KR20100122770A - Method of manufacturing nitride-based semiconductor light emitting device - Google Patents

Abstract

PURPOSE: A method for manufacturing a nitride semiconductor light emitting device is provided to improve light extraction efficiency by forming a fine pattern on a light output surface through the irradiation of a laser beam. CONSTITUTION: A nitride semiconductor light emitting device comprises a first electrode(370) on a first conductive nitride layer(320) exposed by a mesa etching and a second electrode(360) formed on a transparent electrode(350). The first conductive nitride layer exposed by the mesa etching has a fine pattern for light extraction on a region except the first electrode. A substrate(310) has high heat conductivity and supports a light emitting structure.

Description

Method of manufacturing nitride-based semiconductor light emitting device

The present invention relates to a method for manufacturing a nitride-based semiconductor light emitting device, and more particularly, it is possible to form a fine pattern for light extraction on the light emitting surface through a simple manufacturing process, thereby the nitride-based semiconductor with improved light extraction efficiency The manufacturing method of a light emitting element.

In recent years, nitride-based semiconductor light emitting devices are light emitting devices capable of generating light in a wide wavelength band including short wavelength light such as blue or green, and white light emitting diodes have also been commercialized, and the market is rapidly growing. With the emergence of high efficiency three primary colors and white light emitting diodes, the application range of LEDs has also expanded, leaving the market for conventional simple displays and portable liquid crystal displays, and gradually expanding the range of related technologies such as LCD BLU (back light units), electronics, and lighting. It is in great spotlight.

The most problematic issue in such nitride semiconductor light emitting devices is low luminous efficiency. In general, the light efficiency of a nitride semiconductor light emitting device is characterized by the internal quantum efficiency (light quantum efficiency) indicating the degree of light generation and the light extraction efficiency (also called external quantum efficiency) indicating the degree of light exiting the device; It is determined by the efficiency with which light is amplified by the phosphor.

Currently, the problem is that the light extraction efficiency is low. The light extraction efficiency is determined by optical factors of the light emitting device, that is, the refractive index of each structure and the flatness of the interface.

In terms of light extraction efficiency, nitride-based semiconductor light emitting devices have fundamental limitations. That is, since the semiconductor layer constituting the semiconductor light emitting device has a larger refractive index than the external atmosphere or the substrate, the critical angle that determines the range of incidence angles of light emission becomes small, and as a result, a large part of the light generated from the active layer is totally reflected internally. The light extraction efficiency is low because it propagates in a substantially undesired direction or travels inside the device during total reflection and is lost as heat.

In order to solve this problem, a method of forming an uneven structure on the surface where light is transmitted to the outside has been proposed in the related art. As a method of forming the uneven structure, etching using a photoresist is common, in this case, a fine uneven shape Is difficult to form on the surface of the electrode and the nitride semiconductor layer. In addition, defects such as etching stress are present on the unevenness obtained through the photolithography process, so that light emission of the light emitting device is uneven and light extraction efficiency is also lowered. In addition, there is a problem that the process is complicated by additional processes such as photolithography and dry etching to form the unevenness, and the overall process time is long, resulting in lower product yield and increased cost.

The present invention is to solve the above problems, an object of the present invention through the irradiation of a laser beam to the light emitting surface nitride that can easily form a fine pattern for light extraction on the light emitting surface without a complicated process process It is to provide a method of manufacturing a semiconductor light emitting device.

The present invention is a means for solving the above problems, the method of manufacturing a nitride-based semiconductor light emitting device according to an embodiment of the present invention, the first conductive nitride layer, the active layer and the second conductive nitride layer on one surface of the substrate Sequentially growing to form a light emitting structure; Forming a transparent electrode on the second conductive nitride layer; Forming first and second electrodes electrically connected to the first conductive nitride layer and the transparent electrode, respectively; And forming a fine pattern for extracting light by irradiating a laser beam to one surface of the transparent electrode.

In this case, the first electrode may be formed in a portion of the first conductive nitride layer exposed by mesa etching.

In addition, the step of forming the light extracting fine pattern may be performed simultaneously on the surface of the first conductive nitride layer exposed by the mesa etching, and the fine pattern for irregular light extraction through the front irradiation of the laser beam It may proceed to form.

In addition, the light emitting structure, the transparent electrode and a plurality of structures consisting of the first electrode and the second electrode is provided to form an array, wherein the fine pattern for extracting light is to irradiate a plurality of structures simultaneously with a laser beam Can be performed by

According to the present invention, by forming a fine pattern for light extraction on the light emitting surface through the irradiation of the laser beam, not only can the light extraction efficiency of the light emitting device be improved, but also the manufacturing process can be simplified, and thus the process The time can be shortened to increase the mass productivity of the product and reduce the manufacturing cost. In addition, according to the present invention, there is no defect such as etching stress on the upper part of the fine pattern by forming the fine pattern for light extraction by the laser beam, it is possible to obtain a high quality light emitting device with improved light extraction efficiency.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. In addition, embodiments of the present invention is provided to more completely explain the present invention to those skilled in the art. Accordingly, the shape and size of elements in the drawings may be exaggerated for clarity, and the elements denoted by the same reference numerals in the drawings are the same elements.

1 is a side cross-sectional view showing a nitride semiconductor light emitting device according to a first embodiment of the present invention.

As shown in FIG. 1, the nitride semiconductor light emitting device 100 according to the first embodiment includes a substrate 110, a first conductive nitride layer 120, an active layer 130, and a substrate 110. The light emitting structure in which the second conductive nitride layer 140 is sequentially formed, and the transparent electrode 150 formed on the second conductive nitride layer 140 and formed with the fine pattern 180 for light extraction are formed. In addition, the nitride based semiconductor light emitting device 100 may include a second electrode 160 formed in a portion of the transparent electrode 150 and a portion of the first conductive nitride layer 120 exposed through mesa etching. An electrode 170 is provided.

Here, the light emitting structure is a term referring to a structure in which the first conductive nitride layer 120, the active layer 130, and the second conductive nitride layer 140 are sequentially formed on the substrate 110.

In the first embodiment, the substrate 110 is a substrate having excellent thermal conductivity, and serves as a support for supporting the light emitting structure. The substrate 110 may be a substrate made of sapphire substrate, silicon carbide (SiC), oxide or carbide.

In addition, the first conductive type and the second conductive type nitride layers 120 and 140 may have an Al _x In _y Ga _(1-xy) N composition formula, where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, and 0 ≦ x +. y ≦ 1) and the first conductive impurity and the second conductive impurity may be formed of a semiconductor material, and typically GaN, AlGaN, and InGaN. In addition, Si, Ge, Se, Te, or C may be used as the first conductivity type impurity, and Mg, Zn, or Be, and the like are representative of the p-type impurity.

The active layer 130 is a layer in which light is generated by recombination of electrons and holes, and may be formed of a nitride semiconductor layer having a single or multiple quantum well structure. Although a nitride semiconductor is used in the present embodiment, the present invention is not limited thereto, and other kinds of semiconductor materials known in the art may be used.

In addition, the transparent electrode 150 may be formed of ITO, ZnO, or the like, and the transparent electrode 150 has a plurality of fine patterns 180 for light extraction formed on an upper surface thereof. The light extracting fine pattern 180 may have a pyramid shape and the like, and may be irregularly formed by irradiation of the entire surface of the laser beam.

The second electrode 160 and the first electrode 170 may be silver or aluminum having a high reflectance, and particularly preferably silver.

FIG. 2 is a side cross-sectional view for each process for explaining the method for manufacturing the nitride semiconductor light emitting device according to the first embodiment of the present invention shown in FIG. 1. Here, although a plurality of nitride-based semiconductor light emitting devices are manufactured using a predetermined wafer, a method of manufacturing only one light emitting device is illustrated in FIG. 2 for convenience of description. In addition, the same components are denoted by the same reference numerals, and description of the same components is omitted.

First, as shown in FIG. 2 (a), the substrate 110 is prepared. The substrate 110 may be a substrate made of sapphire substrate, silicon carbide (SiC), oxide or carbide.

Subsequently, as shown in FIG. 2 (b), the light emitting structure is grown by sequentially growing the first conductive nitride layer 120, the active layer 130, and the second conductive nitride layer 140 on the substrate 110. Form.

The first conductive nitride layer 120, the active layer 130, and the second conductive nitride layer 140 may be formed by organometallic vapor deposition (MOCVD), molecular beam growth (MBE), and hybrid vapor deposition (HVPE). And so on.

On the other hand, although not shown separately, in order to mitigate lattice mismatch between the first conductive nitride layer 120 and the substrate 110, before the first conductive nitride layer 120 is grown, the substrate 110 is disposed on the substrate 110. The buffer layer (not shown) may be preferentially grown.

Then, the transparent electrode 150 is further formed on the second conductive nitride layer 140. The transparent electrode 150 may perform an ohmic contact function and a current spreading function with the second conductive nitride layer 140.

Subsequently, as shown in FIG. 2C, in the structure obtained as shown in FIG. 2B, the light emitting structure and the transparent electrode 150 are mesa-etched to expose a portion of the first conductive nitride layer 120. do. Next, the second electrode 160 is formed in a portion of the transparent electrode 150, and the first electrode 170 is formed in a portion of the exposed region of the first conductive nitride layer 120.

Subsequently, as shown in FIG. 2 (d), after forming the pattern mask A to expose the transparent electrode 150 and the second electrode 160, the laser beam is irradiated onto the transparent electrode 150 in front of it. The fine pattern 180 for light extraction is formed on the surface. At this time, since the second electrode 160 reflects the laser beam, a fine pattern for light extraction is not formed.

When the fine pattern 380 for light extraction is formed on the surface of the transparent electrode 350 as described above, when the light emitting device 300 of the present embodiment emits light, the light generated in the active layer 330 is transparent to an angle range that causes total reflection. Even when incident on the electrode 350, the light is transmitted from the second conductive nitride layer 340 to the transparent electrode 350 without being totally reflected by the light extracting fine pattern 380 and emitted to the outside. As a result, the problem of lowering the light extraction efficiency of the light emitting device due to the light loss due to total reflection can be solved.

That is, in the present invention, in order to form the light extracting fine pattern 180 on the surface of the transparent electrode 150, a laser beam in the wavelength range of 266nm to 1100nm can be used. In addition, laser beams with sizes ranging from 200 um to 5 mm can be used. By adjusting the wavelength band and size of the laser beam and irradiating the light emitting device chips simultaneously, it is possible to simultaneously form a fine pattern for light extraction by the pulse of the laser beam on the transparent electrode surfaces of the light emitting device chips.

On the other hand, the light emitting structure, the transparent electrode 150 and the structure consisting of a plurality of structures consisting of the first electrode 170 and the second electrode 160 may be formed, and by irradiating a plurality of structures simultaneously with the laser beam The light extracting fine pattern 180 may be formed.

Therefore, fine patterns for light extraction can be simultaneously formed on a plurality of light emitting device chips through one laser beam irradiation, so that the process can be simplified and the processing time can be shortened as compared with the conventional pattern formation. This can increase the mass production of the product, and can reduce the manufacturing cost. In addition, since the fine pattern for light extraction is formed by the laser beam, there is no defect such as an etching stress on the upper portion of the fine pattern, and thus a high quality light emitting device having improved light extraction efficiency can be obtained.

3 is a side cross-sectional view showing a nitride semiconductor light emitting device according to a second embodiment of the present invention.

As shown in FIG. 3, the nitride semiconductor light emitting device 300 according to the second embodiment includes a substrate 310, a first conductive nitride layer 320, an active layer 330, and a substrate 310 on the substrate 310. The light emitting structure in which the second conductive nitride layer 340 is sequentially formed, and the transparent electrode 150 formed on the second conductive nitride layer 340 and formed with a fine pattern 380 for light extraction are included. In addition, the nitride-based semiconductor light emitting device 300 may include a second electrode 360 formed in a portion of the transparent electrode 350 and a portion of the first conductive type nitride layer 320 exposed through mesa etching. An electrode 370 is provided. In addition, the first conductive nitride layer 320 exposed through mesa etching includes a fine pattern 390 for light extraction formed in a region other than the region in which the first electrode 370 is formed.

In the second embodiment, the substrate 310 is a substrate having excellent thermal conductivity, and serves as a support for supporting the light emitting structure. The substrate 310 may be a substrate made of sapphire substrate, silicon carbide (SiC), oxide or carbide.

In addition, the first conductive type and the second conductive type nitride layers 320 and 340 may have Al _x In _y Ga _(1-xy) N composition formulas, where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, and 0 ≦ x +. y ≦ 1) and the first conductive impurity and the second conductive impurity may be formed of a semiconductor material, and typically GaN, AlGaN, and InGaN. In addition, Si, Ge, Se, Te, or C may be used as the first conductivity type impurity, and Mg, Zn, or Be, and the like are representative of the p-type impurity.

The active layer 330 is a layer in which light is generated by recombination of electrons and holes, and may be formed of a nitride semiconductor layer having a single or multiple quantum well structure. Although a nitride semiconductor is used in the present embodiment, the present invention is not limited thereto, and other kinds of semiconductor materials known in the art may be used.

The transparent electrode 350 may be formed of ITO, ZnO, or the like, and the fine pattern 380 for light extraction is formed on the upper surface of the transparent electrode 350 except for the region where the second electrode 360 is formed.

The light extracting fine patterns 380 and 390 may have a pyramid shape and a similar shape, and are irregularly formed by irradiation of the entire surface of the laser beam.

The second electrode 160 and the first electrode 170 may be silver or aluminum having a high reflectance, and particularly preferably silver.

FIG. 4 is a side cross-sectional view for each process for explaining the method for manufacturing the nitride-based semiconductor light emitting device according to the second embodiment of the present invention shown in FIG. 3. Here, a method of manufacturing a nitride-based semiconductor light emitting device is manufactured in plural using a predetermined wafer, but FIG. 4 shows a method of manufacturing only one light emitting device for convenience of description. In addition, the same components are denoted by the same reference numerals, and description of the same components is omitted.

First, as shown in FIG. 4A, a substrate 310 is prepared. The substrate 310 may be a substrate made of sapphire substrate, silicon carbide (SiC), oxide or carbide.

Subsequently, as shown in FIG. 4B, the light emitting structure is grown by sequentially growing the first conductive nitride layer 320, the active layer 130, and the second conductive nitride layer 340 on the substrate 310. Form.

The first conductive nitride layer 320, the active layer 330, and the second conductive nitride layer 340 may be formed by organometallic vapor deposition (MOCVD), molecular beam growth (MBE), hybrid vapor deposition (HVPE), or the like. Can be grown.

On the other hand, although not shown separately, in order to mitigate the lattice mismatch between the first conductive nitride layer 320 and the substrate 310, before the first conductive nitride layer 320 is established, the substrate 310 is disposed on the substrate 310. The buffer layer (not shown) may be preferentially grown.

Then, the transparent electrode 350 is further formed on the second conductive nitride layer 340. The transparent electrode 350 performs an ohmic contact function and a current spreading function with the second conductive nitride layer 340, and the transparent electrode 350 forms a fine pattern for light extraction on the surface to contribute to light emission efficiency. Can be.

Subsequently, as shown in FIG. 4C, in the structure obtained as shown in FIG. 4B, the light emitting structure and the transparent electrode 350 are mesa-etched to expose a portion of the first conductive nitride layer 320. do. Next, the second electrode 360 is formed in a portion of the transparent electrode 350, and the first electrode 370 is formed in a portion of the exposed region of the first conductive nitride layer 320.

Subsequently, as shown in FIG. 4 (d), the laser beam is irradiated onto the entire structure obtained as shown in FIG. 4 (c) to light the surface of the transparent electrode 350 and the exposed first conductive nitride layer 320. Extraction fine patterns 380 and 390 are formed. At this time, since the second electrode 360 and the first electrode 370 reflect the laser beam, a fine pattern for light extraction is not formed even when the laser beam is irradiated.

When the fine pattern 380 for light extraction is formed on the surface of the transparent electrode 350 as described above, when the light emitting device 300 of the present embodiment emits light, the light generated in the active layer 330 is transparent to an angle range that causes total reflection. Even when incident on the electrode 350, the light is transmitted from the second conductive nitride layer 340 to the transparent electrode 350 without being totally reflected by the light extracting fine pattern 380 and emitted to the outside.

In addition, when the fine pattern 390 for light extraction is formed on the surface of the first conductive nitride layer 320, when the light emitting device 300 of the present embodiment emits light, the light generated in the active layer 330 is directly or Even though incident on the substrate 310 in an angular range reflecting the second electrode 360 to cause total reflection, the light is transmitted from the substrate 310 to the first conductive type nitride layer 320 without being totally reflected by the fine pattern for light extraction, and then externally reflected. Is released.

In the present invention, a laser beam of 266 nm to 1100 nm may be used as the laser beam for forming the light extraction fine pattern. In addition, laser beams with sizes ranging from 200 um to 5 mm can be used.

That is, by adjusting the wavelength band and the size of the laser beam, and irradiating the laser beam on the plurality of light emitting device chips at the same time, the light by the pulse of the laser beam on the transparent electrode surface and the surface of the first conductive type nitride layer of the plurality of light emitting device chips. The fine pattern for extraction can be formed simultaneously.

Here, the light emitting structure, the transparent electrode 350 and the structure consisting of a plurality of structures consisting of the first electrode 370 and the second electrode 360 may be formed, and by irradiating a plurality of structures simultaneously with the laser beam Fine patterns 380 and 390 for light extraction may be formed.

Therefore, fine patterns for light extraction can be simultaneously formed on a plurality of light emitting device chips through one laser beam irradiation, so that the process can be simplified and the processing time can be shortened as compared with the conventional pattern formation. This can increase the mass production of the product, and can reduce the manufacturing cost. In addition, since the fine pattern for light extraction is formed by the laser beam, there is no defect such as an etching stress on the upper portion of the fine pattern, and thus a high quality light emitting device having improved light extraction efficiency can be obtained.

The present invention is not limited by the above-described embodiments and the accompanying drawings, but is intended to be limited only by the appended claims. Accordingly, various forms of substitution, modification, and alteration may be made by those skilled in the art without departing from the technical spirit of the present invention described in the claims, which are also within the scope of the present invention. something to do.

1 is a side cross-sectional view showing a nitride semiconductor light emitting device according to a first embodiment of the present invention.

FIG. 2 is a side cross-sectional view for each process for explaining the method for manufacturing the nitride semiconductor light emitting device according to the first embodiment of the present invention shown in FIG. 1.

3 is a side cross-sectional view showing a nitride semiconductor light emitting device according to a second embodiment of the present invention.

FIG. 4 is a side cross-sectional view for each process for explaining the method for manufacturing the nitride-based semiconductor light emitting device according to the second embodiment of the present invention shown in FIG. 3.

Claims (5)

Forming a light emitting structure by sequentially growing a first conductive nitride layer, an active layer, and a second conductive nitride layer on one surface of the substrate; Forming a transparent electrode on the second conductive nitride layer; Forming first and second electrodes electrically connected to the first conductive nitride layer and the transparent electrode, respectively; And And irradiating a laser beam to one surface of the transparent electrode to form a fine pattern for light extraction. The method of claim 1, The first electrode is a method of manufacturing a nitride-based semiconductor light emitting device, characterized in that formed in the partial region of the first conductive nitride layer exposed by mesa etching. The method of claim 2, The fine pattern forming step for light extraction, The method of manufacturing a nitride-based semiconductor light emitting device, characterized in that carried out simultaneously on the surface of the first conductive nitride layer exposed by the mesa etching. The method of claim 1, The fine pattern forming step for light extraction, The method of manufacturing a nitride-based semiconductor light emitting device, characterized in that to proceed to form a fine pattern for irregular light extraction through the front irradiation of the laser beam. The method of claim 1, A plurality of structures including the light emitting structure, the transparent electrode, and the first electrode and the second electrode are provided to form an array, The method of manufacturing a nitride-based semiconductor light emitting device is characterized in that the step of forming a fine pattern for light extraction is performed by simultaneously irradiating the plurality of structures with a laser beam.

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