KR101300263B1 - Semiconductor light emitting device - Google Patents

Abstract

The present disclosure discloses a first semiconductor layer having a first conductivity type, a second semiconductor layer having a second conductivity type different from the first conductivity type, and a combination of electrons and holes located between the first semiconductor layer and the second semiconductor layer. A plurality of semiconductor layers including an active layer for generating light by; And a first electrode formed on the first semiconductor layer from which the plurality of semiconductor layers are removed and exposed, the first electrode having a branch electrode portion extending to supply current to the first semiconductor layer and a bonding pad portion to which the wire is bonded. The portion has a first contact layer in contact with the first semiconductor layer, a first bonding layer formed on the first contact layer and to which the wire is bonded, and the branch electrode portion has light reflectance higher than that of the first bonding layer, and the light is emitted from the exposed active layer. It relates to a semiconductor light emitting device comprising a; first electrode having a branch electrode portion reflecting layer to reflect.

Description

 Technical Field [0001] The present invention relates to a semiconductor light emitting device,

The present disclosure generally relates to a semiconductor light emitting device, and more particularly, to a semiconductor light emitting device having an improved external quantum efficiency by reducing light absorption loss caused by an electrode.

Herein, the background art relating to the present disclosure is provided, and these are not necessarily meant to be known arts.

1 is a view showing an example of a conventional Group III nitride semiconductor light emitting device. The group III nitride semiconductor light emitting device includes a substrate 10 (eg, a sapphire substrate), a buffer layer 20 grown on the substrate 10, an n-type group III nitride semiconductor layer 30 grown on the buffer layer 20, and an n-type 3 Current diffusion conductive film formed on the active layer 40 grown on the group nitride semiconductor layer 30, the p-type group III nitride semiconductor layer 50 grown on the active layer 40, and the p-type group III nitride semiconductor layer 50. 60, the p-side bonding pad 70 formed on the current spreading conductive film 60, the n-type III-nitride semiconductor layer exposed by the mesa-etched p-type III-nitride semiconductor layer 50 and the active layer 40 And an n-side bonding pad 80 and a passivation layer 90 formed on the 30.

The current diffusion conductive film 60 is provided to supply current to the entire p-type III nitride semiconductor layer 50 well. The current diffusion conductive film 60 is formed over substantially the entire surface of the p-type III nitride semiconductor layer 50. For example, ITO, ZnO, or Ni and Au may be used to form the light-transmitting conductive film, or Ag may be used Thereby forming a reflective conductive film.

The p-side bonding pad 70 and the n-side bonding pad 80 are metal electrodes for supplying current and wire bonding to the outside, for example, nickel, gold, silver, chromium, titanium, platinum, palladium, and rhodium. And iridium, aluminum, tin, indium, tantalum, copper, cobalt, iron, ruthenium, zirconium, tungsten, molybdenum, or any combination thereof.

The protective film 90 is formed of a material such as silicon dioxide and may be omitted.

In accordance with the large area and high power consumption of the semiconductor light emitting device, branch electrodes and a plurality of bonding pads are introduced for smooth current diffusion in the semiconductor light emitting device. For example, FIG. 2 is a view showing an example of the electrode structure described in US Pat. No. 6,307,218. As the semiconductor light emitting device becomes larger in area, between the p-side bonding pad 710 and the n-side bonding pad 810, and the like. A technique for improving current spreading by having branch electrodes 910 having a gap is described.

However, since metal electrodes such as bonding pads and branch electrodes have a thick thickness and have a large light absorption loss, there is a problem in that light extraction efficiency of the semiconductor light emitting device is reduced.

This will be described later in the Specification for Implementation of the Invention.

SUMMARY OF THE INVENTION Herein, a general summary of the present disclosure is provided, which should not be construed as limiting the scope of the present disclosure. of its features).

According to one aspect of the disclosure, a first semiconductor layer having a first conductivity type, a second semiconductor layer having a second conductivity type different from the first conductivity type, and a first semiconductor is provided. A plurality of semiconductor layers positioned between the layer and the second semiconductor layer and including an active layer that generates light by combining electrons and holes; And a first electrode formed on the first semiconductor layer from which the plurality of semiconductor layers are removed and exposed, the first electrode having a branch electrode portion extending to supply current to the first semiconductor layer and a bonding pad portion to which the wire is bonded. The portion has a first contact layer in contact with the first semiconductor layer, a first bonding layer formed on the first contact layer and to which the wire is bonded, and the branch electrode portion has light reflectance higher than that of the first bonding layer, and the light is emitted from the exposed active layer. Provided is a semiconductor light emitting device comprising a; first electrode having a branch electrode portion reflecting layer to reflect.

According to another aspect of the present disclosure (According to one aspect of the present disclosure), a first semiconductor layer having a first conductivity type, a second semiconductor layer having a second conductivity type different from the first conductivity type, and a first semiconductor A plurality of semiconductor layers positioned between the layer and the second semiconductor layer and including an active layer that generates light by combining electrons and holes; And a first electrode formed on the first semiconductor layer to which the plurality of semiconductor layers are removed and exposed, wherein the first electrode is in contact with the first semiconductor layer and the first bonding layer is formed on the first contact layer and the wires are bonded. And a first electrode formed between the first contact layer and the first bonding layer and having a first reflecting layer reflecting light from the exposed active layer with a higher reflectance than the first bonding layer. An element is provided.

This will be described later in the Specification for Implementation of the Invention.

FIG. 1 is a view showing an example of a conventional Group III nitride semiconductor light emitting device,
2 is a view showing an example of an electrode structure described in US Pat. No. 6,307,218;
3 is a view showing an example of a semiconductor light emitting device according to the present disclosure,
FIG. 4 is a cross-sectional view of the semiconductor light emitting device shown in FIG. 3 taken along line AA,
FIG. 5 is a diagram illustrating a cross section taken along line BB of the semiconductor light emitting device illustrated in FIG. 3, illustrating a manufacturing process of the semiconductor light emitting device;
6 is a cross-sectional view of the semiconductor light emitting device illustrated in FIG. 3 taken along a line CC;
7 illustrates another example of the semiconductor light emitting device according to the present disclosure;

The present disclosure will now be described in detail with reference to the accompanying drawing (s).

3 is a diagram illustrating an example of a semiconductor light emitting device 300 according to the present disclosure. 4 is a cross-sectional view of the semiconductor light emitting device 300 illustrated in FIG. 3 taken along line A-A.

The semiconductor light emitting device 300 includes a substrate 310, a plurality of semiconductor layers, a first electrode 380, a current spreading conductive film 360, and a second electrode 370. The plurality of semiconductor layers includes a buffer layer 320, a first semiconductor layer 330, an active layer 340, and a second semiconductor layer 350 stacked on the substrate 310.

Hereinafter, when the first semiconductor layer 330, the second semiconductor layer 350, and the active layer 340 are formed of a III-V group compound semiconductor, Al (x) Ga (y) In (1-xy) N ( The case where it forms with the group III nitride semiconductor represented by 0 <= <= 1, 0 <= y <= 1, 0 <= x + y <= 1) is demonstrated to an example.

The substrate 310 may be a GaN-based substrate as a homogeneous substrate, a sapphire substrate, a SiC substrate, or a Si substrate as a heterogeneous substrate. Any substrate may be used as long as the group III nitride semiconductor layer can be grown.

The first semiconductor layer 330 has a first conductivity type, and the second semiconductor layer 350 is provided to have a second conductivity type different from the first conductivity type. In the present disclosure, the first semiconductor layer 330 is an n-type nitride semiconductor layer 330 (eg, an n-type GaN layer), and the second semiconductor layer 350 is a p-type nitride semiconductor layer 350 (eg, p-type GaN layer), the first electrode 380 is used as the n-side electrode 380, and the second electrode 370 is used as the p-side electrode 370.

Unexplained numbers 382, 383, 384, and 386 are described later.

FIG. 5 is a cross-sectional view of the semiconductor light emitting device illustrated in FIG. 3 taken along the line B-B, illustrating a manufacturing process of the semiconductor light emitting device.

First, an n-type nitride semiconductor layer 330, an active layer 340, and a p-type nitride semiconductor layer 350 are formed on the substrate 310. The semiconductor layers epitaxially grown on the substrate 310 are mainly grown by organometallic vapor phase growth (MOCVD), and each layer may further include detailed layers as necessary.

After the plurality of semiconductor layers are formed on the substrate 310, the p-type nitride semiconductor layer 350 and the active layer 340 are etched in the form of mesas, and as shown in FIG. 5A, the n-side electrode 380. A portion of the n-type nitride semiconductor layer 330 is exposed, including a region corresponding to the? As a method of removing a plurality of semiconductor layers, a dry etching method, for example, an inductively coupled plasma (ICP) may be used.

Next, current spreading conduction on the p-type nitride semiconductor layer 350, as shown in FIG. 5B, by using a sputtering method, an E-beam evaporation method, a thermal evaporation method, and the like. A film 360 is formed. Alternatively, the mesa etching process may be performed after the current diffusion conductive film 360 is formed. The current spreading conductive film 360 improves the current density uniformity of the p-type nitride semiconductor layer 350 as a whole so as to emit surface light. The current spreading conductive film 360 is mainly formed of ITO, ZnO, or Ni / Au. The current diffusion conductive film 360 is formed in a large portion of the light emitting region. If the current diffusion conductive film 360 is too thin, the current diffusion conductive film 360 is disadvantageous to current diffusion and the driving voltage is high. Can be.

Subsequently, by using a method such as a sputtering method, an electron beam evaporation method, a thermal evaporation method, or the like, as shown in FIG. 380 and the p-side electrode 370 are formed on the current spreading conductive film 360.

For example, the n-side electrode 380 includes an n-side bonding pad portion 381 and an n-side branch electrode portion 385, and the p-side electrode 370 has a p-side bonding pad portion 371 and a p-side branch. The electrode part 375 is included.

The semiconductor light emitting device 300 illustrated in FIG. 3 is formed to be long to one side to increase in size, and has a substantially rectangular planar shape. Therefore, the semiconductor light emitting device 300 has a long side and a short side.

The n-side bonding pad portion 381 and the p-side bonding pad portion 371 are located on opposite short sides. The n-side branch electrode portion 385 extends from the n-side bonding pad portion 381 toward the p-side bonding pad portion 371 along the center of the semiconductor light emitting device 300. The two p-side branch electrode portions 375 extend from the p-side bonding pad portion 371 and extend to both sides of the n-side branch electrode portion 385.

The shape and arrangement of the electrodes can be variously changed. For example, unlike the example illustrated in FIG. 3, at least one of the n-side bonding pad portion 381 and the p-side bonding pad portion 371 may be formed on the substrate 310 outside the plurality of semiconductor layers. The number and arrangement of the branch electrode part 385 and the p-side branch electrode part 375 may be changed according to the size and shape of the semiconductor light emitting device 300. In addition, an n-type nitride semiconductor layer 330 may be formed on the active layer 340, and a p-type nitride semiconductor layer 350 may be formed below the active layer 340, in which case the p-side electrode 370 and n The vertical position of the side electrode 380 is also changed.

On the other hand, the light generated in the active layer 340 is emitted to the top and bottom and side surfaces of the plurality of semiconductor layers. A significant amount of light is mesaetched and emitted to the side of the exposed plurality of semiconductor layers. In addition, a part of light is reflected upward by the substrate 310.

The n-side electrode 380 and the p-side electrode 380 are made of a metal having good bonding properties, good electrical properties, and made of a plurality of metal layers to prevent peeling. The height of the electrode is not small compared to the height of the plurality of semiconductor layers exposed by mesa etching, and thus the light emitted through the cross-sections of the plurality of mesa-etched semiconductor layers is n-side bonding pad portion 381 and n-side branch electrode portion 385. The light absorbing loss can be caused by the side of the.

In view of this, lowering the height of the electrode may be considered to reduce light absorption. However, while the size of the electrode occupies a considerable portion in the semiconductor light emitting device 300, the metal has not only light absorption but also light reflectivity. In the present disclosure, as opposed to lowering the height of the electrode, a reflective layer made of a metal having excellent reflectance is introduced into the electrode, and the reflective layer is formed higher than other layers of the electrode to sufficiently reflect light.

As described above, the semiconductor light emitting device 300 according to the present disclosure has a configuration that satisfies the bonding properties and electrical characteristics required for the n-side electrode 380 or the p-side electrode 380, and improves light reflection, thereby improving light extraction efficiency. Is improved.

The n-side electrode 380 faces the side of the p-type nitride semiconductor layer 350 exposed by mesa etching, the side of the active layer 340, and the side of the n-type nitride semiconductor layer 330, and thus the n-side bonding pad portion 381. ) And the n-side branch electrode part 385 absorb light not only reflected from the substrate 310 but also light from side surfaces of the plurality of etched and exposed semiconductor layers. Therefore, in order to reduce light absorption by the electrode, it is effective to reduce the light absorption by the n-side bonding pad portion 381 and the n-side branch electrode portion 385.

6 is a cross-sectional view of the semiconductor light emitting device 300 illustrated in FIG. 3 taken along the line C-C.

For example, the n-side bonding pad portion 381 and the n-side branch electrode portion 385 may be sequentially stacked on the first contact layer 382, the first reflective layer 383, the additional layer 384, and the first layer. Bonding layer 386.

The first contact layer 382 is selected as a metal having good bonding and electrical contact properties with the n-type nitride semiconductor layer 330, and the first reflective layer 383 is selected as a metal having excellent reflectance and is etched and exposed. Higher for each of the first bonding layer 386, the first contact layer 382, and the additional layer 384 to sufficiently reflect light from the sides of the semiconductor layer. The first bonding layer 386 is selected as a metal having good bonding properties for wire bonding of the n-side bonding pad portion 381. It is provided for the protection of the bonding between the first reflective layer 383 and the first bonding layer 386 of the additional layer 384 or the properties of the first bonding layer 386 and the first reflective layer 383.

For example, the n-side bonding pad portion 381 and the n-side branch electrode portion 385 are Cr (382) / Al (383) / Ti (384) / as shown in FIGS. 4, 5C, and 6. It can be composed of Au (386), in addition to Cr / Ag / Ti / Au, Cr / Al / Ni / Au, Cr / Ag / Ni / Au, Ti / Al / Ti / Au, Ti / Ag / Ti / Au , Ti / Al / Ni / Au, Ti / Ag / Ni / Au, etc., and it can be composed of various combinations.The important point in this layer composition is that the Al or Ag layer, which is the reflective layer, is made thicker than other layers, and other layers are possible. The thinner design improves the reflection of the light emitted from the mesa etching surface.

Cr 382 or Ti having good contact with the n-type nitride semiconductor layer 330 is used as the first contact layer 382, and Au 386 having good bonding characteristics is used as the first bonding layer 386. The first reflecting layer 383 is formed by depositing Al (383) or Ag having excellent reflectance. An additional layer 384 is used as Ti or Ni, which bonds well with Al 383 and Au 386 and becomes a barrier.

In FIG. 5C, the heights of the n-side bonding pad portion 381 and the n-side branch electrode portion 385 are illustrated for convenience. For example, it is formed of Cr (20 Pa) / Al (2um) / Ti (500 Pa) / Au (2000 Pa). As described above, the first reflective layer 383 has a thickness (height) thicker than that of each of the first bonding layer 386 and the additional layer 384. In the above example, the first reflective layer 383 preferably has a height of 5000 GPa or more, and in consideration of the reflection effect and electrical conductivity, the first reflective layer 383 preferably has a height of 1 μm or more.

3 to 6 illustrate an example in which the n-side bonding pad portion 381 and the n-side branch electrode portion 385 have the same layer structure, the n-side bonding pad portion 381 and the n-side branch electrode portion 385 are illustrated. The layer structure of is not necessarily the same, and the reflection layer may be formed higher than other layers such as a bonding layer because light absorption loss is a problem. For example, when light absorption by the n-side branch electrode portion 385 is particularly problematic than light absorption by the n-side bonding pad portion 381, the n-side bonding pad portion 381 is Cr / Al / Ti /. Although formed of Au, the n-side branch electrode portion 385 may be made of Cr / Al or Cr / Ag, and the n-side bonding pad portion 381 may be formed of the Al layer (branch electrode portion reflection layer) of the n-side branch electrode portion 385. It may be formed higher than each of the other layers of).

7 is a diagram illustrating another example of the semiconductor light emitting device 700 according to the present disclosure.

The semiconductor light emitting device 700 is described with reference to FIGS. 3 to 6 except that the side surfaces of the n-side branch electrode portion 785 and the n-side bonding pad portion are formed to have an inclination with respect to the direction perpendicular to the substrate 705. It is substantially the same as the semiconductor light emitting device 300. Therefore, redundant description is omitted.

For example, the n-side bonding pad portion and the n-side branch electrode portion 785 are made of Cr / Al / Ti / Au, and the side surface thereof is inclined with respect to the perpendicular direction to the substrate 705 as shown in FIG. It is formed to have a cross-section has a trapezoidal shape. Therefore, light emitted from the plurality of semiconductor layers is more reflected by the n-side bonding pad portion and the n-side branch electrode portion 785.

Hereinafter, various embodiments of the present disclosure will be described.

(1) The branch electrode part reflective layer is made of at least one of Al or Ag.

(2) The branch electrode part reflective layer is made of Al.

(3) The branch electrode portion reflective layer has a height of 5000 mV or more.

(4) The semiconductor light emitting device according to claim 1, wherein the branch electrode part reflection layer has a height of 1 μm or more.

(5) The branch electrode portion reflective layer has a thickness greater than that of the first bonding layer.

(6) The semiconductor light emitting device according to claim 1, wherein the bonding pad portion has an additional layer between the first contact layer and the first bonding layer, and the branch electrode portion reflecting layer has a thickness thicker than that of each of the additional layer and the first bonding layer.

(7) A semiconductor light emitting element, characterized in that the plurality of semiconductor layers are made of a group III nitride semiconductor.

(8) The bonding pad portion includes a bonding pad portion reflective layer having a higher reflectance than the first bonding layer and reflecting light from the exposed active layer formed between the first contact layer and the first bonding layer. A semiconductor light emitting device.

(9) The semiconductor light emitting device according to claim 9, wherein the bonding pad portion reflection layer is made of at least one of Al and Ag.

(10) The semiconductor light emitting device according to claim 10, wherein the bonding pad portion reflection layer is made of Al.

(11) A semiconductor light emitting element, wherein the bonding pad portion reflection layer has a height of 5000 kPa or more.

(12) A semiconductor light emitting element, wherein the bonding pad portion reflection layer has a height of 1 μm or more.

(13) The semiconductor light emitting device according to claim 1, wherein the bonding pad portion has a thickness greater than that of the first bonding layer.

(14) A semiconductor light emitting element having an additional layer between the bonding pad portion reflective layer and the first bonding layer, wherein the bonding pad portion reflection layer has a thickness thicker than the additional layer and the first bonding layer.

According to the semiconductor light emitting device according to the present disclosure, the light absorption by the electrode is reduced and the external quantum efficiency is improved.

300: semiconductor light emitting element 370: p-side electrode
380: n-side electrode 381: n-side bonding pad portion
382: Cr 383: Al
384 Ti 385 n-side branch electrode portion
386: Au

Claims (24)

A first semiconductor layer having a first conductivity type, a second semiconductor layer having a second conductivity type different from the first conductivity type, and positioned between the first semiconductor layer and the second semiconductor layer, A plurality of semiconductor layer including an active layer for generating a; And
A portion of the second semiconductor layer, the active layer, and the first semiconductor layer is formed on the first semiconductor layer exposed through mesa etching, and is a bonding pad portion in which a branch electrode portion and a wire are bonded to extend a current to supply the first semiconductor layer. The first electrode is divided; The bonding pad part has a plurality of metal layers including a first contact layer in contact with the first semiconductor layer and a first bonding layer formed on the first contact layer and bonded with wires, and the branch electrode part It has a higher reflectance than the first contact layer and the first bonding layer in contact with the first semiconductor layer and is formed on the first contact layer and reflects light from the exposed active layer to prevent light absorption loss by the side surfaces of the branch electrode portions. And a first electrode having a plurality of metal layers including a branch electrode part reflective layer.
The semiconductor light emitting device according to claim 1, wherein the first contact layer, the branch electrode reflecting layer, and the first bonding layer directly face the side surface of the second semiconductor layer, the side surface of the active layer, and the side surface of the first semiconductor layer. The method according to claim 1,
The branch electrode reflective layer is made of at least one of Al and Ag. The method according to claim 1,
The branch electrode reflective layer is made of Al. The method according to claim 1,
The branch electrode reflecting layer has a thickness of 5000 kPa or more. The method according to claim 1,
A semiconductor light emitting device, wherein the branch electrode reflecting layer has a thickness of 1 μm or more. The method according to claim 1,
The branch electrode reflecting layer has a thickness greater than that of the first bonding layer. The method according to claim 1,
And a bonding pad portion having an additional layer between the first contact layer and the first bonding layer, wherein the branch electrode portion reflecting layer has a thickness thicker than each of the additional layer and the first bonding layer. The method according to claim 1,
The semiconductor light emitting device, characterized in that the plurality of semiconductor layers are made of a group III nitride semiconductor. The method according to claim 1,
The bonding pad portion includes a bonding pad portion reflection layer having a higher reflectance than the first bonding layer and reflecting light from an active layer formed between the first contact layer and the first bonding layer and exposed. device. The method according to claim 9,
The bonding pad portion reflective layer is made of at least one of Al and Ag. The method according to claim 9,
The bonding pad portion reflective layer is made of Al. The method according to claim 9,
The bonding pad portion reflective layer has a thickness of 5000 kPa or more. The method according to claim 9,
The bonding pad portion reflective layer has a thickness of 1 μm or more. The method according to claim 9,
The bonding pad portion reflective layer has a thickness greater than that of the first bonding layer. The method according to claim 9,
And an additional layer between the bonding pad portion reflective layer and the first bonding layer, wherein the bonding pad portion reflective layer has a thickness greater than each of the additional layer and the first bonding layer. A first semiconductor layer having a first conductivity type, a second semiconductor layer having a second conductivity type different from the first conductivity type, and positioned between the first semiconductor layer and the second semiconductor layer, A plurality of semiconductor layer including an active layer for generating a; And
A first electrode formed on the first semiconductor layer to which the second semiconductor layer, the active layer, and a portion of the first semiconductor layer are mesa-etched and exposed; formed on the first contact layer and the first contact layer in contact with the first semiconductor layer From the active layer exposed between the first bonding layer and the first bonding layer to which the wire is bonded and formed between the first contact layer and the first bonding layer and to prevent light absorption loss by the side of the first electrode. And a first electrode having a first reflecting layer that reflects light.
And a first contact layer, a first reflective layer, and a first bonding layer of the first electrode directly face the side surface of the second semiconductor layer, the side surface of the active layer, and the side surface of the first semiconductor layer. 18. The method of claim 16,
The first electrode further comprises a branch electrode portion extending to supply a current to the first semiconductor layer. 18. The method of claim 16,
The first reflective layer is made of at least one of Al or Ag, the semiconductor light emitting device. 18. The method of claim 16,
The semiconductor light emitting device according to claim 1, wherein the first reflective layer is made of Al. 18. The method of claim 16,
The semiconductor light emitting device according to claim 1, wherein the first reflective layer has a thickness of 5000 mW or more. 18. The method of claim 16,
A semiconductor light emitting device, characterized in that the first reflective layer has a thickness of 1um or more. 18. The method of claim 16,
The first reflective layer has a thickness greater than that of the first bonding layer. 18. The method of claim 16,
And an additional layer between the first reflective layer and the first bonding layer, wherein the first reflective layer has a thicker thickness than each of the additional layer and the first bonding layer. 24. The method of claim 23,
The first contact layer, the first reflective layer, the additional layer and the first bonding layer are Cr (or Ti) / Al / Ti (or Ni) / Au or Cr (or Ti) / Ag / Ti (or Ni) / Au, respectively. A semiconductor light emitting device, characterized in that consisting of.

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