JP2016178228A - Light emission element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emission element that has high resistance to electrostatic discharge (ESD) in the reverse direction and can suppress reduction of the light emission efficiency.SOLUTION: A light-emitting element includes a first conductivity type semiconductor layer, an active layer disposed on the first conductivity type semiconductor layer, a second conductivity type semiconductor layer disposed on the active layer, a first electrode disposed on the first conductivity type semiconductor layer, a second electrode disposed on the second conductivity type semiconductor layer, and a discharge unit. The discharge portion is electrically connected to the first conductivity type semiconductor layer. The light-emitting element includes a first terminal which is disposed on the first conductivity type semiconductor layer separately from the first electrode, a second terminal which is electrically connected to the second conductivity type semiconductor layer, and an insulating member provided between the second terminal and the first terminal.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a light emitting element.

  Conventionally, in order to prevent deterioration and damage of the light emitting element due to electrostatic discharge (ESD), a light emitting element in which a discharge mechanism (MIM type tunnel junction structure) is provided in the light emitting element has been proposed (see Patent Document 1). The discharge mechanism (MIM type tunnel junction structure) is configured to include a lower metal layer, an insulating film, and an upper metal layer.

JP 2006-203160 A

  However, in the above discharge mechanism (MIM type tunnel junction structure), the lower metal layer is made of the same material as the n-side electrode, and the lower metal layer and the n-side electrode are electrically connected by wiring made of the same material. (See paragraph 0025 of Patent Document 1). For this reason, in said light emitting element, when a discharge function act | operated by the electrostatic discharge (ESD) of the reverse direction, the n side electrode and its peripheral part might deteriorate or be damaged, and there exists a possibility that luminous efficiency may fall.

  The above problem can be solved by, for example, the following means.

  A first conductivity type semiconductor layer, an active layer disposed on the first conductivity type semiconductor layer, a second conductivity type semiconductor layer disposed on the active layer, and disposed on the first conductivity type semiconductor layer A first electrode arranged on the second conductive type semiconductor layer, and a discharge part, wherein the discharge part is electrically connected to the first conductive type semiconductor layer, A first terminal disposed separately from the first electrode on the first conductive semiconductor layer; a second terminal electrically connected to the second conductive semiconductor layer; the first terminal; And an insulating member provided between the second terminal and the second terminal.

  According to the above means, it is possible to provide a light emitting element that has high resistance to reverse electrostatic discharge (ESD) and can suppress a decrease in light emission efficiency.

3 is a schematic plan view of the light emitting element according to Embodiment 1. FIG. It is AA sectional drawing in FIG. 6 is a schematic plan view of a light emitting device according to Embodiment 2. FIG. It is BB sectional drawing in FIG. 6 is a schematic plan view of a light emitting device according to Embodiment 3. FIG. It is CC sectional drawing in FIG. 6 is a schematic plan view of a light emitting element according to Embodiment 4. FIG. It is DD sectional drawing in FIG.

[Light Emitting Element According to Embodiment 1]
FIG. 1 is a schematic plan view of a light emitting device according to Embodiment 1, and FIG. 2 is a cross-sectional view taken along line AA in FIG. As shown in FIGS. 1 and 2, the light-emitting element 1 according to Embodiment 1 includes a first conductive semiconductor layer 10, an active layer 12 disposed on the first conductive semiconductor layer 10, and an active layer 12. A second conductive semiconductor layer 14 disposed on the first conductive semiconductor layer 10, a first electrode 16 disposed on the first conductive semiconductor layer 10, a second electrode 18 disposed on the second conductive semiconductor layer 14, and a discharge. The discharge part 20 is electrically connected to the first conductivity type semiconductor layer 10 and is disposed separately from the first electrode 16 on the first conductivity type semiconductor layer 10. And a second terminal 24 electrically connected to the second conductivity type semiconductor layer 14, and an insulating member 26 provided between the first terminal 22 and the second terminal 24. . The light emitting element 1 may have an insulating protective film 34. For the sake of explanation, the insulating protective film 34 is omitted in FIG. Details will be described below.

  As the first conductivity type semiconductor layer 10 and the second conductivity type semiconductor layer 14, semiconductor layers having different conductivity types are used. For example, when an n-type semiconductor layer is used as the first conductive semiconductor layer 10, a p-type semiconductor layer can be used as the second conductive semiconductor layer 14. When a p-type semiconductor layer is used as the first conductive semiconductor layer 10, an n-type semiconductor layer can be used as the second conductive semiconductor layer 14. As a semiconductor layer constituting the first conductivity type semiconductor layer 10 and the second conductivity type semiconductor layer 14, for example, a semiconductor layer using a nitride semiconductor can be used.

The active layer 12 is a light emitting layer, and preferably has a single quantum well structure or a multiple quantum well structure including a well layer and a barrier layer. A nitride semiconductor can be used as the active layer 12. For example, the well layer is formed of In _x Ga _1-x N (0 <x <1), and the barrier layer is In _y Ga _1-y N (0 ≦ y <x).

  For example, Ti / Rh / Au or Rh / W / Au can be used as the first electrode 16. Further, for example, Ti / Rh / Au or Rh / W / Au can be used as the second electrode 18. The same material may be used for the first electrode 16 and the second electrode 18.

(Discharge unit 20)
The discharge unit 20 includes a first terminal 22 electrically connected to the first conductivity type semiconductor layer 10, a second terminal 24 electrically connected to the second conductivity type semiconductor layer 14, and a first terminal 22 And an insulating member 26 provided between the second terminal 24 and the second terminal 24.

  The mechanism by which the discharge unit 20 discharges static electricity is as follows. That is, in the normal state, the first terminal 22 and the second terminal 24 of the discharge unit 20 are insulated via the insulating member 26. However, when electrostatic discharge (ESD) in the reverse direction occurs in the light emitting element 1, the insulating member 26 breaks down earlier than the active layer 12, the first conductive semiconductor layer 10, and the second conductive semiconductor layer 14. . Thereby, the first terminal 22 and the second terminal 24 are conducted earlier than the first electrode 16 and the second electrode 18 are conducted through the semiconductor layer stack including the active layer 12, and the static electricity is, for example, It is not the route of the first electrode 16 → the first conductive type semiconductor layer 10 → the active layer 12 → the second conductive type semiconductor layer 14 → the second electrode 18, but the first electrode 16 → the first conductive type semiconductor layer 10 → the first terminal. 22 → insulating member 26 → second terminal 24 → second conductive semiconductor layer 14 → second electrode 18 flows through the route. In addition, when the 1st electrode 16 is an anode side and the 2nd electrode 18 is a cathode side, although it flows in the reverse order, the same result is obtained. Therefore, deterioration and destruction of the active layer 12, the first conductive semiconductor layer 10, and the second conductive semiconductor layer 14 due to electrostatic discharge (ESD) are reduced. The forward current is a current that flows from the p-side electrode (anode side) to the n-side electrode (cathode side), and the opposite direction is the reverse direction. That is, the reverse direction refers to the direction from the first electrode 16 toward the second electrode 18 when the first electrode 16 is an n-side electrode and the second electrode 18 is a p-side electrode. Indicates a direction from the second electrode 18 toward the first electrode 16 when the second electrode 18 is an n-side electrode.

  The above mechanism reduces the deterioration and damage of the active layer 12, the first conductive type semiconductor layer 10, and the second conductive type semiconductor layer 14 due to reverse electrostatic discharge (ESD). The first terminal 22 is disposed on the first conductive semiconductor layer 10 separately from the first electrode 16. Therefore, when the discharge function is activated by reverse electrostatic discharge (ESD), it is possible to reduce the deterioration and damage of the first electrode 16 and its peripheral portion. In addition, a portion where the first terminal 22 and the second terminal 24 face each other, that is, a portion discharged by reverse electrostatic discharge (ESD) is not on the active layer 12 which is a light emitting region, but the first conductive semiconductor layer 10. By disposing it above, even if the first terminal 22 and the second terminal 24 change color due to discharge, the influence of light absorption due to the change in color can be reduced. Therefore, it is possible to provide the light emitting element 1 that has high resistance to electrostatic discharge (ESD) in the reverse direction and can suppress a decrease in light emission efficiency. The second terminal 24 may not be disposed separately from the second electrode 18, but is preferably disposed separately. Furthermore, it is preferable that one end of the second terminal 24 is in direct contact with the second conductivity type semiconductor layer 14. In this way, it is possible to reduce the deterioration and damage of the second electrode 18 and the surrounding area due to electrostatic discharge (ESD) in the reverse direction, and thus the reduction in luminous efficiency is further suppressed. The light emitting element 1 can be provided.

  The insulating member 26 may be provided between the first terminal 22 and the second terminal 24, but is preferably arranged so as to be sandwiched between the first terminal 22 and the second terminal 24 in the vertical direction. In this way, since the distance between the first terminal 22 and the second terminal 24 can be controlled by the film thickness of the insulating member 26, the insulating characteristics can be controlled more precisely. The first terminal 22 and the second terminal 24 may be arranged so as to partially overlap in a plan view. However, when the overlapping area increases, the first terminal 22 and the second terminal 24 become conductive due to a crack or the like of the insulating member 26. Therefore, it is preferable to arrange the tip of the first terminal 22 and the tip of the second terminal 24 so as to substantially coincide with each other. The distance between the tip of the first terminal 22 and the tip of the second terminal 24 in plan view is, for example, about 1 μm or less.

As the first terminal 22 and the second terminal 24, W, Ti / Rh / Au, or the like can be used. The materials of the first terminal 22 and the second terminal 24 may be the same as or different from those of the first electrode 16 and / or the second electrode 18. For example, when one of the first terminal 22 and the second terminal 24 is formed simultaneously with the first electrode 16 and the second electrode 18, only that terminal is formed of the same material as the first electrode 16 and the second electrode 18. The remaining terminals may be formed from different materials. Unlike the first electrode 16 and the second electrode 18, the first terminal 22 and the second terminal 24 do not need to be connected to a wire or the like. It is not necessary to provide it. For this reason, the 1st terminal 22 and the 2nd terminal 24 can be comprised with a single metal layer (for example, only W layer), and, thereby, material cost can be held down. In addition, the distance between the first terminal 22 and the second terminal 24 and the material of the insulating member 26 are such that the dielectric breakdown occurs faster than the active layer 12, the first conductive semiconductor layer 10, and the second conductive semiconductor layer 14 are destroyed. Set to be. Specifically, when a gallium nitride based semiconductor is used as the active layer 12, the first conductive type semiconductor layer 10, and the second conductive type semiconductor layer 14, SiO ₂ is used as the insulating member 26, and the first terminal 22 and The distance of the second terminal 24 is preferably about 10 nm to 500 nm. The material of the insulating member 26 may be an insulating material, and Al ₂ O ₃ or TiO ₂ can also be used. Also in the case of Al ₂ O ₃ or TiO ₂ , the distance between the first terminal 22 and the second terminal 24 can be about 10 nm to 500 nm.

  Since the discharge part 20 becomes a light-shielding part, the discharge part 20 is preferably small. Specifically, in plan view, the total area of the first terminal 22 and the second terminal 24 is preferably smaller than the area of the active layer 12, for example, about 1 to 2% of the area of the active layer 12. . In addition, a plurality of discharge units 20 can be provided in one light emitting element. However, the area of the light extraction surface is relatively reduced as the total area of the discharge unit 20 is increased, and thus only one discharge unit 20 is required. . However, in the case where a plurality of discharge portions 20 are provided, it is possible to provide a light emitting element that can withstand a plurality of reverse currents. This is because even if the reverse current flows once, only one discharge part 20 is used for discharge and destroyed, and the other discharge parts 20 are considered to remain without being destroyed. When a plurality of discharge units 20 are provided, at least one of the plurality is preferably configured and arranged as described in this embodiment, and all the discharge units 20 are configured and arranged as described in this embodiment. More preferably. That is, for example, it is preferable to arrange all the discharge portions 20 in a region other than between the first electrode 16 and the second electrode 18.

  The second electrode 18 usually includes a pad portion 18a. The pad portion 18a is a portion to which an external connection member such as a wire is connected. When the insulating protective film 34 is provided, an opening of the insulating protective film 34 is disposed on the upper surface of the pad portion 18a. Where current tends to flow in the region between the pad portion 18a and the first electrode 16 and the light emission intensity tends to increase, the discharge portion 20 (the first terminal 22 and the second terminal 24) has a high light emission intensity. Therefore, it is preferable to be disposed in a region other than between the first electrode 16 and the pad portion 18a. In this way, even if the first terminal 22 and the second terminal 24 are deteriorated or damaged, it is difficult to block light in a region having a high light emission intensity. Therefore, the installation of the discharge unit 20 is unlikely to cause a decrease in light emission efficiency. .

  When the second electrode 18 includes the pad portion 18a, the discharge portion 20 (more specifically, one of the first terminal 22 and the second terminal 24 closer to the first electrode 16 is not limited). The distance between the first electrode 16 and the first electrode 16 is the distance between the discharge portion 20 (more specifically, the first terminal 22 and the second terminal 24 closer to the pad portion 18a) and the pad portion 18a. Preferably longer than the distance. In this way, since the first terminal 22 and the second terminal 24 can be arranged avoiding the region with high emission intensity, it is possible to further suppress the decrease in light emission efficiency.

  In addition, when the second electrode 18 includes the pad portion 18a, the pad portion 18a is not particularly limited, but the pad portion 18a is connected to the discharge portion 20 (more specifically, the first terminal 22 and the second terminal 24). It is preferable that the first electrode 16 is disposed between the terminal closer to the first electrode 16 and the first electrode 16. In this way, since the first terminal 22 and the second terminal 24 can be arranged avoiding the region with high emission intensity, it is possible to further suppress the decrease in light emission efficiency.

  The second electrode 18 may have a translucent conductive layer 28 disposed on the second conductivity type semiconductor layer 14. In this case, a metal layer can be disposed on the translucent conductive layer 28, and part or all of the metal layer can be used as the pad portion 18a. In this case, the first terminal 22 and the second terminal 24 are preferably arranged in a region other than between the first electrode 16 and the metal layer. In this way, since the first terminal 22 and the second terminal 24 can be arranged avoiding the region with high emission intensity, it is possible to further suppress the decrease in light emission efficiency.

  The first electrode 16 also usually has a pad portion. When the first electrode 16 has a pad portion and a branch portion, the discharge portion 20 is preferably disposed in a region other than between the pad portion 18a of the first electrode 16 and the pad portion 18a of the second electrode. More preferably, it is disposed in a region other than between the entire first electrode 16 and the entire second electrode 18 including the branch portion. For example, it is an extension of a line connecting the pad portion of the first electrode 16 and the pad portion 18a of the second electrode 18, and is opposite to the pad portion of the first electrode 16 with the pad portion 18a of the second electrode 18 in between. The discharge part 20 can be arrange | positioned at the side. In this way, since the first terminal 22 and the second terminal 24 can be arranged avoiding the region with high emission intensity, it is possible to further suppress the decrease in light emission efficiency.

  Moreover, when the planar view shape of a light emitting element is a rectangle, you may arrange | position the discharge part 20 to the corner vicinity. In the case of a light-emitting element for face-up mounting as shown in FIGS. 1 and 2, light is extracted from the surface of the second conductivity type semiconductor layer 14, so that the formation position of the metal layer is limited to a part. Yes. On the other hand, in the case of a light-emitting element for face-down mounting, since there is no such limitation, the in-plane distribution of emission intensity tends to be smaller than that of the light-emitting element for face-up mounting, but in the vicinity of the outer edge of the light-emitting element. Since the light emission intensity tends to be relatively low, the discharge part 20 is preferably arranged in the vicinity of the outer edge of the light emitting element. In particular, when the planar view shape of the light emitting element is rectangular, it is preferable to dispose the discharge part 20 near the corner.

  According to the first embodiment described above, since the first terminal 22 is disposed separately from the first electrode 16 on the first conductive semiconductor layer 10, the active layer 12 caused by reverse electrostatic discharge (ESD), In addition to reducing the deterioration and damage of the first conductive type semiconductor layer 10 and the second conductive type semiconductor layer 14, the first electrode 16 and its peripheral parts are deteriorated or damaged by reverse electrostatic discharge (ESD). It can also be reduced. Therefore, it is possible to provide the light emitting element 1 that has high resistance to electrostatic discharge (ESD) in the reverse direction and can suppress a decrease in light emission efficiency.

(Other)
In addition, the light-emitting element 1 according to Embodiment 1 may include a sapphire substrate 32, an insulating protective film 34, and the like. As the insulating protective film 34, or the like can be used SiO _{2, Al} 2 _{O 3.} The insulating protective film 34 may be made of the same material as the insulating member 26. In this case, the first conductive semiconductor layer 10 or the second conductive semiconductor layer 14 (the first conductive semiconductor layer 10 in the present embodiment) is disposed on the sapphire substrate 32, for example. Instead of the sapphire substrate 32, a substrate made of other insulating or conductive material can be used. The insulating protective film 34 is provided so as to open a portion where an external connection member such as a wire is provided and to cover the other portions. That is, the insulating protective film 34 is provided so as to cover the side surfaces and surfaces of the first conductive semiconductor layer 10, the active layer 12, the second conductive semiconductor layer 14, the first electrode 16, and the second electrode 18, for example. It is done.

[Light-Emitting Element 2 According to Embodiment 2]
FIG. 3 is a schematic plan view of the light-emitting element according to Embodiment 2, and FIG. 4 is a cross-sectional view taken along the line BB in FIG. As illustrated in FIGS. 3 and 4, the light-emitting element 2 according to the second embodiment includes an insulating protective film 30 on the first conductive semiconductor layer 10, and the second terminal 24 and the insulating member 26 have insulating protection. The light emitting device 1 is different from the light emitting device 1 according to the first embodiment in that it is disposed on the film 30. In this way, even if the first terminal 22 and the second terminal 24 are deteriorated or damaged when the discharge function is activated by electrostatic discharge (ESD), the second terminal 24 and the first conductive semiconductor layer 10 Therefore, it is possible to suppress the occurrence of leakage due to the contact. As in FIG. 1, the insulating protective film 34 is omitted in FIG.

(Insulating protective film 30)
As the insulating protective film 30, or the like can be used SiO _{2, Al} 2 _{O 3.} The insulating protective film 30 may be made of the same material as the insulating protective film 34. When the same material is used, the insulating protective film 30 and the insulating protective film 34 can be manufactured in the same process. This has the effect of shortening the process and suppressing the increase in manufacturing cost. The insulating protective film 30 may be made of the same material as the insulating member 26.

[Light-Emitting Element 3 According to Embodiment 3]
FIG. 5 is a schematic plan view of the light-emitting element according to Embodiment 3, and FIG. 6 is a cross-sectional view taken along the line CC in FIG. As shown in FIGS. 5 and 6, in the light emitting element 3 according to the third embodiment, the second electrode 18 has a branch portion 18 b extending from the pad portion 18 a, and the first terminal 22 and the second terminal 24 are the pad portion. The light emitting element 2 is different from the light emitting element 2 according to the second embodiment in that it is disposed in a region other than the portion between the portion closer to the first electrode 16 and the first electrode 16 among the portion 18a and the branch portion 18b. In this case, in the case of having the branch portion 18b extending from the pad portion 18a, the first terminal 22 and the second terminal 24 can be arranged avoiding the region having a high emission intensity, thereby further suppressing the decrease in the light emission efficiency. be able to. Note that the pad portion 18 a and the branch portion 18 b disposed on the translucent conductive layer 28 are examples of a metal layer disposed on the translucent conductive layer 28. Further, the branch portion 18b is a portion extending from the pad portion 18a, and typically has a smaller width than the pad portion 18a as shown in FIG. As in FIG. 1, the insulating protective film 34 is omitted in FIG.

[Light-Emitting Element 4 According to Embodiment 4]
FIG. 7 is a schematic plan view of a light emitting device according to Embodiment 4, and FIG. 8 is a cross-sectional view taken along the line DD in FIG. As shown in FIGS. 7 and 8, the light-emitting element 4 according to Embodiment 4 has a substantially square shape in plan view, and the first electrode 16 has a branch portion 16b in addition to the pad portion 16a. It is different from the light emitting element 3 according to the third embodiment. Further, the pad portion 16 a and the pad portion 18 a are disposed on the diagonal line of the light emitting element 4. Thus, when the 1st electrode 16 also has the pad part 16a and the branch part 16b similarly to the 2nd electrode 18, the discharge part 20 should be arrange | positioned except the area | region between the pad part 16a and the pad part 18a. In addition, it is preferable to dispose the discharge portion 20 in a region other than the region between the first electrode 16 and the second electrode 18 including the pad portion 16a and the branch portion 16b. This is because the first terminal 22 and the second terminal 24 can be arranged avoiding a region having a high light emission intensity, so that a decrease in light emission efficiency can be further suppressed. In addition, when the planar view shape of the light emitting element 4 is a rectangle and the pad portion 16a of the first electrode 16 and the pad portion 18a of the second electrode 18 are disposed on the diagonal line, the pad portion 18a is disposed. Since the light emission intensity tends to be relatively low near the corner on the other side, it is preferable to dispose the discharge part 20 near the corner on the side where the pad portion 18a is disposed. As in FIG. 1, the insulating protective film 34 is omitted in FIG.

  While the embodiments have been described above, these descriptions are only examples, and do not limit the configurations described in the claims.

1, 2, 3, 4 Light emitting element 10 First conductive type semiconductor layer 12 Active layer 14 Second conductive type semiconductor layer 16 First electrode 16a Pad part 16b Branch part 18 Second electrode 18a Pad part 18b Branch part 20 Discharge part 22 First terminal 24 Second terminal 26 Insulating member 28 Translucent conductive layers 30 and 34 Insulating protective film 32 Sapphire substrate

Claims (8)

A first conductivity type semiconductor layer;
An active layer disposed on the first conductive semiconductor layer;
A second conductivity type semiconductor layer disposed on the active layer;
A first electrode disposed on the first conductive semiconductor layer;
A second electrode disposed on the second conductive semiconductor layer;
A discharge part,
The discharge part is
A first terminal electrically connected to the first conductive semiconductor layer and disposed separately from the first electrode on the first conductive semiconductor layer;
A second terminal electrically connected to the second conductivity type semiconductor layer;
An insulating member provided between the first terminal and the second terminal;
A light-emitting element comprising: The discharge part includes an insulating protective film on the first conductive semiconductor layer,
The second terminal and the insulating member are disposed on the insulating protective film;
The light-emitting element according to claim 1.   The light emitting device according to claim 1, wherein the insulating member is disposed so as to be sandwiched between the first terminal and the second terminal in a vertical direction. The second electrode includes a pad portion,
4. The light emitting device according to claim 1, wherein the discharge part is disposed in a region other than between the first electrode and the pad part. 5. The second electrode includes a branch portion extending from the pad portion,
The said discharge part is arrange | positioned in the area | regions other than between the part near the said 1st electrode among the said pad part and the said branch part, and the said 1st electrode. Light emitting element.   6. The light emitting device according to claim 4, wherein a distance between the discharge part and the first electrode is longer than a distance between the discharge part and the pad part.   The light emitting device according to claim 4, wherein the pad portion is disposed between the discharge portion and the first electrode. The first conductive semiconductor layer is an n-type semiconductor layer;
The second conductive semiconductor layer is a p-type semiconductor layer;
The light emitting device according to claim 1, wherein the light emitting device is a light emitting device.

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