WO2016064258A1

WO2016064258A1 - Nitride semiconductor light emitting element and method for manufacturing same

Info

Publication number: WO2016064258A1
Application number: PCT/KR2015/011334
Authority: WO
Inventors: 이용석; 심현욱; 권태완
Original assignee: 일진엘이디(주)
Priority date: 2014-10-24
Filing date: 2015-10-26
Publication date: 2016-04-28
Also published as: KR20160049180A

Abstract

Disclosed are a nitride semiconductor light emitting element having excellent crystallinity and brightness characteristics and a method for manufacturing the same. The nitride semiconductor light emitting element according to the present invention comprises: a substrate having a convexo-concave pattern formed on a surface thereof; silica formed in the particle form on a surface of the substrate, to expose a part of the substrate; a lower nitride semiconductor layer formed on the silica and the exposed surface of the substrate; and a multilayered light emitting structure formed on the lower nitride semiconductor layer and comprising a first conductive type nitride semiconductor layer, an active layer, and a second conductive type nitride semiconductor layer.

Description

Nitride semiconductor light emitting device and its manufacturing method

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nitride semiconductor light emitting device manufacturing technology, and more particularly, to a nitride semiconductor light emitting device capable of improving crystal quality and luminance by using a substrate and a silica on which an uneven pattern is formed, and a manufacturing method thereof.

The light emitting device is mainly manufactured by epitaxially growing a nitride semiconductor on a growth substrate.

The growth substrate used for manufacturing the light emitting device uses a material such as gallium nitride (GaN), sapphire, silicon, or the like.

The gallium nitride substrate has the same or almost no difference in lattice constant from the nitride semiconductor, so that a high quality epi thin film can be obtained, but the price of the substrate itself is very expensive, which is a limiting factor.

In addition, although the silicon substrate has an advantage of low cost, there is a problem in that the crystal quality of the nitride semiconductor is not good because the difference in lattice constant with the nitride semiconductor is very large.

For this reason, sapphire substrates which are cheaper than gallium nitride substrates and have relatively smaller lattice constant differences from nitride semiconductors than silicon are most commonly used as substrates for manufacturing nitride semiconductor light emitting devices.

Conventionally, a sapphire substrate having a flat surface has been used. However, when the uneven pattern is formed on the surface of the sapphire substrate is known to improve the light extraction, and also to improve the crystal quality of the nitride semiconductor, recently the uneven pattern on the surface is called the PSS (Patterned Sapphire Substrate) The formed sapphire substrate is most used.

Prior art related to the present invention includes a pattern sapphire substrate disclosed in Republic of Korea Patent Publication No. 10-2011-0024762 (published on March 9, 2011) and a light emitting device using the same.

One object of the present invention is to provide a nitride semiconductor light emitting device capable of improving crystal quality and brightness by using a substrate and a silica on which an uneven pattern is formed.

Another object of the present invention is to provide a method of manufacturing a nitride semiconductor light emitting device using a substrate and an uneven patterned silica.

According to an embodiment of the present invention, a nitride semiconductor light emitting device includes: a substrate having an uneven pattern formed on a surface thereof; Silica formed in a single layer in the form of particles so that the substrate is partially exposed on the surface of the substrate; A lower nitride semiconductor layer formed on the silica and exposed substrate surfaces; And a multilayer light emitting structure formed on the lower nitride semiconductor layer and including a first conductivity type nitride semiconductor layer, an active layer, and a second conductivity type nitride semiconductor layer.

In this case, the uneven pattern of the substrate may include a plurality of convex portions, and may be flat between the plurality of convex portions.

In addition, the uneven pattern of the substrate may include a plurality of convex portions, and may be concave between the plurality of convex portions.

In addition, the silica preferably has a diameter of 0.3 ~ 1㎛.

In addition, the lower nitride semiconductor layer may be formed of a nitride semiconductor or a first conductivity type nitride semiconductor which is not doped with impurities, or may be formed of a stacked structure thereof.

In addition, the substrate is preferably made of sapphire material.

According to another aspect of the present invention, there is provided a method of manufacturing a nitride semiconductor light emitting device, the method including: applying a single layer of silica to a substrate having a concave-convex pattern formed on a surface thereof; Growing a nitride semiconductor from the surface of the substrate exposed between the silica to form a lower nitride semiconductor layer; And forming a multilayer light emitting structure on the lower nitride semiconductor layer, the multilayer light emitting structure including a first conductivity type nitride semiconductor layer, an active layer, and a second conductivity type nitride semiconductor layer.

In this case, the silica coating step may use a spin coating method. In this case, the silica coating step is the step of loading the substrate in the spin coater, providing a silica solution containing silica and a solvent on the substrate, and rotating the spin coater at a first rotational speed to spread over the substrate And increasing the dispersion degree of silica by rotating the spin coater at a second rotation speed faster than the first rotation speed, and removing the solvent through drying. At this time, the silica solution includes 3 wt% or less of silica, and the second rotational speed is preferably 2000 to 4500 RPM.

In addition, the silica preferably has a diameter of 0.3 ~ 1㎛.

In addition, the uneven pattern of the substrate may include a plurality of convex portions, and may be flat between the plurality of convex portions.

In the method for manufacturing a nitride semiconductor light emitting device according to the present invention, after a single layer of silica is applied to a substrate having an uneven pattern formed on its surface, growth of the nitride semiconductor is performed from the exposed sapphire substrate between the silica.

As a result, in the case of the nitride semiconductor light emitting device according to the present invention, the dislocation density was lower than in the case where the nitride semiconductor was grown using only the substrate having the uneven pattern formed on the surface thereof. This can be seen as a result of blocking some of the dislocation generated during the growth of nitride semiconductor.

In addition, in the case of the nitride semiconductor light emitting device according to the present invention, it is possible to scatter light from which silica is extracted in a downward direction.

Therefore, the light emitting device according to the present invention has an advantage of excellent overall light extraction efficiency through crystal quality improvement and scattering inducing effect.

1 illustrates an example in which silica is applied as a single layer to a substrate having an uneven pattern.

2 illustrates a nitride semiconductor light emitting device using the substrate of FIG. 1.

3 shows another example in which silica is applied as a single layer to a substrate having an uneven pattern.

4 illustrates a nitride semiconductor light emitting device using the substrate of FIG. 3.

5 and 6 show top and side SEM images of the silica-coated substrate when the silica solution containing 5 wt% silica is used.

7 and 8 show top and side SEM images of the silica coated substrate when using a silica solution containing 1% by weight of silica (Example 1).

[Description of the code]

110, 310: Substrate

115, 315: uneven pattern

120, 320: Silica

210, 410; Lower nitride semiconductor layer

220, 420: multi-layered light emitting structure

Advantages and features of the present invention, and methods for achieving them will be apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the present embodiments are intended to complete the disclosure of the present invention, and the general knowledge in the art to which the present invention pertains. It is provided to fully convey the scope of the invention to those skilled in the art, and the present invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

Hereinafter, a nitride semiconductor light emitting device and a method of manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 illustrates an example in which silica is applied as a single layer to a substrate having an uneven pattern, and FIG. 2 illustrates a nitride semiconductor light emitting device using the substrate of FIG. 1.

The illustrated nitride semiconductor light emitting device includes a substrate 110, a silica 120, a lower nitride semiconductor layer 210, and a multilayer light emitting structure 220.

The substrate 110 may be formed of a known material such as sapphire, silicon, GaN, and more preferably sapphire.

The substrate 110 has a concave-convex pattern 115 including convex portions on its surface. As described above, when the uneven pattern is formed on the surface of the substrate, there is an effect of improving the crystal quality and the light extraction.

In FIG. 1, the concave-convex pattern 115 of the substrate includes a plurality of convex portions, but a flat shape is formed between the plurality of convex portions.

The silica 120 is formed between the uneven surface 115 of the substrate 110 and between the uneven and uneven surfaces. The silica 120 may be formed only between the unevenness and the unevenness in some cases, for example, as shown in FIG. 3.

The silica 120 improves crystal quality by blocking some of dislocations generated during nitride semiconductor growth, and improves light extraction efficiency by scattering light extracted downward.

In the case of the present invention, it is formed in a single layer using silica in the form of particles. When a gapless silica film is formed, a nitride semiconductor is formed on silica. In this case, the difference in lattice constant between the silica and the nitride semiconductor is so large that the crystal quality is greatly reduced. In addition, even in the form of particles, when silica is formed in multiple layers, there is a problem in that nitride semiconductor growth is not properly performed. However, in the present invention, since the substrate 120 is exposed between the silica and the silica by forming the silica 120 in the form of a single layer, and the nitride semiconductor grows from the exposed substrate, there is a problem in crystal quality when the nitride semiconductor is grown. Rather, silica can play a role in blocking dislocations, thereby improving crystal quality.

It is preferable that silica has a diameter of 0.3-1 micrometer. When using silica having a mean diameter of less than 0.3 μm, so-called nano silica, it is difficult to form a single layer of silica powder on the substrate, and also due to the problem that the exposed portion of the substrate for growing the nitride semiconductor is too small, Growth of nitride semiconductors is difficult However, when the size of the silica is too large, the horizontal growth of the nitride semiconductor is limited, the silica preferably has a diameter of 1㎛ or less.

The silica 120 may be attached to the surface of the substrate 110 through spin coating.

Silica coating using spin coating loads the substrate onto the spin coater, provides a silica solution containing silica and solvent on the substrate, rotates the spin coater at a first rotational speed to spread across the substrate, and then rotates the first rotation. By rotating the spin coater at a second rotation speed faster than the speed to increase the dispersion of silica, it can be made through a series of processes to remove the solvent through drying.

The silica solution for spin coating is preferably one containing 3% by weight or less of silica in a solvent such as alcohol, more preferably 0.5 to 2% by weight in terms of coating amount and dispersibility. If the silica content in the silica solution exceeds 3% by weight, silica agglomeration may occur during the spin coating process, and it becomes difficult to form a single layer.

On the other hand, since the silica aggregation phenomenon may occur when the second rotational speed is too slow, the second rotational speed is preferably 2000 RPM or more. However, since the film uniformity may be lowered if the second rotational speed is too fast, the second rotational speed is more preferably 2000 to 4500 RPM.

The main influences on silica dispersion during spin coating are silica size, silica content in the silica solution, and rotation speed of the spin coater. At this time, when the silica size is too small, less than 0.3㎛, the silica content in the silica solution is more than 3% by weight, or the rotational speed of the spin coater is too small, less than 2000RPM, silica agglomeration may occur, a single layer formation This can be difficult. Accordingly, there may be a problem in that merging is not performed properly when the nitride semiconductor is grown.

The lower nitride semiconductor layer 210 is formed on the surface of the silica 120 and the exposed substrate 110.

The lower nitride semiconductor layer 210 is formed to improve crystal quality, surface planarity, and the like.

The lower nitride semiconductor layer 210 may be formed of a nitride semiconductor or a first conductivity type nitride semiconductor that is not doped with impurities, and may be formed of a stacked structure thereof.

The lower nitride semiconductor layer 210 may be formed using an epitaxial lateral over growth (ELOG) growth method for merging and dislocation bending of the nitride semiconductor to be grown.

The multilayer light emitting structure 220 is formed on the lower nitride semiconductor layer 210 and includes a first conductivity type nitride semiconductor layer, an active layer, and a second conductivity type nitride semiconductor layer.

The active layer can be formed, for example, in a structure in which InGaN / GaN are alternately stacked. In the active layer, light having a predetermined wavelength is generated while electrons supplied from the n-type nitride semiconductor layer and holes supplied from the p-type nitride semiconductor layer are recombined.

The first conductivity type nitride semiconductor layer and the second conductivity type nitride semiconductor layer are formed of nitride doped with impurities of opposite types to each other. For example, if the first conductivity type nitride semiconductor layer is formed of a nitride semiconductor doped with n-type impurities such as Si, the second conductivity-type nitride semiconductor layer may be formed of nitride doped with p-type impurities such as Mg. .

FIG. 3 illustrates another example in which a single layer of silica is applied to a substrate having an uneven pattern, and FIG. 4 illustrates a nitride semiconductor light emitting device using the substrate of FIG. 3.

In the case of the nitride semiconductor light emitting device shown in FIG. 4, the substrate 310 having the uneven pattern 315 formed on the surface thereof, the silica 320 being formed in a single layer, and the lower nitride semiconductor layer 410 formed thereon. And the multilayered light emitting structure 420 is common to the nitride semiconductor light emitting device shown in FIG.

However, in the case of the nitride semiconductor light emitting device shown in FIG. 4, the uneven pattern of the substrate includes a plurality of convex portions, and is different from the nitride semiconductor light emitting device shown in FIG. 2 in that the plurality of convex portions are concave. .

When using a substrate having a concave-convex shape between the concave-convex and concave-convex, such as the example shown in FIGS. It is easy to form a single layer, and as the nitride semiconductor growth in the substrate is made as the substrate exposed surface is increased, a flat GaN thin film can be easily obtained.

That is, as shown in FIGS. 1 and 2, when a substrate having a flat shape between the unevenness and the unevenness is used, and the silica is dispersed throughout the substrate area in the form of particles so that the substrate is partially exposed, the diffuse reflection point is formed. It is possible to increase the light scattering effect with increasing.

On the other hand, when using a substrate having a concave and concave-convex shape between the concave-convex and concave-convex, as shown in the example shown in Figs. Which is advantageous for merging and cross-sectional growth during nitride semiconductor growth, wherein the concave portion of the substrate has a larger contact area than the flat or convex portion of the substrate, so that forming silica in the concave portion disperses the silica over the entire area. It is easy to form more.

Table 1 shows the change in dislocation density and luminous efficiency when a light emitting device was manufactured under the same conditions using a substrate according to Comparative Examples and Examples.

In Table 1, Comparative Example 1 uses a sapphire substrate on which a concave-convex pattern is formed but does not apply silica, and Example 1 has a concave-convex pattern formed on the surface in the same form as Comparative Example 1, but shown in FIG. As shown in the figure, a sapphire substrate coated with silica is used.

In each example, the uneven | corrugated pattern applied the uneven | corrugated height 1.6 micrometer, the size 2.45 micrometer, and the uneven | corrugated spacing 0.3 micrometer. In addition, the unevenness was formed in a hemispherical shape, and the unevenness and the unevenness were flat.

Silica was used having a diameter of approximately 500 nm.

Silica coating was performed using spin coating, and the methanol solution containing 1% by weight of silica was spread on the substrate by spin coating at 1000 RPM for 10 seconds and then spin coating at 4000 RPM for 40 seconds to form silica on the substrate. Then dried.

The dislocation density was indirectly evaluated by the ratio of the area of the non-luminescent area to the total area after the CL measurement.

The luminous efficiency was evaluated by the integrating sphere luminous output value, the integrating sphere luminous output was 100% when the light emitting device was manufactured on the sapphire substrate on which the irregularities were formed on the surface, and the rest showed relative values.

Table 1

Referring to Table 1, in Example 1 in which a single layer of silica was formed on a sapphire substrate having irregularities on its surface, the dislocation density was relatively low and the luminescence properties were increased. This can be seen as a potential blocking and scattering effect of silica.

5 and 6 show top and side SEM pictures of a silica coated substrate when using a silica solution containing 5 wt% silica, and FIGS. 7 and 8 show a silica solution containing 1 wt% silica. Top and side SEM photographs of the silica-coated substrate in the case of Example 1 are shown.

Referring to FIGS. 5 and 6, when the silica solution having a high silica content is used, the exposed portion of the sapphire substrate is hardly seen, and it can be seen that the silica is formed in multiple layers. On the other hand, referring to Figures 7 and 8, when using a silica solution with a low silica content, the exposed portion of the sapphire substrate is relatively wide, it can be seen that the silica is formed in a single layer. As described above, when the silica is formed in a single layer in the form of particles, the increase of the substrate exposed portion is advantageous for the growth of the nitride semiconductor, and also the potential blocking and scattering effect can be obtained by the silica.

Although the above has been described with reference to the embodiments of the present invention, various changes and modifications can be made at the level of those skilled in the art. Such changes and modifications can be said to belong to the present invention without departing from the scope of the technical idea provided by the present invention. Therefore, the scope of the present invention will be determined by the claims described below.

Claims

A substrate having an uneven pattern formed on a surface thereof;

Silica formed in a single layer in the form of particles so that the substrate is partially exposed on the surface of the substrate;

A lower nitride semiconductor layer formed on the silica and exposed substrate surfaces; And

And a multilayer light emitting structure formed on the lower nitride semiconductor layer and including a first conductivity type nitride semiconductor layer, an active layer, and a second conductivity type nitride semiconductor layer.
The method of claim 1,

The uneven pattern of the substrate includes a plurality of convex portions, the nitride semiconductor light emitting device, characterized in that the flat between the plurality of convex portions.
The method of claim 1,

The uneven pattern of the substrate includes a plurality of convex portions, the nitride semiconductor light emitting device, characterized in that the concave between the plurality of convex portions.
The method of claim 1,

The silica is a nitride semiconductor light emitting device, characterized in that having a diameter of 0.3 ~ 1㎛.
The method of claim 1,

The lower nitride semiconductor layer is formed of a nitride semiconductor or a first conductivity type nitride semiconductor which is not doped with impurities, or formed of a stacked structure thereof.
The method of claim 1,

The substrate is a nitride semiconductor light emitting device, characterized in that the sapphire material.
Applying a single layer of silica onto a substrate having an uneven pattern formed on a surface thereof;

Growing a nitride semiconductor from the surface of the substrate exposed between the silica to form a lower nitride semiconductor layer; And

Forming a multilayer light emitting structure including a first conductivity type nitride semiconductor layer, an active layer, and a second conductivity type nitride semiconductor layer on the lower nitride semiconductor layer.
The method of claim 7, wherein

The silica coating step

A method of manufacturing a nitride semiconductor light emitting device, characterized by using a spin coating method.
The method of claim 8,

The silica coating step

Loading the substrate into the spin coater;

Providing a silica solution comprising silica and a solvent on a substrate, rotating the spin coater at a first rotational speed to spread over the substrate;

Increasing the dispersion of silica by rotating the spin coater at a second rotation speed faster than the first rotation speed;

Method of manufacturing a nitride semiconductor light emitting device comprising the step of removing the solvent through drying.
The method of claim 9,

The silica solution comprises less than 3% by weight of silica, the second rotational speed is 2000 ~ 4500 RPM manufacturing method of the nitride semiconductor light emitting device characterized in that.
The method of claim 7, wherein

The silica is a nitride semiconductor light emitting device manufacturing method characterized in that having a diameter of 0.3 ~ 1㎛.
The method of claim 7, wherein

The uneven pattern of the substrate includes a plurality of convex portions, the method of manufacturing a nitride semiconductor light emitting device, characterized in that the flat between the plurality of convex portions.
The method of claim 7, wherein

The uneven pattern of the substrate includes a plurality of convex portions, the method of manufacturing a nitride semiconductor light emitting device, characterized in that the concave between the plurality of convex portions.