KR100600373B1 - White light emitting diode and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a white light emitting device and a method of manufacturing the same, and more particularly, by etching both sides of the nitride semiconductor-based blue light emitting device to form a red and green light emitting organic material layer on both sides of the white by the additive mixture of R, G, B The present invention relates to a white light emitting device for emitting light and a method of manufacturing the same. The present invention also relates to a junction down type white light emitting device in which the epitaxial layer is improved by using a substrate such as zinc oxide. Due to these features, the luminous efficiency can be maximized, and the ease of manufacture and the reduction of manufacturing cost of the white light emitting device are realized, and the white color is realized in one cell, so that the microminiaturization and ultra-thin film are realized, and the use of zinc oxide substrate, etc. It provides a significant effect of improving the properties of the layer.

White, light emitting device, organic light emitting

Description

White light emitting device and manufacturing method thereof

1 is a schematic cross-sectional view of a light emitting diode according to the prior art;

2 is a schematic sectional view of a white light emitting diode using a conventional fluorescent material,

3a to 3f are flowcharts of a method of manufacturing a white light emitting diode according to the present invention;

4A to 4D are partial cross-sectional views of a modification of a white light emitting diode according to the present invention.

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

11: substrate 12: conductive substrate

13: N-GaN layer 14: active layer

15: P-GaN layer 16: current diffusion electrode

17: reflective metal layer 18: upper electrode

19: lower electrode 20, 30: green and red light emitting organic material layer

21, 31: organic light emitting layer 22, 32: hole transport layer

23, 33: electron transport layer 24, 34: hole injection layer

25, 35 electron injection layer 40 sidewall passivation

The present invention relates to a white light emitting device and a method of manufacturing the same, and more particularly, by etching both sides of the nitride semiconductor-based blue light emitting device to form a red and green light emitting organic material layer on both sides of the white by the additive mixture of R, G, B The present invention relates to a white light emitting device for emitting light and a method of manufacturing the same.

Recently, light emitting diodes using GaN system are attracting attention as blue and green light emitting diodes, and In _X Ga _1-X N used as active layer has a wide range of energy bandwidth (band gap). It is known to be a substance capable of emitting light in the region. The light emitting diode has a very wide application area such as a display board, a display device, a backlight device, and a light bulb, and the development of high quality light emitting diodes is very important in the trend of increasing and increasing the scope of application.

1 is a schematic cross-sectional view of a light emitting diode according to the related art, in which an N-GaN layer 101, an active layer 102 and a P-GaN layer 103 are sequentially stacked on a sapphire substrate 100. Mesa is etched from the P-GaN layer 103 to a part of the N-GaN layer 101, and the transparent electrode 104 and the P-metal layer 105 are sequentially formed on the P-GaN layer 103. The N-metal layer 106 is formed on the mesa-etched N-GaN layer 101.

The light emitting diode configured as described above is bonded to the molding cup by using an adhesive 108, wire bonding the first lead frame 109a and the N-metal layer 103 connected with one external lead, and the other external lead The second lead frame 109b connected to the P-metal layer 105 is assembled by wire bonding.

Referring to the operation of the light emitting diode as described above, when a voltage is applied through the N and P electrodes, electrons and holes flow from the N-GaN 101 and P-GaN 103 layers into the active layer 102, and electron-hole Recombination occurs, causing light emission. Light emitted from the active layer 102 travels down and up the active layer, and the light propagated upwards is emitted to the outside through the P-GaN 103 layer, and a part of the light propagated upward proceeds to the bottom to the outside of the LED chip. Part of the sapphire substrate is absorbed or reflected by the solder used in the assembly of the light emitting diode chip, and then proceeds up again, and part of the sapphire substrate is absorbed by the active layer again, and then exits through the active layer.

In the conventional structure, since the sapphire substrate having low thermal conductivity is manufactured, it is difficult to smoothly discharge heat generated during operation of the device, thereby degrading the characteristics of the device.

In addition, since the electrode may not be formed at the top and the bottom, as shown in FIG. 1, it is formed in the same direction to remove some regions of the active layer, and accordingly, the light emitting area is reduced to realize a high quality light emitting diode having high brightness. Not only is it difficult, but the number of chips on the same wafer is inevitably reduced, and the manufacturing process is also difficult, resulting in a problem of having to bond twice during assembly.

On the other hand, in such a light emitting diode, various attempts have recently been made to construct a white light emitting light source using the light emitting diode.

In order to obtain white light using the light emitting diode, since the light emitting diode has a monochromatic peak wavelength, three light emitting diodes of R, G, and B should be installed in close proximity, and then lighted and mixed. The brightness and the like are irregular, which makes it difficult to obtain a desired white color.

In addition, since each of the R, G, and B light emitting diodes for implementing white light is manufactured using different materials, the manufacturing of each light emitting diode is complicated and the driving circuit becomes complicated as the driving voltages are different. . In addition, since each light emitting diode is made of a semiconductor, the temperature characteristics are different, and it is difficult to uniformly mix the light generated from each light emitting diode or to change color depending on the use environment, and a lot of spots are generated. There are disadvantages.

In order to solve these disadvantages, a method of applying a resin mold material containing a phosphor to a device portion of a light emitting diode emitting a specific wavelength is used, which causes the phosphor to absorb light emitted from the light emitting diode, By emitting light of the wavelength, it is a method that can implement white light.

That is, when a resin containing a phosphor emitting yellow light is applied to a light emitting diode emitting blue light, the light emitting diode can finally emit white light.

In addition, using a light emitting diode in the ultraviolet band, and blending the R, G, B phosphors (Phosphor), respectively, induction of light emission in the visible light wavelength field is used a system capable of white light emission.

However, when only inorganic yellow phosphors (YAG: Ce) are used, a halo effect occurs due to wavelength separation due to a narrow peak in the blue wavelength region and a broad peak in the yellow wavelength region. Full white implementation has the disadvantage of being difficult.

In addition, most of these methods known to date apply a method using an inorganic phosphor.

FIG. 2 is a conceptual view schematically illustrating a state in which a resin in which inorganic phosphor particles are dispersed is applied to a light emitting diode to implement a white light emitting device according to the prior art, and the light emitting diode is generally bonded and packaged to a reflecting plate of a lead frame. .

At this time, when the light emitting diode 110 emitting blue light is bonded to the cup-shaped reflecting plate 112 of the lead frame 111, the yellow inorganic phosphor particles 113 are formed on the reflecting plate 112 to surround the light emitting diode 110. ) Can be applied to the resin 114 is dispersed to implement white light.

That is, the blue light emitted from the light emitting diode 110 becomes white light through the yellow inorganic phosphor particle 113 to be emitted to the outside.

Herein, since the inorganic phosphor uses a polymer dispersion system, light emission loss due to scattering and absorption of molecular molecules due to dispersion of particles is inevitable. In addition, the surface treatment is necessary to prevent the aggregation phenomenon between the particles, and as time passes, there is a disadvantage in that the efficiency is lowered due to the aggregation of the particles.

In addition, as shown in FIG. 2, when the dispersion is not uniform, uniform light emission cannot be expected, and the higher the content of the phosphor, the more serious the problem becomes, which causes color unevenness, which ultimately lowers the efficiency of the device. There is a problem that acts as a factor.

The present invention has been made to solve the problems described above, a light emitting device for implementing a white light by providing a red light emitting organic material layer and a green light emitting organic material layer on both ends of the nitride semiconductor light emitting device having a blue light emitting structure and a method of manufacturing the same. The present invention relates to a white light emitting device having a superior light efficiency and a simple manufacturing process, and a method of manufacturing the same. In addition, by forming a conductive substrate containing a conductive material, in particular, zinc oxide, on the glass substrate, it is more cost-saving than a sapphire substrate, and when using a substrate containing zinc oxide having a nearly similar lattice constant as GaN, the problem occurs in the existing substrate. An object of the present invention is to provide a white light emitting device and a method of manufacturing the same.

As a preferred aspect for achieving the above object of the present invention,

The present invention provides a light emitting structure including an N-GaN layer, an active layer, and a P-GaN layer, which are sequentially stacked on a central portion of an upper surface of a conductive substrate and whose sidewalls are passivated integrally; A red light emitting organic layer formed on one end of an upper surface of the conductive substrate and in contact with passivation of the sidewall; A green light emitting organic layer formed on the other end of the conductive substrate and in contact with passivation of the sidewall; It provides a white light emitting device comprising a current diffusion electrode formed on the upper surface of the P-GaN layer, the red light emitting organic material layer and the green light emitting organic material layer, and the upper and lower electrodes formed on the upper surface of the current spreading electrode and the conductive substrate, respectively.

In addition, a reflective electrode is further included between the current spreading electrode and the upper electrode, wherein the red light emitting organic material layer or the green light emitting organic material layer is formed of an electron injection layer, an organic light emitting layer and a hole injection layer, an electron injection layer, an electron transport layer, It provides a white light emitting device comprising an organic light emitting layer, a hole transport layer and a hole injection layer.

In addition, the current spreading electrode is a transparent electrode, in particular, ITO, characterized in that the conductive substrate is ZnO, Si, AlN, SiC, GaAs, Cu, W or Mo characterized in that the white light emitting device comprising to provide.

In addition, forming an N-GaN layer, an active layer and a P-GaN layer on the conductive substrate; Etching both ends of the N-GaN layer, the active layer, and the P-GaN layer and then passivating the etched sidewalls; Forming a red light emitting organic layer on the etched end; Forming a green light emitting organic layer on the other end of the etching; Forming a current spreading electrode on an upper surface of the P-GaN layer, the red light emitting organic material layer, and the green light emitting organic material layer; and forming upper and lower electrodes on an upper surface of the current spreading electrode and a conductive substrate, respectively. Provided is a method of manufacturing a white light emitting device.

In addition, by forming a conductive material on the substrate to form a conductive substrate on the substrate; Forming an N-GaN layer, an active layer, and a P-GaN layer on the conductive substrate; Etching both ends of the N-GaN layer, the active layer, and the P-GaN layer and then passivating the etched sidewalls; Forming a red light emitting organic layer on the etched end; Forming a green light emitting organic layer on the other end of the etching; Forming a current spreading electrode on an upper surface of the P-GaN layer, the red light emitting organic material layer, and the green light emitting organic material layer; And removing the substrate by etching the conductive substrate so that the conductive substrate is exposed, and forming upper and lower electrodes on the top of the current spreading electrode and the bottom of the conductive substrate, respectively.

The method may further include forming a reflective metal layer between the current spreading electrode and the upper electrode. The conductive substrate may include ZnO, Si, AlN, SiC, GaAs, Cu, W, or Mo, It provides a method of manufacturing a white light emitting device, characterized in that consisting of.

In addition, the step of forming the red light emitting organic material layer or green light emitting organic material layer is characterized by using a vacuum deposition, chemical vapor deposition method, spin coating method, or a screen printing method, the step of forming the red light emitting organic material layer or green light emitting organic material layer. Provided is a method of manufacturing a white light emitting device, characterized in that formed by laminating with an electron injection layer, an organic light emitting layer and a hole injection layer, or laminated with an electron injection layer, an electron transport layer, an organic light emitting layer, a hole transport layer and a hole injection layer. do.

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

3A to 3F are detailed cross-sectional views illustrating a method of manufacturing a white light emitting diode according to the present invention with reference to the procedure.

First, as shown in FIG. 3A, a method well known in the art, such as a process of MOCVD, is performed on the substrate 11 to grow a conductive material to form the conductive substrate 12 on the substrate 11. do. Thereafter, an N-GaN layer 13, an active layer 14, and a P-GaN layer 15 are formed on the conductive substrate 12. Thereafter, heat treatment is performed at 600 ° C. for about 20 minutes to activate impurities in the P-GaN layer 15 to form a blue light emitting structure (FIG. 3A).

The N-GaN layer 13 is an N-wave guide layer, and the active layer 14 may be selected as long as it is used in the nitride-based semiconductor light emitting device of the art. In _x Ga _1-x N or Al _x Ga _1-x N and the like, preferably a multi-quantum well structure is preferred. The P-GaN layer 15 is a P-wave guide layer.

Since the substrate 11 is removed by a process to be described later, any substrate that can form an epitaxial layer may be selected without limitation. Glass substrates, sapphire substrates or nitride semiconductor substrates may be selected, and glass substrates are best used in view of cost reduction and ease of substrate removal. The substrate 11 is sometimes omitted and may form an epitaxial layer directly on the conductive substrate 12.

The conductive substrate 12 may be selected if the thermal conductivity and the electrical conductivity are excellent, and particularly, the epitaxial layer and the lattice constant are similar. It is preferably made of ZnO, Si, AlN, SiC, GaAs, Cu, W or Mo, or a combination thereof. Among them, ZnO is most preferred because the lattice constant is similar to GaN. In the case of a semiconductor material, a dopant may be added.

Next, as shown in FIG. 3B, both ends of the N-GaN layer 13, the active layer 14, and the P-GaN layer 15 are etched, and then the etched sidewall is passivated.

The etching method may be wet or dry etching, but dry etching is preferable, and RIE may be used. Since the etching method is well known in the art, a detailed description thereof will be omitted.

The reason for passivating the etched sidewall is to prevent the epi layer from shorting when the light emitting organic layer is formed on the etched sidewall. Therefore, an insulating material is used as the passivation material. Preferably, it is preferable to use silicon oxide, silicon nitride, etc. which are excellent in heat resistance, oxidation resistance, etc., and an insulation resin etc. can also be used. The passivation method can use an existing method without limitation. That is, a vapor deposition method, a coating method or a printing method can be used.

Next, as shown in FIG. 3C, the red light emitting organic layer 20 is formed on the etched end and the green light emitting organic layer 30 is formed on the etched other end.

The light emitting organic layers 20 and 30 are applied to the passivated sidewalls of the etched region by vacuum deposition, chemical vapor deposition, and polymers using spin coating or printing. Since the white light emitting device of the present invention implements white light by additive mixing of R, G, and B, the white light emitting device may realize white color by a simple method of controlling the coating amount of the light emitting organic layer.

The red light emitting organic layer 20 or the green light emitting organic layer 30 may be formed of a single organic light emitting layer. In this case, a material in which the organic light emitting layer can play a role of electron transport and hole transport is preferable.

As the material of the organic light emitting layer, any material capable of emitting red or green when an electric field is applied may be selected and used, and since the organic light emitting layer is sufficiently known in the art, it may be selected among them (see Patent Publication No. 10-1998-64694, 10-2004-98055, 10-2004-94078, 10-1998-37808, etc.).

Next, as illustrated in FIGS. 3D to 3F, a current spreading electrode 16 is formed on the P-GaN layer 15, the red light emitting organic layer 20, and the green light emitting organic layer 30. The substrate 11 is etched and removed so that the conductive substrate 12 is exposed (the step of etching and removing the substrate 11 is not required when the substrate 11 is not used), and the current The upper electrode 18 and the lower electrode 19 are formed on the diffusion electrode 16 and the back surface of the conductive substrate 12, respectively.

In the above structure, it is more preferable to form the reflective metal layer 17 between the current spreading electrode 16 and the upper electrode 18.

The removing of the substrate 11 may be performed before forming the current spreading electrode 16.

The current spreading electrode 16 may be selected as long as the electric field is formed evenly in the light emitting area. Preferably, the transparent electrode is preferable, and ITO is the best.

The method of removing the substrate 11 may be selected from wet and dry etching methods, and may be removed by a conventional laser lift-off method according to the type of substrate. Most preferably, RIE dry etching is preferred.

The reflective metal layer 17 is formed to maximize luminous efficiency, and is not limited as long as it is a material for reflecting light, but Ag, Al, Pt, Au, Ni, Ti, ATO (SbO ₂ doped with Sb) and ITO It is preferred that any one or more of them are included.

This completes the white light emitting device according to the present invention.

The white light emitting device of the present invention prepared as described above is maximized the luminous efficiency because the light loss is significantly reduced compared to the white light emitting device using a conventional phosphor, and etching both ends of the nitride semiconductor light emitting structure to form an organic light emitting material As white is realized, it is easy to manufacture and reduction of manufacturing cost. Since white is realized in one cell, it is possible to realize miniaturization and ultra thin film, and to use junction down type structure and zinc oxide substrate. The characteristics of the epi layer are improved

The present invention is not limited to the above embodiments and is included in the scope of the present invention as long as it can be deduced by those skilled in the art.

4A to 4D are diagrams showing one form of modification of the white light emitting device of the present invention.

That is, as illustrated in FIGS. 4A and 4B, the red light emitting organic layer 20 or the green light emitting organic layer 30 may be formed of electron transport layers 23 and 33, organic light emitting layers 21 and 31, and hole transport layers 22 and 32. Modifications can be made.

In addition, as shown in FIGS. 4C and 4D, the red light emitting organic layer 20 or the green light emitting organic layer 30 includes electron injection layers 25 and 35, electron transport layers 23 and 33, and organic light emitting layers 21 and 31. ), Hole transport layers 22 and 32 and hole injection layers 24 and 34 may also be modified.

The electron injection layers 25 and 35, the electron transport layers 23 and 33, the hole transport layers 22 and 32, and the hole injection layers 24 and 34 are formed in the same manner as the above-described method of forming the light emitting organic layer. The detailed description will be omitted.

When the electron transporting layers 23 and 33 and the hole transporting layers 22 and 32 are formed, electrons injected into the light emitting layers 21 and 31 are blocked at the interface with the hole transporting layer and are no longer moved and trapped in the organic light emitting layer. -Improved space recombination efficiency increases light efficiency.

In addition, the hole injection layers 24 and 34 and the electron injection layers 25 and 35 serve to lower the energy barrier to enable more effective hole and electron injection.

The materials of the electron injection layers 25 and 35, the electron transport layers 23 and 33, the hole transport layers 22 and 32, and the hole injection layers 24 and 34 are widely known in the art, and are not limited thereto. It can be used without reference (see Publication Nos. 10-2004-94078, 10-1998-64694, 10-2004-98055, 10-2004-94078, 10-1998-37808, etc.) .

The above modification is more preferable because the light efficiency of the light emitting organic layer increases.

As described above, the present invention forms a red and green light emitting organic layer on both sides by etching both sides of the nitride semiconductor-based blue light emitting device to implement white light emission by additive mixing of R, G, B, The efficiency can be maximized, and the ease of manufacturing and reduction of manufacturing cost of the white light emitting device is realized, and the white color is realized by one cell, so that the microminiaturization and ultra-thin film are realized, and the use of junction down type structure and zinc oxide substrate It provides a remarkable effect of improving the properties of the epi layer.

Claims (16)

A blue nitride semiconductor light emitting structure including an N-GaN layer, an active layer, and a P-GaN layer sequentially stacked on a central portion of an upper surface of a conductive substrate and integrally passivated with sidewalls; A red light emitting organic layer formed on one end of an upper surface of the conductive substrate and in contact with the passivation of the sidewall; A green light emitting organic layer formed on the other end of the upper surface of the conductive substrate and in contact with the passivation of the sidewall; A current diffusion electrode formed on an upper surface of the P-GaN layer, the red light emitting organic material layer, and the green light emitting organic material layer; and A white light emitting device comprising an upper and a lower electrode formed on the current diffusion electrode and the bottom of the conductive substrate, respectively. The white light emitting device of claim 1, further comprising a reflective electrode between the current spreading electrode and the upper electrode. The white light emitting device of claim 1, wherein the red light emitting organic material layer or the green light emitting organic material layer comprises an electron injection layer, an organic light emitting layer, and a hole injection layer. The white light emitting device of claim 1, wherein the red light emitting organic material layer or the green light emitting organic material layer comprises an electron injection layer, an electron transport layer, an organic light emitting layer, a hole transport layer, and a hole injection layer. The white light emitting device according to claim 1 or 2, wherein the current spreading electrode is ITO. The white light emitting device of claim 1 or 2, wherein the conductive substrate comprises ZnO, Si, AlN, SiC, GaAs, Cu, W, or Mo. Forming an N-GaN layer, an active layer, and a P-GaN layer over the conductive substrate; Etching both ends of the N-GaN layer, the active layer, and the P-GaN layer and then passivating the etched sidewalls; Forming a red light emitting organic layer on the etched end; Forming a green light emitting organic layer on the other end of the etching; Forming a current spreading electrode on an upper surface of the P-GaN layer, the red light emitting organic material layer, and the green light emitting organic material layer; and And forming upper and lower electrodes on the upper side of the current spreading electrode and the back surface of the conductive substrate, respectively. Forming a conductive substrate on the substrate by forming a conductive material on the substrate; Forming an N-GaN layer, an active layer, and a P-GaN layer on the conductive substrate; Etching both ends of the N-GaN layer, the active layer, and the P-GaN layer and then passivating the etched sidewalls; Forming a red light emitting organic layer on the etched end; Forming a green light emitting organic layer on the other end of the etching; Forming a current spreading electrode on an upper surface of the P-GaN layer, the red light emitting organic material layer, and the green light emitting organic material layer; Etching and removing the substrate to expose the conductive substrate; and And forming upper and lower electrodes on the current spreading electrode and the bottom of the conductive substrate, respectively. The method of claim 7 or 8, further comprising forming a reflective metal layer between the current spreading electrode and the upper electrode. The method of claim 7 or 8, wherein the conductive substrate comprises ZnO, Si, AlN, SiC, GaAs, Cu, W, or Mo, or a combination thereof. The method of claim 7, wherein the forming of the red light emitting organic layer or the green light emitting organic layer is performed by vacuum deposition, chemical vapor deposition, spin coating, or screen printing. . The method of claim 7, wherein the forming of the red light emitting organic material layer or the green light emitting organic material layer is formed by stacking an electron injection layer, an organic light emitting layer, and a hole injection layer. The method of claim 7 or 8, wherein the forming of the red light emitting organic material layer or the green light emitting organic material layer is formed by stacking an electron injection layer, an electron transport layer, an organic light emitting layer, a hole transport layer and a hole injection layer. Method of manufacturing a light emitting device. The method of manufacturing a white light emitting device according to claim 7 or 8, wherein the current spreading electrode is a transparent electrode. 15. The method of claim 14, wherein the current spreading electrode is ITO. The method of claim 8, wherein the substrate is a glass substrate, a sapphire substrate, or a nitride semiconductor substrate.

Images