KR20120031586A - Vertical structure led device and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a vertical structure light emitting diode device and a method for manufacturing the same, which efficiently discharge heat generated in a semiconductor layer to enable stable operation. Vertical structure LED device of the present invention is a lower surface support layer formed with a heat radiation pattern of irregularities; A semiconductor layer supported by the support layer, the semiconductor layer comprising a lower semiconductor layer, an active layer, and an upper semiconductor layer; And an upper electrode layer formed on the semiconductor layer. In addition, the vertical structure LED device manufacturing method of the present invention comprises the steps of growing a semiconductor layer on a substrate; Forming a support layer on the semiconductor layer; Separating the substrate from the semiconductor layer; Forming an upper electrode on the semiconductor layer; And forming a heat dissipation pattern on a lower surface of the support layer.

Description

Vertical structure LED device and manufacturing method thereof

The present invention relates to a light emitting diode device, and more particularly, to a vertical structure light emitting diode device and a method of manufacturing the same to efficiently discharge heat generated in the semiconductor layer and to operate stably.

A gallium nitride (GaN) based light emitting diode (LED) is generally manufactured by growing on a sapphire substrate. However, the sapphire substrate is hard, electrically non-conductive, and the thermal conductivity is poor, there is a limit in reducing the size of the device to reduce the manufacturing cost, or improve the light output and the characteristics of the chip. In particular, in order to increase the output power of the LED device is required to apply a large current, it is very important to solve the heat dissipation problem of the LED device. As a means to solve this problem, a vertically structured gallium nitride based LED device is proposed in which a semiconductor layer is grown on a sapphire substrate and then the sapphire substrate is removed by laser lift-off (LLO) technology. It became.

1 is a cross-sectional view showing a vertical structure gallium nitride based LED device 1 according to the prior art. The conventional LED device 1 forms a structure in which the light emitting structure 30 is formed on the support structure 10. In addition, a p-type electrode 20 is formed between the support structure 10 and the light emitting structure 30, and an n-type electrode 50 is formed above the light emitting structure 30.

The light emitting structure 30 is formed of a gallium nitride based semiconductor layer, and has a structure in which the p-type semiconductor layer 31, the active layer 32, and the n-type semiconductor layer 33 are sequentially stacked. The p-type electrode 20 is composed of an ohmic contact and a reflective metal, and simultaneously serves as an electrode and a reflective film. In addition, a transparent electrode 40 for further improving optical characteristics is further formed between the n-type semiconductor layer 33 and the n-type electrode 50. In addition, the support structure 10 prevents damage to the light emitting structure 30 by the LLO process, and supplies a current to the light emitting structure 30 and at the same time serves as a path for dissipating heat generated from the light emitting structure 30. To perform. To this end, the support structure 10 is a material having excellent thermal conductivity as well as electrical conductivity is used.

However, as described above, the vertical structured LED device according to the related art is manufactured in a planar shape on a lower surface of the support structure 10. Although the structure of the support structure 10 is made of a material having excellent heat dissipation properties, the structure of the support structure 10 becomes a heat dissipation area, which inevitably has a limit to sufficiently release heat generated from the light emitting structure. .

The present invention has been proposed to solve the above problems, and an object of the present invention is to provide a vertical structured LED device and a method of manufacturing the same, which can efficiently release heat generated in the semiconductor layer by securing a sufficient heat dissipation area. .

Vertical structure LED device of the present invention for achieving the above object is a lower surface support layer formed with a heat dissipation pattern; A semiconductor layer supported by the support layer, the semiconductor layer comprising a lower semiconductor layer, an active layer, and an upper semiconductor layer; And an upper electrode layer formed on the semiconductor layer.

In the above-described configuration, the heat radiation pattern is characterized by forming a stripe shape or a pillar shape.

In the above-described configuration, a lower electrode layer is further formed between the support layer and the semiconductor layer.

In addition, the vertical structure LED device manufacturing method of the present invention comprises the steps of growing a semiconductor layer on a substrate; Attaching a support layer on the semiconductor layer; Separating the substrate from the semiconductor layer; Forming an upper electrode on the semiconductor layer; And forming a heat dissipation pattern on a lower surface of the support layer.

In the above-described configuration, the heat dissipation pattern is formed on the lower surface of the support layer, characterized in that the process of attaching the support layer on which the heat dissipation pattern is formed on the semiconductor layer.

The vertical structured LED device having the above-described configuration can relatively expand the heat dissipation area when compared with the support layer having the same size by the heat dissipation pattern formed on the lower surface of the support layer. As a result, heat generated in the semiconductor layer is efficiently discharged through the heat radiation pattern of the support layer, so that the LED element operates stably and durability is improved.

1 is a cross-sectional view showing a vertical structure type LED device according to the prior art,
2 is a cross-sectional view showing a vertical structure type LED device according to an embodiment of the present invention;
3A to 3C are rear perspective views illustrating various embodiments of a support layer structure of a vertical structured LED device according to the present invention; and
4A through 4E are cross-sectional views illustrating a process of manufacturing the LED device of FIG. 2.

The technical problem achieved by the present invention and the practice of the present invention will be apparent from the preferred embodiments described below. The following examples are merely illustrated to illustrate the present invention and are not intended to limit the scope of the present invention. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a cross-sectional view showing a vertical structure type LED device according to an embodiment of the present invention. As shown in the LED device 100, the p-type electrode 120 is formed on the support layer 110, and the p-type semiconductor layer 131, the active layer 132, and the p-type electrode 120 are formed on the support layer 110. The semiconductor layer 130 formed of the n-type semiconductor layer 133 is formed. In addition, the n-type electrode 150 is formed on the n-type semiconductor layer 133 via the transparent electrode 140.

Here, the support layer 110 is configured to prevent damage to the semiconductor layer 130. In the vertical structured gallium nitride-based LED device, the semiconductor layer 130 is grown on the sapphire substrate (see 200 of FIG. 4A), and after the semiconductor layer 130 is grown, the sapphire substrate 200 is removed by using an LLO process. do. In this case, since the semiconductor layer 130 may be damaged by high heat during the LLO process, the semiconductor layer 130 is protected by attaching the support layer 110 to the p-type electrode 120. In addition, the support layer 110 supplies a current through the p-type electrode 120, and serves as a passage for dissipating heat generated from the semiconductor layer 130 to the outside. To this end, the support layer 110 may be formed of a material having excellent thermal conductivity as well as electrical conductivity. For example, the support layer 110 may include a Cu substrate, a Si substrate, a GaAs substrate, or a Ge substrate.

In particular, in the support layer 110 of the present invention, the heat radiation patterns 111 having various shapes are formed on the lower surface of the support layer 110 to quickly release heat generated from the semiconductor layer 130. The heat dissipation pattern 111 is formed to increase the area of the lower surface of the support layer 110, which in turn increases the area for dissipating heat. That is, a relatively large heat dissipation area is formed with respect to the support layer 110 of the same size, which may exhibit excellent heat dissipation effect. The specific shape of the heat radiation pattern 111 will be described later.

The p-type electrode 120 and the n-type electrode 150 are configured to supply current to the semiconductor layer 130. Here, the p-type electrode 120 is formed in a multilayer structure in which the ohmic layer 122 and the reflective layer 121 are sequentially stacked. The p-type electrode 120 may be formed of a single layer structure of metal having both ohmic and light reflecting properties. In addition, the n-type electrode 150 is formed as small as possible compared to the n-type semiconductor layer 133 in order not to interfere with the light emission. Therefore, an ITO transparent electrode 140 is further formed between the n-type semiconductor layer 133 and the n-type electrode 150 to improve the spread of the current flowing through the n-type electrode 150. In this case, a light pattern is formed on the upper surface of the transparent electrode 140 to improve light characteristics of the emitted light.

The semiconductor layer 130 is configured to generate light based on the principle of p-n junction, and includes a p-type semiconductor layer 131, an active layer 132, and an n-type semiconductor layer 133. The p-type semiconductor layer 131 and the n-type semiconductor layer 133 may be doped with p-type and n-type conductive impurities, respectively, in a gallium nitride (GaN) -based compound. For example, in the present invention, Mg and Si are doped, respectively. In addition, the active layer 132 is formed of a gallium nitride layer having a multi-quantum well structure.

In the LED device 100 having the above-described configuration, when a voltage is applied through each of the electrodes 120 and 150, electrons move from the n-type semiconductor layer 133, and holes move from the p-type semiconductor layer 131. Recombination of electrons and holes occurs in the active layer 132 to emit light. Heat generated in this process is discharged to the outside through the heat radiation pattern 111 of the support layer 110.

Meanwhile, in the embodiment of the present invention, the lower semiconductor layer is composed of a p-type semiconductor layer and the upper semiconductor layer is composed of an n-type semiconductor layer, but vice versa. In addition, although the structure in which the lower electrode layer is formed between the support layer and the semiconductor layer has been described, the structure may also be implemented in which the lower electrode layer is removed. That is, since the semiconductor layer is directly formed on the support layer, the support layer functions as a lower electrode, thereby simplifying the structure and manufacturing process.

3A to 3C are rear perspective views illustrating various embodiments of the support layer structure of the vertical structured LED device according to the present invention, and show heat radiation patterns 111 having various shapes formed on the bottom surface of the support layer 110. The heat dissipation pattern 111 formed on the lower surface of the support layer 110 of the LED device 100 has an uneven shape to maximize the heat dissipation area. As an example, as shown in FIGS. 3A to 3C, it may be formed in a stripe shape, a pillar shape, or a lens shape. The heat dissipation pattern 111 of the present invention is not limited to this shape and may be formed in various patterns to maximize the heat dissipation area. On the other hand, the heat radiation pattern 111 of the stripe shape or columnar shape has an advantage that the pattern manufacturing process is easy, and the heat radiation area can be easily adjusted according to the height of the pattern.

4A through 4E are cross-sectional views illustrating a process of manufacturing the LED device of FIG. 2. In the LED device 100 of the present invention, first, as shown in FIG. 4A, the n-type semiconductor layer 133, the active layer 132, and the p-type semiconductor layer 131 are sequentially grown on the sapphire substrate 100. Let's do it. In addition, the p-type electrode 120 including the ohmic layer 122 and the reflective layer 121 is formed on the p-type semiconductor layer 131. The semiconductor layer 130 may be formed by, for example, an epitaxial growth method using metal organic chemical vapor deposition (MOCVD). In this case, the buffer layer 210 may be formed between the sapphire substrate 200 and the n-type semiconductor layer 133 to match the lattice constant. The buffer layer 210 is formed of a pure undoped gallium nitride layer.

Thereafter, as shown in FIG. 4B, a support layer is formed on the p-type electrode 120. The support layer 110 is configured to prevent the semiconductor layer 130 from being damaged in the process of separating the sapphire substrate 200. In addition, the support layer 110 applies a current to the p-type electrode, and uses a material such as Cu, Si, GaAs, or Ge to release heat generated from the semiconductor layer 130. After forming the support layer 110, as shown in FIG. 4C, the sapphire substrate 200 is separated from the semiconductor layer 130 using an LLO process. In this case, the buffer layer 210 is also removed by the etching process.

As shown in FIG. 4D, the transparent electrode 140 is formed on the n-type semiconductor layer 133 on which the sapphire substrate 200 is separated and exposed, and the plurality of n-types are formed on the transparent electrode 140 at regular intervals. An electrode 150 is formed. Thereafter, as illustrated in FIG. 4E, a heat radiation pattern 111 is formed on the bottom surface of the support layer 110. In this case, the heat radiation pattern 111 may be formed using an etching process, and a lapping process may be performed so that the support layer 110 has a predetermined thickness before the heat radiation pattern 111 is formed. After the heat radiation pattern 111 is formed, the LED devices are finally manufactured by separating the devices by laser scribing.

On the other hand, in the manufacturing process of the LED device according to the above-described embodiment, the process of forming the lower electrode layer can be removed to further simplify the process. In this case, the support layer serves as the lower electrode. In addition, although the manufacturing process illustrated in FIGS. 4A to 4E is performed by forming a heat dissipation pattern on the support layer formed on the semiconductor layer, the process may be performed by attaching the support layer on which the heat dissipation pattern is formed on the semiconductor layer. That is, after the heat radiation pattern is formed in advance on the support layer in a separate process, the support layer may be attached onto the semiconductor layer. In this case, it is possible to prevent the semiconductor layer from being damaged during the heat radiation pattern formation process.

As described above, since the heat dissipation pattern 111 is formed on the lower surface of the support layer 110, the vertical structure LED device 100 exhibits an effect of maximizing the emission of heat generated from the semiconductor layer 130. .

Although the embodiments of the present invention have been described with reference to the present invention, those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the scope of the present invention is not limited thereto, but various modifications and improvements of those skilled in the art using the basic concept of the present invention as defined in the following claims also fall within the scope of the present invention.

100: LED element 110: support layer
120: p-type electrode 130: semiconductor layer
140: transparent electrode 150: n-type electrode
111: heat dissipation pattern

Claims (5)

A support layer having a heat dissipation pattern having a concave-convex shape on a lower surface thereof;
A semiconductor layer supported by the support layer, the semiconductor layer comprising a lower semiconductor layer, an active layer, and an upper semiconductor layer; And
And an upper electrode layer formed above the semiconductor layer.
The heat dissipation pattern of claim 1, wherein
Vertical structure type LED device characterized by forming a stripe shape or a columnar shape.
The method according to claim 1 or 2,
And a lower electrode layer is further formed between the support layer and the semiconductor layer.
Growing a semiconductor layer on the substrate;
Attaching a support layer on the semiconductor layer;
Separating the substrate from the semiconductor layer;
Forming an upper electrode on the semiconductor layer; And
Forming a heat radiation pattern on the lower surface of the support layer; Vertical structure type LED device manufacturing method comprising a.
The heat dissipation pattern of claim 4, wherein
Forming first on the lower surface of the support layer, and then attaching the support layer on which the heat radiation pattern is formed on the semiconductor layer.

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