KR100907223B1 - Vertical Light Emitting Diode And Fabrication Method Thereof - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical type light emitting diode and a method of manufacturing the same, wherein a semiconductor layer is laminated on a light emitting diode through a bonding metal layer, and filled with metal therein to have a via hole for electrically communicating the light emitting diode with the outside. One ceramic substrate is included. A method of manufacturing such a light emitting diode, comprising the steps of: bonding a ceramic substrate having a via hole filled with a metal on top of a light emitting diode formed of individual elements on a substrate; Separating.

According to the present invention, by mounting a ceramic substrate having a via hole instead of a conductive substrate on top of the light emitting diode, the thermal conductivity is very excellent and the reliability of the device is improved by minimizing the thermal expansion coefficient between the gallium nitride semiconductor layer and the ceramic substrate. There is an effect to get.

Light Emitting Diode, Semiconductor Layer, Via Hole, Ceramic, Gallium Nitride, Thermal Expansion Coefficient

Description

Vertical Light Emitting Diode And Fabrication Method Thereof}

The present invention relates to a vertical type light emitting diode and a method of manufacturing the same, and more particularly, a bonding metal layer is bonded to an upper portion of a light emitting diode on which semiconductor layers are stacked, and filled with metal to communicate the light emitting diode with the outside. A method of manufacturing a light emitting diode, comprising: bonding a light emitting diode including a ceramic substrate having a via hole to a ceramic substrate; and bonding a ceramic substrate having a via hole on the substrate; and removing the substrate and separating the individual light emitting diode elements. It is about.

Compound semiconductor light emitting devices that convert electrical signals to light using characteristics of compound semiconductors, that is, light emitting devices such as LEDs (Light Emitting Diodes) or laser diodes (LDs), are used in applications such as lighting, optical communication, and multiple communication. It is a trend that is being studied and put into practical use in.

In general, light emitting devices are grown or deposited in a vertical structure on a substrate. In particular, a light emitting device having an insulator sapphire substrate and having a semiconductor light emitting layer on which a semiconductor layer in another region and an active layer as an active region are deposited thereon is formed with all electrodes on the top of the device and is coupled by flip chip or wire bonding, or FIG. 1. As in the method of the present invention, a vertical light emitting diode combined with a conductive wafer substrate is formed of a bonding metal layer.

A cross-sectional view schematically illustrating a conventional method of manufacturing a vertical vertical light emitting diode is shown in FIGS. 1A to 1F.

Referring to FIGS. 1A to 1F, first, an n-type semiconductor layer 102, an active layer 103, and a gallium nitride of a buffer layer 101, a gallium nitride (GaN) -based semiconductor are formed on a sapphire substrate 100 in FIG. 1A. The p-type semiconductor layer 104 made of (GaN) -based semiconductor is formed sequentially.

Then, the trench portion 105 is formed by etching so that the light emitting structure has individual device regions (FIG. 1B).

Next, as shown in FIG. 1C, the p-type electrode and the reflective film 106 are formed on the p-type semiconductor layer 104.

A conductive substrate such as silicon (Si), gallium arsenide (GaAs), silicon carbide (SiC), or the like is bonded or deposited on the p-type electrode and the reflective film 106.

Thereafter, the sapphire substrate 100 is removed using a laser, and then etching is performed to expose the n-type semiconductor layer 102 surface of the removed sapphire substrate surface.

Next, as shown in FIG. 1F, when the n-type electrode 108 is formed on the n-type semiconductor layer 102 and separated into individual chips, a plurality of vertical light emitting diodes are simultaneously obtained.

In general, according to the conventional vertical light emitting diode manufacturing method, a conductive substrate is generally adhered to the p-type electrode by using an adhesive or a conductive material is directly deposited on the p-type electrode before removing the sapphire substrate.

However, when a conductive substrate such as silicon (Si) or gallium arsenide (GaAs) is used, heat dissipation efficiency is not good because the substrate is not excellent in thermal conductivity, and there is a high possibility of deterioration of device characteristics when a high current is applied.

In addition, when the substrate is bonded, cracks may occur due to a difference in thermal expansion coefficient with the light emitting structure, thereby damaging the device. On the other hand, when the conductive material is directly deposited, the conductive substrate must be cut in order to separate it into individual chips. However, a conductive substrate such as copper (Cu) is very difficult to cut, and thus a cutting process for chip separation is added according to the properties of the conductive substrate. As a result, manufacturing costs are increased and overall process time is delayed.

An object of the present invention is to remove the sapphire substrate having a low thermal conductivity and to mount a ceramic substrate with a via hole in order to solve the problems of the conventional vertical light emitting diode and the manufacturing method as described above, the best characteristics in the ratio of thermal conductivity The present invention provides a light emitting diode having an improved reliability of a device by minimizing a thermal expansion coefficient between a gallium nitride semiconductor layer and a ceramic substrate.

Another object of the present invention is to provide a method for economically manufacturing a light emitting diode having improved thermal conductivity and reliability of the light emitting diode without further adding a complicated process as compared to a conventional vertical light emitting diode manufacturing method.

The vertical light emitting diode of the present invention for achieving the above object is bonded to the upper portion of the light emitting diode in which the semiconductor layer is laminated via a bonding metal layer, and filled with a metal inside and has a via hole for electrically communicating the light emitting diode with the outside. It includes a ceramic substrate.

The side surface of the light emitting diode is surrounded by a protective thin film layer and filled with a polymer organic compound layer in the side space between the individual light emitting diode devices. The protective thin film layer may be formed of silicon oxide (SiO ₂ ) or silicon nitride (Si ₃ N ₄ ), and the polymer organic compound is preferably an epoxy resin.

The light emitting diode may include a semiconductor layer, an active layer, and an electrode of different types of nitride semiconductor compounds.

In addition, the light emitting diode is an individual device further comprising a protective thin film layer and a polymer organic compound layer made of silicon oxide (SiO ₂ ) or silicon nitride (Si ₃ N ₄ ) on the side of the trench-etched semiconductor layer. It is done.

Bonding of the ceramic substrate may be performed through a bonding metal layer on the light emitting diode, and the bonding metal layer may include a seed metal layer and a conductive adhesive layer.

In the present invention, the seed metal layer is silver (Ag), nickel (Ni), aluminum (Al), titanium (Ti), palladium (Pd), platinum (Pt), ruthenium (Ru), gold (Au), rhodium ( Rh), iridium (Ir), tantalum (Ta), copper (Cu) may be any one or more metal selected from the group consisting of.

In addition, the conductive adhesive layer is a palladium indium compound (Pd / In), palladium tin compound (Pd / Sn), tin tin compound (Au-Sn), tin (Sn), indium (In), gold (Au), gold and silver It may be selected from the group consisting of a compound (Au / Ag), lead tin compound (Pb-Sn).

In the present invention, the metal filled in the via hole may be selected from the group consisting of copper (Cu), copper (CuW), aluminum (Al), and gold (Au).

In addition, the ceramic substrate may be made of an insulator material, and preferably has a thermal conductivity of 100 W / mK or more.

Accordingly, the ceramic substrate may be any one or more materials selected from boron nitride (BN), alumina, aluminum nitride (AlN), and beryllium oxide (BeO).

In the present invention, a conductive contact metal may be coupled to an upper portion of the via hole of the ceramic substrate, and is coupled to an upper portion of the filling metal of the via hole.

At least one surface of the light emitting diode may include a texturing structure. The at least one surface of the light emitting diode may have a concave-convex structure by texturing a surface opposite to a surface to which a ceramic substrate having a via hole is coupled.

The vertical light emitting diode manufacturing method of the present invention for achieving the above object comprises the step of bonding a ceramic substrate having a via hole filled with a metal on top of the light emitting diode formed of a separate element on the substrate, and removing the substrate do.

Thereafter, the light emitting diode individual elements to which the ceramic substrate is bonded can be cut out and separated.

The light emitting diode formed of the individual device may be formed by dividing the light emitting diode on the substrate in a trench.

Prior to the bonding of the ceramic substrate in the present invention, a protective thin film layer made of silicon oxide (SiO ₂ ) or silicon nitride (Si ₃ N ₄ ) on the side of each of the light emitting diodes, and a polymer organic compound layer in sequence Forming to surround the light emitting diode may be further included.

In the present invention, the method may further include forming an electrode and a reflective film on the LEDs to which the ceramic substrate is bonded.

The reflective film may be formed of indium tin oxide (ITO), indium zinc oxide (IZO), indium oxide, tin oxide, silicon oxide (SiO 2), silicon nitride (Si 3 N 4), aluminum oxide, titanium oxide, silver (Ag), nickel (Ni ), Aluminum (Al), titanium (Ti), palladium (Pd), platinum (Pt), ruthenium (Ru), gold (Au), rhodium (Rh), iridium (Ir).

After forming the P-type electrode and the reflective film on the light emitting diode structure, forming a protective thin film layer on the side of the light emitting diode structure can reduce the current loss to the side of the light emitting device. In addition, filling a polymer organic compound layer such as an epoxy resin in the trench region of the light emitting structure may prevent cracking of the light emitting device in the step of removing the growth substrate.

In the present invention, after removing the substrate, the method may further include forming a texturing structure on at least one surface of the light emitting diode, and for this purpose, patterning is performed by nanoimprinting, lithography, or laser holography. Dry etching, or wet chemical etching without patterning, can be used.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. In adding reference numerals to the components of the following drawings, it is known that the same components, even if displayed on the other drawings to have the same reference numerals as possible and determined to unnecessarily obscure the subject matter of the present invention Detailed description of functions and configurations will be omitted.

2A through 2I are cross-sectional views illustrating a method of manufacturing a vertical light emitting diode according to an exemplary embodiment of the present invention.

Referring to FIG. 2A, a buffer layer 201, an n-type semiconductor layer 202, an active layer 203, and a p-type semiconductor layer 204 are sequentially stacked on a substrate 200 for growing a light emitting device. The sapphire substrate is mainly used as the substrate for light emitting device growth.

Since the light emitting device is preferably a nitride semiconductor light emitting device, the semiconductor layer may be a nitride compound semiconductor layer such as gallium nitride.

In this case, the n-type semiconductor layer may be grown once more on the p-type semiconductor layer 204.

The light emitting device including the n-type and p-type semiconductor layers may be grown in a plurality of layers.

Referring to FIG. 2B, after stacking the light emitting devices, a trench 205 is formed to separate the stacked light emitting structures into a plurality of devices. The trench may be formed by giving an inclination to the side surface of the light emitting structure, and the shape may have a trapezoidal shape when viewed in a side cross-sectional view.

It would be desirable to be separated into individual light emitting elements having sides that are inclined structures, but may also have a rectangular cross-sectional structure.

2C, a p-type electrode and a reflective film 206 are formed on the p-type semiconductor layer 204 of the individually separated LEDs. The p-type electrode and the reflective film function as a reflective ohmic contact layer.

The reflective ohmic contact layer 206 may include a conductive metal such as silver (Ag) or aluminum (Al), and various structures may be selected.

Preferably ITO, In ₂ O ₃ , SnO ₂ , SiO ₂ , Si ₃ N ₄ , Al ₂ O ₃ , TiO ₂ , Ag, Ni, Al, Cu, Ti, Pd, Pt, Ru, Au, Rh, Ir It is preferably made of a material selected from the group consisting of a combination of and comprises at least one layer.

As a next step according to an embodiment of the present invention, the protective film layer 207 is formed on the side of the light emitting structure by using an insulator material such as SiO ₂ , Si ₃ N ₄ . In the case of the passivation layer, current flow to the side of the light emitting structure may be blocked to improve electrical characteristics of the device.

Then, in FIG. 2E, the epoxy resin 208 is filled in the trench region, which is an empty space between the individual light emitting devices, to easily bond the bonding metal on the p-type semiconductor layer side.

The epoxy resin is a material representing a polymer organic compound, and is not necessarily limited thereto, and may serve to facilitate bonding of bonding metals and to provide durability by filling empty spaces between individual devices.

Filling the trench region 205 with epoxy may be excluded for convenience of the process. However, preferably, the step of removing the growth substrate 200 may cause cracking (cracking) in the light emitting device formed of the compound semiconductor layer such as gallium nitride (GaN), and thus it is preferable to fill the epoxy.

As a next step, a bonding metal layer 209 is formed on the p-type electrode and the reflective film 206 in FIG. 2F.

The bonding metal layer 209 serves as a medium for bonding the ceramic substrate 210 in which the via hole is formed and the light emitting structure.

The bonding metal layer 209 is a seed metal for bonding with the via hole-formed ceramic substrate 210 and includes at least one of Ag, Ni, Al, Ti, Pd, Pt, Ru, Au, Rh, Ir, Ta, Cu, and Ta. It may include a seed metal layer comprising at least one layer and a conductive adhesive layer made of a material selected from the group consisting of Au-Sn, Sn, In, Au-Au, Pd-Sn and Pd-In.

On the other hand, the via hole formed ceramic substrate 210 is preferably made of an insulator material having a thermal conductivity of 100 W / mK or more, and such representative materials include AlN, BN and the like.

Preferably, it is preferable to use AlN which is excellent in thermal conductivity for the price and has a small difference in coefficient of thermal expansion with a gallium nitride (GaN) layer, and which can be used in a large area.

Referring to FIG. 2G, the growth substrate 200 is removed from the light emitting device of the present invention.

Preferably, as shown in FIG. 2G, after bonding the ceramic substrate on which the via hole is formed and the light emitting structure, the sapphire substrate 200 used as the growth substrate layer is removed using a laser beam.

After removing the substrate, one surface is cleaned and etched to expose the n-type semiconductor layer 202 so that the n-type electrode can be coupled onto the n-type semiconductor layer.

FIG. 2H illustrates a process of coupling the n-type electrode 212 to the surface of the exposed n-type semiconductor layer 202.

As shown in FIG. 2I, the final process is a process of separating each individual light emitting device.

As a method of cutting into individual light emitting diodes, a conventional method known by a person skilled in the art may be used. Preferably, the plurality of ceramic substrates having the via holes separated by a dicing process or a scribing process are separated into individual elements. The vertical structure of the light emitting diode is obtained.

In order to cut durablely without breaking the light emitting device in the cutting process, a material such as an epoxy resin should be filled between each individual light emitting device.

3A to 3E have been described step by step for a method of manufacturing a ceramic substrate having a via hole provided in a vertical light emitting diode according to an embodiment of the present invention.

Referring to FIG. 3A, first, a via hole 311 having a space penetrating up and down is formed in the ceramic substrate 310.

In FIG. 3B, a seed metal layer 312 is formed on the bottom surface of the ceramic substrate 310 to facilitate coupling of the metal layer to be filled in the via hole in the following process and the ceramic substrate.

The material constituting the seed metal layer is silver (Ag), nickel (Ni), aluminum (Al), titanium (Ti), palladium (Pd), platinum (Pt), ruthenium (Ru), gold (Au), rhodium ( Rh), iridium (Ir), tantalum (Ta) and copper (Cu).

3C, the filling metal layer 313 is formed to cover the bottom surface of the via hole and the seed metal layer 312 penetrating the top and bottom of the ceramic substrate.

In the case of the metal filled in the via hole, the metal is preferably made of a material selected from copper (Cu), copper (CuW), aluminum (Al), and gold (Au).

Next, referring to FIG. 3D, when the metal filled in the via hole is protruded to the top of the ceramic substrate and filled, the metal plate is subjected to a flattening process to flatten and even the top surface of the ceramic substrate. The planarization process is not necessarily timed, and may be any time after forming the contact metal layer later, as can be seen in FIG. 3E.

A bonding metal layer 314 is formed on the filling metal layer 313 of the lower surface of the ceramic substrate.

The bonding metal layer may be sequentially stacked when the light emitting diodes are sequentially formed on the growth substrate, when the light emitting diodes are formed as individual light emitting devices. As shown in an embodiment of the present invention, a ceramic substrate having a via hole is provided. In the process of forming the bonding metal layer may be formed.

Referring to FIG. 3E, after the flattening process of the filling metal layer 313 formed on the ceramic substrate is performed, a contact metal layer 315 is formed on the filling metal 313 of the ceramic substrate.

4 is a cross-sectional view illustrating a method of manufacturing a vertical light emitting diode according to still another embodiment of the present invention.

The previous process for forming the light emitting diode having the structure as shown in FIG. 4 has been described above with reference to FIGS. 2A to 2I.

However, after the upper surface of the n-type semiconductor layer 402 exposed by removing the sapphire substrate 200 is cleaned, a texturing 420 structure is formed on the n-type semiconductor layer.

The texturing structure may be formed by using a regular pattern or a method using random patterning.

As a method of using a regular pattern, a method using nanoimprinting, electron beam lithography, and laser holography is preferable. After the regular pattern is formed, a texturing structure may be formed on the n-type semiconductor layer through dry etching.

As a method using random patterning, dry etching is performed after forming nano-sized clusters through heat treatment of metals such as silver (Ag), nickel (Ni), gold (Au), platinum (Pt), and palladium (Pd). Through this, a random texturing structure can be formed.

Alternatively, random texturing may be formed by a wet chemical etching method. After etching by using a potassium hydroxide (KOH) aqueous solution, a random texturing structure may be formed on the n-type semiconductor layer.

As described above, the present invention has been described with reference to a preferred embodiment of the present invention, but those skilled in the art can vary the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. It will be appreciated that modifications and variations can be made.

As described above, according to the present invention, by removing the sapphire substrate having low thermal conductivity and mounting the ceramic substrate having the via hole filled with the filling metal, the semiconductor layer and the ceramic substrate of the light emitting device have the best characteristics in the thermal conductivity. Since the coefficient of thermal expansion can be minimized, there is an effect of improving the reliability of the vertical LED device.

In addition, the ceramic substrate can be produced in a large area and can be easily separated into individual elements through the trench forming process, so that it can be applied to various light emitting devices, and in the future, high quality light emitting diodes having improved thermal conductivity and reliability are provided. There is an advantage to lower the cost of production.

Vertical light emitting diodes according to an embodiment of the present invention, by removing the sapphire used as a substrate of the light emitting diode and mounting a ceramic substrate having a via hole, not only has the best characteristics in the thermal conductivity of the price ratio, but also nitriding, instead of the conductive substrate A nitride semiconductor light emitting device having a vertical structure which improves reliability of a device by minimizing a thermal expansion coefficient between a gallium layer and a ceramic substrate.

Specifically, a method of manufacturing a vertical light emitting device according to the present invention may include forming a plurality of light emitting structures on a light emitting structure forming substrate, forming a first electrode and a reflective film on a first conductive nitride semiconductor layer, and trenches of respective light emitting diodes. Forming a protective film to protect regions, sides and top surfaces, bonding the ceramic substrate and the light emitting structure, removing sapphire used as a light emitting diode substrate, forming an electrode on the sapphire removing surface, cutting the ceramic substrate It can be configured to separate into separate chips.

1A to 1F are cross-sectional views illustrating a method of manufacturing a vertical light emitting diode according to an exemplary embodiment of the prior art.

2A to 2I are cross-sectional views illustrating a method of manufacturing a vertical light emitting diode according to an embodiment of the present invention.

3A to 3E are cross-sectional views illustrating a method of manufacturing a ceramic substrate having via holes formed in a vertical light emitting diode according to an exemplary embodiment of the present invention.

4 is a cross-sectional view of a vertical light emitting diode according to another embodiment of the present invention.

{Description of symbols for main parts of the drawing}

100,200: substrate 101,201: buffer layer

102,202,402 n-type semiconductor layer 103,203,403 active layer

104,204,404: p-type semiconductor layer 105,205: trench portion

106,206,406: p-type electrode and reflecting film 107: conductive substrate

108,212 n-type electrode 207,407 protective thin film layer

208,408 Epoxy resin 209,314,409 Bonding metal layer

210,310,410: Ceramic substrate 211,311,411: Via hole

312: seed metal layer 313: filled metal layer

420: texturing structure

Claims (16)

A bonding metal layer formed on an upper portion of the light emitting diode, wherein the semiconductor layers are stacked and electrodes are disposed on upper and lower portions of the semiconductor layer, respectively; And One or more via holes bonded to an upper portion of the bonding metal layer and filled with at least one metal selected from the group consisting of copper (Cu), copper (CuW), aluminum (Al), and gold (Au) and bonded to an upper portion of the via hole. A vertical light emitting diode comprising a ceramic substrate having a conductive contact metal. The method of claim 1, The semiconductor layer of the light emitting diode is an n-type semiconductor layer, an active layer, and a p-type semiconductor layer made of a nitride semiconductor compound, wherein the n-type semiconductor layer includes an n-type electrode and the p-type semiconductor layer. Vertical light emitting diodes characterized in that. The method of claim 1, The light emitting diode is an individual device further comprising a protective thin film layer and a polymer organic compound layer made of silicon oxide (SiO ₂ ) or silicon nitride (Si ₃ N ₄ ) on the side of the trench-etched semiconductor layer. Vertical light emitting diodes. The method of claim 1, And the bonding metal layer comprises a seed metal layer and a conductive adhesive layer. The method of claim 4, wherein The seed metal layer is silver (Ag), nickel (Ni), aluminum (Al), titanium (Ti), palladium (Pd), platinum (Pt), ruthenium (Ru), gold (Au), rhodium (Rh), iridium (Ir), tantalum (Ta), copper (Cu) of the vertical light emitting diode, characterized in that any one or more metal selected from the group consisting of. The method of claim 4, wherein The conductive adhesive layer may be made of palladium indium compound (Pd / In), palladium tin compound (Pd / Sn), tin compound (Au-Sn), tin (Sn), indium (In), gold (Au), gold and silver compound ( Au / Ag), lead tin compound (Pb-Sn) is a vertical light emitting diode, characterized in that any one or more selected from the group consisting of. delete The method of claim 1, And wherein the ceramic substrate is an insulator material having a thermal conductivity of 100 W / mK or more. The method of claim 1, The ceramic substrate is a vertical light emitting diode, characterized in that any one or more materials selected from boron nitride (BN), alumina (Alumina), aluminum nitride (AlN), beryllium oxide (BeO). delete The method of claim 1, And a bottom surface of the light emitting diode includes a texturing structure. Stacking a plurality of different types of semiconductor layers on a substrate; Etching the semiconductor layer to separate the plurality of individual devices, and forming an electrode on an upper surface of the individual devices to form a plurality of light emitting diodes; Bonding a ceramic substrate having via holes filled with metal on top of the plurality of light emitting diodes; Removing the substrate; Forming an electrode on a lower surface of the individual device from which the substrate is removed; And The method of manufacturing a vertical light emitting diode comprising the step of separating the plurality of light emitting diodes into individual chips. The method of claim 12, Before bonding the ceramic substrate, the light emitting diode is formed by sequentially forming a protective thin film layer made of silicon oxide (SiO ₂ ) or silicon nitride (Si ₃ N ₄ ), and a polymer organic compound layer on each side of the light emitting diode. Method of manufacturing a vertical light emitting diode further comprising the step of surrounding. The method of claim 12, The method of manufacturing a vertical type light emitting diode further comprising the step of forming a reflective film in addition to the electrode formed on the semiconductor layer. The method of claim 14, The reflective film may be formed of indium tin oxide (ITO), indium zinc oxide (IZO), indium oxide, tin oxide, silicon oxide (SiO 2), silicon nitride (Si 3 N 4), aluminum oxide, titanium oxide, silver (Ag), nickel (Ni ), At least one selected from the group consisting of aluminum (Al), titanium (Ti), palladium (Pd), platinum (Pt), ruthenium (Ru), gold (Au), rhodium (Rh), and iridium (Ir) Method of manufacturing a vertical light emitting diode, characterized in that consisting of a material. The method of claim 12, After removing the substrate further comprises the step of forming a texturing structure on the lower surface of the individual device, the texturing structure is formed by dry etching after patterning by nanoimprinting, lithography, or laser holography method A method of manufacturing a vertical light emitting diode, characterized in that it is formed by a wet chemical etching method that does not or patterning.

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