KR20090078479A - Light emitting device having vertical structure and method for manufacturing the same - Google Patents

Abstract

A light emitting device having a vertical structure and a manufacturing method thereof are provided to prevent a lowering effect of electrical characteristics by securing coherence between an electrode and a reflective layer or between metal layers. A light emitting device having a vertical structure includes a multi-layered semiconductor layer(200), a first electrode, and metal layers(500,510). The first electrode is positioned on the semiconductor layer. The first electrode includes surface roughness or a pattern formed on the other side of the multi-layered semiconductor layer. The metal layer is positioned on the first electrode. The multi-layered semiconductor layer is formed on the substrate. The first electrode is formed on the multi-layered semiconductor layer. The pattern is formed on the first electrode. At least one or more metal layer is formed on the first electrode including the pattern. The substrate is removed. A second electrode is formed on the exposed semiconductor layer.

Description

Light emitting device having vertical structure and method for manufacturing the same

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device, and more particularly, to a vertical light emitting device capable of improving device performance, reliability, and yield of a vertical light emitting device, and a manufacturing method thereof.

Light Emitting Diodes (LEDs) are well-known semiconductor light emitting devices that convert current into light.In 1962, red LEDs using GaAsP compound semiconductors were commercialized, along with GaP: N series green LEDs. It has been used as a light source for display images of electronic devices, including.

The wavelength of light emitted by such LEDs depends on the semiconductor material used to make the LEDs. This is because the wavelength of the emitted light depends on the band-gap of the semiconductor material, which represents the energy difference between the valence band electrons and the conduction band electrons.

Gallium nitride compound semiconductors (Gallium Nitride (GaN)) have high thermal stability and wide bandgap (0.8 to 6.2 eV), which has attracted much attention in the development of high-power electronic components including LEDs.

One reason for this is that GaN can be combined with other elements (indium (In), aluminum (Al), etc.) to produce semiconductor layers that emit green, blue and white light.

In this way, the emission wavelength can be adjusted to match the material's characteristics to specific device characteristics. For example, GaN can be used to create white LEDs that can replace incandescent and blue LEDs that are beneficial for optical recording.

Due to the advantages of these GaN-based materials, the GaN-based LED market is growing rapidly. Therefore, since commercial introduction in 1994, GaN-based optoelectronic device technology has rapidly developed.

The brightness or output of the LED using the GaN-based material as described above is large, the structure of the active layer, the light extraction efficiency to extract light to the outside, the size of the LED chip, the type and angle of the mold (mold) when assembling the lamp package , Fluorescent material and the like.

The technical problem to be achieved by the present invention is to provide a vertical light emitting device and a method of manufacturing the same, which can be expected to increase the light extraction efficiency while improving the electrical properties by securing the bonding force between the electrode and the reflective film in the structure of the vertical light emitting device. To provide.

As a first aspect for achieving the above technical problem, the present invention provides a vertical light emitting device comprising: a semiconductor layer having a multilayer structure; A first electrode disposed on the semiconductor layer and having a surface roughness or a pattern formed on the other side of the semiconductor layer; It characterized in that it comprises a metal layer located on the first electrode.

As a 2nd viewpoint for achieving the said technical subject, this invention is a support layer; A reflective layer on the support layer; A first electrode on the reflective layer; A semiconductor layer having a multilayer structure positioned on the first electrode; And a second electrode disposed on the semiconductor layer, wherein a pattern is formed on a contact surface of the reflective layer and the first electrode.

As a third aspect for achieving the above technical problem, the present invention comprises the steps of forming a semiconductor layer of a multi-layer structure on a substrate; Forming a first electrode on the semiconductor layer; Forming a pattern on the first electrode; Forming at least one metal layer on the first electrode on which the pattern is formed; Removing the substrate; And removing the substrate to form a second electrode on the exposed semiconductor layer.

The present invention can secure the bonding force between the electrode and the reflective film or other metal layer of the vertical light emitting device, and can prevent the deterioration of the electrical properties in the structure consisting of several metal layers, and increase the light extraction efficiency along with securing the bonding force. Therefore, it is not necessary to form a light extraction structure such as a separate photonic crystal in the semiconductor layer, and the reduction of this process can prevent the damage caused in the process of forming the light extraction structure in the semiconductor layer, and the reduction of the process This leads to improved reliability and reduced costs. As a result, the performance and reliability of the device can be improved, and ultimately, there is an effect that can solve the decrease in device yield.

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

While the invention allows for various modifications and variations, specific embodiments thereof are illustrated by way of example in the drawings and will be described in detail below. However, it is not intended to be exhaustive or to limit the invention to the precise forms disclosed, but rather the invention includes all modifications, equivalents, and alternatives consistent with the spirit of the invention as defined by the claims.

When an element such as a layer, region or substrate is referred to as being on another component "on", it will be understood that it may be directly on another element or there may be an intermediate element in between. . If a part of a component, such as a surface, is expressed as 'inner', it will be understood that this means that it is farther from the outside of the device than other parts of the element.

Furthermore, relative terms such as "beneath" or "overlies" refer to the relationship of one layer or region to one layer or region and another layer or region with respect to the substrate or reference layer, as shown in the figures. Can be used to describe.

It will be understood that these terms are intended to include other directions of the device in addition to the direction depicted in the figures. Finally, the term 'directly' means that there is no element in between. As used herein, the term 'and / or' includes any and all combinations of one or more of the recorded related items.

Although the terms first, second, etc. may be used to describe various elements, components, regions, layers, and / or regions, such elements, components, regions, layers, and / or regions It will be understood that it should not be limited by these terms.

Embodiments of the present invention will be described with reference to a gallium nitride (GaN) based light emitting device formed on a nonconductive substrate such as, for example, a sapphire (Al ₂ O ₃ ) based substrate. However, the present invention is not limited to this structure.

Embodiments of the invention may use other substrates, including conductive substrates. Thus, combinations of AlGaInP diodes on GaP substrates, GaN diodes on SiC substrates, SiC diodes on SiC substrates, SiC diodes on sapphire substrates, and / or GaN, SiC, AlN, ZnO and / or nitride based diodes on other substrates may be included. have. Moreover, the present invention is not limited to the use of the diode region. Other forms of active area may also be used in accordance with some embodiments of the present invention.

First Embodiment

The structure of the gallium nitride series (AlInGaN) light emitting device is limited to a horizontal structure and a vertical structure. Among these, the horizontal light emitting device has a limitation in increasing the light emitting efficiency structurally, and is not suitable for manufacturing high brightness light emitting devices. In contrast, in the vertical light emitting device, since both electrodes are positioned at the upper and lower ends of the device, current flows in one direction, and thus the light emitting efficiency of the vertical light emitting device can be structurally increased compared to the horizontal light emitting device.

1 illustrates an example of a vertical light emitting device, wherein metal layers 30 and 31 are positioned on a support layer 40, and first electrode layers 20, 21, and 22 having a multilayer structure are disposed on the metal layers 30 and 31. The semiconductor layer 10 and the second electrode 50 are positioned on the electrode layers 20, 21, 22.

In this case, the first electrode layer may form an ohmic contact, and the ohmic contact may form the ohmic electrode 20 on the surface of the semiconductor layer 10 using a transparent material such as indium tin oxide (ITO). After deposition on it is secured by heat treatment. Thereafter, a silver-based reflecting film 22 is formed on the ohmic electrode 20 in order to prevent loss of light emitted to the ohmic electrode 20 and to increase light extraction efficiency.

However, since Ag has a poor adhesion to a film such as an oxide, an insertion layer 21 is inserted into an interface between the reflective film 22 and the transparent electrode 20. Nickel (Ni), tungsten (W) and the like are usually used as the bonding layer 21, and the thickness thereof is limited to several to several tens of microwatts so as not to lower the reflectance of the reflective film 22.

However, such a thin coupling layer 21 is difficult to maintain in a continuous (uniform) thin film form, it can bring a large deviation between processes.

That is, after forming ohmic contact with a material such as ITO at the time of forming the ohmic electrode 20, a bonding layer 21 such as Ni and W was deposited to a thickness of several tens of microseconds. The bonding layer 21 is thin as described above to minimize the light loss caused by the opaque metal layer during operation of the light emitting device while the ITO forming the reflective film 22 such as Ag and Al and the ohmic electrode 20 has sufficient bonding strength. Deposited to thickness.

However, the metal layer forming the bonding layer 21 is difficult to be deposited in a layer-by-layer structure as expected when deposited in a vacuum chamber. In particular, while metals are deposited on oxide films, they have a strong tendency to merge with each other to reduce interfacial energy through surface migration or diffusion.

As such, the discontinuous coupling layer 21 may cause a loss in the expected coupling force by bringing a substantial portion of the surface of the ohmic electrode 20 into direct contact with the reflective layer 22.

In the case of the vertical light emitting device, when the wafer unit process is completed, the vertical light emitting device must be divided by a process of separating each individual light emitting device. In this process, excessive tensile stress may be applied to the quality of the reflective film 22, and due to the interfacial bonding force between the insufficient reflective film 22 and the ohmic electrode 20 described above, immediate or time-dependent peeling may occur. This may bring about a decrease in the electrical characteristics of the vertical light emitting device as well as the coupling of the reflective film 22 and the transparent electrode 20.

Second Embodiment

Hereinafter, an embodiment of a light emitting device having an electrode structure capable of greatly improving the bonding force between the ohmic electrode and the reflective film will be described.

First, as shown in FIG. 2, the semiconductor layer 200 having a multilayer structure is formed on the substrate 100. The semiconductor layer 200, the n-type semiconductor layer 210, the active layer 220, and the p-type semiconductor layer 230 may be sequentially disposed.

3, the p-type electrode 300 is formed on the semiconductor layer 200 using a metal or a transparent conductive oxide, and the upper surface of the p-type electrode 300 has a specific pattern 310. Is patterned to have Such patterning may be formed through various methods such as etching and lithography. In this case, the pattern 310 may be a photonic crystal pattern having a periodicity, or may be a random structure having a predetermined limit in which an average distance between the unit structures of each pattern 310 is defined.

Next, as shown in FIG. 4, the metal of the reflective layer 400 is deposited on the surface on which the above-described pattern 310 of the p-type electrode 300 is formed.

That is, the above-described pattern 310 on the p-type electrode 300 may serve as a photonic crystal to effectively extract light generated from the semiconductor layer 200, and at the same time, the p-type electrode 300 By allowing the reflective layer 400 to be firmly coupled on the top surface, the coupling force between the p-type electrode 300 and the reflective layer 400 may be increased.

Therefore, even if the photonic crystal pattern is not formed on the semiconductor layer 200 later, sufficient light extraction effect can be brought about, and physical and chemical damage of the semiconductor layer 200 that can be applied in the process of forming the pattern on the semiconductor layer 200. Can be prevented.

The adhesion between the p-type electrode 300 and the reflective layer 400 may be increased or decreased depending on the height and width of the surface structure of the pattern 310, but the reflective layer 400 may be a p-type electrode ( As long as the surface roughness can be conformally deposited on the surface of the substrate 300, the bonding force may increase.

Thus, the increase in the bonding force due to the change in the surface morphology of the p-type electrode 300 may be more effective than that due to the adhesion layer.

Thereafter, as shown in FIG. 5, the support layer 600 may be formed on the reflective layer 400. The support layer 600 may include any one of a metal, a metal alloy, a dielectric, a semiconductor, and a polymer.

In this case, a coupling metal layer 510 may be positioned between the reflective layer 400 and the support layer 600, and a diffusion barrier layer 500 may be further included between the coupling metal layer 510 and the reflective layer 400. have.

The formation of the support layer 600 described above may be formed by a method such as plating and bonding, and more specifically, electroplating, electroless plating, physical vapor deposition (PVD), and CVD (chemical) vapor deposition), and in this case, the coupling metal layer 510 may or may not be necessary.

On the other hand, it can be bonded by a semiconductor wafer bonding (wafer bonding), in this case a metal layer such as a bonding metal layer should be located between the support layer 600 and the reflective layer 400.

In this case, the diffusion barrier layer 500 may prevent the metal from invading the other layer during the formation or attachment of the support layer 600.

Next, a process of removing the substrate 100 is performed, and when the n-type electrode 700 is formed on the semiconductor layer 200 where the substrate 100 is removed as described above, as shown in FIG. 6, p- A vertical light emitting device having a structure in which the type semiconductor layer 230 and the n-type semiconductor layer 210 are reversed with each other is manufactured.

As illustrated, the bonding surface of the p-type electrode 300 and the reflective layer 400 may have a large coupling force due to the formation of a pattern or surface roughness, thereby forming a stable vertical light emitting device structure.

In this case, the surface roughness structure of the p-type electrode 300 may include a pattern having various shapes such as a long ridge shape, a lattice shape, a bump shape, and an optimum coupling force and reflection efficiency for each shape. Alternatively, the width and the depth between the unit structures of the pattern that may cause the light extraction efficiency may be determined.

In order to form the pattern of the surface of the p-type electrode 300, an etching mask is formed on the surface of the p-type electrode 300 using photoresist, followed by dry etching or wet etching. Wet etching may form a pattern or surface roughness structure of a desired shape.

In addition, after the formation of the pattern 310 structure, sputtering or chemical etching using an inert gas in a vacuum chamber to remove contaminants on the surface of the p-type electrode 300. chemical etching). In addition, a finer pattern 310 structure may be formed by sputtering using an inert gas without using photolithography when forming the pattern 310.

Meanwhile, the pattern may have a pattern 320 having a lens shape 321 as shown in FIGS. 7 and 8. That is, as shown in FIG. 7, when referring to the p-type electrode 300, as shown in FIG. 7, the pattern 320 may have a concave lens shape 321. As shown in FIG. 8, It may have a pattern 330 having a convex lens shape 331.

Third Embodiment

As shown in FIG. 9, two metal layers 500 and 510 are positioned on the support layer 600, and the metal layers 500 may be diffusion barrier layers 500 and bonding metal layers 510, respectively. That is, the bonding metal layer 510 may be easily bonded to the support layer 600, and the diffusion barrier layer 500 may be disposed on the pattern formed on the p-type electrode 300 to be connected to the p-type electrode 300. The embodiments to be combined are shown.

On the p-type electrode 300, the semiconductor layer 200 including the p-type semiconductor layer 230, the active layer 220, and the n-type semiconductor layer 210 is positioned, and the n-type semiconductor layer 210 is located. On the n-type electrode 700 is located.

Hereinafter, parts not described may be the same as in the second embodiment.

Fourth Embodiment

As shown in FIG. 10, the fourth embodiment shows an embodiment in which the support layer 600 is directly bonded to the pattern of the p-type electrode 300.

That is, the p-type electrode 300 is positioned on the support layer 600, and the pattern is positioned at the bonding surface between the support layer 600 and the p-type electrode 300.

On the p-type electrode 300, the semiconductor layer 200 including the p-type semiconductor layer 230, the active layer 220, and the n-type semiconductor layer 210 is positioned, and the n-type semiconductor layer 210 is located. On the n-type electrode 700 is located.

Hereinafter, parts not described may be the same as in the second embodiment.

Fifth Embodiment

As shown in FIG. 11, the reflective layer 400 may be directly formed on the support layer 600. That is, as in the second embodiment, the p-type electrode 300 is coupled to the reflective layer 400 through a pattern, and the support layer 600 is directly formed on the reflective layer 400.

That is, the bonding force with the reflective layer 400 may be increased by the surface roughness or the pattern formed on the p-type electrode 300.

In addition, the support layer 600 may be formed on the reflective layer 400 by a metal or a metal alloy, such as plating.

On the p-type electrode 300, the semiconductor layer 200 including the p-type semiconductor layer 230, the active layer 220, and the n-type semiconductor layer 210 is positioned, and the n-type semiconductor layer 210 is located. On the n-type electrode 700 is located.

Hereinafter, parts not described may be the same as in the second embodiment.

The above embodiment is an example for explaining the technical idea of the present invention in detail, and the present invention is not limited to the above embodiment, various modifications are possible, and various embodiments of the technical idea are all protected by the present invention. It belongs to the scope.

1 is a cross-sectional view showing a first embodiment of a vertical light emitting device.

2 to 8 are cross-sectional views showing a second embodiment of a vertical light emitting device,

2 to 6 are cross-sectional views showing each manufacturing step.

7 and 8 are cross-sectional views each showing an embodiment of a pattern on a p-type electrode.

9 is a sectional view showing a third embodiment of a vertical light emitting device.

10 is a sectional view showing a fourth embodiment of a vertical light emitting device.

11 is a cross-sectional view showing a fifth embodiment of the vertical light emitting device.

Claims (11)

In the vertical light emitting device, A semiconductor layer of a multilayer structure; A first electrode disposed on the semiconductor layer and having a surface roughness or a pattern formed on the other side of the semiconductor layer; And a metal layer disposed on the first electrode. The vertical light emitting device of claim 1, wherein the metal layer is a reflective layer positioned on the first electrode. The vertical type light emitting device of claim 2, further comprising a support layer on the reflective layer. The vertical light emitting device of claim 3, wherein the support layer comprises any one of a metal, a metal alloy, a dielectric, a semiconductor, and a polymer. The vertical type light emitting device of claim 1, wherein the metal layer is a support layer that supports a light emitting device structure. The vertical light emitting device according to claim 1, wherein the pattern is any one of a lattice pattern, an uneven pattern, and a plurality of lens shapes. 7. The vertical light emitting device according to claim 6, wherein the lens shape is convex or concave toward the metal layer. The vertical type light emitting device according to claim 1, wherein the pattern is a photonic crystal pattern. The vertical type light emitting device according to claim 1, wherein the first electrode is a transparent electrode layer. A support layer; A reflective layer on the support layer; A first electrode on the reflective layer; A semiconductor layer having a multilayer structure positioned on the first electrode; Comprising a second electrode located on the semiconductor layer, And a pattern is formed on the contact surface between the reflective layer and the first electrode. Forming a semiconductor layer of a multilayer structure on the substrate; Forming a first electrode on the semiconductor layer; Forming a pattern on the first electrode; Forming at least one metal layer on the first electrode on which the pattern is formed; Removing the substrate; And forming a second electrode on the exposed semiconductor layer by removing the substrate.

Images