It is used in the meaning including the case where there is a member interposed between them.

<First embodiment>
The first embodiment will be described in detail with reference to the drawings. FIG. 1 is a schematic plan view showing an electrode, a first region, and a second region of the semiconductor light emitting device according to the first embodiment. 2 and 3 are schematic cross-sectional views of the semiconductor light emitting device according to the first embodiment. FIG. 2 is a cross-sectional view taken along the line AA ′ in FIG. 1, and FIG. 3 is a cross-sectional view taken along the line BB ′ in FIG. Cross-sectional views are shown respectively.

  The semiconductor light emitting device 100 according to the first embodiment includes a support base 103, a semiconductor layer 12 positioned above the support base 103, a first electrode 15 and a second electrode 16 that vertically narrow the semiconductor layer 12. , Mainly composed. The support base 103 is fixed by laminating the support substrate 104 and the adhesive layer 105 in this order. On the other hand, the semiconductor layer 12 includes a light emitting layer 113, an n-type semiconductor layer that is a first conductive semiconductor layer 111 and a p-type semiconductor layer that is a second conductive semiconductor layer 112 stacked with the light emitting layer 113 interposed therebetween. And have. In the semiconductor light emitting device 100, the second conductive semiconductor layer 112, the light emitting layer 113, and the first conductive semiconductor layer 111 are stacked in this order to form the semiconductor layer 12, and are positioned above the semiconductor layer 12. The first conductivity type semiconductor layer 111 side is a main light emitting surface side of light emitted from the light emitting layer 113, that is, a light extraction side.

  The first electrode 15 and the second electrode 16 supply power to the first conductive semiconductor layer 111 and the second conductive semiconductor layer 112, respectively. Specifically, an n-electrode that is the first electrode 15 is formed in the n-type semiconductor layer, and power can be supplied. Similarly, a p-electrode that is the second electrode 16 is formed on a part of the main surface of the p-type semiconductor layer.

  The first electrode 15 and the second electrode 16 are arranged so as not to overlap each other when the semiconductor layer 12 is viewed in plan. In other words, the second electrode 16 is arranged not to be partly or entirely arranged in a region facing the first electrode 15 with the semiconductor layer 12 interposed therebetween. For this reason, the second electrode 16 is insulated by laminating a region separated from the adjacent second electrode 16 with the protective film 107.

  In the plan view from the light extraction side of the semiconductor light emitting device 100, the formation pattern of the first electrode 15 on the first conductivity type semiconductor layer 111 is mainly illustrated. The first electrode 15 is formed on the upper surface of the square semiconductor layer 12, the auxiliary electrode 11 that is an extension part of a pair of linear electrodes, and an external electrode disposed so as to overlap a part of each auxiliary electrode 11. It is comprised by the pad electrode 10 which can be connected with a power supply. In the specification of the present invention, the semiconductor layer side on which the pad electrode is formed is the upper surface.

  In the plan view of the semiconductor light emitting device 100, a pair of linear auxiliary electrodes 11 are arranged in parallel on a square semiconductor layer 12, and a pair of pad electrodes 10 are arranged diagonally thereon. The pair of pad electrodes 10 and the auxiliary electrode 11 are arranged substantially symmetrically with respect to the center connecting the diagonal lines of the semiconductor layer 12 and are separated from each other without crossing each other. It is an interval. The shape of the auxiliary electrode 11 is an unbranched line, and is formed in an elongated continuous shape. Thus, by arranging the external power supply regions symmetrically, current diffusion to the entire surface of the semiconductor layer 12 can be efficiently realized. In addition, it is possible to suppress concentration of current and heat generation at each part of the connection part with the external power supply, and the intersection and the bent part, preferably by having a part of the electrode separated, preferably having no intersection and a bent part. The uniformity of current density and the heat dissipation function can be improved.

  In the first embodiment, one pad electrode 10 is provided for each of the pair of parallel auxiliary electrodes 11, but a plurality of pad electrodes 10 may be provided on one auxiliary electrode 11 or the semiconductor layer 12. For example, in addition to being arranged linearly on the semiconductor layer 12 so as to function similarly to the auxiliary electrode 11, it may be arranged in a zigzag shape or the like.

  The extent of extension of the auxiliary electrode 11 is not limited to the above range, and the auxiliary electrode 11 may be provided with a length corresponding to one side of the semiconductor layer 12 in a top view. The electrode arrangement extended until the auxiliary electrode 11 reaches the peripheral edge of the semiconductor layer 12 can further increase the arrangement ratio of the auxiliary electrode 11 with respect to the semiconductor layer 12 without having an intersection, thereby suppressing the uneven distribution of current. However, the current can be injected, and the luminous efficiency is increased.

  The upper surface of the first conductivity type semiconductor layer 111 includes a first region 14 and a second region 13 in which the semiconductor layer 12 is thicker than the first region 14. The thickness of the second region 13 may not be constant, and the first electrode 15 having the pad electrode 10 and the auxiliary electrode 11 is provided on the second region 13. The second region 13 includes a portion along the auxiliary electrode 11 in a top view and a portion exposed from the auxiliary electrode 11 by extending in a different direction from the auxiliary electrode 11. The fact that the second region 13 is along the auxiliary electrode 11 in a top view has substantially the same shape as the outer edge shape of the auxiliary electrode 11 and may be exposed from the outer edge of the auxiliary electrode 11. In the present invention, the second region 13 that extends in a direction different from the auxiliary electrode 11 and is exposed from the auxiliary electrode 11 may be referred to as an “extension portion”. In the present embodiment, a plurality of extending portions perpendicular to the auxiliary electrode 11 in a top view are formed in a stripe shape, and reach the peripheral portion of the semiconductor layer 12.

  The width of the extension part in the top view is 3 to 20 μm, preferably 5 to 10 μm, but is not particularly limited, and the extension part itself or the tip of the extension part is square, triangular, circular, or circular Any shape such as a shape or a wave shape can be used. Further, the width and shape of the first region 14 in a top view are not particularly limited as in the extended portion, and may be one long shape that is rectangular along the extending direction of the auxiliary electrode 11. Furthermore, when there are a plurality of extending portions, the extending portions at distant positions may be connected to each other, and at this time, the shape of the extending portion is a stripe, rhombus, hexagon, concentric circle in top view It is also possible to make them equal. As long as it has a stripe shape, it may be arranged perpendicularly to the pad electrode or auxiliary electrode or obliquely with an angle other than perpendicular. When arranged obliquely at an angle other than vertical, it is preferable that the angle be such that the distance between the two pad electrodes 10 that are substantially point-symmetric is close.

  The current from the second electrode 16 is diffused in the lateral direction and reaches the first electrode 15 as the thickness of the semiconductor layer 12 increases. Since the semiconductor layer 12 is thicker in the extension part than in the first region 14, the current is prevented from becoming dense at the first electrode 15 in the vicinity of the extension part, and the voltage is lowered. On the other hand, when the first region 14 is formed around the first electrode 15, the light from the light emitting layer 113 is absorbed by the semiconductor layer 12 because the semiconductor region 12 is thinner than the extending portion of the first region 14. The light extraction efficiency is improved. As described above, by arranging the extending portion having the current diffusion effect and the first region 14 having the effect of suppressing the light absorption from the light emitting layer in the vicinity of the stripe shape, the current can be efficiently supplied to the entire semiconductor layer 12. While being able to diffuse, light extraction efficiency can be improved. In addition, the vicinity of the pad electrode 10 and the vicinity of the auxiliary electrode 11 are inevitably high in current density because current is supplied from the external power source to the semiconductor light emitting element 100 through the conductive member. The strength is particularly strong. Therefore, the effect of the present invention is more exhibited around the first electrode 15.

  On the upper surface of the semiconductor layer 12, the side surfaces of the semiconductor layer 12 forming the second region 13 and the first region 14 may be vertical or have an angle other than vertical. Further, the upper surface of the semiconductor layer 12 may be a rough surface having fine irregularities on the surface regardless of the second region 13 and the first region 14. Thereby, the adhesiveness between the semiconductor layer 12 and the electrode 15 is improved, and the light extraction efficiency is further improved.

  In the semiconductor light emitting device 100, the semiconductor layer 12 includes a p-type nitride semiconductor layer and an n-type nitride semiconductor layer, and the first region 14 and the second region 13 are formed on the n-type nitride semiconductor layer. In this case, since the n-type nitride semiconductor layer has a smaller electrical resistance than the p-type nitride semiconductor layer and suppresses a voltage rise, a lower-voltage semiconductor light emitting element can be obtained.

<Second Embodiment>
Next, the semiconductor light emitting device according to the second embodiment will be described. FIG. 4 is a schematic plan view showing an electrode, a first region, and a second region of the semiconductor light emitting device according to the second embodiment. FIG. 5 is a schematic cross-sectional view showing the electrodes, the first region, and the second region of the semiconductor light emitting device according to the second embodiment, and shows a cross-sectional view taken along the line CC ′ of FIG. The semiconductor light emitting device 200 according to the second embodiment is substantially the same as the first embodiment except that the pad electrode 20 and the auxiliary electrode 21 are provided on the second region 23 and the first region 24. .

  The semiconductor light emitting device 200 according to the second embodiment includes an electrode 25 including a pad electrode 20 and an auxiliary electrode 21 on a semiconductor layer 22, and the electrode 25 is not only on the second region 23 but also on the first region 24. Is also provided. As a result, the electrode 25 is also formed on the side surface of the second region 23, the contact area with the electrode is increased, and the contact resistance can be lowered. Further, the cross-sectional shape of the electrode 25 may be uneven or flat as in the second region 23 and the first region 24.

<Third embodiment>
Next, a semiconductor light emitting device according to a third embodiment will be described. FIG. 6 is a schematic plan view showing the electrodes, the first region, and the second region of the semiconductor light emitting device according to the third embodiment. The semiconductor light emitting device 300 according to the third embodiment is substantially the same as the first embodiment except that the structure of the electrode 35 is different.

The semiconductor light emitting device 300 according to the third embodiment has an electrode 35 including a pad electrode 30 and an auxiliary electrode 31 extending from the pad electrode 30 on the semiconductor layer 32.
The semiconductor light emitting device 300 has three parallel auxiliary electrodes 31 on the semiconductor layer 32, and one pad electrode 30 is provided so as to overlap the two outer auxiliary electrodes 31. Of the three parallel auxiliary electrodes 31, an auxiliary electrode that connects the inner auxiliary electrode 31 and the outer pad electrode 30 can be provided. When the pad electrode 30 is located at the intersection of the plurality of auxiliary electrodes 31 having different extending directions, the intersection between the intersection and the pad electrode 30 that may occur when the intersection of the plurality of auxiliary electrodes 31 and the pad electrode 30 are separated from each other. The current concentration in the can be relaxed and problems such as heat generation can be effectively avoided. As described above, the auxiliary electrode 31 intersects and branches to connect the pad electrode 30 and the auxiliary electrode 31, thereby increasing the electrode area and making the current distribution uniform. In addition, it is possible to avoid a situation in which the auxiliary electrodes intersect in a cross shape and current concentrates at the intersection.

  The auxiliary electrode 31 is reduced in a similar relationship to the top view shape of the semiconductor layer 32 by crossing, branching, or bending, that is, a shape connected in a substantially square shape, or a corner of the auxiliary electrode 31 is bent at a substantially right angle. A shape having a bent portion or a shape having a region where the semiconductor layer 32 is surrounded by the auxiliary electrode 31 can be used. However, in the surrounding region by the auxiliary electrode 31 as described above, current concentrates in the vicinity of the electrode and the light emission intensity increases, and heat storage increases in that portion. Therefore, a semiconductor light emitting device having no surrounding region by the auxiliary electrode 31 is preferable because it can realize current uniformity and light emission uniformity, is excellent in heat dissipation, and has high resistance even under a large current.

<Fourth embodiment>
Next, a semiconductor light emitting element according to a fourth embodiment will be described. FIG. 7 is a schematic plan view showing the electrodes, the first region, and the second region of the semiconductor light emitting device according to the fourth embodiment. The semiconductor light emitting device 400 according to the fourth embodiment is substantially the same as the third embodiment except that the shape and arrangement of the second region 43 and the first region 44 on the upper surface of the semiconductor layer 42 are different. is there.

  The semiconductor light emitting device 400 according to the fourth embodiment is provided with an extending portion including the second region 43 only around the electrode 45. The extending portion may be provided all around the electrode 45 or may be provided on a part of the periphery of the electrode 45. The shape, width, size, and the like of the extending portion are not particularly limited, and all of them need not be the same. In the vicinity of the pad electrode 40 and the vicinity of the auxiliary electrode 41, current is supplied from the external power source to the semiconductor light emitting element 400 via the conductive member, so that the current density is inevitably high and the light emission intensity is high. Especially strong. Therefore, by arranging the extending portion and the first region 44 around the electrode 45, the effect of efficiently diffusing the current to the entire semiconductor layer 42 and suppressing the absorption of light from the light emitting layer is more exhibited. Is done.

  In the fourth embodiment, the extending portion has a rectangular shape, but the length in the longitudinal direction of the extending portion is preferably 30 to 50 μm in top view. Thereby, in addition to the extension part for current diffusion, the area of the thin first region 44 of the semiconductor layer 42 increases, so that the light absorbed by the semiconductor layer is reduced and the light emission efficiency is improved. That is, if the area of the extended portion in the top view is reduced, a semiconductor light emitting device with higher output can be obtained.

<Fifth embodiment>
Next, a semiconductor light emitting element according to a fifth embodiment will be described. FIG. 8 is a schematic plan view showing the electrodes, the first region, and the second region of the semiconductor light emitting device according to the fifth embodiment. The semiconductor light emitting device 500 according to the fifth embodiment is substantially the same as the third or fourth embodiment except that the shape and arrangement of the second region 53 and the first region 54 on the upper surface of the semiconductor layer 52 are different. The same as above.

  The semiconductor light emitting device 500 according to the fifth embodiment is provided with an extending portion including the second region 53 only around the electrode 55. A plurality of extending portions are provided around each of the three parallel auxiliary electrodes 51 and have a size that is not connected to each other. At the end in the extending direction of the auxiliary electrode 51, radially extending portions are provided. As described above, the extending portion and the first region 54 can be provided in an arbitrary shape and size in a portion where the current density is large and the emission intensity is strong in the semiconductor layer 52, thereby suppressing current diffusion and light absorption suppression of the semiconductor layer. It is possible to adjust.

  In the fifth embodiment, the extending portion has a rectangular shape, but the length in the longitudinal direction of the extending portion is preferably 100 to 200 μm in top view. As a result, the extended portion is formed far from the first electrode 55 while securing the first region 54 with a thin semiconductor layer 52 as much as possible, so that the voltage rise is suppressed and the light emission efficiency is improved. . That is, if the area of the extended portion in the top view is increased, a semiconductor light emitting element with a lower voltage can be obtained.

<Sixth embodiment>
Next, a semiconductor light emitting element according to a sixth embodiment will be described. FIG. 9 is a schematic plan view showing the electrodes, the first region, and the second region of the semiconductor light emitting device according to the sixth embodiment. The semiconductor light emitting device 600 according to the sixth embodiment is similar to the fourth or fifth embodiment except that the shape and arrangement of the electrode 65 on the upper surface of the semiconductor layer 62, the second region 63, and the first region 64 are different. And substantially the same.

  In the semiconductor light emitting device 600 according to the sixth embodiment, the auxiliary electrode 61 extends from the plurality of pad electrodes 60 provided at the peripheral portion of the semiconductor layer 62 in the direction of the central region of the semiconductor layer 62. Each auxiliary electrode 61 is arranged so that the tip end faces in the central region in the adjacent direction. The extending portion composed of the second region 63 is provided around the pad electrode 60 and the auxiliary electrode 61. The extending portion that is substantially rectangular is arranged around the auxiliary electrode 61 such that the longitudinal direction of the rectangle is substantially perpendicular to the extending direction of the auxiliary electrode 61. Thus, even if the auxiliary electrode has a bent shape, the extended portion can be provided in the semiconductor layer 62 at a portion where the current density is large and the emission intensity is strong with an arbitrary shape, size, and angle. .

<Seventh embodiment>
Next, a semiconductor light emitting element according to a seventh embodiment will be described. FIG. 10 is a schematic plan view showing the electrodes, the first region, and the second region of the semiconductor light emitting device according to the seventh embodiment. The semiconductor light emitting device 700 according to the seventh embodiment is the same as the fourth to sixth embodiments except that the shape and arrangement of the electrode 75 on the upper surface of the semiconductor layer 72, the second region 73, and the first region 74 are different. It is substantially the same.

  In the semiconductor light emitting device 700 according to the seventh embodiment, the auxiliary electrode 71 extends in all directions from the plurality of pad electrodes 70 provided in the central region of the semiconductor layer 72. The extending portion including the second region 73 and the first region 74 are provided around the pad electrode 70 and the auxiliary electrode 71. The extending portion that is substantially rectangular is arranged around the auxiliary electrode 71 such that the longitudinal direction of the rectangle is substantially perpendicular to the extending direction of the auxiliary electrode 71. In addition, extending portions are provided radially at the ends of the extending portions of the pad electrode 70 and the auxiliary electrode 71. As described above, the extending portion has an arbitrary shape or a portion of the semiconductor layer 72 where the current density is large and the light emission intensity is strong even when the plurality of auxiliary electrodes 71 are radially extended from the pad electrode 70 or are extended in different directions. It can be provided with a size and an angle.

  Hereafter, the manufacturing method and each structure of this embodiment are explained in full detail.

(Semiconductor layer)
The semiconductor layer having the light emitting layer may be any semiconductor structure manufactured using a method and structure known in the art. A semiconductor structure having a second conductivity type semiconductor layer, a light emitting layer, and a first conductivity type semiconductor layer is formed on the growth substrate. The growth substrate may be any substrate that can epitaxially grow a nitride semiconductor that is a semiconductor layer, and the size and thickness of the growth substrate are not particularly limited. As this growth substrate, an insulating substrate such as sapphire or spinel (MgAl ₂ O ₄ ) whose main surface is any one of the C-plane, R-plane, and A-plane, silicon carbide (6H, 4H, 3C), Examples include silicon, ZnS, ZnO, Si, and GaAs. A nitride semiconductor substrate such as GaN or AlN can also be used.

  The semiconductor layer of the present invention is not limited to the above, and various light emitting structures such as a pn junction, a pin structure, and a MIS structure can be used. The present invention is not limited to nitride semiconductors but can be applied to other materials such as GaAs-based and InP-based materials such as InGaAs and GaP semiconductors and light-emitting elements having wavelengths.

On the growth substrate, an n-type nitride semiconductor layer, a light emitting layer, and a p-type nitride semiconductor layer are sequentially stacked as semiconductor layers. At this time, depending on the material of the growth substrate, a low-temperature growth buffer layer, for example, _{1 to 3} nm of Al _x Ga _1-x N (0 ≦ x ≦ 1), or other high-temperature growth layer, for example, between the semiconductor structure and the semiconductor structure. An under layer such as 0.5 to 4 μm of Al _x Ga _1-x N (0 ≦ x <1) may be interposed. The n-type and p-type nitride semiconductor layers are, for example, those represented by a composition formula of Al _x Ga _y In _1-xy N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, x + y ≦ 1). Some of the other group III and IV elements may be substituted with B substitution, P, As, Sb, etc., respectively. For example, a GaN contact layer and an InGaN / GaN multilayer structure are used for the n-type semiconductor layer, and a GaN contact layer, a single layer of AlGaN, InGaN, and GaN and a multilayer structure are used for the p-type semiconductor layer. can do. As described above, a single layer or a multilayer structure having various compositions and dopant amounts can be provided, and a layer of each function (contact, clad) can be provided. Each conductive type semiconductor layer is formed into a desired conductive type layer using an appropriate dopant. For example, in p-type and n-type nitride semiconductors, Mg, Si, or the like is used. A part of each conductivity type layer may have an insulating or semi-insulating region or layer, or a region or layer having a reverse conductivity type.

The light emitting layer used in the present invention includes, for example, _{a well} layer made of Al _a In _b Ga _1-ab N (0 ≦ a ≦ 1, 0 ≦ b ≦ 1, a + b ≦ 1), and Al _c In _d. A quantum well structure including a barrier layer made of Ga _1-c-d N (0 ≦ c ≦ 1, 0 ≦ d ≦ 1, c + d ≦ 1). The nitride semiconductor used for the active layer may be any of non-doped, n-type impurity doped, and p-type impurity doped. However, it is preferable to increase the light emitting element by using a non-doped or n-type impurity doped nitride semiconductor. Can be output. By including Al in the well layer, a wavelength shorter than the wavelength 365 nm which is the band gap energy of GaN can be obtained. The wavelength of light emitted from the active layer is approximately 360 to 650 nm, preferably 380 to 560 nm, depending on the purpose and application of the light-emitting element.

The composition of the well layer is preferably InGaN, and the composition of the barrier layer at that time is preferably GaN or InGaN. The thickness of the well layer is preferably 1 nm or more and 30 nm or less, and can be a multiple quantum well structure of a plurality of well layers through a single quantum well, a barrier layer, or the like of one well layer.

(Second electrode)
A second electrode made of Rh, Ag, Ni, Au, Ti, Al, Pt or the like is patterned on the surface of the second conductivity type semiconductor layer. Since the second electrode is on the light reflecting side, it is preferable to have a reflecting structure, specifically, to have a reflective layer with high reflectivity, particularly on the second conductive type semiconductor layer contact side. In addition, a multilayer structure in which, for example, an adhesive layer / a reflective layer are stacked in order through an adhesive layer of a light-transmitting thin film may be used. A specific second electrode can be Ag / Ni / Ti / Pt from the semiconductor layer side. In addition, it is preferable that the second electrode be formed in almost the entire region of the nitride semiconductor layer excluding the region where the first electrode is formed as viewed from above, because the light emitting region for current injection can be increased. Further, in plan view, if the first and second electrodes have a region overlapping with the light emitting layer interposed therebetween, the first electrode and the second electrode are absorbed into the electrode and cause optical loss, so that they should be shifted.

(Protective film)
A protective film may be provided to protect the periphery of the semiconductor light emitting element. When provided on the second conductivity type semiconductor layer, it is formed in a region exposed from the second electrode, and is provided adjacent to or spaced apart from each other. Not only this but it can also provide so that a part of 2nd electrode may be covered. Using this protective film as an insulating film, the second electrode selectively provided on the surface of the second conductivity type semiconductor layer is electrically connected to the semiconductor layer. As an insulating protective film, specific materials include a single layer film of an oxide film such as SiO ₂ , Nb ₂ O ₅ , Al ₂ O ₃ , ZrO ₂ , or TiO ₂ , or a nitride film such as AlN or SiN. Alternatively, a multilayer film can be used. Further, the protective film may be coated with a highly reflective metal film such as Al, Ag, and Rh. Furthermore, a part of the multilayer structure of the second electrode may be provided on the adhesive layer side of the insulating film, such as SiO ₂ / Ti / Pt.

(Semiconductor layer side adhesive layer)
Next, a semiconductor layer side adhesive layer for alloying at the time of bonding is formed on the second electrode. The semiconductor layer side adhesive layer is formed of an alloy containing at least one selected from the group consisting of Au, Sn, Pd, and In. The semiconductor layer side adhesive layer preferably has a three-layer structure including an adhesion layer, a barrier layer, and a eutectic layer. The adhesion layer contains at least one selected from the group consisting of Ni, Ti, RhO, W, and Mo. The barrier layer contains at least one selected from the group consisting of Pt, Ti, Pd, TiN, W, Mo, WN, and Au. The eutectic layer contains at least one selected from the group consisting of Au, Sn, Pd, and In. The film thickness of the semiconductor layer side adhesive layer is 5 μm or less. For example, Ti / Pt / Au / Sn / Au can be used. When a part of the multilayer structure of the second electrode is provided on the protective film, the adhesion layer is omitted and Pt / Au / Sn / Au is used. You can also.

(Support substrate)
On the other hand, a support substrate is prepared. The support substrate mainly includes a conductive substrate such as a Si substrate, a GaAs semiconductor substrate, a Cu, Ge, Ni metal material, or a Cu—W composite material. In addition, a composite of a metal and a ceramic such as Cu—Mo, AlSiC, AlN, SiC, and Cu—diamond can be used. For example, general formulas of Cu-W and Cu-Mo can be shown as Cu _x W _100-x (0 ≦ x ≦ 30) and Cu _x Mo _100-x (0 ≦ x ≦ 50), respectively. The advantage of using Si is that it is inexpensive and easy to chip. A preferable film thickness of the support substrate is 50 to 500 μm. Heat dissipation is improved by setting the film thickness of the support substrate within this range. On the other hand, if a conductive substrate is used as the support substrate, power can be supplied from the substrate side, and an element having high electrostatic withstand voltage and heat dissipation can be obtained. Moreover, it is usually an opaque material such as Si, Cu (Cu—W), and a structure in which a reflective structure is provided between the semiconductor layer and the semiconductor layer, for example, an electrode or a semiconductor layer. Excellent and preferable. Alternatively, a plating member can be formed on the nitride semiconductor layer by plating to form a support substrate and an adhesive portion between the support substrate. Further, an element without a support substrate may be used, and the element may be directly mounted on the mounting portion or base of the light emitting device, or a metal member or the like by plating may be provided on the semiconductor layer.

Also, a distributed Bragg reflection film on the reflection side of the semiconductor layer facing the light extraction side, for example, the upper surface or the lower surface of the support substrate, or the surface of the nitride semiconductor layer described above (here, the surface of the second conductivity type semiconductor layer). It is also possible to form a multilayer thin film in which materials having different refractive indexes, such as (Distributed Bragg reflector: DBR), are laminated alternately and periodically. The multilayer thin film is composed of, for example, a dielectric multilayer film or a semiconductor of GaN / AlGaN, and can be formed alone or together with a reflective electrode on the surface of the semiconductor layer, such as a protective film, to provide a reflective structure. .

(Lamination process)
Then, the surface of the semiconductor layer side adhesive layer and the surface of the support substrate side adhesive layer are opposed to each other, and the support substrate is bonded to the second electrode on the nitride semiconductor layer side by heating and pressure welding. This heating and pressure welding is performed by applying heat of 150 ° C. or higher while pressing. Thereby, the semiconductor layer side and the support substrate side are bonded via the adhesive layer.

  It is preferable to form a support substrate side adhesive layer also on the surface of this support substrate. Further, it is preferable to use a three-layer structure including an adhesion layer, a barrier layer, and a eutectic layer for the support substrate side adhesive layer. The support substrate side adhesive layer is, for example, Ti—Pt—Au, Ti—Pt—Sn, Ti—Pt—Pd or Ti—Pt—AuSn, W—Pt—Sn, RhO—Pt—Sn, RhO—Pt—Au, It is formed from a metal film such as RhO—Pt— (Au, Sn).

For eutectic bonding, it is preferable to provide an adhesion layer, a barrier layer, and a eutectic layer on the bonding surface between the support substrate side and the nitride semiconductor side, respectively, and materials (substrate, semiconductor) on which the layers are provided The adhesive layer and the material of each layer are formed as appropriate. After bonding, the second electrode / Ti-Pt-AuSn-Pt-Ti / support substrate, the second electrode / RhO-Pt-AuSn-Pt-Ti / support substrate, and the second electrode / Ti-Pt-PdSn- Pt—Ti / support substrate, second electrode / Ti—Pt—AuSn—Pt—RhO / support substrate, second electrode / Ti—Pt—Au—AuSn—Pt—TiSi ₂ / support substrate, Ti / Pt / AuSn / PdSn / Pt / TiSi ₂ / support substrate and Pt / AuSn / PdSn / Pt / TiSi ₂ / support substrate (when the protective film is SiO ₂ / Ti / Pt). Thus, when the surface metal of the bonding is different between the support substrate side and the nitride semiconductor element side, it is preferable because eutectic is possible at a low temperature and the melting point after eutectic is increased.

(Growth substrate removal process)
Thereafter, the growth substrate is removed to expose the semiconductor layer. The growth substrate is peeled and removed by irradiating an excimer laser, a femtosecond laser, or the like from the growth substrate side (Laser Lift Off: LLO), or removed by grinding. After removing the growth substrate, the exposed surface of the nitride semiconductor is subjected to a CMP (Chemical Mechanical Polish) process to expose the first conductive semiconductor layer which is a desired film. At this time, by removing the base layer having a high absorptance with respect to the light of the semiconductor light emitting element, for example, a GaN layer grown at a high temperature, or reducing the film thickness, for example, an LED having an emission wavelength in the ultraviolet region has an effect of absorption. Can be reduced. By this treatment, the damage layer can be removed, the thickness of the nitride semiconductor layer can be adjusted, and the surface roughness can be adjusted.

(Division of semiconductor layers)
Further, the semiconductor layer is divided into chips. Specifically, the outer peripheral etching is performed by RIE or the like, and the outer semiconductor layer is removed and separated to expose the protective film.

(Formation of first region and second region)
And the uneven structure which consists of a 1st area | region and a 2nd area | region is formed in a semiconductor layer upper surface. A resist mask having a predetermined pattern is formed on the upper surface of the first conductivity type semiconductor layer by photolithography. The first conductive semiconductor layer is RIE by 0.5 to 2 μm, preferably 0.5 to 1 μm, using a resist mask. At this time, the concavo-convex structure including the first region and the second region may be formed not only by RIE but also by wet etching or the like, and the concavo-convex structure is also formed in the first conductivity type semiconductor layer located immediately below the electrode. Also good.

  Furthermore, anisotropic etching is performed with a TMAH (tetramethylammonium hydroxide) solution on the first region and the second region on the upper surface of the first conductivity type semiconductor layer. By this treatment, the surfaces of the first region and the second region become rough, and the adhesion with the first electrode formed on the first conductivity type semiconductor layer and the light extraction efficiency are improved.

(First electrode)
Next, a first electrode is formed on the upper surface of the first conductivity type semiconductor layer so as to satisfy the arrangement configuration described above. In other words, the first electrode is arranged so as not to have an overlapping region with the formation region of the second electrode located across the light emitting layer in plan view from the upper surface of the semiconductor layer. With this structure, in the stacking direction of the semiconductor layer, carriers move three-dimensionally between both electrodes having different central axes, so that in-plane diffusion is promoted, resulting in an increase in internal quantum efficiency.

  Specifically, the first electrode is for the ohmic contact with the first conductivity type semiconductor layer and the Ti layer (first layer) for the pad and the pad, such as Ti—Au, Ti—Al, etc., in the order of lamination. As a pad layer (second layer) of gold, Al, platinum group, and a first layer for ohmic (for example, W, Mo, Ti are preferable for ohmic contact with the first conductivity type semiconductor layer), A structure in which a refractory metal layer (W, Mo, platinum group) is provided as a barrier layer between the second layer for pads, for example, W—Pt—Au, Ti—Rh—Pt—Au is used. Al or an alloy thereof can be used as the reflective electrode of the n-type nitride semiconductor, and a conductive oxide such as ITO can be used as the translucent electrode. In the embodiment, when an n-electrode is formed as the first electrode, Ti—Al—Ni—Au, W—Al—W—Pt—Au, Al—Pt—Au, Ti—Pt—Au, etc. are used in the order of lamination. It is done. The first electrode has a thickness of 0.1 to 1.5 μm.

(Chip division)
Subsequently, dicing is performed at a dicing position in a boundary region of the semiconductor light emitting element on a support base composed of a support substrate and an adhesive layer, thereby obtaining a semiconductor light emitting element in a chip form.

(Translucent conductive layer)
A diffusion layer that promotes current diffusion can also be provided between the semiconductor layers with each electrode. The diffusion layer is wider than each electrode, has a large area, has a diffusion function, and is translucent so that it can emit light (on the first electrode side) and reflect (on the second electrode side). What does not reduce is good, for example, a translucent conductive layer can be employed. The conductive layer is formed on almost the entire surface of the exposed semiconductor layer, whereby current can be spread uniformly over the entire semiconductor layer. Specifically, the translucent conductive layer is desirably formed of a translucent conductive layer containing an oxide of Zn, In, Sn, such as ITO, ZnO, In ₂ O ₃ , SnO ₂ , preferably ITO Is used. Alternatively, other metals such as Ni may be used as thin films, oxides, nitrides, compounds thereof, and composite materials.

(Wiring structure)
In the semiconductor light emitting device having the above structure, if the adhesive layer is conductive and the support substrate is a conductive substrate such as SiC, one main surface of the second electrode is brought into contact with the second conductive semiconductor layer. The second electrode can be externally connected from the other main surface side. That is, one main surface (upper surface) of the second electrode is a surface for contacting the semiconductor, and the other main surface (lower surface) of the second electrode can function as a surface for external connection. Then, the supporting substrate to be bonded is electrically connected to the second electrode, and the bottom surface side of the semiconductor light emitting element can be used as the pad portion of the second electrode. For example, an external circuit can be connected via an electrode provided on the back surface of the support substrate. In addition, when the support substrate is made of an insulating material, the support substrate electrode formed on the semiconductor laminated structure side and the electrode formed on the opposite side are connected to the support substrate by three-dimensional wiring or wiring via holes. Even if the wiring electrodes are connected with each other, the electrodes can be taken out from the back side of the support substrate. In any case, the second electrode and the external electrode can be electrically connected without using the exposed wire. Furthermore, a further heat dissipation effect can be obtained by connecting a separate heat dissipation member to the support substrate.

  On the other hand, the first electrode, which is an electrode on the surface side of the semiconductor layer, is connected to an exposed region for connecting an external power source with a conductive wire via solder or the like. Thereby, electrical connection with the external electrode becomes possible. In addition, a form having a wiring structure on the semiconductor layer, for example, a structure in which a wiring layer is provided from the semiconductor layer to an external support substrate may be used. In that case, the external connection of the support substrate, the wiring structure, etc. Connected. In such a light emitting element and device that does not use wire connection, a pad electrode wider than the auxiliary electrode becomes unnecessary, and the tendency of current concentration can be suppressed, and a phosphor layer described later and a sealing member including the phosphor layer are suitable. Can be formed.

  Further, in the semiconductor light emitting device, the supporting substrate is made of a material having good electrical conductivity, and thus a vertical electrode structure in which the upper and lower sides of the light emitting layer are sandwiched in three dimensions with electrodes can be used. The semiconductor layer can be diffused over the entire surface, and the in-plane spread of the current becomes uniform. That is, electrical resistance can be reduced and carrier injection efficiency is improved. Furthermore, the support substrate can also function as a heat dissipation substrate, and can suppress deterioration of element characteristics due to heat generation.

  Furthermore, the semiconductor light emitting device of the present invention can be sealed with a resin containing a light conversion member that converts a part of light from the semiconductor light emitting device into light of a different wavelength. The light conversion member is configured to include at least a fluorescent material that is excited by a light emission wavelength from the semiconductor light emitting element to emit fluorescent light, or includes a fluorescent material and a binder, and optionally an inorganic member (glass, filler, etc.). Is done. Thereby, the light of the semiconductor light emitting element is converted, and the light from the semiconductor light emitting element is mixed with the converted light and the fluorescent light, so that a light emitting device that emits desired light such as white color or light bulb color can be obtained. .

  The light conversion member contained in the sealing resin may be cured while being dispersed in the resin in the manufacturing process, but before the resin is cured, the semiconductor light emitting element is mounted by forced centrifugal force. It can also be deposited on the other side. As a result, the light conversion member can enter the groove formed by the first region and the second region on the upper surface of the semiconductor layer, and can be a densely packed layer of the light conversion member, which improves the efficiency of light conversion.

  The following semiconductor light emitting device was produced. The present invention is not limited to these examples.

<Example 1>
As Example 1, as shown in FIGS. 1-3, the semiconductor light-emitting device according to the first embodiment was produced with the following specifications.
The semiconductor light emitting device according to Example 1 includes a semiconductor layer 12 including a second conductive semiconductor layer (p-type semiconductor layer) 112, a light emitting layer 113, a first conductive semiconductor layer (n-type semiconductor layer) 111, a first At least an electrode (n electrode) 15, a second electrode (p electrode) 16, a protective film 107, a support substrate 104, and a support base 103 including an adhesive layer 105 are provided.
More specifically, the semiconductor layer 12 is a gallium nitride semiconductor, and the first electrode 15 is Ti.
(13 nm) / Pt (200 nm) / Au (1000 nm), and Ag (
100 nm) / Ni (100 nm) / Ti (100 nm) / Pt (100 nm), protective film 107 as SiO ₂ (400 nm), bonding layer 105 as Au (500 nm) / Pt (200 nm) / TiSi ₂ (3 nm), support substrate A Si substrate was used as 104.
Further, a pattern of the first and second regions was formed in the first conductive type semiconductor layer (n-type semiconductor layer) with a thickness difference of 1 μm between the first and second regions to obtain a semiconductor light emitting device (a).
The size of the semiconductor light emitting element (a) was 2 mm square, the diameter of the n-type pad electrode was 100 μm, and the width of the n-type auxiliary electrode was 20 μm. The stripe widths of the first and second regions were each 20 μm.

<Reference example>
As a reference example, in the same manner as in Example 1 except that the n-electrode pattern of FIG. 1 is used and the first region is formed in the first conductive semiconductor layer (n-type semiconductor layer) other than the n-electrode forming portion. A semiconductor light emitting device (b) was produced.

<Comparative example>
As a comparative example, a semiconductor light emitting device (Ref) was manufactured in the same manner as in the example except that the n electrode pattern of FIG. 1 was used and the first region was not formed.

  The evaluation was performed using the semiconductor light emitting elements (a), (b), and (Ref). 11A shows a top view photograph of the semiconductor light emitting device of Example 1 and FIG. 11B shows the reference example.

  FIG. 12 shows the emission intensity distribution, and shows the results of comparison in absolute values of Example 1 (a), Reference Example (b), and Comparative Example (Ref) when the input current is 350 mA in each semiconductor light emitting device. Yes. FIG. 13 is a graph comparing the light output (Po) and the forward voltage (Vf) when the input current is 350 mA in each semiconductor light emitting device.

  As is clear from the emission intensity distribution of FIG. 12, it was confirmed that the periphery of the electrode formation portion of Example 1 (a) emitted light more strongly than the reference example (b) and the comparative example (Ref). Further, from the result of FIG. 13, the light output of the semiconductor light emitting devices (a) and (b) in which the first region is formed on the upper surface of the n-type semiconductor layer is improved as compared with the comparative example (Ref). In addition to forming only the first region in the n-type semiconductor layer other than the n-electrode forming portion, in addition to the first region, it is preferable to have the second region that is exposed and extended from the n-electrode, that is, the extension portion. In addition to the improvement in light output, the forward voltage also decreased. Thereby, the predominance of the pattern of the 1st, 2nd area | region of Example 1 (a) was confirmed.

The semiconductor light emitting device of the present invention can be suitably used for illumination light sources, LED displays, backlight light sources, traffic lights, illumination switches, various sensors, various indicators, and the like.

10, 20, 30, 40, 50, 60, 70 Pad electrodes 11, 21, 31, 41, 51, 61, 71 Auxiliary electrodes 12, 22, 32, 42, 52, 62, 72 Semiconductor layers 13, 23, 33 , 43, 53, 63, 73 Second region 14, 24, 34, 44, 54, 64, 74 First region 15, 25, 35, 45, 55, 65, 75 First electrode 16 Second electrode 100, 200 , 300, 400, 500, 600, 700 Semiconductor light emitting device 103 Support base 104 Support substrate 105 Adhesive layer 107 Protective film 111 First conductive type semiconductor layer 112 Second conductive type semiconductor layer 113 Light emitting layer

Claims (6)

A semiconductor light emitting device comprising: a semiconductor layer; a first electrode disposed on an upper surface of the semiconductor layer; and a second electrode disposed on a lower surface of the semiconductor layer,
The upper surface of the semiconductor layer has a first region and a second region in which the semiconductor layer is thicker than the first region,
The first electrode includes a pad electrode and an auxiliary electrode extending from the pad electrode,
The first electrode is on the second region;
The second region includes a semiconductor light emitting element having a portion along the auxiliary electrode and a portion extending in a direction different from the auxiliary electrode.   The semiconductor light emitting device according to claim 1, wherein there are a plurality of the second regions and are connected to each other.   3. The semiconductor light emitting element according to claim 1, wherein the one extending in a direction different from the auxiliary electrode is perpendicular to the one along the auxiliary electrode.   4. The semiconductor light emitting element according to claim 1, wherein a plurality of the second regions are arranged in a stripe shape. 5.   The semiconductor light emitting element according to claim 1, wherein an upper surface of the semiconductor layer is a rough surface. The semiconductor layer has p-type and n-type nitride semiconductor layers,
6. The semiconductor light emitting element according to claim 1, wherein the second region is provided on the n-type nitride semiconductor layer.