KR20050021142A - Light emitting device and fabrication method thereof - Google Patents

Abstract

PURPOSE: A light emitting device is provided to improve an electro-optical characteristic and optical output efficiency by effectively radiating the heat generated from a light emitting device. CONSTITUTION: A substrate(111) is prepared which has higher thermal conductivity than GaAs. A p-n junction diode(120,140) is formed. A bonding medium layer bonds the substrate to the p-n junction diode, formed on the substrate. The p-n junction diode is made of a GaAs/AlGaAs-containing material or an InGaP/AlGaInP-containing material. The substrate is made of Si, AlN, SiC, CuW, Cu or Al.

Description

Light emitting device and manufacturing method thereof

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device and a method of manufacturing the same, and more particularly, to a light emitting device using a substrate having high thermal conductivity and a method of manufacturing the same.

Light emitting diodes (hereinafter referred to as LEDs) are used in various applications such as display, communication, and lighting.

1A is a schematic diagram showing a general conventional LED structure.

Referring to FIG. 1A, an LED is a Bragg reflector layer 12, an n-type cladding layer 13, a light emitting active layer 14, a p-type cladding layer 15, and a p-type window sequentially formed on a GaAs substrate 11. Layer, a p-type electrode 17 formed on the p-type window layer 16, and an n-type electrode 18 formed under the GaAs substrate 11.

1B is a schematic diagram showing the structure of a conventional vertical cavity light emitting diode (hereinafter referred to as RCLED).

Referring to FIG. 1B, the RCLED is an n-type Bragg reflector layer 21, a light emitting active layer 22, a current guide layer 23, a p-type Bragg reflector layer 24, and p formed sequentially on the GaAs substrate 11. The window layer 25, the p-type electrode layer 26 formed on the p-type window layer 25, the n-type electrode 27 formed below the GaAs substrate 11, and the dielectric protective film 28 on the upper side thereof. It is made to include.

Figure 1c is a schematic diagram showing the structure of a conventional vertical cavity surface emitting laser diode (hereinafter referred to as VCSEL).

Referring to FIG. 1C, the VCSEL has the same structure as the RCLED of FIG. 1B, but the n-type Bragg reflector layer 21 and the p-type Bragg reflector layer 24 have higher reflectances.

1A to 1C, when a substrate having a low thermal conductivity is used, heat generated in the light emitting active layer 14 is not easily released, and generation of photons is reduced due to scattering by heat, resulting in light output efficiency. There is a drawback to this.

In order to solve this problem, first, the thickness of the substrate having low thermal conductivity is reduced, and second, the heat sink is bonded to the heat sink by flip chip method to heat sink the pn junction of the light emitting diode. There is a way to place it closer. However, there is a problem that the first method is difficult to apply because of the risk of cracking at a thickness of 100 μm or less, and the second method is a method used in some cases, but the chip must be bonded to a heat sink with expensive equipment. There is a problem in that the process is complicated and the price rises and the competitiveness is lost. Therefore, there is a need to develop a method of removing a substrate having low thermal conductivity and bonding a substrate having high thermal conductivity.

Accordingly, an object of the present invention is to provide a light emitting device using a substrate having high thermal conductivity and a method of manufacturing the same.

According to an aspect of the present invention, there is provided a light emitting device comprising: a substrate having a higher thermal conductivity than GaAs; a p-n junction diode; And a junction media layer formed on the substrate to bond the substrate to the p-n junction diode.

For example, the light emitting device according to the present invention includes: the pn junction diode includes a p-type metal layer, a p-type window layer, a p-type cladding layer, an active layer, an n-type cladding layer, an n-type window layer, and an n-type metal layer, The pn junction diode is a vertical resonance light emitting diode including a p-type metal layer, a p-type window layer, a p-type Bragg reflector layer, a current guide layer, an active layer, an n-type Bragg reflector layer, an n-type window layer and an n-type metal layer, Or a vertical resonant surface emitting laser diode; When the substrate is a p-type substrate, the p-n junction diode and the p-type substrate is bonded by the junction media layer so that the junction media layer is located between the p-type metal layer and the p-type substrate.

A method of manufacturing a light emitting device according to an embodiment of the present invention described above includes: an n-type window layer, an n-type cladding layer, an active layer, a p-type cladding layer, a p-type window layer, and a p-type metal layer sequentially on an n-type GaAs substrate Or sequentially forming an n-type window layer, an n-type Bragg reflector layer, an active layer, a current guide layer, a p-type Bragg reflector layer, a p-type window layer, and a p-type metal layer on the n-type GaAs substrate; Bonding the p-type substrate to the p-type metal layer having a higher thermal conductivity than GaAs and to which an adhesive is applied to one surface by a rotation coating method; Removing the n-type GaAs substrate; And forming an n-type metal layer in a predetermined region of the exposed n-type window layer, and forming a p-type electrode.

As another example, the light emitting device according to the present invention may include: the pn junction diode includes a p-type metal layer, a p-type window layer, a p-type cladding layer, an active layer, an n-type cladding layer, an n-type window layer, and an n-type metal layer, The pn junction diode is a vertical resonance light emitting diode including a p-type metal layer, a p-type window layer, a p-type Bragg reflector layer, a current guide layer, an active layer, an n-type Bragg reflector layer, an n-type window layer and an n-type metal layer, Or a vertical resonant surface emitting laser diode; When the substrate is an n-type substrate, the p-n junction diode and the n-type substrate is bonded by the junction media layer so that the junction media layer is located between the n-type metal layer and the n-type substrate.

According to another aspect of the present invention, there is provided a method of manufacturing a light emitting device. An n-type window layer, an n-type cladding layer, an active layer, a p-type cladding layer, and a p-type window layer are sequentially formed on an n-type GaAs substrate. A p-type metal layer is formed in a predetermined area of a window type, or an n-type window layer, an n-type Bragg reflector layer, an active layer, a current guide layer, a p-type Bragg reflector layer, and a p-type window layer are sequentially formed on an n-type GaAs substrate. Forming a p-type metal layer in a predetermined region of the p-type window layer; Bonding the support substrate provided separately from the p-type metal layer; Removing the n-type GaAs substrate; Forming an n-type metal layer on the exposed n-type window layer; Bonding the n-type substrate and the n-type metal layer to which the thermal conductivity is higher than that of GaAs and to which an adhesive is applied to one surface by a rotation coating method; Removing the support substrate; forming an n-type electrode.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

2 and 3 are schematic diagrams for explaining embodiments of the present invention.

The present invention is characterized in that a substrate made of Si, CuW, Cu or Al having higher thermal conductivity than GaAs and having a thickness of 50 to 350 µm and a p-n junction diode are bonded using a junction medium layer. The thermal conductivity of Si is 145.7 W / mK, Cu is 401 W / mK, CuW is 401 W / mK, Al is 237 W / mK, and GaAs is 44 W / mK. At least three times more thermal conductivity. The p-n junction diode is made of GaAs / AlGaAs-based or InGaP / AlGaInP-based materials.

The bonding media layer consists of a non-conductive silicone-based adhesive applied on a substrate. As the non-conductive silicon-based adhesive, SOG (Spin on glass) or glass frit (Glass frit) may be used, and is coated with a thickness of 100 ?? ˜5 μm by a spin coating method, and may be approximately 400˜. Curing process at 500 ?? forms a dielectric film composed of Si _x O _y components and acts as a medium for bonding two adjacent materials. At this time, the optimum coating thickness by the rotation coating method which can raise thermal conductivity is 1000 ??-3000 ??.

On the other hand, the thermal conductivity becomes higher as the bonding medium layer is thinner, in order to form a thinner bonding medium layer than the coating using the rotation coating method may be used by chemical vapor deposition (CVD). In this case, a chemical vapor deposition method is used to deposit a dielectric film made of SiO ₂ or SiN to a thickness of 50 kV to 3000 kV on a substrate to form a medium material layer for joining the two materials.

When the non-conductive silicone-based adhesive is applied by the rotary coating method, the process is easier than the chemical vapor deposition method, and the production cost is low, and the productivity is high, and when the chemical vapor deposition method is used, the thermal conductivity is applied. Since there is an advantage of improving the degree, it is possible to select the cooking as needed.

The substrate junction is formed by placing the substrate and the p-n junction diode therebetween, and applying a suitable pressure at a suitable temperature.

Hereinafter, a light emitting diode to which the present invention is applied and a method of manufacturing the same will be described.

Example 1

Referring to FIG. 2, the p-type substrate 111 and the p-n junction diode 120 or 140 are bonded using an adhesive as a bonding medium layer.

The pn junction diode 120 of the LED shown in FIG. 2 (1) includes a p-type metal layer 126, a p-type window layer 125, a p-type cladding layer 124, an active layer 123, and an n-type cladding. It is a general pn junction diode for LED which comprises the layer 122, the n-type window layer 121, and the n-type metal layer 127. As shown in FIG.

The pn junction diode 140 of the LED shown in (2) of FIG. 2 includes p-type metal layers 147 and 147 ', p-type window layer 146, p-type Bragg reflector layer 145, and current guide layer ( 144), a pn junction diode for a general RCLED comprising an active layer 143, an n-type Bragg reflector layer 142, an n-type window layer 141, and an n-type metal layer 148, or has the same structure as n-LED The type Bragg reflector layer 142 and the p-type Bragg reflector layer 145 are pn junction diodes for VCSEL with higher reflectance. On the other hand, although not shown, the p-n junction diode for RCLED and VCSEL further includes a cladding layer and a dielectric protective film.

The p-type window layer serves to increase current spreading. When the current is diffused in the p-type window layer and the holes of the p-type cladding layer and the electrons of the n-type cladding layer are combined in the active layer, light of a wavelength according to the energy band gap is generated.

The p-type metal layer in ohmic contact on the entire surface of the p-type window layer serves not only as the ohmic contact metal but also as a reflector to reflect light from the active layer toward the substrate. The diffusion of the current in the p-type window layer does not need to be thick because current is spread by the p-type metal layer on the front surface.

2 (1) and 2 (2) have structural differences between the p-type electrodes 126, 147, and 147 'in addition to the differences between the pn junction diodes 120 and 140, the structural differences may be applied. This is not a difference for LEDs and can be compatible with each other. That is, a general LED may also have a structure as shown in FIG. 2, and RCLED or VCSEL may also have a structure as shown in FIG. 2.

The manufacturing method of the LED shown to FIG. 2 (1) is demonstrated.

First, an n-type window layer 121, an n-type cladding layer 122, an active layer 123, a p-type cladding layer 124, and a p-type window layer 125 are sequentially disposed on an n-type GaAs substrate (not shown). The p-type metal 126 is deposited on the p-type window layer 125. Here, the manufacturing method of the p-n junction diode 120 is not intended to limit the scope of the present invention, and all of the conventional manufacturing methods may be used, and thus the detailed description thereof will be omitted. The non-conductive silicon-based adhesive 130 is applied to the p-type substrate 111 having a higher thermal conductivity than GaAs by a spin coating method.

Then, the p-type metal layer 126 is brought into contact with the applied contact agent 130, and the p-type metal layer 126 and the p-type having the applied adhesive 130 as a bonding medium layer by applying a constant pressure under a constant temperature. Substrate bonding of the substrate 111 is performed.

Subsequently, the n-type GaAs substrate for p-n junction diode thin film growth is removed, and an n-type metal layer 127 is deposited on a predetermined region of the exposed n-type window layer 121 to perform ohmic contact. Then, by forming a p-type electrode for applying a current by etching a predetermined region of each thin film from the n-type window layer 121 to the p-type window layer 125 so that a predetermined region of the p-type metal layer 126 is exposed. , An LED such as (1) of FIG. 2 is manufactured.

The manufacturing method of RCLED or VCSEL shown in FIG. 2 (2) is demonstrated.

First, an n-type window layer 141, an n-type Bragg reflector layer 142, an active layer 143, a current guide layer 144, a p-type Bragg reflector layer 145, and an n-type GaAs substrate (not shown). The p-type window layer 146 is sequentially formed, and the p-type metal layer 147 is formed on the p-type window layer 146. Here, the manufacturing method of the p-n junction diode is not limited to the scope of the present invention, and all the manufacturing methods of the conventional RCLED can be used, so the detailed description thereof will be omitted. The non-conductive silicon-based adhesive 130 is applied to the p-type substrate 111 having a higher thermal conductivity than GaAs by a spin coating method.

As described in the manufacturing method of the LED shown in FIG. 2 (1), after the substrate bonding of the p-type metal layer 147 and the p-type substrate 111 is performed, the n-type GaAs substrate is removed and the exposed n-type The n-type metal layer 148 is in ohmic contact with a predetermined region of the window layer 141, and the p-type window layer 146 is provided from the n-type window layer 141 so that the predetermined region of the p-type window layer 146 is exposed. When a predetermined region of each thin film is etched and the p-type metal layer 147 'is deposited on the exposed p-type window layer 146 to form a p-type electrode, an LED as shown in FIG. do.

The LEDs shown in FIG. 3 are schematic diagrams showing an inverted shape of the LEDs shown in FIG. 2. That is, the n-type substrate 112 is used as the substrate having high thermal conductivity, and the pn junction diodes shown in FIG. 2 and the pn junction diodes 120 and 140 in the reverse phase form are connected to the n-type substrate described above. will be. Therefore, repeated description is omitted. However, since a separate support substrate is further used to manufacture such a reversed phase type LED, a method of manufacturing the LED shown in FIG. 3 (1) will be described with reference to only the LED shown in FIG.

Example 2

Referring to FIG. 3 (1), first, an n-type window layer 121, an n-type cladding layer 122, an active layer 123, and a p-type cladding layer 124 are disposed on an n-type GaAs substrate (not shown). And the p-type window layer 125 are sequentially formed, the p-type metal layer 126 is formed in a predetermined region of the p-type window layer 125, and then a support substrate provided separately from the p-type metal layer 126 (not shown). ). The adhesive 130 is applied to the n-type substrate 112 having higher thermal conductivity than GaAs.

Next, the n-type GaAs substrate is removed, thereby depositing the n-type metal layer 127 on the exposed n-type window layer 121.

Next, the n-type metal layer 127 is brought into contact with the applied contact agent 130, and the n-type metal layer 127 and n-type, each of which is applied as a bonding medium layer by applying a constant pressure under a predetermined temperature, are applied. Substrate bonding of the board | substrate 112 is performed.

Subsequently, the support substrate is removed.

Then, by forming an n-type electrode for applying a current by etching a predetermined region of each thin film from the p-type window layer 125 to the n-type window layer 121 so that a predetermined region of the n-type metal layer 127 is exposed. , An LED as shown in FIG. 3 (1) is manufactured.

As described above, the light emitting device and the method of manufacturing the same according to the present invention have an advantage of effectively dissipating heat generated in the light emitting device, thereby improving reliability, for example, improving the lifespan and electro-optical characteristics of the device, and having a low thermal conductivity substrate. The light output efficiency is higher than when using.

In addition, when the non-conductive silicone-based adhesive is applied by using the rotary coating method, the process is easier than the case using the chemical vapor deposition method, and the production cost is low, and thus there is an advantage of having high productivity.

Furthermore, when the bonding medium layer is formed by using chemical vapor deposition, there is an advantage of improving thermal conductivity.

The present invention is not limited to the above embodiments, and it is apparent that many modifications are possible by those skilled in the art within the technical spirit of the present invention.

1A to 1C are schematic views showing the structure of a conventional light emitting diode; And

2 and 3 are schematic diagrams for explaining embodiments of the present invention.

<Description of Reference Numbers for Main Parts of Drawings>

111, 112: Substrate

120, 140: p-n junction diode

130: non-conductive silicone adhesive

Claims (16)

A substrate having a higher thermal conductivity than GaAs; a p-n junction diode; And a junction media layer applied on the substrate to bond the substrate to the p-n junction diode. The light emitting device of claim 1, wherein the p-n junction diode is made of a GaAs / AlGaAs-based or InGaP / AlGaInP-based material. The light emitting device of claim 1, wherein the substrate is made of Si, AlN, SiC, CuW, Cu, or Al. The light emitting device of claim 1, wherein the bonding medium layer is formed of a non-conductive silicon-based adhesive applied on the substrate by a rotation coating method. 5. A light emitting device according to claim 4 wherein the adhesive is SOG or glass frit. 6. The light emitting device according to claim 4 or 5, wherein the adhesive is applied in a thickness of 100 µm to 5 µm. The light emitting device of claim 1, wherein the bonding medium layer is formed of a dielectric film having a thickness of 50 kV to 3000 kPa that is deposited on the substrate by chemical vapor deposition. 8. The light emitting device of claim 7, wherein the dielectric film is made of SiO ₂ or SiN. The pn junction diode of claim 1, wherein the pn junction diode comprises a p-type metal layer, a p-type window layer, a p-type cladding layer, an active layer, an n-type cladding layer, an n-type window layer, and an n-type metal layer. Is a vertical resonance light emitting diode comprising a p-type metal layer, a p-type window layer, a p-type Bragg reflector layer, a current guide layer, an active layer, an n-type Bragg reflector layer, an n-type window layer, and an n-type metal layer, or a vertical resonance surface A light emitting laser diode; And the p-n junction diode and the p-type substrate are bonded by the junction media layer so that the junction media layer is positioned between the p-type metal layer and the p-type substrate if the substrate is a p-type substrate. The pn junction diode of claim 1, wherein the pn junction diode comprises a p-type metal layer, a p-type window layer, a p-type cladding layer, an active layer, an n-type cladding layer, an n-type window layer, and an n-type metal layer. Is a vertical resonance light emitting diode comprising a p-type metal layer, a p-type window layer, a p-type Bragg reflector layer, a current guide layer, an active layer, an n-type Bragg reflector layer, an n-type window layer, and an n-type metal layer, or a vertical resonance surface A light emitting laser diode; And the p-n junction diode and the n-type substrate are bonded by the junction media layer so that the junction media layer is positioned between the n-type metal layer and the n-type substrate when the substrate is an n-type substrate. The method of manufacturing a light emitting device according to claim 9, The n-type window layer, the n-type cladding layer, the active layer, the p-type cladding layer, the p-type window layer, and the p-type metal layer are sequentially formed on the n-type GaAs substrate, or the n-type window layer and n on the n-type GaAs substrate. Sequentially forming a type Bragg reflector layer, an active layer, a current guide layer, a p-type Bragg reflector layer, a p-type window layer, and a p-type metal layer; Bonding the p-type substrate to the p-type metal layer having a higher thermal conductivity than GaAs and to which an adhesive is applied to one surface by a rotation coating method; Removing the n-type GaAs substrate; Forming an n-type metal layer in a predetermined region of the exposed n-type window layer, and forming a p-type electrode. The method of claim 11, wherein the p-type electrode, And etching a predetermined region of each of the thin films from the n-type window layer to the p-type window layer so that the predetermined region of the p-type metal layer is exposed. The method of claim 11, wherein the p-type electrode, By etching a predetermined region of each of the thin films from the n-type window layer to the p-type window layer to expose a predetermined region of the p-type window layer, and depositing a separate p-type metal layer on the exposed p-type window layer Forming a light emitting device characterized in that it is formed. The method of manufacturing a light emitting device according to claim 10, An n-type window layer, an n-type cladding layer, an active layer, a p-type cladding layer and a p-type window layer are sequentially formed on an n-type GaAs substrate, and a p-type metal layer is formed in a predetermined region of the p-type window layer, or n-type An n-type window layer, an n-type Bragg reflector layer, an active layer, a current guide layer, a p-type Bragg reflector layer, and a p-type window layer are sequentially formed on a GaAs substrate, and a p-type metal layer is formed in a predetermined region of the p-type window layer. Steps; Bonding the support substrate provided separately from the p-type metal layer; Removing the n-type GaAs substrate; Forming an n-type metal layer on the exposed n-type window layer; Bonding the n-type substrate and the n-type metal layer to which the thermal conductivity is higher than that of GaAs and to which an adhesive is applied to one surface by a rotation coating method; Removing the support substrate; A method of manufacturing a light emitting device comprising the step of forming an n-type electrode. The method of claim 14, wherein the n-type electrode, And etching a predetermined region of each of the thin films from the p-type window layer to the n-type window layer so that a predetermined region of the n-type metal layer is exposed. The method of claim 14, wherein the n-type electrode, By etching a predetermined region of each of the thin films from the p-type window layer to the n-type window layer to expose a predetermined region of the n-type window layer, and depositing a separate n-type metal layer on the exposed n-type window layer Forming a light emitting device characterized in that it is formed.