KR100730755B1 - Method for fabricating a vertical light emitting device and vertical light emitting device thereby - Google Patents

Abstract

A method for manufacturing a vertical type light emitting device and the vertical type light emitting device are provided to prevent bending of a compound semiconductor layer by using a conductive substrate having an unevenness with a transparent conductive film. A substrate(100) is prepared. A compound semiconductor layer comprised of a first conductive semiconductor layer(410), an active layer(420), and a second conductive semiconductor layer(430) is formed on the substrate. A transparent conductive film is deposited on the unevenness surface of the substrate to configure a conductive substrate. The conductive substrate is bonded on the second conductor semiconductor layer. A laser is irradiated to the conductive substrate to separate the conductive substrate from the compound semiconductor layer.

Description

Method for manufacturing vertical light emitting device and vertical light emitting device therefor {METHOD FOR FABRICATING A VERTICAL LIGHT EMITTING DEVICE AND VERTICAL LIGHT EMITTING DEVICE THEREBY}

1 and 2 are cross-sectional views illustrating a manufacturing process of a conventional vertical light emitting device.

3 is a process flowchart illustrating a manufacturing process of a vertical light emitting device according to an embodiment of the present invention.

4 to 6 are cross-sectional views of the manufacturing process of FIG. 3.

The present invention relates to the manufacture of a vertical light emitting device, and more particularly, to form a p-type conductive substrate having irregularities formed on a p-type semiconductor layer when manufacturing a vertical light emitting device, and a vertical light emitting device having improved light extraction efficiency and the same. It relates to a manufacturing method.

Group III-V compound semiconductors provide superior performance in applications such as high speed and high temperature electronics, light emitters and light detectors. In particular, gallium nitride (GaN) included in nitride compound semiconductors has a bandgap required for a blue laser and a light emitting diode emitting a blue wavelength spectrum. Doing. In addition, alloys of aluminum nitride (AlN), indium nitride (InN), and gallium nitride (GaN) are used in various light emitting devices by providing a spectrum over the entire visible region.

In general, a light emitting device includes a light emitting diode having a first conductive semiconductor layer, a second conductive semiconductor layer, and an active layer interposed between these semiconductor layers. Light is generated by the recombination of electrons and holes in the active layer and emitted to the outside.

Recently, vertical LEDs have been disclosed to shorten the recombination distance between electrons and holes to reduce energy loss in light emitting diodes.

Conventionally, in order to fabricate such a vertical light emitting device, a buffer layer 2, an undoped semiconductor layer 3, a first semiconductor layer 4, an active layer 5, and a first layer are formed on a substrate 1 as shown in FIG. 2, the semiconductor layer 6, the transparent electrode, or the metal 7 are sequentially formed, and then the buffer layer is decomposed by irradiating a laser onto the substrate by a laser lift off (LLO) technique as shown in FIG. 2. ), And electrodes are formed in the first semiconductor layer and the second semiconductor layer, respectively.

However, after the laser lift off (LLO) process, as shown in FIG. 2, the semiconductor layer may be bent due to a difference in lattice constant and thermal expansion coefficient between layers.

An object of the present invention is to prevent the bending of the semiconductor layer when separating the substrate in the conventional manufacturing of the vertical light emitting device, and to improve the light extraction rate.

According to an aspect of the present invention for achieving the above technical problem, a step of preparing a substrate, forming a compound semiconductor layer consisting of a first conductive semiconductor layer, an active layer and a second conductive semiconductor layer on the substrate, and one surface Bonding a conductive substrate on which the unevenness is formed and a transparent conductive film is deposited on the uneven surface on the second conductive semiconductor layer, and separating the substrate from the compound semiconductor layer by irradiating a laser to the substrate. It provides a vertical light emitting device manufacturing method characterized in that.

Bonding the conductive substrate may include preparing a conductive substrate having a pattern of irregularities, depositing and flattening the transparent conductive film on a surface on which the pattern of irregularities is formed, and a surface on which the pattern is formed on the second surface. Bonding to contact the conductive semiconductor layer.

Bonding the conductive substrate may include preparing a conductive substrate having a rough surface, depositing and flattening the transparent conductive film on the rough surface of the conductive substrate, and wherein the rough surface is the second conductive semiconductor. Bonding to abut the layer.

The conductive substrate may be a p-type Si substrate.

According to another aspect of the present invention, a compound semiconductor layer comprising a substrate, a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer sequentially stacked on the substrate, and irregularities are formed on one surface, and a transparent conductive film is deposited on the irregularities. And a conductive substrate bonded on the second conductive semiconductor layer, and an electrode formed on the first conductive semiconductor layer exposed by separating the substrate from the compound semiconductor layer by irradiating a laser to the substrate. do.

The conductive substrate may have a pattern of concave-convex, and may be bonded to contact the second conductive semiconductor layer after the transparent conductive film is deposited on the surface on which the concave-convex pattern is formed to be flat. .

The conductive substrate may have a rough surface, and the transparent conductive film may be deposited on the rough surface to be flattened, and then the rough surface may be bonded to contact the second conductive semiconductor layer.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided as examples to ensure that the spirit of the invention to those skilled in the art will fully convey. Accordingly, the invention is not limited to the embodiments described below and may be embodied in other forms. In the drawings, lengths, thicknesses, and the like of layers and regions may be exaggerated for convenience. Like numbers refer to like elements throughout.

3 is a flowchart illustrating a manufacturing process of a vertical light emitting device according to an exemplary embodiment of the present invention, and FIGS. 4 to 6 are cross-sectional views illustrating a manufacturing process thereof. Here, the manufacturing process of the nitride semiconductor device among the vertical light emitting devices will be described.

3 and 4, a substrate 100 is prepared in a process chamber (not shown) for forming a nitride semiconductor layer (S1). The substrate 100 has a lattice constant similar to that of the nitride semiconductor layer to be formed thereon.

For example, sapphire (Al2O3), silicon (Si), spinel, silicon carbide (SiC), zinc oxide (ZnO), gallium arsenide (GaAs), gallium phosphorus (GaP), lithium-alumina (LiAl2O3), It may be a boron nitride (BN), aluminum nitride (AlN), or gallium nitride (GaN) substrate, and may be selected according to the material of the semiconductor layer to be formed on the substrate 100. In the case of forming a gallium nitride-based semiconductor layer, a sapphire or silicon carbide (SiC) substrate is mainly used as the substrate.

Thereafter, the buffer layer 200 is formed on the substrate 100 (S2).

The buffer layer 200 is used to mitigate the lattice mismatch between the semiconductor layers to be formed thereon and the substrate 100. The buffer layer 200 may be, for example, an AlN or GaN layer and may be grown to a thickness of 20 nm to 50 nm at a low temperature, for example, at a temperature of about 400 to about 700 ° C. and a pressure of 50 Torr to 700 Torr.

Thereafter, an undoped GaN semiconductor layer 300 is formed on the buffer layer 200 (S3).

The undoped GaN semiconductor layer 300 is interposed between the buffer layer 200 and the first conductive semiconductor layer 410 and is made of undoped GaN.

The undoped GaN semiconductor layer 300 provides a high quality GaN semiconductor layer so that the first conductive semiconductor layer 410 made of a GaN based material can be effectively formed at a high quality.

The buffer layer 200 and the undoped GaN semiconductor layer 300 may include metal organic chemical vapor deposition (MOCVD), hydride vapor phase epitaxy (HVPE), or molecular beam epitaxy. , MBE) and the like.

Referring to FIGS. 3 and 5, the compound semiconductor layer 400 including the first conductive semiconductor layer 410, the active layer 420, and the second conductive semiconductor layer 430 is disposed on the undoped GaN semiconductor layer 300. To form sequentially (S4).

The first conductive semiconductor layer 410 may be formed of N-type _{Al x In y Ga 1 -x- y} N (0≤x, y, x + y≤1), may include a N-type clad layer . The first conductive semiconductor layer 410 may be formed by doping silicon (Si).

The active layer 420 is an area where electrons and holes are recombined and includes InGaN. The emission wavelength emitted from the light emitting diode is determined by the type of material constituting the active layer 420. The active layer 420 may be a multilayer film in which a quantum well layer and a barrier layer are repeatedly formed. The barrier layer and the well layer may be a layer 2 table semiconductor-to 4 won compound current by the general formula _{Al x In y Ga 1 -x- y} N (0≤x, y, x + y≤1).

A second conductive semiconductor layer 430 may be formed of P-type _{Al x In y Ga 1 -x- y} N (0≤x, y, x + y≤1), may include a P-type clad layer . The second conductive semiconductor layer 430 may be formed by doping zinc (Zn) or magnesium (Mg).

Thereafter, the p-type conductive substrate 600 having unevenness is bonded to the second conductive semiconductor layer 430 by using the transparent conductive film 500 (S5).

To this end, a conductive substrate 600 having a pattern of irregularities is prepared. Then, the transparent conductive film 500 is deposited on the surface on which the uneven pattern of the conductive substrate 600 is formed to be flat. Then, bonding is performed by bringing the surface on which the flattened pattern is formed by the transparent conductive film 500 into contact with the second conductive semiconductor layer 430.

Here, indium tin oxide (ITO), ZnO, or SnO ₂ may be used as the transparent conductive film. In the case of a thin film, a metal thin film such as Ni / Au is also possible.

Unevenness is formed in a portion of the conductive substrate 600 that contacts the second conductive semiconductor layer 430. Accordingly, the light generated from the active layer 420 may be efficiently reflected and emitted to the outside through the uneven surface formed on the conductive substrate 600 without forming a separate reflecting plate. In order to form irregularities in the conductive substrate 600, an arbitrary pattern may be regularly formed on the conductive substrate 600. For example, a pattern having a triangular or convex rounded shape in cross section may be formed.

In this case, the transparent conductive film is formed between the pattern of the conductive substrate 600 and the second conductive semiconductor layer 430 in order to improve the bonding property of the conductive substrate 600 on which the pattern is formed and the second conductive semiconductor layer 430. Fill 500.

Thereafter, the laser beam is irradiated toward the substrate 100 to separate the substrate 100 (S6).

In this case, the laser is selected to have an energy smaller than the energy band gap of the substrate and to have an energy larger than the energy band gap of the buffer layer 200.

When the laser is irradiated from the substrate 100, the substrate 100 is a light transmissive substrate, and thus the buffer layer 200 is decomposed by the energy absorbed at the interface between the substrate 100 and the buffer layer 200, thereby degrading the substrate 100. Are separated. The lower surface of the separated nitride semiconductor layer 300 may be cleaned. Accordingly, separation of the substrate 100 from the compound semiconductor layer 400 is completed.

In this case, as the compound semiconductor layer 400 is bonded by the conductive substrate 600, the substrate 100 is separated without warping of the compound semiconductor layer 400.

Referring to FIGS. 3 and 6, after the substrate 100 is separated, the buffer layer 310 and the undoped GaN semiconductor layer 320 are etched to expose one surface of the first conductive semiconductor layer 330 ( S7).

Thereafter, the electrode pad 700 is formed on the exposed surface of the first conductive semiconductor layer 330 (S8). The electrode pad 700 may be formed by a lift off method.

The electrode pad 700 operates as a negative electrode, and the conductive substrate 600 operates as a positive electrode.

The invention described above is not limited to the embodiments described above, and various modifications and changes can be made by those skilled in the art, which are included in the spirit and scope of the invention as defined in the appended claims.

For example, in the exemplary embodiment of the present invention, a transparent conductive film is deposited on a p-type Si substrate on which an uneven pattern is formed to be flattened, then bonded to a second semiconductor layer, and substrate separation is performed. When the back side is used as the substrate bonding surface, a transparent conductive film is deposited on the rough back surface to be flattened without bonding a concave-convex pattern, and then bonded to the second semiconductor layer, and then the substrate is separated. Substrate separation effect and light extraction efficiency can be obtained.

According to the present invention, when fabricating a vertical light emitting device, a compound semiconductor layer comprising a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer is formed, and then a conductive substrate having irregularities formed on the second conductive semiconductor layer by using a transparent conductive film. By bonding to the substrate, when the laser is irradiated to the substrate to separate the substrate from the compound semiconductor layer, the conductive substrate bonded on the second conductive semiconductor layer supports the semiconductor layer, thereby preventing the compound semiconductor layer from bending.

In addition, as the conductive substrate bonded on the second conductive semiconductor layer has conductivity, the conductive substrate may be used as an electrode for supplying power to the conductive substrate as it is, thus eliminating the need to perform a separate process for forming an electrode. do.

In addition, the light extraction rate can be improved by efficiently reflecting the light generated from the active layer through the uneven surface formed on the conductive substrate to be emitted to the outside.

Claims (8)

Preparing a substrate; Forming a compound semiconductor layer comprising a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer on the substrate; Bonding a conductive substrate having irregularities formed on one surface and a transparent conductive film deposited on the irregular surface on the second conductive semiconductor layer; Irradiating the substrate with a laser to separate the substrate from the compound semiconductor layer. The method of claim 1, wherein the bonding of the conductive substrate, Preparing a conductive substrate having a pattern of irregularities; Depositing and flattening the transparent conductive film on a surface on which the uneven pattern is formed; And bonding the patterned surface to contact the second conductive semiconductor layer. The method of claim 1, wherein the bonding of the conductive substrate, Preparing a conductive substrate having a rough surface, Depositing and flattening the transparent conductive film on the rough surface of the conductive substrate; And bonding the rough surface to contact the second conductive semiconductor layer. The method according to claim 1, wherein the conductive substrate, A vertical light emitting device manufacturing method, characterized in that the p-type Si substrate. Substrate, A compound semiconductor layer comprising a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer sequentially stacked on the substrate; Concave and convexity is formed on one surface and a transparent conductive film is deposited on the concave and convex surface bonded to the second conductive semiconductor layer, And an electrode formed on the first conductive semiconductor layer exposed by separating the substrate from the compound semiconductor layer by irradiating a laser to the substrate. The method according to claim 5, The conductive substrate, A vertical light emitting device having a pattern of irregularities, wherein the transparent conductive film is deposited on the surface on which the pattern of irregularities is formed and processed to be flat, and then the surface on which the pattern is formed is bonded to contact the second conductive semiconductor layer. . The method according to claim 5, The conductive substrate, And having a rough surface, wherein the transparent conductive film is deposited on the rough surface to be flattened, and then the rough surface is bonded to contact the second conductive semiconductor layer. The method according to claim 5, The conductive substrate, A vertical light emitting device, characterized in that the p-type Si substrate.

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