KR20180126796A - Method for manufacturing color light-emitting diode using wafer bonding and vertically deposited color light-emitting diode - Google Patents

Abstract

The present invention relates to a manufacturing method for a color light-emitting diode (LED). The manufacturing method for a color LED includes: a step of forming a first light emitting layer formed of a matter based on gallium nitride (GaN) and including a first multi-quantum well layer having a first band gap, on a first substrate optically transparent in an epitaxial growth method; a step of forming a second light emitting layer formed of a matter based on gallium phosphorous (GaP) or Aluminum indium gallium phosphorous (Al(In)GaP) and including a second multi-quantum well layer having a second band gap narrower in comparison with the first band gap, on a second substrate in the epitaxial growth method; a step of bonding the second light emitting layer to the first light emitting layer using a bonding layer including one or more oxide layers with a refractive index different from that of the second light emitting layer; a step of patterning the second light emitting layer before the step of bonding or after the step of bonding; and a step of patterning the first light emitting layer bonded to the second light emitting layer patterned. According to the present invention, the manufacturing method can form a full color LED by one-time transfer and has an easy process as alignment for transfer is unnecessary. The manufacturing method also can miniaturize the color LED and require low power consumption since the light emitting display of each color does not separately occupy an area.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of manufacturing a color light emitting diode (LED) using wafer bonding, and a vertically stacked color light emitting diode

Embodiments relate to a method of manufacturing a color light emitting diode (LED) through wafer bonding and a vertical stacked type LED, more specifically, to a method of stacking light emitting layers of respective colors vertically, To a full color LED.

2. Description of the Related Art [0002] Display devices have been miniaturized due to technological advancement, and wearable devices and flexible devices have recently received a great deal of attention, and demand for ultra-small display devices is increasing. In the future, a holographic display, a virtual reality, or augmented reality technology is more widely used, and it is expected that the need for an ultra-small display device with high resolution will increase.

A light-emitting diode (LED) is attracting attention as such a small-sized display device. However, the display device to which the LED is applied up to now has a limitation in miniaturization due to severe power consumption, which is a factor that deteriorates the market growth of wearable devices and the like. Further, it is difficult to reduce the pixel pitch of the LED to a certain level or less in the current technology, and there is a problem that when applied to a wearable device, the pixel is visible and causes dizziness of the user.

FIG. 1 is a graph showing a conventional LED characteristic for use.

1, in the case of a conventional organic light-emitting diode (OLED) or a quantum dot light-emitting diode (QLED), it is easy to downsize the pixel pitch by reducing the pixel pitch. However, The brightness per unit area is limited and it is difficult to reduce power consumption. Conventional inorganic LEDs applied to general illumination or white illumination have relatively low power consumption, but there is no technology capable of realizing the pixel pitch necessary for an ultra-small display device based on an inorganic LED.

2A is a diagram showing an LED manufactured according to the prior art.

2A, a conventional inorganic LED includes an LED layer 2 for emitting blue or ultraviolet rays on a substrate 1, and a light emitting layer 2 for emitting light of white light through the phosphor 3 Respectively. At this time, the color is implemented by a color filter (4) having each color area located on the LED. However, such conventional techniques require additional color filter design, are complicated in structure and are difficult to be miniaturized. Since the output must be increased in consideration of light loss occurring in the phosphor 3 and the color filter 4, .

FIG. 2B is a view showing an LED manufactured according to another conventional technique. FIG.

2B, in order to reduce the pixel pitch in the inorganic LED, LEDs 6, 7 and 8 of different colors are manufactured on a separate substrate and then transferred to the final substrate 5 to manufacture a color LED There is a way. However, even in such a conventional technique, since the LEDs of several million pixels are required to be transferred to the correct positions by color, there is a limit in downsizing. Since each color LED is manufactured on different substrates, 3 times) is required for the transfer process and the process yield is low.

Japanese Patent Application Laid-Open No. 10-2011-0110607

According to one aspect of the present invention, a full color light-emitting diode (LED) can be realized by one-time transfer by eliminating the disadvantages of the conventional art described above, And a light emitting device of each color does not occupy an area separately, thereby making it possible to provide a method of manufacturing a color LED in which color LEDs can be downsized and power can be reduced, and a vertical stacked color LED and a semiconductor device including the same.

A method of fabricating a color light-emitting diode (LED) according to one embodiment includes forming a first multi-quantum well layer having a first band gap on an optically transparent first substrate in an epitaxial growth manner Forming a first light emitting layer made of gallium nitride (GaN) based material; (GaP) or aluminum indium gallium phosphide (Al (In)) and a second quantum well layer having a second bandgap narrower than the first bandgap in an epitaxial growth manner on a second substrate, Forming a second light emitting layer made of GaP based material; Bonding the second light emitting layer onto the first light emitting layer using a bonding layer including at least one oxide layer having a different refractive index from the second light emitting layer; Patterning the second light emitting layer before or after the bonding step; And patterning the first light emitting layer bonded to the patterned second light emitting layer.

In one embodiment, the step of patterning the second light-emitting layer is performed after the bonding step, and before the step of patterning the second light-emitting layer after the bonding step, the step of patterning the second substrate located on the second light- And removing by etching.

In one embodiment, the step of forming the second light emitting layer includes forming a sacrificial layer between the second substrate and the second multiple quantum well layer, wherein patterning the second light emitting layer comprises: . Further, the method of manufacturing a color LED further includes etching the sacrificial layer to remove the second substrate before the step of patterning the first light emitting layer after the joining step.

In one embodiment, the first multiple quantum well layer comprises indium gallium nitride (InGaN) and gallium nitride (GaN).

In one embodiment, the first substrate comprises a sapphire.

In one embodiment, the second multiple quantum well layer comprises aluminum indium gallium phosphide (Al (In) GaP).

In one embodiment, the second substrate comprises gallium arsenide (GaAs).

A method of manufacturing a color LED according to an exemplary embodiment of the present invention is characterized in that before the bonding step, a third multiple quantum well having a third bandgap narrower than the first bandgap and wider than the second bandgap, Forming a third light emitting layer comprising a gallium nitride (GaN) based material including a well layer. At this time, in the bonding step, the second light emitting layer is bonded to the first light emitting layer through the third light emitting layer.

In one embodiment, the step of forming the third light emitting layer includes forming the third light emitting layer in an epitaxial growth manner on the second light emitting layer.

In one embodiment, the forming of the third light emitting layer includes: forming the third light emitting layer on a third substrate; Bonding the third light emitting layer onto the first light emitting layer; And removing the third substrate with the third light emitting layer bonded to the first light emitting layer.

In one embodiment, the third multiple quantum well layer comprises indium gallium nitride and gallium nitride.

The method of manufacturing a color LED according to an exemplary embodiment of the present invention further includes forming at least one electrode electrically contacted with the patterned first light emitting layer or the patterned second light emitting layer.

A vertical stacked color LED according to an embodiment includes an optically transparent substrate; A first light emitting layer on the substrate, the first light emitting layer comprising a first multi quantum well layer having a first bandgap and made of a gallium nitride (GaN) based material; And a second multiple quantum well layer having a second bandgap narrower than the first bandgap, the second multi quantum well layer being disposed on the first emission layer and being formed of gallium phosphide (GaP) or aluminum indium gallium phosphide (Al (In) GaP) A second light emitting layer made of a material of And a bonding layer disposed between the first emitting layer and the second emitting layer and including at least one oxide layer having a different refractive index from the second emitting layer.

In one embodiment, each of the first light emitting layer and the second light emitting layer further comprises at least one semiconductor layer located on one side of the first multiple quantum well layer or the second multiple quantum well layer.

The vertical multi-layered color LED according to an exemplary embodiment of the present invention may include a third multi-layered multi-layer LED having a third band gap narrower than the first band gap and having a third band gap larger than the second band gap, And a third light emitting layer comprising a quantum well layer and made of a gallium nitride (GaN) based material.

The vertical stacked color LED according to an embodiment further includes at least one electrode electrically connected to the first light emitting layer or the second light emitting layer for applying electric power.

A semiconductor device according to an embodiment includes a vertical stacked color LED according to the above-described embodiments.

According to the method of manufacturing a color light-emitting diode (LED) according to an aspect of the present invention, by laminating light-emitting elements of different colors in a vertical direction on one substrate, And it is advantageous that the device can be miniaturized and the power consumption can be reduced because the light emitting device of each color does not occupy an area separately.

In the color LED according to one aspect of the present invention, the light is emitted in the direction of the light emitting device having a narrower bandgap than the light emitting device having a narrow bandgap considering the bandgap of each color light emitting device, There is an advantage that the problem of light absorption loss in the apparatus can be prevented.

FIG. 1 is a graph showing a conventional light-emitting diode (LED) characteristic.
2A and 2B are diagrams illustrating LEDs manufactured according to the prior art.
3 is a perspective view of a vertical stacked color LED according to one embodiment.
4A to 4F are cross-sectional views showing respective steps of a method of manufacturing a color LED according to an embodiment.
5A to 5C are cross-sectional views showing some steps of a method of manufacturing a color LED according to another embodiment.
6A to 6F are cross-sectional views showing respective steps of a method of manufacturing a color LED according to another embodiment.
7A and 7B are cross-sectional views showing some steps of a method of manufacturing a color LED according to another embodiment.
8A to 8D are cross-sectional views showing some steps of a method of manufacturing a color LED according to another embodiment.
9A to 9E are cross-sectional views showing some steps of a method of manufacturing a color LED according to another embodiment.
10A and 10B are photographs showing surface characteristics before and after surface polishing, respectively.
11 is a graph showing bandgap characteristics of a vertical stacked color LED according to an embodiment.
FIG. 12 is a graph illustrating the reflectance of each layer according to the structure of a junction layer in a vertical stacked color LED according to an exemplary embodiment. Referring to FIG.

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

Where reference in the specification to "above " another part, it may be directly on the other part or be accompanied by another part therebetween. In contrast, when a section is referred to as being "directly above" another section, no other section is involved.

The terms first, second and third, etc. are used herein to describe various portions, components, regions, layers and / or sections, but are not limited thereto. These terms are only used to distinguish any moiety, element, region, layer or section from another moiety, moiety, region, layer or section. Thus, a first portion, component, region, layer or section described below may be referred to as a second portion, component, region, layer or section without departing from the scope of the present invention.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular forms as used herein include plural forms as long as the phrases do not expressly express the opposite meaning thereto. Means that a particular feature, region, integer, step, operation, element and / or component is specified and that the presence or absence of other features, regions, integers, steps, operations, elements, and / It does not exclude addition.

The term " below ", "above ", and the like, which denote relative space in this specification, can be used to more easily describe the relationship to other parts of a part shown in the drawings. These terms are intended to include other meanings or acts of the apparatus in use, as well as intended meanings in the drawings. For example, when inverting a device in the figures, certain parts that are described as being "below" other parts are described as being "above " other parts. Thus, an exemplary term "below" includes both up and down directions. The device can be rotated 90 degrees or rotated at different angles, and the term indicating the relative space is interpreted accordingly.

Unless otherwise defined, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Commonly used predefined terms are further interpreted as having a meaning consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or very formal meanings unless defined otherwise.

3 is a perspective view of a vertical stacked color light-emitting diode (LED) according to an embodiment.

3, the LED according to the present embodiment includes a substrate 100, a first light emitting layer 10 disposed on the substrate 100, and a second light emitting layer 20 disposed on the first light emitting layer 10 . In one embodiment, the LED further comprises a third emitting layer 30 positioned between the first emitting layer 10 and the second emitting layer 20. Also in one embodiment, the LED further comprises an electrode 40 for applying power to these luminescent layers.

The substrate 100 supports the first to third light emitting layers 10, 20, and 30. The substrate 100 is optically transparent so that the light 50 emitted from the first to third light emitting layers 10, 20 and 30 can be transmitted through the substrate 100 and output for display. For example, the substrate 100 may be made of sapphire, but is not limited thereto.

The first light emitting layer 10 is an inorganic light emitting layer that is grown on the substrate 100 in an epitaxy manner. On the other hand, the second light emitting layer 20 is an inorganic light emitting layer that is grown on another substrate (not shown) and then transferred onto the first light emitting layer 10. The first light emitting layer 10 is made of a gallium nitride (GaN) based material and the second light emitting layer 20 is made of gallium phosphide (GaP) or aluminum indium gallium phosphide (Al (In) GaP) based material.

Each of the first luminescent layer 10 and the second luminescent layer 20 may have a multi quantum wall (MQW) layer. The multiple quantum well structure is formed by forming a multi-layered well structure in which an active layer (or a light emitting layer) and an insulating layer (or a barrier layer) are alternately stacked, It will be understood by those skilled in the art that a detailed description thereof will be omitted. Further, each of the first light emitting layer 10 and the second light emitting layer 20 may further include at least one semiconductor layer located on one side or both sides of the multiple quantum well layer.

Light generated from the first light emitting layer 10 is output through the substrate 100 while light generated from the second light emitting layer 20 is output through the first light emitting layer 10 and the substrate 100. At this time, in order to prevent light generated from the second light emitting layer 20 from being absorbed by the first light emitting layer 10 and causing no loss, a bandgap of the multiple quantum well structure of the first light emitting layer 10 The first band gap) is wider than the band gap (or the second band gap) of the multiple quantum well structure of the second light emitting layer 20. For example, the first light emitting layer 10 may include a multiple quantum well structure of indium gallium nitride (InGaN) and GaN as a light emitting device that emits green or blue light, and the second light emitting layer 20 may include red And may include aluminum indium gallium phosphide (Al (In) GaP) as a light emitting element.

If the color LED further includes the third light emitting layer 30, the bandgap of the multiple quantum well structure of the third light emitting layer 30 (or the third light emitting layer 30 of the third light emitting layer 30) 3 band gap) is narrower than the first band gap and wider than the second band gap. In addition, the third light emitting layer 30 is made of a GaN-based material like the first light emitting layer 10. For example, the first light emitting layer 10 is a light emitting element that emits blue light, the third light emitting layer 30 is a light emitting element that emits green light, and the second light emitting layer 20 is a light emitting element that emits red light. Lt; / RTI > At this time, the first light emitting layer 10 and the third light emitting layer 30 include a multiple quantum well structure of InGaN and GaN, respectively. However, the color of light emitted according to the composition ratio of InGaN and GaN can be made different as described above have.

A bonding layer (not shown) for bonding exists between the first light emitting layer 10 (or the third light emitting layer 30 when the third light emitting layer 30 is present) and the second light emitting layer 20. (Or the third light emitting layer 30 in the case where the third light emitting layer 30 is present) and the second light emitting layer 20 based on GaP or Al (In) GaP on the GaN-based first light emitting layer having a large lattice mismatch And serves to bond by wafer bonding. In order to reflect light incident from the first light emitting layer 10 and / or the third light emitting layer 30 having a larger bandgap of the multiple quantum wells into the second light emitting layer 20, the bonding layer may be formed of GaP or Al (In ) GaP and one or more oxide layers having different refractive indices. The construction of the bonding layer will be described later in detail.

4A to 4F are cross-sectional views showing respective steps of a method of manufacturing a color LED according to an embodiment.

4A, a first light emitting layer 10 is grown on the first substrate 100 in an epitaxial manner and a second light emitting layer 20 is grown on the second substrate 200 in an epitaxial manner . In one embodiment, a sacrificial layer 210 for etching is further formed between the second substrate 200 and the second light emitting layer 20.

The first substrate 100 is made of sapphire, and each layer of the first light emitting layer 10 may be made of a GaN-based material. The first light emitting layer 10 may include an n-type semiconductor layer 101, a first multiple quantum well layer 102 and a p-type semiconductor layer 103. By successively epitaxially growing these layers, (10) is formed. For example, the n-type semiconductor layer 101 is made of n-GaN, the first multiple quantum well layer 102 is made of InGaN and GaN, and the p-type semiconductor layer 103 is made of p-GaN However, the present invention is not limited thereto.

The second substrate 200 may be made of gallium arsenide (GaAs), and the sacrificial layer 210 may be made of aluminum gallium arsenide (AlGaAs). Each layer of the second light emitting layer 20 may be made of GaP or Al (In) GaP based material. The second light emitting layer 20 may include an n-type semiconductor layer 201, a second multiple quantum well layer 202 and a p-type semiconductor layer 203. By sequentially epitaxially growing these layers, (20) is formed. Type semiconductor layer 201 is made of n-Al (In) GaP, the second multiple quantum well layer 202 is made of Al (In) GaP, and the p-type semiconductor layer 203 is made of p -GaP, but is not limited thereto.

Referring to FIG. 4B, the bonding layers 104 and 204 may be formed on the first and second light emitting layers 10 and 20 prepared as described above. The bonding layers 104 and 204 are formed of at least one oxide layer having a different refractive index from that of GaP. The first and second light emitting layers 10 and 20 are bonded to each other, 2 light emitting layer 20 so as not to be absorbed. Although the bonding layers 104 and 204 are formed on the first luminescent layer 10 and the second luminescent layer 20 in the drawing, a bonding layer may be formed on only one of them.

In one embodiment, a conductive layer 110 is further formed between the first light emitting layer 10 and the bonding layer 104. The conductive layer 110 is for effective current spreading when the p-type semiconductor layer 103 is formed of a material having a relatively low conductivity and a relatively low conductivity such as p-GaN, and is formed of indium tin oxide ; ITO).

In one embodiment, the surfaces of the bonding layers 104 and 204 prepared as described above are subjected to chemical mechanical polishing (CMP). The polishing process is preferably performed while continuously supplying a polishing slurry by using a syringe, a squeeze bottle, or the like. In this case, the slurry may be mixed with deionized water (DI). Further, experiments were carried out by variously changing the rotation speed (unit: RPM) and the rotation time (unit: second (s)) of the substrate for polishing, and as a result, the processing conditions as shown in Table 1 were obtained.

Slurry stock solution 40 RPM
15s 40 RPM
30s 40 RPM
20s 40 RPM
15s 40 RPM
15s Slurry: DI (1: 1)
Squeeze bottle 40 RPM
15s 50 RPM
15s 30 RPM
30s 30 RPM
15s Slurry: DI (1: 1)
pipette 40 RPM
15s 40 RPM
30s

10A and 10B are photographs showing surface characteristics before and after surface polishing, respectively. 10A and 10B are measurement results of the polished surface using an atomic force microscope (AFM) using the process conditions of 40 RPM 30s among the process conditions shown in Table 1. [

10A is a photograph showing a state before the wafer is polished after about 300 nm thick yttria (Y ₂ O ₃ ) is formed as an oxide layer on gallium nitride (GaN), and FIG. 10B is a photograph showing the state of the yttrium oxide Y ₂ O ₃ ) is polished. 10A, the peak-to-peak distance is a maximum of 7 nm and the root mean square (RMS) of the peak is about 1.4 nm. On the other hand, the distance between peaks in the photograph of FIG. 10B after polishing is reduced to a maximum of 3 nm, The RMS of the silicon oxide film was also reduced to about 0.7 nm, and it was confirmed that the surface was modified by polishing.

Referring to FIG. 4C, the bonding layer 204 is bonded to the bonding layer 104 by wafer bonding in the state where the bonding layers 104 and 204 are formed as shown in FIG. 4B, (20) form a vertically stacked structure.

Next, as shown in FIG. 4D, the second substrate 200 and the sacrificial layer 210 are removed by etching.

Next, as shown in FIG. 4E, a part of the first light emitting layer 10 and the second light emitting layer 20 are removed by etching to pattern the pixel region.

On the other hand, in another embodiment, the wafer bonding of the bonding layer may be performed after the pixel region is predefined in the second light emitting layer 20. 5A to 5C are cross-sectional views showing some steps of a method of manufacturing a color LED according to another embodiment, and the process shown in Figs. 5A to 5C may be performed in place of the process shown in Figs. 4C to 4D.

Referring to FIG. 5A, in the state where the bonding layers 104 and 204 are formed on the first and second light emitting layers 10 and 20 as shown in FIG. 4B, The luminescent layer 20 and the bonding layer 204 on the second luminescent layer 20 can be patterned.

Next, the patterned bonding layer 204 and the second light emitting layer 20 can be wafer bonded onto the bonding layer 104 as shown in FIG. 5B.

Next, as shown in FIG. 5C, the second substrate 200 and the sacrificial layer 210 may be removed. This process can be performed by an epitaxial lift-off (ELO) method in which only the sacrifice layer 210 is selectively etched without affecting the second light-emitting layer 20. [ The etching of the sacrificial layer 210 by ELO can be performed using hydrogen fluoride (HF), hydrogen chloride (HCl), or the like as an etching solution.

Since the bonding layer 204 and the second light emitting layer 20 are already patterned in the state shown in FIG. 5C, the bonding layer 104 and the first light emitting layer 10 exposed in the region removed in the second light emitting layer 20 By defining the pixel region by patterning, the same structure as that shown in Fig. 4E of the above-described embodiment can be obtained.

4f, an electrode 40 electrically connected to the semiconductor layers on both sides of the multiple quantum well layer to apply electric power to each of the multiple quantum well layers of the first light emitting layer 10 and the second light emitting layer 20, Thereby completing the color LED. The region 401 corresponds to the light emitting device in which the first multiple quantum well layer 102 generates blue or green light and the region 402 corresponds to the light emitting device in which the second multiple quantum well layer 202 generates red light Emitting device.

Meanwhile, in the above-described embodiments, a method of manufacturing a color LED having two colors including two types of light emitting devices, i.e., the first light emitting layer 10 and the second light emitting layer 20 has been described. However, it is also possible to manufacture a color LED having three colors by further including a third light emitting layer as described below.

6A to 6F are cross-sectional views showing respective steps of a method of manufacturing a color LED according to another embodiment. In the description of the embodiment shown in Figs. 6A to 6F, the same or similar elements as those of the embodiment described above with reference to Figs. 4A to 4F will not be described in detail in order to avoid duplication of description.

6A, a first light emitting layer 10 is formed on a first substrate 100 in the same manner as described above with reference to FIG. 4A, a second light emitting layer 20 is formed on a second substrate 200, . Next, a third light emitting layer 30 is further formed on the first light emitting layer 10 by an epitaxial growth method.

The third light emitting layer 30 is made of a GaN-based material, similar to the first light emitting layer 10, for generating light of a different color from that of the first light emitting layer 10 due to the difference in the multiple quantum well structure. The third light emitting layer 10 may include a third multiple quantum well layer 301 and an n-type semiconductor layer 302 and may be sequentially formed on the p-type semiconductor layer 103 of the first light emitting layer 10 The third light emitting layer 30 is formed. For example, the third multiple quantum well layer 301 may be made of InGaN and GaN, and the n-type semiconductor layer 302 may be made of n-GaN, but the present invention is not limited thereto.

In this case, the p-type semiconductor layer 103 is commonly used by the first light emitting layer 10 and the third light emitting layer 30. However, this is an example, and the third light emitting layer 30 may be configured to include a p-type semiconductor layer separately from the first light emitting layer 10.

Next, the bonding layers 104 and 204 may be formed on the third light emitting layer 30 and / or the second light emitting layer 20 as shown in FIG. 6B. Further, a conductive layer 110 may be further formed between the third light emitting layer 30 and the bonding layer 104. The structures of the bonding layers 104 and 204 and the conductive layer 110 are the same as those described above with reference to FIG. 4B.

Next, the first luminescent layer 10, the third luminescent layer 30, and the second luminescent layer 20 are stacked vertically by wafer bonding the bonding layer 204 to the bonding layer 104 as shown in Fig. 6C Structure.

Next, as shown in FIG. 6D, the second substrate 200 and the sacrifice layer 210 are removed by etching.

Next, as shown in FIG. 6E, the pixel region is patterned by removing a portion of the first light emitting layer 10, the third light emitting layer 30, and the second light emitting layer 20 by etching.

With respect to the process shown in Figs. 6C to 6D, the wafer bonding of the bonding layer may be performed after the pixel region is predefined in the second light emitting layer 20 as described above with reference to Figs. 5A to 5C. 7A to 7C are cross-sectional views showing some steps of a method of manufacturing a color LED according to another embodiment, and the processes shown in Figs. 7A to 7C may be performed in place of the processes shown in Figs. 6C to 6D.

Referring to FIG. 7A, in a state where the bonding layers 104 and 204 are formed on the third light emitting layer 30 and / or the second light emitting layer 20 as shown in FIG. 6B, The bonding layer 204 on the light emitting layer 20 and the second light emitting layer 20 may be patterned and the patterned bonding layer 204 and the second light emitting layer 20 may be wafer bonded onto the bonding layer 104.

Next, as shown in FIG. 7B, the second substrate 200 and the sacrificial layer 210 may be removed. This process can be performed by the same ELO process as described above with reference to Fig. 5C.

Since the bonding layer 204 and the second light emitting layer 20 are already patterned in the state shown in FIG. 7B, the bonding layer 104, the third light emitting layer 30, and the third light emitting layer 20 exposed in the region removed in the second light emitting layer 20 By defining the pixel region by patterning the first light emitting layer 10, the same structure as that shown in Fig. 6E of the above-described embodiment can be obtained.

Referring to FIG. 6F, in order to apply electric power to each of the multiple quantum well layers of the first luminescent layer 10, the third luminescent layer 30 and the second luminescent layer 20, the semiconductor layers on both sides of the multiple quantum well layer are electrically The color LED is completed. The region 401 corresponds to a light emitting device in which the first multiple quantum well layer 102 generates blue light and the region 403 corresponds to the light emitting device in which the third multiple quantum well layer 301 emits green light. And the region 402 corresponds to the light emitting element in which the second multiple quantum well layer 202 generates red light.

The first light emitting layer 10 and the third light emitting layer 30 share the p-type semiconductor layer 103 so that the electrode 40 contacting the p-type semiconductor layer 103 is electrically connected to the first light emitting layer 10 ) And the third light emitting layer 30 are commonly used. However, in other embodiments, the first light emitting layer 10 and the third light emitting layer 30 may be configured to be in electrical contact with the two electrode lines for applying electric power, respectively, Respectively.

In the embodiment described above with reference to Figs. 6A to 7B, the third light emitting layer 30 was grown on the first light emitting layer 10 in an epitaxial growth manner. Accordingly, the first light emitting layer 10, the third light emitting layer 30, and the second light emitting layer 20 are successively transferred to the third light emitting layer 30 by the wafer bonding process of the second light emitting layer 20 A vertically stacked structure can be obtained. However, the third light emitting layer 30 may be grown on a separate substrate as well as the second light emitting layer 20, and then may be transferred onto the first light emitting layer 10 through wafer bonding.

8A to 8D are cross-sectional views showing some steps of a method of manufacturing a color LED according to another embodiment in which the third light emitting layer is bonded onto the first light emitting layer. In the description of the embodiment shown in Figs. 8A to 8D, the same or similar elements as those of the above-described embodiments with reference to Figs. 6A to 6F will be omitted in order to avoid duplication of description.

8A, a first light emitting layer 10 is grown on an epitaxial growth method on a first substrate 100 and a third light emitting layer 30 is epitaxially grown on a third substrate 300 Can grow.

The third substrate 300 may be made of sapphire, and each layer of the third light emitting layer 30 may be made of a GaN-based material. The third light emitting layer 30 may include an n-type semiconductor layer 302, a third multiple quantum well layer 301, and a p-type semiconductor layer 303. By sequentially epitaxially growing these layers, (30) is formed. For example, the n-type semiconductor layer 302 is made of n-GaN, the third multiple quantum well layer 301 is made of InGaN and GaN, and the p-type semiconductor layer 303 is made of p-GaN However, the present invention is not limited thereto.

Next, the bonding layers 114 and 304 may be formed on the first light emitting layer 10 and / or the third light emitting layer 30 as shown in FIG. 8B. The bonding layers 114 and 304 are formed of at least one oxide layer having a different refractive index from that of GaN. The first and second light emitting layers 10 and 30 are bonded to each other, 3 light-emitting layer 30 so as not to be absorbed. Although the bonding layers 114 and 304 are formed on the first luminescent layer 10 and the third luminescent layer 30 in the drawing, a bonding layer may be formed on only one of them.

A conductive layer 120 may be further formed between the first light emitting layer 10 and the bonding layer 114 or a conductive layer 310 may be formed between the third light emitting layer 30 and the bonding layer 304. [ ) Is further formed.

Next, the bonding layer 304 is wafer bonded onto the bonding layer 114 as shown in Fig. 8C. The first light emitting layer 10 and the third light emitting layer 30 may be vertically stacked.

Next, as shown in FIG. 8D, the third substrate 300 is removed by etching. The resultant structure is the same as the vertical lamination structure of the first light emitting layer 10 and the third light emitting layer 30 by the epitaxial growth shown in FIG. 6A except that the bonding layers 114 and 304 and the third light emitting layer 30 Type semiconductor layer 303 of the second conductivity type. The process shown in FIGS. 6B to 6F or FIGS. 7A and 7B may be performed in the same manner as the structure shown in FIG. 8D, and a detailed description thereof will be omitted.

The above-described embodiments are based on the assumption that two kinds of light emitting elements included in the color LEDs (Figs. 4A to 4F, Figs. 5A to 5C) or three types (Figs. 6A to 6F, 7A and 7B) (Figs. 4A to 4F, Figs. 6A to 6F), or the substrate is removed by ELO after the second light emitting layer is previously patterned (Figs. 5A to 5C, Figs. 7A and 7B) 3 emissive layer is epitaxially grown on the first light emitting layer (Figs. 4A to 7B) or bonded (Figs. 8A to 8D).

Meanwhile, in any of the above-described embodiments, the pixel region may be patterned in advance with respect to the GaN-based first light emitting layer 10 and / or the third light emitting layer 30, and then GaP or Al (In ) GaP-based second light emitting layer 20 may be wafer bonded. 9A to 9E illustrate a method of manufacturing a color LED in which GaN-based layers are pre-patterned in an embodiment in which three types of light emitting devices are used and a third light emitting layer and a first light emitting layer are bonded to each other Fig.

Referring to FIG. 9A, after the first luminescent layer 10 and the third luminescent layer 30 are vertically stacked as shown in FIG. 8D, the first luminescent layer 10, the bonding layers 114 and 304, The light emitting layer 303 may be patterned to define a pixel region and at least one electrode 40 may be formed for applying electric power to the multiple quantum well layers 102 and 301 of the light emitting layers 10 and 30.

Next, as shown in FIG. 9B, the bonding layer 124 may be formed so as to entirely cover the first light emitting layer 10 and the third light emitting layer 30 in which the pixel region is patterned and the electrode 40 in contact with the third light emitting layer 30 . The bonding layer 124 may have the same configuration as the bonding layer 104 shown in Figs. 4B and 6B. 4A and 6B, the bonding layer 204 may also be formed on the second light emitting layer 20 on the second substrate 200. [

Next, the bonding layer 204 may be wafer bonded onto the bonding layer 124 as shown in Fig. 9C. This is performed by the same process as wafer bonding of the bonding layers 104 and 204 shown in Figs. 4C and 6C.

Next, as shown in FIG. 9D, the second substrate 200 can be removed by etching. If the sacrificial layer 210 is present between the second substrate 200 and the second emission layer 20, the sacrificial layer 210 may also be removed.

Next, a pixel region is defined by etching the exposed second light emitting layer 20 as shown in FIG. 9E. As a result, the region 401 corresponds to the light emitting device in which the first multiple quantum well layer 102 generates blue light, and the region 403 corresponds to the light emitting device in which the third multiple quantum well layer 301 emits green light And the region 402 corresponds to the light emitting element in which the second multiple quantum well layer 202 generates red light.

9A to 9E, the second substrate 200 is removed by etching the bonding layers 124 and 204 after wafer bonding, and the second light emitting layer 20 is patterned. However, as shown in FIGS. 7A and 7B Similarly, after the second light emitting layer 20 is patterned in advance, the bonding layers 124 and 204 may be bonded and the second substrate 200 may be removed by ELO.

The color LED constructed in accordance with the embodiments described above has a structure in which two or three kinds of light emitting devices of different colors are stacked vertically on a substrate by at least one transfer process and light emitted from the light emitting devices Is output through the optically transparent first substrate 100, and the color implementation does not require a separate color filter or the like. In the LED according to the present embodiments, light is emitted in the direction of the light emitting device having a narrow band gap from the light emitting device having a narrow band gap in consideration of the band gap of each color light emitting device, There is no absorption loss problem.

11 is a graph showing band gap characteristics of a vertical stacked color LED according to an embodiment.

Referring to FIG. 11, since the first band gap 1110 of the first light emitting layer and the third band gap 1130 of the third light emitting layer are larger than the second band gap 1120 of the second light emitting layer, The generated red light is output without being absorbed by the first light-emitting layer and / or the third light-emitting layer. On the other hand, conversely, green and / or blue light may be incident on the second light emitting layer and absorbed. In order to reflect light incident on the second light emitting layer, the bonding layer for bonding the second light emitting layer is made of at least one oxide having a refractive index different from gallium phosphide (GaP). Further, the bonding layer may be composed of a plurality of oxide layers having different refractive indexes from each other.

(N = 1, 3, 5, etc., odd numbers), where λ is the wavelength of the light to be reflected (ie, blue or green light), and n is the index of refraction of the oxide layer And a pair of two different oxide layers having different thicknesses. Further, the bonding layer may include a plurality of such pairs of oxide layers. By using the bonding layer designed in this way, it is possible to realize a color LED of low power and high efficiency without light absorption loss occurring in the LED.

FIG. 12 is a graph illustrating the reflectance of each layer according to the structure of a junction layer in a vertical stacked color LED according to an exemplary embodiment. Referring to FIG.

The graph 1200 of FIG. 12 shows the reflectivity for each wavelength when the bonding layer is not used, and the graph 1210 shows the reflectance for each wavelength when a single layer of silicon oxide (SiO ₂ ) having a thickness of 78 nm is used as the bonding layer And the graph 1220 shows the reflection when silicon oxide (SiO ₂ ) with a thickness of 78 nm and a titanium oxide (TiO ₂ ) double layer with a thickness of 41 nm are used as a bonding layer. The silicon oxide (SiO ₂ ) and titanium oxide (TiO ₂ ) bilayers define a Distributed Bragg Reflector (DBR) and a titanium oxide (TiO ₂ ) layer is disposed adjacent to the second luminescent layer.

As shown in the figure, when the bonding layer is used, the reflectivity is increased. In particular, when the bonding layer is used as the double layer, the reflectivity increases greatly.

While the invention has been shown and described with reference to certain embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. However, it should be understood that such modifications are within the technical scope of the present invention. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

Claims (20)

Forming, on an optically transparent first substrate, a first light emitting layer comprising a first multiple quantum well layer having a first bandgap and a gallium nitride (GaN) based material in an epitaxial growth manner;
(GaP) or aluminum indium gallium phosphide (Al (In)) and a second quantum well layer having a second bandgap narrower than the first bandgap in an epitaxial growth manner on a second substrate, Forming a second light emitting layer made of GaP based material;
Bonding the second light emitting layer onto the first light emitting layer using a bonding layer including at least one oxide layer having a different refractive index from the second light emitting layer;
Patterning the second light emitting layer before or after the bonding step; And
And patterning the first light emitting layer bonded to the patterned second light emitting layer.
The method according to claim 1,
Wherein the step of patterning the second light emitting layer is performed after the step of bonding,
Further comprising the step of removing the second substrate located on the second light emitting layer by etching before the step of patterning the second light emitting layer after the bonding step.
The method according to claim 1,
Wherein forming the second light emitting layer includes forming a sacrificial layer between the second substrate and the second multiple quantum well layer,
Wherein the step of patterning the second light emitting layer is performed before the step of bonding,
Further comprising etching the sacrificial layer to remove the second substrate before patterning the first emissive layer after the bonding step.
The method according to claim 1,
Wherein the first multiple quantum well layer comprises indium gallium nitride and gallium nitride.
5. The method of claim 4,
Wherein the first substrate comprises sapphire.
The method according to claim 1,
And the second multiple quantum well layer comprises aluminum indium gallium phosphide.
The method according to claim 6,
Wherein the second substrate comprises gallium arsenide.
The method according to claim 1,
And a third multi quantum well layer having a third band gap narrower than the first band gap and wider than the second band gap on the first light emitting layer, Lt; RTI ID = 0.0 > of a < / RTI > material,
Wherein the second light emitting layer is bonded to the first light emitting layer through the third light emitting layer in the bonding step.
9. The method of claim 8,
Wherein the forming of the third light emitting layer includes forming the third light emitting layer on the second light emitting layer by an epitaxial growth method.
9. The method of claim 8,
The forming of the third light emitting layer may include:
Forming the third light emitting layer on a third substrate;
Bonding the third light emitting layer onto the first light emitting layer; And
And removing the third substrate with the third light emitting layer bonded to the first light emitting layer.
9. The method of claim 8,
And the third multiple quantum well layer comprises indium gallium nitride and gallium nitride.
The method according to claim 1,
Forming at least one electrode electrically contacting the patterned first light emitting layer or the patterned second light emitting layer.
An optically transparent substrate;
A first light emitting layer on the substrate, the first light emitting layer comprising a first multi quantum well layer having a first bandgap and made of a gallium nitride (GaN) based material;
And a second multiple quantum well layer having a second bandgap narrower than the first bandgap, the second multi quantum well layer being disposed on the first emission layer and being formed of gallium phosphide (GaP) or aluminum indium gallium phosphide (Al (In) GaP) A second light emitting layer made of a material of And
And a bonding layer disposed between the first light emitting layer and the second light emitting layer and including at least one oxide layer having a different refractive index from the second light emitting layer.
14. The method of claim 13,
Wherein the first multiple quantum well layer comprises indium gallium nitride and gallium nitride.
14. The method of claim 13,
And the second multi-quantum well layer comprises aluminum indium gallium phosphide.
14. The method of claim 13,
Wherein each of the first light emitting layer and the second light emitting layer further comprises one or more semiconductor layers located on one side of the first multiple quantum well layer or the second multiple quantum well layer.
14. The method of claim 13,
A third multi quantum well layer positioned between the first emitting layer and the second emitting layer and having a third bandgap narrower than the first bandgap and wider than the second bandgap, And a second light emitting layer formed on the first light emitting layer.
18. The method of claim 17,
And the third multi-quantum well layer comprises indium gallium nitride and gallium nitride.
14. The method of claim 13,
Further comprising at least one electrode electrically connected to the first light emitting layer or the second light emitting layer for applying electric power.
A semiconductor device comprising the vertical stacked color light emitting diode according to any one of claims 13 to 19.

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