KR101072099B1 - Light emitting diode and method for manufacturing led - Google Patents

Abstract

The present invention discloses a light emitting diode and a method of manufacturing the same, which improve the light efficiency by increasing the area of the active layer to be laminated by patterning a gallium nitride layer of the light emitting diode into an uneven structure. The disclosed invention comprises forming a buffer layer on a sapphire substrate; Forming a slow growth gallium nitride layer on the buffer layer; Forming a first gallium nitride layer on the slow growth gallium nitride layer; Applying a photoresist on the first gallium nitride layer, and then exposing and developing the photoresist to pattern the photoresist; Etching the first gallium nitride layer along the patterned photoresist; Forming a second gallium nitride layer on the first gallium nitride layer; Forming an active layer on the second gallium nitride layer; And forming a third gallium nitride layer on the active layer. Characterized in that it comprises a.

Light Emitting Diode, Unevenness, Active Layer, Etching, Light Efficiency

Description

LIGHT EMITTING DIODE AND METHOD FOR MANUFACTURING LED}

1 is a cross-sectional view showing the structure of a light emitting diode according to the prior art.

2A to 2H are cross-sectional views showing a light emitting diode manufacturing process according to the present invention.

3 is an enlarged cross-sectional view of an uneven region of a light emitting diode according to the present invention;

* Description of the symbols for the main parts of the drawings *

200: sapphire substrate 201: buffer layer

203: slow growth gallium nitride layer 205a: first GaN layer

205b: second GaN layer 207: active layer

209: P-GaN layer 300: photoresist (PR)

The present invention relates to a light emitting diode, and more particularly, to a light emitting diode and a method of manufacturing the light emitting diode having improved light efficiency by increasing the area of the active layer.

In general, a light emitting diode (LED) is a compound semiconductor that converts electricity into infrared or light to send and receive signals. It is a kind of semiconductor used for home appliances, remote controls, and electronic displays. Used for displays, indicators, and various automation devices.

The operating principle of the LED is that when a forward voltage is applied to a semiconductor of a specific element, electrons and holes move and recombine with each other through a junction portion of a positive and negative electrode, and an energy level is caused by the combination of electrons and holes. Fall and light is emitted.

In addition, the LED is generally 0.25 mm 2, which is very small and manufactured in size, and is mounted on an epoxy mold, a lead frame, and a PCB. Currently, the most commonly used LEDs are 5mm (T 1 3/4) plastic packages or new types of packages depending on the specific application. The color of the light emitted by the LED creates a wavelength depending on the composition of the semiconductor chip components, and the wavelength determines the color of the light.

In particular, LEDs are becoming smaller and smaller, such as resistors, capacitors, and noise filters, due to the trend toward miniaturization and slimming of information and communication devices, and directly mounting them on a PCB (Printed Circuit Board) board. In order to make the surface mount device (SMD) type.

Accordingly, LED lamps, which are used as display elements, are also being developed in SMD type. Such SMD can replace the existing simple lighting lamp, which is used for lighting indicators of various colors, character display and image display.

1 is a cross-sectional view showing the structure of a light emitting diode according to the prior art.                         

As shown in FIG. 1, a GaN buffer layer 101 made of gallium nitride (GaN) is formed on a sapphire substrate 100 made of Al ₂ O ₃ . Then, an undoped GaN layer 103 is formed on the buffer layer 101 by successive growth.

As described above, metal organic chemical vapor deposition (MOCVD) is generally used to grow a thin film of Group 3 series on the sapphire substrate 100, and the growth pressure is 200 torr (torr). Form a layer while maintaining 650 torr.

An N-type GaN layer 105 is formed on the undoped GaN layer 103, and silicon using silicon tetrahydride (Si: H 4) or silicon dihydrogen (Si 2 H 6) gas is used to form the N-type GaN layer 105.

When the N-type gallium nitride layer (GaN) 105 is grown, an active layer 109 is grown on the N-type gallium nitride layer 105. The active layer 109 is a semiconductor layer to which a light emitting material made of indium gallium nitride (InGaN) is added. As the active layer 109 grows, a P-type gallium nitride layer 110 is formed.

The P-type gallium nitride layer 110 is contrasted with the N-type gallium nitride layer 105. The N-type gallium nitride layer 105 moves electrons by a voltage applied to the outside, and the P-type gallium nitride layer 105 is relatively In the gallium nitride layer 110, holes are moved by a voltage applied to the outside, and holes and electrons in the active layer 109 combine with each other to emit light.

A transparent ITO metal layer (TM) is formed on the P-type gallium nitride layer 110 to transmit light generated from the active layer 109 to emit light to the outside.

After forming the transparent metal (TM) layer, a P-type electrode is formed to complete a light emitting diode.

Recently, a technology for improving the light efficiency of a light emitting diode has been developed. For example, the amount of light is increased by increasing the area of the active layer.

However, in the case of LEDs laminated on the sapphire substrate as in the prior art, there is a limit in increasing the area of the active layer.

In addition, in order to increase the area of the active layer, when the chip size is increased, there is a problem that the number of light emitting diodes manufactured per wafer is reduced and the production yield is lowered.

In order to increase the area of the active layer of the light emitting diode, the GaN layer formed under the active layer is etched in an uneven form, and the active layer is grown on the etched GaN layer to form an uneven active layer having an increased surface area. An object of the present invention is to provide a light emitting diode having improved light efficiency and a method of manufacturing the same.

A light emitting diode manufacturing method according to the present invention for achieving the above object,                     

Forming a buffer layer on the substrate;

Forming a slow growth gallium nitride layer on the buffer layer;

Forming a first gallium nitride layer on the slow growth gallium nitride layer;

Applying a photoresist on the first gallium nitride layer, and then exposing and developing the photoresist to pattern the photoresist;

Etching the first gallium nitride layer along the patterned photoresist;

Forming a second gallium nitride layer on the first gallium nitride layer;

Forming an active layer on the second gallium nitride layer; And

Forming a third gallium nitride layer on the active layer; Characterized in that it comprises a.

Herein, the first gallium nitride layer is etched into an uneven shape, the second gallium nitride layer is formed into an uneven shape, the active layer is formed into an uneven shape, and the third gallium nitride layer is formed into an uneven shape. It features.

The first gallium nitride layer is formed to a thickness of 1 ~ 3㎛, the second gallium nitride layer is characterized in that formed to a thickness of 1 ~ 2㎛.

The light emitting diode according to the present invention,

Board;

A buffer layer and a low growth gallium nitride layer sequentially stacked on the substrate;

Uneven first and second gallium nitride layers formed on the low-growth gallium nitride layer;                     

An uneven type active layer laminated on the second gallium nitride layer having the uneven structure; And

And an uneven third gallium nitride layer formed on the uneven active layer.

According to the present invention, in order to increase the area of the active layer of the light emitting diode, a GaN layer formed under the active layer is etched in an uneven form, and an active layer is grown on the etched GaN layer to form an uneven active layer having an increased surface area. To improve the light efficiency.

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

2A to 2H are cross-sectional views showing a light emitting diode manufacturing process according to the present invention.

2A to 2C, a buffer layer having an In (x) Ga (1-x) N composition on a sapphire (Al ₂ O ₃ ) substrate 200 under a constant temperature condition (about 500 to 600 ° C.) (GaN buffer layer: 201) is formed, and a low-growth gallium nitride layer 203 is continuously formed on the buffer layer 201.

The slow growth gallium nitride layer 203 is formed of an undoped GaN component in which defects of the buffer layer 201 are to be formed after the slow growth gallium nitride layer 203, and defects in adjacent nitride layers Form to prevent it from propagating.                     

When the slow growth gallium nitride layer 203 is formed, a GaN layer 205 to which impurity (N) is added is subsequently formed. The GaN layer 205 grows to have a thickness of about 1 μm to 3 μm.

When the GaN layer 205 is formed, as shown in FIG. 2D, a photosensitive material such as a photo resist 300 is coated, and the pattern is formed into an uneven shape by exposing and etching the same.

When the photoresist 300 is patterned, the GaN layer 205 formed thereon is etched using the photoresist 300 as a mask, and as shown in FIG. 2E, the surface of the GaN layer 205 has a first GaN layer having an uneven structure. 205a is formed.

The structure of the first GaN layer 205a is etched into an uneven shape, but when etched, the low-growth gallium nitride layer 203 grown below is not opened.

That is, the surface of the first GaN layer 205a has an uneven structure, but the surface of the lower slow growth gallium nitride layer 203 is not exposed in the recessed groove region.

Then, as shown in FIG. 2F, a second GaN layer 205b is continuously formed on the first GaN layer 205a, wherein the thickness of the second GaN layer 205b is the second GaN. Growth is formed to a thickness of 1 to 2 占 퐉 slightly thinner than the thickness of the layer 205a.

When the second GaN layer 205b is grown on the first GaN layer 205a, it is grown along the surface structure of the first GaN layer 205a, so that the surface of the second GaN layer 205b is also grown. It has an uneven shape.

By growing the second GaN layer 205b without directly forming an active layer 207 on the first GaN layer 205a, defects due to surface irregularities of the first GaN layer 205a are caused. Are not transferred to the active layer 207.

Therefore, the reliability of the device can be secured while increasing the light efficiency by increasing the area of the active layer 207.

When the second GaN layer 205b is grown as described above, as shown in FIG. 2G, the active layer 207 is grown and formed. Since the active layer 207 grows along the surface concave-convex structure of the second GaN layer 205b, the surface is grown into a layer having a concave-convex structure, thereby increasing the surface area as a whole.

When the active layer 207 is formed, as shown in FIG. 2H, the P-GaN layer 209 doped with impurities of the Mg component is grown to complete the light emitting diode.

At this time, since the surface structure of the P-GaN layer 209 is formed along the active layer 207 having the uneven structure, it has an uneven structure.

3 is an enlarged cross-sectional view of an uneven region of a light emitting diode according to the present invention.

As shown in FIG. 3, the buffer layer 201 is grown on the sapphire substrate 200, and the slow-growing gallium nitride layer 203 is grown on the buffer layer 201.

A first GaN layer 205a is formed in an uneven structure on the gallium nitride layer 203, and a second GaN layer 205b is formed on the first GaN layer 205a.

Since the surface structure of the first GaN layer 205a is a concave-convex structure, all the layers to be laminated later are formed in a concave-convex structure.                     

Accordingly, the surface of the second GaN layer 205b has a concave-convex structure, and both the active layer 207 and the P-GaN layer 209 formed on the second GaN layer 205b have a concave-convex structure.

Therefore, the amount of light generated by increasing the area of the active layer 207 increases.

Since the structure of the P-GaN layer 209 formed on the active layer 207 also has an uneven structure, more light can be generated to the outside.

Therefore, in the present invention, by forming the GaN layer formed under the active layer in the concave-convex structure, the active layer and the P-GaN layer formed after the concave-convex structure have the advantage of improving the light efficiency.

In addition, since the size of the sapphire substrate corresponding to one chip size is maintained in the same size as in the prior art, the number of light emitting diodes produced in one wafer is the same, so that the output is not reduced.

As described in detail above, in order to increase the active layer area of the light emitting diode, the present invention etches the GaN layer formed under the active layer in an uneven form, and grows the active layer on the etched GaN layer, thereby increasing the surface area. There is an effect of improving the light efficiency by forming an uneven active layer.

In addition, in the present invention, by forming a GaN layer as a double layer under the active layer having a concave-convex structure, there is an advantage of preventing device defects from being transferred to the active layer and improving device reliability.                     

The present invention is not limited to the above-described embodiments, and various changes can be made by those skilled in the art without departing from the gist of the present invention as claimed in the following claims.

Claims (11)

Forming a buffer layer on the substrate; Forming a slow growth gallium nitride layer on the buffer layer; Forming a first gallium nitride layer on the slow growth gallium nitride layer; Applying a photoresist on the first gallium nitride layer, and then exposing and developing the photoresist to pattern the photoresist; Etching the first gallium nitride layer along the patterned photoresist; Forming a second gallium nitride layer on the first gallium nitride layer; Forming an active layer on the second gallium nitride layer; And Forming a third gallium nitride layer on the active layer; Light emitting diode manufacturing method comprising a. The method of claim 1, The first gallium nitride layer is etched in a concave-convex shape, characterized in that the light emitting diode manufacturing method. The method of claim 1, The second gallium nitride layer is a light emitting diode manufacturing method, characterized in that formed in the concave-convex shape. The method of claim 1, The active layer is a light emitting diode manufacturing method, characterized in that formed in the concave-convex shape. The method of claim 1, The third gallium nitride layer is a light emitting diode manufacturing method, characterized in that formed in the concave-convex shape. The method of claim 1, The first gallium nitride layer is a light emitting diode manufacturing method, characterized in that formed in a thickness of 1 ~ 3㎛. The method of claim 1, The second gallium nitride layer is a light emitting diode manufacturing method, characterized in that formed in a thickness of 1 ~ 2㎛. Board; A buffer layer and an undoped gallium nitride layer sequentially stacked on the substrate; An uneven first n-type gallium nitride layer formed on the undoped gallium nitride layer; An uneven second n-type gallium nitride layer formed on the first n-type gallium nitride layer and having a thickness thinner than that of the first n-type gallium nitride layer; An uneven type active layer formed on the second gallium nitride layer having the uneven structure; And And an uneven p-type gallium nitride layer formed on the uneven active layer. The method of claim 8, The thickness of the first gallium nitride layer is 1 to 3㎛ light emitting diode, characterized in that. The method of claim 8, The thickness of the second gallium nitride layer is 1 to 2㎛ light emitting diode. The method of claim 8, A light emitting diode, characterized in that the amount of light emission is increased by increasing the surface area of the uneven type active layer.

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