KR100674708B1 - Vertically structured gan type light emitting diode device and method of manufacturing the same - Google Patents

Abstract

A vertical GaN based light emitting diode and a manufacturing method thereof are provided to intensify ESD(ElectroStatic Discharge) characteristics without the degradation of brightness by using a PN junction structural substrate instead of a structure support layer. A vertical GaN based light emitting diode includes a PN junction structural substrate(470), a P type electrode(450) on the substrate, a P type GaN layer(440) on the P type electrode, an active layer(430) on the P type GaN layer, an N type GaN layer(420) on the active layer and an N type contact(410) on the N type GaN layer. The substrate is composed of a P type substrate and an N type substrate.

Description

Vertically structured GaN type light emitting diode device and method of manufacturing the same

1 is a cross-sectional view showing the structure of a vertical gallium nitride-based LED device according to the prior art.

2 is a cross-sectional view showing the structure of a LED package according to the prior art to which a zener diode is applied.

3 is a schematic representation of the circuit in the package shown in FIG.

4 is a cross-sectional view showing the structure of a vertical structure gallium nitride-based LED device according to an embodiment of the present invention.

Figures 5a to 5c is a cross-sectional view for each process for explaining the manufacturing method of the vertical structure gallium nitride based LED device according to an embodiment of the present invention.

6 is a cross-sectional view showing the structure of a package including an LED device according to an embodiment of the present invention.

FIG. 7 is a schematic representation of the circuitry in the package shown in FIG. 6; FIG.

<Description of Symbols for Main Parts of Drawings>

400: LED element 410: n-type contact

420: n-type GaN layer 430: active layer

440: p-type GaN layer 450: p-type electrode

460: bonding layer 470: pn junction structure substrate

470p: p-type substrate 470n: n-type substrate

480: bonding pad

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical structure (vertical electrode type) gallium nitride based (GaN) light emitting diode (hereinafter referred to as "LED") device and a method of manufacturing the same. The present invention relates to a vertical structure gallium nitride-based LED device and a method of manufacturing the same.

In general, gallium nitride-based LEDs grow on sapphire substrates, but these sapphire substrates are hard, electrically nonconducting, and have poor thermal conductivity, reducing the size of gallium nitride-based LEDs, thereby reducing manufacturing costs, or improving light output and chip characteristics. There is a limit to this. In particular, it is important to solve the heat dissipation problem of the LED because a large current is required for the high output of the LED.

As a means for solving this problem, a vertical gallium nitride-based LED device has been proposed in which a sapphire substrate is removed by using a laser lift-off (LLO; hereinafter referred to as 'LLO').

Next, a vertical gallium nitride based LED device according to the prior art will be described in detail with reference to FIG. 1.

1 is a cross-sectional view showing the structure of a vertical gallium nitride-based LED device according to the prior art.

As shown in FIG. 1, a structural support layer 170 is formed at the bottom of the vertical gallium nitride-based LED device 100 according to the related art, and serves to support the LED device 100. The structure support layer 170 is preferably formed using any one of a Si substrate, a GaAs substrate, and a metal layer.

The bonding layer 160 and the p-type electrode 150 are sequentially formed on the structure support layer 170. Here, the p-type electrode 150 is preferably made of a metal having a high reflectance so as to simultaneously serve as an electrode and a reflection role.

On the p-type electrode 150, a p-type GaN layer 140, a GaN / InGaN active layer 130 having a multi quantum well type structure, and an n-type GaN layer 120 are sequentially formed.

An n-type contact 110 is formed on the n-type GaN layer 120. Here, a transparent electrode (not shown) may be further formed between the n-type GaN layer 120 and the n-type contact 110 to improve a current spreading phenomenon.

Since such LED elements can irradiate light with high efficiency at low voltage, they are used in home appliances, remote controls, electronic signs, indicators, and various automation devices. In particular, according to the trend of miniaturization and slimming of information and communication devices, various components such as resistors, capacitors, and noise filters are becoming more compact, and surface-mounting is required to directly mount LED elements to printed circuit boards (PCBs). It is made by a surface mount device (SMD) method.

The SMD type LED package is mainly used as a backlight unit for a liquid crystal display used in a mobile phone. In general, an LED device is known to be vulnerable to electrostatic discharge (ESD) characteristics.

Therefore, in order to compensate for the weakness of the LED device, a means for flowing current in a reverse direction is provided, and in such a way, it is preferable to efficiently respond to static electricity by connecting a zener diode in parallel with the LED device. Doing. That is, the LED and the zener diode are mounted on the cathode and the anode, and the LED and the zener diode are connected to each other with gold (Au) wire or the like to have a parallel structure.

FIG. 2 is a cross-sectional view illustrating a structure of an LED package according to the prior art to which a zener diode is applied, and FIG. 3 is a diagram schematically illustrating a circuit in a package shown in FIG. 2.

As shown in FIG. 2, the LED package according to the related art includes a pair of package electrodes 210 including a cathode 210a and an anode 210b, and the package electrode 210 accommodated therein. A package 220 formed by pre-molding is provided to define the molding material filling space.

The LED element 230 and the zener diode 240 are mounted on the cathode 210a and the anode 210b in the package 220, respectively. Here, although the state in which the LED device 230 of the horizontal structure is mounted is illustrated as an example, the basic configuration of the package is not significantly different even in the vertical structure as described above.

The LED element 230 and the zener diode 240 are electrically connected to the package electrode 210 through a wire 250.

The wire 250 is generally made of gold (Au). The wire 250 may include a first wire 250a electrically connecting the LED element 230 and a cathode 210a, and a second wire electrically connecting the LED element 230 and the anode 210b. And a third wire 250c electrically connecting the zener diode 240 and the cathode 210a.

In this case, in order to secure a bonding area of the wire 250, a bonding pad 270 is formed on the cathode 210a and the anode 210b.

By the wire 250 as described above, the Zener diode 240 is connected in parallel with the LED element 230 as shown in FIG.

In the package 220, a molding material 260 that protects the LED element 230, the zener diode 240, and the wire 250 is filled.

Referring to the operation of the LED package having a structure as described above in detail as follows.

When forward current is applied to the LED package, the current is supplied to the LED device 230 through the anode 210b and the second wire 250b so that the LED device 230 irradiates light. At this time, since the zener diode 240 is in the reverse state, it is electrically open and the LED element is protected in a short state at a predetermined voltage or more.

As such, while the state in which the current having the positive voltage (positive to negative) within a predetermined range is supplied to the LED element 230 is maintained, light emission may be stably maintained.

During this process, if a reverse voltage is applied due to static electricity or the like, the reverse voltage is supplied to the zener diode 240 which is electrically forward. At this time, the LED element 230 is in an electrically open state.

Therefore, when voltage is applied in the reverse direction, the zener diode 240 may bypass the current in a short state to prevent the LED element 230 from being damaged. As described above, the zener diode 240 may be disposed in parallel with the LED element 230 to prevent damage to the LED element 230 due to forward and reverse currents.

However, when the zener diode 240 is applied to enhance the ESD characteristics as described above, a complicated process arises in that the zener diode 240 must be separately mounted in addition to the LED device 230. A part of the light emitted from the 230 is absorbed by the zener diode 240, there is a problem that there is a possibility that the brightness is lowered.

Accordingly, the present invention has been made to solve the above problems, and an object of the present invention is to eliminate the complexity of the process due to the mounting of the zener diode and the possibility of lowering the brightness, while maintaining a vertical gallium nitride-based light emission that can enhance the ESD characteristics The present invention provides a diode device and a method of manufacturing the same.

Vertical structure gallium nitride-based light emitting diode device according to the present invention for achieving the above object,

pn junction structure substrate;

A p-type electrode formed on a predetermined region of the pn junction structure substrate;

A p-type GaN layer formed on the p-type electrode;

An active layer formed on the p-type GaN layer;

An n-type GaN layer formed on the active layer; And

And an n-type contact formed on the n-type GaN layer.

The pn junction structure substrate is characterized in that a p-type substrate and an n-type substrate are sequentially stacked.

The p-type substrate is characterized in that the p-type impurity is doped in any one selected from the group consisting of Si, Ge, InP, SiC, GaAs, GaN, and a ceramic substrate.

In addition, the n-type substrate is characterized in that the n-type impurities are doped in any one selected from the group consisting of Si, Ge, InP, SiC, GaAs, GaN and a ceramic substrate.

The method may further include a bonding pad formed on a predetermined region of the pn junction structure substrate on which the p-type electrode is not formed.

The apparatus may further include a structure support layer formed between the pn junction structure substrate and the p-type electrode.

In addition, the manufacturing method of the vertical structure gallium nitride-based light emitting diode device according to the present invention for achieving the above object,

Sequentially forming an n-type GaN layer, an active layer, and a p-type GaN layer on the sapphire substrate;

Forming a p-type electrode on the p-type GaN layer;

Forming a pn junction structure substrate on the p-type electrode;

Removing the sapphire substrate by an LLO process; And

And forming an n-type contact on the n-type GaN layer from which the sapphire substrate is removed.

Here, the step of forming the pn junction structure substrate,

An n-type substrate and a p-type substrate are sequentially formed on the p-type electrode.

The p-type substrate may be formed by doping p-type impurities into any one selected from the group consisting of Si, Ge, InP, SiC, GaAs, GaN, and ceramic substrates.

The n-type substrate may be formed by doping n-type impurities to any one selected from the group consisting of Si, Ge, InP, SiC, GaAs, GaN, and ceramic substrates.

The pn junction structure substrate may be formed to have a wider width than the p-type electrode, and form a bonding pad on a predetermined region of the pn junction structure substrate exposed by the p-type electrode.

Further, before forming the pn junction structure substrate,

Forming a structural support layer is characterized in that it further comprises.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

Embodiment of the structure of the vertical structure gallium nitride-based LED device

4 is a cross-sectional view showing the structure of a vertical gallium nitride based LED device according to an embodiment of the present invention.

As shown in FIG. 4, a pn junction structure substrate 470 is formed at the bottom of the vertical structure gallium nitride based LED device 400 according to an exemplary embodiment of the present invention. The pn-junction structure substrate 470 is a p-type substrate 470p and an n-type substrate 470n are sequentially stacked. The p-type substrate 470p includes Si, Ge, InP, SiC, GaAs, GaN, and P-type impurities are preferably doped in any one selected from the group consisting of ceramic substrates. The n-type substrate 470n is Si, Ge, InP, SiC, GaAs, similar to the p-type substrate 470p. It is preferable that each of n-type impurities is doped into any one selected from the group consisting of GaN and a ceramic substrate.

The pn junction structure substrate 470 formed by stacking the p-type substrate 470p and the n-type substrate 470n in turn serves as a support for the LED device 400. In addition, since the pn junction is formed on the pn junction structure substrate 470, not only the above-mentioned support role but also a role of the zener diode to strengthen the electrostatic breakdown voltage of the LED device 400 when a voltage is applied in a positive reverse direction. You can even do it.

The bonding layer 460 and the p-type electrode 450 are sequentially formed on a predetermined region of the pn junction structure substrate 470. In general, the bonding layer 460 may be formed of any one or two or more alloys of Au, Sn, In, Ag, Pd, and Cu, and the p-type electrode 450 may serve as an electrode and a reflection at the same time. It is preferable that it is made of a metal having high reflectance.

Although not shown in the drawings, a structural support layer is provided between the pn junction structure substrate 470 and the p-type electrode 450, and more specifically, between the pn junction structure substrate 470 and the junction layer 460. (Not shown) may be further formed. At this time, the structural support layer is preferably any one selected from the group consisting of metal, Si, GaAs and Ge substrates.

The p-type GaN layer 440, the active layer 430, and the n-type GaN layer 420 are sequentially formed on the p-type electrode 450.

An n-type contact 410 is formed on the n-type GaN layer 420. A transparent electrode (not shown) may be further formed between the n-type GaN layer 420 and the n-type contact 410 to improve a current spreading phenomenon.

A bonding pad 480 is formed on a predetermined region of the pn junction structure substrate 470 where the p-type electrode 450 is not formed.

As described above, the vertically structured gallium nitride-based LED device according to the embodiment of the present invention uses a structural support layer used in a general vertically structured gallium nitride-based LED device as a pn junction structure, whereby a zener diode is built into the LED device. LED device can be implemented. Therefore, according to the present invention, there is an effect that can enhance the ESD characteristics of the LED device, while eliminating the complexity of the process and the possibility of lowering the brightness due to the mounting of the existing zener diode.

Embodiment of the manufacturing method of the vertical structure gallium nitride-based LED device

Hereinafter, a method of manufacturing a vertical gallium nitride based LED device according to an embodiment of the present invention as described above will be described.

5A to 5C are cross-sectional views of processes for describing a method of manufacturing a vertical gallium nitride based LED device according to an exemplary embodiment of the present invention.

As shown in FIG. 5A, an n-type GaN layer 420, an active layer 430, and a p-type GaN layer 440 are sequentially grown on the sapphire substrate 500 to form a light emitting structure. Among the light emitting structures, the n-type GaN layer 420 may be formed of an n-type impurity doped GaN layer or a GaN / AlGaN layer, and the active layer 430 may be an InGaN / GaN layer. Well) structure, and the p-type GaN layer 440 may be formed of a GaN layer or a GaN / AlGaN layer doped with p-type impurities like the n-type GaN layer 420.

Next, a p-type electrode 450 is formed on the light emitting structure. The p-type electrode 450 is preferably made of a metal having a high reflectance so as to simultaneously serve as an electrode and a reflective role.

Next, after the bonding layer 460 is formed on the p-type electrode 450, an n-type substrate 470n and a p-type substrate 470p are sequentially formed on the bonding layer 460. Accordingly, the pn junction structure substrate 470 including the n-type substrate 470n and the p-type substrate 470p is formed on the bonding layer 460. Here, the pn junction structure substrate 470 is preferably formed to have a wider width than the p-type electrode 450 in order to secure a bonding area of the wire.

The pn junction structure substrate 470 may be bonded onto the p-type electrode 450 through eutectic bonding or reflow. In this case, the junction layer 460 formed between the pn junction structure substrate 470 and the p-type electrode 450 may be formed of any one or two or more alloys of Au, Sn, In, Ag, Pd, and Cu. Can be formed. As described above, the p-type substrate 470p is preferably formed by doping a p-type impurity into any one selected from the group consisting of Si, Ge, InP, SiC, GaAs, GaN, and ceramic substrates. The n-type substrate 470n is also preferably formed by doping n-type impurities to any one selected from the group consisting of Si, Ge, InP, SiC, GaAs, GaN, and ceramic substrates.

Here, the pn junction structure substrate 470 is preferably bonded onto the p-type electrode 450 via the bonding layer 460, as shown in the drawing, but in some cases, the bonding layer Prior to forming the pn junction structure substrate 470 on 460, a structural support layer (not shown) may be formed, and then the pn junction structure substrate 470 may be further bonded onto the structure support layer. At this time, the structural support layer is preferably any one selected from the group consisting of metal, Si, GaAs and Ge substrates.

As shown in FIG. 5B, the sapphire substrate 500 is removed by an LLO process.

As shown in FIG. 5C, an n-type contact 410 is formed on the n-type GaN layer 420 from which the sapphire substrate 500 is removed. A bonding pad 480 is formed on a predetermined region of the pn junction structure substrate 470 exposed by the p-type electrode 450. Although not shown in the drawing, before forming the n-type contact 410, a transparent electrode (not shown) may be formed on the n-type GaN layer 420 to improve a current spreading phenomenon. .

Package containing vertical gallium nitride based LED device

6 is a cross-sectional view illustrating a structure of a package including an LED device according to an exemplary embodiment of the present invention, and FIG. 7 is a diagram schematically illustrating a circuit in a package illustrated in FIG. 6.

As shown in FIG. 6, a package including an LED device according to an embodiment of the present invention includes a pair of package electrodes 610 formed of a cathode 610a and an anode 610b, and the package electrode 610. It is provided with a package 620 formed by pre-molding to define the molding material filling space, while receiving the inside.

On the cathode 610a in the package 620, an LED device 400 having a built-in zener diode according to an embodiment of the present invention is mounted.

The LED device 400 is electrically connected to the package electrode 610 through a wire 650. Here, the wire 650, the first wire 650a for electrically connecting the n-type contact 410 and the cathode 619a of the LED device 400, and the pn junction structure of the LED device 230 The second wire 650b electrically connects the bonding pad 480 and the anode 610b formed on the substrate 470. In this case, a bonding pad 670 is formed on the cathode 610a and the anode 610b to secure a bonding area of the wire 650.

The inside of the package 620 is filled with a molding material 660 to protect the LED device 400 and the wire 650.

Here, the vertical structure LED device according to the present embodiment as described above, by using a pn junction structure substrate in place of the structure support layer used in the general vertical structure LED device, it is possible to implement the LED device of the built-in type Zener diode. .

That is, according to the present invention, as shown in Fig. 7, the pn junction structure substrate 470 which is a zener diode portion is connected in parallel with the light emitting structure which is an LED portion. At this time, it can be seen that the parallel structure shown in FIG. 7 is structurally identical to the parallel structure shown in FIG. Therefore, in the present invention, by implementing a vertical structure LED device having a built-in zener diode, the effect of enhancing the ESD characteristics of the LED device, while eliminating the complexity of the process and the possibility of brightness degradation due to the mounting of the existing zener diode There is.

Although the preferred embodiments of the present invention have been described in detail above, those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Accordingly, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concept of the present invention as defined in the following claims also fall within the scope of the present invention.

As described above, the present invention can implement an LED device having a built-in zener diode by using a pn junction structure substrate instead of a structure support layer used in a general vertical structure LED device. Therefore, according to the present invention, there is an effect that can enhance the ESD characteristics of the LED device, while eliminating the complexity of the process and the possibility of lowering the brightness due to the mounting of the existing zener diode.

Claims (12)

pn junction structure substrate; A p-type electrode formed on a predetermined region of the pn junction structure substrate; A p-type GaN layer formed on the p-type electrode; An active layer formed on the p-type GaN layer; An n-type GaN layer formed on the active layer; And A vertical gallium nitride based light emitting diode device comprising an n-type contact formed on the n-type GaN layer. The method of claim 1, The pn junction structure substrate is a vertical gallium nitride-based light emitting diode device, characterized in that the p-type substrate and the n-type substrate is laminated in sequence. The method of claim 2, Wherein the p-type substrate is doped with p-type impurities in any one selected from the group consisting of Si, Ge, InP, SiC, GaAs, GaN, and ceramic substrates. The method of claim 2, The n-type substrate is a vertical gallium nitride-based light emitting diode device, characterized in that the n-type impurities are doped in any one selected from the group consisting of Si, Ge, InP, SiC, GaAs, GaN and a ceramic substrate. The method of claim 1, And a bonding pad formed on a predetermined region of the pn junction substrate in which the p-type electrode is not formed. The method of claim 1, And a structure support layer formed between the pn junction structure substrate and the p-type electrode. Sequentially forming an n-type GaN layer, an active layer, and a p-type GaN layer on the sapphire substrate; Forming a p-type electrode on the p-type GaN layer; Forming a pn junction structure substrate on the p-type electrode; Removing the sapphire substrate by an LLO process; And And forming an n-type contact on the n-type GaN layer from which the sapphire substrate has been removed. The method of claim 7, wherein Forming the pn junction structure substrate, And n-type substrate and p-type substrate are sequentially formed on the p-type electrode. The method of claim 8, The p-type substrate is manufactured by doping a p-type impurity into any one selected from the group consisting of Si, Ge, InP, SiC, GaAs, GaN and ceramic substrates. Way. The method of claim 8, The n-type substrate is manufactured by doping a n-type impurity in any one selected from the group consisting of Si, Ge, InP, SiC, GaAs, GaN and ceramic substrates. Way. The method of claim 7, wherein The pn junction structure substrate has a width wider than that of the p-type electrode, and a vertical structure gallium nitride system, characterized in that the bonding pads are formed on a predetermined region of the pn junction structure substrate exposed by the p-type electrode. Method of manufacturing a light emitting diode device. The method of claim 7, wherein Before forming the pn junction substrate, A method of manufacturing a vertical structure gallium nitride-based light emitting diode device, characterized in that it further comprises the step of forming a structural support layer.

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