JP2010062355A - Light-emitting device - Google Patents

Abstract

A light-emitting element with excellent long-term reliability is provided.
A light emitting device according to the present invention includes a first conductive type first semiconductor layer, a second conductive type second semiconductor layer different from the first conductive type, a first semiconductor layer, and a second semiconductor. A semiconductor stacked structure 10 having an active layer 105 sandwiched between layers, and a first electrode that is provided on the opposite side of the first semiconductor layer that is in contact with the active layer 105 and that supplies current to the first semiconductor layer; And a second electrode that is provided at a position away from the first electrode and supplies a current to the first semiconductor layer, and the active layer 105 has a current supplied to both the first electrode and the second electrode. Light is emitted when the supplied current spreads in the horizontal direction of the active layer 105.
[Selection] Figure 1A

Description

  The present invention relates to a light emitting element. In particular, the present invention relates to a light emitting element having a large planar size.

  Conventionally, a silicon substrate having an anode electrode, a metal reflection film layer connected to the silicon substrate via a bonding metal layer, and a semiconductor region bonded to the metal reflection film via a conductive light transmission film are provided. A light-emitting element having a semiconductor region having an n-type semiconductor layer, a p-type semiconductor layer, and an active layer sandwiched between the n-type semiconductor layer and the p-type semiconductor layer is known (for example, patents). Reference 1).

  The light emitting element described in Patent Document 1 includes a light transmission film having conductivity between a semiconductor region and a metal reflection layer, and the light transmission film is in ohmic contact with both the semiconductor region and the metal light reflection film. Since alloying between the semiconductor region and the metal light reflecting film is suppressed, an excellent light reflecting surface can be configured.

JP 2005-175462 A

  However, in the light-emitting element described in Patent Document 1, when a large current is supplied to the semiconductor region through the electrode, current may concentrate on a part of the active layer, and the light-emitting element emits light after long-term use. There may be a problem that disappears.

  Accordingly, an object of the present invention is to provide a light-emitting element having excellent long-term reliability.

  In order to achieve the above object, the present invention provides a first semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type different from the first conductivity type, a first semiconductor layer, a second semiconductor layer, A semiconductor stacked structure having an active layer sandwiched between and a first electrode that is provided on the opposite side of the first semiconductor layer that is in contact with the active layer, and that supplies current to the first semiconductor layer, and a first electrode A second electrode for supplying a current to the first semiconductor layer, and the active layer is activated when the current is supplied to both the first electrode and the second electrode. A light-emitting element that emits light by spreading in the horizontal direction of the layer is provided.

  In the light emitting device, the active layer is either the first electrode supplied with current or the second electrode supplied with current when current is supplied to either the first electrode or the second electrode. It is preferable to prevent light emission due to the concentration of the current supplied to a part of the active layer immediately below.

  In the light emitting device, the first electrode includes a first circular electrode and a first linear electrode electrically connected to the first circular electrode, the second electrode includes a second circular electrode, A second linear electrode that is electrically connected to the two-circular electrode, and the first linear electrode may not be electrically connected to the second linear electrode.

  In the light emitting device, the first electrode has a first circular electrode, a first linear electrode electrically connected to the first circular electrode, and a first cross-sectional area smaller than a cross-sectional area of the first linear electrode. The second electrode has a cross-sectional area smaller than the cross-sectional area of the second circular electrode, the second linear electrode electrically connected to the second circular electrode, and the second linear electrode, And a second connection electrode electrically connected to the first connection electrode.

  The light emitting device further includes a support substrate having a reflective portion, and the semiconductor multilayer structure is supported on the support substrate via a transparent layer including a contact portion that electrically connects the semiconductor multilayer structure and the reflective portion. Also good.

  The light emitting device according to the present invention can provide a light emitting device having excellent long-term reliability.

[First Embodiment]
FIG. 1A is a schematic longitudinal sectional view of a light emitting device according to a first embodiment of the present invention. 1B shows a schematic top view of the light emitting device according to the first embodiment of the present invention, and FIG. 1B (b) shows a line AA in FIG. 1A. The typical top view of the light emitting element at the time of cut | disconnecting a light emitting element is shown. 1A is a cross-sectional view taken along line BB in FIG. 1B (a).

(Outline of structure of light-emitting element 1)
The light emitting element 1 according to the first embodiment is electrically connected to a semiconductor multilayer structure 10 having an active layer 105 that emits light of a predetermined wavelength and a partial region on one surface of the semiconductor multilayer structure 10. A first surface electrode 110 as a first electrode, a second surface electrode 112 as a second electrode, and a pad electrode 115 as a wire bonding pad provided on each surface of the first surface electrode 110 and the second surface electrode 112. A contact part 120 electrically connected to a part of the other surface of the semiconductor multilayer structure 10, and a transparent layer 140 covering the other surface of the semiconductor multilayer structure 10 excluding a region where the contact part 120 is provided, And a reflective portion 130 provided on the surface of the contact portion 120 and the transparent layer 140 on the opposite side of the surface in contact with the semiconductor multilayer structure 10.

  Furthermore, the light-emitting element 1 includes an adhesion layer 200 having electrical conductivity provided on the opposite side of the surface in contact with the contact portion 120 and the transparent layer 140 of the reflection portion 130 and the opposite side of the surface of the adhesion layer 200 in contact with the reflection portion 130. The support substrate 20 having electrical conductivity provided on the back surface, and a back electrode 210 provided on the surface of the support substrate 20 opposite to the surface in contact with the adhesion layer 200 are provided.

  In addition, the semiconductor multilayer structure 10 of the light-emitting element 1 according to this embodiment includes a p-type contact layer 109 provided in contact with the contact portion 120 and the transparent layer 140, and a surface in contact with the transparent layer 140 of the p-type contact layer 109. A p-type cladding layer 107 as a second conductivity type second semiconductor layer provided on the opposite side of the active layer 105, and an active layer 105 provided on the opposite side of the surface of the p-type cladding layer 107 in contact with the p-type contact layer 109; The n-type cladding layer 103 as the first conductivity type first semiconductor layer provided on the opposite side of the surface of the active layer 105 in contact with the p-type cladding layer 107 and the active layer 105 of the n-type cladding layer 103 are in contact with each other. And an n-type contact layer 101 provided in a partial region on the opposite side of the surface.

  The surface of the semiconductor multilayer structure 10 opposite to the side in contact with the transparent layer 140 is a light extraction surface of the light emitting element 1 according to this embodiment. Specifically, a part of the surface opposite to the surface in contact with the active layer 105 of the n-type cladding layer 103 becomes the light extraction surface. Then, on the light extraction surface of the n-type clad layer 103, a concavo-convex shape portion 103a is formed in which concavo-convex portions having one concave portion and one convex portion as one pair are continuously connected. For example, one concave portion and another concave portion, or one convex portion and another convex portion are formed on the surface of the n-type cladding layer 103 at a predetermined interval, whereby the surface of the n-type cladding layer 103 is formed. An uneven shape portion 103a is provided.

  Further, the reflective portion 130 is provided in contact with the reflective layer 132 on the opposite side of the reflective layer 132 provided in contact with the contact portion 120 and the transparent layer 140 and the surface of the reflective layer 132 in contact with the contact portion 120 and the transparent layer 140. The barrier layer 134 includes a bonding layer 136 provided in contact with the barrier layer 134 on the side opposite to the surface of the barrier layer 134 in contact with the reflective layer 132. The adhesion layer 200 includes a bonding layer 202 that mechanically and electrically bonds to the bonding layer 136 of the reflective portion 130, and a barrier layer 204 that is provided on the opposite side of the surface of the bonding layer 202 that contacts the reflective portion 130. And a contact electrode 206 provided on the opposite side of the surface in contact with the bonding layer 202 of the barrier layer 204.

  Here, the light emitting element 1 has a side surface 10 a as an etching side surface including the side surface of the active layer 105. Specifically, the light emitting element 1 has a side surface 10 a including a side surface of the n-type cladding layer 103, a side surface of the active layer 105, a side surface of the p-type cladding layer 107, and a side surface of the p-type contact layer 109. The side surface 10 a is formed substantially perpendicular to the surface of the support substrate 20. Furthermore, the light emitting element 1 has a side surface 10b as a processed side surface including the side surface of the reflecting portion 130, the side surface of the adhesion layer 200, and the side surface of the support substrate 20.

  In the side surface 10a, part of the n-type cladding layer 103, part of the active layer 105, part of the p-type cladding layer 107, and part of the p-type contact layer 109 are removed by wet etching or the like. It is a surface that has occurred. On the other hand, the side surface 10b is a surface generated by mechanically cutting a part of the reflecting portion 130, a part of the adhesion layer 200, and a part of the support substrate 20 by dicing using a dicing apparatus or the like. It is. Therefore, the side surface 10a has a smooth surface compared to the side surface 10b.

  Moreover, as shown to Fig.1B (a), the light emitting element 1 which concerns on this embodiment is formed in a substantially square shape in top view. As an example, the vertical dimension and the horizontal dimension of the light emitting element 1 are each 1 mm. The thickness of the light emitting element 1 is formed to about 200 μm. That is, the light-emitting element 1 according to the present embodiment is a light-emitting element having a large chip size with a planar dimension of 500 μm or more, for example.

(Semiconductor laminated structure 10)
The semiconductor multilayer structure 10 according to this embodiment is formed by including an AlGaInP-based compound semiconductor that is a III-V group compound semiconductor. Specifically, the semiconductor stacked structure 10 includes an active layer 105 formed from a bulk of an undoped AlGaInP-based compound semiconductor that is not doped with an impurity dopant, and an n-type cladding formed by containing n-type AlGaInP. The structure is sandwiched between the layer 103 and the p-type cladding layer 107 formed to include p-type AlGaInP.

  The active layer 105 emits light of a predetermined wavelength when a current is supplied from the outside. For example, the active layer 105 is formed of a semiconductor material that emits red light having a wavelength of around 630 nm. In this embodiment, when a current is supplied to both the first surface electrode 110 and the second surface electrode 112, the supplied current spreads in the horizontal direction with respect to the active layer 105. In the present embodiment, the first surface electrode 110 and the second surface electrode 112 are provided at positions separated from each other when the light emitting element 1 is viewed from above. As a result, current does not concentrate on a part of the active layer 105, but the current spreads over substantially the entire active layer 105, and light is emitted from the active layer 105. On the other hand, when a current is supplied to either the first surface electrode 110 or the second surface electrode 112, the supplied current is concentrated in a region of the active layer 105 immediately below the surface electrode to which the current is supplied. . As a result, the current density in a part of the active layer 105 where the current is concentrated increases, so that the active layer temperature of the active layer 105 in the part increases. Then, as the active layer temperature of the active layer 105 increases, the active layer 105 in the region corresponding directly below the surface electrode loses the function of emitting light, and light is not emitted from the active layer 105 in this region.

The active layer 105 is, for example, be formed from an undoped _{(Al 0.1 Ga 0.9) 0.5 In} 0.5 P layer. The n-type cladding layer 103 includes an n-type dopant such as Si or Se at a predetermined concentration. As an example, the n-type cladding layer 103 is formed of an n-type (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P layer doped with Si. Furthermore, the p-type cladding layer 107 contains a p-type dopant such as Zn or Mg at a predetermined concentration. As an example, the p-type cladding layer 107 is formed of a p-type (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P layer doped with Mg.

  Furthermore, the p-type contact layer 109 included in the semiconductor multilayer structure 10 is formed of, for example, a p-type GaP layer doped with Mg at a predetermined concentration. The n-type contact layer 101 is formed from a GaAs layer doped with Si at a predetermined concentration. Here, the n-type contact layer 101 is provided in a region where the first surface electrode 110 and the second surface electrode 112 are provided on the upper surface of the n-type cladding layer 103.

(First surface electrode 110 and second surface electrode 120)
As shown in FIG. 1B (a), the first surface electrode 110 includes a circular electrode 110a formed in a substantially circular shape above the n-type cladding layer 103 and a plurality of electrodes electrically connected to the circular electrode 110a. The first linear electrode 110b is formed. In FIG. 1B (a), the pad electrode 115 is not shown for convenience of explanation.

  Specifically, in the first surface electrode 110, linear first linear electrodes 110 b substantially parallel to one side of the light emitting element 1 are arranged in parallel at a substantially constant interval. A circular electrode 110 a is arranged between one first linear electrode 110 b on the side and the other first linear electrode 110 b on the center side of the light emitting element 1. Further, the first linear electrode 110b located between one first linear electrode 110b and the other first linear electrode 110b is disposed at a position penetrating the vicinity of the center of the circular electrode 110a. The plurality of first linear electrodes 110b and the circular electrodes 110a are electrically connected by linear electrodes substantially perpendicular to the plurality of first linear electrodes 110b.

  The second surface electrode 120 is also formed in the same manner as the first surface electrode 110. That is, in the second surface electrode 120, linear second linear electrodes 112 b that are substantially parallel to one side of the light emitting element 1 are arranged in parallel at a substantially constant interval, and one side of the light emitting element 1 is arranged. A circular electrode 112 a is disposed between one second linear electrode 112 b and the other second linear electrode 112 b on the center side of the light emitting element 1. In addition, the second linear electrode 112b positioned between one second linear electrode 112b and the other second linear electrode 112b is disposed at a position penetrating the vicinity of the center of the circular electrode 112a. The plurality of second linear electrodes 112b and the circular electrode 112a are electrically connected to each other by the linear electrodes substantially perpendicular to the plurality of second linear electrodes 112b. Further, in the present embodiment, the first surface electrode 110 and the second surface electrode 112 are not electrically connected.

  In the present embodiment, the first surface electrode 110 and the second surface electrode 112 are provided apart from each other and are provided on substantially the same plane. That is, the first surface electrode 110 and the second surface electrode 112 are each provided on the surface of the same compound semiconductor layer (for example, the n-type contact layer 101). The n-type contact layer 101 is provided at a position sandwiched between the n-type cladding layer 103 immediately below the first surface electrode 110 and the second surface electrode 112 and the first surface electrode 110 and the second surface electrode 112. . As an example, the circular electrode 110a and the circular electrode 110b are formed in a circular shape with a diameter of 100 μm, and the plurality of first linear electrodes 110b and the plurality of second linear electrodes 112b are linear with a width of 10 μm. It is formed. Then, the width of the linear electrode that electrically connects the linear electrodes (the first linear electrode 110b and the second linear electrode 112b) on one side of the light emitting element 1 and the circular electrode, and the circular electrode and light emission. The width of the linear electrode that electrically connects the linear electrodes (the first linear electrode 110b and the second linear electrode 112b) on the center side of the element 1 is also formed with a width of 10 μm.

(Contact part 120)
The contact portion 120 is provided on the surface of the p-type contact layer 109 excluding a region corresponding to a region immediately below the first surface electrode 110 and the second surface electrode 112. As an example, the contact part 120 is formed from a metal material containing Au and Zn. In the present embodiment, as shown in FIG. 1B (b), the contact portion 120 includes a plurality of branch contact portions 120a and a rectangular contact portion having an opening on the inner side and extending along the outer periphery of the light emitting element 1. It consists of. The plurality of branch-like contact portions 120a are arranged at positions that do not overlap with the first linear electrodes 110b and the second linear electrodes 112b as viewed from above.

(Transparent layer 140)
The transparent layer 140 as a transparent layer is provided on the surface of the p-type contact layer 109 where the contact portion 120 is not provided. The transparent layer 140 is formed of a material that transmits the wavelength of light emitted from the active layer 105, and is formed of a transparent dielectric layer such as SiO ₂ , TiO ₂ , or SiN _x as an example. The transparent layer 140 has a wavelength of light emitted from the active layer 105 of λ, and the refractive index of the material constituting the transparent layer 140 is n (2 × λ) / (4 × n) or more. The thickness is formed. The transparent layer 140 can also be formed from a transparent conductor layer containing a metal oxide material such as ITO (Indium Tin Oxide) having a conductivity lower than that of the contact portion 120.

Moreover, the transparent layer 140 can also be formed from the laminated structure of the thin film which consists of a several material from which each refractive index differs. That is, the transparent layer 140 can have a distributed black reflector (DBR) structure. For example, the transparent layer 140 having a DBR structure in which a pair layer in which a layer made of SiO ₂ having a predetermined thickness and a layer made of TiO ₂ having a predetermined thickness are paired can be formed.

(Reflecting part 130)
The reflective layer 132 of the reflective unit 130 is formed of a conductive material having a predetermined reflectance with respect to light emitted from the active layer 105. As an example, the reflective layer 132 is formed of a conductive material having a reflectance of 80% or more with respect to the light. The reflection layer 132 reflects the light reaching the reflection layer 132 out of the light emitted from the active layer 105 toward the active layer 105 side. The reflective layer 132 is formed of, for example, a metal material such as Al, Au, or Ag, or an alloy containing at least one metal material selected from these metal materials. As an example, the reflective layer 132 is made of Al having a predetermined thickness. The barrier layer 134 of the reflection unit 130 is formed of a metal material such as Ti or Pt, and as an example, is formed of Ti having a predetermined thickness. The barrier layer 134 suppresses propagation of the material forming the bonding layer 136 to the reflective layer 132. The bonding layer 136 is formed of a material that is electrically and mechanically bonded to the bonding layer 202 of the adhesion layer 200, and is formed of Au having a predetermined thickness as an example.

(Supporting substrate 20)
The support substrate 20 is formed from a conductive material. The support substrate 20 can be formed of a p-type or n-type conductive Si substrate, a Ge substrate, a GaAs substrate, a GaP substrate, or a metal substrate made of a metal material such as Cu. For example, in this embodiment, a conductive Si substrate can be used as the support substrate 20.

  Then, the bonding layer 202 of the adhesion layer 200 can be formed of Au having a predetermined film thickness, similarly to the bonding layer 136 of the reflecting portion 130. The barrier layer 204 is formed of a metal material such as Ti or Pt, and can be formed of Pt having a predetermined thickness as an example. The barrier layer 204 prevents the material constituting the bonding layer 202 from propagating to the contact electrode 206. Further, the contact electrode 206 is formed from a material that is electrically bonded to the support substrate 20 and is formed from a metal material including Au, Ti, Al, or the like. As an example, the contact electrode 206 is formed of Ti having a predetermined film thickness.

  The back electrode 210 is formed from a material that is electrically bonded to the support substrate 20, and is formed from a metal material such as Ti or Au, for example. In the present embodiment, the back electrode 210 has Ti and Au. Then, Ti having a predetermined thickness is provided by being electrically bonded to the support substrate 20, and Au having a predetermined thickness is further provided on the Ti. The light-emitting element 1 is a predetermined stem of a stem formed of a metal such as Cu using a conductive bonding material such as Ag paste or a eutectic material such as AuSn with the back electrode 210 facing down. Mounted in position.

(Modification)
The light emitting element 1 according to the present embodiment emits light including red having a wavelength of 630 nm, but the wavelength of light emitted from the light emitting element 1 is not limited to this wavelength. The light emitting element 1 that emits light in a predetermined wavelength range can also be formed by controlling the structure of the active layer 105 of the semiconductor multilayer structure 10. Examples of light emitted from the active layer 105 include light in a wavelength range such as orange light, yellow light, or green light. The semiconductor multilayer structure 10 included in the light emitting element 1 can also be formed of an InAlGaN-based compound semiconductor including an active layer 105 that emits light in the ultraviolet region, the violet region, or the blue region.

  Furthermore, in the semiconductor multilayer structure 10 included in the light emitting element 1, the conductivity type of the compound semiconductor layer constituting the semiconductor multilayer structure 10 can be made opposite to that of the first embodiment. For example, the conductivity type of the n-type contact layer 101 and the n-type cladding layer 103 can be p-type, and the conductivity type of the p-type cladding layer 107 and the p-type contact layer 109 can be n-type. The uneven portion 103 a can also be provided on the surface of the n-type cladding layer 103 by forming uneven portions having no regularity on the surface of the n-type cladding layer 103.

  In addition, the contact portion 120 is formed in a single shape without a cut portion. However, in a modified example, the contact portion 120 formed of a plurality of regions is formed by forming a cut portion in a part of the contact portion 120. It can also be formed. For example, the contact part 120 can be formed in a plurality of dots.

  Moreover, the planar dimension of the light emitting element 1 is not restricted to said embodiment. For example, the planar dimension of the light-emitting element 1 can be designed such that the vertical dimension and the horizontal dimension are approximately 500 μm or more, or a dimension exceeding 1 mm, respectively. The light emitting element 1 can also be formed by appropriately changing the vertical dimension and the horizontal dimension. As an example, the planar dimension of the light emitting element 1 can be designed such that the vertical dimension is shorter than the horizontal dimension. In this case, the shape of the light emitting element 1 in a top view is substantially rectangular.

  The active layer 105 can also be formed with a quantum well structure. The quantum well structure can be formed from any structure of a single quantum well structure, a multiple quantum well structure, or a strained multiple quantum well structure.

(Method for Manufacturing Light-Emitting Element 1)
2A to 2J show the flow of the manufacturing process of the light emitting device according to the first embodiment of the present invention.

First, as shown in FIG. 2A (a), an AlGaInP-based material including a plurality of compound semiconductor layers on an n-type GaAs substrate 100 by, for example, metal organic vapor phase epitaxy (MOVPE method). A semiconductor multilayer structure 11 is formed. Specifically, on the n-type GaAs substrate 100, an etching stop layer 102 having undoped (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P, and an n-type doped with Si N-type contact layer 101 having GaAs, n-type cladding layer 103 having n-type (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P doped with Si, and undoped (Al _{0 .1} Ga _0.9 ) _0.5 In _0.5 P active layer 105 and Mg-doped p-type (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P A p-type cladding layer 107 and a p-type contact layer 109 containing p-type GaP doped with Mg are formed in this order using the MOVPE method. As a result, an epitaxial wafer in which the semiconductor multilayer structure 11 is formed on the n-type GaAs substrate 100 is formed.

Here, the formation of the semiconductor multilayer structure 11 using the MOVPE method is performed at a growth temperature of 650 ° C., a growth pressure of 6666.1 Pa (50 Torr), and a growth rate of each of the plurality of compound semiconductor layers included in the semiconductor multilayer structure 11. Is set from 0.3 nm / sec to 1.0 nm / sec, and the V / III ratio is set to about 200. The V / III ratio is a group V such as arsine (AsH ₃ ) and phosphine (PH ₃ ) based on the number of moles of a group III raw material such as trimethylgallium (TMGa) or trimethylaluminum (TMAl). It is the ratio of the number of moles of raw materials.

The raw materials used in the MOVPE method are organometallic compounds such as trimethylgallium (TMGa), triethylgallium (TEGa), trimethylaluminum (TMAl), trimethylindium (TMIn), arsine (AsH ₃ ), and phosphine (PH ₃ ). A hydride gas such as can be used. Furthermore, disilane (Si ₂ H ₆ ) can be used as a raw material for the n-type dopant. Then, the raw material of p-type dopant can be used biscyclopentadienyl magnesium (Cp 2 _Mg).

Alternatively, hydrogen selenide (H ₂ Se), monosilane (SiH ₄ ), diethyl tellurium (DETe), or dimethyl tellurium (DMTe) can be used as a raw material for the n-type dopant. And dimethyl zinc (DMZn) or diethyl zinc (DEZn) can also be used as a raw material of a p-type dopant.

  The semiconductor multilayer structure 11 on the n-type GaAs substrate 100 can also be formed using molecular beam epitaxy (MBE), halide vapor phase epitaxy (HALide Vapor Phase Epitaxy: HVPE), or the like. .

Next, as shown in FIG. 2A (b), after the epitaxial wafer formed in FIG. 2A (a) is unloaded from the MOVPE apparatus, a transparent layer 140 is formed on the surface of the p-type contact layer 109. Specifically, a SiO ₂ film as the transparent layer 140 is formed on the surface of the p-type contact layer 109 using a plasma CVD (Chemical Vapor Deposition) apparatus. In addition, when forming the transparent layer 140 from a several layer, it can form by a vacuum evaporation method.

  Next, as shown in FIG. 2B (c), an opening 140a is formed in the transparent layer 140 by using a photolithography method and an etching method. For example, a photoresist pattern having a groove in a region where the opening 140 a is to be formed is formed on the transparent layer 140. The opening 140 a is formed to penetrate from the surface of the transparent layer 140 to the interface between the p-type contact layer 109 and the transparent layer 140. Specifically, the opening 140a is formed in the transparent layer 140 using an etchant as a hydrofluoric acid-based etching solution.

  Subsequently, as shown in FIG. 2B (d), an AuZn alloy, which is a material for forming the contact portion 120, is formed in the opening 140a by using a vacuum deposition method. For example, the contact portion 120 is formed by vacuum-depositing AuZn in the opening 140a using a photoresist pattern used for forming the opening 140a as a mask. Next, as shown in FIG. 2B (e), an Al layer as the reflective layer 132, a Ti layer as the barrier layer 134, and an Au layer as the bonding layer 136 are formed by vacuum deposition. Thereby, the semiconductor laminated structure 1a is formed.

  2C (f), Ti as the contact electrode 206, Pt as the barrier layer 204, and Au as the bonding layer 202 are formed on a conductive Si substrate as the support substrate 20. It forms in order using a vacuum evaporation method. Thereby, the support structure 20a is formed. Subsequently, the bonding surface 136a, which is the surface of the bonding layer 136 of the semiconductor multilayer structure 1a, and the bonding surface 202a, which is the surface of the bonding layer 202 of the support structure 20a, are overlapped with each other, and this state is formed from carbon or the like. Hold with a jig to be done.

Subsequently, a jig holding the state in which the semiconductor multilayer structure 1a and the support structure 20a are overlapped is introduced into the wafer bonding apparatus. And the inside of a wafer bonding apparatus is made into a predetermined pressure. As an example, the pressure is set to 1.333 Pa (0.01 Torr). Then, pressure is applied to the semiconductor laminated structure 1a and the support structure 20a that are overlapped with each other via a jig. As an example, a pressure of 30 kgf / cm ² is applied. Next, the jig is heated to a predetermined temperature at a predetermined temperature increase rate.

  Specifically, the temperature of the jig is heated to 350 ° C. And after the temperature of a jig reaches about 350 degreeC, a jig is hold | maintained at the said temperature for about 30 minutes. Thereafter, the jig is slowly cooled. The temperature of the jig is sufficiently lowered to, for example, room temperature. After the temperature of the jig has dropped, the pressure applied to the jig is released. And the pressure in a wafer bonding apparatus is made into atmospheric pressure, and a jig is taken out. As a result, as shown in FIG. 2C (g), a bonded structure 1b is formed in which the semiconductor multilayer structure 1a and the support structure 20a are mechanically and electrically bonded between the bonding layer 136 and the bonding layer 202. Is done.

  In the present embodiment, the semiconductor multilayer structure 1 a includes the barrier layer 134. Therefore, even when the semiconductor multilayer structure 1a and the support structure 20a are bonded to each other at the bonding surface 136a and the bonding surface 202a, the material forming the bonding layer 136 and the bonding layer 202 diffuses into the reflective layer 132. This can be prevented and deterioration of the reflection characteristics of the reflective layer 132 can be suppressed.

  Next, the bonding structure 1b is affixed to the jig of the polishing apparatus with affixing wax. Specifically, the support substrate 20 side is attached to the jig. Then, the n-type GaAs substrate 100 of the bonded structure 1b is polished until it reaches a predetermined thickness. Subsequently, the polished bonded structure 1b is removed from the polishing plate, and the wax adhering to the surface of the support substrate 20 is washed away. Then, as shown in FIG. 2D (h), using the etchant for GaAs etching, the n-type GaAs substrate 100 is selectively and completely removed from the bonded structure 1b after polishing to expose the etching stop layer 102. The joined structure 1c is formed. As an etchant for GaAs etching, for example, a mixed solution of ammonia water and hydrogen peroxide water can be used. It is also possible to remove all n-type GaAs substrate 100 by etching without polishing n-type GaAs substrate 100.

  Then, as shown in FIG. 2D (i), the etching stop layer 102 is removed from the bonded structure 1c by etching using a predetermined etchant. Thereby, the bonded structure 1d from which the etching stop layer 102 has been removed is formed. As the predetermined etchant, an etchant containing hydrochloric acid can be used. As a result, the surface of the n-type contact layer 101 is exposed to the outside.

  Subsequently, the first surface electrode 110 and the second surface electrode 112 are formed at predetermined positions on the surface of the n-type contact layer 101 by using a photolithography method and a vacuum evaporation method. Each of the first surface electrode 110 and the second surface electrode 112 is formed of a circular electrode having a diameter of 100 μm and a plurality of linear electrodes having a width of 10 μm. The first surface electrode 110 and the second surface electrode 112 are respectively formed of AuGe, Ti, and Au on the n-type contact layer 101 in this order. In this case, each of the first surface electrode 110 and the second surface electrode 112 is formed so as not to be positioned immediately above the contact portion 120. Thereby, as shown to FIG. 2E, the joining structure 1e which has the 1st surface electrode 110 and the 2nd surface electrode 112 is formed.

Next, as shown in FIG. 2F, the n-type contact layer corresponding to the region immediately below the first surface electrode 110 and the second surface electrode 112 using the first surface electrode 110 and the second surface electrode 112 formed in FIG. 2E as a mask. The n-type contact layer 101 except for 101 is removed by etching using a mixed solution of sulfuric acid, hydrogen peroxide solution, and water. Thereby, the joined structure 1f is formed. By using the mixed solution, the n-type contact layer 101 formed of GaAs is changed to an n-type clad formed of n-type (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P. The layer 103 can be selectively etched. Therefore, in the bonded structure 1f, the n-type cladding layer 103 is exposed to the outside.

  Next, as shown in FIG. 2G, an uneven portion 103 a is formed on a part of the surface of the n-type cladding layer 103. Specifically, a mask pattern in which a concave pattern or a convex pattern is repeated at a predetermined interval is formed on the surface of the n-type cladding layer 103 using a photolithography method. For example, a mask pattern is formed in which a concave pattern or a convex pattern is repeated with an interval of 1.0 μm to 3.0 μm. In addition, the pattern for a recessed part or the pattern for a convex part is formed with arrangement | positioning, such as a matrix form and a honeycomb form, for example. Then, using the formed mask pattern as a mask, the concavo-convex shape portion 103a is formed on the surface of the n-type cladding layer 103 using a wet etching method. As a result, a bonded structure 1g having the uneven portion 103a is formed.

  Subsequently, a mask pattern for separating the light emitting elements is formed on the surface of the bonding structure 1g by using a photolithography method. That is, a mask pattern for separating light emitting elements is formed on the surface of the n-type cladding layer 103 of the bonded structure 1g. Using the mask pattern as a mask, the light emitting elements are separated by removing the surface from the n-type cladding layer 103 to the p-type contact layer 109 by wet etching. As a result, as shown in FIG. 2H, a bonded structure 1h in which a plurality of light emitting elements are separated is formed. Note that the side surface 10a is a surface exposed by wet etching, and has a smooth surface as compared with the case where the semiconductor multilayer structure 10 is mechanically cut.

  Next, the back electrode 210 is formed on substantially the entire back surface of the support substrate 20 by vacuum deposition. The back electrode 210 is formed by depositing Ti and Au on the bottom surface of the support substrate 20 in this order. Thereafter, between the contact portion 120 and the p-type contact layer 109, between the first surface electrode 110 and the second surface electrode 112 and the n-type contact layer 101, between the contact electrode 206 and the support substrate 20, and the back electrode. An alloying process, which is an alloying process for forming respective electrical bonds between 210 and the support substrate 20, is applied to the bonded structure 1 h including the back electrode 210. As an example, the bonded structure 1h is subjected to heat treatment at 400 ° C. for 5 minutes in a nitrogen atmosphere as an inert atmosphere. Subsequently, the pad electrode 115 is formed on the surfaces of the first surface electrode 110 and the second surface electrode 112 by using a photolithography method and a vacuum evaporation method. The pad electrode 115 is formed by, for example, depositing Ti and Au on the surfaces of the first surface electrode 110 and the second surface electrode 112 in this order. As a result, a bonded structure 1i as shown in FIG. 2I is formed.

  Then, using a dicing apparatus having a dicing blade, the bonded structure 1i is separated. Thereby, as shown to FIG. 2J, the several light emitting element 1 which concerns on this Embodiment is formed. In this case, the side surface 10b is generated in the region mechanically cut by the dicing blade. Since the side surface 10b is a mechanically cut region, there are large irregularities compared to the surface of the side surface 10a.

  As an example, the light emitting device 1 manufactured through the steps of FIGS. 2A to 2J is a light emitting diode having a large current application type device having a substantially square shape with a planar size of 1 mm square (planar size) (Light Emitting). Diode: LED). The light-emitting element 1 is die-bonded to the TO-46 stem using a conductive bonding material, and the first surface electrode 110 and a predetermined region of the TO-46 stem, and the second surface electrode 112 and the TO-46. Each predetermined region of the stem is connected with a wire such as Au. Thereby, the characteristic of the light emitting element 1 can be evaluated.

  Specifically, the initial characteristics of the light-emitting element 1 manufactured in this manufacturing process were evaluated without applying a resin mold. First, current was supplied to both the first surface electrode 110 and the second surface electrode 112 to evaluate the characteristics of the light emitting element 1. When a direct current of 1000 mA was supplied to the light emitting element 1 as a forward current, the forward voltage was 2.65 V and the light emission output was 615 mW.

  Next, a light emitting device was prepared in which only a predetermined region of the first surface electrode 110 and the TO-46 stem was wire bonded. That is, in this light emitting element, no current is supplied to the second surface electrode 112. The initial characteristics of this light emitting element were evaluated. When a direct current of 1000 mA was supplied to the first surface electrode 110 as a forward current, the light emitting element did not emit light.

  FIG. 3 shows currents when wire bonding is performed to both the first surface electrode and the second surface electrode of the light emitting device according to the first embodiment of the present invention and when the first surface electrode is actually wire bonded. -Shows the light output characteristics.

  When a direct current is supplied to the light emitting element 1 by connecting wires to both the first surface electrode 110 and the second surface electrode 112 of the light emitting element 1, the light emission output also increases linearly as the supplied current value increases. (In FIG. 3, this is indicated by “both wires”). However, when a direct current is supplied to the light emitting element 1 by connecting a wire only to the first surface electrode 110 of the light emitting element 1, the light emission output increases linearly until the supplied current is about 500 mA. The emission output decreased at about 500 mA or more. When the current value was further increased to 1000 mA, the light-emitting element 1 was turned off (indicated as “one wire” in FIG. 3). This was considered to be due to the fact that the current supplied to the light emitting element 1 was concentrated on the active layer 105 immediately below the first surface electrode 110 in the case of a single wire.

  As described above, the light-emitting element 1 according to the present embodiment supplies current to the light-emitting element 1 when a failure occurs in the wire connected to either the first surface electrode 110 or the second surface electrode 112. In addition, it was shown that the failure of the wire can be found by the fact that the light emitting element 1 does not emit light.

(Comparative example)
FIG. 4 shows an outline of the upper surface of the light emitting device according to the comparative example.

  The light emitting element 2 according to the comparative example has the same configuration as the light emitting element 1 except that the shape of the surface electrode is different from that of the light emitting element 1 according to the first embodiment of the present invention. Therefore, detailed description is omitted except for the differences.

  The light emitting element 2 according to the comparative example is configured as a single surface electrode 111 in which the first surface electrode 110 and the second surface electrode 112 are connected by the connection portion 11c. That is, in the light emitting element 2, a single surface electrode 111 is formed on the surface of the n-type cladding layer 103. The surface electrode 111 includes two circular electrodes 111a and a plurality of linear electrodes 111b. The cross-sectional area of each of the plurality of linear electrodes 111b and the cross-sectional area of the connection portion 111c are the same.

  The light-emitting element 2 according to the comparative example is die-bonded to the TO-46 stem using a conductive bonding material, and one circular electrode 111a and a predetermined region of the TO-46 stem, and the other circular electrode 111a and the TO- Each of the predetermined areas of 46 stems was connected by a wire such as Au. And the expected characteristic of the light emitting element 2 was evaluated, without giving a resin mold. When a current of 1000 mA was supplied to the light emitting element 2 as a forward current, the forward voltage was 2.25 V and the light emission output was 610 mW.

  Next, a light emitting device was prepared in which only one circular electrode 111a and a predetermined region of the TO-46 stem were wire bonded. That is, in this light emitting element, no current is supplied to the light emitting element 2 from the other circular electrode 111a. The initial characteristics of this light emitting element were evaluated. As a result, when a current of 1000 mA was supplied to one of the circular electrodes 111a as a forward current, the forward voltage was 2.78 V and the light emission output was 595 mW. In the light emitting element 2 according to the comparative example, even when one of the two wires supplying current to the light emitting element 2 is cut, the light emitting element 2 emits light, so that it is not possible to detect a defect in the wire. Indicated.

(Effects of the first embodiment)
The light emitting element 1 according to the present embodiment includes a plurality of electrodes for current injection for supplying current to the active layer 105 above the n-type cladding layer 103. That is, the light emitting element 1 can supply current to the active layer 105 from both the first surface electrode 110 and the second surface electrode 112 that is not electrically connected to the first surface electrode 110. As a result, the light emitting element 1 can spread the current supplied to the active layer 105 in the horizontal direction of the active layer 105, and suppress the current from being concentrated on a part of the active layer 105. Reliability can be improved.

  In the present embodiment, the first surface electrode 110 and the second surface electrode 112 are not electrically connected. Therefore, when a current is injected only into one of the first surface electrode 110 and the second surface electrode 112, the current concentrates on the active layer 105 corresponding to the region immediately below the surface electrode into which the current has been injected. In this case, the active layer 105 does not emit light due to a rise in the active layer temperature of a part of the active layer 105 where current is concentrated. Therefore, according to the light emitting element 1 according to the present embodiment, for example, either the wire connected to the first surface electrode 110 or the wire connected to the second surface electrode 112 is cut or damaged. In this case, even if a current is supplied to the light-emitting element 1, the light-emitting element 1 does not emit light, so that a wire defect can be easily detected. Thus, according to the present embodiment, defects such as wires can be easily found in the pre-shipment inspection performed after the light emitting element 1 is manufactured, and the highly reliable light emitting element 1 can be provided to the market.

[Second Embodiment]
FIG. 5 shows an outline of the upper surface of the light emitting device according to the second embodiment of the present invention.

  The light emitting element 3 according to the second embodiment of the present invention is the first except that the first surface electrode 110 and the second surface electrode 112 are electrically connected by a connection electrode as fine reselection. The light emitting element 1 according to the embodiment has substantially the same configuration. Therefore, detailed description is omitted except for the differences.

  The light emitting element 3 includes a first surface electrode 110 and a second surface electrode 112 on the light extraction surface side of the n-type cladding layer 103. In the light emitting element 3, the first surface electrode 110 and the second surface electrode 112 are formed from the first connection electrode 110 c extending from the first surface electrode 110 toward the second surface electrode 112 and the second surface electrode 112. The second connection electrode 112c extending toward the first surface electrode 110 side is electrically connected.

  The cross-sectional area of the first connection electrode 110c and the cross-sectional area of the second connection electrode 112c are smaller than the cross-sectional area of the plurality of first linear electrodes 110b and the cross-sectional area of the plurality of second linear electrodes 112b, respectively. The That is, in the top view, the width of the first connection electrode 110 and the width of the second connection electrode 112c are formed narrower than the width of the first linear electrode 110b and the width of the second linear electrode 112b, respectively. . As an example, the first connection electrode 110 and the second connection electrode 112c are formed to have a width of about 10 μm. Thus, when a current is supplied to either the first surface electrode 110 or the second surface electrode 112, no current is substantially supplied from one surface electrode to which the current is supplied to the other surface electrode. The same effects as those of the light-emitting element 1 according to the first embodiment are obtained.

  While the embodiments of the present invention have been described above, the embodiments described above do not limit the invention according to the claims. In addition, it should be noted that not all the combinations of features described in the embodiments are essential to the means for solving the problems of the invention.

It is a typical longitudinal cross-sectional view of the light emitting element which concerns on 1st Embodiment. (A) is a top view of the light emitting device according to the first embodiment, and (b) is a top view of the light emitting device when the light emitting device is cut along the line AA in FIG. 1A. It is a figure of the manufacturing process of the light emitting element which concerns on 1st Embodiment. It is a figure of the manufacturing process of the light emitting element which concerns on 1st Embodiment. It is a figure of the manufacturing process of the light emitting element which concerns on 1st Embodiment. It is a figure of the manufacturing process of the light emitting element which concerns on 1st Embodiment. It is a figure of the manufacturing process of the light emitting element which concerns on 1st Embodiment. It is a figure of the manufacturing process of the light emitting element which concerns on 1st Embodiment. It is a figure of the manufacturing process of the light emitting element which concerns on 1st Embodiment. It is a figure of the manufacturing process of the light emitting element which concerns on 1st Embodiment. It is a figure of the manufacturing process of the light emitting element which concerns on 1st Embodiment. It is a figure of the manufacturing process of the light emitting element which concerns on 1st Embodiment. The figure which shows the current-light output characteristic in each when wire bonding is carried out to both the 1st surface electrode and 2nd surface electrode of the light emitting element which concerns on 1st Embodiment, and when the 1st surface electrode is actually wire-bonded. It is. It is a top view of the light emitting element concerning a comparative example. It is a top view of the light emitting element concerning a 2nd embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2, 3 Light emitting element 1a Semiconductor laminated structure 1b, 1c, 1d, 1e, 1f, 1g, 1h, 1i Junction structure 10 Semiconductor laminated structure 10a Side surface 10b Side surface 11 Semiconductor laminated structure 20 Support substrate 100 N-type GaAs substrate 101 n-type contact layer 102 etching stop layer 103 n-type cladding layer 103a concavo-convex shape portion 105 active layer 107 p-type cladding layer 109 p-type contact layer 110 first surface electrode 110a, 112a circular electrode 110b first linear electrode 110c first Connection electrode 111 Surface electrode 111a Circular electrode 111b Linear electrode 111c Connection portion 112 Second surface electrode 112b Second linear electrode 112c Second connection electrode 115 Pad electrode 120 Contact portion 120a Branched contact portion 130 Reflective portion 132 Reflective layer 134, 204 bar A layer 136,202 bonding layer 136a, 202a bonding surface 140 transparent layer 140a opening 200 adhesive layer 206 contacts the electrode 210 back-surface electrode

Claims (5)

A first conductivity type first semiconductor layer; a second conductivity type second semiconductor layer different from the first conductivity type; and an active layer sandwiched between the first semiconductor layer and the second semiconductor layer. A semiconductor laminated structure;
A first electrode that is provided on a side opposite to the side in contact with the active layer of the first semiconductor layer, is provided at a position apart from the first electrode, and a first electrode that supplies current to the first semiconductor layer; A second electrode for supplying a current to one semiconductor layer;
The active layer emits light when a current is supplied to both the first electrode and the second electrode, and the supplied current spreads in a horizontal direction of the active layer.   When the current is supplied to either the first electrode or the second electrode, the active layer is directly below either the first electrode to which current is supplied or the second electrode to which current is supplied. The light emitting device according to claim 1, wherein the current supplied to a part of the active layer does not emit light due to concentration. The first electrode includes a first circular electrode and a first linear electrode electrically connected to the first circular electrode;
The second electrode has a second circular electrode and a second linear electrode electrically connected to the second circular electrode,
The light emitting device according to claim 2, wherein the first linear electrode is not electrically connected to the second linear electrode. The first electrode includes a first circular electrode, a first linear electrode electrically connected to the first circular electrode, and a first connection electrode having a cross-sectional area smaller than a cross-sectional area of the first linear electrode. Have
The second electrode includes a second circular electrode, a second linear electrode electrically connected to the second circular electrode, and a cross-sectional area smaller than a cross-sectional area of the second linear electrode, The light emitting element according to claim 2, further comprising a second connection electrode electrically connected to the connection electrode. Further comprising a support substrate having a reflective portion;
5. The light emitting device according to claim 3, wherein the semiconductor multilayer structure is supported by the support substrate via a transparent layer including a contact portion that electrically connects the semiconductor multilayer structure and the reflective portion.

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