KR100691111B1 - Light emitting diode of vertical electrode type and fabricating method thereof - Google Patents

Abstract

The present invention relates to a vertical light emitting diode and a method of manufacturing the same, which are formed spaced apart from each other on a substrate, and forming a separation post between a plurality of light emitting structures having a variety of designs without the scribing process The structures are separated into light emitting diodes having various designs.

According to the present invention, the structure of the light emitting diode can be removed from the uniform rectangular structure to have a structure necessary for the actual use of the light emitting diode, and the structure of the light emitting diode can be manufactured to be close to a circular shape to improve thermal, electrical, and optical characteristics of the device. It can be effective.

Vertical Light Emitting Diodes, Scribing, Blue Tape

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.

Figure 2a to 2g is a cross-sectional view showing an embodiment of a vertical light emitting diode manufacturing method of the present invention.

3 illustrates embodiments of various forms of light emitting structures formed on a substrate.

4 is a view showing a case in which a collision occurs during separation of the light emitting structure.

5 is a view illustrating a separation post formed in an area between a plurality of light emitting structures having various shapes;

6 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: UBM (Under Bump Metallization) layer 150: separation post

160: conductive support film 170: n-electrode

180: blue tape

The present invention relates to a vertical light emitting diode and a method of manufacturing the same, and more particularly to a vertical light emitting diode having a variety of designs and a method of manufacturing the same.

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, at least a portion 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 and the luminous efficiency according to the device size versus luminance. There is a problem of this deterioration.

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 around the light emitting structure 11 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, when copper (Cu) is used as the conductive support film, the copper (Cu) is easily deformed, so in the scribing process by a diamond tip or the like. There is a problem in that cracking is not formed and plastic deformation occurs, so that the subsequent braking process is not easy.

In addition, since the light emitting diode is separated by the scribing and breaking process, the shape of the light emitting diode is almost uniformly deviated from the rectangular structure, and thus, there is a problem in that the shape of the light emitting diode for each application cannot be designed.

That is, in manufacturing a conventional vertical light emitting diode, since the scribing process has to be performed, the light emitting diode has not been manufactured in various forms, but has been manufactured only in a rectangular structure. In this case, the light emitting diode has been subjected to electrical, optical, and thermal characteristics. There is a problem that can not but have a limit.

Therefore, an object of the present invention is formed on a substrate spaced apart from each other, by forming a separation post between a plurality of light emitting structures having various designs to separate the plurality of light emitting structures without a scribing process to separate LEDs The present invention provides a vertical light emitting diode having various designs and a method of manufacturing the same.

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 a substrate and having a predetermined shape, 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 an under bump metallization (UBM) layer surrounding the top of the substrate and the insulating film, Forming a separation post between the plurality of light emitting structures on the UBM layer, forming a conductive support film surrounding the UBM layer and the separation post, and laser lift off (LLO) process Separating the substrate from the plurality of light emitting structures, and forming an n-electrode below the plurality of light emitting structures. After that, the step of removing the separation post, and separating the plurality of light emitting structure to form a separate light emitting diode characterized in that it comprises a.

Here, the shape of the light emitting structure is characterized in that it has a structure that does not pass the outer surface of the neighboring light emitting structure when a line drawn from the center of the light emitting structure to the outer surface of the light emitting structure.

An embodiment of the vertical light emitting diode of the present invention is formed by sequentially stacking an active layer and a p-type nitride semiconductor layer on an n-type nitride semiconductor layer, a light emitting structure having a predetermined shape, and p- formed on the light emitting structure An electrode, an n-electrode formed under the light emitting structure, a sidewall of the light emitting structure, an insulating film formed on an upper portion of the light emitting structure in which the p-electrode is not formed, and surrounding the insulating film; An under bump metallization (UBM) layer formed on the substrate, and a conductive support film formed to surround the UBM layer.

Here, the shape of the light emitting structure is characterized in that any one of a triangle, a square, a rhombus, a cross, a hexagon.

Hereinafter, a method of manufacturing a vertical light emitting diode of the present invention will be described in detail with reference to FIGS. 2 to 6. 2A to 2G are cross-sectional views showing an embodiment of a method of manufacturing a vertical light emitting diode of the present invention.

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

In addition, the plurality of light emitting structure 110 has a predetermined shape, in order to form repeatedly on the substrate 100, the outer surface to have three, four, six, etc., in particular close to the circular It is preferable to form so that it may have six surfaces which are structures.

The p-electrode 120 is formed on the plurality of light emitting structures 110.

Subsequently, after the 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, the sapphire substrate 100 is formed. Surrounding the upper portion of the and the plurality of light emitting structure 110 to form an UBM (Under Bump Metallization) layer 140 (FIG. 2b).

In this case, the insulating layer 130 is a passivation layer and 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.

In addition, the UBM layer 140 serves as a seed layer in forming the conductive support layer. The UBM layer 140 is made of any one material selected from Cr, Au, Ti, and Cu.

Subsequently, a separation post 150 is formed in an area between the plurality of spaced apart light emitting structures 110 (FIG. 2C). The separation post 150 is preferably made of photoresist or polyimide.

Next, the conductive support layer 160 is formed to surround the UBM layer 140 and the separation post 150 (FIG. 2D). 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.

When the conductive support layer 160 is formed, an interface region 165 that is not completely bonded from the separation post 150 to the surface of the conductive support layer 160 on the separation post 150. Is generated.

Thereafter, a laser lift off (LLO) process is performed to separate the substrate 100 from the plurality of light emitting structures 110 (FIG. 2E).

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.

Subsequently, after forming the n-electrode 170 under the plurality of light emitting structures 110, the separation post 150 is removed using an organic solvent such as acetone (FIG. 2F).

Next, a blue tape 180 is attached to the conductive support layer 160 and then an expanding process is performed to separate the plurality of light emitting structures 110 into separate light emitting diodes ( 2g).

In this case, the plurality of light emitting structures are formed on the upper part of the separation post 150 because the boundary area 165 is not completely bonded from the separation post 150 to the surface of the conductive support layer 160. The 110 are easily separated.

In addition, since it is easy to break the bonding state of the UBM layer 140 formed under the separation post 150, the separation of the plurality of light emitting structures 110 is not a major obstacle.

As such, when the separating posts 150 are formed in regions between the light emitting structures 110 spaced apart from each other, the plurality of light emitting structures 110 may be separated into separate light emitting diodes without a scribing process. .

Accordingly, after the shapes of the plurality of light emitting structures 110 are manufactured in various shapes as necessary, the light emitting diodes having various shapes may be manufactured by separating them as shown in FIG. 2G.

3 is a diagram illustrating embodiments of various forms of a light emitting structure formed on a substrate. As shown therein, the light emitting structure has a shape of a triangle, a square, a rhombus, a cross, a hexagon, and the like.

In this case, the light emitting structure should have a form for being repeatedly formed on the substrate, and in order to separate them, it should be such that there is no collision with each other. 4 is a diagram illustrating a case where a collision occurs when the light emitting structure is separated.

As such, in order to prevent the light emitting structure from colliding with the adjacent light emitting structure when the light emitting structure is separated, a line drawn from the center of the light emitting structure to the outer surface of the light emitting structure does not pass the outer surface of the adjacent light emitting structure.

In addition, the light emitting structure is formed so that its outer surface has a circular structure, for example, a hexagon in FIG. 3, and has excellent characteristics in electrical, optical, and thermal reliability.

That is, when the light emitting structure has a structure close to a circle, the distances from the center of the light emitting structure to the outer surface are all the same, so that the resistance from the center of the light emitting structure to the outer surface is the same. The same current flows through the active layer to uniformly emit light throughout the active layer, and the heat distribution is also constant, thereby improving the electrical, optical, and thermal reliability of the light emitting device.

However, the light emitting structure may be formed to have various types of designs according to actual application examples of the light emitting device even though a slight loss in electrical, optical and thermal reliability.

5 is a view illustrating a separation post formed in an area between a plurality of light emitting structures having various shapes. As shown therein, the separating posts are continuously formed along a region between the plurality of light emitting structures spaced apart from each other.

6 is a cross-sectional view showing an embodiment of a vertical light emitting diode of the present invention. As shown in FIG. 2, 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 predetermined shape, and on the light-emitting structure. The p-electrode 240 is formed, the n-electrode 250 formed under the light emitting structure 200, and the sidewalls of the light emitting structure 200 are enclosed, and the p-electrode 240 is not formed. An insulation layer 260 formed on the light emitting structure 200, an insulation layer 260, and an UBM layer 270 formed on the p-electrode 240, and the UBM layer 270. And a conductive support film 280.

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 and mainly 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.

As illustrated in FIG. 3, the light emitting structure 200 may have a triangular shape, a square shape, a rhombus shape, a cross shape, a hexagon shape, or the like. In particular, the light emitting structure 200 has an excellent structure in terms of electrical, optical, and thermal reliability, as the outer surface thereof has a circular structure, for example, a hexagonal shape in FIG. 3.

The light emitting structure 200 may be formed to have various types of designs according to the actual application examples of the light emitting device as well as the shape shown in FIG. 3.

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 on the sidewall of the light emitting structure 200 to form a region other than the p-electrode 240 formed on the p-type nitride semiconductor layer 230. Is made of any one selected from SiO ₂ , Si ₃ N ₄ , Al ₂ O ₃ , TiO ₂ .

An under bump metallization (UBM) layer 270 is formed on the p-electrode 240 to surround the insulating layer 260. 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, light emitting diodes having various designs are formed by being spaced apart from each other on a substrate and separating the plurality of light emitting structures without a scribing process by forming a separating post between a plurality of light emitting structures having various designs. There is an effect that can be prepared.

In addition, the structure of the light emitting diode can be removed from the rectangular structure to have a structure necessary for the actual use of the light emitting diode, and the light emitting diode can be manufactured in a structure close to a circle to improve the thermal, electrical and optical characteristics of the device. It works.

Claims (12)

Forming a plurality of light emitting structures spaced apart from each other on the substrate and having a predetermined shape, 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 an under bump metallization (UBM) layer around the substrate and the insulating layer; Forming a separating post between the plurality of light emitting structures on the UBM layer; Forming a conductive support film surrounding the UBM layer and the separation post; Separating the substrate from the plurality of light emitting structures in a laser lift off (LLO) process; Forming an n-electrode below the plurality of light emitting structures, and then removing the separating posts; And Attaching a blue tape to the upper portion of the plurality of light emitting structures, and separating the plurality of light emitting structures by an expanding process to form a separate light emitting diode. Manufacturing method. The vertical light emitting diode of claim 1, wherein the light emitting structure has a structure that does not pass the outer surface of a neighboring light emitting structure when a line is drawn from the center of the light emitting structure to the outer surface of the light emitting structure. Manufacturing method. The method of claim 1, wherein the light emitting structure has any one of a triangle, a square, a rhombus, a cross, and a hexagon. 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 an n-type nitride semiconductor layer, an active layer, and a p-type nitride semiconductor layer are sequentially formed. The method of claim 1, wherein the separation post is made of photoresist or polyimide. delete an active layer and a p-type nitride semiconductor layer are sequentially stacked on the n-type nitride semiconductor layer and have a hexagonal shape; A p-electrode formed on the light emitting structure; An n-electrode formed below the light emitting structure; An insulating layer surrounding a sidewall of the light emitting structure and formed on the light emitting structure in which the p-electrode is not formed; An under bump metallization (UBM) layer surrounding the insulating layer and formed on the p-electrode; And Vertical light emitting diode comprising a conductive support film formed surrounding the UBM layer. delete The method of claim 8, wherein the insulating film is SiO ₂ , Si ₃ N ₄ , Al ₂ O ₃ , TiO ₂ Vertical light emitting diode, characterized in that made of any one. The vertical light emitting diode of claim 8, wherein the UBM layer is made of any one of Cr, Au, Ti, and Cu. The vertical type light emitting diode of claim 8, wherein the conductive support film is made of Cu or Au.

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