KR101393355B1 - Light emitting diode and method of fabricating the same - Google Patents

Abstract

The present invention relates to a support substrate; Metal layers that are spaced apart from each other on the support substrate and include a metal reflection layer and a metal-mediate layer; Light emitting cells located on a part of the metal layers and including a first conductivity type semiconductor layer, an active layer and a second conductivity type semiconductor layer, respectively; And metal wires for supplying power to the upper part of the light emitting cells and the upper part of the metal reflection layer, wherein the light emitting cells are formed in a region of the semiconductor layers irradiated with the laser by the laser lift- And the light emitting cells are partially or wholly removed, so that the light emitting cells are spaced apart from each other.

Light emitting diode, LED, sapphire, parallel, ac, light emitting cell

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode and a method of manufacturing the same, and more particularly, to a light emitting diode manufactured by performing a LLO (laser lift-off) process and a method of manufacturing the same.

A light emitting diode (LED) is a structure in which a GaN-based material is grown on a substrate such as GaN, sapphire, silicon, or silicon nitride to emit light. In this structure, the light emitted from the upper light emitting layer travels to the upper and lower portions, and is emitted to the outside of the light emitting diode through reflection, scattering, and refraction. In order to increase the luminous efficiency by refracting and reflecting the light from the upper and lower portions coming from the light emitting layer, it is necessary to use a reflective substrate having an irregularity on the top or a reflectivity on the bottom.

However, the upper P layer of the light emitting layer is thin, so that it can not be provided with concave and convex portions, or the efficiency is small even if irregularities are generated. Even if a metal material with a good reflectance is deposited under the sapphire substrate at the bottom, light that is absorbed and destroyed by the sapphire itself always exists. As such, the light emitted to the bottom is emitted through the substrate, and the loss when passing through the substrate is large. In order to reduce the loss, it is necessary to use a laser lift-off (LLO) process to avoid the absorption at the surface of the substrate and to increase the reflection or to use a metal having a high reflectivity on the substrate. And a Si substrate or a metal substrate was added.

In the case of using the LLO process, it is difficult to obtain a uniform intensity within the irradiation area because the area for irradiating the laser is small. Therefore, when the portion irradiated with the laser is used as the light emitting cell, the light efficiency of the light emitting cells is not uniform.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a light emitting diode and a method of manufacturing the same.

According to an aspect of the present invention, there is provided a semiconductor device comprising: a support substrate; Metal layers that are spaced apart from each other on the support substrate and include a metal reflection layer and a metal-mediate layer; Light emitting cells located on a part of the metal layers and including a first conductivity type semiconductor layer, an active layer and a second conductivity type semiconductor layer, respectively; And metal wires for supplying power to the upper part of the light emitting cells and the upper part of the metal reflection layer, wherein the light emitting cells are formed in a region of the semiconductor layers irradiated with the laser by the laser lift- And the light emitting cells are partially or wholly removed, so that the light emitting cells are spaced apart from each other.

Preferably, the light emitting cells include a part or all of the regions irradiated with the laser by the laser lift-off process in the semiconductor layers, and a part of the semiconductor layer in the vertical direction of the part or the whole The light emitting cells are formed in a net shape.

Preferably, the supporting substrate is a substrate of the same type as the growth substrate used for growing the semiconductor layers.

Preferably, the supporting substrate is a sapphire substrate.

According to another aspect of the present invention, there is provided a light emitting device including: a semiconductor substrate including a buffer layer, a first conductivity type semiconductor layer, an active layer and a second conductivity type semiconductor layer on a first substrate and a metal reflection layer on the semiconductor layers, Forming a first metal-mediated layer on the metal reflective layer, forming a second metal-mediated layer on the second substrate, bonding the metal-mediated layers such that the first metal-mediated layer and the second metal- Separating the first substrate from the semiconductor layers through a laser lift-off process, patterning the semiconductor layers so that the metal reflection layer is exposed, forming light emitting cells spaced apart from each other and positioned on the metal reflection layer, Forming metal wires for supplying power to the upper surface of the light emitting cells and the upper portion of the metal reflection layer, And the light emitting cells are spaced apart from each other by removing a part or all of the regions irradiated with the laser by the laser lift-off process in the body layers.

Preferably, the step of forming the light emitting cells includes a part or all of the regions irradiated with the laser by the laser lift-off process in the semiconductor layers, The light emitting cells are formed in a net shape by removing a region including a part of the layer.

According to another aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: forming a semiconductor layer including a buffer layer, a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer on a first substrate; , Separating the first substrate from the semiconductor layers through a laser lift-off process, patterning the semiconductor layers to form light emitting cells spaced apart from each other, forming the light emitting cells into metal wirings, Wherein the forming of the light emitting cells is performed by removing a part or all of the regions irradiated with the laser by the laser lift-off process in the semiconductor layers, thereby forming the light emitting cells apart from each other do.

Preferably, the step of forming the light emitting cells includes a part or all of the regions irradiated with the laser by the laser lift-off process in the semiconductor layers, The light emitting cells are formed in a net shape by removing a region including a part of the layer.

According to the present invention, when the light emitting diode is manufactured by removing the growth substrate through the LLO process, the overlapping portions of the light emitting cells are removed by the LLO process to separate the light emitting cells, A large area light emitting diode having uniform light efficiency as a whole can be manufactured.

According to the present invention, when the light emitting diode is manufactured by removing the growth substrate through the LLO process, the metal layers including the metal reflection layer are formed on the support substrate, and the light emitting cells are formed on the metal layers, Therefore, it is more effective than diffusing a current by arranging a simple branch in a conventional large area light emitting diode.

According to the present invention, the metal reflective layer exposed between the unit cells serves as a reflective layer of light emitted from the light emitting layer to the lower portion, thereby increasing the light efficiency.

In addition, according to the present invention, light emitted from a light emitting layer does not exit through sapphire as in a conventional large-area sapphire, but is reflected by a metal reflection layer on a sapphire, And can be evenly distributed.

According to the present invention, when a light emitting diode is manufactured by removing a growth substrate through an LLO process, a substrate having the same thermal expansion coefficient as that of the growth substrate is used as the support substrate, so that after bonding the semiconductor layers and the substrate It is possible to effectively prevent the deformation occurring in the bonding process of the high pressure and high pressure for the light emitting diode, thereby increasing the production yield of the light emitting diode and improving the light emitting property.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the embodiments described below, but may be embodied in other forms. In the drawings, the width, length, thickness, and the like of the components may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

1 is a cross-sectional view illustrating a light emitting diode according to an embodiment of the present invention.

Referring to FIG. 1, a plurality of metal patterns 40 are spaced apart from each other on a support substrate 51. The support substrate 51 may include a sapphire substrate, AlN, and GaN. The supporting substrate 51 uses a substrate of the same type as the substrate for growing the semiconductor layers constituting the light emitting cells 30. [ In this embodiment, the support substrate 51 is a sapphire substrate which is an insulating substrate.

Each of the metal patterns 40 includes bonded metal layers such as a metal reflective layer 31, a metal protective layer 32, a first metal intermediate layer 33 and a second metal intermediate layer 53. The metal reflection layer 31 is formed of a metal material having a high reflectance such as silver (Ag) or aluminum (Al). The metal protection layer 32 is a diffusion preventing layer for preventing metal elements from diffusing into the metal reflection layer 31, and can maintain the reflectivity of the metal reflection layer 31. The first metal-mediating layer 33 and the second metal-mediating layer 53 are for bonding the metal reflection layer 31 and the support substrate 51 and may be Au or an alloy of Au and Sn, for example.

The light emitting cells 30 are positioned on a part of the metal pattern. The light emitting cell 30 includes a P-type semiconductor layer 29a, an active layer 27a, and an N-type semiconductor layer 25a. The active layer 27a is interposed between the P-type semiconductor layer 29a and the N-type semiconductor layer 25a and the P-type semiconductor layer 29a and the N-type semiconductor layer 25a can be displaced from each other.

The N-type semiconductor layer 25a may be formed of N-type Al _x In _y Ga _{1 -x- y} N (0? X, y, x + y? 1) and may include an N-type cladding layer. The P-type semiconductor layer 29a may be formed of P-type Al _x In _y Ga _{1 -xy} N (0? X, y, x + y? 1) and may include a P-type clad layer. The N-type semiconductor layer 25a may be doped with Si and the P-type semiconductor layer 29a may be doped with Zn or Mg.

The active layer 27a is a region where electrons and holes are recombined, and includes InGaN. The light emission wavelength emitted from the light emitting cell is determined according to the type of the material forming the active layer 27a. The active layer 27a may be a multi-layered film in which a quantum well layer and a barrier layer are repeatedly formed. The barrier layer and the well layer may be two-membered to quaternary compound semiconductor layers represented by the general formula Al _x In _y Ga _{1 -x- y} N (0? X, y, x + y? 1).

On the other hand, the metal wires 57 electrically connect the N-type semiconductor layer 25a and are connected to an external power supply lead. For this, an electrode pad 55 may be formed on each of the N-type semiconductor layers 25a. The electrode pad 55 is in ohmic contact with the N-type semiconductor layer 25a to lower the contact resistance. In addition, the metal wiring 58 is connected to the metal reflection layer 31 and connected to an external power supply lead. Therefore, the metal wires 57 and the metal wires 58 connect the light emitting cells 30 in a parallel array, as shown in the figure. Two or more arrays of light emitting cells connected in parallel may be formed on the substrate 51.

FIGS. 2 to 6 are cross-sectional views illustrating a method of fabricating a light emitting diode according to an embodiment of the present invention.

2, semiconductor layers including a buffer layer 23, an N-type semiconductor layer 25, an active layer 27, and a P-type semiconductor layer 29 are formed on a first substrate 21, A metal reflection layer 31 is formed on the layers.

Like the sapphire substrate, the first substrate 21 is light-transmissive, and a substrate that lattice-matches the semiconductor layers is advantageous.

The buffer layer 23 and the semiconductor layers 25, 27 and 29 may be formed using metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), or hydride vapor phase epitaxy (HVPE). Further, the semiconductor layers 25, 27, 29 may be formed continuously in the same process chamber.

The buffer layer 23 is not particularly limited as long as it can relax the lattice mismatch between the first substrate 21 and the semiconductor layers 25, 27 and 29, and may be formed of, for example, undoped GaN.

The metal reflective layer 31 is formed of a metal that is in ohmic contact with the P-type semiconductor layer and is preferably a metal having high reflectivity, and may be formed of Ag or Al, for example. In addition, the thermally conductive metal layer is preferably a metal having a high thermal conductivity, for example, Au or Au and Sn. A metal protection layer 32 is formed on the metal reflection layer 31. The metal protective layer 32 serves as a diffusion preventing layer. A first metal-mediated layer (33) is formed on the metal protective layer (32). The first metal-mediated layer 33 is not particularly limited and may be Au or a laminate of Au and Sn for metal bonding.

A second metal-mediated layer (53) is formed on a second substrate (51) separate from the first substrate (21). The second substrate 51 uses the same substrate as the first substrate 21.

The second metal-mediated layer 53 is for metal bonding with the first metal-mediating layer 31, and is not particularly limited, and Au or Au and Sn may be laminated.

Referring to FIG. 3, the first metal-mediated layer 33 and the second metal layer 53 are bonded so as to face each other. Such bonding can be easily performed by applying a certain pressure and / or heat.

Then, a laser beam is irradiated from the first substrate 21 side. At this time, the irradiation of the laser has a width L1 as shown in the drawing, and there is a portion overlapping each other. The laser may be, for example, a KrF (248 nm) laser. Since the first substrate 21 is a translucent substrate like a sapphire substrate, the laser passes through the first substrate 21 and is absorbed by the buffer layer 23. The buffer layer 23 is decomposed by the absorbed radiant energy at the interface between the buffer layer 23 and the first substrate 21 so that the substrate 21 is separated from the semiconductor layers do.

Referring to FIG. 4, after the substrate 21 is separated, the remaining buffer layer 23 is removed to expose the surface of the N-type semiconductor layer 25. The buffer layer 23 may be removed using an etching technique or a polishing technique.

Referring to FIG. 5, the semiconductor layers 25, 27 and 29 are patterned using a photolithography and etching technique to expose the metal reflection layer 31 to be spaced apart from the metal reflection layer 31 Emitting cell 30 is formed.

At this time, when patterning the semiconductor layers 25, 27 and 29 to separate the light emitting cells 30, the semiconductor layers 25, 27 and 29 are subjected to a laser lift-off process The light emitting cells 30a and 30b are formed so as to be spaced apart by removing a part or all of the overlapped and irradiated region L3. Further, as shown in FIG. 8, the semiconductor layers 25, 26, 27 include a part or all of the regions irradiated with the laser by the laser lift-off process, The light emitting cells 30c, 30d, 30e, and 30f may be formed in a net shape by removing a part of the layer.

The light emitting cell 30 includes a patterned P-type semiconductor layer 29a, an active layer 27a, and an N-type semiconductor layer 25a. These semiconductor layers 25a, 27a, 29a can be patterned in the same shape. Each of the light emitting cells 30 can be electrically connected through the metal reflection layer 31, the metal protection layer 32, the first metal intermediate layer 33, and the second metal intermediate layer 53, .

Referring to FIG. 6, a metal wiring 57 for electrically connecting upper surfaces of the light emitting cells 30 and a metal wiring 58 for supplying power to the metal reflection layer 31 are formed. The metal wires 57 and 58 connect the light emitting cells 30 in parallel to form an array of light emitting cells. More than two such arrays may be formed.

Meanwhile, the electrode pads 55 may be formed on the N-type semiconductor layer 25a before forming the metal wirings. The electrode pad 55 is in ohmic contact with the N-type semiconductor layer 25a.

According to this embodiment, as the metal reflection layer 31 is formed, the process of forming an additional electrode pad on the P-type semiconductor layer 29a is omitted.

Meanwhile, in the present embodiment, the P-type semiconductor layer 29 and the N-type semiconductor layer 25 may be formed in a different order from each other. In this case, a transparent electrode may be formed on the P-type semiconductor layer 29 after the buffer layer 23 is removed.

The invention being thus described, it will be obvious that the same way may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention as defined by the appended claims.

For example, in one embodiment of the present invention, a substrate of the same type as the growth substrate is used as the supporting substrate, but the present invention is not limited thereto. In addition, in the embodiment of the present invention, the shape of the air bridge is shown by the metal wiring connecting the light emitting cells, but it can be realized any way through the step cover process.

1 is a cross-sectional view illustrating a light emitting diode according to an embodiment of the present invention.

FIGS. 2 to 6 are cross-sectional views illustrating a method of fabricating a light emitting diode according to an embodiment of the present invention.

7 to 8 are plan views illustrating a light emitting diode according to an embodiment of the present invention.

Claims (10)

A support substrate; Metal layers that are spaced apart from each other on the support substrate and include a metal reflection layer and a metal-mediate layer; Light emitting cells located on a part of the metal layers and having semiconductor layers each including a first conductive type semiconductor layer, an active layer and a second conductive type semiconductor layer; And And metal wires for supplying power to an upper portion of the light emitting cells and an upper portion of the metal reflection layer, The light- Wherein the semiconductor layers are formed such that a part or all of the regions irradiated with the laser overlapping by the laser lift-off process are removed and are spaced apart from each other. The method according to claim 1, The light- The semiconductor layers include a part or all of the regions irradiated with the laser by the laser lift-off process, and a region including a part of the semiconductor layers in the vertical direction of the part or all is removed, And the light emitting diode is formed in a substantially flat shape. The method according to claim 1, Wherein the supporting substrate is a substrate of the same type as the growth substrate used for growing the semiconductor layers. The method according to claim 1, Wherein the supporting substrate is a sapphire substrate. A semiconductor layer including a buffer layer, a first conductivity type semiconductor layer, an active layer and a second conductivity type semiconductor layer on a first substrate, and a metal reflection layer on the semiconductor layers, Forming a first metal-mediated layer on the metal reflective layer, Forming a second metal-mediated layer on the second substrate, Wherein the metal-mediating layers are bonded such that the first metal-mediating layer and the second metal-mediating layer face each other, Separating the first substrate from the semiconductor layers through a laser lift-off process, Patterning the semiconductor layers so as to expose the metal reflection layer to form light emitting cells spaced apart from each other and located on the metal reflection layer, Metal wires for supplying power to the upper surface of the light emitting cells and the upper portion of the metal reflection layer are formed, The forming of the light emitting cells includes: Wherein the light emitting cells are spaced apart by removing a part or all of the regions irradiated with the laser by the laser lift-off process in the semiconductor layers. The method of claim 5, The forming of the light emitting cells includes: The semiconductor layer including a part or all of the regions irradiated with the laser by the laser lift-off process and removing a region including a part of the semiconductor layers in the vertical direction of the part or the whole, Are spaced apart in a net shape. Forming a semiconductor layer including a buffer layer, a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer on a first substrate, Bonding the second substrate to the semiconductor layers, Separating the first substrate from the semiconductor layers through a laser lift-off process, Patterning the semiconductor layers to form light emitting cells spaced apart from each other, Forming metal wires in the light emitting cells, The forming of the light emitting cells includes: Wherein the light emitting cells are spaced apart by removing a part or all of the regions irradiated with the laser by the laser lift-off process in the semiconductor layers. The method of claim 7, The forming of the light emitting cells includes: The semiconductor layer including a part or all of the regions irradiated with the laser by the laser lift-off process and removing a region including a part of the semiconductor layers in the vertical direction of the part or the whole, Are spaced apart in a net shape. The method according to claim 1, Wherein the metal wires connect the light emitting cells to each other and are connected to an external power supply lead. The method according to claim 5 or 7, Wherein the laser lift-off process is a Krf (248 nm) laser.

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