KR100564303B1 - Light emitting diode and fabrication method thereof - Google Patents

Abstract

An AlGaInP-based light emitting diode and a manufacturing method thereof are disclosed. A light emitting diode according to the present invention comprises a p-type transparent substrate; a p-type electrode formed under the p-type transparent substrate; and 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 electrode, which are sequentially formed on the p-type transparent substrate. And the p-type window layer are bonded by substrate fusion. According to the present invention, the light output efficiency is higher than when using the absorbent substrate, the resistance after substrate fusion can be reduced than when using the n-type transparent substrate, the bonding of the transparent substrate and the removal of the absorbent substrate are easy, and the process Can reduce productivity and increase productivity.

AlGaInP-based light emitting diode, absorbent substrate, transparent substrate, substrate fusion, eutectic metal

Description

Light emitting diode and fabrication method             

1A-1C are schematic views showing a conventional light emitting diode;

2 is a schematic diagram illustrating an LED according to an embodiment of the present invention;

3 is a schematic view for explaining a method of manufacturing an LED according to FIG. And

4A and 4B are schematic diagrams for describing a packaging structure of an LED according to an embodiment of the present invention.

<Description of Reference Numbers for Main Parts of Drawings>

[Private Technology]

11 n-type GaAs substrate 12 Bragg reflector

13: n-type cladding layer 14: active layer

15 p-type cladding layer 16 p-type electrode

18: n-type electrode 19: n-type window layer

21: n-type transparent substrate 22: adhesive

[Invention]

110: p-type transparent substrate 120: p-type window layer

130: p-type cladding layer 140: active layer

150: n-type cladding layer 160: n-type window layer

170: n-type electrode 180: p-type electrode

210: eutectic metal layer 220: sub-mount

The present invention relates to an AlGaInP-based light emitting diode and a method for manufacturing the same, and more particularly, to an AlGaInP-based light emitting diode using a p-type transparent substrate and substrate fusion.

Light emitting diodes (hereinafter referred to as LEDs) are used in various applications such as display, communication, and lighting. However, when the LED layers are grown on the absorbent substrate, they exhibit low light extraction efficiency, and when grown on the transparent substrate, lattice mismatch due to lattice constant occurs.

1A is a schematic diagram illustrating a double heterojunction (DH) LED formed on a conventional absorbent substrate.

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

In this case, by forming the Bragg reflector and the standard LED growth layer sequentially on the absorbent substrate, the Bragg reflector reflects the light emitted under the light emitting active layer, thereby reducing the influence of the absorbent substrate and improving the light extraction efficiency. However, since the reflection is reflected by the Bragg reflector only when the angle of incidence is nearly perpendicular, the effect is small.

Thus, attempts have been made to replace the substrate with a transparent substrate, a representative method of which is shown in FIGS. 1B and 1C.

1B and 1C are schematic diagrams showing LEDs formed on a conventional transparent substrate. In this case, since the same reference numerals as in FIG. 1A represent the same configuration, repeated descriptions thereof will be omitted.

Referring to FIG. 1B, the p-type window layer 16 is adhered to the transparent substrate 21 such as sapphire using a transparent and adhesive adhesive 22 such as SOG (Spin-On Glass).

In this case, the light output efficiency is increased by adopting a substrate having high light transmittance, but since sapphire is a transparent substrate having no conductivity, both electrodes of p-type and n-type are disposed on the light emitting surface, which leads to a high light loss. .

1C, the n-type transparent substrate 21 (n-type GaP substrate) having a thickness of about 200 μm and the n-type GaAs substrate 11 and the Bragg reflector 12 of FIG. 1A are removed. After the n-type cladding layer 13 of the growth layer having been removed) was bonded using a graphite member (not shown), the substrate was fused in a furnace tube. The conditions at this time are carried out in a hydrogen atmosphere at a temperature of 800 ° C. and a pressure of 2 to 8 kg / cm 2 for 0.5 to 1 hour.

In this case, however, the growth layer has a thickness of about 10 μm, and there is a risk of cracking or cracking. Therefore, in the case of FIG. 1C, the thickness of the p-type window layer 16 should be about 50 to 100 μm. However, in order to grow the p-type window layer by the thickness using the organic metal chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE) used to grow the other active layer region Will take several tens of hours, resulting in low productivity. Therefore, only the p-type window layer 16 is grown using vapor phase epitaxy (VPE), which has a relatively high growth rate. There is a hassle to precede.

Accordingly, an object of the present invention is to provide an AlGaInP-based light emitting diode having high light output efficiency, simplifying a manufacturing process, preventing short circuit, and improving heat dissipation, so that a light emitting device having a large output can be manufactured. And to provide a method for producing the same.

AlGaInP-based light emitting diode according to the present invention for achieving the above technical problem: a p-type transparent substrate having a thickness of 50 ~ 350㎛; A p-type electrode formed under the p-type transparent substrate; A p-type window layer, a p-type cladding layer, an active layer, an n-type cladding layer, and an n-type window layer sequentially formed on the p-type transparent substrate; A eutectic metal layer formed on the n-type window layer; A submount layer formed on the eutectic metal layer; And an n-type electrode formed on the submount layer.

At this time, the p-type transparent substrate and the p-type window layer is characterized in that the bonding by substrate fusion.

AlGaInP-based light emitting diode manufacturing method according to the present invention for achieving the above technical problem: the n-type window layer, n-type cladding layer, active layer, p-type cladding layer and p-type window layer sequentially on the n-type GaAs substrate Forming; Bonding the p-type window layer and the p-type transparent substrate having a thickness of 50 to 350 μm by substrate fusion; Removing the n-type GaAs substrate; Forming the p-type electrode on the p-type transparent substrate; Inverting the result to the step, characterized in that it comprises the step of sequentially forming the eutectic metal layer, the sub-mount layer and the n-type electrode on the n-type window layer.

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

2 is a schematic view showing an LED according to an embodiment of the present invention, Figure 3 is a schematic diagram for explaining a manufacturing method of the LED according to Figure 2, Figure 4a and 4b is a packaging of the LED according to an embodiment of the present invention Schematic diagrams for explaining the structure.

2, an LED according to an embodiment of the present invention includes a p-type transparent substrate 110, a p-type electrode 180 formed below the p-type transparent substrate 110, and a p-type transparent substrate 110. P-type window layer 120, p-type cladding layer 130, active layer 140, n-type cladding layer 150, n-type window layer 160, and n-type electrode 170 sequentially formed on the It is made, including. The p-type transparent substrate 110 is made of GaP, ZnSe or ZnS, and has a thickness of 50 to 350 µm. The p-type window layer 120, the p-type cladding layer 130, the active layer 140, the n-type cladding layer 150, and the n-type window layer 160 are made of AlGaInP-based material. The p-type electrode 180 may be made of Ti / Au, Ti / Pt / Ti / Au, AuBe, or the like, and the n-type electrode 170 may be made of AuGe / Ni / Au.

The p-type transparent substrate 110 and the p-type window layer 120 are bonded by direct wafer bonding. Substrate fusion will be described later.

The p-type window layer transmits output light and increases current spreading. When the current is diffused in the p-type window layer 120 and the holes of the p-type cladding layer 130 and the electrons of the n-type cladding layer 150 are combined in the active layer 140, photons having a wavelength according to an energy band gap are formed. Will be generated. As described above, since the p-type window layer 120 is bonded by the p-type transparent substrate 110 and the substrate fusion, the diffusion of the current in the p-type window layer 120 is not a current diffusion by the metal pattern, but p The diffusion does not need to be thick due to the current applied from the type transparent substrate 110.

Hereinafter, with reference to FIG. 3, the LED manufacturing method according to the embodiment of the present invention using the substrate fusion will be described.

First, as shown in FIG. 3 (1), an n-type window layer 160, an n-type cladding layer 150, an active layer 140, a p-type cladding layer 130, and p are formed on the n-type GaAs substrate 11. The window window layer 120 is sequentially formed.

Then, TCE, acetone, methanol, or the like is added to the surface of the p-type GaP substrate 110 having a thickness of 50 to 350 μm formed separately from the surface of the p-type window layer 120 to remove organic matter, and the oxide film on the surface using HF diluent. Remove it.

Next, as shown in FIG. 3 (2), the p-type window layer 120 and the p-type GaP substrate 110 are bonded using a graphite member (not shown), and then the substrate is fused in a hydrogen atmosphere. At this time, the process temperature is 650 ~ 900 ℃, the pressure is 1/8 kg / cm 2, the time is 0.5 to 1 hour.

Next, as shown in FIG. 3 (3), the GaAs substrate 11 is removed by wet or dry etching.

Subsequently, as shown in FIG. 3 (4), the above-described p-type metal 180 is deposited on the p-type GaP substrate 110, and the above-described n-type metal 170 is deposited on the n-type window layer 160. By ohmic contact to manufacture an LED according to an embodiment of the present invention. For reference, the LED shown in FIG. 2 is a reversed phase structure of the LED shown in FIG. 3 (4), and the contents of the present invention are not changed, but only according to the packaging structure of the LED according to the embodiment of the present invention described later. It's different.

Thus, by bonding the p-type transparent substrate and the p-type window layer through the substrate fusion, conductivity is imparted to the p-type transparent substrate, and the p-type transparent substrate functions as a supporting wafer during epitaxy after removing the GaAs substrate. Done. Therefore, the transparent substrate can be easily bonded and the absorbent substrate can be removed, and the LED of high light output efficiency can be manufactured.

On the other hand, a thin p-type InGaP layer of 50 nm or less may be further formed on the surface of the p-type window layer bonded to the transparent substrate for ease of substrate fusion. Since the added p-type InGaP layer is thin, it shows a good resistance characteristic for fusion of the p-type GaP substrate and the p-type window layer with little effect on the light output. layer).

In general, when the n-type window layer of the manufactured LED is bonded downward to the package submount, the metal epoxy is applied to the thin n-type window layer, so that the metal epoxy is also applied to the side of the n-type window layer. The problem of short circuiting of the active region may occur. The packaging structure of the LED according to the present invention that can solve this problem will be described.

In the reversed phase structure in which light is emitted toward the n-type electrode as shown in FIG. 2, the n-type electrode 170 is formed to be positioned in a predetermined region of the n-type window layer 160, and the p-type electrode 180 is It is formed to be located on the entire surface of the p-type transparent substrate (110). In this case, since the thickness of the transparent substrate 110 is 50 to 350 μm, the metal epoxy is prevented from being applied to the active layer 140, and a short circuit does not occur.

Next, a description will be given with reference to FIGS. 4A and 4B in the case of the general form in which the n-type window layer is coupled to the submount with the downward direction. In this case, the n-type electrode 170 is formed to be positioned on the entire surface of the n-type window layer 160, and the p-type electrode 180 is formed to be positioned in a predetermined region of the p-type transparent substrate 110. .

Referring to FIG. 4A, the eutectic metal layer 210 and the submount 220 are n-type window layers by metal bonding the sub-mount layer with the n-type window layer using a low melting eutectic metal. It becomes a structure interposed between the 160 and the n-type electrode 170 sequentially. Si, SiC, Cu, CuW, or T-CBN may be used as the sub-mount 220, and Au-Sn, Au-Ge, Ag-In series may be used as the eutectic metal. At this time, the eutectic metal and the submount may be bonded to each other by applying a temperature to the n-type window layer, or the eutectic metal may be deposited on the n-type window layer and then the submount may be heated and bonded to the eutectic metal. In this way, the eutectic metal layer 210 and the sub-mount 220 are interposed between the n-type window layer 160 and the n-type electrode 170 to generate a high output large area light emitting device. It is possible to release sufficient thermal energy.

Referring to FIG. 4B, a eutectic metal layer 210 is formed on the n-type electrode 170. Thus, by directly depositing the eutectic metal on the n-type electrode, it is possible to easily bond the LED chip manufactured to the sub-mount heated to a constant temperature without the metal epoxy.

As described above, according to the AlGaInP-based light emitting diode according to the present invention, by using a p-type transparent substrate, the light output efficiency is higher than when using an absorbent substrate.

In addition, since the diffusion rate of the p-type dopant is faster than the diffusion rate of the n-type dopant, the resistance after substrate fusion can be reduced than when using the n-type transparent substrate.

Furthermore, by bonding the p-type transparent substrate and the p-type window layer through substrate fusion, the GaAs substrate is removed, thereby facilitating the bonding of the transparent substrate and the removal of the absorbent substrate and reducing the risk of the process, thereby improving productivity.
Furthermore, the short circuit is prevented and the heat dissipation effect is improved to manufacture a light emitting device having a high output large area.

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.

Claims (8)

A p-type transparent substrate having a thickness of 50 to 350 µm; A p-type electrode formed under the p-type transparent substrate; A p-type window layer, a p-type cladding layer, an active layer, an n-type cladding layer, and an n-type window layer sequentially formed on the p-type transparent substrate; A eutectic metal layer formed on the n-type window layer; A submount layer formed on the eutectic metal layer; An AlGaInP-based light emitting diode comprising an n-type electrode formed on the sub-mount layer. The AlGaInP-based light emitting diode of claim 1, wherein the p-type transparent substrate is made of GaP, ZnSe, or ZnS. delete The AlGaInP-based light emitting diode of claim 1, wherein the p-type window layer, the p-type cladding layer, the active layer, the n-type cladding layer, and the n-type window layer are made of AlGaInP. The AlGaInP-based light emitting diode according to any one of claims 1 to 6, wherein the p-type transparent substrate and the p-type window layer are bonded by substrate fusion. delete delete The method of manufacturing an AlGaInP-based light emitting diode according to claim 5, sequentially forming the n-type window layer, n-type cladding layer, active layer, p-type cladding layer and p-type window layer on an n-type GaAs substrate; Bonding the p-type window layer and the p-type transparent substrate having a thickness of 50 to 350 μm by substrate fusion; Removing the n-type GaAs substrate; Forming the p-type electrode on the p-type transparent substrate; Inverting the result up to the step, and forming the eutectic metal layer, the sub-mount layer and the n-type electrode sequentially on the n-type window layer, characterized in that the AlGaInP-based light emitting diode manufacturing method.

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