KR101340322B1 - Lateral power LED - Google Patents

Abstract

The present invention relates to a horizontal LED device, and more particularly to a horizontal power LED device capable of high output and high efficiency by manufacturing using the advantages of the conventional horizontal LED and vertical LED manufacturing method.

Description

Horizontal power LED device {Lateral power LED}

The present invention relates to a horizontal LED device, and more particularly to a horizontal power LED device capable of high output and high efficiency by manufacturing using the advantages of the conventional horizontal LED and vertical LED manufacturing method.

In general, the structure of a horizontal LED device is based on a light emitting structure consisting of one active layer (MQWS) emitting light and two cladding layers (p-GaN, n-GaN) surrounding the light, as shown in FIG. 1A. Form. The cladding layer in contact with the electrode is n-doped or p-doping, respectively, and the cladding layer portion in contact with the substrate is n-doping and the other cladding layer portion is p-doping. When a voltage is applied through the electrode according to the polarity of the doped cladding layer, electrons are supplied from the n-doped cladding layer and holes are supplied from the pdoped cladding layer, and these electrons and holes combine in the center active layer to emit light as current flows. . The substrate is mainly used for reflecting or transmitting a part of the emitted light according to the wavelength of the light emitted by the sapphire substrate having a low thermal conductivity and insulation. The horizontal LED device having such a structure has a high horizontal current spreading, a lot of current crowding, uneven light emission, and a light emitting area per chip, which is disadvantageous for a large area.

As shown in FIG. 1B, the flip chip type LED is actually inverted and inverted from the horizontal type by fixing a stud bump on the silicon submount. The basic structure of the light emission is the same as the horizontal type LED. Since the flip chip type LED emits light through the substrate, the light extraction to the substrate is improved, and thus the heat dissipation and high output characteristics are excellent, but sub-mount and soldering processes should be added.

As shown in FIG. 1C, a thin GaN LED also maintains its original shape without removing a portion of the stacked layer by etching in a basic light emitting structure such as a horizontal LED. In general, the bonding / reflector and the receptor substrate are sequentially attached to the laminated cladding layer, and then the electrodes are formed and the opposite substrate is separated. Forming an electrode on the cladding layer of the separated substrate completes the basic structure of the vertical LED. Light emitted from the active layer of the vertical LED is vertically reflected by the reflector of the lower side and emitted to the upper part, and has excellent heat dissipation and high output characteristics. The vertical LED device having such a structure has a low vertical current spreading, a reduced current crowding, and an enlarged emission area, which is advantageous for a large area, but has a problem in that the process is complicated and the yield is reduced.

Therefore, it is time to develop a new component LED device and a method of manufacturing the same, in which the disadvantages of the conventionally known LED device are eliminated.
Prior art literature
1. International Publication WO2011 / 010436 (2011. 1.17)
2. Published Patent Publication No. 10-2008-0018084 (2008.2.27)

The present inventors have completed the present invention by incorporating the advantages of the vertical LED device to the horizontal LED device as a result of research efforts to solve the problems of the prior art.

Accordingly, it is an object of the present invention to provide a horizontal type power LED device having a structure capable of minimizing light emission area reduction due to an electrode, thereby exhibiting high output and high efficiency.

Another object of the present invention is to provide a horizontal power LED device having a structure capable of maintaining the thickness of the n clad layer is advantageous for current spreading and can exhibit high power and high efficiency.

It is still another object of the present invention to provide a horizontal power LED device having an N-electrode formed on a conventional Ga-face and thus having a low Vf structure, which can exhibit high power and high efficiency.

It is still another object of the present invention to provide a horizontal power LED device having a structure in which current spreading is performed horizontally but overall spreading is made of a buried grid electrode so that current crowding does not appear.

Another object of the present invention is formed of a metal substrate has the characteristics of the conventional vertical chip, and also has a flip chip characteristics without sub-mount or sodering process, irregularities can also be formed to improve the light extraction efficiency high output and It is to provide a horizontal power LED device having a structure that can exhibit high efficiency.

The objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

In order to achieve the above object of the present invention, the present invention provides a light emitting structure in which an n-type gallium nitride-based semiconductor layer (n-GaN layer), an active layer and a p-type gallium nitride-based semiconductor layer (p-GaN layer) is sequentially stacked ; A p-type electrode formed on a surface of the p-GaN layer of the light emitting structure that is not adjacent to the active layer; An n-type electrode formed on a rear surface of the n-GaN layer of the light emitting structure adjacent to the active layer; An insulating film formed on the entire surface side of the p-GaN layer of the light emitting structure to expose the p-type electrode; A metal substrate formed to cover the insulating film and the p-type electrode; And an n-pad formed to be connected to the n-type electrode through a through hole formed on a surface of the n-GaN layer of the light emitting structure.

In a preferred embodiment, it further comprises a concave-convex formed on the surface of the n-GaN layer of the light emitting structure except for the through-hole formed with the n-pad.

In an exemplary embodiment, the semiconductor device may further include a seed layer formed between the insulating layer and the p-type electrode and the metal substrate.

In a preferred embodiment, the seed layer is used as a reflective film layer when the p-type electrode is a transparent electrode.

In a preferred embodiment, the metal substrate comprises at least one of copper (Cu), nickel, gold (Au), molybdenum (Mo).

The present invention has the following excellent effects.

First, the horizontal power LED device of the present invention can minimize the light emitting area reduction due to the electrode can exhibit high output and high efficiency.

In addition, the horizontal power LED device of the present invention can maintain the n clad layer thickness can exhibit high power and high efficiency.

In addition, in the horizontal power LED device of the present invention, the N-electrode is formed on a conventional Ga-face, which enables low Vf, thereby indicating high output and high efficiency.

In addition, the horizontal power LED device of the present invention has a current spreading horizontally, but the overall spreading is made of a grid-type electrode that is buried, so the current crowding phenomenon does not appear, which may indicate high power and high efficiency.

In addition, the horizontal power LED device of the present invention is formed of a metal substrate has the characteristics of the existing vertical chip, and also has a flip chip characteristic without sub-mount or sodering process, and irregularities can be formed to improve the light extraction efficiency. Can exhibit high power and high efficiency.

1A and 1C are schematic perspective views showing an outline of a horizontal LED device, a flip chip LED device, and a vertical LED device, respectively.
Figure 2 is an exploded perspective view showing a horizontal power LED device according to an embodiment of the present invention.
3 is a flowchart illustrating a method of manufacturing a horizontal power LED device according to preferred embodiments of the present invention.
4A to 4G are cross-sectional views and plan views illustrating a specific process of manufacturing a horizontal power LED device according to another preferred embodiment of the present invention.
4A to 4H are cross-sectional views and plan views illustrating a specific process of manufacturing the horizontal power LED device of FIG. 2.

Although the terms used in the present invention have been selected as general terms that are widely used at present, there are some terms selected arbitrarily by the applicant in a specific case. In this case, the meaning described or used in the detailed description part of the invention The meaning must be grasped.

Hereinafter, the technical structure of the present invention will be described in detail with reference to the accompanying drawings and preferred embodiments.

However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Like reference numerals used to describe the present invention throughout the specification denote like elements.

The technical feature of the present invention is to minimize the emission area due to the electrode, to maintain the n clad layer thickness, and to employ the method of manufacturing a vertical LED device in manufacturing a horizontal LED device, It can be formed on a Ga-face, and has a structure formed of a metal substrate, so it is a horizontal power LED device having high output and high efficiency.

Accordingly, the horizontal power LED device of the present invention includes a light emitting structure in which an n-type gallium nitride-based semiconductor layer (n-GaN layer), an active layer and a p-type gallium nitride-based semiconductor layer (p-GaN layer) are sequentially stacked; A p-type electrode formed on a surface of the p-GaN layer of the light emitting structure that is not adjacent to the active layer; An n-type electrode formed on a rear surface of the n-GaN layer of the light emitting structure adjacent to the active layer; An insulating film formed on the entire surface side of the p-GaN layer of the light emitting structure to expose the p-type electrode; A metal substrate formed to cover the insulating film and the p-type electrode; And an n-pad formed to be connected to the n-type electrode through a through hole formed on a surface of the n-GaN layer of the light emitting structure.

Referring to FIG. 2, which is an exploded perspective view showing a schematic outline of a horizontal power LED device according to an exemplary embodiment of the present invention, the horizontal power LED device 100 is insulated from an insulating film on a metal substrate 150. It can be seen that the structure 140 is formed. In particular, the light emitting structure 110 is formed to be located at the upper center side of the horizontal power LED device 100, one side and the lower surface of the light emitting structure 110 is surrounded by an insulating film, the lower portion is not surrounded by the insulating film p It can be seen that the type electrode is formed, and the n-GaN layer 111 of the light emitting structure 110 forms a top surface of the horizontal power LED device 100 in a form surrounded by the insulating layer 140.

The light emitting structure 110 is also called an epi layer, and has an n-type gallium nitride based semiconductor layer (n-GaN layer 111), an active layer 112, and a p-type gallium nitride based semiconductor layer (p-GaN layer 113). This is a semiconductor layer stacked sequentially.

At this time, the n-GaN layer 111, the active layer 112 and the p-GaN layer 113 is Al x In y Ga (1-xy) N composition formula (where 0≤x≤1, 0≤x≤1, 0≤x + y ≤ 1), and a known nitride deposition process such as a metal organic chemical vapor deposition (MOCVD) or a molecular beam crystal growth system (Molecular Beam Epitaxy, MBE) process. It can be formed through. The active layer 112 may be formed of any one of a multi quantum well or a single quantum well in which several quantum wells are stacked.

As such, the light emitting structure 110 is a structure in which an n-GaN layer 111, an active layer 112, and a p-GaN layer 113 are sequentially stacked from an upper side to a lower side. The p-type electrode 120 is formed on the surface not adjacent to 112, the n-type electrode 130 is formed on the back surface adjacent to the active layer 112 among the n-GaN layers, and the n-type electrode 130 Since the light emitting structure 110 is formed to be buried below the n-GaN layer 111, the light emitting structure 110 is formed on the surface of the n-GaN layer 111 of the light emitting structure 110, that is, the upper surface of the horizontal power LED device 100. The n-pad 160 is formed to be connected to the n-type electrode 111 through the through hole.

The metal substrate 150 may include at least one of copper (Cu), nickel, gold (Au), and molybdenum (Mo). In particular, the copper (Cu) layer, the nickel (Ni) layer, and copper (Cu) / Gold (Au) layer, nickel (Ni) / gold (Au) layer, copper (Cu) / nickel (Ni) / gold (Au) layer, nickel (Ni) / copper (Cu) / gold (Au) layer, It may be a nickel (Ni) / molybdenum (Mo) / nickel (Ni) / gold (Au) layer.

In addition, the metal substrate 150 is formed to a sufficient thickness to support the semiconductor structure, and finally, when performing a cutting process including a laser scribing process to separate each unit into a LED device, such as a laser Providing a surface on which the notch is directly formed by the cutting device prevents the light emitting structure 110 from being damaged.

In addition, although not shown, the surface of the n-GaN layer 111 may be further formed with the concave-convex 114 configured to optimize the photon escape angle by increasing the light extraction efficiency through the surface roughness process.

That is, when the upper surface of the light emitting structure 110 is flat, most of the light exiting to the outside having a perpendicular or similar angle to the upper surface of the light emitting structure 110 cannot be extracted to the outside, but has irregularities formed on the upper surface. This can reduce the escape angle with the upper surface when the light is extracted to the outside, that is, it can increase the luminous efficiency of the horizontal type LED chip by increasing the external light extraction efficiency.

Although not shown, a seed layer formed between the insulating layer 140 and the p-type electrode 120 and the metal substrate 150 may be further included. The presence or absence of the seed layer may be defined in the method of forming the metal substrate 150. It may vary depending on, it is preferable that the seed layer is included when the metal substrate 150 is formed by a plating process. Optionally, in the horizontal power LED device of the present invention, when the p-type electrode is a transparent electrode, the seed layer may be formed to be used as a reflective film layer.

As a result, according to the structure of the horizontal type power LED device 100 according to the present invention, the current is injected only by the n-pad 160, and the n-electrode 130 formed in a predetermined form including a grid is embedded. Therefore, it is possible to minimize the emission area reduction due to the electrode.

That is, the horizontal power LED device of the present invention has a structure capable of eliminating the emission area reduction that may occur due to the formation of n-type electrodes in a grid pattern on the light emitting surface to facilitate current spreading while the existing vertical chip becomes large. Because you will have.

In addition, current spreading is done horizontally, but overall spreading consists of a grid-type electrode that is embedded, there is no current crowding phenomenon, and it is formed of a metal substrate 150, which has the characteristics of a conventional vertical chip, and has no sub-mount or soldering process. It can be seen that flip chip characteristics are also obtained.

3 is a flowchart illustrating a method of manufacturing a horizontal power LED device according to preferred embodiments of the present invention, and FIGS. 4A to 4G illustrate specific processes of manufacturing a horizontal power LED device according to another preferred embodiment of the present invention. 4A to 4H are cross-sectional views and a plan view illustrating a specific process of manufacturing the horizontal power LED device of FIG. 2.

Referring to Figure 3, the horizontal power LED device manufacturing method of the present invention will be described in detail. First, the horizontal power LED device manufacturing method of the present invention includes a light emitting structure forming step (S210), a light emitting structure etching step (S220), an electrode forming step (S230), an insulating film forming step (S240), a metal substrate forming step (S250), Substrate removal step (S260), n-pad forming step (S270) is included. When forming a plurality of chips may further include a cutting step (S280).

First, the light emitting structure forming step (S210) is performed. The light emitting structure forming step (S210) is performed on an n-type gallium nitride based semiconductor layer (n-GaN layer), an active layer, and a p-type gallium nitride based semiconductor layer (p−). Forming a light emitting structure in which GaN layers) are sequentially stacked.

The substrate 101 is prepared as shown in FIG. 4A. The substrate 101 may be formed using a transparent material including sapphire, and zinc oxide (ZnO), gallium nitride (GaN), silicon carbide (SiC), and aluminum nitride (AIN) may be used in addition to sapphire. The n-GaN layer 111, the active layer 112, and the p-GaN layer 113 are sequentially stacked on the substrate 101.

In some cases, an undoped gallium nitride semiconductor layer (u-GaN layer, not shown) may be further formed on the substrate 101 before the n-GaN layer 111 is formed. In addition, in order to improve the characteristics of the light emitting structure 110, that is, the epi layer, and to minimize the loss of the epi layer when removing the substrate 101 in a subsequent process, a u-GaN layer (not shown) is disposed on the substrate 101. A buffer layer (not shown) may be further laminated before lamination.

Next, the light emitting structure etching step S220 is performed. In the light emitting structure etching step S220, the n-GaN layer 111 is exposed and the substrate 101 is exposed to form a separation part corresponding to a predetermined chip size. The light emitting structure 110 is etched to be effective.

As shown in FIG. 4B, the p-GaN layer 113 and the active layer 112 are etched to expose the n-GaN layer 111 with the p-GaN layer 113 at the center thereof, and then the exposed n− Etching is performed such that the substrate 101 is exposed so that a separation portion is formed at an end side of the GaN layer 111. At this time, the exposed shape of the n-GaN layer 111 is determined according to the pattern to form the n-type electrode. As shown in the plan view, the p-GaN layer 113 is exposed so that the n-GaN layer 111 is exposed in a grid shape. ) And the active layer 112 are etched, and the substrate 101 is etched to expose the separation portion to surround the exposed end of the n-GaN layer.

Although not shown, the light emitting structure etching step (S220) may be performed by etching the substrate 101 to expose the separator so that only a part of the n-GaN layer 111 of the light emitting structure 110 is exposed. That is, first, the light emitting structure 110 is etched to a chip size so that the substrate 101 is exposed, and then the side surfaces of the n-GaN layer 111, the active layer 112, and the p-GaN layer 113 are etched. This is because the n-GaN layer 111 may be etched by exposing the active layer 112 without etching the p-GaN layer 113 in the exposed state. In this case, in the state where the LED device is finally completed, the n-GaN layer 111 and the p-GaN layer 113 have the same area.

 Next, an electrode forming step (S230) is performed, and the electrode forming step (S230) forms a p-type electrode 120 on the p-GaN layer 113 and on the exposed n-GaN layer 111. The n-type electrode 130 is formed.

As shown in FIG. 4C, the p-type electrode 120 and the n-type electrode 130 are formed, and the p-type electrode 120 and the n-type electrode 130 may be formed at different time points regardless of the order. It may be formed at the same time. Here, the n-type electrode 130 may be formed in a grid shape according to the shape of the n-GaN layer 111 exposed in the light emitting structure etching step S220.

Next, an insulating film forming step S240 is performed. The insulating film forming step S240 is performed by depositing the insulating film 140 so as to cover the p-GaN layer 113 and the exposed n-GaN layer 111. The insulating layer 140 is etched to expose the p-type electrode 120 formed on the GaN layer 113.

As shown in FIG. 4D, when the insulating film forming step S40 is performed, even the separation part formed by exposing the substrate 101 is covered with the insulating film 140, and as can be seen from the plan view, the p-type electrode 120 and the insulating film 140. ) Can only be observed.

Next, the metal substrate forming step S250 is performed, and the metal substrate forming step S250 is a step of forming the metal substrate to cover the insulating layer 140 and the p-type electrode 120.

As shown in FIG. 4E, when the metal substrate forming step S250 is performed, a metal substrate having a predetermined thickness is formed to cover the light emitting structure 110 to have an upper surface parallel to the substrate 101 positioned below. have. The metal substrate 150 may be formed by various methods. Although not shown, the metal substrate 150 may be formed by the insulating layer 140 and the plating substrate may be easily performed before the metal substrate forming step S250. The method may further include forming a seed layer to cover the p-type electrode 120. As such, when the seed layer is formed, the p-type electrode may be used as a reflective layer when the transparent electrode is formed.

Next, a substrate removal step (S260) is performed. The substrate removal step (S260) is a step of removing the substrate 101 from the light emitting structure 110.

As shown in FIG. 4F, when the substrate removing step S260 is performed, the light emitting structure 110 becomes an upper surface and the metal substrate 150 is disposed upside down to facilitate the subsequent process. desirable. The removal of the substrate 101 may be performed in a known manner, and is preferably performed through a laser lift off method (LLO) or chemical lift off method (CLO) using a laser. This is more advantageous.

Next, an n-pad forming step S270 is performed, and the n-pad forming step S270 is performed by the n-type electrode 130 and the n-GaN layer 111 side surface of the light emitting structure 110. Forming a through hole to be connected, and depositing the n-pad 160 to be connected to the n-type electrode 130 through the through hole.

As shown in Figure 4g, when the n-pad forming step (S270) is performed it can be seen that the horizontal power LED device according to another embodiment of the present invention is completed. That is, when the n-pad 160 is formed, the current can be injected through the n-pad to the n-type electrode embedded in the light emitting structure 110.

Therefore, the conventional vertical LED device has a loss of n Clad layer for current spreading by performing a substantial portion of etching to remove the sapphire substrate and expose the n-GaN layer, but n clad layer thickness according to the manufacturing method of the present invention. It can be maintained, which is good for current spreading. In addition, the surface of the n-GaN layer exposed after the removal of the substrate 101 has N-face polarity, and there is a loss in n-omic electrode formation because there is a mechanical difference from the ohmic formation in the conventional Ga-face polarity. , n-type electrode is formed on the existing Ga-face to enable a low Vf.

Optionally, although not shown in FIG. 3, as shown in FIG. 4H, the unevenness 114 is formed on the n-GaN layer 111 side surface of the light emitting structure 110 before or after performing the n-pad forming step S270. ) May be further performed to form the unevenness forming.

As shown in FIG. 4H, the unevenness 114 for optimizing the photon escape angle is formed on the upper surface of the light emitting structure 110, that is, the n-GaN layer 111, for example, through unevenness through wet etching. 114 may be formed, and the shape of the unevenness 114 may be formed in a polygonal shape or a random shape such as a rhombus shape in addition to the illustrated triangle, but is not limited to a specific shape.

Finally, as shown in FIG. 3, when the process of FIGS. 4A to 4G or 4A to 4H is performed to form a plurality of chips, the unit LED is cut by cutting the separator to include each light emitting structure 110. Each of the elements 100 is separated. Cutting may be performed by laser scribing or wheel cutting.

Through this process (FIGS. 4A to 4H), the horizontal power LED device 100 as illustrated in FIG. 2 may be manufactured.

The horizontal power LED device of the present invention manufactured by the above-described manufacturing method can minimize the emission area reduction due to the electrode, maintain the n clad layer thickness, and form the N-electrode on the existing Ga-face, Not only has a structure formed of a metal substrate, the concave-convex is formed on the upper surface of the light emitting structure to reduce the reflectance of the light can increase the light extraction efficiency of the light formed in the active layer to the outside can have a high output and high efficiency.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be construed as limiting the scope of the invention as defined by the appended claims. Various changes and modifications may be made by those skilled in the art.

100: horizontal power LED element 101: substrate
110 light emitting structure 111 n-GaN layer
112: active layer 113: p-GaN layer
114: unevenness 120: p-type electrode
130: n-type electrode 140: insulating film
150: metal substrate 160: n-pad

Claims (5)

a light emitting structure in which an n-type gallium nitride-based semiconductor layer (n-GaN layer), an active layer and a p-type gallium nitride-based semiconductor layer (p-GaN layer) are sequentially stacked;
A p-type electrode formed on a surface of the p-GaN layer of the light emitting structure that is not adjacent to the active layer;
An n-type electrode formed on a rear surface of the n-GaN layer of the light emitting structure adjacent to the active layer;
An insulating film formed on the entire surface side of the p-GaN layer of the light emitting structure to expose the p-type electrode;
A metal substrate formed to cover the insulating film and the p-type electrode; And
It includes; n-pad formed to be connected to the n-type electrode through a through hole formed in the n-GaN layer surface of the light emitting structure,
The n-type electrode is a horizontal power LED device, characterized in that all the surface that is not interviewed with the n-GaN layer is surrounded by the insulating film.
The method of claim 1,
Horizontal power LED device, characterized in that it further comprises irregularities formed on the surface of the n-GaN layer of the light emitting structure except the through-hole formed with the n-pad.

3. The method according to claim 1 or 2,
And a seed layer formed between the insulating film and the p-type electrode and the metal substrate.
The method of claim 3, wherein
And the seed layer is used as a reflective layer when the p-type electrode is a transparent electrode.
3. The method according to claim 1 or 2,
The metal substrate is a horizontal power LED device comprising at least one of copper (Cu), nickel, gold (Au), molybdenum (Mo).

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