KR20070008995A - Light emitting diodes and manufacturing method - Google Patents

Abstract

 The present invention relates to a light emitting diode and a method of manufacturing the same. More particularly, the light emitting diode of the present invention includes a plurality of N-GaN layers formed on a substrate and a plurality of ultraviolet rays each having different wavelengths on the N-GaN layer. Comprising a multi-layer active layer comprising an active layer and a P-GaN layer formed on the multi-layer active layer, the light emitting diode manufacturing method of the present invention is an N-GaN layer, a first active layer, a second active layer, a third active layer and A stacking step of sequentially stacking P-GaN layers to form a light emitting structure, an etching step of mesa etching the light emitting structure to expose a portion of the top surface of the N-GaN, and an upper portion of the mesa-etched N-GaN layer. And forming a P electrode on the non-etched upper portion of the P-GaN layer.

 Therefore, according to the light emitting diode according to the present invention and a method of manufacturing the same, excellent light efficiency is obtained by using a multilayer active layer that emits ultraviolet rays having an optimal efficiency wavelength of each phosphor, and when the multilayer active layers are continuously stacked, the light output is greatly increased. You can. In addition, the present invention is not limited by space by implementing a multi-layered active layer on a single LED chip, it is easy to control the light output by configuring each active layer to be driven independently, it is possible to adjust the color temperature of the white light.

Description

Light emitting diodes and method of manufacturing the same {LED and process for fabricating the same}

1 is a cross-sectional view showing an embodiment of a light emitting diode according to the present invention;

2 is a cross-sectional view showing another embodiment of a light emitting diode according to the present invention;

3 is a cross-sectional view showing another embodiment of a light emitting diode according to the present invention;

4 is a process chart showing one embodiment of a method of manufacturing a light emitting diode according to the present invention;

5 is a schematic cross-sectional view showing a light emitting diode manufactured by one embodiment of a method of manufacturing a light emitting diode according to the present invention;

6 is a process chart showing another embodiment of the method of manufacturing a light emitting diode according to the present invention;

7 is a schematic cross-sectional view showing a light emitting diode manufactured by another embodiment of the method of manufacturing a light emitting diode according to the present invention;

8 is a schematic cross-sectional view showing a light emitting diode manufactured by another embodiment of a method of manufacturing a light emitting diode according to the present invention.

 The present invention relates to a light emitting diode and a method of manufacturing the same, and more particularly, to provide a light emitting diode having a multi-layered active layer to increase the manufacturing efficiency by configuring a single diode chip rather than a combination of individual diode chips, each having a different wavelength The present invention provides a light emitting diode including a multi-layer active layer generating ultraviolet light and a light emitting diode in which each active layer is independently driven so as to have a light efficiency having excellent light efficiency and various color temperatures.

      In general, the white light emitting device is widely used as a backlight of the lighting device or the display device. As such a white light emitting device, a method of combining blue, red, and green light emitting diodes made of individual light emitting diodes and a method of using phosphors are known.

      First, a white light emitting device of a combination of individual light emitting diodes is mounted on a single printed circuit board through a wire, each of the already completed blue, red and green light emitting diodes, so that the light of different colors emitted from each light emitting diode Are synthesized to produce white light.

     When the individual light emitting diodes are combined as described above, excellent color can be obtained. However, since each LED chip must be manufactured separately, not only the manufacturing cost increases but also the current of each LED chip needs to be adjusted in order to obtain desired white light, and there is a problem in that a complicated circuit configuration is required. In addition, since space limitations occur in using a plurality of light emitting diode chips, there is an obstacle in increasing the resolution of the display.

      Next, as a method of manufacturing a white light emitting device using a phosphor, there are a method using a blue light emitting diode and a method using an ultraviolet light emitting diode.

      In the case of using a blue light emitting device, blue light is wavelength-converted to white light using a YAG (yittrium aluminum garnet) phosphor. That is, the blue wavelength generated from the blue light emitting diode may excite the YAG phosphor and finally emit white light.

      For example, when power is applied to the blue light emitting element and blue light is emitted from the InGaN-based blue light emitting diode, part of the blue light excites the YAG phosphor. At this time, the YAG phosphor is synthesized with other blue light directly emitted from the InGaN blue LED, thereby finally emitting white light.

      When the wavelength modulation of the phosphor through the blue light emitting diode is used as described above, the manufacturing process is simpler and the manufacturing cost is reduced as compared with the case of combining the individual LEDs. However, there is a disadvantage that the light efficiency is reduced or the color correction index is lowered when the phosphor is excited.

On the other hand, the method using the ultraviolet light emitting device is similar to the method using the blue light emitting diode. That is, ultraviolet rays generated from the ultraviolet light emitting diodes may excite individual phosphors (eg, R, G, and B) to finally emit white light. However, the above method has a disadvantage in that the light efficiency is low because the most efficient excitation light source is different for each phosphor.

The present invention is to solve the above problems,

It is to provide a light emitting diode having a multi-layered active layer to increase the manufacturing efficiency by configuring a single diode chip rather than a combination of individual diode chips.

Another object of the present invention is to provide a light emitting diode having excellent light efficiency, including a multilayer active layer that generates ultraviolet rays having different wavelengths, respectively.

Another object of the present invention is to provide a light emitting diode in which each active layer is independently driven to have various color temperatures.

      The light emitting diode proposed by the present invention includes a N-GaN layer formed on a substrate, a multi-layer active layer including a plurality of active layers each emitting ultraviolet rays having different wavelengths on the N-GaN layer, and a P-GaN layer formed on the multi-layer active layer. It is configured to include.

      Each active layer emits ultraviolet rays to excite individual phosphors (eg, R, G, B). Since individual phosphors are made of different materials, they have different light efficiency. The feature of the present invention is that the wavelength of the ultraviolet light emitted from each active layer is configured differently depending on the light efficiency of the individual phosphors in view of the above.

      As the light emitting diode proposed by the present invention includes a multi-wavelength multilayer active layer as described above, it is possible to solve the problem of lowering the light efficiency of the single-wavelength ultraviolet diode of the prior art. In addition, it is possible to emit multi-wavelength ultraviolet rays from a single diode chip instead of a plurality of diode chips, thereby not being limited in space. In addition, when the multilayer active layer is continuously stacked, the light output can be more than doubled.

      Another light emitting diode proposed by the present invention includes a first N-GaN layer sequentially formed on a substrate, a first active layer capable of emitting first ultraviolet light, a first P-GaN layer, and a second capable of emitting second ultraviolet light. And an active layer, a second N-GaN layer, a second P-GaN layer, a third active layer capable of emitting third ultraviolet rays, and a third N-GaN layer.

      The present invention is configured to include a conductive layer between each active layer to drive each of the aforementioned active layers independently.

      A method of manufacturing a light emitting diode according to the present invention includes a first step of sequentially forming an N-GaN layer, a first active layer, a second active layer, a third active layer, and a P-GaN layer on a substrate to form a light emitting structure, wherein N Mesa etching the light emitting structure so that a part of the upper surface of the GaN layer is exposed; and forming an N electrode on the mesa-etched N-GaN layer, and forming a P electrode on the P-GaN layer. Forming step.

Another method of manufacturing the light emitting diode proposed by the present invention includes a first N-GaN layer, a first active layer, a first P-GaN layer, a second active layer, a second N-GaN layer, a second P-GaN layer, A stacking step of sequentially stacking a third active layer and a third N-GaN layer to form a light emitting structure; a first etching step of mesa etching the light emitting structure to expose a portion of an upper surface of the first N-GaN layer; A second etching step of mesa etching the light emitting structure so that a part of the top surface of the first P-GaN layer is exposed, and a third etching step of mesa etching the light emitting structure so that a part of the top surface of the second N-GaN layer is exposed And a fourth etching step of mesa etching the light emitting structure to expose a portion of an upper surface of the second P-GaN layer, and an upper portion of the third N-GaN layer and an upper portion of the mesa-etched first and second N-GaN layers. Forming first to third N-electrodes, and forming a first on the mesa-etched first and second P-GaN layers 2 consists of an electrode forming step of forming a P electrode.

The present invention is to form a conductive layer connected to the driving electrode between each active layer so that each active layer can be driven independently.

Hereinafter, with reference to the accompanying drawings will be described in detail the technical features of the present invention. The invention can be better understood by the examples, the following examples are for illustrative purposes of the invention and are not intended to limit the scope of protection defined by the appended claims.

      1, an N-GaN layer 5 formed on a substrate 6 and a first active layer capable of emitting a first ultraviolet ray on the N-GaN layer, as shown in FIG. 1. 4), the multilayer active layer in which the second active layer 3 capable of emitting the second ultraviolet ray and the third active layer 2 capable of emitting the third ultraviolet ray are sequentially formed and the P-GaN layer formed on the multilayer active layer (1). It is configured to include).

      The substrate may be made of sapphire, GaN, or SiC material. In this embodiment, Mg-GaN and Si-GaN were used as the P-GaN and N-GaN layers, but any metal capable of P doping and N doping. Even dopants can be used.

The active layer is made of InGaN, it is possible to control the wavelength of the ultraviolet light emitted by adjusting the content ratio of indium. Each of the active layers may be formed by varying the composition ratio of indium so as to emit ultraviolet rays of 378 to 382 nm, 398 to 402 nm, and 348 to 352 nm, which are optimal excitation wavelengths of the respective phosphors. The B, G, and R phosphors currently in use are (Sr, Ca, Ba, Mg) ₁₀ (PO ₄ ) ₆ Cl: Eu ²⁺ , ZnS: Cu, Al, and L ₂ O ₂ S: Eu ^{3+, respectively} . This is because the excitation wavelength with the highest light efficiency for each phosphor is 380 nm, 400 nm, and 350 nm, respectively.

     As in the present embodiment, when emitting ultraviolet rays of different wavelengths, it is preferable that an active layer emitting a longer wavelength is disposed close to the substrate so that ultraviolet rays generated from the active layer can be easily transmitted upward.

The present invention may further include a P-AlGaN layer formed between the multilayer active layer and the P-GaN layer to further increase the efficiency of the carrier, and an N-AlGaN layer further formed between the N-GaN layer and the multilayer active layer. .

     As another embodiment of the light emitting diode according to the present invention, as shown in Figure 2, the multilayer active layer is formed of a structure (9) in which the unit structure of the first active layer-the second active layer-the third active layer is repeated do. Such a structure can raise the light output of the diode more than twice.

      In another embodiment of the light emitting diode according to the present invention, as shown in FIG. 3, the first N-GaN layer 51 sequentially formed on the substrate 6 and the first active layer 4 capable of emitting the first ultraviolet light 4. ), The first P-GaN layer 11, the second active layer 3 capable of emitting the second ultraviolet light, the second N-GaN layer 52, the second P-GaN layer 12, and the third ultraviolet light. And a third active layer 2 and a third N-GaN layer 53 capable of emitting light.

      The present invention is configured such that each of the active layers is driven independently. The diode may control light emission of each active layer, and a white light emitting device having various color temperatures may be realized by the combination of light emission.

In the above embodiment, in order to increase the efficiency of the carrier, a P-AlGaN layer is further formed between each active layer and each P-GaN layer, and an N-AlGaN layer is further formed between each active layer and each N-GaN layer. desirable.

      As shown in FIG. 4, an embodiment of the method of manufacturing a light emitting diode according to the present invention includes a laminating step S 10, an etching step S 20, and an electrode forming step S 30. 5 is a schematic cross-sectional view of an ultraviolet light emitting diode manufactured by the above method.

       First, the lamination step S 10 is performed on the substrate 6 by using an N-GaN layer 5, a first active layer 4, a second active layer 3, a third active layer 2 and a P-GaN layer 1. Sequentially stacked to form a light emitting structure. As described above, the substrate may be made of sapphire, GaN, or SiC material, and the P-GaN layer and the N-GaN layer may be used as a dopant of any metal capable of P doping and N doping. The active layer is preferably formed by varying the composition ratio of indium so as to emit ultraviolet rays of 378 to 382 nm, 398 to 402 nm, and 348 to 352 nm, which are optimum excitation wavelengths of the respective phosphors.

      In the etching step S 20, the light emitting structure is mesa-etched so that a part of the top surface of the N-GaN layer is exposed. This is to form an N electrode in the N-GaN layer in a later step.

      Mesa etching is an optional etch that projects from above adjacent areas leaving only a flat portion of the original surface and is used to prevent the expansion of electrically active material into the mesa area. Since mesa etching is well known, a detailed description thereof will be omitted.

      In the electrode forming step (S 30), an N electrode 7 is formed on the mesa-etched N-GaN layer, and a P electrode 8 is formed on the P-GaN layer. Each electrode is formed by depositing a resistive metal.

      As another embodiment of the method of manufacturing a light emitting diode according to the present invention, as shown in Figure 6, the lamination step (S 100), the first etching step (S 220), the second etching step (S 240), the third etching step (S 260), the fourth etching step (S 280) and the electrode forming step (S 300) is made. 7 is a schematic cross-sectional view of an ultraviolet light emitting diode manufactured by the above method.

      The embodiment is for manufacturing an ultraviolet light emitting diode configured to drive each of the active layers independently. First, the stacking step (S 100) is performed on the substrate 6, the first N-GaN layer 51, the first active layer ( 4), the first P-GaN layer 11, the second active layer 3, the second N-GaN layer 52, the second P-GaN layer 12, the third active layer 2 and the third N -GaN layer 53 is sequentially stacked to form a light emitting structure.

      The first etching step S 220 is to secure a region in which the first N electrode 71 is to be formed, and mesa-etches the light emitting structure to expose a portion of the top surface of the first N-GaN layer.

      The second etching step S 240 is to secure a region in which the first P electrode 81 is to be formed, and mesa-etches the light emitting structure so that a part of the top surface of the first P-GaN layer is exposed.

      The third etching step (S 260) is to secure a region in which the second N electrode 72 is to be formed, and mesa-etches the light emitting structure to expose a portion of the top surface of the first N-GaN layer.

      The fourth etching step (S 280) is to secure a region in which the second P electrode 82 is to be formed, and mesa-etches the light emitting structure so that a part of the top surface of the second P-GaN layer is exposed.

      In the forming of the electrode (S 300), first to third N electrodes are formed on the third N-GaN layer, the mesa-etched first and second N-GaN layers, and the mesa-etched first and second P- layers. First and second P electrodes are formed on the GaN layer. The ultraviolet light emitting diode manufactured by the above method has a first active layer by connecting a second N electrode and a first P electrode, a second active layer by connecting a third N electrode and a first P electrode, and a first N electrode and a first N electrode. The third active layers may be independently driven by connecting 2 P electrodes.

      In the method of manufacturing the light emitting diode according to the present invention, as shown in FIG. 8, when the substrate 61 of N-GaN or N-SiC material is used, the substrate may function as an N electrode, and thus, the third N Mesa etching of a part of the GaN layer from the GaN layer to the first N-GaN layer is omitted, and the first N electrode 710, the second N electrode 720, and the first P electrode ( 81, the second P electrode 82 is formed.

There are various methods for adjusting the light output of the light emitting diode manufactured by the method as described above.

First, the number of wells of each active layer is controlled.

That is, when the luminance of the first active layer is high or the color tone is strong, the number of wells of the first active layer is reduced and the number of wells of the second active layer is increased.

In this way, the light output can be adjusted by adjusting the number of wells of each active layer.

Second, light output can be controlled by injecting different currents into each active layer.

Third, the light output can be adjusted by combining the above two methods.

Therefore, the light emitting diode of the present invention can realize the wavelength of all visible light region.

 According to the light emitting diode according to the present invention and its manufacturing method, it has excellent light efficiency by using a multilayer active layer that emits ultraviolet rays of the optimum efficiency wavelength of each phosphor, and when the multilayer active layer is continuously stacked, the light output can be greatly increased. have.

Next, the present invention is not limited in space by implementing a multilayer active layer on a single diode chip.

In addition, the present invention is configured so that each active layer is driven independently, it is easy to adjust the light output, it is possible to adjust the color temperature of white light.

Claims (11)

       An N-GaN layer formed on the substrate;       A multilayer active layer comprising a plurality of active layers each emitting ultraviolet rays having different wavelengths on the N-GaN layer; And  A light emitting diode comprising a P-GaN layer formed on the multilayer active layer. The method of claim 1, The multilayer active layer is a light emitting diode, characterized in that consisting of the first to third active layer. The method of claim 1, Light-emitting diodes, characterized in that the multilayer active layer is formed by stacking two or more consecutively. The method of claim 1, A P-AlGaN layer is further formed between the multilayer active layer and the P-GaN layer. The N-AlGaN layer is further formed between the N-GaN layer and the multi-layer active layer.       A first N-GaN layer, a first active layer capable of emitting first ultraviolet light, a first P-GaN layer, a second active layer capable of emitting second ultraviolet light, a second N-GaN layer, and a second P on the substrate A light emitting diode comprising a GaN layer, a third active layer capable of emitting third ultraviolet rays, and a third N-GaN layer sequentially stacked. The method of claim 4, wherein An N-AlGaN layer is further formed between the first N-GaN layer and the first active layer, between the second active layer and the second N-GaN layer, and between the third active layer and the third N-GaN layer, respectively. A light emitting layer further comprising a P-AlGaN layer formed between the first active layer and the first P-GaN layer, between the first P-GaN layer and the second active layer, and between the second P-GaN layer and the third active layer, respectively. diode. The method according to any one of claims 1 to 6, The first to the third active layer is a light emitting diode, characterized in that to sequentially emit ultraviolet light of a long wavelength from a short wavelength. A lamination step of sequentially forming an N-GaN layer, a first active layer, a second active layer, a third active layer, and a P-GaN layer on the substrate to form a light emitting structure; An etching step of mesa etching the light emitting structure so that a part of the top surface of the N-GaN is exposed; And Forming an N electrode on the mesa-etched N-GaN layer and forming a P electrode on the non-etched upper portion of the P-GaN layer. The first N-GaN layer, the first active layer, the first P-GaN layer, the second active layer, the second N-GaN layer, the second P-GaN layer, the third active layer and the third N-GaN layer are sequentially formed on the substrate. Laminating step of forming a light emitting structure by laminating with; A first etching step of mesa etching the light emitting structure so that a part of the top surface of the first N-GaN is exposed; A second etching step of mesa etching the light emitting structure to expose a portion of the upper surface of the first P-GaN layer; A third etching step of mesa etching the light emitting structure to expose a portion of the upper surface of the second N-GaN layer; A fourth etching step of mesa etching the light emitting structure to expose a portion of the upper surface of the second P-GaN layer; Forming first to third N electrodes on the third N-GaN layer and the mesa-etched first and second N-GaN layers, and first and second P electrodes on the mesa-etched first and second P-GaN layers. Method of manufacturing a light emitting diode consisting of an electrode forming step of forming a. A first N-GaN layer, a first active layer, a first P-GaN layer, a second active layer, a second N-GaN layer, a second P-GaN layer, a third active layer and a third N-GaN layer are formed on the conductive substrate. A laminating step of sequentially laminating to form a light emitting structure; A first etching step of mesa etching the light emitting structure to expose a portion of an upper surface of the first P-GaN layer; A second etching step of mesa etching the light emitting structure so that a part of the top surface of the second N-GaN layer is exposed; A third etching step of mesa etching the light emitting structure so that a part of the top surface of the second P-GaN layer is exposed; First and second N electrodes are formed on the third N-GaN layer and the mesa etched second N-GaN layer, and first and second P electrodes are formed on the mesa etched first and second P-GaN layers. Method of manufacturing a light emitting diode comprising an electrode forming step. The method according to claim 9 or 10, The light emitting structure further includes an N-AlGaN layer between the first N-GaN layer and the first active layer, between the second active layer and the second N-GaN layer, and between the third active layer and the third N-GaN layer, respectively. , A P-AlGaN layer is formed between the first active layer and the first P-GaN layer, between the first P-GaN layer and the second active layer, and between the second P-GaN layer and the third active layer, respectively. Method of manufacturing a light emitting diode.

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