KR100617873B1 - Light emitting diode of vertical electrode type and fabricating method thereof - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical light emitting diode and a method of manufacturing the same, wherein a SOG (Spin On Glass) having hardness is formed in a region between light emitting structures spaced apart from each other on a substrate, and then a conductive support layer is formed on the SOG. And forming a separate light emitting diode by scribing the SOG-formed portion.

According to the present invention, by forming a SOG (Spin On Glass) surrounding the light emitting structures spaced apart from each other on the substrate, by forming a conductive support layer on the SOG, the thermal and electrical conductivity of the conductive support layer is maintained as it is. In the process after the laser lift-off process, the handle is not easily bent at the time of handling, and thus the process of polishing and electrode formation can be easily performed.

In addition, by scribing a portion on which the SOG (Spin On Glass) is formed, a crack is formed during scribing to separate the plurality of light emitting structures into separate light emitting diodes without plastic deformation.

Laser Lift Off, Conductive Support Film, SOG, UBM

Description

Light emitting diode of vertical electrode type and fabricating method

1A to 1F are cross-sectional views illustrating a method of manufacturing a conventional vertical light emitting diode.

2A to 2H are sectional views showing an embodiment of a method of manufacturing a vertical light emitting diode of the present invention.

3 is a cross-sectional view showing an embodiment of a vertical light emitting diode of the present invention.

Explanation of symbols on the main parts of the drawings

100 substrate 110 light emitting structure

120 p-electrode 130 insulating film

140: SOG 150: UBM

160: conductive support film 170: n-electrode

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical light emitting diode and a method of manufacturing the same, wherein a laser on-off is formed by forming spin on glass (SOG) having a predetermined hardness in a region between a plurality of mutually spaced light emitting structures before forming a conductive support layer. It relates to a vertical light emitting diode and a method of manufacturing the same that facilitates the process after the step.

In general, a light emitting diode (LED) is a kind of semiconductor device that transmits and receives a signal by converting electricity into infrared rays or light using characteristics of a compound semiconductor.

The light emitting diode generates energy with high efficiency at low voltage, so it is very energy-saving.In recent years, the luminance problem, which was the limitation of the light emitting diode, has been greatly improved, and the entire industry including a backlight unit, an electronic board, an indicator, a home appliance, and various automation devices It is used throughout.

Particularly, gallium nitride (GaN) -based light emitting diodes have a broad emission spectrum ranging from ultraviolet rays to infrared rays and are environmentally friendly since they do not contain environmentally harmful substances such as arsenic (As) and mercury (Hg). I get a high response.

In the conventional GaN-based light emitting diode, since sapphire (Al ₂ O ₃ ), which is an insulating material, is used as a substrate, two electrodes, that is, a p-electrode and an n-electrode, have to be formed in a substantially horizontal direction. The current flow from the n-electrode through the active layer to the p-electrode must be narrowly formed along the horizontal direction. Due to this narrow current flow, the light emitting diode has an increased forward voltage and thus lowers current efficiency.

In the conventional GaN-based light emitting diode, in order to form the n-electrode, the partial area of the active layer must be removed at least wider than the area of the n-electrode, so that the light emitting area is reduced to emit light according to the device size / luminance There is a problem that the efficiency is lowered.

In addition, the conventional GaN-based light emitting diode has a large amount of heat generated by an increase in current density, whereas the sapphire substrate has a low thermal conductivity, and thus heat emission cannot be performed smoothly. There is a problem that the device is unstable due to the occurrence of mechanical stress in the liver.

In order to solve this problem, a vertical GaN-based light emitting diode having a sapphire substrate removed through a laser lift off (LLO) process has recently been developed, and the vertical GaN-based light emitting diode is a conventional GaN-based light emitting diode. Unlike, the shape of the electrode is formed on the lower surface and the upper surface of the light emitting structure.

1A to 1F are cross-sectional views illustrating a method of manufacturing a conventional vertical light emitting diode. As shown therein, a plurality of light emitting structures 11 are formed on the sapphire substrate 10 and spaced apart from each other, and a p-electrode 12 is formed on the plurality of light emitting structures 11 (FIG. 1A). .

Subsequently, an insulating layer 13 is formed on sidewalls of the plurality of light emitting structures 11 and the plurality of light emitting structures 11 on which the p-electrodes 12 are not formed, and the sapphire substrate 10 is formed. An under bump metallization (UBM) film 14 is formed on the upper part and the light emitting structure 11 (FIG. 1B).

Next, the conductive support layer 15 is formed to surround the under bump metallization (UBM) layer 14 (FIG. 1C). Thereafter, the sapphire substrate 10 is separated from the light emitting structure 11 using a laser lift off process (FIG. 1D).

Subsequently, an n-electrode 16 is formed below the light emitting structure 11 (FIG. 1E), and then a scribing and breaking process is performed to separate the light emitting diodes 17 and 18. ) Is formed (FIG. 1F).

In the conventional vertical light emitting diode manufacturing method, an internal stress is generated in the process of forming the conductive support layer 15, and when the sapphire substrate 10 is removed by a laser lift-off process, the internal stress is a light emitting diode. There is a problem that the transition to the crack (crack) occurs.

In addition, since the conductive support layer 15 is as thin as several tens of micrometers, the surface of the light emitting structure 11 roughened by the laser lift-off process after removing the sapphire substrate 10 and the n-electrode ( In the process of forming 16, the conductive support film 15 may be bent like paper during handling, which may make it difficult to proceed with the processes.

In order to solve such a problem, a method of forming a thick conductive support layer has been proposed, but in this case, it is difficult to separate the light emitting diode into separate light emitting diodes in the scribing and breaking process.

In particular, when copper (Cu) is used as the conductive support film, since the copper (Cu) easily deforms, cracks are not formed in the scribing process by a diamond tip or the like, and plastic deformation is performed. There is a problem that the subsequent braking process is not easy to cause.

In the manufacturing method of the vertical light emitting diode, the scribing process and the braking process are different from the scribing process and the braking process when fabricating a general light emitting diode. The ice process is for sapphire with high hardness without any malleability and ductility, but the scribing process for manufacturing vertical light emitting diodes is performed because it is for a conductive support film including malleability and ductility.

In addition, the sapphire can be easily separated into the brittle fracture mode of the notched ceramic material even when the braking process is performed after the scribing process, while the conductive support film has a process problem that is not easily separated. .

Accordingly, an object of the present invention is to form a conductive support film to surround the light emitting structure and to form a SOG (Spin On Glass) having a certain hardness, so that the process after the laser lift-off process is not easily bent during handling by forming a conductive support film The present invention provides a vertical light emitting diode and a method for manufacturing the same, which are easily separated into separate light emitting diodes by scribing the SOG-formed portion.

Embodiments of the vertical light emitting diode of the present invention, a light emitting structure formed by sequentially stacking an active layer, a p-type nitride semiconductor layer on the n-type nitride semiconductor layer, a p-electrode formed on the light emitting structure, and the light emitting structure An n-electrode formed at a lower portion, an insulating film formed on a sidewall of the light emitting structure and an upper portion of the light emitting structure in which the p-electrode is not formed, a spin on glass (SOG) formed around the insulating film, and the SOG; An under bump metallization (UBM) layer formed on the p-electrode, and a conductive support layer formed to surround the UBM layer.

An embodiment of the manufacturing method of the vertical light emitting diode of the present invention, forming a plurality of light emitting structures spaced apart from each other on the substrate, and forming a p-electrode on the plurality of light emitting structures, and the plurality of light emitting structures Forming an insulating film on a sidewall of the substrate and an upper portion of the light emitting structure in which the p-electrode is not formed, forming a spin on glass (SOG) around the substrate and the insulating film, surrounding the SOG, Forming an under bump metallization (UBM) layer on the p-electrode, forming a conductive support layer surrounding the UBM layer, and separating the substrate from the plurality of light emitting structures by a laser lift-off process And forming an n-electrode under the plurality of light emitting structures, and separating the plurality of light emitting structures to form a separate light emitting diode. Characterized in that it comprises a step.

Hereinafter, a vertical light emitting diode of the present invention and a manufacturing method thereof will be described in detail with reference to FIGS. 2 to 3. 2A to 2H are cross-sectional views showing an embodiment of a method of manufacturing a vertical light emitting diode of the present invention.

As shown in FIG. 1, first, a plurality of light emitting structures 110 spaced apart from each other are formed on the substrate 100, and a p-electrode 120 is formed on the light emitting structure 110 (FIG. 2A).

Here, the substrate 100 is made of any one selected from sapphire (Al ₂ O ₃ ), silicon carbide (SiC), gallium arsenide (GaAs), the substrate in terms of being able to receive a high quality substrate at a low price It is preferable to use a sapphire substrate as (100).

A plurality of light emitting structures 110 are formed on the substrate 100 and spaced apart from each other. The plurality of light emitting structures 110 are formed by sequentially stacking an n-type nitride semiconductor layer, an active layer, and a p-type nitride semiconductor layer. do.

In addition, a buffer layer may be further formed between the substrate 100 and the n-type nitride semiconductor layer to overcome a difference in lattice mismatch and thermal expansion coefficient between the substrate 100 and the light emitting structure 110. The p-electrode 120 is formed on the plurality of light emitting structures 110.

Next, an insulating layer 130 is formed on the sidewalls of the plurality of light emitting structures 110 and the plurality of light emitting structures 110 on which the p-electrodes 120 are not formed (FIG. 2B).

The insulating layer 130 is a passivation layer, which electrically protects the light emitting structure 110. As the insulating layer 130, any one of SiO ₂ , Si ₃ N ₄ , Al ₂ O ₃ , and TiO ₂ may be selected and used.

Next, after forming the SOG (Spin On Glass) 140 surrounding the upper portion of the substrate 100 and the light emitting structure 110, the SOG formed on the p-electrode 120 is removed to remove the p- The electrode 120 is exposed from above (FIG. 2C).

Here, the SOG 140 is formed by spin coating a material such as glass (SiO ₂ ) in a liquid state and heat-treating at 400 to 500 ° C., and the SOG thus formed has a certain hardness.

Thereafter, an under bump metallization (UBM) layer 150 is formed on the p-electrode 120 to surround the SOG 140 (FIG. 2D). The UBM layer 150 serves as a seed layer in forming a conductive support layer. The UBM layer 150 is made of any one material selected from Cr, Au, Ti, and Cu.

Subsequently, the conductive support layer 160 is formed to surround the UBM layer 150 (FIG. 2E). The conductive support layer 160 is made of a conductive material, and particularly, a material having good thermal conductivity such as copper (Cu) or gold (Au) is mainly used.

Next, a laser lift off process is performed to separate the substrate 100 from the plurality of light emitting structures 110 (FIG. 2F). That is, when focusing and irradiating excimer laser light having a predetermined wavelength on the substrate 100, the substrate 100 and an interface between an n-type nitride semiconductor layer (not shown) of the light emitting structures 110 are provided. Thermal energy is concentrated so that the interface of the n-type nitride semiconductor layer (not shown) is separated into gallium and nitrogen molecules, and the substrate 100 is instantaneously separated at the portion where the laser light passes.

After the laser lift-off process, the roughened surface of the n-type nitride semiconductor layer (not shown) may be polished by an ICP / RIE (Inductively Coupled Plasma / Reactive Ion Etching) method.

Thereafter, an n-electrode 170 is formed under the plurality of light emitting structures 110 (FIG. 2G). Subsequently, after scribing a portion in which the SOG 140 is formed between the plurality of light emitting structures 110 by using a diamond tip or the like, a separate vertical type light emitting diode 180 or 190 is performed by performing a braking process. To form (FIG. 2H).

As such, when the SOG 140 having a predetermined hardness is formed before the conductive support layer 160 is formed, the SOG 140 is not bent or deformed during handling, and thus a post-process after removing the substrate 100 by the laser lift-off process is performed. If the scribing process is easy and the scribing process is performed on the SOG 140 during the scribing process, the braking process for forming cracks without plastic deformation and separating the individual light emitting diodes may be facilitated.

3 is a cross-sectional view showing an embodiment of a vertical light emitting diode of the present invention. As shown here, the active layer 220 and the p-type nitride semiconductor layer 230 are sequentially formed on the n-type nitride semiconductor layer 210 to form a light emitting structure 200, wherein the n-type nitride semiconductor layer Reference numeral 210 is made of a GaN compound semiconductor such as an n-type GaN layer, an n-type AlGaN layer, an n-type InGaN layer, or the like.

An active layer 220 is formed on the n-type nitride semiconductor layer 210, and the active layer 220 has a multi quantum wells (MQW) structure. In _x Ga _1-x N (0 <X ≤ 1).

A p-type nitride semiconductor layer 230 is formed on the active layer 220, and the p-type nitride semiconductor layer 230 corresponds to the n-type nitride semiconductor layer 210 and has a p-type GaN layer and a p-type AlGaN. And a GaN compound semiconductor such as a p-type InGaN layer.

A p-electrode 240 is formed on the p-type nitride semiconductor layer 230, and an n-electrode 250 is formed below the n-type nitride semiconductor layer 210.

The insulating layer 260 is formed in a region other than the p-electrode 240 formed on the p-type nitride semiconductor layer 230 to surround sidewalls of the light emitting structure 200. The insulating layer 260 is made of any one selected from SiO ₂ , Si ₃ N ₄ , Al ₂ O ₃ , TiO ₂ .

A spin on glass (SOG) 270 is formed to surround the insulating layer 260, and an under bump metallization (UBM) layer 280 is formed on the p-electrode 240 to surround the SOG 270. It is. Here, the UBM layer 280 is made of any one material selected from Cr, Au, Ti, Cu.

A conductive support layer 290 is formed on the UBM layer 280 with a predetermined thickness, and copper (Cu) or gold (Au) having good thermal conductivity is mainly used as the conductive support layer 290.

On the other hand, while the present invention has been shown and described with respect to specific preferred embodiments, various modifications and variations of the present invention without departing from the spirit or field of the invention provided by the claims below It will be readily apparent to one of ordinary skill in the art that it can be used.

According to the present invention, after forming a SOG (Spin On Glass) having a hardness in the area between the plurality of light emitting structures spaced apart from each other, by forming a conductive support film, the thermal and electrical conductivity of the conductive support film is maintained as it is, In the process after the laser lift-off process, it is not easily bent during handling, and thus the process of polishing and electrode formation can be easily performed.

In addition, by scribing a portion on which the SOG (Spin On Glass) is formed, a crack is formed during scribing to separate the plurality of light emitting structures into separate light emitting diodes without plastic deformation.

Therefore, due to plastic deformation, cracks inside the light emitting diode, which are generated when the plurality of light emitting structures are separated into separate light emitting diodes, do not occur, and thus, the yield may be improved.

Claims (8)

Forming a plurality of light emitting structures spaced apart from each other on the substrate, and forming a p-electrode on the plurality of light emitting structures; Forming an insulating film on sidewalls of the plurality of light emitting structures and on the light emitting structure in which the p-electrode is not formed; Forming a spin on glass (SOG) covering an upper portion of the substrate and the insulating layer; Surrounding the SOG and forming an under bump metallization (UBM) layer on the p-electrode; Forming a conductive support film surrounding the UBM layer; Separating the substrate from the plurality of light emitting structures in a laser lift off process; Forming an n-electrode below the plurality of light emitting structures; And And separating the plurality of light emitting structures to form a separate light emitting diode. The method of claim 1, wherein the substrate is made of sapphire (Al ₂ O ₃ ). The method of claim 1, wherein the light emitting structure is a structure in which a buffer layer, an n-type nitride semiconductor layer, an active layer, and a p-type nitride semiconductor layer are sequentially formed. 2. The vertical light emitting diode of claim 1, further comprising polishing a surface of the plurality of roughened light emitting structures during the laser lift-off process after separating the substrate from the plurality of light emitting structures. Manufacturing method. a light emitting structure in which an active layer and a p-type nitride semiconductor layer are sequentially stacked on the n-type nitride semiconductor layer; A p-electrode formed on the light emitting structure; An n-electrode formed below the light emitting structure; An insulating layer formed on the sidewalls of the light emitting structure and the light emitting structure in which the p-electrode is not formed; A spin on glass (SOG) formed surrounding the insulating layer; An under bump metallization (UBM) layer surrounding the SOG and formed on the p-electrode; And Vertical light emitting diode comprising a conductive support film formed surrounding the UBM layer. 6. The light emitting diode of claim 5, wherein the conductive support film is made of Cu or Au. The vertical type light emitting diode of claim 5, wherein the insulating layer is formed of any one selected from SiO ₂ , Si ₃ N ₄ , Al ₂ O ₃ , and TiO ₂ . The vertical light emitting diode of claim 5, wherein the UBM layer is made of any one material selected from Cr, Au, Ti, and Cu.

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