KR100616631B1 - Nitride based semiconductor light emitting device and method for manufacturing the same - Google Patents

Abstract

A nitride-based semiconductor light emitting device capable of obtaining high luminous efficiency and a method of manufacturing the same are disclosed. The nitride semiconductor light emitting device according to the present invention comprises: an ELOG mask film pattern formed on a substrate; An n-type nitride semiconductor layer formed by ELOG on the substrate exposed by the mask film pattern and the mask film pattern; An active layer formed on the n-type nitride based semiconductor layer; A p-type nitride semiconductor layer formed on the active layer; An electrode blocking layer pattern formed on the p-type nitride based semiconductor layer so as to be aligned with a substrate region other than the mask film pattern; And a p-side electrode layer formed on the p-type nitride semiconductor layer and having a contact portion with the p-type nitride semiconductor layer aligned with the mask film pattern. The p-side electrode layer covers the p-type nitride based semiconductor layer and the electrode blocking layer pattern exposed by the electrode blocking layer pattern.

Nitride-based semiconductor light emitting device, ELOG

Description

Nitride-based semiconductor light emitting device and method of manufacturing the same {NITRIDE BASED SEMICONDUCTOR LIGHT EMITTING DEVICE AND METHOD FOR MANUFACTURING THE SAME}

1 is a schematic cross-sectional view of a conventional nitride semiconductor light emitting device.

2 is a view schematically showing a cross-sectional structure of a nitride-based semiconductor light emitting device according to an embodiment of the present invention.

3 to 7 are cross-sectional views illustrating a method of manufacturing a nitride-based semiconductor light emitting device according to an embodiment of the present invention.

8 and 9 are cross-sectional views illustrating a method of manufacturing a nitride-based semiconductor light emitting device according to another embodiment of the present invention.

10 and 11 are plan views illustrating the shape of a p-side electrode of a nitride-based semiconductor light emitting device manufactured according to various embodiments of the present disclosure.

12 is a cross-sectional view illustrating a nitride-based semiconductor light emitting device according to an embodiment of the present invention.

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

101: substrate 102: mask pattern for ELOG

104: n-type GaN layer 106: active layer

108: p-type GaN layer 110: electrode blocking layer pattern

112: p-side electrode layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nitride based semiconductor light emitting device and a method of manufacturing the same. More particularly, the light emitting part is arranged in a region having a low dislocation by aligning the shape and position of the upper electrode with a mask pattern for ELOG. A nitride-based semiconductor light emitting device exhibiting efficiency and a method of manufacturing the same.

In recent years, nitride semiconductors have attracted attention as materials suitable for short-wavelength optoelectronic devices and high-performance electronic devices applications. In particular, blue and green light emitting diodes made of GaN compound semiconductors have been commercialized in the late 1990s. White light emitting diodes are also manufactured from GaN-based compound semiconductors, which have recently been commercialized and are rapidly increasing in demand. However, there is a problem that the nitride-based single crystal growth substrate that is matched with the lattice constant and thermal expansion coefficient of the nitride-based single crystal is not common.

Nitride films (thin films such as InN, AlN, GaN, AlGaN, InGaN, etc.) typically represented by GaN thin films are formed on heterogeneous substrates such as sapphire substrates, SiC substrates, or Si substrates due to technical difficulties in forming nitride substrates. As a result, nitride films grown on heterogeneous substrates contain many defects, particularly dislocations, due to differences in crystal constants and thermal expansion coefficients between the substrate and the nitride film.

1 is a schematic cross-sectional view of a conventional nitride semiconductor light emitting device. Referring to FIG. 1, an n-type GaN-based semiconductor layer 12, an active layer 14 and a p-type GaN-based semiconductor layer 16 are sequentially stacked on a sapphire or SiC substrate 11, and an upper electrode, The p-side electrode 18 is formed. In such a structure, since the difference in thermal expansion coefficient and lattice constant between the substrate 11 and the n-type GaN-based semiconductor layer 12 is very large, the semiconductor layers 12, 14, and 16 contain many potentials. This potential not only disturbs the flow of holes, but also acts as a non-radiative recombination center in the active layer 14 to reduce the light efficiency of the light emitting device.

In order to solve this potential defect problem, various methods have been proposed. For example, a low temperature AlN buffer layer or a buffer structure in which AlGaN / GaN layers are combined is formed on a substrate, and then a GaN epitaxial layer is formed thereon. . However, the formation of the GaN layer in this manner does not fundamentally improve the problem of lattice mismatch, so that there are considerable dislocation defects in the GaN thin film.

Another solution to the problem of dislocation defects is epitaxial lateral overgrowth (ELOG). In this epitaxial lateral overgrowth method, before forming a GaN thin film on a substrate, a mask film pattern is formed on the substrate to prevent the growth of the GaN thin film. Thereafter, GaN is grown so that the GaN thin film is formed only on the substrate region exposed by the mask film pattern. Subsequently, the growth direction of GaN is gradually adjusted in the direction (lateral direction) parallel to the substrate, resulting in a flat GaN thin film having a low dislocation density on the substrate.

By the way, even when a GaN thin film is formed by such an ELOG method, it is known that the portion where the growth of the GaN thin film is started has a much higher dislocation density than the portion where the growth of the GaN thin film is suppressed. Therefore, in the region having a high dislocation density, light emission does not occur well even when a current is injected.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and to provide a nitride-based semiconductor light emitting device capable of realizing a high luminous efficiency by suppressing a reduction in luminous efficiency due to a potential defect in a nitride-based semiconductor layer. .

Further, another object of the present invention is to provide a method for manufacturing a nitride-based semiconductor light emitting device capable of suppressing the phenomenon of a decrease in luminous efficiency due to a potential defect in the nitride-based semiconductor layer formed by the ELOG method.

In order to achieve the above technical problem, the nitride-based semiconductor light emitting device according to the present invention comprises a mask film pattern for ELOG formed on a substrate; An n-type nitride semiconductor layer formed by ELOG on the substrate exposed by the mask film pattern and the mask film pattern; An active layer formed on the n-type nitride based semiconductor layer; A p-type nitride semiconductor layer formed on the active layer; An electrode blocking layer pattern formed on the p-type nitride based semiconductor layer so as to be aligned with a substrate region other than the mask film pattern; And a p-side electrode layer formed on the p-type nitride semiconductor layer and having a contact portion with the p-type nitride semiconductor layer aligned with the mask film pattern. The p-side electrode layer covers the p-type nitride based semiconductor layer and the electrode blocking layer pattern exposed by the electrode blocking layer pattern.

According to one embodiment of the present invention, the electrode blocking layer pattern may be formed of an insulating layer, such as a SiO ₂ layer.

In the semiconductor light emitting device of the present invention, the n-type nitride-based semiconductor layer and the p-type nitride-based semiconductor layer may be made of GaN, AlGaN, InGaN, AlGaInN, AlN or InN or a combination thereof. For example, the semiconductor layers may be a stacked structure of a GaN layer and an AlGaN layer, or may be a thin film representing a super lattice. In addition, the mask layer pattern may be formed of an insulating layer such as SiO ₂ or SiN.

According to an embodiment of the present invention, the planar structure of the contact portion between the electrode and the p-type nitride-based semiconductor layer may be in the form of a stripe. Further, according to another embodiment, the planar structure of the contact portion may be in the form of a dot or island.

In order to achieve another technical problem of the present invention, a method of manufacturing a nitride-based semiconductor light emitting device according to the present invention, forming a mask film pattern for ELOG on the substrate; Growing an p-type nitride semiconductor layer from the substrate surface exposed by the mask film pattern to ELOG to form an n-type nitride semiconductor layer on the exposed substrate surface and the mask film pattern; Sequentially forming an active layer and a p-type nitride-based semiconductor layer on the n-type nitride-based semiconductor layer; Forming an electrode blocking layer pattern on the p-type nitride based semiconductor layer to align the electrode blocking layer pattern with a substrate region other than the mask film pattern; And forming a p-side electrode layer on the p-type nitride based semiconductor layer so that the contact portion between the p-type nitride based semiconductor layer and the p-side electrode layer is aligned with the mask film pattern. The p-side electrode layer is formed to cover the p-type nitride semiconductor layer and the electrode blocking layer pattern exposed by the electrode blocking layer pattern.

According to one embodiment of the present invention, the electrode blocking layer pattern may be formed of SiO ₂ .

According to the present invention, when the nitride based semiconductor layer is grown by the ELOG method, the light emitting portion is limited to the low potential region so that the electron-holes recombine in the region where the potential defect is low. Accordingly, it is possible to prevent the phenomenon of decrease in luminous efficiency due to potential defects, thereby realizing high luminous efficiency.

Hereinafter, 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. Embodiments of the present invention are 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.

2 is a view schematically showing a cross-sectional structure of a nitride-based semiconductor light emitting device according to an embodiment of the present invention. 2, an ELOG mask film pattern 102, an n-type GaN layer 104, an active layer 106, and a p-type GaN layer 108 are sequentially formed on the substrate 101. The active layer 106 may be formed of, for example, a single or multi quantum well structure of InGaN / GaN, but is not limited thereto. The electrode blocking layer 110 in the form of a pattern is formed thereon. The electrode blocking layer pattern 110 is alternately arranged with the mask film pattern 102 so as to be aligned with a substrate region other than the mask film pattern 102. The p-side electrode layer 112 is formed on the electrode blocking layer pattern 110 and the surface of the p-type GaN layer 108 exposed thereby.

Referring to FIG. 2, the n-type GaN layer 104 is a semiconductor layer grown by the ELOG method and has a low dislocation defect density in a region where the mask film pattern 102 is formed as compared with a region in contact with the substrate 101. Will have Accordingly, the active layer 106 and the p-type GaN layer 108 also have a relatively low dislocation defect density in the region aligned with the mask film pattern 102.

Since the portion of the p-type GaN layer 108 into which the actual current is injected is the portion in contact with the p-side electrode layer 112, the current applied through the p-side electrode layer 112 may have a low potential defect density region (mask film pattern 102). ) In the form of holes (h +). However, holes have a property that diffusion is hardly achieved due to low conductivity and mobility. Therefore, the region in which current flows in the form of a hole (h +) in the p-type GaN layer 108 is defined as a region having a low dislocation defect density (region aligned with the mask film pattern 102).

On the other hand, in the n-type GaN layer 104, electrons are charge carriers. Since the conductivity and mobility of the electrons are relatively high, in the n-type nitride-based semiconductor region 104, electrons (e-) are less affected by dislocation defects and go to the active layer 106 at a high speed and the p-type GaN layer 108 Recombine with the hole (h +) coming from. Therefore, the electron (e−) and the hole (h +) are recombined in the portion of the active layer 106 in the region where the potential defect is low, so that the light emitting device exhibits high luminous efficiency.

In the above embodiment, a GaN layer is used as the n-type or p-type nitride-based semiconductor layers 104 and 108, but a layer made of GaN, AlGaN, InGaN, AlGaInN, AlN, or InN or a combination thereof may be used instead of the GaN layer. have. For example, the n-type or p-type nitride based semiconductor layers 104 and 108 may be a stacked structure of a GaN layer and an AlGaN layer, or may be a thin film having a superlattice structure.

3 to 7 are cross-sectional views illustrating a method of manufacturing a nitride-based semiconductor device according to an embodiment of the present invention.

First, referring to FIG. 3, a mask film pattern 102 for ELOG is formed on a substrate 101 made of sapphire, SiC, Si, or the like. The mask film pattern 102 may be formed of, for example, an insulating film such as SiO ₂ or SiN.

Next, as shown in FIG. 4, an n-type GaN layer 104 is formed on the structure on which the mask film pattern 102 is formed by ELOG. That is, the n-type GaN layer 104 is grown from the surface area of the substrate 101 exposed by the mask film pattern 102. Accordingly, the growth direction of the GaN layer 104 is gradually adjusted laterally so that the n-type GaN layer 104 completely covers the mask film pattern 102. At this time, the region where the growth of the n-type GaN layer 104 is suppressed (that is, the region aligned with the mask film pattern 102) has a lower dislocation defect density than the portion where the growth of the GaN layer 104 has started. do. Since the dislocation defects act as non-radioactive recombination centers, the luminous efficiency is low in the region with high dislocation defect density, while the luminous efficiency is excellent in the region with low dislocation defect density.

Next, as shown in FIG. 5, the active layer 106 and the p-type GaN layer 108 are formed on the n-type GaN layer 104. As described above, the region where the growth of the type GaN layer 104 is suppressed has a dislocation defect of a lower density than the portion where the growth of the GaN layer 104 has started, and thus the region aligned with the mask film pattern 102. Portions of the active layer 106 and the p-type GaN layer 108 also have low density of potential defects.

Next, as shown in FIG. 6, the electrode blocking layer pattern 110 is formed to be crossed with the mask film pattern 102 (that is, aligned with a substrate region other than the mask film pattern 102). The electrode blocking layer pattern 110 may be formed of, for example, an insulating layer such as a SiO ₂ layer. Thereafter, as shown in FIG. 7, the p-side electrode layer 112 is formed on the resultant. Accordingly, the p-layer electrode layer 112 is in contact with the p-type GaN layer 108 only in the region aligned with the mask film pattern 102. Therefore, as described above, holes are injected from the P-type GaN layer 108 in the low dislocation defect density region to recombine with electrons in the active layer in the low dislocation defect density region. Therefore, the luminous efficiency of the light emitting element is increased.

8 and 9 are cross-sectional views illustrating a method of manufacturing a nitride-based semiconductor light emitting device according to another embodiment. In this embodiment, the electrode blocking layer pattern is not formed. Instead, the electrode metal layer is patterned so that the p-side electrode layer is formed only in the region aligned with the mask film pattern. Also in this embodiment, as in the above-described embodiment, after performing the processes described with reference to FIGS. 3 and 4, the active layer 106 and the p-type GaN layer 108 are sequentially formed to have a structure as shown in FIG. 8. Get

Next, as shown in FIG. 9, the p-side electrode layer 114 is formed on the p-type GaN layer 108 to be aligned with the mask film pattern 102. Also in this embodiment, the region where the actual current is injected and the region where electron-hole recombination occurs in the p-type GaN layer 108 have low dislocation defect densities, thereby enabling high luminous efficiency.

According to the present invention, since the p-side electrode layer 112 in contact with the p-type GaN layer 108 is aligned with the mask film pattern 102, the p-side electrode layer 112 in contact with the p-type GaN layer 108. The pattern shape of V is different depending on the shape of the mask film pattern 102. Examples of the pattern shape of the portion of the P-side electrode layer 112 are illustrated in FIGS. 10 and 11.

10 and 11 illustrate the shapes of the contact portions 110a and 110b between the p-type GaN layer and the p-side electrode layer. In FIG. 10, a contact portion pattern 110a having a stripe shape is shown. A contact pattern 110b in the form of an island or a dot is shown. 10 and 11, the electrode blocking layer patterns 112a and 112b are formed in regions other than the contact portion patterns 110a and 110b of the p-side electrode layer.

12 is a cross-sectional view illustrating a nitride-based semiconductor light emitting device according to an embodiment of the present invention. The nitride semiconductor light emitting device illustrated in FIG. 12 is a light emitting device manufactured using the manufacturing method described with reference to FIGS. 8 and 9, and in FIG. 12, not only the p-side electrode layer 114 but also the n-side electrode layer 116. Is shown. 12, an n-type GaN layer 104, an active layer 106, and a p-type GaN layer 108 grown on the substrate 101 made of sapphire or the like by the ELOG mask film pattern 102, the ELOG method. ) Are formed sequentially. A pattern of the p-side electrode 114 is formed on the p-type GaN layer 108 to align with the mask layer pattern 102 for ELOG, and an n-side electrode on one side of the n-type GaN layer 104 exposed by etching. 116 is formed. According to the present embodiment, since the region where the electron-hole recombination occurs has a low dislocation defect density, high luminous efficiency can be realized in actual operation. In this embodiment, although the n-side electrode 116 is located on one side of the n-type GaN layer 104 etched and exposed to form a mesa structure, the n-side electrode 116 may have a different arrangement.

It is intended that the invention not be limited by the foregoing embodiments and the accompanying drawings, but rather by the claims appended hereto. In addition, it will be apparent to those skilled in the art that the present invention may be substituted, modified, and changed in various forms without departing from the technical spirit of the present invention described in the claims.

As described above, according to the present invention, a nitride-based semiconductor light emitting device having a high luminous efficiency can be obtained by aligning the contact portion of the p-side electrode layer and the ELOG mask film pattern with each other to limit the light emitting region to a region having a low dislocation defect density. Will be.

Claims (11)

A mask film pattern for ELOG formed on the substrate; An n-type nitride semiconductor layer formed by ELOG on the substrate exposed by the mask film pattern and the mask film pattern; An active layer formed on the n-type nitride based semiconductor layer; A p-type nitride semiconductor layer formed on the active layer; An electrode blocking layer pattern formed on the p-type nitride based semiconductor layer so as to be aligned with a substrate region other than the mask layer pattern; And A p-side electrode layer formed on the p-type nitride-based semiconductor layer and having a contact portion with the p-type nitride-based semiconductor layer aligned with the mask film pattern, And the p-side electrode layer covers the p-type nitride semiconductor layer and the electrode blocking layer pattern exposed by the electrode blocking layer pattern. delete The method of claim 1, The electrode blocking layer pattern is a nitride-based semiconductor light emitting device, characterized in that consisting of a SiO ₂ layer. delete The method of claim 1, The n-type nitride-based semiconductor layer and the p-type nitride-based semiconductor layer, GaN, AlGaN, InGaN, AlGaInN, AlN or InN or a combination of the nitride-based semiconductor light emitting device, characterized in that. The method of claim 1, The mask layer pattern is a nitride-based semiconductor light emitting device, characterized in that consisting of SiO ₂ or SiN. The method of claim 1, The contact portion of the p-side electrode layer is a nitride-based semiconductor light emitting device, characterized in that the stripe form. The method of claim 1, The contact portion of the p-side electrode layer is a nitride-based semiconductor light emitting device, characterized in that the form of points or islands. Forming a mask film pattern for ELOG on the substrate; Growing an p-type nitride semiconductor layer from the substrate surface exposed by the mask film pattern to ELOG to form an n-type nitride semiconductor layer on the exposed substrate surface and the mask film pattern; Sequentially forming an active layer and a p-type nitride-based semiconductor layer on the n-type nitride-based semiconductor layer; Forming an electrode blocking layer pattern on the p-type nitride based semiconductor layer to align the electrode blocking layer pattern with a substrate region other than the mask layer pattern; And Forming a p-side electrode layer on the p-type nitride based semiconductor layer to align the contact portion between the p-type nitride based semiconductor layer and the p-side electrode layer with the mask film pattern, The p-side electrode layer is formed to cover the p-type nitride semiconductor layer and the electrode blocking layer pattern exposed by the electrode blocking layer pattern, characterized in that the manufacturing method of the nitride-based semiconductor light emitting device. delete delete

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