KR100823089B1 - Method of fabricating light emitting diode having wavelength converting layer - Google Patents

Abstract

A method for manufacturing a light emitting diode having a wavelength converting layer is provided to prevent the wavelength converting layer from being formed on pad electrode by using a mask. A first conductive type lower semiconductor layer(25), an active layer(27) and a second conductive type upper semiconductor layer(29) are formed on a substrate(21). The semiconductor layers are patterned to define light emitting diode regions. A first pad electrode(35) and a second pad electrode(33) are formed on the exposed the first conductive type lower semiconductor layer and the second conductive type upper semiconductor layer. A mask having mask patterns and through-holes are prepared, and then metal patterns(53) are formed on the mask patterns. The mask is attached to the pad electrodes, and the metal patterns are bonded to the pad electrodes. A wavelength converting layer(37) is applied on the light emitting diode layers through the through-holes, and then is cured.

Description

METHODS OF FABRICATING LIGHT EMITTING DIODE HAVING WAVELENGTH CONVERTING LAYER

1 to 6 are cross-sectional views illustrating a method of manufacturing a light emitting diode having a wavelength conversion material layer according to an embodiment of the present invention.

7 to 9 are cross-sectional views illustrating a method of manufacturing a light emitting diode having a wavelength conversion material layer according to another embodiment of the present invention.

The present invention relates to a light emitting diode manufacturing method, and more particularly to a light emitting diode manufacturing method having a wavelength conversion material layer at the chip level.

In general, the white light emitting device is a part of the light emitted from the gallium nitride (GaN) series, particularly aluminum-indium-gallium nitride (Al _x In _y Ga _z N) series light emitting diodes and light emitting diodes that emit ultraviolet light or blue light It includes a phosphor that absorbs and emits light of a long wavelength. Since the white light emitting device uses a single wavelength light source as a light source, the structure of the white light emitting device is very simple and inexpensive compared to the white light emitting device using light sources of various wavelengths.

stel et al.)에 의해 개시된 바 있다. 한편, 청색 발광 다이오드를 채택한 백색 발광소자가 미국특허 제6,252,254호에 "형광체 조성물을 구비한 발광 소자"(Light emitting device with phosphor composition)라는 제목으로 소울즈 등(Soules et al.)에 의해 개시된 바 있다. 상기 미국특허들에 따르면, 약 90 정도의 상당히 높은 연색평가수(color rendering index; CRI) 및 높은 광효율을 나타내는 백색 발광소자를 제공할 수 있다. A white light emitting device employing an ultraviolet light emitting diode is known as "White light emitting diode" in US Pat. No. 6,084,250.

stel et al.). Meanwhile, a white light emitting device employing a blue light emitting diode has been disclosed by Soules et al. In US Pat. No. 6,252,254 entitled “Light emitting device with phosphor composition”. . According to the above-mentioned US patents, it is possible to provide a white light emitting device exhibiting a considerably high color rendering index (CRI) of about 90 and high light efficiency.

The conventional white light emitting device realizes white light at the package level. That is, white light is realized by covering a light emitting diode chip emitting monochromatic light with a layer of a wavelength conversion material such as an epoxy resin containing a phosphor. Therefore, in the conventional white light emitting device, since the wavelength conversion material layer containing the phosphor is formed in the packaging process separately from the manufacturing process of the light emitting diode, the packaging process of the light emitting diode is complicated, which leads to a high defect rate of the packaging process. The failure of the packaging process results in a significant cost loss compared to the failure of the light emitting diode manufacturing process.

Meanwhile, in order to solve the above problems, a method of manufacturing a light emitting diode having a wavelength conversion material layer at a chip level has been studied. This method can simplify the light emitting diode packaging process by forming the wavelength converting material layer at the wafer level, and can reduce the cost loss by reducing the defective rate of the packaging process. However, when the wavelength conversion material layer is formed at the wafer level, the wavelength conversion material layer may be formed on the pad electrodes. Since the wavelength converting material layer is insulating, the wavelength converting material layer formed on the pad electrodes interferes with the electrical connection between the external power source and the pad electrodes.

In addition, when an inorganic phosphor is mixed with a liquid resin such as an epoxy resin and a wavelength conversion material layer covering the light emitting diode chip is formed using the same, a phenomenon in which the phosphor precipitates due to the difference in specific gravity between the phosphor and the epoxy resin occurs. easy to do. When the phosphor precipitates, the phosphor is not uniformly distributed in the wavelength conversion material layer, and the phosphor comes into contact with the light emitting diode. As a result, the light emitting element hardly exhibits uniform brightness, and the phosphor is easily deformed by the light of the light emitting diode.

An object of the present invention is to provide a method of manufacturing a light emitting diode having a wavelength conversion material layer at the chip level.

Another object of the present invention is to provide a light emitting diode manufacturing method capable of preventing the formation of a wavelength conversion material layer on pad electrodes for electrically connecting a light emitting diode to an external power source.

Another object of the present invention is to provide a light emitting diode manufacturing method which can prevent the phosphor from depositing and contacting the light emitting diode.

In order to achieve the above technical problem, the present invention provides a light emitting diode manufacturing method having a wavelength conversion material layer. The method includes forming a first conductivity type lower semiconductor layer, an active layer and a second conductivity type upper semiconductor layer on the substrate. The semiconductor layers may be patterned to define light emitting diode regions in which one region of the first conductivity type lower semiconductor layer is exposed. Thereafter, a first pad electrode and a second pad electrode are formed on the exposed first conductive lower semiconductor layer and the second conductive upper semiconductor layer of each light emitting diode region. Meanwhile, a mask having mask patterns and through holes corresponding to the pad electrodes is prepared, and the mask is attached to the pad electrodes so that the mask patterns of the mask cover the pad electrodes. Thereafter, a wavelength conversion material layer is applied and cured on the light emitting diode regions through the through holes of the mask. Thereafter, the mask is separated from the pad electrodes. Accordingly, the wavelength conversion material layer containing the phosphor may be selectively formed on the light emitting diode regions except for the upper part of the pad electrodes, so that the light emitting diode having the wavelength conversion material layer at the chip level may be manufactured. It is possible to prevent the formation of the wavelength conversion material layer on the electrodes.

Preferably, the first pad electrodes and the second pad electrodes are formed to have the same height with respect to an upper surface of the second conductive upper semiconductor layer.

Meanwhile, before forming the second pad electrodes, a transparent electrode may be formed on the second conductive upper semiconductor layer.

Preparing the mask may further include forming metal patterns on the mask patterns. The mask is attached to the pad electrodes by bonding metal patterns on the mask patterns to the pad electrodes. Such bonding may be performed by metal melt bonding. In this case, the mask may be separated from the pad electrodes by separating the mask from the metal patterns. That is, after the mask is separated, the metal patterns remain on the pad electrodes.

Meanwhile, an oxide film may be first formed on the mask patterns before forming the metal patterns. The oxide film helps to separate metal patterns from the mask. In other words, the mask may be easily separated from the pad electrodes by separating the oxide layer from the metal patterns.

In some embodiments of the present disclosure, before attaching the mask to the pad electrodes, a photoresist pattern may be formed on the pad electrodes, and the mask may be formed on the pad electrodes by using the photoresist pattern. Can be attached. In this case, forming metal patterns on the mask patterns may be omitted. The mask can be easily separated from the pad electrodes by dissolving the photoresist pattern.

Meanwhile, before curing the wavelength converting material layer, the mask and the semiconductor layers may be rotated such that the mask faces downward and the semiconductor layers face upward. This prevents the phosphors from depositing toward the mask and preventing the phosphors from contacting the semiconductor layers.

The wavelength conversion material layer may be an SOG layer containing a phosphor. In addition, the wavelength conversion material layer may be an epoxy or silicone resin containing a phosphor.

Hereinafter, with reference to the accompanying drawings will be described embodiments of the present invention; The following embodiments are provided as examples in order to ensure that features of the present invention to those skilled in the art will fully convey. Accordingly, the invention is not limited to the embodiments described below and may be embodied in other forms. In the drawings, widths, lengths, thicknesses, and the like of components may be exaggerated for convenience. Like numbers refer to like elements throughout.

1 to 6 are cross-sectional views illustrating a method of manufacturing a light emitting diode having a wavelength conversion material layer according to an embodiment of the present invention.

Referring to FIG. 1, a first conductive lower semiconductor layer 25, an active layer 27, and a second conductive upper semiconductor layer 29 are formed on a substrate 21. In addition, the buffer layer 23 may be formed on the substrate 21 before the first conductivity type lower semiconductor layer 25 is formed.

The substrate 21 may include sapphire (Al ₂ O ₃ ), silicon carbide (SiC), zinc oxide (ZnO), silicon (Si), gallium arsenide (GaAs), gallium phosphorus (GaP), and lithium-alumina (LiAl ₂ O). ₃₎ , a boron nitride (BN), aluminum nitride (AlN) or gallium nitride (GaN) substrate, and may be appropriately selected depending on the material of the semiconductor layer to be formed on the substrate 21. For example, when forming a gallium nitride based semiconductor layer, a sapphire or silicon carbide (SiC) substrate may be selected as the substrate 21.

The buffer layer 23 is formed to mitigate lattice mismatch between the substrate 21 and the semiconductor layer 25 to be formed thereon, and may be formed of, for example, gallium nitride (GaN) or aluminum nitride (AlN).

The first conductive lower semiconductor layer 25, the active layer 27, and the second conductive upper semiconductor layer 29 may be formed of a gallium nitride based semiconductor material, that is, (B, Al, In, Ga) N, respectively. have. The active layer 27 has a composition element and a composition ratio determined so as to emit light having a desired wavelength, and the first conductive semiconductor layer 25 and the second conductive semiconductor layer 29 have a band compared to the active layer 27. The gap is formed of a large material. The first and second conductivity type semiconductor layers 25 and 29 and the active layer 27 may include metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy, or hydride vapor phase epitaxy (HVPE). The technique can be used to grow intermittently or continuously.

Here, the first conductivity type and the second conductivity type may be n type and p type, or p type and n type, respectively. In the gallium nitride-based compound semiconductor layer, the n-type semiconductor layer may be formed by doping silicon (Si) as an impurity, and the p-type semiconductor layer may be formed by doping magnesium (Mg) as an impurity.

Referring to FIG. 2, the second conductive upper semiconductor layer 29, the active layer 27, and the first conductive lower semiconductor layer 25 are patterned to define light emitting diode regions. In this case, the buffer layer 23 may also be patterned together. The upper and lower semiconductor layers 25 and 29 and the active layer 27 may be patterned using photolithography and etching processes.

The second conductive upper semiconductor layer 29 and the active layer 27 are patterned to be positioned on a portion of the patterned first conductive lower semiconductor layer 25, as shown. Accordingly, one region of the first conductivity type lower semiconductor layer 25 is exposed in each of the light emitting diode regions.

Referring to FIG. 3, a transparent electrode 31 is formed on the second conductive upper semiconductor layer 29. The transparent electrode 31 can be formed using a lift-off technique. The transparent electrode 31 is not particularly limited as long as it is an electrode material capable of transmitting light emitted from the active layer 27, and may be formed of, for example, Ni / Au or indium tin oxide (ITO).

In addition, a second pad electrode 33 is formed on a portion of the transparent electrode 31. The second pad electrode 33 can also be formed using a lift-off technique. Meanwhile, before forming the second pad electrode 33, the transparent electrode 31 may be patterned to form an opening that exposes the second conductive upper semiconductor layer 29. Thereafter, a second pad electrode 33 may be formed in the opening and the periphery thereof. As a result, as shown in the drawing, the second pad electrode 33 is in contact with the second conductive upper semiconductor layer 29 through the opening.

Meanwhile, the first pad electrode 35 is formed on another region of the first conductivity type lower semiconductor layer 25. The first pad electrode 35 may also be formed using a lift off technique. The first pad electrode 35 and / or the second pad electrode 33 may be formed of Ti / Au. The first pad electrode 35 may be formed to have substantially the same height as the second pad electrode 33 with respect to the upper surface of the second conductive upper semiconductor layer 29.

Referring to FIG. 4, a mask 51 having mask patterns 51a and through holes 51h is prepared. The mask is not particularly limited and may be prepared using, for example, stainless steel.

The mask patterns 51a may be disposed to correspond to the pad electrodes 33 and 35 disposed on the substrate 21, and may be disposed, for example, in a line pattern or a net pattern. The pad electrodes 33 and 35 may be formed to have a wider width, but are not limited thereto. The pad electrodes 33 and 35 may have a narrower width than the pad electrodes. However, the mask patterns 51a are formed to have a width necessary for bonding wires to the pad electrodes. On the other hand, the mask 51 preferably has through holes 51h between the mask patterns 51a, and the through holes 51h are regularly arranged.

Metal patterns 53 are formed on the mask patterns 51a. The metal patterns 53 may be formed through a patterning process after selective deposition or full surface deposition.

In addition, an oxide film (not shown) may be formed on the mask before the metal patterns 53 are formed. Thereafter, the metal patterns 53 may be formed on the oxide layer.

The metal patterns 53 are bonded to corresponding pad electrodes 33 and 35, respectively. The metal patterns 53 may be melt bonded to the pad electrodes 33 and 35.

In the present embodiment, the metal patterns 53 are formed on the mask patterns 51a, but the process of forming the metal patterns 53 may be omitted. In this case, mask patterns 51a are directly attached to the pad electrodes 33 and 35.

Referring to FIG. 5, a material containing a phosphor is injected through the through holes 51h to apply a wavelength conversion material layer 37 covering the light emitting diode regions. The wavelength conversion material layer 37 may be a spin-on-glass (SOG) or epoxy or silicon (silocone) resin containing a phosphor.

The wavelength conversion material layer 37 covers the light emitting diode regions except for upper portions of the pad electrodes 33 and 35. The wavelength conversion material layer 37 may fill the through holes 51h, but may be applied to fill under the mask 51, as shown.

Subsequently, the wavelength conversion material layer 37 is cured at a temperature of about 200 ° C. or less. Before curing the wavelength conversion material layer 37, the substrate 21 and the mask 51 may be integrally rotated such that the substrate 21 goes upward and the mask 51 goes downward. Accordingly, the phosphors in the wavelength converting material layer 37 will precipitate toward the mask 51, thereby preventing the phosphors in the wavelength converting material layer 37 after curing from contacting the semiconductor layers 25, 27 and 29. Can be.

Referring to FIG. 6, after the wavelength converting material layer 37 is cured, the mask 51 is separated from the pad electrodes 33 and 35. In this case, the metal patterns 35 may remain on the pad electrodes 33 and 35. That is, since the metal patterns 35 are separated from the mask patterns 51a, the mask 51 may be separated from the pad electrodes 33 and 35.

Thereafter, the light emitting diodes are separated by individual chip units. In this case, the light emitting diode regions may be separated by individual chip units to complete a single light emitting diode, but the present invention is not limited thereto, and the light emitting diode regions may be separated to be included in one chip. The plurality of light emitting diodes included in one chip may be connected in series with each other, and an AC type light emitting diode driven by an AC power source may be provided by connecting at least two series arrays in parallel.

According to the present exemplary embodiment, the wavelength conversion material layer 37 is formed on the pad electrodes 33 and 35 by using the mask patterns 51a or the metal patterns 35 corresponding to the pad electrodes 33 and 35. A light emitting diode having the wavelength converting material layer 37 can be manufactured while preventing this from being formed.

On the other hand, the wavelength conversion material layer 37 contains a phosphor for converting the wavelength of the light emitted from the active layer 27 to the light of the required wavelength, the light emitting diode capable of realizing light of a desired color, for example, white light at the chip level Can be prepared.

7 to 9 are cross-sectional views illustrating a method of manufacturing a light emitting diode having a wavelength conversion material layer according to another embodiment of the present invention.

Referring to FIG. 7, first, as described with reference to FIGS. 1 to 3, light emitting diode regions in which one regions of the first conductivity type lower semiconductor layer 25 are exposed on the substrate 21 are defined. Pad electrodes 33 and 35 are formed on the first conductive lower semiconductor layer 25 and the second conductive upper semiconductor layer 29.

Thereafter, photoresist patterns 65 are formed on the pad electrodes 33 and 35. The photoresist patterns 65 may be formed by applying a photoresist on the entire surface of the substrate on which the pad electrodes 33 and 35 are formed, and patterning the photoresist using a photographic and developing process. The photoresist remains on the pad electrodes 33 and 35 and is removed in the other light emitting diode regions to form the photoresist patterns 65.

Referring to FIG. 8, as described with reference to FIG. 4, a mask 71 having mask patterns 71a and through holes 71h is prepared, and the mask patterns 71a are formed on the pad electrodes. The pad electrodes 33 and 35 are attached to the pad electrodes 33 through the photoresist pattern 65 formed on the 33 and 35.

Here, since the photoresist patterns 65 serve as an adhesive, the process of forming the metal patterns 53 of FIG. 4 on the mask patterns 71a may be omitted.

Subsequently, as described with reference to FIG. 5, the wavelength conversion material layer 37 is applied by injecting a material containing a fluorescent agent through the through holes 71h. The wavelength conversion material layer 37 may be formed to fill the through holes 71h, but may be formed to expose side surfaces of the photoresist patterns 65 as shown. Subsequently, as described with reference to FIG. 5, the wavelength conversion material layer 37 is cured.

9, after the wavelength conversion material layer 37 is cured, the mask 71 and the photoresist patterns 65 are removed. The mask 71 may be separated first, and then the exposed photoresist patterns 65 may be removed using an organic solvent or the like. In addition, when the side surfaces of the photoresist pattern 65 are exposed, the mask 71 may be separated by dissolving the photoresist patterns 65 using an organic solvent or the like while the mask 71 is attached.

Thereafter, the light emitting diodes are separated by individual chip units. In this case, the light emitting diode regions may be separated by individual chip units, but is not limited thereto, and a plurality of light emitting diodes may be separated to be included in one chip to provide an AC light emitting diode.

According to the present exemplary embodiment, the process of forming the metal patterns (53 of FIG. 4) on the mask 71 may be omitted, thereby simplifying the process of preparing the mask.

According to the present embodiments, a light emitting diode having a wavelength converting material layer can be manufactured at the chip level, so that the process of forming the wavelength converting material layer in the packaging process can be omitted, thus reducing the defect rate of the packaging process. have. In addition, it is possible to prevent the formation of the wavelength conversion material layer on the pad electrodes by using the mask, and to prevent the phosphor in the wavelength conversion material layer from contacting the semiconductor layers.

Claims (11)

Forming a first conductivity type lower semiconductor layer, an active layer and a second conductivity type upper semiconductor layer on the substrate, Patterning the semiconductor layers to define light emitting diode regions in which one region of the first conductivity type lower semiconductor layer is exposed; Forming a first pad electrode and a second pad electrode on the exposed first conductive lower semiconductor layer and the second conductive upper semiconductor layer of each light emitting diode region; Preparing a mask having mask patterns and through holes corresponding to the pad electrodes, wherein metal patterns are formed on the mask patterns; Attaching the mask to the pad electrodes so that the mask patterns of the mask cover the pad electrodes, the metal patterns being bonded to the pad electrodes, Applying a wavelength conversion material layer on the light emitting diode regions through the through holes of the mask, Curing the applied wavelength converting material layer, And separating the mask from the pad electrodes. The method according to claim 1, The first and second pad electrodes are formed to have the same height with respect to the upper surface of the second conductive upper semiconductor layer. The method according to claim 1, And forming transparent electrodes on the second conductive upper semiconductor layers before forming the second pad electrodes. The method according to claim 1, The wavelength conversion material layer is a light emitting diode manufacturing method, characterized in that the epoxy or silicone resin containing a phosphor. The method according to claim 1, Separating the mask is performed by separating the mask from the metal patterns. The method according to claim 5, Preparing the mask further includes forming an oxide film on the mask patterns before forming the metal patterns, Separating the mask is performed by separating the oxide film from the metal patterns. Forming a first conductivity type lower semiconductor layer, an active layer and a second conductivity type upper semiconductor layer on the substrate, Patterning the semiconductor layers to define light emitting diode regions in which one region of the first conductive lower semiconductor layer is exposed; Forming a first pad electrode and a second pad electrode on the exposed first conductive lower semiconductor layer and the second conductive upper semiconductor layer of each light emitting diode region; Forming a photoresist pattern defined on the pad electrodes; Preparing a mask having mask patterns and through holes corresponding to the pad electrodes, Attaching the mask to the pad electrodes using the photoresist pattern such that the mask patterns of the mask cover the pad electrodes, Applying a wavelength conversion material layer on the light emitting diode regions through the through holes of the mask, Curing the applied wavelength converting material layer, And separating the mask from the pad electrodes. The method according to claim 7, And the mask is separated by dissolving the photoresist pattern. Forming a first conductivity type lower semiconductor layer, an active layer and a second conductivity type upper semiconductor layer on the substrate, Patterning the semiconductor layers to define light emitting diode regions in which one region of the first conductive lower semiconductor layer is exposed; Forming a first pad electrode and a second pad electrode on the exposed first conductive lower semiconductor layer and the second conductive upper semiconductor layer of each light emitting diode region; Preparing a mask having mask patterns and through holes corresponding to the pad electrodes, Attaching the mask to the pad electrodes so that the mask patterns of the mask cover the pad electrodes, Applying a wavelength conversion material layer on the light emitting diode regions through the through holes of the mask, Rotate the mask and the semiconductor layers so that the mask faces down and the semiconductor layers face upward, Curing the applied wavelength converting material layer, And separating the mask from the pad electrodes. Forming a first conductivity type lower semiconductor layer, an active layer and a second conductivity type upper semiconductor layer on the substrate, Patterning the semiconductor layers to define light emitting diode regions in which one region of the first conductive lower semiconductor layer is exposed; Forming a first pad electrode and a second pad electrode on the exposed first conductive lower semiconductor layer and the second conductive upper semiconductor layer of each light emitting diode region; Preparing a mask having mask patterns and through holes corresponding to the pad electrodes, Attaching the mask to the pad electrodes so that the mask patterns of the mask cover the pad electrodes, Applying a wavelength conversion material layer on the light emitting diode areas through the through holes of the mask, the wavelength conversion material layer is an SOG layer containing a phosphor, Curing the applied wavelength converting material layer, And separating the mask from the pad electrodes. delete

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