WO2014126438A1

WO2014126438A1 - Semiconductor light-emitting element and production method therefor

Info

Publication number: WO2014126438A1
Application number: PCT/KR2014/001282
Authority: WO
Inventors: 하준석; 이인우
Original assignee: 전남대학교산학협력단
Priority date: 2013-02-18
Filing date: 2014-02-18
Publication date: 2014-08-21

Abstract

Disclosed are a semiconductor light-emitting element and a production method therefor. The semiconductor light-emitting element comprises: a light-emitting structure; an electrode structure which is disposed laminated on the lower-surface side of the light-emitting structure, and having an electrode electrically connected to a semiconductor layer of the light-emitting structure through a via hole; and a current-spreading layer formed on a semiconductor layer disposed on the upper part of the light-emitting structure. Because of the current-spreading layer, the number of via holes can be reduced and the light-emitting efficiency enhanced.

Description

Semiconductor light emitting device and manufacturing method thereof

The present invention relates to the field of semiconductor devices, and more particularly, to a semiconductor light emitting device and a method of manufacturing the same.

Currently, semiconductor light emitting devices such as LEDs are used in various lighting fixtures. A light emitting device is a semiconductor device in which light emission occurs when electrons and holes recombine at a junction portion of a p-type and n-type semiconductor.

The semiconductor light emitting device has a longer life and lower power consumption than conventional light emitting devices such as incandescent lamps.

Recently, research on group III nitride semiconductors and production of products using the same have been actively conducted. Such a group III nitride semiconductor has the advantage of being able to emit the light of the blue series that has been weak.

However, in the case of the group III nitride semiconductor, there is a disadvantage that it is grown on a specific substrate such as a sapphire substrate. In the case of an insulated substrate such as sapphire, there is a big limitation in the arrangement of electrodes when the light emitting device is manufactured horizontally. Therefore, a vertical light emitting device has been developed and used to arrange the electrode structure on the lower surface side of the light emitting structure and connect the electrode to the semiconductor layer of the light emitting structure through via holes.

4 and 5 show a conventional vertical semiconductor light emitting device, which is a sectional view taken along a plan view and a line B-B ', respectively.

The conventional vertical semiconductor light emitting device has a light emitting structure in which the n-GaN layer 110, the active layer 130, and the p-GaN layer 120 are stacked from above, and the bottom surface of the light emitting structure (p-GaN layer) as shown. The n-type electrode 210 is disposed on an outer surface of the 120 and includes an electrode structure electrically connected to the n-GaN layer through one or more via holes 310. In addition, the second electrode 220 of the electrode structure is stacked on the lower surface of the p-GaN layer 120 is electrically connected to the p-GaN (120) layer. Therefore, the via hole 310 for connecting the first electrode 210 exposes the n-GaN layer 110 through the second electrode 220, the p-GaN layer 120, and the active layer 130. Has The n-type electrode 210 is disposed in the via hole 310 to be electrically connected to the n-GaN layer 110. In addition, an insulating layer 230 is disposed between the second electrode 22 and the first electrode 21 and on the inner wall surface of the via hole 310 to insulate the first electrode 21 from other elements. The submounting substrate 250 bonded through the bonding layer 240 is disposed below.

In the semiconductor light emitting device according to the related art as described above, since the n-type electrode 210 and the n-GaN layer 110 are connected through the plurality of via holes 310, a large number of via holes 310 are disposed. Otherwise, as can be seen in FIG. 4, the region with a small current distribution is enlarged. In addition, it is not easy to form the plurality of via holes 310 in the micro process, and the entire light emitting area has to be reduced since the active layer 130 is lost as much as the via holes 310.

(Prior art document)

(Patent literature)

Korean Patent Publication 10-2010-0054756

The present invention provides a semiconductor light emitting device having an improved current spreading effect by forming a current spreading layer on an upper surface of a semiconductor layer as a light emitting device in which an electrode and a semiconductor layer of the light emitting structure are connected through at least one via hole formed in the light emitting structure.

The present invention provides a semiconductor light emitting device in which the number of via holes is reduced by increasing the current spreading effect by the current spreading layer.

The present invention provides a semiconductor light emitting device in which the amount of light emitted is increased and the series resistance is reduced by reducing the thickness of the semiconductor layer disposed on the light emitting structure.

The present invention provides a method of manufacturing the above-described improved semiconductor light emitting device.

The present invention provides a semiconductor light emitting device comprising: a light emitting structure comprising a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer sequentially stacked from above; An electrode structure stacked on the lower surface of the second conductive semiconductor layer in the light emitting structure; And a current spreading layer formed on the first conductive semiconductor layer.

The electrode structure may include a second electrode stacked on a lower surface of the second conductive semiconductor layer and at least one via hole penetrating through the second electrode, the second conductive semiconductor layer, and the active layer. A first electrode electrically connected to the semiconductor layer, and an insulating film insulating the first electrode from the second electrode, the second conductive semiconductor layer, and the active layer.

The second electrode may be a light reflection layer.

The second electrode has an exposed portion in which the current spreading layer, the first conductive semiconductor layer, the active layer, and the second conductive semiconductor layer are partially removed, and an electrode pad is disposed on the exposed portion. .

The current spreading layer may be formed of a conductive material, and the current spreading layer may be formed of any one of a transparent conductive oxide (TCO), graphene, gold, tungsten, indium, and nickel.

The first conductive semiconductor layer may have a thickness of 0.3 to 0.5 μm.

The semiconductor light emitting device of the present invention comprises: a light emitting structure in which an n-type semiconductor layer, an active layer, and a p-type semiconductor layer are sequentially stacked from above; A p-type electrode disposed on a lower surface of the p-type semiconductor layer in the light emitting structure and electrically connected to the p-type semiconductor layer; An n-type electrode electrically connected to the n-type semiconductor layer through at least one via hole passing through the p-type electrode, the p-type semiconductor layer, and the active layer; And an insulating film insulating the n-type electrode from the p-type electrode, the p-type semiconductor layer, and the active layer. A current spreading layer made of a conductive material is disposed on the n-type semiconductor layer.

The p-type electrode has an exposed portion by partially removing the current spreading layer, the n-type semiconductor layer, the active layer, and the p-type semiconductor layer, and an electrode pad is formed on the exposed portion.

The n-type semiconductor layer may have a thickness of 0.3 to 0.5㎛.

The present invention provides a method for manufacturing a semiconductor light emitting device, the method comprising: preparing a growth base layer; Forming a light emitting structure by sequentially stacking a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer on the growth base layer; Forming an electrode structure including a first electrode and a second electrode on the second conductive semiconductor layer; Removing the growth base layer to expose the first conductive semiconductor layer; And forming a current spreading layer on an exposed surface of the first conductive semiconductor layer.

The forming of the electrode structure may include: forming a second electrode on the second conductive semiconductor layer; Forming at least one via hole through the second electrode, the second conductive semiconductor layer, and the active layer to expose the first conductive semiconductor layer; Forming an insulating film on an upper surface of the second electrode and an inner wall surface of the at least one via hole; And forming a first electrode electrically connected to the first conductive semiconductor layer through the one or more via holes.

The growth base layer is removed to further remove the exposed surface of the first conductive semiconductor layer to a predetermined thickness.

After the surface is removed, the first conductive semiconductor layer may have a thickness of 0.3 μm to 0.5 μm.

The first conductive semiconductor layer and the second conductive semiconductor layer are n-GaN doped with n-type impurities and p-GaN doped with p-type impurities, respectively.

The growth base layer may include sapphire substrate and u-GaN which is not doped with impurities.

In addition, the manufacturing method of the present invention after forming the exposed portion of the second electrode by partially removing the current spreading layer, the first conductive semiconductor layer, the active layer, and the second conductive semiconductor layer. The method may further include forming an electrode pad at the site.

According to the present invention, a light emitting device in which an electrode and a semiconductor layer are connected through a via hole formed in a light emitting structure is provided. The semiconductor light emitting device can reduce the number of via holes by increasing the current spreading effect by the current spreading layer, and also facilitate the manufacturing process. As a result, process stability and reliability are increased. In addition, the present invention can provide a high quality light emitting device by reducing the amount of light emitted and the series resistance is reduced by reducing the thickness of the semiconductor layer disposed on the light emitting structure.

1 is a plan view schematically showing a semiconductor light emitting device according to a preferred embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along line AA ′ of FIG. 1.

3A to 3I are cross-sectional views illustrating a method of manufacturing a semiconductor light emitting device according to a preferred embodiment of the present invention.

4 and 5 show a conventional semiconductor light emitting device, which is a sectional view taken along a plan view and a line B-B ', respectively.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing the embodiments of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

1 is a plan view schematically showing a light emitting device according to a preferred embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line AA ′ of FIG. 1.

1 and 2, a semiconductor light emitting device according to a preferred embodiment of the present invention includes a semiconductor layer in which an electrode disposed on one side of a light emitting structure is positioned on the light emitting structure through a via hole passing through a portion of the light emitting structure. Corresponds to the so-called vertical light emitting device electrically connected to the.

The semiconductor light emitting device according to the preferred embodiment of the present invention includes a light emitting structure 1, an electrode structure 2 disposed on the lower surface side thereof, and a current spreading layer 41 formed on the upper surface of the light emitting structure 1. Include.

The light emitting structure 1 includes a first conductive semiconductor layer 11, an active layer 13, and a second conductive semiconductor layer 12 sequentially stacked from above. For reference, the "sequential lamination from the top" as used herein is not laminated from the top to the bottom in the actual manufacturing process, it is to reverse the substrate in the middle of the manufacturing process. As described below in the manufacturing method of the present invention, the first conductive semiconductor layer 11 is first stacked on the growth base layer, and then the active layer 13 and the second conductive semiconductor layer 12 are sequentially stacked. Subsequently, after the substrate is stacked up to the submounting substrate 25, the substrate is inverted to perform the remaining process.

The electrode structure 2 is disposed on the outer surface (lower surface) of the second conductive semiconductor layer 12, and the second electrode 22 and the insulating film sequentially stacked from the second conductive semiconductor layer 12 side. 23, and a first electrode 21. The electrode structure 2 may include a bonding layer 24 formed on the bottom surface of the first electrode 21 and a conductive submounting substrate 25.

Specifically, the second electrode 22 of the electrode structure 2 is stacked on the outer surface of the second conductive semiconductor layer 12 and electrically connected to the second conductive semiconductor layer 12. The second electrode 22 may serve as a reflective layer.

The semiconductor light emitting device according to the preferred embodiment of the present invention includes a second electrode 22, a second conductive semiconductor layer 12, and one or more via holes 31 penetrating through the active layer 13. An insulating film 23 is formed on the outer surface of the second electrode 22 and the inner wall surface of the via hole 31.

The first electrode 21 is electrically connected to the first conductive semiconductor layer 11 through the via hole 31. As illustrated, the first electrode 21 is electrically insulated from the second electrode 22 and the active layer 13 by the insulating film 23.

Preferably, the via hole 31 extends to the inside of the first conductive semiconductor layer 11, so that the first electrode 21 is aligned with the first conductive semiconductor layer 11 in the first conductive semiconductor layer 11. Can be electrically connected.

In the semiconductor light emitting device of the present invention, as described above, the second electrode 22 is a reflective layer, or an additional reflective layer (not shown) further interposed between the second electrode 22 and the second conductive semiconductor layer 12. As a result, the light of the light emitting structure 1 is reflected toward the first conductive semiconductor layer 11.

A bonding layer 24 electrically connected to the first electrode 21 may be provided on the outer surface (lower surface) of the insulating layer 23. The submounting substrate 25 is provided on the outer surface of the bonding layer 24.

The semiconductor light emitting device of the preferred embodiment of the present invention includes a current spreading layer 41 formed on the outer surface (upper surface) of the first conductive semiconductor layer 11. The current spreading layer 41 may be formed of a conductive material, and preferably, may be formed of any one of a transparent current oxide (TCO), graphene, gold, tungsten, indium, and nickel.

More preferably, the surface of the first conductive semiconductor layer 11 may be removed to a predetermined depth before forming the current spreading layer 41. In this case, the first conductive semiconductor layer 11 may have a thickness of 0.3 μm to 0.5 μm.

Also, preferably, the second electrode 22 is partially exposed by exposing the current spreading layer 41, the first conductive semiconductor layer 11, the active layer 13, and the second conductive semiconductor layer 12. Has an exposed portion 221. The electrode pad 222 is formed on the exposed portion 221 so that the wire 223 may be connected.

In the semiconductor light emitting device according to the preferred embodiment of the present invention, the first conductive semiconductor layer 11 may be, for example, an n-type nitride semiconductor such as n-GaN, and the second conductive semiconductor layer 12 may be, for example, p−. P-type nitride semiconductor such as GaN.

The material for the active layer 13 may be selected according to the first and second conductive semiconductor layers 11 and 12. For example, the active layer 13 may be formed of a material having an energy band gap less than that of the first and second conductive semiconductor layers 11 and 12.

In the semiconductor light emitting device according to the preferred embodiment of the present invention, since the current spreading layer 41 is disposed on the first conductive semiconductor layer 11, the current spreading effect is increased and the series resistance is lowered. Furthermore, the number of via holes 31 for the first electrode 21 can be reduced due to the current spreading layer 41. This is because the active layer 13 is less reduced, so that the light emitting area increases. In addition, in the semiconductor light emitting device according to the preferred embodiment of the present invention, since the first conductive semiconductor layer 11 is thinner than the conventional one, the amount of light emitted is increased.

Hereinafter, a method of manufacturing a semiconductor light emitting device will be described with reference to FIGS. 3A to 3I.

First, the growth base layer 50 is prepared. The growth base layer 50 may include, for example, a sapphire substrate 51 and a u-GaN layer 52 which is not doped with impurities grown thereon.

As shown in FIG. 3A, the light emitting structure 1 is formed on the u-GaN layer 52 of the growth base layer 50.

For example, the light emitting structure 1 may be formed by sequentially forming the first conductive semiconductor layer 11, the active layer 13, and the second conductive semiconductor layer 12 on the u-GaN layer 52. do. The first conductive semiconductor layer 11 may be an n-GaN layer, and the second conductive semiconductor layer 12 may be a p-GaN layer.

Next, the electrode structure 2 is formed on the light emitting structure 1 as shown in FIGS. 3b to 3d.

For example, after the second electrode 22 is formed on the second conductive semiconductor layer 12 (FIG. 3B), the second electrode 22 and the second conductive semiconductor layer are formed through photolithography and etching processes. (12) and the active layer 13 are partially removed to form a via hole 31 exposing the first conductive semiconductor layer 11.

In this case, preferably, the via hole 31 is extended to the inside of the first conductive semiconductor layer 11, so that the first electrode 21 may be formed within the first conductive semiconductor layer 11 as described below. It may be electrically connected to the conductive semiconductor layer 11. As such, the via hole 31 reaches the inside of the first conductive semiconductor layer 11 so that the first electrode 21 is more secure than the other layers other than the first conductive semiconductor layer 11 as described below. Can be insulated.

Subsequently, after forming the insulating film 23 on the second electrode 22 and reaching the inner wall surface of the via hole 31 (FIG. 3C), the first electrode 21 is formed in the via hole 31 (FIG. 3D). ). The first electrode 21 thus formed is electrically connected to the first conductive semiconductor layer 11 at the bottom of each via hole 31 and electrically insulated from the remaining layers.

Next, the conductive submounting substrate 25 is bonded through the bonding layer 24 (FIG. 3E). The bonding layer 24 is formed on the insulating film 23 and the first electrode 21 to form a first metal layer electrically connected to the first electrode 21, and a second metal layer and a second metal layer formed on the submounting substrate 25. The solder layer may be interposed between the first and second metal layers. This is because the first metal layer is formed on the insulating film 23 and the first electrode 21, and then sequentially stacked on the solder layer and the second metal layer submounting substrate 25 to bond the solder layer and the first metal layer. It can be implemented in a way.

Next, the growth base layer 50 is removed. Specifically, the sapphire substrate 51 is removed by, for example, laser lift-off (FIG. 3F), and the u-GaN layer 52 is removed by etching (FIG. 3F). At this time, the surface of the first conductive semiconductor layer 11 is further removed to a predetermined depth, preferably, etched to a distance close to the via hole 31 (FIG. 3G). For example, as shown in FIG. 3G, the first conductive semiconductor layer 11 left after the surface is removed to a predetermined depth may be 0.3 to 0.5 μm.

Subsequently, as shown in FIG. 3I, portions of the current spreading layer 41, the first conductive semiconductor layer 11, the active layer 13, and the second conductive semiconductor layer 12 are removed and partially exposed. The exposed portion 221 of the second electrode 22 is formed. Next, the electrode pad 222 and the wire 223 are connected to the exposed portion 221.

In the foregoing detailed description of the present invention, specific embodiments have been described. However, it will be apparent to those skilled in the art that various modifications can be made without departing from the scope of the present invention.

(Explanation of the sign)

1: light emitting structure 2: electrode structure

11: first conductive semiconductor layer 12: second conductive semiconductor layer

13: active layer 21: first electrode

22: second electrode 23: insulating film

24: bonding layer 25: submounting substrate

31: via hole 41: current spreading layer

50: growth base 51: sapphire substrate

52: u-GaN layer 221: exposed part

222: electrode pad 223: wire

Claims

A light emitting structure including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer sequentially stacked from above;

An electrode structure stacked on the lower surface of the second conductive semiconductor layer in the light emitting structure; And

And a current spreading layer formed on the first conductive semiconductor layer.
The method according to claim 1, wherein the electrode structure,

A second electrode stacked on a lower surface of the second conductive semiconductor layer,

A first electrode electrically connected to the first conductive semiconductor layer through at least one via hole penetrating through the second electrode, the second conductive semiconductor layer, and the active layer;

And an insulating film which insulates the first electrode from the second electrode, the second conductive semiconductor layer, and the active layer.
The method according to claim 2,

The second electrode is a light reflecting layer, semiconductor light emitting device.
The method according to claim 3,

The second electrode has an exposed portion exposed by partially removing the current spreading layer, the first conductive semiconductor layer, the active layer, and the second conductive semiconductor layer.

An electrode pad is disposed on the exposed portion, the semiconductor light emitting device.
The method according to claim 1,

The current spreading layer is formed of a conductive material, semiconductor light emitting device.
The method according to claim 5,

The current spreading layer is formed of any one of a transparent conductive oxide (TCO), graphene, gold, tungsten, indium, nickel, semiconductor light emitting device.
The method according to claim 1,

The first conductive semiconductor layer has a thickness of 0.3 to 0.5㎛, semiconductor light emitting device.
A light emitting structure in which an n-type semiconductor layer, an active layer, and a p-type semiconductor layer are sequentially stacked from above;

A p-type electrode disposed on a lower surface of the p-type semiconductor layer in the light emitting structure and electrically connected to the p-type semiconductor layer;

An n-type electrode electrically connected to the n-type semiconductor layer through at least one via hole passing through the p-type electrode, the p-type semiconductor layer, and the active layer; And

And an insulating film insulating the n-type electrode from the p-type electrode, the p-type semiconductor layer, and the active layer.

The current spreading layer made of a conductive material is disposed on the n-type semiconductor layer upper surface, the semiconductor light emitting device.
The method according to claim 8,

The p-type electrode has an exposed portion exposed by partially removing the current spreading layer, the n-type semiconductor layer, the active layer, and the p-type semiconductor layer,

Electrode pad is formed on the exposed portion, the semiconductor light emitting device.
The method according to claim 8,

The n-type semiconductor layer is a semiconductor light emitting device having a thickness of 0.3 to 0.5㎛.
As a method of manufacturing a semiconductor light emitting device:

Preparing a growth base layer;

Forming a light emitting structure by sequentially stacking a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer on the growth base layer;

Forming an electrode structure including a first electrode and a second electrode on the second conductive semiconductor layer;

Removing the growth base layer to expose the first conductive semiconductor layer; And

And forming a current spreading layer on the exposed surface of the first conductive semiconductor layer.
The method of claim 11, wherein the forming of the electrode structure comprises:

Forming a second electrode on the second conductive semiconductor layer;

Forming at least one via hole through the second electrode, the second conductive semiconductor layer, and the active layer to expose the first conductive semiconductor layer;

Forming an insulating film on an upper surface of the second electrode and an inner wall surface of the at least one via hole; And

And forming a first electrode electrically connected to the first conductive semiconductor layer through the one or more via holes.
The method according to claim 11,

And removing the surface of the first conductive semiconductor layer exposed by removing the growth base layer to a predetermined thickness.
The method according to claim 13,

After the surface is removed, the first conductive semiconductor layer has a thickness of 0.3 to 0.5㎛, a semiconductor light emitting device manufacturing method.
The method according to claim 14,

And the first conductive semiconductor layer and the second conductive semiconductor layer are n-GaN doped with n-type impurities and p-GaN doped with p-type impurities, respectively.
The method according to claim 13,

The growth base layer is a semiconductor light emitting device manufacturing method comprising a sapphire substrate and u-GaN doped with impurities.
The method according to claim 13,

Forming an exposed portion of the second electrode by partially removing the current spreading layer, the first conductive semiconductor layer, the active layer, and the second conductive semiconductor layer, and then forming an electrode pad on the exposed portion The method of manufacturing a semiconductor light emitting device further comprising.