KR20070092057A - Method for manufacturing white light emitting diode - Google Patents

Abstract

A method for fabricating a white light emitting device is provided to emit white light by bonding a fluorescent substrate to a light emitting structure including an active layer so that the light emitted from the light emitting structure is changed in wavelength in the fluorescent substrate and the wavelength-changed light is combined with the light emitted from the light emitting structure. A semiconductor layer(110) of a first polarity, an active layer(120) and a semiconductor layer(130) of an opposite polarity to the first polarity are sequentially stacked on an insulation substrate. The semiconductor layer of the second polarity is bonded to a fluorescent substrate(200). The insulation substrate is separated from the semiconductor layer of the first polarity. A first electrode(210) is formed on the semiconductor layer of the first polarity separated from the insulation substrate, and a second electrode(220) is formed on the fluorescent substrate. The insulation substrate can be a sapphire substrate. The active layer can be an active layer which emits blue light. The fluorescent substrate can be a fluorescent substrate having a yellow band.

Description

Method for manufacturing white light emitting diode

1 is a schematic cross-sectional view showing a state in which a yag (YAG) phosphor having a yellow band is applied to a blue light emitting diode according to the related art.

2A through 2C are cross-sectional views illustrating a process of manufacturing a white light emitting device according to a first embodiment of the present invention.

3 is a conceptual diagram illustrating a phenomenon in which white light is emitted from a white light emitting device according to a first embodiment of the present invention;

4A to 4C are cross-sectional views illustrating a process of manufacturing a white light emitting device according to a second embodiment of the present invention.

5A to 5D are cross-sectional views illustrating a process of manufacturing a white light emitting device according to a third embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

100 insulating substrate 110 semiconductor layer having a first polarity

120: active layer 130: semiconductor layer having a second polarity

150: conductive substrate 160: insulating transparent substrate

200: fluorescent substrate 210, 220: electrode

The present invention relates to a method of manufacturing a white light emitting device, and more particularly, by bonding a fluorescent substrate to a light emitting structure including an active layer, the light emitted from the light emitting structure is wavelength-converted in the fluorescent substrate, in the wavelength-converted light and the light emitting structure The present invention relates to a method of manufacturing a white light emitting device that can emit white light by combining light emitted.

Recently, in the field of light emitting diodes, considerable efforts have been made to develop blue light emitting devices and increase luminance using wide bandgap GaN based semiconductor semiconductors. We have also succeeded in implementing the device.

The light emitting diodes thus developed are used in various ways throughout the industry, thus creating a large market.

Blue and green are two of the three primary colors of light (red, green, and blue), which have been developed for a long time, and are not sufficient for commercialization using conventional compound semiconductors before the development of GaN-based materials. Many.

Proper use of these blue and green light emitting diodes with previously developed red light emitting diodes makes it possible to produce essentially all colors and white light in the visible region.

In addition to the method of realizing white light using the R / G / B light emitting diode, a YAG phosphor is applied to a high brightness blue light emitting diode, and yellow light from blue and phosphor is synthesized to produce a white light emitting diode. Implementation methods are also used.

The white light source using the light emitting diode has an important meaning because it is possible to realize eco-friendly lighting with small size, low power consumption and no environmental pollution.

Currently, active researches around the world are being conducted for use as a light source for a backlight unit (BLU) of a liquid crystal display, a light source for a projection TV and a projector.

In addition, although it may require a considerable amount of time, the possibility of using it as a general lighting alternative to fluorescent light is being discussed, and thus, a light source for a keypad, a light source for side emitting light, and a light emitting diode market formed in various fields are used. White light-emitting diodes are emerging as high value-added devices because they are expected to form a large market.

FIG. 1 is a schematic cross-sectional view showing a state in which a yag (YAG) phosphor having a yellow band is applied to a blue light emitting diode according to the related art, and a blue light emitting diode on a reflecting plate of the lid 10. 20 is bonded, and a yag phosphor 30 having a yellow band is wrapped around the blue light emitting diode 20.

Here, a part of the light emitted from the blue light emitting diode 20 is converted into yellow light in the yag phosphor, and the blue light of the blue light emitting diode 20 and the yellow light converted in the yag phosphor combine to emit white light. do.

That is, some of the 450 ~ 470nm blue light generated in the active layer of the blue light emitting diode 20 is emitted to the air without reacting with the phosphor, the remaining blue light is absorbed by the phosphor to lose energy, fit the yellow band It will emit a yellow glow.

The blue light that does not react with the phosphor and the yellow light generated by reacting with the phosphor are mixed with each other to be seen as white light.

Accordingly, the present invention bonds a fluorescent substrate to a light emitting structure including an active layer, and the light emitted from the light emitting structure is wavelength-converted in the fluorescent substrate, the wavelength-converted light and the light emitted from the light emitting structure are combined to emit white light It is an object to provide a method of manufacturing a light emitting device.

Another object of the present invention is to grow a light emitting structure including an active layer independently from a fluorescent substrate to excellent crystallinity, and to manufacture a white light emitting device that can improve the reliability of the device by integrating the light emitting structure and the fluorescent substrate in a simple bonding process To provide a way.

Preferred embodiments for achieving the above object of the present invention,

Sequentially stacking a semiconductor layer having a first polarity, an active layer, and a semiconductor layer having a second polarity opposite to the first polarity on the insulating substrate;

Bonding the semiconductor layer having the second polarity to a fluorescent substrate;

Leaving the insulating substrate away from the semiconductor layer having a first polarity;

A method of manufacturing a white light emitting device is provided, including forming a first electrode on a surface of a semiconductor layer having a first polarity from which the insulating substrate is separated, and forming a second electrode on the fluorescent substrate.

Another preferred aspect for achieving the above object of the present invention is

Sequentially stacking a semiconductor layer having a first polarity, an active layer, and a semiconductor layer having a second polarity opposite to the first polarity on the conductive substrate;

Bonding a fluorescent substrate over the semiconductor layer having the second polarity;

A method of manufacturing a white light emitting device is provided, including forming a first electrode under the conductive substrate and forming a second electrode on the fluorescent substrate.

Another preferred aspect for achieving the above object of the present invention,

Sequentially stacking a semiconductor layer having a first polarity, an active layer, and a semiconductor layer having a second polarity opposite to the first polarity on the insulating transparent substrate;

Mesa etching a portion of the semiconductor layer having the first polarity from the semiconductor layer having the second polarity;

Bonding a fluorescent substrate under the semiconductor layer having the first polarity;

A method of manufacturing a white light emitting device is provided, comprising: forming a first electrode on an upper surface of a semiconductor layer having a mesa etched first polarity, and forming a second electrode on the upper surface of the semiconductor layer having a second polarity.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

2A through 2C are cross-sectional views illustrating a process of manufacturing a white light emitting device according to a first embodiment of the present invention. First, a semiconductor layer 110, an active layer 120, and the first layer having a first polarity are disposed on an insulating substrate 100. The semiconductor layers 130 having the second polarity opposite to the first polarity are sequentially stacked (FIG. 2A).

Here, the insulating substrate 100 is preferably a sapphire substrate, and the semiconductor layers 110 and 130 are GaN-based semiconductor layers.

In addition, the active layer 120 is an active layer emitting a blue wavelength of 450 ~ 470nm AlInGaN.

In addition, the semiconductor layer 110 having the first polarity is an N-type semiconductor layer, and the semiconductor layer 130 having the second polarity is a P-type semiconductor layer.

Next, the semiconductor layer 130 having the second polarity is bonded to the fluorescent substrate 200 (FIG. 2B).

In this case, the active layer 120 is formed of an active layer emitting blue light, and the fluorescent substrate 200 is preferably a fluorescent substrate having a yellow band.

In particular, the fluorescent substrate is preferably a ZnSe substrate or ZnTe substrate.

In this case, the bonding between the semiconductor layer 130 having the second polarity and the fluorescent substrate 200 is preferably fusion bonding.

Subsequently, the insulating substrate 100 is separated from the semiconductor layer 110 having the first polarity (FIG. 2C).

At this time, the separation of the insulating substrate 100 from the semiconductor layer 110 having the first polarity is performed by performing a laser lift-off process of leaving the insulating substrate 100 by irradiating laser light. It is preferable.

Finally, the first electrode 210 is formed on the surface of the semiconductor layer 110 having the first polarity from which the insulating substrate 100 is separated, and the second electrode 220 is formed on the fluorescent substrate 200. (FIG. 2D)

Therefore, according to the first embodiment of the present invention, a light emitting device structure is grown on an insulator substrate having a smooth growth of a light emitting device structure including an active layer, the insulator substrate is removed, and electrodes are formed in the removed region and the fluorescent substrate, respectively. It is to manufacture a vertical white light emitting device.

3 is a conceptual view illustrating a phenomenon in which white light is emitted from a white light emitting device according to the first embodiment of the present invention. The white light emitting device manufactured by performing the processes of FIGS. 2A to 2D has an active layer 120. If the fluorescent layer 200 emits blue light, and the fluorescent substrate 200 is a fluorescent substrate having a yellow band, the light traveling to the fluorescent substrate 200 among the blue light emitted from the active layer 120 is It is absorbed by the fluorescent substrate 200 to lose energy and is converted to yellow light and emitted.

The yellow light emitted from the fluorescent substrate 200 ('B' light in FIG. 3) is combined with the blue light emitted from the active layer 120 to become white light.

Therefore, the white light emitting device of the present invention emits white light.

4A to 4C are cross-sectional views illustrating a process of manufacturing a white light emitting device according to a second exemplary embodiment of the present invention, wherein the semiconductor layer 110, the active layer 120, and the first polarity have a first polarity on the conductive substrate 150. The semiconductor layers 130 having the second polarity opposite to the semiconductor layers 130 are sequentially stacked (FIG. 4A).

Here, the conductive substrate 150 is a GaN-based semiconductor layer.

Thereafter, the fluorescent substrate 200 is bonded onto the semiconductor layer 130 having the second polarity (FIG. 4B).

Finally, the first electrode 210 is formed below the conductive substrate 150, and the second electrode 220 is formed on the fluorescent substrate 200 (FIG. 4C).

As described above, according to the second embodiment of the present invention, a vertical white light emitting device is formed by growing a light emitting device structure including an active layer on a conductive substrate and forming electrodes on the conductive substrate and the fluorescent substrate, respectively, without removing the conductive substrate. To manufacture.

5A through 5D are cross-sectional views illustrating a process of manufacturing a white light emitting device according to a third exemplary embodiment of the present invention, wherein the semiconductor layer 110, the active layer 120, and the first layer have a first polarity on an insulating transparent substrate 160. The semiconductor layers 130 having the second polarity opposite to the polarities are sequentially stacked (FIG. 5A).

Here, the insulating transparent substrate 160 is preferably a sapphire substrate.

Subsequently, Mesa is etched from the semiconductor layer 130 having the second polarity to a part of the semiconductor layer 110 having the first polarity (FIG. 5B).

Subsequently, the fluorescent substrate 200 is bonded to the lower portion of the semiconductor layer 110 having the first polarity (FIG. 5C).

Finally, the first electrode 210 is formed on the semiconductor layer 110 having the mesa-etched first polarity, and the second electrode 220 is formed on the semiconductor layer 130 having the second polarity. (FIG. 5D)

In a third embodiment of the present invention, a light emitting device structure including an active layer is grown on an insulating transparent substrate, a mesa etched, and an electrode is formed on each of the mesa etched semiconductor layer and the uppermost semiconductor layer to manufacture a horizontal white light emitting device. It is.

Here, the light is absorbed by the fluorescent substrate through the insulating transparent substrate, and the wavelength-converted light emitted from the fluorescent substrate is emitted to the upper portion of the device through the insulating transparent substrate.

As described above, in the first to third embodiments of the present invention, the light emitting structure including the active layer is grown independently of the fluorescent substrate so that the crystallinity is excellent, and the light emitting structure and the fluorescent substrate are integrated in a simple bonding process to ensure the reliability of the device. There is an advantage to improve.

As described above in detail, the present invention bonds a fluorescent substrate to a light emitting structure including an active layer, the light emitted from the light emitting structure is wavelength-converted in the fluorescent substrate, the wavelength-converted light and the light emitted from the light emitting structure is combined to white light There is an effect that can emit.

In addition, the present invention has the effect of growing the light emitting structure including the active layer independently from the fluorescent substrate to excellent crystallinity, and improve the reliability of the device by integrating the light emitting structure and the fluorescent substrate in a simple bonding process.

Although the invention has been described in detail only with respect to specific examples, it will be apparent to those skilled in the art that various modifications and variations are possible within the spirit of the invention, and such modifications and variations belong to the appended claims.

Claims (9)

Sequentially stacking a semiconductor layer having a first polarity, an active layer, and a semiconductor layer having a second polarity opposite to the first polarity on the insulating substrate; Bonding the semiconductor layer having the second polarity to a fluorescent substrate; Leaving the insulating substrate away from the semiconductor layer having a first polarity; And forming a first electrode on the surface of the semiconductor layer having a first polarity from which the insulating substrate is separated, and forming a second electrode on the fluorescent substrate. The method of claim 1, The insulating substrate, It is a sapphire substrate, The manufacturing method of the white light emitting element characterized by the above-mentioned. The method of claim 1, The step of detaching the insulating substrate from the semiconductor layer having a first polarity, A method of manufacturing a white light emitting device, characterized in that to perform a laser lift-off process of leaving a substrate for irradiating laser light. Sequentially stacking a semiconductor layer having a first polarity, an active layer, and a semiconductor layer having a second polarity opposite to the first polarity on the conductive substrate; Bonding a fluorescent substrate over the semiconductor layer having the second polarity; Forming a first electrode under the conductive substrate and forming a second electrode on the fluorescent substrate. Sequentially stacking a semiconductor layer having a first polarity, an active layer, and a semiconductor layer having a second polarity opposite to the first polarity on the insulating transparent substrate; Mesa etching from the semiconductor layer having the second polarity to a part of the semiconductor layer having the first polarity; Bonding a fluorescent substrate under the semiconductor layer having the first polarity; And forming a first electrode on the semiconductor layer having the mesa etched first polarity and forming a second electrode on the semiconductor layer having the second polarity. The method according to any one of claims 1 to 5, The active layer, An active layer that emits blue light, The fluorescent substrate, A method of manufacturing a white light emitting device, characterized in that it is a fluorescent substrate having a yellow band. The method of claim 6, The fluorescent substrate, It is a ZnSe substrate or a ZnTe substrate, The manufacturing method of the white light emitting element characterized by the above-mentioned. The method according to any one of claims 1 to 5, The fluorescent substrate, A white light emitting device manufacturing method characterized in that the bonding by fusion bonding (Fusion bonding). The method according to any one of claims 1 to 5, The semiconductor layer having the first polarity, N type semiconductor layer, The semiconductor layer having the second polarity, It is a P type semiconductor layer, The manufacturing method of the white light emitting element characterized by the above-mentioned.

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